Our data suggests that the specific downregulation of Mcl-1 by RNAi is a promising approach to induce apoptosis and enhance the chemosensitivity for pancreatic carcinoma gene therapy.

No abstract

The currently used vaccine against tuberculosis, Bacille Calmette‐Guérin (BCG), has variable efficacy, so new vaccine development is crucial. In this study, we evaluated a recombinant vaccine prepared from non‐pathogenic Mycobacterium smegmatis (rMS) that expresses a fusion of early secreted antigenic target 6‐kDa antigen (ESAT6) and culture filtrate protein 10 (CFP10). C57BL/6 mice were immunized with the rMS expressing the ESAT6‐CFP10 fusion protein (rM.S‐e6c10) or with BCG. The mice in the rM.S‐e6c10 group had a significantly higher titre of anti‐ESAT6‐CFP10 antibodies than did animals in the BCG or saline groups. Spleen cells from rM.S‐e6c10‐immunized mice exhibited a cytotoxic response to ESAT6 and CFP10‐expressed target cells, but spleen cells from animals in the other groups did not. Levels of IFN‐γ and IL‐2 production by purified T cells from spleens were significantly higher in rM.S‐e6c10 group than in BCG group. Finally, after M. tuberculosis (MTB)‐challenged mice, dramatic reduction in the numbers of MTB colony‐forming units (CFUs) in the lungs was observed for the mice immunized with the rMS. The protective efficacy of rM.S‐e6c10 and BCG vaccination was similar based on measures of MTB burden and lung pathology. Our data indicate that the recombinant M. smegmatis vaccine expressing the ESAT6‐CFP10 fusion protein has potential in clinic application.

Stathmin (Oncoprotein18), a signal transduction regulatory factor, plays an important role in cell division and malignant tumor development. Stathmin is a ubiquitous intracellular phosphoprotein that is overexpressed in a variety of human malignancies, including osteosarcoma. To investigate the potential use of stathmin as a therapeutic target for human osteosarcomas, we employed RNA interference [small interfering RNA (siRNA)] to reduce stathmin expression in human osteosarcoma cell lines and analyzed their phenotypic changes. Results showed that the downregulation of stathmin expression in human osteosarcoma cells significantly inhibited cell proliferation in vitro and tumorigenicity in vivo. The specific downregulation induced cell arrest in the G 2 /M phase of cell cycle and eventually apoptotic cell death. Taxanes are a group of effective chemotherapeutic agents whose activity is mediated through stabilization of the microtubules of the mitotic spindle. In the present study, we also observed a synergistic enhancement of the cytotoxicity effect by combination use of taxanes and RNA interference-mediated stathmin downregulation. All these experimental data indicate that stathmin downregulation can lead to potent antitumor activity and chemosensitizing activity to taxanes in human osteosarcomas.

No abstract

Cabazitaxel has been used to treat castration-resistant prostate cancer since its approval by the US Food and Drug Administration in 2010. However, whether cabazitaxel may inhibit the proliferation of other tissue-derived cancer cells, and its underlying mechanism, remains unknown. In the present study, the A549 lung adenocarcinoma cancer cell line was exposed to cabazitaxel, in order to investigate its cytotoxic effect and determine the underlying mechanism. The results demonstrated that cabazitaxel was able to induce autophagy in A549 cells, as evidenced by the formation of autophagosomes, upregulated LC3-II expression and increased LC3 puncta. Cabazitaxel-induced autophagy had a cytotoxic effect on A549 cells, as evidenced by the induction of cell death and cell cycle arrest at G2/M phase, which was independent of the apoptotic pathway. Furthermore, transfection with Beclin1 small interfering RNA and treatment with the autophagy inhibitor 3-methyladenine protected cells from cabazitaxel-induced cell death, thus confirming that cabazitaxel-induced autophagy contributed to A549 cell death. In addition, cabazitaxel targeted the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway to induce autophagy, as indicated by reduced phosphorylation of Akt and mTOR. In conclusion, the present study demonstrated that cabazitaxel exerts a cytotoxic effect on A549 cells by acting on the PI3K/Akt/mTOR pathway to promote autophagic cell death. This result supports the potential use of cabazitaxel as a chemotherapeutic agent for the treatment of lung cancer.

Human telomerase is a ribonucleoprotein complex composed of two subunits, an RNA component (hTR) and a human telomerase reverse transcriptase component (hTERT). The activation of telomerase, a process regulated by the human telomerase reverse transcriptase (hTERT), is a crucial step during cellular immortalization and malignant transformation. hTERT is overexpressed in most malignant cells but undetectable in most normal somatic cells. To explore its possibility as a therapeutic target for human cervical carcinoma, we developed a novel tumor-specific RNA interference system targeting hTERT by using the survivin promoter and investigated the effects of it on the proliferation, apoptosis and radiosensitivity in human cervical carcinoma cells (HeLa). The treatment of HeLa cells by hTERT gene RNAi not only could inhibit the proliferation of human cervical carcinoma cells (HeLa), but also could enhance the radiosensitivity of those cells via downregulation of their mRNA and protein expression. Therefore, survivin promoter-driven siRNA expression vector targeting hTERT may have potential use in radiosensitization therapy with targeted tumor gene silencing effect in human cervical carcinomas.

No abstract