Anti-ENO1 antibody combined with metformin against tumor resistance: a novel antibody-based platform.

Background: Antibody-based platforms (i.e., ADC) have emerged as one of the most encouraging tools for the cancer resistance caused by cancer stem cells (CSCs) enrichment. Our study might provide a promising therapeutic direction against drug resistance and serve as a potential precursor platform for screening ADC. Methods: The cell migration, invasion, drug resistance, and self-renewal were assessed by the cell invasion and migration assay, wound healing assay, CCK-8 assay, colony formation assay, and sphere formation assay, respectively. The expression profiles of CSCs (ALDH+ and CD44+) subpopulations were screened by flow cytometry. The western blot and cell immunofluorescence assay were used to evaluate pathway-related protein expression in both anti-ENO1 antibody, MET combined with DPP/CTX-treated CSCs. Results: In the present study, western blot and flow cytometry verified that anti-ENO1 antibody target the CD44+ subpopulation by inhibiting the PI3K/AKT pathway, while metformin might target the ALDH+ subpopulation through activation of the AMPK pathway and thus reverse drug resistance to varying degrees. Subsequently, in vitro investigation indicated that anti-ENO1 antibody, metformin combined with cisplatin/cetuximab could simultaneously target ALDH+ and CD44+ subpopulations. The combination also inhibited the CSCs proliferation, migration, invasion, and sphere formation; which may result in overcoming the drug resistance. Then, molecular mechanism exploration verified that the anti-ENO1 antibody, metformin combined with cisplatin/cetuximab inhibited the Wnt/ß-catenin signaling. Conclusions: The study preliminarily revealed anti-ENO1 antibody combined with metformin could overcome drug resistance against CSCs by inhibiting the Wnt//ß-catenin pathway and might serve as a potential precursor platform for screening ADC. More importantly, it is reasonably believed that antibody-based drug combination therapy might function as an encouraging tool for oncotherapy.

HSP90, as a functional target antigen of a mAb 11C9, promotes stemness and tumor progression in hepatocellular carcinoma.

BACKGROUND: Identification of promising targeted antigens that exhibited cancer-specific expression is a crucial step in the development of novel antibody-targeted therapies. We here aimed to investigate the anti-tumor activity of a novel monoclonal antibody (mAb) 11C9 and identify the antibody tractable target in the hepatocellular cancer stem cells (HCSCs). METHODS: The identification of the targeted antigen was conducted using SDS-PAGE, western blot, mass spectrometry, and co-immunoprecipitation. Silence of HSP90 was induced by siRNA interference. Positive cells were sorted by fluorescence-activated cell sorting. Double-immunofluorescent (IF) staining and two-color flow cytometry detected the co-expression. Self-renewal, invasion, and drug resistance were assessed by sphere formation, matrigel-coated Transwell assay, and CCK-8 assay, respectively. Tumorigenicity was evaluated in mouse xenograft models. RNA-seq and bioinformatics analysis were performed to explore the mechanism of mAb 11C9 and potential targets. RESULTS: MAb 11C9 inhibited invasion and self-renewal abilities of HCC cell lines and reversed the cisplatin resistance. HSP90 (~ 95 kDa) was identified as a targeted antigen of mAb 11C9. Tissue microarrays and online databases revealed that HSP90 was overexpressed in HCC and associated with a poor prognosis. FACS and double-IF staining showed the co-expression of HSP90 and CSCs markers (CD90 and ESA). In vitro and in vivo demonstrated the tumorigenic potentials of HSP90. The inhibition of HSP90 by siRNA interference or 17-AAG inhibitor both decreased the number of invasion, sphere cells, and CD90+ or ESA+ cells, as well as reversed the resistance. Bioinformatics analysis and western blot verified that HSP90 activated Wnt/ß-catenin signaling. CONCLUSIONS: The study preliminarily revealed the anti-tumor activity of mAb 11C9. More importantly, we identified HSP90 as a targeted antigen of mAb 11C9, which functions as an oncogene in phenotype shaping, stemness maintenance, and therapeutic resistance by activating Wnt/ß-catenin signaling.

Palladin promotes cancer stem cell-like properties in lung cancer by activating Wnt/Β-Catenin signaling.

