A novel causal model for nasopharyngeal carcinoma.

The development of nasopharyngeal carcinoma (NPC) and its unique geographic distribution have long been attributed to a combination of dietary intake of salt-preserved fish, inherited susceptibility, and early-life infection with the Epstein-Barr virus (EBV). New findings from our large, rigorously designed, population-based case-control study of NPC in southern China have enabled substantial revision of this causal model. Here, we briefly summarize these results and provide an updated model of the etiology of NPC. Our new research identifies two EBV genetic variants that may be causally involved in the majority of NPC in southern China, and suggests the rise of modern environmental co-factors accompanying cultural and economic transformation in NPC-endemic regions. These discoveries can be translated directly into clinical and public health advances, including improvement of indoor air quality and oral health, development of an EBV vaccine, enhanced screening strategies, and improved risk prediction. Greater understanding of the roles of environmental, genetic, and viral risk factors can reveal the extent to which these agents act independently or jointly on NPC development. The history of NPC research demonstrates how epidemiology can shed light on the interplay of genes, environment, and infections in carcinogenesis, and how this knowledge can be harnessed for cancer prevention and control.

Synergistic effects ofα-Fe2O3nanoparticles and Fe-doping on gas-sensing performance of NiO nanowires and interface mechanism.

High surface area nickel oxide nanowires (NiO NWs), Fe-doped NiO NWs andα-Fe2O3/Fe-doped NiO NWs were synthesized with nanocasting pathway, and then the morphology, microstructure and components of all samples were characterized with XRD, TEM, EDS, UV-vis spectra and nitrogen adsorption-desorption isotherms. Owing to the uniform mesoporous template, all samples with the same diameter exhibit the similar mesoporous-structures. The loadedα-Fe2O3nanoparticles should exist in mesoporous channels between Fe-doped NiO NWs to form heterogeneous contact at the interface of n-typeα-Fe2O3nanoparticles and p-type NiO NWs. The gas-sensing results indicate that Fe-dopant andα-Fe2O3-loading both improve the gas-sensing performance of NiO NWs sensors.α-Fe2O3/Fe-doped NiO NWs sensors presented the highest response to 100 ppm ethanol gas (55.264) compared with Fe-doped NiO NWs (24.617) and NiO NWs sensors (3.189). The donor Fe-dopant increases the ground state resistance and the absorbed oxygen content in air.α-Fe2O3nanoparticles in electron depletion region result in the increasing resistance in ethanol gas and decreasing resistance in air. In this way,α-Fe2O3/Fe-doped NiO NWs sensor presents the excellent gas-sensing performance due to the formation of heterogeneous contact at the interface.

[Susceptibility genes and risk prediction model of cardiovascular toxicity related to antineoplastic therapy in tumor patients].

Cardiovascular toxicity of cancer patients in antineoplastic therapy is gradually paid widespread attention. Although many high-risk factors of cardiovascular toxicity associated with chemotherapy, targeted therapy or immunotherapy have been identified, it is still difficult to establish accurate risk prediction model. Traditional risk prediction model cannot adequately explain the differences in cardiovascular toxicity susceptibility among patients, makes it difficult to accurately screen high-risk groups, early diagnose and prevent cardiovascular toxicity. Finding susceptible genes of cardiovascular toxicity associated with antineoplastic therapy and incorporating single-nucleotide polymorphisms into risk prediction model can significantly improve the identification of high-risk population of cardiovascular toxicity.

[Expression of anaplastic lymphoma kinase fusion gene in patients with lung sarcomatoid carcinoma and treatment analysis].

