Abstract 203: Regenerable altruism drives chemotolerance in clonal cancer cells

Abstract

Introduction: Cancer is thought to represent a breakdown of multicellular cooperation and reversion to Darwinian dynamics characterized principally by self-interested competition. However, there is increasing evidence that cancer cells can behave as communities, manifesting social behaviors that influence cancer progression. Methods: Circulating tumor cells enrichment, microRNA extraction, qRT-PCR, MTS assays, RNA in situ hybridization, immunohistochemical staining, SILAC-based mass spectrometry, flow cytometry, ChIP-sequencing, and western blotting. Results: We report here evidences of altruistic cooperation in clonal breast cancer cells. Heterogeneity in expression of a microRNA, miR-125b, leads to sectoring of clonal breast cancer cell populations into minority miR-125b-high and majority miR-125b-low subpopulations. Enhanced population-wide tolerance to taxane-based chemotherapy is mediated by the miR-125b-high minority, in part through increased secretion of extracellular public goods such as insulin-like growth factor binding protein 2 (IGFBP2) and chemokine (C-C motif) ligand 28 (CCL28). Cost-benefit analysis established this helping behavior to be altruistic, as survival benefits conferred to the miR-125b-low cells, via public goods sharing, occurred at a fitness cost to the miR-125b-high cells. Notwithstanding this fitness cost, miR-125b-high altruists regenerate readily from isolated populations of miR-125b-low defectors, via Kruppel-like factor 2-mediated epigenetic mechanism of histone deacetylation. As therapeutic proof-of-principle, we demonstrated that targeting extracellular IGFBP2 and CCL28, through ligand neutralization, markedly blunted the tolerance response of cancer cells towards taxane chemotherapy. Conclusions: Our results demonstrate how positive social engagement such as altruism may be employed by heterogeneous clonal cancer communities to drive chemotolerance, and understanding of such social behaviors could help formulate more effective treatment strategies. Citation Format: Kee Wah Lee, Muhammad Sufyan Masroni, Karen Meiling Tan, Mo-Huang Li, Lihan Zhou, Steven Tucker, Lynette Su Mien Ngo, Chan Fong Chang, Boon Huat Bay, Soo Yong Tan, Mikael Hartman, Huiwen Chua, Tze Ping Loh, Thomas Putti, Sai Mun Leong, Evelyn Siew-Chuan Koay. Regenerable altruism drives chemotolerance in clonal cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 203.