BACKGROUND: Cancer stem cells (CSCs) are responsible for drug resistance, cancer relapse, and metastasis. Here, we report the first analysis of Palladin expression and its impacts on stem cell-like properties in lung cancer. METHODS: Tissue microarrays were used to investigate Palladin expression and its association with prognosis. Immunofluorescence (IF), flow fluorescence assay, and Western blot were performed to detect Palladin expression in 6 NSCLC cell lines. Cell phenotypes and drug resistance were evaluated. Xenograft models were constructed to confirm the role of Palladin in vivo. RESULTS: By using the tissue microarrays, Palladin was identified to be highly expressed in the cytoplasm, specifically in the cytomembrane of NSCLC, and its high expression is associated with poor prognosis. Palladin is widely expressed and enriched in the sphere cells. The in vitro and in vivo studies showed that Palladin promoted stem cell-like properties, including cell viability, invasion, migration, self-renewal abilities, taxol resistance, and tumorigenicity. Western blot revealed that Palladin promoted the accumulation of ß-catenin and activated Wnt/ß-catenin signaling. Tissue microarrays analysis further confirmed the positive correlation between Palladin and ß-catenin. Wnt/ß-catenin pathway inhibitor blocked the Palladin-induced enhancement of sphere-forming. CONCLUSIONS: Palladin might act as an oncogene by promoting CSCs-like properties and tumorigenicity of NSCLC cells via the Wnt/ß-catenin signaling pathway. Besides, Palladin was identified to have the potential as a cell surface marker for LCSCs identification. These findings provide a possible target for developing putative agents targeted to LCSCs.

MYH9 is crucial for stem cell-like properties in non-small cell lung cancer by activating mTOR signaling.

The fatality rate of non-small cell lung cancer (NSCLC) has been high due to the existence of cancer stem cells (CSCs). Non-muscle myosin heavy chain 9 (MYH9) can promote the progression of various tumors, but its effect on the stem cell-like characteristics of lung cancer cells (LCCs) has not been clarified. Our research found that the stemness characteristics of LCCs were significantly enhanced by the overexpression of MYH9, and the knockout of MYH9 had the opposite effects. The in vivo with inhibitor blebbistatin further confirmed the effect of MYH9 on the stem cell-like behavior of LCCs. Furthermore, western blotting showed that the expression level of CSCs markers (CD44, SOX2, Nanog, CD133, and OCT4) was also regulated by MYH9. Mechanistic studies have shown that MYH9 regulates stem cell-like features of LCCs by regulating the mTOR signaling pathway, which was supported by sphere formation experiments after LCCs were treated with inhibitors Rapamycin and CHIR-99021. Importantly, high expression of MYH9 in lung cancer is positively correlated with poor clinical prognosis and is an independent risk factor for patients with NSCLC.

Analysis of microRNA expression in CD133 positive cancer stem­like cells of human osteosarcoma cell line MG-63.

Osteosarcoma (OS) is a primary malignant tumor of bone occurring in young adults. OS stem cells (OSCs) play an important role in the occurrence, growth, metastasis, drug resistance and recurrence of OS. CD133 is an integral membrane glycoprotein, which has been identified as an OSC marker. However, the mechanisms of metastasis, chemoresistance, and progression in CD133(+) OSCs need to be further explored. In this study, we aim to explore differences in miRNA levels between CD133(+) and CD133(-) cells from the MG-63 cell line. We found 20 differentially expressed miRNAs (DEmiRNAs) (16 upregulated and 4 downregulated) in CD133(+) cells compared with CD133(-) cells. Hsa-miR-4485-3p, hsa-miR-4284 and hsa-miR-3656 were the top three upregulated DEmiRNAs, while hsa-miR-487b-3p, hsa-miR-493-5p and hsa-miR-431-5p were the top three downregulated DEmiRNAs. In addition, RT-PCR analysis confirmed that the expression levels of hsa-miR-4284, hsa-miR-4485-3p and hsa-miR-3656 were significantly increased, while the expression levels of hsa-miR-487b-3p, hsa-miR-493-5p, and hsa-miR-431-5p were significantly decreased in CD133(+) cells compared with CD133(-) cells. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that predicted or validated target genes for all 20 DEmiRNAs or the selected 6 DEmiRNAs participated in the "PI3K-Akt signaling pathway," "Wnt signaling pathway," "Rap1 signaling pathway," "Cell cycle" and "MAPK signaling pathway". Among the selected six DEmiRNAs, miR-4284 was especially interesting. MiR-4284 knockdown significantly reduced the sphere forming capacity of CD133(+) OS cells. The number of invasive CD133(+) OS cells was markedly decreased after miR-4284 knockdown. In addition, miR-4284 knockdown increased the p-ß-catenin levels in CD133(+) OS cells. In conclusion, RNA-seq analysis revealed DEmiRNAs between CD133(+) and CD133(-) cells. MiRNAs might play significant roles in the function of OSCs and could serve as targets for OS treatment. MiR-4284 prompted the self-renewal and invasion of OSCs. The function of miR-4284 might be associated with the Wnt signaling pathway.

BCAT1 Activates PI3K/AKT/mTOR Pathway and Contributes to the Angiogenesis and Tumorigenicity of Gastric Cancer.