Objective: To investigate the expression status of anaplastic lymphoma kinase (ALK) fusion gene in lung sarcomatoid carcinoma (LSC) and the role of ALK inhibitors for treatment. Methods: Total of 84 cases of LSC confirmed by histopathology were detected for ALK fusion gene from January 2011 to December 2014 in the Cancer Hospital of Chinese Academy of Medical Science&Peking Union Medical College and Shandong Zibo Wanjie Cancer Hospital. All patients were primarily treated by the multi-disciplinary mode in combination with chemotherapy or targeted therapy based on surgery. Postoperative adjuvant chemotherapy was given on platinum based two-drug combination regimen. In ALK fusion gene (+ ) patients with recurrence or metastasis, crizotinib target therapy was prefered. Chi-square test was applied for the comparison of 1, 3, 5-year survival rates between the two groups. Results: Eighty-two cases completed the follow-up. ALK fusion gene was found in 9(10.7%) patients. After application of crizotinib, 1 case was evaluated as complete remission, 6 cases as partial response, 2 cases as stable disease; the 1, 3, 5-year survival rate was 100% (9/9), 100% (9/9) and 88.9% (8/9) for the patients with ALK fusion gene, and it was 65.8% (48/73), 15.1% (11/73) and 6.8% (5/73) respectively for patients without ALK fusion gene. There was significant difference in the survival rate between the two groups (χ(2)=1.56, 1.56, 0.83, all P<0.05). Conclusion: ALK fusion gene maybe expressed in LSC patients. Compared with conventional chemotherapy, crizotinib can significantly prolong the survival time of patients with ALK fusion gene.

[Analysis of treatment and prognosis in post-operative patients with urachal carcinoma].

OBJECTIVE: Urachal carcinoma is a kind of urogenital tract malignancy with a very low incidence. The objective of this study was to observe the clinical presentation, pathological condition, treatment method and outcome of patients with urachal carcinoma. METHODS: A retrospective analysis of thirty-six cases of urachal carcinoma diagnosed over a period of 10 years from 2003 to 2013 was carried out. All pathologic specimens were reviewed by two separate pathologists. Clinical and histological features, treatment condition, patient follow-up and survival outcome was reviewed and calculated. RESULTS: The mean age at diagnosis was 53 years. Of the thirty-six patients, twenty-five were male. All patients underwent partial cystectomy with bilateral pelvic lymph node dissection. All cases were adenocarcinoma, including 20 mucinous adenocarcinoma, 7 moderately differentiated adenocarcinoma, 5 poorly differentiated adenocarcinoma, 1 signet ring cell carcinoma, 3 hybrid adenocarcinoma. The Sheldon pathologic stage was stage Ⅱ in 11, Ⅲ in 16 and Ⅳa in 9 cases. All patients received medical oncological therapy. The median follow-up period was 27 months. The median overall survival was 36 months. One-year survival rate was 70% and five-year survival rate was 28%. CONCLUSIONS: Urachal carcinomas are rare and usually at locally advanced stage at diagnosis with a high tendency of metastases. Surgery is a key method of primary treatment and medical oncological therapy may play a role in decreasing the chances of recurrence which still needs to be explained by prospective clinical trials.

Mapping quantitative trait loci for sheath blight disease resistance in Yangdao 4 rice.

Rice sheath blight (ShB), which is caused by Rhizoctonia solani, has become the most serious rice disease in China. Yangdao 4, a cultivar with partial resistance to ShB, was crossed with Lemont, a susceptible cultivar, to develop mapping populations that were used to analyze quantitative trait loci (QTL) that confer resistance to ShB. QTL analysis were performed in 3 environments (E1-E3) using 2 F2 and 1 F2:3 populations, respectively. Three traits were recorded to evaluate ShB resistance, including disease rating (DR), lesion height (LH), and percentage of lesion height (PLH). Based on field evaluation of ShB resistance and the 2 genetic maps constructed, we identified a total of 8 QTLs for DR (4 in E1, 4 in E2, and 3 in E3), 6 QTLs for LH (1 in E1, 3 in E2, and 2 in E3), and 7 QTLs for PLH (1 in E1, 4 in E2, and 2 in E3). Sixteen of the ShB-QTLs co-localized as 6 clusters on chromosomes 3, 7, 11, and 12. Four of the 6 clusters contained ShB-QTLs that were detected in 2 environments, while the other 2 clusters with ShB-QTLs were detected in 1 environment. Three ShB-QTLs (qSBD-3-2, qSBL-3-1, and qSBPL-3-1) were delimited to a 581-kb region flanked by markers D333B and D334 on chromosome 3. The resistance alleles of Yangdao 4 at the qSBD-3-2 locus decreased DR by 0.68 and 0.79 in E2 and E3, respectively.

MiR-29c mediates epithelial-to-mesenchymal transition in human colorectal carcinoma metastasis via PTP4A and GNA13 regulation of ß-catenin signaling.

