[Read-through circular RNA rt-circ-HS promotes hypoxia inducible factor 1α expression and renal carcinoma cell proliferation, migration and invasiveness].

OBJECTIVE: To identify and characterize read-through RNAs and read-through circular RNAs (rt-circ-HS) derived from transcriptional read-through hypoxia inducible factor 1α (HIF1α) and small nuclear RNA activating complex polypeptide 1 (SNAPC1) the two adjacent genes located on chromosome 14q23, in renal carcinoma cells and renal carcinoma tissues, and to study the effects of rt-circ-HS on biological behavior of renal carcinoma cells and on regulation of HIF1α. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and Sanger sequencing were used to examine expression of read-through RNAs HIF1α-SNAPC1 and rt-circ-HS in different tumor cells. Tissue microarrays of 437 different types of renal cell carcinoma (RCC) were constructed, and chromogenic in situ hybridization (ISH) was used to investigate expression of rt-circ-HS in different RCC types. Small interference RNA (siRNA) and artificial overexpression plasmids were designed to examine the effects of rt-circ-HS on 786-O and A498 renal carcinoma cell proliferation, migration and invasiveness by cell counting kit 8 (CCK8), EdU incorporation and Transwell cell migration and invasion assays. RT-PCR and Western blot were used to exa-mine expression of HIF1α and SNAPC1 RNA and proteins after interference of rt-circ-HS with siRNA, respectively. The binding of rt-circ-HS with microRNA 539 (miR-539), and miR-539 with HIF1α 3' untranslated region (3' UTR), and the effects of these interactions were investigated by dual luciferase reporter gene assays. RESULTS: We discovered a novel 1 144 nt rt-circ-HS, which was derived from read-through RNA HIF1α-SNAPC1 and consisted of HIF1α exon 2-6 and SNAPC1 exon 2-4. Expression of rt-circ-HS was significantly upregulated in 786-O renal carcinoma cells. ISH showed that the overall positive expression rate of rt-circ-HS in RCC tissue samples was 67.5% (295/437), and the expression was different in different types of RCCs. Mechanistically, rt-circ-HS promoted renal carcinoma cell proliferation, migration and invasiveness by functioning as a competitive endogenous inhibitor of miR-539, which we found to be a potent post-transcriptional suppressor of HIF1α, thus promoting expression of HIF1α. CONCLUSION: The novel rt-circ-HS is highly expressed in different types of RCCs and acts as a competitive endogenous inhibitor of miR-539 to promote expression of its parental gene HIF1α and thus the proliferation, migration and invasion of renal cancer cells.

[Evaluation of diagnostic efficacy of digital liquid chip method for detection of specific antineutrophil cytoplasmic antibodies].

To explore the clinical diagnostic efficacy of antineutrophil cytoplasmic antibody associated vasculitis (AAV) by comparing the consistency and coincidence rate of serum anti-myeloperoxidase (MPO) antibody and anti-protease 3 (PR3) antibody detected by digital liquid chip method (DLCM) and enzyme-linked immunosorbent assay (ELISA). To provide reference for the selection of detection methods of anti-MPO antibody and anti-PR3 antibody in clinical laboratory. This study is a cross-sectional study, a total of 307 cases of antineutrophil cytoplasmic antibodies were detected in the Department of Clinical Immunology, West China Hospital of Sichuan University from January to March 2021. The serum samples and related clinical information were collected. At the same time, the levels of anti-MPO antibody and anti-PR3 antibody in serum samples were detected by ELISA and DLCM, indirect immunofluorescence (IIF) was used to re-test the differential samples between the two methods. SPSS 26.0 was used to analyze the test results, Cohen's kappa coefficient analysis was used to compare the consistency of the two methods, and paired chi-square test was used to compare the sensitivity and specificity of the two methods to AAV. The results showed that the positive cases of anti-MPO antibody detected by ELISA and DLCM were 63 and 44, and the negative cases were 244 and 263; the positive cases of anti-PR3 antibody detected by ELISA and DLCM were 34 and 28, and the negative cases were 273 and 279. The results of anti-MPO antibody and anti-PR3 antibody detected by the two methods had good consistency and coincidence rate, in which the total coincidence rate of anti-MPO antibody was 92.51%, the positive coincidence rate was 66.67%, and the negative coincidence rate was 99.18%. The results of consistency analysis showed that kappa=0.741 had well consistency. The total coincidence rate of anti-PR3 antibody is 96.74%, the positive coincidence rate is 76.47%, and the negative coincidence rate is 99.27%. The consistency analysis results show that kappa=0.821 had strong consistency. The results of IIF re-test of differential samples showed that the coincidence rate between DLCM and IIF was higher. The results of comparative analysis of anti-MPO antibody and anti-PR3 antibody showed that the specificity of DLCM was better than that of ELISA, and its sensitivity was lower than that of ELISA. In conclusion, the results of anti-MPO antibody and anti-PR3 antibody detected by DLCM were consistent with those of ELISA. In the combined detection of anti-MPO antibody and anti-PR3 antibody, the specificity of DLCM is better than that of ELISA.

