Anticancer drug-treated fibroblasts modulate colon cancer cell behavior through lysophosphatidic acid (LPA) receptor-mediated signaling.

Lysophosphatidic acid (LPA) receptor-mediated signaling contributes to the pathogenesis of cancer. The tumor microenvironment (TME), composed of cancer cells and surrounding stromal cells, plays a key role in promoting malignant traits, including resistance to anticancer drugs. In this study, we investigated the roles of LPA receptor-1 (LPA1) and LPA2 in colon cancer DLD-1 cell functions modulated by 3T3 fibroblasts chronically exposed to chemotherapy. 3T3 cells were treated long-term with fluorouracil (5-FU), irinotecan (CPT-11), or cisplatin (CDDP) to generate 3T3-5FU, 3T3-CPT11, and 3T3-CDDP cells, respectively. Co-culture with anticancer drug-treated 3T3 cells altered LPA receptor expression in DLD-1 cells, characterized by reduced LPAR1 and elevated LPAR2 levels, compared with co-culture with untreated fibroblasts (n = 3 independent experiments). Under these conditions, LPA stimulation enhanced DLD-1 cell proliferation and motility. Pharmacological modulation of LPA signaling further supported receptor-specific effects: the LPA1 antagonist AM966 and the LPA2 agonist GRI-977143 promoted DLD-1 cell growth, while AM966 suppressed and GRI-977143 enhanced cell motility in co-culture with drug-treated fibroblasts. These findings suggest that chemotherapy-conditioned fibroblasts reshape LPA receptor-dependent signaling in colon cancer cells, suggesting potential therapeutic relevance of distinct roles for LPA1 and LPA2 within the drug-modified TME.