BACKGROUND: Distant metastasis is the major cause of cancer-related death, and epithelial-to-mesenchymal transition (EMT) has a critical role in this process. Accumulating evidence indicates that EMT can be regulated by microRNAs (miRNAs). miR-29c has been implicated as a tumor suppressor in several human cancers. However, the role of miR-29c in the progression of colorectal cancer (CRC) metastasis remains largely unknown. PATIENTS AND METHODS: The expression of miR-29c was examined by qRT-PCR in a cohort of primary CRC (PC) and distant liver metastasis (LM) tissues. A series of in vivo and in vitro assays were carried out in order to elucidate the functions of miR-29c and the molecular mechanisms underlying the pathogenesis of metastatic CRC. RESULTS: miR-29c was markedly downregulated in PCs with distant metastasis and determined to be an independent predictor of shortened patient survival. But LM tissues showed higher levels of miR-29c than that in PC tissues. In CRC cells, miR-29c dramatically suppressed cell migration and invasion abilities in vitro and cancer metastasis in vivo. In addition, miR-29c inhibited EMT and negatively regulated Wnt/ß-catenin signaling pathway. Guanine nucleotide binding protein alpha13 (GNA13) and protein tyrosine phosphatase type IVA (PTP4A) were identified as direct targets of miR-29c, which acted through ERK/GSK3ß/ß-catenin and AKT/GSK3ß/ß-catenin pathways, respectively, to regulate EMT. Furthermore, significant associations between miR-29c, its target genes (GNA13 and PTP4A) and EMT markers were validated in both PC and LM tissues. CONCLUSION: Our findings highlight the important role of miR-29c in regulating CRC EMT via GSK-3ß/ß-catenin signaling by targeting GNA13 and PTP4A and provide new insights into the metastatic basis of CRC.

Development of 1047 insertion-deletion markers for rice genetic studies and breeding.

In this study, a total of 1047 insertion-deletion (InDel) primer pairs distributed across the rice genome were developed and experimentally validated. The primer pairs were designed based on the InDel length polymorphisms between 93-11 (Oryza sativa ssp indica cv.) and Nipponbare (Oryza sativa ssp japonica cv.), aiming for utilization between indica and japonica rice, or between other inter-subspecific rice cultivars. The 1047 primer pairs were dispersed across all 12 of the rice chromosomes, with one InDel marker found every 371.3 kb on average. The InDel length of the markers varied from 3 to 39 bp: 88.2% of the markers contained 6 to 25 bp, only 6.2% of markers were ≤ 5 bp, and 5.6% were ≥ 26 bp. Six hundred and twenty-three (59.5%) of the 1047 InDel markers were shown to amplify well and were polymorphic between Taichung65 and IR8, and 476 (45.5%) markers were polymorphic between Lemont and Yangdao4, while 398 (38.0%) were polymorphic in both combinations. These results demonstrated that the polymerase chain reaction-based InDel markers developed in this study could be of immediate use for rice genetic studies and breeding programs.

AP2 inhibits cancer cell growth and activates p21WAF1/CIP1 expression.

The 52-kD Activator Protein (AP2) is a DNA-binding transcription factor implicated in signalling terminal differentiation. Profound developmental abnormalities have been recently observed in AP2-null mice. The molecular events by which AP2 promotes differentiation or development are, however, unknown. Increased expression of the universal cell cycle inhibitor p21WAF1/CIP1 occurs in growth-arrested terminally differentiating cells. In a search for cellular factors that could activate p21 during phorbol ester (TPA)-induced differentiation, we identified AP2 as a regulator of p21 expression. Mutagenesis of an AP2 DNA-binding site within a p21 promoter-luciferase reporter inhibited its activation by either AP2 transfection or TPA stimulation. Endogenous p21 protein levels were elevated and DNA synthesis was inhibited in AP2 versus control vector-transfected cells. Overexpression of AP2 in HepG2 human hepatoblastoma and SW480 human colon adenocarcinoma cells inhibited cell division and stable colony formation. These results link the differentiation-associated factor AP2 to negative cell cycle and growth control, possibly through p21 activation.

Overexpression of AIB1 negatively affects survival of surgically resected non-small-cell lung cancer patients.