[Value of IgA antiphospholipid antibodies in diagnosis of the antiphospholipid syndrome].

Objective: To examine the prevalence of multiple antiphospholipid antibodies (aPL) subtypes in healthy people and antiphospholipid syndrome (APS) patients, and to assess the value of IgA-aPL in the diagnosis of APS. Methods: According to the 2006 Sydney International APS Classification Criteria, a total of 218 APS patients who were admitted to Peking Union Medical College Hospital or West China Hospital of Sichuan University from July to December 2019 were enrolled. Among them, 66 were males, and 152 were females, aged (44.5±15.4) years, including 148 primary APS patients and 70 secondary APS patients. Age-and gender-matched controls were collected at the same period at the ratio of 1∶1 with the APS cases. IgA/IgG/IgM anticardiolipin antibodies (aCL) and anti-ß2 glycoprotein I antibodies (aß2GPI) were detected by chemiluminescent immunoassay. The differences of indicators between groups were analyzed, and the receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of IgA-aPL for APS. Results: The positivity of IgA-aCL and IgA-aß2GPI was 20.6% and 15.6% in the APS patients, while in the IgG/IgM-aCL or IgG/IgM-aß2GPI negative individuals, the isolated positivity of IgA-aCL and IgA-aß2GPI was only 2.3% and 0.9%, respectively. Accordingly, IgA-aCL and IgA-aß2GPI isolated positivity could be used to diagnose APS (P=0.216, 1, respectively). The area under the ROC curve (AUC) of IgG/IgM-aCL for APS diagnosis was 0.833, which was significantly better than that of IgG-aCL alone (AUC=0.776, P<0.001); while the AUC of IgA/IgG/IgM-aCL was 0.833, which could not further increase the diagnostic value for APS (P=0.287). As for aß2GPI, the diagnostic efficacy of combined IgG/IgM (AUC=0.875) or IgA/IgG/IgM (AUC=0.875) antibodies was not superior to IgG-aß2GPI used alone (AUC=0.869, both P>0.05). Besides, patients with IgA-aPL were more likely to have heart valve lesions and thrombocytopenia (both P<0.05). Conclusion: Based on the existing serological markers, such as lupus anticoagulant, IgG/IgM subtype of aCL and aß2GPI, testing IgA-aCL and IgA-aß2GPI cannot further improve the predictive value of APS. However, IgA-aPL is associated with clinical manifestations of APS, including heart valve lesions and thrombocytopenia.

Effects of bovine serum albumin on boar sperm quality during liquid storage at 17°C.

This study aimed to investigate the effects of bovine serum albumin (BSA) on boar sperm quality during liquid storage at 17°C. Boar semen samples were collected and diluted with Modena containing different concentrations (0, 1, 2, 3, 4, 5 and 6 g/l) of BSA, and sperm motility, plasma membrane integrity, acrosome integrity, total antioxidative capacity (T-AOC) activity and malondialdehyde (MDA) content were measured and analysed. The results showed that Modena supplemented with 3, 4 and 5 g/l BSA could improve boar sperm motility, effective survival time and plasma membrane integrity (p < 0.05), decrease MDA content (p < 0.05), while no statistical difference was observed for sperm acrosome integrity and T-AOC activity among these three groups (p > 0.05). The semen sample diluted with Modena containing 4 g/l BSA could achieve optimum effect, and sperm survival time was 7.5 days. After 7 days preservation, sperm motility, plasma membrane integrity and acrosome integrity were 54%, 49% and 78%, respectively. T-AOC activity and MDA content were 1.03 U/ml and 17.5 nmol/ml, respectively. In conclusion, Modena supplemented with BSA reduced the oxidative stress and improved the sperm quality of boar semen during liquid storage at 17°C, and 4 g/l BSA was the optimum concentration. Further studies are required to obtain more concrete results on the determination of antioxidant capacities of BSA in liquid preserved boar semen.

Long non-coding RNA MALAT1 regulates proliferation, apoptosis, migration and invasion via miR-374b-5p/SRSF7 axis in non-small cell lung cancer.

OBJECTIVE: Non-small cell lung cancer (NSCLC) is a common type of lung cancer. Long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was reported to play a tumor-promoting role in NSCLC; however, the regulatory mechanism of MALAT1 in NSCLC progression remains largely unknown. MATERIALS AND METHODS: The expression levels of MALAT1, miR-374b-5p and SRSF7 were measured by quantitative real-time polymerase chain reaction (qRT-PCR), and the protein level of SRSF7 was detected by Western blot analysis. Cell proliferation and apoptosis were determined by cell counting kit-8 (CCK-8) assay and flow cytometry, respectively. Cell migration and invasion were assessed by transwell assay. In addition, starBase3.0 software and dual-luciferase reporter assay were used to identify the correlations between miR-374b-5p and MALAT1 or SRSF7. Nude mouse xenograft assay was performed to explore the effects of MALAT1 on NSCLC in vivo. RESULTS: We first observed that the levels of MALAT1 and SRSF7 were upregulated while miR-374b-5p was downregulated in NSCLC tissues; meanwhile, the expression level of MALAT1 was negatively correlated with miR-374b-5p and positively correlated with SRSF7. Both knockdown of MALAT1 and miR-374b-5p overexpression inhibited proliferation, migration and invasion and induced apoptosis in NSCLC cells. Then, we identified that miR-374b-5p was a target of MALAT1 and SRSF7 was the downstream of miR-374b-5p. In addition, overexpression of SRSF7 reversed the effects of MALAT1 knockdown on proliferation, apoptosis, migration and invasion in NSCLC cells. Finally, overexpression of MALAT1 suppressed NSCLC tumor growth in vivo. CONCLUSIONS: Our results demonstrated that MALAT1 contributed to NSCLC progression through the MALAT1/miR-374b-5p/SRSF7 axis.