BACKGROUND: Focusing on antiangiogenesis may provide promising choices for treatment of gastric cancer (GC). This study aimed to investigate the mechanistic role of BCAT1 in the pathogenesis of GC, particularly in angiogenesis. METHODS: Bioinformatics and clinical samples analysis were used to investigate the expression and potential mechanism of BCAT1 in GC. BGC823 cells with BCAT1 overexpression or silencing were induced by lentiviral transduction. Cell phenotypes and angiogenesis were evaluated. The relevant proteins were quantized by Western blotting, immunohistochemistry, or immunofluorescence. Xenograft models were constructed to confirm the role of BCAT1 in vivo. RESULTS: BCAT1 was overexpressed in GC patients and associated with lower survival. BCAT1 expression was correlated with proliferation-, invasion-, or angiogenesis-related markers expression and pathways. Silencing BCAT1 expression suppressed cell viability, colony formation, cycle progression, invasion, and angiogenesis of BGC823 cells, as well as the tumor growth of xenograft models, whereas overexpressing BCAT1 had the opposite results both in vitro and in vivo. Bioinformatics analysis and Western blotting demonstrated that BCAT1 activated the PI3K/AKT/mTOR pathway. The addition of LY294002 reversed the tumor growth induced by BCAT1 overexpression, further verifying this mechanism. CONCLUSION: BCAT1 might act as an oncogene by facilitating proliferation, invasion, and angiogenesis through activation of the PI3K/AKT/mTOR pathway. This finding could aid the optimization of antiangiogenesis strategies.

Alpha-enolase (ENO1), identified as an antigen to monoclonal antibody 12C7, promotes the self-renewal and malignant phenotype of lung cancer stem cells by AMPK/mTOR pathway.

BACKGROUND: Tumor-associated antigens (TAAs) can be targeted in cancer therapy. We previously identified a monoclonal antibody (mAb) 12C7, which presented anti-tumor activity in lung cancer stem cells (LCSCs). Here, we aimed to identify the target antigen for 12C7 and confirm its role in LCSCs. METHODS: Immunofluorescence was used for antigen localization. After targeted antigen purification by electrophoresis and immunoblot, the antigen was identified by LC-MALDI-TOF/TOF mass spectrometry, immunofluorescence, and immunoprecipitation. The overexpression or silence of ENO1 was induced by lentiviral transduction. Self-renewal, growth, and invasion of LCSCs were evaluated by sphere formation, colony formation, and invasion assay, respectively. High-throughput transcriptome sequencing (RNA-seq) and bioinformatics analysis were performed to analyze downstream targets and pathways of targeted antigen. RESULTS: Targeted antigen showed a surface antigen expression pattern, and the 43-55 kDa protein band was identified as α-enolase (ENO1). Self-renewal, growth, and invasion abilities of LCSCs were remarkably inhibited by ENO1 downregulation, while enhanced by ENO1 upregulation. RNA-seq and bioinformatics analysis eventually screened 4 self-renewal-related and 6 invasion-related differentially expressed genes. GSEA analysis and qRT-PCR verified that ENO1 regulated self-renewal, invasion-related genes, and pathways. KEGG pathway analysis and immunoblot demonstrated that ENO1 inactivated AMPK pathway and activated mTOR pathway in LCSCs. CONCLUSIONS: ENO1 is identified as a targeted antigen of mAb 12C7 and plays a pivotal role in facilitating self-renewal, growth, and invasion of LCSCs. These findings provide a potent therapeutic target for the stem cell therapy for lung cancer and have potential to improve the anti-tumor activity of 12C7.

Enolase 1 regulates stem cell-like properties in gastric cancer cells by stimulating glycolysis.

Recent studies have demonstrated that gastric cancer stem cells (CSCs) are a rare sub-group of gastric cancer (GC) cells and have an important role in promoting the tumor growth and progression of GC. In the present study, we demonstrated that the glycolytic enzyme Enolase 1 (ENO1) was involved in the regulation of the stem cell-like characteristics of GC cells, as compared to the parental cell lines PAMC-82 and SNU16, the expression of ENO1 in spheroids markedly increased. We then observed that ENO1 could enhance stem cell-like characteristics, including self-renewal capacity, cell invasion and migration, chemoresistance, and even the tumorigenicity of GC cells. ENO1 is known as an enzyme that is involved in glycolysis, but our results showed that ENO1 could markedly promote the glycolytic activity of cells. Furthermore, inhibiting glycolysis activity using 2-deoxy-D-glucose treatment significantly reduced the stemness of GC cells. Therefore, ENO1 could improve the stemness of CSCs by enhancing the cells' glycolysis. Subsequently, to further confirm our results, we found that the inhibition of ENO1 using AP-III-a4 (ENOblock) could reduce the stemness of GC cells to a similar extent as the knockdown of ENO1 by shRNA. Finally, increased expression of ENO1 was related to poor prognosis in GC patients. Taken together, our results demonstrated that ENO1 is a significant biomarker associated with the stemness of GC cells.

