Abstract P2-06-07: PRKCQ regulates taxol sensitivity of triple negative breast cancer cells via IL-6/Stat3 signaling

• Published in: Cancer research (Chicago, Ill.) Vol. 76; no. 4_Supplement; pp. P2 - P2-06-07
• Main Authors: Irie, HY, Byerly, J
• Format: Journal Article
• Language: English
• Published: 15.02.2016
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.SABCS15-P2-06-07

Abstract Background/Rationale. While some patients with triple negative breast cancer achieve long-term remission with chemotherapy, many have cancers that are chemotherapy resistant. The lack of targeted therapies for this subtype also makes some triple negative cancers difficult to treat and control. PRKCQ, a member of the novel protein kinase C family, is preferentially expressed in triple negative breast cancers compared to ER+/Luminal cancers. We previously reported that PRKCQ expression drives growth-factor independent growth, anoikis resistance and migration of breast epithelial cells. In addition, PRKCQ is required for in vivo growth of triple negative breast cancers tumor xenografts. We sought to determine if PRKCQ expression modulates sensitivity of triple negative breast cancer cells to standard of care chemotherapy and whether PRKCQ inhibition could be a strategy to induce death of chemotherapy-resistant triple negative breast cancer cells. Methods. We determined the effects of modulating PRKCQ expression, using PRKCQ cDNA or shRNA vectors, on Doxorubicin or Taxol treatment-induced effects on triple negative breast cancer cells, including those that are relatively chemotherapy resistant at baseline. We determined the mechanisms by which PRKCQ expression regulates sensitivity to Taxol. Results. Increased PRKCQ expression in MCF-10A breast epithelial cells suppresses the apoptosis-inducing effects of Doxorubicin or Taxol treatment. PRKCQ-induced Taxol resistance is dependent on PRKCQ kinase activity. PRKCQ-expressing MCF-10A cells secrete enhanced levels of IL-6, leading to the autocrine activation of Stat3; IL-6/Stat3 activation is necessary for PRKCQ-induced resistance to Taxol. Finally, downregulation of PRKCQ sensitized MDA-231-Luc cells to Taxol treatment and induced apoptosis of these cells which are relatively resistant to Taxol at baseline. Conclusions. PRKCQ regulates sensitivity to standard of care chemotherapies used in the treatment of triple negative breast cancer. IL-6/Stat3 signaling induced by PRKCQ kinase activity is responsible for resistance to the effects of Taxol treatment. Targeting PRKCQ therefore could be an attractive strategy to overcome chemotherapy resistance of a subset of triple negative breast cancers. Citation Format: Irie HY, Byerly J. PRKCQ regulates taxol sensitivity of triple negative breast cancer cells via IL-6/Stat3 signaling. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-06-07.