Targeting inhibition of K-ras enhances Ad.mda-7-induced growth suppression and apoptosis in mutant K-ras colorectal cancer cells.

Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) is a cancer-specific, growth-suppressing and apoptosis-inducing gene with broad-spectrum antitumor activity. However, when administered by means of a replication-incompetent adenovirus, Ad.mda-7, several colorectal carcinoma cell lines are resistant to its antiproliferative and antisurvival effects. We have presently endeavored to determine if K-ras mutations, present in approximately 40-50% of colorectal cancers and which may mediate resistance to chemotherapy and radiotherapy, represent a predisposing genetic factor mitigating reduced sensitivity to Ad.mda-7. To suppress ras expression, three structurally different replication-incompetent adenoviral vectors were engineered that express (1) an intracellular, neutralizing single-chain antibody (scAb) to p21 ras (Ad.K-ras scAb), (2) an antisense (AS) K-ras gene (Ad.K-ras AS) or (3) both mda-7/IL-24 and a K-ras AS gene in a single bipartite virus (Ad.m7.KAS). Simultaneous inhibition of K-ras and expression of mda-7/IL-24 enhanced killing of colorectal carcinoma cells with mutated K-ras, but not with wild-type K-ras. The extent of killing depended on the degree of K-ras downregulation, with Ad.K-ras AS being generally more efficient than Ad.K-ras scAb in combination with Ad.mda-7. These findings support an effective dual-combinatorial approach for the therapy of colorectal cancers that employs a unique cancer-specific suppressor gene (mda-7/IL-24) with targeted inhibition of oncogene (ras) expression.

Ionizing radiation enhances therapeutic activity of mda-7/IL-24: overcoming radiation- and mda-7/IL-24-resistance in prostate cancer cells overexpressing the antiapoptotic proteins bcl-xL or bcl-2.

Subtraction hybridization applied to terminally differentiating human melanoma cells identified mda-7/IL-24, a cytokine belonging to the IL-10 gene superfamily. Adenoviral-mediated delivery of mda-7/IL-24 (Ad.mda-7) provokes apoptosis selectively in a wide spectrum of cancers in vitro in cell culture, in vivo in human tumor xenograft animal models and in patients with advanced carcinomas and melanomas. In human prostate cancer cells, a role for mitochondrial dysfunction and induction of reactive oxygen species in the apoptotic process has been established. Ectopic overexpression of bcl-xL and bcl-2 prevents these changes including apoptosis induction in prostate tumor cells by Ad.mda-7. We now document that this resistance to apoptosis can be reversed by treating bcl-2 family overexpressing prostate tumor cells with ionizing radiation in combination with Ad.mda-7 or purified GST-MDA-7 protein. Additionally, radiation augments apoptosis induction by mda-7/IL-24 in parental and neomycin-resistant prostate tumor cells. Radiosensitization to mda-7/IL-24 is dependent on JNK signaling, as treatment with the JNK 1/2/3 inhibitor SP600125 abolishes this effect. Considering that elevated expression of bcl-xL and bcl-2 are frequent events in prostate cancer development and progression, the present studies support the use of ionizing radiation in combination with mda-7/IL-24 as a means of augmenting the therapeutic benefit of this gene in prostate cancer, particularly in the context of tumors displaying resistance to radiation therapy owing to bcl-2 family member overexpression.

Surface-epitope masking: a strategy for the development of monoclonal antibodies specific for molecules expressed on the cell surface.

