Unconjugated
BACKGROUND:
Upregulation of PIM kinase expression has been reported in many malignancies, suggesting that inhibition of PIM kinase activity may be an attractive therapeutic strategy. We hypothesised that inhibition of PIM kinase activity with SGI-1776, a novel small molecule inhibitor of PIM kinase activity, would reduce the viability of renal cell carcinoma (RCC) cells and enhance the activity of sunitinib.
METHODS:
Immunoblotting, qRT-PCR, and gene expression arrays were carried out to identify genes modulated by SGI-1776 treatment. The anticancer activity of SGI-1776 and sunitinib was determined by viability and apoptosis assays and in tumour xenografts in vivo.
RESULTS:
Treatment with SGI-1776 led to a decrease in phosphorylated and total c-Myc levels, which resulted in the modulation of c-Myc target genes. SGI-1776 in combination with sunitinib induced a further reduction in c-Myc levels, which was associated with enhanced anticancer activity. siRNA-mediated knockdown of c-Myc demonstrated that its expression has a key role in regulating the sensitivity to the combination of SGI-1776 and sunitinib. Importantly, the combination significantly reduced tumour burden in two RCC xenograft models compared with single-agent therapy and was very well tolerated.
CONCLUSION:
These data indicate that targeting PIM kinase signalling is a promising treatment strategy for RCC.
2011 Cancer Research UK
Tetrandrine, a bis-benzylisoquinoline alkaloid isolated from the dried root of Hang-Fang-Chi (Stephaniatetrandra S. Moore), has been reported to possess anti-cancer effects on many tumors. In this study, we investigated tetrandrine-induced apoptosis on human gastric cancer BGC-823 cells in vitro and in vivo. The results showed that tetrandrine significantly inhibited cell viability in a dose- and time-dependent manner and induced apoptosis. It increased the apoptosis; upregulation of Bax, Bak, and Bad; and downregulation of Bcl-2 and Bcl-xl in BGC-823 cells. Moreover, tetrandrine increased the activation of caspase-3 and -9, release of cytochrome c, and upregulation of apaf-1, suggesting that tetrandrine-induced apoptosis was related to the mitochondrial pathway. Meanwhile, pretreatment with the pan-caspase inhibitor z-VAD-fmk in BGC-823 cells reduced tetrandrine-induced apoptosis by blocking activation of caspases. Furthermore, tetrandrine effectively inhibited tumor growth via apoptosis induction, which was verified by immunohistochemical analysis in a nude mouse xenograft model. Taken together, we concluded that tetrandrine significantly inhibited the proliferation of gastric cancer BGC-823 cells through mitochondria-dependent apoptosis, which may play a promising role in gastric cancer therapy.