Abstract 1987: Lysophosphatidic acid's unknown role in the initiation and progression of gastric cancer through LPAR2 receptor and beta-catenin signaling pathway by altering the energy metabolism
Authors: Ara Hosne , Bhattarai Susmita , Sharma Sudha , Subedi Utsab , Bhuiyan MD.Shenuarin , Yu Xiuping , Miriyala Sumitra , Panchatcharam Manikandan 
Published: July 2021

Introduction: Lysophosphatidic acid (LPA), a multifunctional endogenous phospholipid, plays a vital role in cellular homeostasis and malignant behavior of the cancer cells through G-protein coupled receptors. Although dysregulated beta-catenin signaling pathway has been reported as a critical mediator of gastric cancer, LPA's role in beta-catenin mediated gastric cancer is unknown. Hence, our study aims to determine LPA's functional role and its downstream signaling mechanism in beta-catenin mediated gastric cancer.

Method: We used commercially available tissue lysates from the human normal and cancerous stomach to check the LPA level and the expression of LPA receptors by ELISA, western blotting, and Immunohistochemical analysis. To examine LPA's functional effect in gastric cancer, we performed ECIS proliferation, migration assay, scratch assay, and transwell invasion assay in LPA treated gastric cancer cells. Next, to elucidate LPA's molecular mechanism mediated gastric cancer progression, we performed Western blotting, and Real-time PCR of beta-catenin and its downstream target genes in LPA treated cells. To investigate the LPA-induced beta-catenin activity, Luciferase assay, Immunocytochemistry, and nuclear fractionation were done in LPA-treated cells. TCGA database analysis was carried out to check the mRNA level of beta-catenin and its downstream target genes and LPA receptors. Furthermore, superoxide production and Seahorse analysis were performed in the LPA treated cells to determine the oxidative stress and mitochondrial energy metabolism.

Result: LPA ELISA and Western blotting of LPA receptors in human gastric cancer tissues showed that the LPA level is significantly higher (P&lt;0.001), and LPAR2 is robustly increased (P&lt;0.001)in human gastric cancer tissue samples suggesting a possible role of LPA in gastric cancer. In cultured gastric cancer cell line, LPA treatment increased proliferation, migration, and invasion activity, whereas LPA receptor antagonist abrogated the LPA induced effect. Similarly, LPA treatment leads to activate the beta-catenin and increased the expression of the downstream target genes of the beta-catenin signaling pathway. LPA-induced activation of beta-catenin signaling pathway was abrogated with the addition of LPA receptor antagonist and knockdown of LPAR2. Besides, LPA treatment increased oxidative stress and increased glucose uptake and ATP production (P&lt;0.001) by both oxidative phosphorylation and glycolysis, whereas LPA antagonist abrogated this effect.

Conclusion: Together, all of our results suggested that LPA mediates gastric cancer initiation and progression through the beta-catenin signaling pathway via the LPAR2 receptor by altering energy metabolism. Our findings will provide a novel insight into gastric cancer treatment.

Citation Format: Hosne Ara, Susmita Bhattarai, Sudha Sharma, Utsab Subedi, MD.Shenuarin Bhuiyan, Xiuping Yu, Sumitra Miriyala, Manikandan Panchatcharam. Lysophosphatidic acid's unknown role in the initiation and progression of gastric cancer through LPAR2 receptor and beta-catenin signaling pathway by altering the energy metabolism [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1987.