BACKGROUND: Producing monoclonal antibodies against specific targets, including tumor-specific antigens, is a tedious and extremely inefficient process. PURPOSE: Our purpose was to determine whether DNA transfection combined with an immunologic masking tactic could be used to efficiently generate hybridomas that secrete monoclonal antibodies. The quest was for monoclonal antibodies that would react with molecules existing on the surface of genetically altered cells. METHODS: We developed a masking technique called surface-epitope masking (SEM). The SEM procedure involves the selective blocking of surface antigens present in a genetically engineered cell (referred to as a "tester") with high-titer polyclonal antibodies that have been produced against the untransfected parental cell (referred to as a "driver"). Surface-epitope-masked tester cells were injected into BALB/c mice; immune spleen cells then taken from these mice were fused with myeloma cells. RESULTS: This process resulted in the efficient generation of hybridomas that secreted monoclonal antibodies that reacted with cell-surface antigens on transfected tester cells and with additional cell types that expressed the same surface molecules. In one case, CREF-Trans 6 cells were engineered to express a typical multidrug-resistant (MDR) phenotype. Using CREF-Trans 6:MDR cells as a tester cell line, we utilized the SEM procedure to produce monoclonal antibodies that displayed surface reactivity to both CREF-Trans 6:MDR cells and MDR human breast carcinoma (MCF7) cells. In a second case, human prostatic carcinoma CREF-Trans 6 cells, which were DNA transfected and derived from nude mouse tumors, were used as the tester cell line. The SEM procedure was again used to produce monoclonal antibodies. These antibodies were designed to and did react with: (a) tumor-associated antigens on the surface of the original LNCaP cell line used to obtain human prostatic carcinoma DNA, (b) primary and secondary nude mouse transfectants derived from tumors, and (c) two additional human prostatic carcinoma cell lines, DU-145 and PC-3. CONCLUSIONS: The SEM approach was used for the efficient and selective development of monoclonal antibodies that react with cell-surface molecules with both known and unknown functions. IMPLICATIONS: The SEM procedure should be useful in producing monoclonal antibodies and identifying genes associated with important cellular processes, including immunologic recognition, tumorigenesis, metastasis, atypical multidrug resistance, and autoimmune diseases.

Growth suppression and toxicity induced by caffeic acid phenethyl ester (CAPE) in type 5 adenovirus-transformed rat embryo cells correlate directly with transformation progression.

The active component of the honeybee hive product propolis, caffeic acid phenethyl ester (CAPE), induces a selective growth suppressive and toxic effect toward cloned rat embryo fibroblast cells transformed by adenovirus type 5 (Ad5) or the Ad5 E1A transforming gene versus untransformed cloned rat embryo fibroblast cells (Z-z. Su et al., Mol. Carcinog., 4: 231-242, 1991). The present study was conducted to determine whether CAPE-induced growth suppression/toxicity was a direct result of expression of the Ad5 E1A and E1B transforming genes or a consequence of the action of these genes resulting in the transformed state. For this investigation we used somatic cell hybrids and 5-azacytidine-treated Ad5-transformed rat embryo cells that display different stages of expression of the transformed phenotype. This series of cell lines has permitted us to determine whether expression of the transformed state and the stage of transformation progression regulates CAPE sensitivity. Evidence is presented indicating that sensitivity to CAPE is directly determined by the state of expression of the transformed progression phenotype, as opposed to simply the expression of the Ad5 E1A and E1B transforming genes. These results provide further evidence that CAPE may represent a unique compound that can specifically target progressed transformed cells for growth suppression and toxicity. An understanding of the mechanism underlying this selective effect of CAPE could result in the identification of important biochemical pathways mediating cellular transformation and progression of the transformed state.

Wild-type adenovirus type 5 transforming genes function as transdominant suppressors of oncogenesis in mutant adenovirus type 5 transformed rat embryo fibroblast cells.

Transformation of cloned rat embryo fibroblast (CREF) cells with the host-range adenovirus type 5 (Ad5) mutant, H5hr1, results in transformants with a fibroblastic morphology which displays a cold-sensitive transformation phenotype and oncogenic potential in both nude mice and syngeneic rats. In contrast, wild-type (wt) Ad5 transformed CREF cells are epithelioid in morphology, temperature independent for transformation, and nontumorigenic. The present studies were conducted to analyze the contribution of the mutated E1A and E1B regions of H5hr1 in regulating the biological properties of H5hr1-transformed CREF cells. CREF cells were constructed which contain the mutated E1A and E1B transforming regions of H5hr1 and either a wt Ad5 E1A gene, a wt Ad5 E1B gene, or both a wt Ad5 E1A and a wt E1B gene. A wt Ad5 E1A gene was sufficient in reversing the cold-sensitive transformation phenotype. By using a wt Ad5 E1A gene under the transcriptional control of a dexamethasone-inducible mouse mammary tumor virus promoter, a direct suppressive effect of wt Ad5 E1A on colony formation in monolayer culture and agar growth of H5hr1-transformed cells was demonstrated. Expression of a wt Ad5 E1A, a wt Ad5 E1B, or both wt transforming genes in H5hr1-transformed CREF cells also suppressed oncogenicity. The ability or inability to form tumors in animals was found not to correlate with sensitivity to natural killer cell-mediated lysis. These results indicate that both the wt Ad5 E1A and wt Ad5 E1B genes can function as dominant suppressors of the oncogenic process when coexpressed in H5hr1-transformed CREF cells. This effect does not require large quantities of wt Ad5 E1A or E1B transforming proteins, nor is it directly related to the acquisition of a natural killer cell cytolysis-susceptible phenotype.

Defining the critical gene expression changes associated with expression and suppression of the tumorigenic and metastatic phenotype in Ha-ras-transformed cloned rat embryo fibroblast cells.

