PUMA and NF-kB Are Cell Signaling Predictors of Reovirus Oncolysis of Breast Cancer

Abstract

Background and purposeReovirus is a ubiquitous RNA virus that exploits aberrant signaling pathways for its replication. The oncolytic potential of reovirus against numerous cancers under pre-clinical/clinical conditions has been documented by us and others. Despite its proven clinical activity, the underlying mechanisms of reovirus oncolysis is still not well elucidated. If reovirus therapy is to be optimized for cancer, including breast cancer patients, it is imperative to understand the mechanisms of reovirus oncolysis, especially in treatment of resistant tumour.Experimental approach and resultsIn the present study global gene expression profiling was utilized as a preliminary roadmap to tease-out pivotal molecules involved in reovirus induced apoptosis in breast cancer. Reovirus treated HTB133 and MCF7 breast cancer cells revealed transcriptional alteration of a defined subset of apoptotic genes and members of the nuclear factor-kappa B (NF-kB) family and p53 upregulated modulator of apoptosis (PUMA) were prominent. Since NF-kB can paradoxically suppress or promote apoptosis in cancer, the significance of NF-kB in reovirus oncolysis of breast cancer was investigated. Real time PCR analysis indicated a 2.9–4.3 fold increase in NF-kB p65 message levels following reovirus infection of MCF7 and HTB133, respectively. Nuclear translocation of NF-kB p65 protein was also dramatically augmented post reovirus treatment and correlated with enhanced DNA binding. Pharmacologic inhibition of NF-kB lead to oncolytic protection and significant down regulation of PUMA message levels. PUMA down regulation using siRNA suppressed reovirus oncolysis via significantly repressed apoptosis in p53 mutant HTB133 cells.ConclusionsThis study demonstrates for the first time that a prominent pathway of reovirus oncolysis of breast cancer is mediated through NF-kB and that PUMA upregulation is dependent on NF-kB activation. These findings represent potential therapeutic indicators of reovirus treatment in future clinical trials.

Integrated analysis of long non-coding RNA and mRNA expression in endometrial stromal cells induced by poly (I:C) identifies immune response genes

“…We next explored the role of these seven lncRNAs and their corresponding target genes in uterine infection and the immune response. Viral proliferation in cells triggers immediate (innate) and delayed (adaptive) immune responses [41,42]. In this study, many proven immune genes were identified, such as the cytokines, IL-1β and IL-6, and the chemokines, CCL5 and CCL2 [43].…”

Current understanding of reovirus oncolysis mechanisms

“… 39 , 42 , 43 NF-kB-dependent upregulation of proapoptotic proteins Noxa and Puma also is required for efficient apoptosis induction. 44 , 45 Expression of the tumor suppressor protein p53 is increased in the brain during reovirus infection of neonatal mice, suggesting that reovirus also can induce p53-dependent cell death. 46 …”

NF-κB Signaling in Targeting Tumor Cells by Oncolytic Viruses—Therapeutic Perspectives

“…NF-κB inhibition, in turn, resulted in oncolytic protection and downregulation of p53-upregulated modulator of apoptosis (PUMA) expression. This study suggests that in breast cancer therapy, NF-κB acts proapoptotically, mediates RV-induced oncolysis, and may serve as a predictive indicator of the sensitivity to RV treatment [ 108 ].…”