Amplification and overexpression of Aurora-A in esophageal squamous cell carcinoma.

Aurora-A/BTAK/STK15 gene which encodes a centrosome-associated kinase is located on chromosome 20q13.2, a highly amplified region in various human tumors. Recent studies have demonstrated the overexpression and amplification of Aurora-A in many malignant human cancers. The purpose of this study was to investigate the amplification and expression of Aurora-A in esophageal squamous cell carcinoma. Amplification of Aurora-A was determined by fluorescence in situ hybridization in 7 esophageal cancer cell lines and real-time PCR in 29 esophageal cancer samples. We detected Aurora-A expression in 7 esophageal cancer cell lines and 38 esophageal cancers samples by semi-quantitative reverse transcription-PCR and Western blot hybridization. The amplification of Aurora-A was detected in 27 of 29 (93.1%) esophageal cancer samples and 6 of 7 (85.7%) cancer cell lines. Aurora-A was overexpressed in 27 of 38 (71.1%) esophageal cancer samples and all 7 esophageal cancer cell lines. We conclude that Aurora-A is amplified and overexpressed in esophageal squamous cancer.

[Expression of survivin and its significance in esophageal cancer].

OBJECTIVE: To detect the expression of survivin in esophageal cancer and elucidate its function in esophageal cancer. METHODS: Expression of surviv in was detected in paired normal and tumor tissues from patients with esophageal cancer by semi-quantitative RT-PCR. A dominant-negative survivin (surT34A) was transfected into esophageal cancer EC9706 cells (EC9706surT34A). Colony formation and apoptosis of the parental and surT34A-transfected EC9706 cells were examined in soft agar and by flow cytometry, respectively. RESULTS: Survivin mRNA expression of tumor tissues was higher than normal tissues in 18/27 (66.7%) samples. The expression level of survivin mRNA in tumor tissues (2.08 +/- 1.32) was significantly higher than that in normal tissues (1.22 +/- 1.09). EC9706 surT34A cells formed fewer colonies on agar than the non-transfected ones. After serum withdrawal, EC9706surT34A had higher apoptotic ratio than control, but survivin could reduce the apoptotic ratio. CONCLUSION: Overexpression of survivin is a common eventin esophageal cancer. The dominant-negative survivin can partially inhibit the malignant phenotype of esophageal cancer.

Knockdown of c-Myc expression by RNAi inhibits MCF-7 breast tumor cells growth in vitro and in vivo.

INTRODUCTION: Breast cancer is the leading cause of cancer death in women worldwide. Elevated expression of c-Myc is a frequent genetic abnormality seen in this malignancy. For a better understanding of its role in maintaining the malignant phenotype, we used RNA interference (RNAi) directed against c-Myc in our study. RNAi provides a new, reliable method to investigate gene function and has the potential for gene therapy. The aim of the study was to examine the anti-tumor effects elicited by a decrease in the protein level of c-Myc by RNAi and its possible mechanism of effects in MCF-7 cells. METHOD: A plasmid-based polymerase III promoter system was used to deliver and express short interfering RNA (siRNA) targeting c-myc to reduce its expression in MCF-7 cells. Western blot analysis was used to measure the protein level of c-Myc. We assessed the effects of c-Myc silencing on tumor growth by a growth curve, by soft agar assay and by nude mice experiments in vivo. Standard fluorescence-activated cell sorter analysis and TdT-mediated dUTP nick end labelling assay were used to determine apoptosis of the cells. RESULTS: Our data showed that plasmids expressing siRNA against c-myc markedly and durably reduced its expression in MCF-7 cells by up to 80%, decreased the growth rate of MCF-7 cells, inhibited colony formation in soft agar and significantly reduced tumor growth in nude mice. We also found that depletion of c-Myc in this manner promoted apoptosis of MCF-7 cells upon serum withdrawal. CONCLUSION: c-Myc has a pivotal function in the development of breast cancer. Our data show that decreasing the c-Myc protein level in MCF-7 cells by RNAi could significantly inhibit tumor growth both in vitro and in vivo, and imply the therapeutic potential of RNAi on the treatment of breast cancer by targeting overexpression oncogenes such as c-myc, and c-myc might be a potential therapeutic target for human breast cancer.

