Yang Shan-Shan, Yu De-Yang, Du Yu-Ting, Wang Le, Gu Lina, Zhang Yun-Yan, Xiao Min
Department of Gynecological Radiotherapy, Harbin Medical University Cancer Hospital, No. 150 HaPing Road, Nangang District, Harbin, 150081 China.
Department of Radiation Physics, Harbin Medical University Cancer Hospital, Harbin, 150081 China.
Cancer Cell Int. 2020 Jul 28;20:344. doi: 10.1186/s12935-020-01434-1. eCollection 2020.
Concurrent chemoradiotherapy is the common first-line treatment for patients with advanced cervical cancer. However, radioresistance remains a major clinical challenge, which results in recurrence and poor survival. Many studies have shown the potential of Delta-like Ligand 4 (DLL4) as a novel prognostic biomarker and therapeutic target in many solid tumors. Previously, we have found that high DLL4 expression in tumor cells may predict the pelvic lymph node metastasis and poor prognosis in patients with cervical cancer. In our present study, we further studied the effects of DLL4 on the biological behavior and radiosensitivity of cervical cancer cells.
The expression of DLL4 and epithelial-mesenchymal transition (EMT) phenotype markers in cervical cancer cell lines or tissues were detected using Western blotting, and the expression of DLL4 mRNA in cervical cancer cell lines or tissues was detected using Quantitative real-time PCR. The effect of DLL4 on cell proliferation, migration, and radiosensitivity was evaluated using the CCK8 assay, flow cytometry, Transwell assays for cell invasion and migration, and Immunofluorescence staining in vitro.
The expression of DLL4 in radiotherapy-resistant SiHa cells was significantly higher than that in radiotherapy-sensitive Me-180 cells. Furthermore, downregulation of DLL4 enhanced the radiosensitivity of SiHa and Caski cells via the inhibition of cell proliferation, promotion of radiation-induced apoptosis, and inhibition of the DNA damage repair. Moreover, downregulation of DLL4 inhibited the EMT and reduced the proliferation, invasion, and migration ability in SiHa and Caski cells. Consistent with the DLL4 expression in the cell lines, the expression of DLL4 in the tissues of the radioresistant group was also higher than that of the radiosensitive group.
Downregulation of DLL4 inhibited the progression and increased the radiosensitivity in cervical cancer cells by reversing EMT. These results indicated the promising prospect of DLL4 against the radioresistance and metastasis of cervical cancer and its potential as a predictive biomarker for radiosensitivity and prognosis in patients with cervical cancer patients receiving concurrent chemoradiotherapy (cCRT).
同步放化疗是晚期宫颈癌患者常见的一线治疗方法。然而，放射抗性仍然是一个主要的临床挑战，这会导致复发和生存率低下。许多研究表明，Delta样配体4（DLL4）在许多实体瘤中作为一种新型预后生物标志物和治疗靶点具有潜力。此前，我们发现肿瘤细胞中高表达的DLL4可能预示着宫颈癌患者盆腔淋巴结转移和预后不良。在本研究中，我们进一步研究了DLL4对宫颈癌细胞生物学行为和放射敏感性的影响。
采用蛋白质免疫印迹法检测宫颈癌细胞系或组织中DLL4和上皮-间质转化（EMT）表型标志物的表达，采用定量实时聚合酶链反应检测宫颈癌细胞系或组织中DLL4 mRNA的表达。使用CCK8法、流式细胞术、Transwell细胞侵袭和迁移试验以及体外免疫荧光染色评估DLL4对细胞增殖、迁移和放射敏感性的影响。
放疗抗性的SiHa细胞中DLL4的表达明显高于放疗敏感的Me-180细胞。此外，下调DLL4通过抑制细胞增殖、促进辐射诱导的凋亡以及抑制DNA损伤修复来增强SiHa和Caski细胞的放射敏感性。此外，下调DLL4抑制EMT，并降低SiHa和Caski细胞的增殖、侵袭和迁移能力。与细胞系中DLL4的表达一致，放射抗性组组织中DLL4的表达也高于放射敏感组。
下调DLL4通过逆转EMT抑制宫颈癌细胞的进展并提高其放射敏感性。这些结果表明DLL4在对抗宫颈癌放射抗性和转移方面具有广阔前景，并且作为接受同步放化疗（cCRT）的宫颈癌患者放射敏感性和预后的预测生物标志物具有潜力。