[Clinical study of autoantibody spectrum against ovarian cancer associated antigens combined with CA(125) in detecting and monitoring ovarian cancer].

OBJECTIVE: To evaluate the clinical value of autoantibody spectrum against ovarian cancer associated antigens combine CA(125) in detecting and monitoring ovarian cancer. METHODS: Circulating IgG, IgM autoantibodies against ovarian cancer associated antigens which included TM4SF1, C1D, TIZ, OV-142, FXR1 and OV-189 were measured by indirect ELISA in serum from 126 patients with ovarian cancer (prior treatment), 42 patients with benign ovarian masses, 142 healthy women. Cut off value of IgG, IgM autoantibodies were determined by receive operating characteristic (ROC) curve. CA(125) was measured in serum by immunoradiometric assay (IRMA). We evaluated the clinical value of combining multiple autoantibodies (autoantibody spectrum), combining autoantibody spectrum with CA(125) by binary logistic regresion. The positive ratio of autoantibody spectrum in serum (prior and post treatment) of 24 synchronization patients with ovarian cancer was analyzed to evaluate the value in monitoring state of illness. RESULTS: Our data indicated that serum contains IgG, IgM autoantibodies against ovarian cancer associated antigens. The positive ratio of IgG autoantibodies in serum from ovarian cancer patients and cancer-free patients were 34.1% - 47.6% and 13.0% - 19.0%, respectively (P < 0.05). The positive ratio of IgM autoantibodies in serum from ovarian cancer patients and cancer-free patients were 39.7% - 53.2% and 12.0% - 33.2%, respectively (P < 0.05). The positive ratio of IgG autoantibodies against FXR1 and IgM autoantibodies against TIZ, FXR1 and OV-189 in early stage (I-II) ovarian cancer (55.3%, 63.8%, 61.7% and 66.0%) were significantly higher than those in advanced (III-IV) ovarian cancer (34.2%, 39.2%, 26.6%, 45.6%; all P < 0.05). Combining five autoantibodies (TM4SF1 IgG, TM4SF1 IgM, C1D IgG, FXR1 IgG and TIZ IgM) showed significantly improved sensitivity (75.4%, P < 0.05), lower specificity (78.3%, P < 0.05) and similar accuracy (77.1%, P > 0.05) in detecting ovarian cancer compared to those of CA(125) (61.1%, 88.0%, 77.1%). But the autoantibody spectrum showed significantly improved sensitivity in classifying early stage (76.6%), compared to those of CA(125) (51.1%, P < 0.05). Combining autoantibody spectrum with CA(125) showed significantly improved sensitivity (85.7%), specificity (90.8%)and accuracy (88.7%) in detecting ovarian cancer compared to those of autoantibody spectrum alone (all P < 0.05), while CA(125) (61.1%, P < 0.05; 88.0%, P > 0.05; 77.1%, P < 0.05). The positive ratio of combine the autoantibody spectrum with CA(125) was significantly lower in 24 post-treatment serum (42%) compared to the pairing prior treatment serum (88%, P < 0.05). CONCLUSION: Combining the autoantibody spectrum against ovarian cancer associated antigens with CA(125) can improve sensitivity, specificity and accuracy in detecting early ovarian cancer and may be used to monitoring state of illness.

Secreted LOXL2 is a novel therapeutic target that promotes gastric cancer metastasis via the Src/FAK pathway.

The purpose of this study was to investigate invasion- and metastasis-related genes in gastric cancer. To this end, we used the transwell system to select a highly invasive subcell line from minimally invasive parent cells and compared gene expression in paired cell lines with high- and low-invasive potentials. Lysyl oxidase-like 2 (LOXL2) was overexpressed in the highly invasive subcell line. Immunohistochemical analysis revealed that LOXL2 expression was markedly increased in carcinoma relative to normal epithelia, and this overexpression in primary tumor was significantly associated with depth of tumor invasion, lymph node metastasis and poorer overall survival. Moreover, LOXL2 expression was further increased in lymph node metastases compared with primary cancer tissues. RNA interference-mediated knockdown and ectopic expression of LOXL2 showed that LOXL2 promoted tumor cell invasion in vitro and increased gastric carcinoma metastasis in vivo. Subsequent mechanistic studies showed that LOXL2 could activate both the Snail/E-cadherin and Src kinase/Focal adhesion kinase (Src/FAK) pathways. However, secreted LOXL2 induced gastric tumor cell invasion and metastasis exclusively via the Src/FAK pathway. Expression correlation analysis in gastric carcinoma tissues also revealed that LOXL2 promoted invasion via the Src/FAK pathway but not the Snail/E-cadherin pathway. We then evaluated secreted LOXL2 as a target for gastric carcinoma treatment and found that an antibody against LOXL2 significantly inhibited tumor growth and metastasis. Overall, our data revealed that LOXL2 overexpression, a frequent event in gastric carcinoma progression, contributes to tumor cell invasion and metastasis, and LOXL2 may be a therapeutic target for preventing and treating metastases.

