ZIA BC 011095 (ZIA) | |||
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Title | Hypoxia and Tyrosine Kinase Signaling Integration in Urologic Cancers | ||
Institution | NCI, Bethesda, MD | ||
Principal Investigator | Bottaro, Donald | NCI Program Director | N/A |
Cancer Activity | N/A | Division | CCR |
Funded Amount | $200,076 | Project Dates | 00/00/0000 - 00/00/0000 |
Fiscal Year | 2016 | Project Type | Intramural |
Research Topics w/ Percent Relevance | Cancer Types w/ Percent Relevance | ||
Cancer (100.0%) Metastasis (50.0%) |
Kidney Disease (100.0%) Urinary System (100.0%) Kidney Cancer (100.0%) |
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Research Type | |||
Cancer Initiation: Oncogenes & Tumor Suppressor Genes Systemic Therapies - Discovery and Development |
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Abstract | |||
Aim 1: Synergistic invasion in type 1 papillary RCC driven by HGF and hypoxia signaling. HGF signaling contributes to disease progression, tumor invasiveness and metastasis in kidney cancers other than the clear cell type; in particular, MET kinase domain mutations in a hereditary form of papillary renal carcinoma (PRC) are primary drivers of that disease, and Met overabundance is common in both hereditary and sporadic forms. VHL loss of function is rare in PRC, but tumor hypoxia is not; hypoxia strongly enhances HGF-mediated invasiveness and metastasis in a variety of model systems, through largely undefined molecular mechanisms. Nonetheless, HGF-driven beta-catenin transcriptional activity is suppressed when VHL is functional, suggesting that the integration of hypoxia and HGF driven cell invasiveness in PRC involves other primary signaling routes. Indeed, we found that convergence of the mitogen-activated protein kinase (MAPK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and reactive oxygen species (ROS) signaling pathways mediate synergistic invasiveness triggered by HGF and hypoxia in several PRC cell lines, which further entailed induction of autophagy and growth suppression. Hypoxia induced ROS accumulation suppressed DUSP2 expression, thereby enhancing ERK activation. ROS also triggered a cascade of phospholipase C-gamma activation, diacylglycerol production and protein kinase C-mediated phosphatase 2A activation which suppressed HGF-induced Akt activation and cell cycle progression while promoting autophagy. Akt suppression and the consequent shift from HGF-enhanced, proliferation-oriented metabolism to autophagy proved to be required for synergistic invasion. This tripartite signaling integration was not unique to RCC or HGF: in RCC cells, invasive synergy induced by the combination of hypoxia and EGF occurred through the same mechanism, and in ER positive breast cancer cells, this mechanism was suppressed in the absence of estrogen. These results define the molecular basis of growth factor and hypoxia invasive synergy in VHL-competent papillary RCC cells, illustrate the plasticity of invasive and proliferative tumor cell states and provide signaling profiles by which they may be predicted. Aim 2: The experimental therapeutic AR-12 targets proteostasis machinery in clear cell RCC. Various evidence suggests that PI3K/AKT1 and mTOR pathways may be aberrantly activated in larger subpopulations of all RCC subtypes than the reported frequencies of mutation or epigenetic suppression of key components such as PIK3CA and PTEN in TCGA datasets suggest. This, evidence of positive feedback loops from mTOR inhibition to PI3K/AKT1 signaling, and evidence of AKT1-independent signaling downstream of oncogenic PI3K activation, provide a rationale for identifying additional critical nodes in survival pathways for therapeutic targeting in RCC. Since PDPK1 (PDK-1, protein kinase B) is a key regulator of both AKT1-dependant and -independent survival pathways, PDPK1 inhibition is a compelling potential therapeutic strategy. We studied the potential efficacy of PDPK1 inhibition in ccRCC using both siRNA knockdown and pharmacological suppression by AR-12 (OSU-03012), a novel PDPK1 agent developed by Dr. Ching-Shih Chen (The Ohio State University) and then in early clinical development through Arno Therapeutics. AR-12 was obtained through an MTA. While studying ccRCC cell sensitivity to AR-12, we uncovered evidence that the drug was acting independently of PDPK1. The findings were extraordinary given the effort by various research groups that had brought the compound to phase I clinical trials. Nonetheless, we followed a logical route to identify its actual mechanism(s) of action using kinase assays, DTP COMPARE software to infer activity, and with the help of Dr. Chen's lab to immobilize AR-12 on a solid phase, by capturing putative targets from cell lysates that were then identified by mass spectrometry. Among the latter list of |