Carcinogenesis requires a complex series of genetic changes often involving multiple oncogenes and the inactivation of multiple tumor-suppressor genes. We presently examined the effect of the Krev-1 tumor-suppressor gene on the tumorigenic and metastatic potential of Ha-ras-transformed cloned rat embryo fibroblast (CREF) cells. Ha-ras-transformed CREF cells are morphologically transformed and anchorage independent; produce reduced levels of nm23-H1 (a putative metastasis-suppressor gene product) and TIMP-1 (tissue inhibitor of metalloproteinase 1) transcripts and mRNA compared with CREF cells; produce increased levels of cripto, 94-kDa gelatinase/type IV collagenase (94-kDa GEL), osteopontin (OPN) and transin/stromelysin transcripts and mRNA compared with CREF cells; and are tumorigenic and metastatic in both nude mice and syngeneic rats. Ha-ras-transformed CREF cells coexpressing the Krev-1 gene display a reversion in cellular phenotype and gene expression to that of untransformed CREF cells. However, Ha-ras/Krev-1-coexpressing CREF cells retain, albeit with extended latency periods, both tumorigenic and metastatic potential that is not related directly to the final level of Ha-ras or Krev-1 mRNA or the Ha-ras p21 transforming protein. Development of metastatic potential is, however, directly correlated with a reduction in nm23-H1 and TIMP-1 transcription and mRNA levels and an enhanced expression of cripto, 94-kDa GEL, osteopontin and transin. In contrast, expression of additional tumor-suppressor genes, such as the RB gene and p53, or genes associated with tumorigenesis in other model systems, such as major excreted glycoprotein (MEP), 72-kDa gelatinase/type IV collagenase (72-kDa GEL), fibronectin (FIB), tenascin and intracellular adhesion molecule 1 (ICAM-1) is not altered in a consistent manner during in vitro transformation suppression or escape from tumorigenic and metastatic suppression. These results indicate that Krev-1 suppression of the Ha-ras-transformed/oncogenic phenotype is associated with a distinct program of gene expression changes manifested by altered rates of transcription and steady-state mRNA levels of specific oncogenic-suppressing and oncogenic-inducing genes. These data support a model of Ha-ras-induced metastasis in CREF cells that involves a direct modulation in the expression/suppression of specific combinations of oncogenic-suppressor genes and metastasis-promoting genes that are regulated coordinately in the process of tumor progression.

Induction of transformation progression in type 5 adenovirus-transformed rat embryo cells by a cloned protein kinase C beta 1 gene and reversal of progression by 5-azacytidine.

Protein kinase C (PKC) is a key component in signal transduction in eucaryotic cells and when specific PKC isoforms are over-expressed in immortal mammalian cells they can induce transformation-associated properties. In the present study we demonstrate that a cloned PKC beta 1 gene can induce an enhanced expression of the transformed phenotype in type 5 adenovirus (Ad5)-transformed rat embryo (RE) cells (clone E11), a process termed transformation progression. E11 cells expressing the PKC beta 1 gene, clone B1/PKC, produce PKC beta 1 mRNA and display enhanced PKC enzymatic activity and binding of [3H]-phorbol-12,13-dibutyrate (PDBu) to cell surface phorbol ester receptors. B1/PKC cells grow with increased efficiency in agar in comparison with parental E11 cells and anchorage-independence is further enhanced in both cell types by addition of the tumor promoting agent 12-0-tetradecanoyl-phorbol-13-acetate (TPA). A single-exposure of B1/PKC cells to 5-azacytidine (AZA), followed by growth in the absence of this demethylating agent, results in B1/PKC-AZA clones which display a stable reversion of the progression phenotype to that of the unprogressed parental E11 clone. Loss of the progression phenotype corresponds with a reduction in PKC beta 1-induced biochemical and cellular changes. In contrast, progression-suppression does not involve an alteration in expression of the Ad5 transforming genes, E1A and E1B, or the endogenous PKC epsilon gene. TPA cannot induce the progression phenotype in B1/PKC-AZA cells, but it can reversibly induce an increase in the transcriptional rate and steady-state mRNA levels of PKC beta 1 and c-jun and it increases AP-1 DNA-binding. These results indicate that the PKC beta 1 gene can serve as a transformation progression-inducing gene in rat embryo cells previously transformed by Ad5 and progression may be mediated by the inactivation by methylation of an AZA-sensitive 'progression suppressor gene(s)'. The suppression process in B1/PKC cells is independent of expression of the Ad5-transforming genes but correlates directly with the reduced expression of the transfected PKC beta 1 gene in AZA-treated B1/PKC cells.

c-fos is a positive regulator of carcinogen enhancement of adenovirus transformation.