[Clinical evaluation of autoantibody of splice variant of BARD1 in detection of ovarian cancer].

OBJECTIVE: To investigate the value of autoantibody of breast cancer susceptibility 1-associated RING domain (BARD1) splice variant (OV-142) in detection of ovarian cancer. METHODS: We cloned OV-142 gene into plasmid pET-30b(+). The recombinant protein of OV-142 was expressed in pET-30b(+) system and purified. The autoantibody of OV-142 was detected by indirect enzyme-linked immunosorbent assay (ELISA). RESULTS: We successfully constructed the recombinant plasmid of OV-142. The recombinant protein was expressed in pET-30b(+) system and purified. The purification rate of the recombinant protein was up to 90%. The relative amount of autoantibody of OV-142 detected by indirect ELISA was analyzed by receiver operating characteristic curve (ROC) and the cutoff value was determined. Combination of the autoantibody IgG of OV-142 and CA(125) was analyzed by logistic regression. The sensitivity, specificity and accuracy was 71.4%, 89.1%, and 81.9%, respectively, which were higher than IgG (41.3%, 84.2%, 66.8%) and CA(125) (61.1%, 88.0%, 77.1%) when used alone each. CONCLUSIONS: OV-142 is a splice variant of BARD1. It may be a potential immunotherapy target of ovarian cancer. Detection of autoantibody of OV-142 is a potent complementary tool of CA(125) in ovarian cancer diagnosis.

TM4SF3 promotes esophageal carcinoma metastasis via upregulating ADAM12m expression.

Esophageal cancer is characterized by rapid clinical progression and poor prognosis due to adjacent tissue invasion and distant organs metastasis at a very early stage. TM4SF3 (transmembrane 4 superfamily 3), a member of tetraspanin family, has been reported as a metastasis associated gene in many types of tumors. Herein, we described new properties of TM4SF3 in tumor metastasis, which suggested that this gene might be involved in esophageal carcinoma metastasis. Western blotting revealed that TM4SF3 was overexpressed in 57.1% (8/14) of esophageal carcinomas and esophageal carcinoma cell lines with high-invasive potential. Exogenous expression of TM4SF3 in two low-invasive esophageal carcinoma cell lines, KYSE150 and EC9706, significantly promoted cell migration and invasion. Upregulating TM4SF3 expression in EC9706 cells promoted xenograft tumor invading into surrounding tissues, enhanced lung metastasis, and shortened the lifespan of mice (median survival EC9706-TM4SF3 106.5 days versus EC9706-Vector 169.0 days, P < 0.0001) in a spontaneous metastasis model. Further studies demonstrated that ADAM12m was upregulated by TM4SF3 overexpression in vitro and in vivo. Abrogating up-expression of ADAM12m by siRNA significantly suppressed TM4SF3-mediated invasion. Together, these data from our studies indicated that overexpression of TM4SF3 in esophageal cancer conferred advantage to the invasion and metastasis of this destructive disease. Upregulated expression of ADAM12m by TM4SF3 might play a key role in TM4SF3-mediated invasion and metastasis. TM4SF3 and ADAM12m might be potential targets of esophageal carcinoma for anti-metastasis therapy.

[In vivo effect of annexin I down-regulation on the growth of human pancreatic cancer in nude mice].

