Down-regulation of Bcl-X_L by RNA interference suppresses cell growth and induces apoptosis in human esophageal cancer cells

AIM: To determine the inhibitory effect of the vector- generated small interfering RNAs (siRNAs) on the expression of the Bcl-XL gene in established human esophageal cancer cells, and to investigate the effect of the Bcl-XL siRNAs on cell growth and apoptosis in esophageal cancer cells. METHODS: Three siRNA-expressing vectors targeting different sites of the Bcl-XL gene were constructed from pTZ-U6+1 vector. Cultured esophageal cancer cells were transfected with the siRNA-expressing vector (or the control vector) using lipofectamine 2000. Bcl-XL gene expression was determined with semiquantitative RT- PCR assay and Western blotting. Among the three siRNA- expressing vectors, the most highly functional vector and its effect on cell growth and apoptosis in esophageal cancer cells was further analyzed. RESULTS: Of the three siRNA-expressing vectors, siRNA- expressing vector No.1 was the most potent one which suppressed Bcl-XL mRNA production to 32.5% of that in the untreated esophageal cancer cells. Western blotting analysis showed that siRNA-expressing vector No.1 markedly down-regulated the expression of Bcl-XL in human esophageal cancer cells. Treatment of esophageal cancer cells with siRNA-expressing vector No.1 resulted in inhibition of cell growth and induction of apoptosis. CONCLUSION: Down-regulation of Bcl-XL by vector- generated small interfering RNAs can suppress cell growth and induce apoptosis in human esophageal cancer cells.

Evaluation of the Protective Efficacy of a Fused OmpK/Omp22 Protein Vaccine Candidate against Acinetobacter baumannii Infection in Mice

Acinetobocter baumannfi （A. Baumannii） is an emerging opportunistic pathogen responsible for hospital-acquired infections, and which now constitutes a sufficiently serious threat to public health to necessitate the development of an effective vaccine. In this study, a recombinant fused protein named OmpK/Omp22 and two individual proteins OmpK and Omp22 were obtained using recombinant expression and Ni-affinity purification. Groups of BALB/c mice were immunized with these proteins and challenged with a clinically isolated strain of A. boumonnii. The bacterial load in the blood, pathological changes in the lung tissue and survival rates after challenge were evaluated. Mice immunized with OmpK/Omp22 fused protein provided significantly greater protection against A. boumonnfi challenge than those immunized with either of the two proteins individually. The results provide novel clues for future design of vaccines against A. boumonnii.

Overexpression of Annexin A2 Is Associated with Abnormal Ubiquitination in Breast Cancer

Abnormal expression of annexin A2 contributes to metastasis and infiltration of cancer cells. To elucidate the cause of abnormal expres- sion of annexin A2, Western blotting, immunoproteomics and immunohistochemical staining were performed to analyze differentially ubiquitinated proteins between fresh breast cancer tissue and its adjacent normal breast tissue from five female volunteers. We detected an ubiquitinated protein that was up-regulated in the cancer tissue, which was further identified as annexin A2 by mass spectrometry. These results suggest that abnormal ubiquitination and/or degradation of annexin A2 may lead to presence of annexin A2 at high level, which may further promote metastasis and infiltration of the breast cancer cells.