Tissue-specific conditional PKCε knockout mice: a model to precisely reveal PKCε functional role in initiation, promotion and progression of cancer.

Bilal Bin Hafeez,Patricia Powers,Anne E. Griep,Louise Meske,Ashok Singh,Manorama John,Ajit K. Verma,Weixiong Zhong,Anupama Singh

doi:10.18632/oncotarget.8850

Abstract

PKCε is a transforming oncogene and a predictive biomarker of various human cancers. However, a precise in vivo link of PKCε to cancer induction, progression and metastasis remain undefined. To achieve these goals, we generated tissue specific conditional PKCε knockout mice (PKCε-CKO) using cre-lox technology. Homozygous PKCεLoxP/LoxP mice have normal body weight and phenotype. To determine what effect loss of PKCε would have on the prostate, the PKCεLoxP/LoxP mice were bred to probasin cre (PB-Cre4+) mice which express cre specifically in the prostate epithelium of postnatal mice. Western blot and immunohistochemical analyses showed reduced levels of PKCε specifically in the prostate of PKCε-CKO mice. Histopathological analyses of prostate from both PKCεLoxP/LoxP and prostate PKCε-CKO mice showed normal pathology. To determine the functional impact of prostate specific deletion of PKCε on prostate tumor growth, we performed an orthotopic xenograft study. Transgenic adenocarcinoma of the mouse prostate (TRAMP) cells (TRAMPC1, 2×106) were implanted in the prostate of PKCε-CKO mice. Mice were sacrificed at 6th week post-implantation. Results demonstrated a significant (P<0.05) decrease in the growth of TRAMPC1 cells-derived xenograft tumors in PKCε-CKO mice compared to wild type. To determine a link of PKCε to ultraviolet radiation (UVR) exposure-induced epidermal Stat3 phosphorylation, PKCεLoxP/LoxP mice were bred to tamoxifen-inducible K14 Cre mice. PKCε deletion in the epidermis resulted in inhibition of UVR-induced Stat3 phosphorylation. In summary, our novel PKCεLoxP/LoxP mice will be useful for defining the link of PKCε to various cancers in specific organ, tissue, or cells.

Highlights

PKC is a major intracellular receptor for the mouse skin tumor promoter 12-O-tetradecanoylphorbol-13-acetate
Protein kinase C epsilon (PKCε) is overexpressed in prostate cancer (PCa) spontaneously developed in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice, an autochthonous transgenic model that perfectly mimics to the human disease [12]
PKCε associates with Stat3 and this association increases with the progression of the diseases in TRAMP mice and in human PCa [12]

Summary

Introduction

PKC is a major intracellular receptor for the mouse skin tumor promoter 12-O-tetradecanoylphorbol-13-acetate. Overexpression of PKCε is sufficient to promote conversion of androgen-dependent (AD) LNCaP cells to androgenindependent (AI) variant, which rapidly initiates tumor growth in vivo in both intact and castrated athymic nude mice [16]. It has been shown that integrin signaling links PKCε to the PKB/ Akt survival pathway in recurrent prostate cancer (PCa) cells [18]. We and others have previously shown that PKCε level correlates with the aggressiveness of human PCa. PKCε is overexpressed in PCa spontaneously developed in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice, an autochthonous transgenic model that perfectly mimics to the human disease [12]. PKCε associates with Stat and this association increases with the progression of the diseases in TRAMP mice and in human PCa [12]. All of these findings suggest that PKCε is an oncogene and is involved in PCa development, aggressiveness, as well as in the emergence of AI PCa

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Results

Conclusion