Relationship Between HSP70 and ERBB2 Expression in Breast Cancer Cell Lines Regarding Drug Resistance.

BACKGROUND: Heat shock protein 70 (HSP70) is known to be downstream of human epidermal growth factor receptor-2 (ERBB2), but little is known regarding the relationship between HSP70 and drug resistance mediated by ERBB2 in breast cancer. MATERIALS AND METHODS: After infecting breast cancer cells with lentivirus-mediated Lenti-ShHSP70 and Lenti-ShERBB2, we examined the expression of HSP70 and ERBB2 by real-time polymerase chain reaction and western blotting. RESULTS: Compared to the control groups, mRNA expression of HSP70 was decreased in lentivirus-infected, and western blotting indicated a concordant reduction of HSP70 protein. On the other hand, ERBB2 was significantly down-regulated by HSP70 silencing in SK-BR-3 cells at both the mRNA and protein levels. Expression of HSP70 in transfected cells was also reduced by Lenti-ShERBB2. CCK8 viability assay indicated that inhibition of HSP70 increased the sensitivity of SK-BR-3 cells to fluorouracil treatment. CONCLUSION: HSP70 affects ERBB2 and ERBB2-mediated drug-resistance in breast cancer cells.

DNA hypermethylation of the vimentin gene inversely correlates with vimentin expression in intestinal- and diffuse-type gastric cancer.

The vimentin gene is a hallmark of epithelial-to-mesenchymal transition and has been observed to be overexpressed in various types of tumor cell line and tissue. Previous studies have reported correlations between vimentin DNA methylation levels and subsequent vimentin expression levels in solid tumors, including breast and colorectal cancer; however, to the best of our knowledge, such a correlation has not been reported for gastric cancer (GC) using Lauren classification. Therefore, the present study aimed to quantify DNA methylation levels of the vimentin gene using quantitative (q) methylation-specific polymerase chain reaction (PCR) in intestinal-type GC cell lines (MKN-28, AGS and MKN-1), diffuse-type GC cell lines (SGC-7901, SNU-5 and KATO III), the GES-1 immortalized human non-neoplastic gastric epithelial cell line, as well as in tumor and paratumor normal tissue samples. Furthermore, the present study analyzed the messenger RNA expression of the vimentin gene in these cell lines and tissues by reverse transcription-qPCR. A comparison of the clinicopathological features was conducted between patients, grouped according to the Lauren classification. The present study identified that the vimentin promoter region was hypermethylated in all GC cell lines and tumor tissue samples when compared with immortalized normal gastric epithelial cells and paratumor normal tissues. In addition, vimentin promoter methylation levels were observed to be higher in intestinal-type cell lines when compared with those of diffuse-type lines and tissues. Correspondingly, vimentin expression levels were lower in intestinal-type gastric cell lines compared with those of diffuse-type cell lines and tissues, and were lowest in the non-neoplastic gastric cell line and paratumor normal tissues. Patients with diffuse-type GC were on average younger (P=0.023), and exhibited higher tumor (P=0.020), node (P=0.032) and TNM classification of malignant tumor stage (P=0.039) than those with intestinal-type GC. Following treatment of AGS cells (which demonstrated the highest methylation level of the vimentin gene) with 5-aza-2'-deoxycytidine, vimentin expression was restored significantly. Thus, the present study revealed that vimentin promoter methylation levels are inversely correlated with vimentin expression levels in GC (according to Lauren classification). High levels of methylation in the vimentin gene promoter region may be involved in carcinogenesis and the development of GC, and may provide a novel molecular classification for GC.