SANJEEV GUPTA | bioRxiv Science

bioRxiv2016

Reduced CREB3L2 expression is associated with resistance to sorafenib and poor prognosis in ER-positive breast cancer

Sorafenib is a multikinase inhibitor that acts by inhibiting tumour growth and disrupting tumour microvasculature through anti-proliferative, anti-angiogenic, and pro-apoptotic effects. However, development of resistance to sorafenib often prevents its long-term efficacy. No validated biomarkers currently exist for appropriately selecting patients with cancer for sorafenib treatment. In the present study, we report that CREB3L2 expression in human breast cancer cell lines is a marker of response to sorafenib. Analysis of human breast cancer cell lines using Oncomine database and Genomics of Drug Sensitivity in Cancer (GDSC) database revealed an association between reduced expression of CREB3L2 and sensitivity to sorafenib. Wet lab experiment in five human breast cancer cell lines confirmed the association between reduced expression of CREB3L2 and sensitivity to sorafenib. Further, reduced expression of CREB3L2 was associated with poor Reccurence Free Survival in Luminal breast cancer. Our results suggest that CREB3L2 expression is a biomarker of response to sorafenib and outcome in breast cancer.

Cancer Biology↗

bioRxiv2015

Loss of Dicer1 in mouse embryonic fibroblasts impairs ER stress-induced apoptosis

BackgroundThe endoplasmic reticulum (ER) is the site of folding for membrane and secreted proteins. Accumulation of unfolded or misfolded proteins in the ER triggers the unfolded protein response (UPR). The UPR can promote survival by reducing the load of unfolded proteins through upregulation of chaperones and global attenuation of protein synthesis. However, when ER stress is acute or prolonged cells undergo apoptosis. In this study we sought to determine the effect of globally compromised microRNA biogenesis on the UPR and ER stress-induced apoptosis\n\nResultsHere we report the role of Dicer-dependent miRNA biogenesis during the UPR and ER stress-induced apoptosis. We show that ER stress-induced caspase activation and apoptosis is attenuated in Dicer deficient fibroblasts. ER stress-mediated induction of GRP78, the key ER resident chaperone, and also HERP, an important component of ER-associated degradation, are significantly increased in Dicer deficient cells. Expression of the BCL-2 family members BIM and MCL1 were significantly higher in Dicer-null fibroblasts. However, ER stress-mediated induction of pro-apoptotic BH3 only protein BIM was compromised in Dicer mutant cells.\n\nConclusionsThese observations demonstrate key roles for Dicer in the UPR and implicate miRNAs as critical components of UPR.

Cell Biology↗