OBJECTIVE: To further explore the effect of annexin I on the tumor growth of human pancreatic cancer in nude mice. METHODS: To knock down the expression of annexin I in pancreatic carcinoma cells by RNAi. A nude mouse model of human pancreatic cancer was established by subcutaneous inoculation of human pancreatic cancer cell line Suit-II cells. The effect of annexin I on tumor growth was assessed by tumor growth curve and tumor weight records, and Westen blot and flow cytometry were used to examine the expression of annexin I after annexin I-knocking down. RESULTS: The results of Western blot revealed that the expression of annexin I was significantly decreased in Suit-II cells transfected with pSilencer-annexin I-siRNA1, and almost completely inhibited in the cells transfected with pSilencer-annexin I-siRNA2 and pSilencer-annexin I-siRNA3. The growth of tumors transfected with annexin I-siRNA2 and annexin I-siRNA3 was inhibited by 76.6% and 68.4%, respectively, in comparison with that of tumor from the parent Suit-II cells. At 44 days after tumor cell inoculation, the tumor weight was 0.8987 g (transfected with annexin I-siRNA2) and 0.8992 g (transfected with annexin I-siRNA3), significantly lower (P < 0.001) than that of tumor from parent Suit-II cells (2.5866 g) and transfected with annexin I-siRNAN (2.4070 g). CONCLUSION: annexin I promotes the growth and proliferation of pancreatic carcinoma cells in vivo and increases the ability of tumor formation in nude mice. The results of this study support that annexin I may become a potential target in gene therapy for this disease.

[Preparation of functional antibodies targeting tumor endothelia for the treatment of hepatic carcinoma].

BACKGROUND & OBJECTIVE: Tumor growth relies on angiogenesis; angiogenic inhibition can effectively treat tumors. This study was to develop monoclonal antibody library against human hepatic carcinoma vessel endothelial cells (HCVECs), and screen functional monoclonal antibodies with inhibitory effect on the angiogenesis of hepatic carcinoma. METHODS: Endothelial cells were separated from human hepatic carcinoma tissue to immunize 10 BALB/c mice. The spleen cells of the immunized mice were fused with SP2/0 cells and cultured on methyl cellulose. Functional monoclonal antibodies of each clone were screened by immunofluorescence, endothelial cell proliferation assay, tube formation assay, and humanized blood vessel in vivo tumor model. RESULTS: A total of 1,442 monoclonal antibody clones were obtained by fusing spleen cells with SP2/0 cells; 119 clones could specifically react with HCVECs. Of the 119 clones, 53 significantly suppressed the proliferation or tube formation of HCVECs. Two of the 53 monoclonal antibody clones suppressed the hepatic tumor growth in vivo, with inhibitory rates of 66.7% and 76.5%. CONCLUSION: We successfully developed 2 functional monoclonal antibodies which could suppress the hepatic tumor growth in vivo.

[Human esophageal carcinoma antigens screened by serologic analysis of recombinant cDNA expression libraries (SEREX)].

BACKGROUND & OBJECTIVE: In malignant transformation, mutant gene products and dysregulated proteins can become tumor antigens and activate immunoreactions. Therefore, auto-antibodies exist in sera of cancer patients. Serologic analysis of recombinant cDNA expression libraries (SEREX) using autologous and allogenic patient sera provides a powerful approach to identify tumor antigens. This study was to identify esophageal cancer antigens with SEREX for serologic diagnosis, gene therapy, and immune therapy. METHODS: Expression library of cDNA from esophageal squamous cell carcinoma was constructed. SEREX screened out 21 positive clones from the 1.6x10(6) clones in the established library. The 21 positive clones were subcloned to monoclonality and submitted to in vivo excision of pBluescript phagemids. The nucleotide sequences of cDNA inserts were analyzed with DNASIS and BLAST software on EMBL and GenBank. According to the bioinformatics analyses, serologic immunoreactions of 4 colons in 10 samples of esophageal cancer serum and 10 samples of normal control serum were further detected by SADA. RESULTS: Of the 21 positive clones, 4 had no homology to any known genes, 17 were known fragments which were defined as antigens of esophageal cancer for the first time. The serologic immunoreaction rates of 4 selected antigens, including Ribosomal protein S4, and so on, were 40%, 60%, 70%, and 30%, respectively, in cancer sera, and 0%, 10%, 20%, and 20%, respectively, in normal sera. CONCLUSIONS: Antigens, such as Ribosomal protein S4, are frequently involved in serologic immunoreactions of esophageal cancer. The 21 antigens identified by the present study can be used as potential targets for gene therapy and serologic biomarkers of esophageal cancer.

[Screening and sero-immunoscreening of ovarian epithelial cancer associative antigens].

