Functional Interrogation Of The Colorectal Cancer Genome Identifies Numerous Suppressors Of Anchorage-Independent Growth

INTRODUCTION: High throughput cancer genome sequencing efforts are leading to the identification of frequently mutated genes in cancer. Unfortunately, the extreme diversity of lesions being detected presents a challenge to segment causal from coincidental mutations and to elucidate how causal lesions disrupt regulatory networks to drive cancer processes. AIMS AND METHODS: Given that a common early perturbation in solid tumor initiation is bypass of matrix-dependent proliferation restraints, we used immortalized human colonic epithelial cells (HCECs) to identify suppressors of anchorage-independent growth by conducting a soft-agar based shRNA screen within frequently mutated colorectal cancer (CRC) genes. RESULTS AND CONCLUSIONS: Remarkably, depletion of 65 of the 151 frequently CRC-mutated genes tested collaborated with K-RASV12 or TP53 knockdown to promote anchorage-independent proliferation of HCECs. These candidates fall under a variety of different signaling pathways, but in particular JNK signaling was found to be a master suppressor of anchorage-independent growth in normal HCECs. We have identified additional members of an extensive gene network specifying matrix-dependent proliferation, by constructing an interaction map of these confirmed progression suppressors with the ∼700 rare CRC-mutated genes and experimentally verifying soft-agar growth enhancement in response to depletion of these genes. Collectively, this study reveals a profound diversity of fragile nodes within a fundamental tumor suppressor network, perturbation of which leads to enhanced cell-autonomous proliferative fitness. These studies establish the importance of functionally annotating cancer genomes using biologically relevant assays. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2207. doi:10.1158/1538-7445.AM2011-2207