The early gene expression changes mediating carcinogen enhancement of viral transformation (CET) remain to be elucidated. A model cell culture system has been developed that is now permitting a molecular analysis of CET. Pretreatment of cloned rat embryo fibroblast (CREF) cells with methyl methanesulfonate (MMS) prior to infection with the cold-sensitive host-range type 5 adenovirus mutant, H5hr1, results in a dose-dependent increase in viral transformation. The present study investigates the role of immediate-early response genes, specifically c-fos, in the CET process. MMS pretreatment, alone or in combination with infection with H5hr1 temporally and differentially increases c-fos, c-jun, jun-B, jun-D and c-myc steady-state mRNA levels. Maximum induction occurs with c-fos and c-jun 8 to 12 h posttreatment and the magnitude of response is generally greatest in CREF cells pretreated with MMS and then infected with H5hr1. Enhancement in RNA levels is observed in the presence of cycloheximide indicating that ongoing protein synthesis is not required for induction of c-fos, c-jun, jun-B or c-myc expression. Nuclear run-on analysis indicates an enhancement in transcriptional rates for c-fos, c-jun, jun-B and c-myc in CREF cells treated with MMS or MMS plus infection with H5hr1. A requirement for elevated c-fos in the early stages of CET is indicated by the ability of c-fos antisense oligonucleotides to prevent the CET process. Direct evidence implicating early increases in c-fos as a mediator of the CET process is demonstrated by stably expressing mouse mammary tumor virus promoter-regulated human sense and antisense c-fos genes in CREF cells. Induction of c-fos sense expression by dexamethasone (DEX) in the absence of MMS treatment results in enhanced c-fos mRNA, Fos protein, AP-1 DNA-binding activity and H5hr1-induced transformation and CET. Induction of c-fos expression by DEX in stable c-fos-sense CREF constructs also results in elevated levels of c-jun, jun-B and c-myc mRNA and protein. Conversely, induction of c-fos antisense expression prevents the increase in c-fos mRNA, Fos protein and AP-1 DNA-binding activity and eliminates CET. In the antisense-c-fos constructs, increases in c-jun, jun-B and c-myc mRNA and protein normally induced by MMS also are not apparent. Thus, induction or inhibition in c-fos expression affects the level of expression of additional immediate-early response genes, including c-jun, jun-B and c-myc.(ABSTRACT TRUNCATED AT 400 WORDS)

Induction of differentiation in human promyelocytic HL-60 leukemia cells activates p21, WAF1/CIP1, expression in the absence of p53.

The melanoma differentiation associated gene, mda-6, which is identical to the P53-inducible gene WAF1/CIP1, encodes an M(r) 21,000 protein (p21) that can directly inhibit cell growth by repressing cyclin dependent kinases. mda-6 was identified using subtraction hybridization by virtue of its enhanced expression in human melanoma cells induced to terminally differentiate by treatment with human fibroblast interferon and the anti-leukemic compound mezerein (Jiang and Fisher, 1993). In the present study, we demonstrate that mda-6 (WAF1/CIP1) is an immediate early response gene induced during differentiation of the promyelocytic HL-60 leukemia cell line along the granulocytic or macrophage/monocyte pathway. mda-6 gene expression in HL-60 cells is induced within 1 to 3 h during differentiation along the macrophage/monocyte pathway evoked by 12-0-tetradecanoyl phorbol-13-acetate (TPA) or 1,25-dihydroxyvitamin D3 (Vit D3) or the granulocytic pathway produced by retinoic acid (RA) or dimethylsulfoxide (DMSO). Immunoprecipitation analyses using an anti-p21 antibody indicate a temporal induction of p21 protein following treatment with TPA, DMSO or RA. A relationship between rapid induction of mda-6 gene expression and differentiation is indicated by a delay in this expression in an HL-60 cell variant resistant to TPA-induced growth arrest and differentiation. A similar delay in mda-6 gene expression is not observed in Vit D3 treated TPA-resistant variant cells that are also sensitive to induction of monocytic differentiation. Since HL-60 cells have a null-p53 phenotype, these results demonstrate that p21 induction occurs during initiation of terminal differentiation in a p53-independent manner. In this context, p21 may play a more global role in growth control and differentiation than originally envisioned.

Analysis of viral and cellular gene expression during progression and suppression of the transformed phenotype in type 5 adenovirus-transformed rat embryo cells.

