Abstract 726: Involvement of proinflammatory chemokines in triple-negative breast cancer (TNBC)

Abstract

Abstract Objective: Triple-negative breast cancer (TNBC) accounts for 12-24% of total breast cancer, and contributes to the more aggressive, therapy-resistant and poorer outcomes. Our analysis based on The Cancer Genome Atlas (TCGA) indicated that basal-like BC subtype representing TNBC has enriched expression profiles for epidermal growth factor receptor 1 (EGFR) and transforming growth factor alpha (TGFá) compared to other subtypes. In addition, TNBC has a higher proinflammatory index compared to non-TNBC. Here we report that the proinflammatory chemokines such as CXCL1-3 and 8 are highly expressed in human TNBC cells and might be potentiated by TGFá-EGFR axis that contributes to cancer progression of TNBC. Methods: To gauge the role of TGFá-EGFR axis as a proinflammatory driver in TNBC cells, we first checked the expression profiles for EGFR family such as EGFR, HER2, ErbB3, and ErbB4 between TNBC (MCF10A, MB468, MB231, and BT549) and non-TNBC cells (MCF7, T47D). In addition, the expression levels of downstream signaling for EGFR (Akt/Erk) were measured by western blot. To dissect the role of TGFá-EGFR axis in enhancing proinflammatory index in TNBC cells, we utilized a more comprehensive study of the chemokines and chemokine receptors using human chemokine PCR array. Finally, to further confirm the role of TGFá-EGFR axis in inflammatory burden and cancer progression in TNBC, we used EGFR inhibitor and its downstream targets. Results: TNBC cells expressed more proinflammatory chemokines such as CXCL1-3 and 8 compared to non-TNBC cells. TNBC cells (MB468, MB231, and BT549) showed higher expression of EGFR which led to higher Akt activation as compared to non-TNBC cells. However, Erk is only activated in MB231. To dissect the involvement of Akt, expression of Akt isoforms in TNBC cells was accessed and Akt1 is the predominant isoform expressed in TNBC cells. To further assess the involvement of Akt1 in proinflammatory burden in TNBC cells, we used a commercial siRNA of Akt1 to knockdown Akt1. Knockdown of Akt1 significantly reduced the CXCL2 promoter activity. In addition, afatinib (an EGFR inhibitor) and MK2206 (an Akt inhibitor) significantly reduced the CXCL2 promoter activity. Conclusion: Thus, higher expression of proinflammatory chemokines CXCL1-3, and 8, via TGFá-EGFR axis-activated Akt, contributes to the inflammatory burden, probably promoting cancer progression, thereby followed by the overall high mortality in TNBC compared to non-TNBC. Citation Format: Rosa Mistica C. Ignacio, Carla Gibbs, Eun-Sook Lee, Deok-Soo Son. Involvement of proinflammatory chemokines in triple-negative breast cancer (TNBC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 726.