Abstract 3443: CXCR2 inhibition decreases invasion and metastasis of a <i>KRAS/p53</i>-mutant lung adenocarcinoma cell line <i>in vitro</i> and <i>in vivo</i>
Authors: Erminia Massarelli, Baruch Erez, Sangeeta Goswami, Jonathan M. Kurie
Journal: Cancer Research (2012)

Abstract Background: The tumor microenvironment of human non-small cell lung cancer (NSCLC) is composed of a variety of cell types, which are functionally and phenotypically heterogeneous and provide multiple complex regulatory signals. CXCR2 in NSCLC has been mainly studied in stromal cells and is known to increase tumor inflammation and angiogenesis. We have previously reported that alveolar epithelial cells transformed by oncogenic KRAS have high expression of CXCR2 (IL8R) ligands, which recruit inflammatory and endothelial cells and promote the progression of premalignant alveolar lesions to lung adenocarcinoma (ADC). In addition, we have shown that murine cancer associated fibroblasts (CAF) abundantly secrete CXCR2 ligands and that these ligands promote lung adenocarcinoma inflammation, angiogenesis, and growth. The purpose of our study was to investigate the role of CXCR2 expression in lung ADC tumoral cells in vitro and in vivo in promoting tumoral cell invasion and metastasis. Material and Methods: We created stable shRNA knockdown clones derived from a murine KrasLA1/+p53R172HαG/+ cell line (344SQ) which develops aggressive and metastatic lung ADC once injected in syngeneic mice. Invasion was assessed in vitro by co-cultures of two CXCR2-shRNA clones (clone-1 and clone-3) and CAF in 24-well Transwell invasion plates, compared to scrambled control (ctrl). In order to block tumoral cell proliferation, we added mitomycin C to the serum-free media of the tumoral cells. To assess the in vivo tumoral invasion and metastatic potential of the shRNA clones, 2x104 cells of the two different shRNA clones and of the ctrl were injected into the left lung of syngeneic mice (N=10 mice each group). Mice were euthanized at first signs of poor physical conditions due to tumor burden. Wilcoxon rank sum test was used for statistical calculations. Results: The two CXCR2-shRNA clones showed a significantly lower invasion potential in vitro when compared to ctrl (clone-1 vs. ctrl p=0.002; clone-3 vs. ctrl p=0.04). Mice were euthanized after 21 days from injection because 2 out of 10 showed poor physical conditions in the control group. At necropsy, mice bearing CXCR2-shRNA lung ADCs had significantly smaller primary tumors (clone-1 vs. ctrl p=0.03; clone-3 vs. ctrl p=0.008), decreased number of lung tumor nodules in the same lung of primary injection (clone-1 vs. ctrl p=0.02), decreased number of mediastinal lymph node metastases (clone-1 vs. ctrl p=0.004; clone-3 vs. ctrl p=0.003) and decreased number of distant metastases (clone-1 vs. ctrl p=0.004; clone-3 vs. ctrl p=0.02), when compared to ctrl. Conclusion: CXCR2 inhibition decreases invasion and metastases in vitro and in vivo in a murine model of KRAS/p53-mutant lung ADC and may be an important target in KRAS-mutated human lung ADC. (Supported by A.S.C.O Conquer Cancer Foundation Young Investigator Award to E. Massarelli). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3443. doi:1538-7445.AM2012-3443