Transformation of secondary Sprague-Dawley rat embryo (RE) cells with type 5 adenovirus (Ad5) results in morphologically transformed cells which can undergo a series of sequential changes resulting in enhanced expression of the transformed phenotype, a process termed progression. Selection for a progressed phenotype often occurs after growth in agar or tumor formation in nude mice, and this process is reversible following treatment of cells with 5-azacytidine. In the present study we have analyzed a series of clonal populations of Ad5-transformed RE cells representing different stages in a defined progression lineage. Progression was not associated with alterations in the steady-state levels of mRNA produced by the viral transforming genes, E1A and E1B, or the cellular gene, c-myc. In addition, the tumor-promoting agent 12-O-tetradecanoyl-phorbol-13-acetate (TPA), which induces expression of a progressed phenotype in Ad5-transformed RE cells, did not significantly alter the RNA transcription rates of the Ad5 E1A or E1B genes, the TPA-inducible gene TPA-S1 or the TPA-responsive genes Pro1 or protein kinase C. TPA did, however, increase by 1 h the steady-state level of c-fos mRNA, but this effect was similar in both progressed and unprogressed cells. Progression also did not involve a change in the RNA transcription rate of a number of cellular and viral genes, including actin, c-Ha-ras, c-myc, v-fos, erbB, TGF-alpha, TGF-beta, Pro-2, transin, TPA-R1, v-myb and c-mos, or other adenovirus genes in addition to E1A and E1B, including E2A and E4. Immunoblotting analysis using E1B polyclonal antiserum further indicated that progression was not associated with changes in the levels of an Mr 21,000 polypeptide encoded by E1B. Similarly, immunoprecipitation analysis with an Ad2 E1A monoclonal antibody indicated similar levels of the Mr 55,000 and 48,000 E1A polypeptides, as well as coprecipitated proteins of Mr 300,000, 107,000 and 105,000 [which is the retinoblastoma (Rb) protein], in E11 and E11-NMT cells. Immunoprecipitation of cell lysates with a monoclonal antibody specific for the Mr 105,000 Rb protein further demonstrated that progression also was not associated with a change in the level or state of phosphorylation of the Rb protein. However, transfection of a human Rb gene (also containing a neomycin resistance gene) into Ad5-transformed RE cells was more inhibitory, with respect to formation of G418-resistant colonies, in unprogressed than in progressed Ad5-transformed RE cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Subtraction hybridization identifies a novel melanoma differentiation associated gene, mda-7, modulated during human melanoma differentiation, growth and progression.

Cultured human melanoma cells lose proliferative capacity and terminally differentiate after treatment with the combination of recombinant human fibroblast interferon (IFN-beta) and mezerein (MEZ). Subtraction hybridization of cDNA libraries prepared from actively proliferating human H0-1 melanoma cells from cDNA libraries produced from H0-1 cells treated with IFN-beta + MEZ identifies a novel melanoma differentiation-associated (mda) cDNA, mda-7, that displays elevated expression in differentiation inducer-treated H0-1 cells. mda-7 encodes a novel protein of 206 amino acids with a predicted size of 23.8 kDa. The level of mda-7 mRNA is elevated in actively proliferating normal human melanocytes versus primary and metastatic human melanomas. In the Matrigel-assisted melanoma progression model, mda-7 expression decreases in early vertical growth phase primary human melanoma cells selected for autonomous or enhanced tumor formation in nude mice. Treatment of human melanomas with IFN-beta + MEZ, and to a lesser extent with MEZ, results in growth suppression and induced or enhanced mda-7 expression. Immunoprecipitation analyses using peptide-derived rabbit polyclonal antibodies detect increases in mda-7 protein, and a higher molecular weight protein of approximately 90 to 100 kDa, in MEZ and IFN-beta + MEZ treated H0-1 cells. mda-7 is a highly conserved gene with an homologous sequence in the genome of yeast. Transfection of mda-7 expression constructs into H0-1 and C8161 human melanoma cells reduces growth and inhibits colony formation. These results confirm that mda-7 has antiproliferative properties in human melanoma cells and in this context may contribute to terminal cell differentiation. The mda-7 gene may also function as a negative regulator of melanoma progression.

The melanoma differentiation-associated gene mda-6, which encodes the cyclin-dependent kinase inhibitor p21, is differentially expressed during growth, differentiation and progression in human melanoma cells.

The combination of recombinant human fibroblast interferon (IFN-beta) and the antileukemic compound mezerein (MEZ) induces terminal differentiation with an irreversible loss of proliferative capacity in human melanoma cells. Using subtraction hybridization, cDNAs were identified that display enhanced expression in terminally differentiated and growth arrested human melanoma cells (Jiang and Fisher, 1993; Jiang et al., 1994a). A specific melanoma differentiation-associated (mda) cDNA, mda-6, is described whose expression inversely correlates with melanoma progression and growth. mda-6 is identical to WAF1/CIP1/SDI1 that encodes the M(r) 21,000 protein (p21) that is an inhibitor of cyclin-dependent kinases. Actively growing normal melanocyte, SV40-immortalized human melanocyte and dysplastic nevus cell lines synthesize elevated levels of mda-6 mRNA; whereas, actively proliferating radial and early vertical growth phase primary melanomas as well as metastatic human melanoma cells produce reduced levels of mda-6 mRNA. Treatment of primary and metastatic human melanoma cells with IFN-beta + MEZ results in growth inhibition and an increase in mda-6 expression. mda-6 expression also increases when human melanoma cells are grown to high saturation densities or when grown in serum-free medium. Using anti-p53 and anti-p21 antibodies, an inverse correlation is found between p53 and p21 protein levels during growth arrest and differentiation. Induction of growth arrest and terminal differentiation in H0-1 human melanoma cells by IFN-beta + MEZ results in a temporal decrease in wild-type p53 protein levels with a corresponding increase in p21 levels. In the Matrigel-assisted melanoma progression model, mda-6 expression decreases in early vertical growth phase primary human melanoma cells selected for autonomous or enhanced tumor formation in nude mice. In metastatic human melanoma cells displaying a loss of metastatic potential resulting from introduction of a normal human chromosome 6, mda-6 mRNA levels increase. Taken together, these studies indicate that mda-6 (p21) may function as a negative regulator of melanoma growth, progression and metastasis.

