As solid human cancer tumors form there are a number of physiological changes that occur within the tumor itself. These changes include low oxygen levels (hypoxia) and an accumulation of lactic acid with concomitant lowered pH levels (lactic acidosis). In order to adapt to and survive in these physiological stresses, human cancer cells in solid tumors exhibit significant genetic and metabolic changes. While transcriptional responses and downstream signaling events are known in certain contexts of these stresses, a systematic genome-wide investigation of which genes are critical for cell survival in these TME stresses has not been examined. The central hypothesis of my proposal is that understanding the function of genes that modulate cell survival under TME stresses will allow for the development of treatments to specifically target cancer cells under TME stress conditions. To investigate this hypothesis, I propose applying the concept of synthetic lethality to cultured cancer cells by combining individual gene expression knockdown with the application of hypoxia or lactic acidosis. Our lab recently identified synthetically lethal genes for breast cancer cell survival under one TME stress, and so we expect that applying the concept genome-wide is likely to reveal other novel critical regulators.
Aim 1 will identify the genes that improve or reduce cellular fitness under two TME stresses on a genome-wide scale by two different screen approaches.
Aim 2 will investigate the mechanisms of specific gene candidates validated as "hits" from Aim 1. The goal of this project is to better understand how cancer cells adapt to and survive in the TME stresses. This knowledge will allow for a better understanding of the genetic changes selected by the TME and improve therapies to target solid human cancers in the future.

Public Health Relevance

Human (lung) cancers present a huge medical challenge and cause significant suffering and death among Americans. Therefore, new approaches are urgently needed to identify novel therapeutic approaches. Our research will identify how tumor cells survive and become selected under stresses present in solid cancer tumors. Since tumor cells are constantly exposed to stresses, eliminating these survival strategies may present novel opportunities to help eradicate human tumors.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Predoctoral Individual National Research Service Award (F31)
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Special Emphasis Panel (ZRG1-OBT-H (21))
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Korczak, Jeannette F
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Duke University
Schools of Medicine
United States
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Keenan, Melissa M; Liu, Beiyu; Tang, Xiaohu et al. (2015) ACLY and ACC1 Regulate Hypoxia-Induced Apoptosis by Modulating ETV4 via α-ketoglutarate. PLoS Genet 11:e1005599
Tang, Xiaohu; Keenan, Melissa M; Wu, Jianli et al. (2015) Comprehensive profiling of amino acid response uncovers unique methionine-deprived response dependent on intact creatine biosynthesis. PLoS Genet 11:e1005158
Keenan, Melissa M; Chi, Jen-Tsan (2015) Alternative fuels for cancer cells. Cancer J 21:49-55
Keenan, Melissa M; Ding, Chien-Kuang Cornelia; Chi, Jen-Tsan (2014) An unexpected alliance between stress responses to drive oncogenesis. Breast Cancer Res 16:471