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Cancer Cell Int. 2019 Feb 18;19:36. doi: 10.1186/s12935-019-0752-y. eCollection 2019.

Raltitrexed increases radiation sensitivity of esophageal squamous carcinoma cells.

Ding WX#1,2, Liu S#1, Ma JX#3, Pu J#4, Wang HJ1,5, Zhang S1, Sun XC1.

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1Department of Radiation Oncology, The First Affiliated Hospital of Nanjing Medical University, 300 Guanzhou Road, Nanjing, 210029 Jiangsu China.
2Department of Radiation Oncology, The Sixth Affiliated Hospital of Yangzhou University, Taixing Peoples' Hospital, Taizhou, Jiangsu China.
3Department of Radiation Oncology, Lianyungang Oriental Hospital, Lianyungang, Jiangsu China.
Department of Radiation Oncology, Lianshui Peoples' Hospital, Huaian, Jiangsu China.
5Department of Radiation Oncology, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Contributed equally



Radiation therapy remains an important therapeutic modality, especially for those patients who are not candidates for radical resection. Many strategies have been developed to increase the radiosensitivity of esophageal cancer, with some success.


This study was conducted to determine whether raltitrexed can enhance radiosensitivity of esophageal squamous cell carcinoma (ESCC). ESCC cell lines 24 h were incubated with raltitrexed or DMSO with or without subsequent irradiation. Cell Counting Kit assay-8 assay and clonogenic survival assay were used to measure the cell proliferation and radiosensitization, respectively. Flow cytometry was utilized to examine cell apoptosis and cell cycle distribution in different groups. Immunofluorescence analysis was performed to detect deoxyribonucleic acid (DNA) double-strand breaks. In addition, the expression levels of proteins that are involved in radiation induced signal transduction including Bax, Cyclin B1, Cdc2/pCdc2, and Cdc25C/pCdc25C were examined by western blot analysis.


The results indicated that raltitrexed enhanced radiosensitivity of ESCC cells with increased DNA double-strand breaks, the G2/M arrest, and the apoptosis of ESCC cells induced by radiation. The sensitization enhancement ratio of 1.23-2.10 was detected for ESCC cells with raltitrexed treatment in TE-13 cell line. In vitro, raltitrexed also increased the therapeutic effect of radiation in nude mice.


Raltitrexed increases the radiosensitivity of ESCC. This antimetabolite drug is promising for future clinical trials with concurrent radiation in esophageal cancer.


Cell apoptosis; Cell cycle arrest; Esophageal cancer; Radiosensitization; Raltitrexed

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