zerumbone and Carcinoma--Renal-Cell

Persistent activation of signal transducer and activator of transcription 3 (STAT3) is one of the characteristic features of renal cell carcinoma (RCC) and often linked to its deregulated proliferation, survival, and angiogenesis. In the present report, we investigated whether zerumbone, a sesquiterpene, exerts its anticancer effect through modulation of STAT3 activation pathway. The pharmacological effect of zerumbone on STAT3 activation, associated protein kinases and phosphatase, and apoptosis was investigated using both RCC cell lines and xenograft mouse model. We observed that zerumbone suppressed STAT3 activation in a dose- and time-dependent manner in RCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src, Janus-activated kinase 1, and Janus-activated kinase 2. Pervanadate treatment reversed zerumbone-induced downregulation of STAT3, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that zerumbone induced the expression of tyrosine phosphatase SHP-1 that correlated with its ability to inhibit STAT3 activation. Interestingly, deletion of SHP-1 gene by siRNA abolished the ability of zerumbone to inhibit STAT3 activation. The inhibition of STAT3 activation by zerumbone also caused the suppression of the gene products involved in proliferation, survival, and angiogenesis. Finally, when administered i.p., zerumbone inhibited STAT3 activation in tumor tissues and the growth of human RCC xenograft tumors in athymic nu/nu mice without any side effects. Overall, our results suggest for the first time that zerumbone is a novel blocker of STAT3 signaling cascade and thus has an enormous potential for the treatment of RCC and other solid tumors.

Topics: Animals; Apoptosis; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Proliferation; Female; Humans; Janus Kinase 1; Janus Kinase 2; Kidney Neoplasms; Mice; Mice, Nude; Neovascularization, Pathologic; Protein Tyrosine Phosphatase, Non-Receptor Type 6; Sesquiterpenes; Signal Transduction; src-Family Kinases; STAT3 Transcription Factor

Renal cell carcinoma (RCC) is a malignant disease insensitive to conventional treatments such as radiochemotherapy and immunotherapy. Search for new approaches to induce cancer cell apoptosis will improve the management of RCC. Here, we reported that zerumbone, a monosesquiterpine, shows anticancer effects on human RCC cells via induction of apoptosis in vitro. Human renal clear cell carcinoma 786-0 and 769-P cell lines were used as the model system. Exposure of RCC cells to zerumbone resulted in cell viability inhibition, accompanied by DNA fragmentation and increased apoptotic index. Mechanically, treatment of RCC cells with zerumbone activated caspase-3 and caspase-9, and finally led to cleavage of PARR In addition, downregulation of Gli-1 and Bcl-2, which were closely related to the chemoresistance of RCC, was observed in zerumbone-treated RCC cells. Taken together, our study provided the first evidence that zerumbone imparted strong inhibitory and apoptotic effects on human RCC cells. The zerumbone-induced apoptosis might be related to the activation of the caspase cascade and deregulation of the Gli-1/Bcl-2 pathway. Our results suggest that zerumbone merit further investigation as an apoptosis inducer as well as a novel RCC chemotherapeutic agent in the clinical setting.

Topics: Apoptosis; Blotting, Western; Carcinoma, Renal Cell; Caspases; Cell Line, Tumor; Cell Survival; Cyclin D1; DNA Fragmentation; Enzyme Activation; Flow Cytometry; Humans; Oncogene Proteins; Sesquiterpenes; Signal Transduction; Trans-Activators; Zinc Finger Protein GLI1