OBJECTIVE: To explore epithelial ovarian cancer (EOC) antigens that are potentially useful for cancer early detection and therapy. METHODS: A high quality cDNA library derived from ascites tumor cells of EOC patients (3 cases of serous EOC, 1 case of mucinous EOC, and 1 case of endometrial carcinoma of ovary) was constructed, and the method of combining serological analysis of recombinant cDNA expression libraries (SEREX) and suppression subtractive hybridization (SSH) was used for screening cDNA library. All of the positive clones were sequenced and bioinformatics analysis with BLAST software in GenBank was performed. Serological mini-arrays of recombinant tumor antigens (SMARTA) was used to investigate the prevalence of autoantibodies to these antigens in both 96 ovarian cancer patients and 96 cancer-free controls. RESULTS: Fifty-five positive clones encoding different antigenic genes of EOC recognized by IgG and (or) IgM were obtained. It showed that these 55 clones derived from 45 distinct genes and these genes could be grouped into 6 classes as following according to homology with known expressed sequence tag (EST): (1) known ovarian carcinoma related genes: BARD1, et al; (2) homologous genes with other tumors: TM4SF1, et al; (3) homologous genes with special tissues: ILF3, FXR1, et al; (4) homologous genes with special function: TIZ, C1D, et al; (5) embryo originating genes: PKHD1, et al; (6) novel genes: OV-189, et al. SMARTA results showed that the positive ratio of five EOC antigens TM4SF1 (28% vs. 9%), C1D (21% vs. 6%), BARD1 (23% vs. 5%), FXR1 (23% vs. 8%), OV-189 (31% vs. 13%) which reacting with their IgG autoantibodies, three antigens TIZ (26% vs. 8%), FXR1 (28% vs. 11%), and OV-189 (18% vs. 7%) which reacting with their IgM autoantibodies in patients was higher than in controls (P < 0.05). The positive ratio of EOC antigens FXR1 (34% vs. 16%), and OV-189 (46% vs. 23%) reacting with their IgG autoantibodies and TIZ (40% vs. 18%), FXR1 (46% vs. 18%) which reacting with their IgM autoantibodies in stage I-II patients was higher than that in stage III-IV (P < 0.05). The positive ratio of OV-189 (67% vs. 26%) which reacting with its IgG autoantibodies in well differentiated cases was higher than in moderately-poorly differentiated cases (P < 0.01). Combination of the above antigens showed a 66% sensitivity and 73% accuracy in discriminating EOC. Combination of the autoantibody profile of TM4SF1, C1D, TIZ, BARD1, FXR1, OV-189 with CA125 showed an 83% sensitivity and 80% accuracy in discriminating EOC. CONCLUSIONS: The strategy of combination of SEREX and SSH is a potent tool in isolating tumor-associated antigen genes. Autoantibody profile of TM4SF1, C1D, TIZ, BARD1, FXR1, OV-189 are potential tumor markers in EOC detection.

[Establishment and application of engrafted tumor models with humanized tumor blood vessel].

BACKGROUND & OBJECTIVE: Animal models are indispensable in the studies of tumor endothelial genes and anti-angiogenic therapy. This study was to build a new engrafted tumor model with humanized blood vessels. METHODS: Human liver sinusoid endothelial cells (HLSECs) were mixed respectively with human liver cancer cell line BEL7402, human colon cancer cell line LS174T, and human esophageal cancer cell line NEC, and then inoculated into NOD/SCID mice or BALB/c nude mice. The mice inoculated with only tumor cells were used as controls. Tumor growth was observed. Green fluorescent protein (GFP)-labeled HLSECs were observed under fluorescent microscope to detect their survival and tube formation. Microvessel density (MVD) was analyzed by immunohistochemistry. The tumor-bearing mice were treated by anti-HLSEC monoclonal antibody 2B6 to observe its effect on tumor growth. RESULTS: Tumor growth was significantly enhanced by the co-inoculation of HLSECs with BEL7402 cells in NOD/SCID mice; tumor weight was increased by 5.1 folds as compared with that of control. GFP-labeled vessels could easily be observed in the tumors from co-inoculation of HLSECs with BEL7402 cells. Total MVD was increased by 85.7% of control. The humanized MVD was about 10.28-29.28, which was 41%-65% of total MVD. Furthermore, the co-inoculation of HLSECs with NECs, BEL7402, or LS174T cells in nude mice led to 3.3-6.0 folds increase of xenograft weight as compared with control. When treated with 2B6 antibody, humanized MVD was decreased by 65.1% in the engrafted tumors and the tumor weight lost 71.8%. CONCLUSIONS: When co-inoculate with human tumor cell lines into mice, HLSECs could survive, proliferate, and contribute to tumor angiogenesis, which may enhance tumor growth. The engrafted tumor in vivo model with humanized vessels can be widely used in the research of functional genes in tumor angiogenesis and anti-angiogenic therapies.

Overexpressed Derlin-1 inhibits ER expansion in the endothelial cells derived from human hepatic cavernous hemangioma.

