Rabbit Anti-Human STMN1 (Phospho-Ser15) polyclonal antibody

Colorectal cancer metastasis is a major cause of mortality worldwide, which may only be controlled with novel methods limiting tumor dissemination and chemoresistance. High stathmin-1 (STMN1) expression was previously established as a hallmark of colorectal cancer progression and predictor of poor survival; however, the mechanism of action is less clear. This work demonstrates that STMN1 silencing arrests tumor-disseminative cascades by inhibiting multiple metastatic drivers, and repressing oncogenic and mesenchymal transcription. Using a sensitive iTRAQ labeling proteomic approach that quantified differential abundance of 4562 proteins, targeting STMN1 expression was shown to reinstate the default cellular program of metastatic inhibition, and promote cellular adhesion via amplification of hemidesmosomal junctions and intermediate filament tethering. Silencing STMN1 also significantly improved chemoresponse to the classical colorectal cancer therapeutic agent, 5FU, via a novel caspase-6 (CASP6)-dependent mechanism. Interestingly, the prometastatic function of STMN1 was independent of p53 but required phosphorylations at S25 or S38; abrogating phosphorylative events may constitute an alternative route to achieving metastatic inhibition. These findings establish STMN1 as a potential target in antimetastatic therapy, and demonstrate the power of an approach coupling proteomics and transcript analyses in the global assessment of treatment benefits and potential side-effects. (C)2014 AACR.

Background and Aim: We have reported previously that RNA interference targeting stathmin1 (STMN1) gene in human gastric cancer cells inhibits proliferation in vitro and tumor growth in vivo. Based on these observations, in the present study, the possibility that local injection of lentivirus-delivered stathmin shRNA would induce regression of the established human gastric cancer xenograft in animal model was investigated. Methods: BALB/c nude mice were inoculated subcutaneously into the right armpit with human gastric cancer cells SGC-7901(2 x 106 cells in 200 mu L phosphate-buffered saline) to develop a xenograft model of human gastric cancer. When tumor reached suitable size, mice were randomly divided into two groups. STMN1 shRNA group (n = 6) were given local injection of lentivirus-delivered STMN1 shRNA, and the non-silencing shRNA group (n = 6) were administered with local injection of lentivirus-delivered non-silencing shRNA. Quantitative reverse transcription-polymerase chain reaction and Western blot were used to verify the knockdown of the gene expression in dissected tumor at mRNA and protein level, respectively. Results: Experimental therapy on the nude mice model bearing subcutaneous tumor of SGC-7901 cells showed that local administration of STMN1 shRNA effectively regressed the pre-established tumors. Stathmin shRNA-treated tumors were significantly regressed as compared with that of the tumor injected with non-silencing shRNA (P < 0.05). Tumor weight was significantly decreased in STMN1-treated group as compared with non-silencing shRNA group (P < 0.05). Quantitative reverse transcription-polymerase chain reaction and Western blot showed downregulation of STMN1 gene expression in STMN1 shRNA group as compared with non-silencing shRNA group (P < 0.05). Conclusion: These findings highlight the potential use of local injection of lentivirus-delivered shRNA for the treatment of early localized human gastric carcinoma.