BACKGROUND: The amplified in breast cancer 1 (AIB1) gene has been considered to play an oncogenic role in human cancers, but its clinical/prognostic significance in non-small-cell lung cancer (NSCLC) is still unclear. PATIENTS AND METHODS: The methods of immunohistochemistry and FISH were utilized to examine protein expression and amplification of AIB1 in 230 informative surgically resected NSCLCs and in 30 samples of normal lung tissues. RESULTS: Overexpression and amplification of AIB1 were found in 48.3% and 8.2% of NSCLCs, respectively. AIB1 overexpression was associated with AIB1 gene amplification and cell proliferation but not related to estrogen receptor (ER)-alpha, ER-beta, progesterone receptor or androgen receptor status. A positive correlation between AIB1 overexpression and an ascending pathologic node stage in lung adenocarcinoma (ADC) was observed (P = 0.043). Univariate survival analysis demonstrated a significant association of AIB1 overexpression with shortened patient survival, especially for those with stage III disease (P < 0.001). Importantly, AIB1 expression was evaluated as the most significant predictor for survival in multivariate analysis (hazards ratio = 2.069, P < 0.001). CONCLUSION: Overexpression of AIB1 might provide a selective advantage for lymph node metastasis of lung ADC and serve as a useful biomarker for poor prognosis for NSCLC patients.

[Epidemiological characteristics of leptospirosis in Sichuan province, 2004-2018].

Objective: To explore the epidemiological characteristics of leptospirosis in Sichuan province from 2004 to 2018, and provide evidence for the prevention and control of leptospirosis. Methods: The descriptive epidemiology analysis was conducted based on the epidemic data of leptospirosis collected from the national notifiable infectious disease reporting information system (NNIDRIS) and sentinel surveillance system in 11 areas in Sichuan from 2004 to 2018. The ArcGIS 10.2 software was used for mapping. The SaTScan 9.1.1 software was used to analyze spatiotemporal scanning and characteristics of temporal-spatial clusters of leptospirosis. Results: A total of 2 834 cases of leptospirosis, including 41 deaths, were reported in Sichuan from 2004 to 2018, and the reported morbidity rate was 0.23/100 000 and the mortality rate was 0.003/100 000. It revealed that leptospirosis had an overall downward fluctuated trend. The incidence of leptospirosis had obvious seasonality, mainly from the last ten-day of August to the end of September, 1-2 weeks later after rice harvesting time. The reported cases were mainly males, the male to female ratio of the cases was 2.05∶1. The incidence was higher in age group 50-65 years. The majority of reported cases were farmers, accounting for 82.75% (2 345/2 834), followed by students, accounting for 12.74% (361/2 834). However, rare cases in students had been reported since 2011. In recent years, the high-incidence areas were alternating between Mabian, Muchuan counties along the Yangtze River and Yilong county located in the Jialing River basin. According to the spatial-temporal descriptive analyses by SaTScan, there were two clustering areas in the province where most cases occurred (P<0.001). The average density of field rats in 11 sentinel surveillance areas was 5.44%(14 351/263 767), and the predominant field rats included Anourosorexsquamipes (69.07%), Apodemusagrarius (12.73%). Whatmore, the density of the Apodemusagrarius ranged from 4.60% to 0.19%, showing downward trend with the lowest level in 2018. The annual culture rate of Leptospira from rat kidney samples declined. During 2007-2018, the average positive rate of Leptospira antibodies in healthy people was 24.52%(3 271/13 339), and the predominant serogroup was Icterohaemorrhagiae. There was no replacement of Leptospira serogroup in recent years. Conclusions: The incidence of leptospirosis in Sichuan was extremely low during 2004-2018, and the incidence peak of leptospirosis occurred in rice harvesting period. The cases were mainly old farmers, and the high-risk areas were constantly alternating between the Yangtzi River and the Jialing River basin. Both the density and the carriage rate of Leptospira of Apodemusagrarius were low, and the predominant serogroup was Icterohaemorrhagiae. The average positive rate of leptospira antibodies in healthy people was very low.

BDNF activates TrkB/PLCγ1 signaling pathway to promote proliferation and invasion of ovarian cancer cells through inhibition of apoptosis.

