Downregulation of a putative tumor suppressor BMP4 by SOX2 promotes growth of lung squamous cell carcinoma.

SOX2 is a transcription factor essential for self-renewal and pluripotency of embryonic stem cells. Recently, SOX2 was found overexpressed in the majority of the lung squamous cell carcinoma (SQC), in which it acts as a lineage-survival oncogene. However, downstream targets/pathways of SOX2 in lung SQC cells remain to be identified. Here, we show that BMP4 is a downstream target of SOX2 in lung SQC. We found that SOX2-silencing-mediated inhibition of cell growth was accompanied by upregulation of BMP4 mRNA and its protein expression. Meta-analysis with 293 samples and qRT-PCR validation with 73 clinical samples revealed an inversely correlated relationship between levels of SOX2 and BMP4 mRNA, and significantly lower mRNA levels in tumor than in adjacent normal tissues. This was corroborated by immunohistochemistry analysis of 35 lung SQC samples showing lower BMP4 protein expression in tumor tissues. Cell-based experiments including siRNA transfection, growth assay and flow cytometry assay, further combined with a xenograft tumor model in mice, revealed that reactivation of BMP4 signaling could partially account for growth inhibition and cell cycle arrest in lung SQC cells upon silencing SOX2. Finally, chromatin immunoprecipitation analysis and luciferase reporter assay revealed that SOX2 could negatively regulate BMP4 promoter activity, possibly through binding to the promoter located in the first intron region of BMP4. Collectively, our findings suggest that BMP4 could act as a tumor suppressor and its downregulation by elevated SOX2 resulting in enhanced growth of lung SQC cells.

[Effects of small interfering RNA specific to stably transfected HMGA1 gene on biological characters of ovarian carcinoma cells].

OBJECTIVE: To investigate the effects of biological characters of the human ovarian cell line (OVCAR) by stable transfection short hairpin RNA into the target HMGA1 gene. METHODS: Experiments were divided into two groups: transfected the OVCAR cells with pSilence4.1-CMV-Hs plasmid as group A, while transfected OVCAR cells with pSilence4.1-CMV-Hn plasmid as group B, in which stably transfected cells were gained by antibiotic screening. The comparative expressions of HMGA1 were detected by RT-PCR and western blot. Methyl thiazolyl tetrazolium (MTT) method was applied to measure cell proliferation and at the same time, the cell growth curve was also be mapped. Vitro invasion assay was used to observe the invasion ability of the cancer cells, and the tumor growth of the nude mice inoculated of tumor cells were compared with before and after transfection. RESULTS: In group A, the expression level of mRNA and protein HMGA1 gene in OVCAR cells were remarkably reduced before and after the stable transfected with HMGA1 siRNA, in which the percents of mRNA expression were [(86.3 ± 2.7)% vs. (35.8 ± 3.1)%, P < 0.05], the expression of protein were [(68.6 ± 2.8)% vs. (22.3 ± 4.2)%, P < 0.05)]. The OVCAR cell growth in stable transfection status was more significantly decreased than that in non-transfection status (P < 0.05). In group B, there were no statistical difference in the expression of HMGA1 siRNA, protein and the cell growth between before and after transfection states (P > 0.05). The invasion cell numbers were reduced from before to after transfection state in group A [(53 ± 6) vs. (21 ± 6), P < 0.05], while there was no significant difference in group B [(51 ± 6) vs. (47 ± 8), P > 0.05]. After inoculated transfected cells into nude mice, it took (6.0 ± 0.9) days to grow the planed tumors in group A, which was much shorter than that (12.3 ± 3.9) days in group B (P < 0.05). After 5 weeks, the tumor weight and volume in group A was were significantly lower than those in group B [(0.8 ± 0.3) g vs. (2.1 ± 0.4) g, (205 ± 34) mm(3) vs. (987 ± 82) mm(3), all P < 0.05]. CONCLUSION: HMGA1 siRNA could remarkably reduce the expression of HMGA1 gene in ovarian cell and also inhabit the ovarian cell growth.

Sensitive and quantitative detection of severe acute respiratory syndrome coronavirus infection by real-time nested polymerase chain reaction.

A quantitative, real-time, nested polymerase chain reaction (PCR) method, combining the high sensitivity of nested PCR with time-saving real-time instrumentation, was developed for large-scale screening for severe acute coronavirus (SARS) coronavirus. Forty-six clinical specimens were analyzed by this method, and results were compared with those obtained by conventional, single-round, real-time reverse-transcriptase PCR (RT-PCR) performed in parallel. Of the 17 positive results, 2 identified by our method were not detected by single-round, real-time RT-PCR, which suggests that real-time nested PCR has the potential for increased sensitivity, leading to earlier detection of SARS.

Increased Cdc7 expression is a marker of oral squamous cell carcinoma and overexpression of Cdc7 contributes to the resistance to DNA-damaging agents.