Proteins that are unfolded or misfolded in the endoplasmic reticulum (ER) must be targeted for refolding or degradation to maintain the homeostasis of the ER. Derlin-1 was reportedly implicated in the retro-translocation of misfolded proteins from the ER to the cytosol for degradation. In this report, we showed that Derlin-1 was down-regulated in the endothelial cells derived from human hepatic cavernous hemangioma (CHEC) compared with other tested cells. Electron microscopy analysis showed that ER was aberrantly enlarged in CHEC cells, but not in other tested cells. When overexpressed, Derlin-1 induced the dilated ER to return normal size. This ER dynamic was associated with the activation of unfolded protein response (UPR). In CHEC cells where Derlin-1 was down-regulated, increased expression of the immunoglobulin heavy chain-binding protein (Bip) and UPR-specific splicing of X-box DNAbinding protein 1 (XBP1) mRNA were detected, as compared with that in other tested cells, indicating that UPR was activated. After Derlin-1 overexpression, the extent of UPR activation diminished, as evidenced by decreased expression of Bip, reduced amount of the spliced form of XBP1 (XBP1s), and elevated expression of the unspliced form of XBP1 (XBP1u). Taken together, these findings provide another example of a single protein being able to affect ER dynamic in mammalian cells, and an insight into the possible molecular mechanism(s).

Construction of human liver cancer vascular endothelium cDNA expression library and screening of the endothelium-associated antigen genes.

AIM: To gain tumor endothelium associated antigen genes from human liver cancer vascular endothelial cells (HLCVECs) cDNA expression library, so as to find some new possible targets for the diagnosis and therapy of liver tumor. METHODS: HLCVECs were isolated and purified from a fresh hepatocellular carcinoma tissue sample, and were cultured and proliferated in vitro. A cDNA expression library was constructed with the mRNA extracted from HLCVECs. Anti-sera were prepared from immunized BALB/c mice through subcutaneous injection with high dose of fixed HLCVECs, and were then tested for their specificity against HLCVECs and angiogenic effects in vitro, such as inhibiting proliferation and inducing apoptosis of tumor endothelial cells, using immunocytochemistry, immunofluorescence, cell cycle analysis and MTT assays, etc. The identified xenogeneic sera from immunized mice were employed to screen the library of HLCVECs by modified serological analyses of recombinant cDNA expression libraries (SEREX). The positive clones were sequenced and analyzed by bio-informatics. RESULTS: The primary cDNA library consisted of 2 x 10(6) recombinants. Thirty-six positive clones were obtained from 6 x 10(5) independent clones by immunoscreening. Bio-informatics analysis of cDNA sequences indicated that 36 positive clones represented 18 different genes. Among them, 3 were new genes previously unreported, 2 of which were hypothetical genes. The other 15 were already known ones. Series analysis of gene expression (SAGE) database showed that ERP70, GRP58, GAPDH, SSB, S100A6, BMP-6, DVS27, HSP70 and NAC alpha in these genes were associated with endothelium and angiogenesis, but their effects on HLCVECs were still unclear. GAPDH, S100A6, BMP-6 and hsp70 were identified by SEREX in other tumor cDNA expression libraries. CONCLUSION: By screening of HLCVECs cDNA expression library using sera from immunized mice with HLCVECs, the functional genes associated with tumor endothelium or angiogenesis were identified. The modified SEREX, xenogeneic functional serum screening, was demonstrated to be effective for isolation and identification of antigen genes of tumor endothelium, and also for other tumor cell antigen genes. These antigen genes obtained in this study could be a valuable resource for basic and clinical studies of tumor angiogenesis, thus facilitating the development of anti- angiogenesis targeting therapy of tumors.

[High expression of human angiogenesis inhibitor HIAF-1 in insect cells and biological activity].

BACKGROUND & OBJECTIVE: Human inhibiting angiogenesis factor-1(HIAF-1) expressed in E coli. shown the activity of inhibiting the angiogenesis of tumors. This study was designed to investigate the expression of HIAF-1 in insect cells and to elucidate its biological activity. METHODS: Recombinant baculovirus expression vector pAcuW51-HIAF-1 was constructed by recombinant DNA technique and cotransfected with linearized baculovirus DNA into sf9 cells to produce recombinant virus. The expression of recombinant HIAF-1 in insect cells infected by recombinant virus was detected by SDS-PAGE and Western blot. The recombinant protein was purified by affinity chromatography. In vitro endothelial proliferation inhibiting activity of recombinant HIAF-1 was examined by MTT method, its antitumor activity in vivo was studied in human esophageal cancer transplanted in nude mice. RESULTS: HIAF-1 was effectively expressed in insect cells as 26 KD fusing protein and its expression level was about 5-10% of insect cellular total soluble proteins. Recombinant HIAF-1 protein could inhibit endothelial cell proliferation in vitro with IC50 value of 3.1 micrograms/ml and inhibited remarkably growth of human esophageal cancer transplanted in nude mice. CONCLUSIONS: The recombinant HIAF-1 with better activity was successfully expressed in insect cells and establish a base for clinical application.