Roles of lysophosphatidic acid (LPA) receptor-2 (LPA₂) in the regulation of cellular responses induced by X-ray irradiation and hydrogen peroxide in pancreatic cancer cells

Abstract

Purpose

Lysophosphatidic acid (LPA) receptor-mediated signaling regulates various biological functions in cancer cells. This study aimed to evaluate the roles of LPA receptor-2 (LPA₂) in cellular responses induced by X-ray irradiation in pancreatic cancer PANC-1 cells. Since X-ray irradiation generates reactive oxygen species (ROS), PANC-1 cells were treated with hydrogen peroxide (H₂O₂). H₂O₂ is a key member of ROS.

Methods

To investigate the cell survival rate to X-ray irradiation, PANC-1 cells were irradiated with X-rays (2.5–15 Gy). LPAR2 expression levels were measured by quantitative real-time RT-PCR analysis. The effects of LPA₂ on the cell survival and motility were evaluated using LPA₂ knockdown cells. To establish H₂O₂ treated cells, PANC-1 cells were cultured in 10% FBS-DMEM with H₂O₂ (30 µM) for 2 weeks. The cell motility and survival rate to cisplatin (CDDP) of H₂O₂ treated cells were examined.

Results

LPAR2 expression was significantly increased in PANC-1 cells irradiated with X-rays. PANC-1 cell motility was markedly decreased by X-ray irradiation. The reduced cell motility activity by X-ray irradiation was enhanced by LPA₂ knockdown. The cell survival to X-ray irradiation was elevated in PANC-1 cells treated with GRI-977143 (LPA₂ agonist) and suppressed by LPA₂ knockdown. On the other hand, LPAR2 expression was markedly higher in H₂O₂ treated cells than in H₂O₂ untreated cells. H₂O₂ treated cells showed the high cell survival to CDDP in comparison with H₂O₂ untreated cells. GRI-977143 increased the cell survival to CDDP of H₂O₂ treated cells, while LPA₂ knockdown suppressed.

Conclusions

The present results suggest that the activation of LPA₂-mediated signaling plays an important role in the modulation of cellular functions induced by X-ray irradiation and H₂O₂ in PANC-1 cells.

Keywords:

• LPA signaling
• LPA₂
• X-ray irradiation
• hydrogen peroxide
• pancreatic cancer cells

Author contributions

A.O. performed experiments and analyzed data. M.T., R.K. and M.T. assisted in cell culture experiments. H.I. performed X-ray irradiation. T.T. designed the present study and wrote the manuscript. All authors approved the final version of the manuscript being submitted.

Ethics statement

This article does not contain any studies with human participants or animals performed by any of the authors.

Disclosure statement

The authors declare that they have no conflict of interest.

Data availability statement

All data generated or analyzed during the present study are included in this published article.

Additional information

Funding

This study was supported by JSPS KAKENHI under Grant Numbers JP18K07249, 21K07109 to T.T.

Notes on contributors

Aya Okuda

Aya Okuda, PhD, Research Scholar, Division of Molecular Oncology, Department of Life Science, Faculty of Science and Engineering, Kindai University, Japan.

Miwa Takai

Miwa Takai, Master student, Division of Molecular Oncology, Department of Life Science, Faculty of Science and Engineering, Kindai University, Japan.

Rio Kurisu

Rio Kurisu, Master student, Division of Molecular Oncology, Department of Life Science, Faculty of Science and Engineering, Kindai University, Japan.

Miyu Takamoto

Miyu Takamoto, Master student, Division of Molecular Oncology, Department of Life Science, Faculty of Science and Engineering, Kindai University, Japan

Hiroko Ikeda

Hiroko Ikeda, PhD, Assistant Professor, Division of Molecular Oncology, Department of Life Science, Faculty of Science and Engineering, Kindai University, Japan.

Toshifumi Tsujiuchi

Toshifumi Tsujiuchi, DDS, PhD, Professor, Division of Molecular Oncology, Department of Life Science, Faculty of Science and Engineering, Kindai University, Japan.