Ionizing radiation modulates vascular endothelial growth factor (VEGF) expression through multiple mitogen activated protein kinase dependent pathways.

We investigated the role of radiation-induced mitogen activated protein kinase (MAPK) pathway activity in the regulation of proliferation, cell survival and vascular endothelial growth factor (VEGF) production in primary astrocytes and in T9 and RT2 glioblastoma cells derived from Fisher 344 rats. In these cells, ionizing radiation (2 Gy) caused activation of the MAPK pathway which was blocked by specific inhibitor drugs. Blunting of radiation-induced MAPK activity weakly enhanced radiation-induced apoptosis 24 h after exposure in RT2 cells. Furthermore, blunting of MAPK activation weakly enhanced the ability of radiation to reduce RT2 cell growth in clonogenic growth assays. These findings argue that inhibition of MAPK signaling reduces proliferation and enhances cell killing by ionizing radiation in transformed astrocytes. Proliferation and survival of cancer cells has been linked in vivo to enhanced expression of angiogenic growth factors. Recently we demonstrated that the gene product of a novel rodent radiation-responsive gene, progression elevated gene 3 (PEG-3), could enhance vascular endothelial growth factor (VEGF) promoter activity in rodent fibroblasts, leading to increased VEGF protein levels and tumorigenic behavior in vivo. Thus PEG-3 and VEGF expression could be expected to directly correlate with the oncogenic potential of transformed cells. RT2 cells expressed more PEG-3 and VEGF protein than T9 cells, and were more tumorigenic in vivo than T9 cells. Radiation activated the PEG-3 promoter via MAPK signaling and ectopic over-expression of PEG-3 enhanced both basal MAPK activity and basal VEGF promoter activity. Basal MAPK activity partially correlated with basal VEGF promoter activity and VEGF protein levels in primary astrocytes, T9 and RT2 cells. Radiation increased the activity of the VEGF promoter and VEGF protein levels in primary astrocytes, T9 and RT2 cells which were dependent upon MAPK function. Furthermore, inhibition of AP-1 transcription factor signaling by dominant negative c-Jun (TAM67) also significantly reduced basal, and to a lesser extent radiation-induced, VEGF promoter function in RT2 cells. Collectively, our data demonstrate that radiation-induced MAPK signaling can both protect cells from radiation-induced cell death as well as enhance protein levels of pro-angiogenic factors such as VEGF. Enhanced VEGF expression in RT2 cells may be mediated via MAPK and JNK pathway signaling which converges upon the AP-1 transcription factor complex.

Translational infidelity and human cancer: role of the PTI-1 oncogene.

Several components of the eukaryotic protein synthesis apparatus have been associated with oncogenic transformation of cells. Altered expression of translation elongation factor 1 alpha (EF-1 alpha), a core component of protein synthesis and closely related sequences have been linked with transformed phenotypes by several independent studies, in diverse systems. A dominant acting oncogene, prostate tumor inducing gene-1 (PTI-1) has provided further evidence for this link. PTI-1 appears to be a hybrid molecule with components derived from both prokaryotic and eukaryotic origins. The predicted protein coding moiety represents an EF-1 alpha molecule, truncated N-terminal to amino acid residue 68 and having six additional point mutations. This coding sequence is fused to a 5' untranslated region (UTR) showing strongest homology to ribosomal RNA derived from Mycoplasma hyopneumoniae. Expression studies using the cloned cDNA in nude mouse tumor formation assays have confirmed the oncogenic nature of the molecule. A broad spectrum of tumor derived cell lines, from varied tissue sources and blood samples from patients having confirmed prostate carcinoma, all scored positive for expression of PTI-1, while corresponding normal tissues or blood samples were negative. Based on its near identity to EF-1 alpha, it is proposed that PTI-1 represents a new class of oncogene whose transforming capacity probably arises through mechanisms including: (i) protein translational infidelity, resulting in the synthesis of mutant polypeptides due to loss of proofreading function during peptide chain elongation, (ii) by its association with and alteration of the cytoskeleton, (iii) by impinging on one particular or several different signal transduction pathways through its properties as a G-protein.

Ultraviolet-irradiated simian virus 40 activates a mutator function in rat cells under conditions preventing viral DNA replication.

The UV-irradiated temperature-sensitive early SV40 mutant tsA209 is able to activate at the nonpermissive temperature the expression of mutator and recovery functions in rat cells. Unirradiated SV40 activates these functions only to a low extent. The expression of these mutator and recovery functions in SV40-infected cells was detected using the single-stranded DNA parvovirus H-1 as a probe. Because early SV40 mutants are defective in the initiation of viral DNA synthesis at the nonpermissive temperature, these results suggest that replication of UV-damaged DNA is not a prerequisite for the activation of mutator and recovery functions in mammalian cells. The expression of the mutator function is dose-dependent, i.e., the absolute number of UV-irradiated SV40 virions introduced per cell determines its level. Implications for the interpretation of mutation induction curves in the progeny of UV-irradiated SV40 in permissive host cells are discussed.