Detection of human papillomavirus in Chinese esophageal squamous cell carcinoma and its adjacent normal epithelium.

AIM: To investigate the putative role of human papillomavirus (HPV) infection in the carcinogenesis of esophageal squamous cell carcinoma in China. METHODS: Twenty-three esophageal squamous cell carcinoma samples and the distal normal epithelium from Shanxi Province, and 25 more esophageal squamous cell carcinoma samples from Anyang city, two areas with a high incidence of esophageal cancer in China, were detected for the existence of HPV-16 DNA by PCR, mRNA in situ hybridization (ISH) and immunohistochemistry (IHC) targeting HPV-16 E6 gene. RESULTS: There were approximately 64 % (31/48) patients having HPV-16 DNA in tumor samples, among them nearly two-thirds (19/31) samples were detected with mRNA expression of HPV-16 E6. However, in the normal esophageal epithelium from cancer patients, the DNA and mRNA of HPV-16 were found with much less rate: 34.7 % (8/23) and 26.1 % (6/23) respectively. In addition, at protein level detected by IHC assay, 27.1 % (13/48) tumor samples had virus oncoprotein E6 expression, while only one case of normal epithelium was found positive. CONCLUSION: HPV infection, especially type 16, should be considered as a risk factor for esophageal malignancies in China.

[Survivin mutants reverse the malignancy of HeLa cells].

BACKGROUND & OBJECTIVE: Survivin was aberrantly expressed in most cancer tissues, suggesting that survivin plays an important role in carcinogenesis. This study was designed to investigate the function and mechanism of survivin mutants in tumor cells. METHODS: The site-mutant and truncated survivin mutants were transfected into HeLa cells and selected using G418. Cell apoptosis was analyzed using flow cytometry. Protein level of cyclin D1 was detected by Western blot analysis. RESULTS: Survivin mutant plasmid expressed in the HeLa cells successfully. The expressed protein could be detected using related antibody. Colony formation ability significantly decreased in the HeLa cells with survivin mutants compared with that in the parental HeLa cells. The HeLa cells transfected instantly with survivin mutants could undergo apoptosis automatically. Meanwhile, survivin mutants could cause an increase of multinuclear HeLa cells. The effect of survivin-N showed more effective than that of survivin T34A. Survivin-N and survivin T34A could influence the expression of cyclin D1 and reduced its protein levels of 68% and 12%, respectively. CONCLUSION: Survivin mutants can partially reverse the malignancy of HeLa cells. The reduction of cyclin D1 induced by survivin mutants may play an important role in it. Survivin may be a target gene in gene therapy of cancer.

[Expression and significance of beta-catenin in esophageal carcinoma].

BACKGROUND & OBJECTIVE: Many reports have characterized the aberrant expression of beta-catenin in diverse types of human cancer. To determine whether beta-catenin has possible roles in esophageal carcinogensis, we designed this study to detect the expression pattern of beta-catenin in normal esophageal epithelium and esophageal cancer tissue, then to study the relevance of its expression and localization to tumor differetiation degree and lymph node metastasis. METHODS: By using immunohistochemical staining(SP method), the expression of beta-catenin was detected in 22 normal esophageal tissue slides and 52 esophageal carcinomas. RESULTS: In the 22 normal esophageal tissue, beta-catenin showed high intense expression at the membrane and low intense expression at the cytoplasm. In contrast to the normal tissue, beta-catenin was expressed in the cytoplasma in carcinoma with varied degrees, accompanied by less, or even lost expression at the membrane in cancer samples. In some cases, beta-catenin could be detected in the nucleus. Moreover, the positive rate of beta-catenin expression in cytoplasm was significantly higher in those patients with lymph node metastasis than patients without(P < 0.05). CONCLUSIONS: The aberrant expression of beta-catenin occurred frequently in the esophageal carcinoma, mainly including the translocation of beta-catenin protein from membrane to the cytoplasm and nucleus, and the accumulation of beta-catenin in cytoplasma was overt. And the aberrant expression of beta-catenin protein was statistically correlated to the lymph node metastasis in esophageal cancer.