Effects of the proapoptotic regulator Bcl-2/adenovirus EIB 19-kDa-interacting protein 3 on the chemosensitivity of human colon cancer cell lines

Preliminary evaluation for Bit1 as a potential biomarker for squamous cell carcinoma and adenocarcinoma of esophagus

Mounting evidence has demonstrated that Bit1 has been investigated as an etiological factor for certain cancers, including esophageal squamous cell carcinoma reported in our previous study, but data regarding possible roles of Bit1 in esophageal squamous cell carcinoma and esophageal adenocarcinoma remain to be elucidated. The purpose of this study was to examine whether Bit1 can be a novel diagnostic marker for the patients with esophageal squamous cell carcinoma and esophageal adenocarcinoma. The results revealed that Bit1 level in esophageal squamous cell carcinoma was significantly higher than that in esophageal adenocarcinoma tissues ( p < 0.05); notably, Bit1 level in esophageal adenocarcinoma tissues was lower than that in paired normal tissues but no difference was found ( p > 0.05). Bit1 expression patterns were completely in accordance with matrix metalloproteinase 2 and Bcl-2 in esophageal squamous cell carcinoma and esophageal adenocarcinoma. In addition, Bit1, Bcl-2, and matrix metalloproteinase 2 expression patterns in different differentiated esophageal squamous cell carcinoma were higher than those in corresponding normal esophageal tissues. Bit1 expression in poorly differentiated esophageal squamous cell carcinoma was significantly higher than that in normal esophageal tissues ( p < 0.05) but not in moderately and well-differentiated esophageal squamous cell carcinoma. Matrix metalloproteinase 2 expression patterns in poorly and moderately differentiated esophageal squamous cell carcinoma were significantly higher than those in corresponding normal esophageal tissues ( p < 0.01) but not in well-differentiated esophageal squamous cell carcinoma tissue ( p > 0.05). Bcl-2 expression patterns in various differentiated esophageal squamous cell carcinoma were higher than those in corresponding normal esophageal tissues with no statistical differences ( p > 0.05). Importantly, Bit1 expression was positively correlated with both matrix metalloproteinase 2 and Bcl-2 expression in esophageal squamous cell carcinoma and esophageal adenocarcinoma tissues ( p < 0.05). Collectively, these preliminary data support further investigation of Bit1 as an important diagnostic factor for esophageal squamous cell carcinoma and esophageal adenocarcinoma.

Implications of Bit1 and AIF overexpressions in esophageal squamous cell carcinoma

Overwhelming evidence has demonstrated that Bit1 and AIF as mitochondrial proteins are implicated in the development and progression of a variety of tumors. However, their expressions and biological functions in esophageal squamous cell carcinoma (ESCC) remain to be delineated. In the present study, we found that Bit1, AIF, and Bcl-2 levels in ESCC tissues were significantly higher than those in normal esophageal epithelial tissues and dysplasia tissues (P < 0.05). Stepwise investigation demonstrated that Bit1 and Bcl-2 levels were both tightly associated with lymphatic metastasis and TNM staging (P < 0.05), and the levels of Bit1 mRNA as well as AIF and Bcl-2 proteins were both closely related to tumor differentiation (P < 0.05), but not related to the patients' age and gender (P > 0.05). Importantly, Bit1 mRNA and protein levels in ESCC with lymphatic metastasis and TNM staging in III and IV were markedly higher than that without lymphatic metastasis and TMN staging in I and II. Further analysis showed that expression of Bit1 protein was both positively correlated with expressions of AIF and Bcl-2 proteins (r = 0.408 and 0.405, respectively; P < 0.05). Correctively, our data cited earlier suggest that Bit1 plays pivotal roles in the development and progression of ESCC, and its biological functions in ESCC may be closely associated with AIF and Bcl-2 levels.

Is mda-7/IL-24 a potential target and biomarker for enhancing drug sensitivity in human glioma U87 cell line?

Gliomas are the most common form of primary brain tumor with the highest mortality rates. Drug resistance is a major cause of treatment failure in patients with glioma. Melanoma differentiation associated gene-7/interleukin-24 (mda-7/IL-24) has been demonstrated to play an important role in drug resistance in human cancer cell lines. However, the reversing effect of mda-7/IL-24 on drug resistance of human glioma is not fully clear. Here, we investigated the effects of overexpression of the mda-7/IL-24 gene in human glioma. We established a cisplatin-resistant U87 glioma cell line and found that mda-7/IL-24 was highly correlated with drug resistance. Furthermore, we investigated the apoptotic rate, intracellular accumulation of Rhodamine-123, and expression of glutathione and P-glycoprotein. The over-expression of mda-7/IL-24 enhanced cisplatin cytotoxicity and reversal of drug resistance in glioma cells. The reversing effect of mda-7/IL-24 on drug resistance was induced mainly through the regulation of drug resistance-related genes and efflux drug pumps. Thus, mda-7/IL-24 can be used as a promising predictive biomarker and potential therapeutic target for chemotherapy in glioma.