OBJECTIVE: Abnormal expression and activation of tropomyosin-related kinase receptor B (TrkB) are observed in many pathological conditions, including many types of cancer. We try to explore the relationship between ovarian cancer and Brain-derived neurotrophic factor (BDNF), a ligand of TrkB. MATERIALS AND METHODS: Human ovarian cancer cell line SKOV-3 was used in this study. qPCR, immunohistochemistry, and immunoblot were used to assay BDNF and TrkB expression level. Scratch assay was used to test the cell motility, and transwell assay was used to test the cell migration ability. RESULTS: We found that BDNF promotes the proliferation and invasion of human ovarian cancer SKOV-3 cells depend on the activation of TrkB. To illuminate the downstream pathway of BDNF/TrkB, we silenced AKT1 and PLCγ1 by siRNA. The functional assay showed that activated PLCγ1 signaling pathway is necessary for the proliferation and invasion of cancer cells other than the AKT pathway. Further study showed that PLCγ1 could inhibit the apoptosis of cancer cells. CONCLUSIONS: BDNF triggers TrkB/PLCγ1 signaling pathway to promote proliferation and invasion of ovarian cancer cells through inhibition of apoptosis.

SCC-112 gene is involved in tumor progression and promotes the cell proliferation in G2/M phase.

PURPOSE: SCC-112 is a novel cell cycle-related gene and differentially expressed in cancers. Suggesting the complex role of SCC-112 might be existent in cell proliferation and tumor development. The relative research on SCC-112 has been few so far. This study is attempted to explore the role of SCC-112 in tumorigenesis. EXPERIMENTAL DESIGN: RT-PCR and western blot were performed on seven tumor-normal paired tissues and nine cell lines. Immunohistochemistry was carried out for analyzing the expression of SCC-112 in nasopharyngeal tissues. 293T and three nasopharyngeal cell lines were transfected with expression vector (pCMV-SPORT6-SCC-112) or its siRNA. Cell proliferation was examined by MTT and clone formation experiments. Immunoprecipitation determined the interacted protein of SCC-112, and FACS detected cell cycle parameter on cells treated with synchronized reagent. RESULTS: SCC-112 ( approximately 150 kDa) is up-regulated in tumor tissue as compared to the corresponding normal tissue and was detected in the tested cell lines. Overexpression of SCC-112 ( approximately 150 kDa) in 293T and three nasopharyngeal cell lines promoted cell proliferation and clone formation while downregulation of SCC-112 ( approximately 150 kDa) in these cells resulted in the opposite. Moreover, SCC-112 was found to interact with p63 and overexpression of SCC-112 up-regulated p63 expression. SCC-112 expression level positively correlated with cells in G2/M phase. CONCLUSIONS: These findings suggest that SCC-112 improve cell proliferation and contributes to tumorigenesis by interacting with p63 and promoting cell cycling. SCC-112 might be an alternative target in tumor biomarking and mechanistic investigation.

[Influence of fracture resistance of prosthesis with different thickness of ferrule restored with fiber post and resin core and crown].

Objective: To evaluate the influence of fracture resistance of endodontically treated teeth with different thickness of ferrule by mechanical fatigue test and static loading test, and so as to provide a reference for the clinical treatment planning. Methods: Fifty bovine incisors were divided into 5 groups by random number table method (n=10). Group A was the control group in which the incisors were prepared without a ferrule design (0 mm). The other four groups (B, C, D, E) were experimental groups, and the thickness of the dentin ferrule prepared for specimens in each group was 0.5, 1.0, 1.5, and 2.0 mm. The height of ferrules in all the specimens was 2 mm. Cyclic fatigue loading (2.33 Hz, 50 N) was applied on each specimen until either the specimen was dislodged/fractured or the 300 000 cycles were finished. After fatigue loading, the mode of failure was observed. Those intact specimen after fatigue loading were tested under a gradually increasing force using a universal testing machine (0.05 mm/min) until fracture occurred. The forces required to fracture and failure model was recorded. Results: The results of cyclic loading tests showed that: all specimens survived the 300 000 cycles of intermittent loading. The results of static loading tests showed that: the fracture force of A, B, C, D and E groups respectively were (226.4±67.7), (369.7±34.5), (400.7±48.2), (528.1±56.3), and (555.4±98.5) N (F=15.227, P=0.000). There was a significant difference in fracture resistance between group A and the other four groups, and between group B, C and group D, E (P<0.05). No statistical difference were found in fracture resistance among the other groups (P>0.05). There was strong correlation between the thickness of ferrule and the fracture force by Pearson correlation analysis (r=0.973, P=0.002). Conclusions: Within the limitations of this study, the following conclusions can be drawn: The different thickness of ferrule can influence the fracture resistance of the teeth, and when the height of the ferrule is 2.0 mm, the fracture force increased significantly with an increasing ferrule thickness.

