Negative regulation of CDK6 expression by microRNA-126-5p and its influence on the proliferation and invasion of esophageal cancer cells.

The present study aimed to investigate the expression of cyclin-dependent kinase 6 (CDK6) and microRNA-126-5p (miR-126-5p) in esophageal cancer tissues and cells, and their effect on esophageal cancer cell proliferation and invasion, and to explore the potential molecular mechanisms. The relative expression levels of CDK6 and miR-126-5p in esophageal cancer tissue, paracancerous tissue, and HEEC and EC109 cells were determined and compared using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). A miR-126-5p overexpression vector was constructed and a stable EC109 cell line expressing miR-126-5p was established. The EC109 cell line was transfected with a CDK6 small interfering RNA sequence. The rate of cell proliferation was determined using the WST-8 method, and cell invasion was determined using a Transwell assay. In addition, the relative expression levels of genes were determined using RT-qPCR; the relative expression levels of proteins were determined by western blot analysis; the binding sites of CDK6 and miR-126-5p were analyzed using TargetScan software; and the interaction of CDK6 and miR-126-5p was verified using dual-fluorescence reporter gene expression. Esophageal tissues and EC109 cells expressed higher levels of CDK6 but significantly lower levels of miR-126-5p compared with adjacent tissues and HEEC cells, and their correlation coefficient between esophageal tissues and matched adjacent tissues was -7.526. The overexpression of miR-126-5p and CDK6 knockdown in the EC109 cell line inhibited cell proliferation and invasion compared with the control and NC (negative control) groups. miR-126-5p overexpression reduced the relative expression level of CDK6, and CDK6 knockdown by siRNA increased the expression of miR-126-5p. miR-126-5p regulated CDK6 expression by binding to the 3'-untranslated region of its mRNA. Overexpression miR-126-5p inhibited the proliferation and migration of esophageal cancer cells by targeting CDK6 and negatively regulating its expression. These findings contribute to the understanding of the underlying molecular mechanism of esophageal cancer.

Radiosensitivity enhancement by arsenic trioxide in conjunction with hyperthermia in the EC-1 esophageal carcinoma cell line.

OBJECTIVE: To explore the effect on radiosensitivity of arsenic trioxide (As203) in conjunction with hyperthermia on the esophageal carcinoma EC-1 cell line. METHOD: Inhibition of EC-1 cell proliferation at different concentrations of As203 was assessed using the methyl thiazolyl blue colorimetric method (MTT method), with calculation of IC50 value and choice of 20% of the IC50 as the experimental drug concentration. Blank control, As203, hyperthermia, radiotherapy group, As203 + hyperthermia, As203 + radiotherapy, hyperthermia + radiotherapy and As203 + hyperthermia + radiotherapy groups were established, and the cell survival fraction (SF) was calculated from flat panel colony forming analysis, and fitted by the 'multitarget click mathematical model'. Flow cytometry (FCM) was used to detect changes in cell apoptosis and the cell cycle. RESULTS: As203 exerted inhibitory effects on proliferation of esophageal carcinoma EC-1 cells, with an IC50 of 18.7 µmol/L. After joint therapy of As203 + hyperthermia + radiotherapy, the results of FCM showed that cells could be arrested in the G2/M phase, and as the ratio of cells in G0/G1 and S phases decreased, cell death became more pronounced. CONCLUSION: As203 and hyperthermia exert radiosensitivity effects on esophageal carcinoma EC-1 cells, with synergy in combination. Mechanistically, As203 and hyperthermia mainly influence the cell cycle distribution of EC-1 esophageal carcinoma cells, decreasing the repair of sublethal damage and inducing apoptosis, thereby enhancing the killing effects of radioactive rays.

[Analysis of prognostic factors in 68 patients with cancer of unknown primary site].

OBJECTIVE: The aim of this study was to analyze the clinical characteristics and prognostic factors in patients with cancer of unknown primary site (CUP). METHODS: The clinical and follow-up data of 68 CUP patients (46 adenocarcinoma patients, 22 squamous cell carcinoma patients), were retrospectively analyzed. Univariate and multivariate analysis were conducted to determine the correlation of survival with clinical features, tumor markers, blood test, liver function and so on. RESULTS: The median survival time of the 68 CUP patients was 123 days. The results from univariate Cox regression analysis showed that the prognostic factors were related to a performance status, presence or absence of liver metastases, the number of metastatic sites, carcinoembryonic antigen (CEA), lactate dehydrogenase (LDH), hypoalbuminemia, hypohemoglobinemia and lymphocyte count. Multivariate Cox regression analysis of the clinical factors identified that a performance status (PS) ≥ 2, liver metastasis, elevated serum carcinoembryonic antigen (CEA) and lactate dehydrogenase (LDH) levels, hypoalbuminemia (< 35 g/L) and lymphopenia (≤ 0.7 × 10(9)/L) were significant independent unfavorable predictive factors. Based on the number of the unfavorable predictive factors, we divided all the patients into three subgroups: subgroup involving 0-1 unfavorable factor, subgroup involving 2 - 3 unfavorable factors and subgroup involving 4 - 6 unfavorable factors. The median survival time was 390 days, 138 days and 77 days, respectively, in the 3 subgroups. Compared with the other two groups, the survival of the subgroup involving 0 - 1 unfavorable factor was significantly longer (P < 0.05), the survival between the subgroup involving 2 - 3 unfavorable factors and subgroup involving 4 - 6 unfavorable factors was not significantly different (P > 0.05). CONCLUSIONS: A performance status ≥ 2, liver metastasis, elevated serum carcinoembryonic antigen and lactate dehydrogenase levels, hypoalbuminemia and lymphopenia are independent unfavorable prognostic factors in patients with cancer of unknown primary site. The patients who had more than 2 unfavorable prognostic factors have a worse prognosis.