Abstract 3320: Functional RANK expression is observed in disaggregated primary human lung tumors

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Abstract The receptor activator of nuclear factor-κβ (RANK) and its ligand RANKL play a key role in the regulation of bone remodeling. RANK pathway activation has also been implicated in various aspects of lung tumor biology. In mouse models of NSCLC bone metastasis, RANKL inhibition led to decreased skeletal tumor progression and increased survival. By IHC, RANK expression has been reported to occur in approximately 60-70% of NSCLC cases profiled. Expression and function have been observed using human lung cancer cell line models. However, there is a lack of understanding with respect to the role RANK signaling plays in primary human lung tumor cells. To better understand RANK biology in lung cancer a novel platform was employed to measure RANK expression and pathway response to RANKL stimulation in freshly resected human lung tumors. RANK expression and function were investigated in viable, non-apoptotic disaggregated primary NSCLC samples by flow cytometry using previously described methodology. Cell surface RANK expression was evaluated using a monoclonal antibody (N2B10, Amgen). Evidence of receptor function was investigated by analysis of relevant intracellular signaling pathways using phospho-specific antibodies following ex vivo RANKL stimulation (2.5 pM - 5 µg/mL, 30 minutes). A cocktail of EGF, HGF and IGF1 was also employed as a positive control for functional pathway activation. Molecular profiling of somatic mutations is ongoing to further elucidate the molecular characteristics of tumors that have functional RANK signaling. Table 1 summarizes RANK expression and RANKL response profiles. This study demonstrates that RANK is expressed and functional in a subset of primary human lung tumors. Data presented here confirms RANK expression on tumor cells of NSCLC and suggests that RANK pathway utilization is restricted to the sub-set of tumors that express detectable RANK. Table 1SquamousAdenocarcinomaOther# Samples12217RANK Positive373NFκβ p65 Response1pAKT Response1pERK Response2p38 Responsep65 + pAKT Response1p38 + pERK Response1p65 + p38 + pAKT Response1% Responder (Total*)17%19%14%% Responder (RANK positive*)67%57%33%% Responder (EGF/ HGF/ IGF1)75%95%86%Other: large cell (1), carcinoid (1), adenosquamous (3), neuroendocrine (2)*Within Histology subtype Citation Format: John M. Rossi, Yang Pan, William C. Dougall, Daniel Branstetter, Allison Jacob, Jude Canon, Robert D. Loberg. Functional RANK expression is observed in disaggregated primary human lung tumors. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3320. doi:10.1158/1538-7445.AM2014-3320