Acetylcholinesterase expression mediated by c-Jun-NH2-terminal kinase pathway during anticancer drug-induced apoptosis.

It has been shown that acetylcholinesterase (AChE) expression was induced during apoptosis and the anti-sense oligonucleotides and siRNA of AChE may prevent apoptosis in various cell types. However, the mechanisms underlying AChE upregulation remain elusive. We demonstrated here that c-Jun NH2-terminal kinase (JNK) could mediate AChE expression. In this study, both etoposide and excisanin A, two anticancer agents, induced apoptosis in colon cancer cell line SW620 as determined by Annexin V staining, the cleavage of caspase-3 and the proteolytic degradation of poly (ADP-ribose) polymerase (PARP). The results showed that both the agents upregulated AChE in SW620 cells. In the meantime, JNK was also activated and the expression and phosphorylation of c-Jun increased in SW620 cells exposed to the two agents. The induced AChE mRNA and protein expression could be blocked by SP600125, a specific inhibitor of SAPK/JNK, and small interfering RNA directed against JNK1/2. Transfection with adenovirus-mediated dominant negative c-Jun also blocked the upregulation of AChE expression. Together, these results suggest that AChE expression may be mediated by the activation of JNK pathway during apoptosis through a c-Jun-dependent mechanism.

Senescence and telomere shortening induced by novel potent G-quadruplex interactive agents, quindoline derivatives, in human cancer cell lines.

Agents stabilizing G-quadruplexes have the potential to interfere with telomere replication by blocking the elongation step catalysed by telomerase or telomerase-independent mechanism and could therefore act as antitumor agents. In this study, we found that quindoline derivatives interacted preferentially with intramolecular G-quadruplex structures and were novel potent telomerase inhibitors. Treatment with quindoline derivatives reproducibly inhibited telomerase activity in human leukemia K562 cells and colon cancer SW620 cells. N'-(10H-Indolo [3,2-b] quinolin-11-yl)-N, N-dimethyl-propane-1,3-diamine (SYUIQ-5), (one of quindoline derivatives), when added to K562 and SW620 cell culture at nonacute cytotoxic concentrations, increased time of population doublings of K562 and SW620 cells, induced a marked cessation in cell growth and cellular senescence phenotype after 35 and 18 days, respectively. Growth cessation was accompanied by a shortening of telomere length, and induction of p16, p21 and p27 protein expression. However, another compound SYUIQ-7 with greater IC(50) for telomerase had no obvious cellular effect in nonacute cytotoxic concentrations. These results indicate that quindoline derivatives as novel potent G-quadruplex interactive agents induce senescence and telomere shortening in cancer cells and therefore are promising agents for cancer treatment.

Overexpression of maelstrom promotes bladder urothelial carcinoma cell aggressiveness by epigenetically downregulating MTSS1 through DNMT3B.

We have recently identified and characterized a novel oncogene, maelstrom (MAEL) from 1q24, in the pathogenesis of hepatocellular carcinoma. In this study, MAEL was investigated for its oncogenic role in urothelial carcinoma of the bladder (UCB) tumorigenesis/aggressiveness and underlying molecular mechanisms. Here, we report that overexpression of MAEL in UCB is important in the acquisition of an aggressive and/or poor prognostic phenotype. In UCB cell lines, knockdown of MAEL by short hairpin RNA is sufficient to inhibit cell growth, invasiveness/metastasis and suppressed epithelial-mesenchymal transition (EMT), whereas ectopic overexpression of MAEL promoted cell growth, invasive and/or metastatic capacity and enhanced EMT both in vitro and in vivo. We further demonstrate that MAEL could induce UCB cell EMT by downregulating a critical downstream target, the metastasis suppressor 1 (MTSS1) gene, ultimately leading to an increased invasiveness of cancer cells. Notably, overexpression of MAEL in UCB cells substantially enhanced the enrichment of DNA methyltrans-ferase (DNMT)3B and histone deacetylase (HDAC)1/2 on the promoter of the MTSS1, and thereby epigenetically suppressing the MTSS1 transcription. Downregulation of MTSS1 by MAEL in UCB cells is partially dependent on DNMT3B. Furthermore, we identify that beside the gene amplification of MAEL, miR-186 is a key negative regulator of MAEL and downregulation of miR-186 is another important mechanism for MAEL overexpression in UCBs. These data suggest that overexpression of MAEL, caused by gene amplification and/or decreased miR-186, has a critical oncogenic role in UCB pathogenesis by downregulation of MTSS1, and MAEL could be used as a novel prognostic marker and/or effective therapeutic target for human UCB.

