Unlocking the Power of CXCR2 Inhibition to Overcome Gemcitabine Resistance in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related mortality, characterized by intrinsic resistance to conventional therapies and limited effective treatment options. In this study, we investigated the role of the CXCR2 axis in PDAC therapy resistance. CXCR2, a chemokine receptor, is actively involved in inflammation, tumor angiogenesis, and metastasis. Our working hypothesis is that CXCR2 contributes to PDAC chemotherapy resistance. To test this, we generated gemcitabine-resistant (GemR) lines using T3M4 and CD18/HPAF (CD18) cell lines. Baseline expression of CXCL1, CXCL5, and CXCL8 ligands were higher in GemR cells compared to parental cells. Upon gemcitabine treatment, parental cells exhibited a greater increase in CXCL1 and CXCL8 expression than GemR cells. Further analysis in T3M4 cells revealed a dose- and time-dependent increase in CXCL1 and CXCL8 expression following gemcitabine exposure. Next, we assessed whether targeting CXCR2 could enhance the therapeutic response. We treated parental and GemR cell lines with gemcitabine in combination with the CXCR2 antagonist SCH 479833 (SCH 47). Notably, lower concentrations of gemcitabine combined with SCH 47 were more effective than higher concentrations of gemcitabine alone in GemR cell lines. In both parental and GemR xenograft models, combination therapy with Navarixin (a CXCR2 antagonist) and gemcitabine demonstrated superior antitumor and antimetastatic activity compared to either treatment alone. In conclusion, these findings highlight the critical role of the CXCR2 axis in PDAC therapy resistance. Targeting CXCR2 enhances gemcitabine efficacy, offering a potential therapeutic strategy to overcome resistance in PDAC.