SPI1 mediates transcriptional activation of TPX2 and RNF2 to regulate the radiosensitivity of lung squamous cell carcinoma.

Radiotherapy acts by damaging DNA and hindering cancer cell proliferation. H2AX is phosphorylated to produce γH2AX that accumulates in a response to DNA double-strand breaks. Non-coding RNA can influence DNA damage response and enhance DNA repair, which show potential for cancer treatment. The study aimed to observe the influence of SPI1 on the radiosensitivity of lung squamous cell carcinoma (LUSC) and to investigate the mechanisms. SPI1, TPX2, and RNF2 were overexpressed in LUSC tissues and radioresistant cells comspared with adjacent tissues and parental cells, respectively. The binding between SPI1 and TPX2 or RNF2 promoter was investigated using ChIP-qPCR and dual-luciferase assays. SPI1 bound to TPX2 and RNF2 promoters and activated their transcription. SPI1 downregulation increased the radiosensitivity of LUSC cells, which was compromised by TPX2 or RNF2 overexpression. Meanwhile, SPI1 downregulation elevated the protein expression of γH2AX at the late stage of DNA damage response and suppressed DNA damage repair in LUSC cells, which were compromised by TPX2 or RNF2. These results indicate that SPI1 silencing potentiates radiosensitivity in LUSC cells by downregulating the transcription of TPX2 and RNF2, which provides a potential target for the radiotherapy in LUSC.