Regulation of p21WAF1/CIP1 expression by p53-independent pathways.

The CDK-inhibitor p21WAF1/CIP1 has been implicated as a growth arrest mediator in p53-tumour suppression, cellular senescence and terminal differentiation. Cell type specific differences in p53-independent p21 expression and cell cycle arrest were found following treatment of human tumour cell lines with serum, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), or okadaic acid (OA). TPA induced p21 in ML1, K562 and HL60 leukemia cells, whereas OA induced p21 in SW480 and GM4723 carcinoma cells as well as in leukemic cells. In addition, TPA- and serum- but not OA-induced cell cycle arrest was reversed upon return of p21 to basal levels. To further investigate the mechanisms underlying p53-independent regulation of p21, the transcription inhibitor, Actinomycin D (AMD), was used to block p21 expression. The results showed a complete inhibition of p21 mRNA and protein induction by TPA or adriamycin but little effect on p21 mRNA induced by OA in the presence of AMD. These results suggested that TPA-induced p21 expression requires transcription initiation, while a post-transcriptional mechanism may be involved in OA-induction as well. Transient transfection assays with p21 promoter-luciferase reporters and TPA or OA treatment further confirmed that TPA, and to a lesser extent, OA, initiated transcription of p21. Finally, the protein kinase C inhibitor, staurosporine, was found to interfere with p21 induction and prevent cell cycle arrest following treatment with TPA but not OA, suggesting a requirement for PKC in TPA activation of p21 expression.

Signal pathway of mitogen-induced Ca2+-activated K+ currents in young and aged T-cell clones of C57BL/6 mice.

Signal transduction pathways of mitogenic plant lectin, concanavalin A (Con A)- and ionomycin (INM)-induced (Ca2+-dependent K+ currents (I(Con A) and I(INM)) have been compared in young and aged T-cell clones by using the nystatin perforated patch-clamp whole-cell recording technique. In young T-cell clones, Con A evoked a long-lasting outward current which is mediated by the activation of the Ca2+-dependent K+ channels. The Ca2+ ionophore, INM, evoked a short-lasting Ca2+-dependent outward K+ current (I(INM)). The protein tyrosine kinase (PTK) inhibitor, herbimycin A (3 x 10(-6) M), but not the G protein blocker, pertussis toxin (PTX, 500 ng ml(-1)), completely prevented the I(Con A), but did not affect the I(INM). In aged T-cell clones, Con A fails to evoke any current response, while INM evokes an outward current which is comparable to that in a young T-cell clone. It is concluded that PTK, but not PTX-sensitive G proteins, plays a critical role in mediation of the signal transduction from Con A stimulation to activation of the Ca2+-dependent K+ channels, and that an impairment of the early signal pathway, perhaps the PTK, might be involved in the mechanism of the age-related decline of the proliferative response of T-lymphocytes to mitogenic stimulation.

Abnormality in the early signal transduction pathway is responsible for the impaired proliferative response and low K+ current in a T-cell clone by stimulation with anti-CD3 antibody.

Two T-cell clones were established from young and old C57BL/6 mice, respectively. The proliferative response to anti-CD3 stimulation was significantly greater in the young (YT5) than in the old (OT13) T cell clone. However, a similar high response was observed in both T-cell clones upon stimulation with phorbol myristate acetate (PMA) and ionomycin (INM). The calcium-dependent K+ current (IK(Ca)) was recorded with the patch-clamp method in these T-cell clones. With anti-CD3 stimulation, the amplitude of the outward K+ current was significantly lower in OT13 than in YT5 cells. With stimulation with PMA and INM, however, no significant difference in IK(Ca) was obtained between the two types of cells. The level of proliferative response of T-cells to mitogens was well reflected by the amplitude of IK(Ca). Some abnormality in the early pathway of signal transduction, which led to the intracellular Ca2+ influx, appears to be responsible for the impaired proliferation of the old T-cell clone.