Cdc7-Dbf4 kinase (Dbf4-dependent kinase, DDK) is an essential factor of DNA replication and DNA damage response (DDR), which is associated with tumorigenesis. However, Cdc7 expression has never been associated to the outcome of oral squamous cell carcinoma (OSCC) patients, and the mechanism underlying cancer cell survival mediated by Cdc7 remains unclear. The Cdc7 protein expression of 105 OSCC tumor and 30 benign tissues was examined by immunohistochemistry assay. Overall survival rates of 80 OSCC patients were measured using Kaplan-Meier estimates and the log-rank tests. Cdc7 overexpression by adenovirus system was used to scrutinize the underlying mechanism contributed to cancer cell survival upon DDR. In silico analysis showed that increased Cdc7 is a common feature of cancer. Cdc7 overexpression was found in 96 of 105 (91.4%) studied cases of OSCC patients. Patients with higher Cdc7 expression, either categorized into two groups: Cdc7 high expression (2+ to 3+) versus Cdc7 low expression (0 to 1+) [hazard ratios (HR)=2.6; 95% confidence interval (CI)=1.28-5.43; P=0.0087] or four groups (0 to 3+) [HR=1.71; 95% CI=1.20-2.44; P=0.0032], exhibited a poorer outcome. Multivariate analysis showed that Cdc7 is an independent marker for survival prediction. Overexpressed Cdc7 inhibits genotoxin-induced apoptosis to increase the survival of cancer cells. In summary, Cdc7 expression, which is universally upregulated in cancer, is an independent prognostic marker of OSCC. Cdc7 inhibits genotoxin-induced apoptosis and increases survival in cancer cells upon DDR, suggesting that high expression of Cdc7 enhances the resistance to chemotherapy.

Chemotherapeutic effects of different paclitaxel plus poldine combination methods for treatment of ovarian carcinoma.

The study aimed to evaluate the curative effects and toxicity of different paclitaxel (PTX) plus poldine chemotherapeutic combination methods for treatment of advanced ovarian carcinoma. A total of 27 patients with ovarian epithelial carcinoma were divided into four groups: A1, taxotere plus poldine intravenous chemotherapy (n=5); A2, taxotere intravenous chemotherapy combined with poldine intraperitoneal chemotherapy (n=7); B1, paclitaxel plus poldine intravenous chemotherapy (n=6); B2, paclitaxel intravenous chemotherapy combined with poldine intraperitoneal chemotherapy (n=9). Toxic side effects were observed after chemotherapy, and the short-term effects were assessed. Some 25 (25/27) cases completed a four-course treatment, the remaining two stopping halfway due to anaphylactic shock. The total effective rate for the A1 Group was 60% (3/5) and that of A2 group was 71.4% (5/7), Figuires for the B1 and B2 groups were 50% (3/6) and 66.7% (6/9), respectively. In comparisons of toxic side reactions, there were significant differences between taxotere groups and paclitaxel groups, and between intravenous chemotherapy alone groups and intravenous plus intraperitoneal combination chemotherapy groups (p<0.05). Chemotherapy of toxol plus poldine was effective in treatment of advanced ovarian cancer, the toxicities of intravenous plus intraperitoneal combination chemotherapy was lower than that of intravenous chemotherapy alone, and the heart toxicity with taxoere was lower than with paclitexal.

Upregulation of SOX9 in lung adenocarcinoma and its involvement in the regulation of cell growth and tumorigenicity.

PURPOSE: SOX9 is an important transcription factor required for development and has been implicated in several types of cancer. However, SOX9 has never been linked to lung cancer to date. Here, we show that SOX9 expression is upregulated in lung adenocarcinoma and show how it is associated with cancer cell growth. EXPERIMENTAL DESIGN: Data mining with five microarray data sets containing 490 clinical samples, quantitative reverse transcription-PCR validation assay in 57 independent samples, and immunohistochemistry assay with tissue microarrays containing 170 lung tissue cores were used to profile SOX9 mRNA and protein expression. Short interference RNA suppression of SOX9 in cell lines was used to scrutinize functional role(s) of SOX9 and associated molecular mechanisms. RESULTS: SOX9 mRNA and protein were consistently overexpressed in the majority of lung adenocarcinoma. Knockdown of SOX9 in lung adenocarcinoma cell lines resulted in marked decrease of adhesive and anchorage-independent growth in concordance with the upregulation of p21 (CDKN1A) and downregulation of CDK4. In agreement with higher SOX9 expression level in lung adenocarcinoma, the p21 mRNA level was significantly lower in tumors than that in normal tissues, whereas the opposite was true for CDK4, supporting the notion that SOX9 negatively and positively regulated p21 and CDK4, respectively. Finally, whereas SOX9-knockdown cells showed significantly attenuated tumorigenicity in mice, SOX9 transfectants consistently showed markedly stronger tumorigenicity. CONCLUSIONS: Our data suggest that SOX9 is a new hallmark of lung adenocarcinoma, in which SOX9 might contribute to gain of tumor growth potential, possibly acting through affecting the expression of cell cycle regulators p21 and CDK4.