Abstract 2117: The novel and comprehensive screening of genes resistant to an anticancer drug and radiation in esophageal squamous cell carcinoma
Authors: Kawakubo Hirofumi , Fukuda Kazumasa , Kigasawa Yu , Takesue Tomoko , Tsutsui Mai , Takahashi Tsunehiro , Nakamura Rieko , Wada Norihito , Takeuchi Hiroya , Kitagawa Yuko 
Published: July 2016

Background: Esophageal cancer has a poor prognosis due to early metastasis and direct invasion. Multimodal therapies including surgery, chemotherapy, and radiotherapy are necessary for advanced esophageal cancer. Although chemo or radiosensitivity is closely related to prognosis, it is currently impossible to predict the therapeutic effect of therapies. Patients with resistance to chemo or radiotherapy cannot derive benefit from the therapy but suffer side effects. Therefore, detecting resistant genes and mechanisms is essential for tailoring treatment to improve the prognosis.

Drug and radiation resistance may be mediated by genetic changes in the tumor; therefore, the identification of gene mutations may lead to better therapeutic outcomes. We used a novel method involving transposons to screen and identify drug-resistant genes and radio-resistant genes.

Methods: A modified piggyBac transposon was designed as an insertion mutagen, and a cytomegalovirus (CMV) promoter sequence was added to induce strong transcription. After establishing a transposon-tagged cell library, we treated cell lines derived from esophageal squamous cell carcinomas (ESCC) [Tohoku Esophagus (TE)] with cisplatin (CDDP) or radiation. We performed splinkerette PCR and TOPO cloning on the resistant colonies. Bacterial colonies were sequenced, and Next-Generation sequencing was used to identify the over-expressed/down-regulated sequences as candidate genes for CDDP resistance or radiation resistance,

Results: We established 4 cell lines of transposon-tagged cells, TE 4, 5, 9, and 15. We treated the 2 relatively viable cell lines, TE4 and TE15, with CDDP or irradiation. We identified 37 candidate genes from 8 resistant colonies for CDDP. Eight genes were over-expressed whilst 29 were down-regulated. Eleven genes were detected as candidate radioresistant genes.

Conclusions: The new gene screening technique was useful for detecting candidate of drug-resistant genes and radio-resistant genes in esophageal squamous cell carcinoma. We identified 37 candidate genes responsible for CDDP resistance in the two cell lines derived from ESCC cells. Eleven genes were detected as candidate radioresistant genes in the two cell lines derived from ESCC cells.The method is inexpensive, relatively simple, and capable of introducing activating and de-activating mutations in the genome, allowing for drug-resistant genes and radio-resistant genes to be identified.

Citation Format: Hirofumi Kawakubo, Kazumasa Fukuda, Yu Kigasawa, Tomoko Takesue, Mai Tsutsui, Tsunehiro Takahashi, Rieko Nakamura, Norihito Wada, Hiroya Takeuchi, Yuko Kitagawa. The novel and comprehensive screening of genes resistant to an anticancer drug and radiation in esophageal squamous cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2117.