1. γ-H2AX as a potential indicator of radiosensitivity in colorectal cancer cells
- Author
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Keitaro Tanaka, Yosuke Inomata, Masashi Yamamoto, Kazuhisa Uchiyama, Nao Kawaguchi, Masaru Kawai, Satoshi Kawashima, Junji Okuda, Tomohito Tanaka, Ryo Tanaka, Yoshiro Imai, Kohei Taniguchi, Yoshihiro Inoue, Sang-Woong Lee, Kazumasa Komura, and Keitaro Tashiro
- Subjects
0301 basic medicine ,Oncology ,Cancer Research ,medicine.medical_specialty ,Colorectal cancer ,γ-H2A histone family member X ,colorectal cancer ,environment and public health ,Metastasis ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,medicine ,Radiosensitivity ,Predictive marker ,Oncogene ,business.industry ,Microsatellite instability ,Cancer ,Articles ,medicine.disease ,030104 developmental biology ,γ-H2AX ,radiosensitivity ,030220 oncology & carcinogenesis ,Cancer cell ,preoperative chemoradiotherapy ,biological phenomena, cell phenomena, and immunity ,business - Abstract
Preoperative radiotherapy improves local disease control and disease-free survival in patients with advanced rectal cancer; however, a reliable predictive biomarker for the effectiveness of irradiation has yet to be elucidated. Phosphorylation of H2A histone family member X (H2AX) to γ-H2AX is induced by DNA double-strand breaks and is associated with the development of colorectal cancer (CRC). The current study aimed to clarify the relationship between γ-H2AX expression and CRC radiosensitivity in vitro and in vivo. H2AX levels were analyzed in datasets obtained from cohort studies and γ-H2AX expression was investigated by performing immunohistochemistry and western blotting using clinical CRC samples from patients without any preoperative therapy. In addition, the CRC cell lines WiDr and DLD-1 were subjected to irradiation and/or small interfering RNA-H2AX, after which the protein levels of γ-H2AX were examined in samples obtained from patients undergoing preoperative chemoradiotherapy. To quantify the observable effect of treatment on cancer cells, outcomes were graded as follows: 1, mild; 2, moderate; and 3, marked, with defined signatures of cellular response. Datasets obtained from cohort studies demonstrated that H2AX mRNA levels were significantly upregulated and associated with distal metastasis and microsatellite instability in CRC tissues, in contrast to that of normal tissues. In addition, γ-H2AX was overexpressed in clinical samples. In vitro, following irradiation, γ-H2AX expression levels increased and cell viability decreased in a time-dependent manner. Combined irradiation and γ-H2AX knockdown reduced the viability of each cell line when compared with irradiation or γ-H2AX knockdown alone. Furthermore, among clinical CRC samples from patients undergoing preoperative chemoradiotherapy, levels of γ-H2AX in the grade 1 group were significantly higher than those in grade 2 or grade 3. In conclusion, γ-H2AX may serve as a novel predictive marker and target for preoperative radiotherapy effectiveness in patients with CRC.
- Published
- 2020