Targeted Regulation of Mitosis through Eg5 Protein Enhances Radiosensitivity of Renal Cell Carcinoma

Renal cell carcinoma (RCC) is a radiation-resistant tumor. Eg5, a spindle motor protein, plays a crucial role in centrosome separation and bipolar spindle formation during mitosis. We explored whether Eg5 is an important therapeutic target for treating RCC.

We selected radiation-resistant 786-O renal carcinoma cells and divided them into four groups: Control, 10 Gy irradiation, Eg5 inhibitor, and 10 Gy + Eg5 inhibitor. The proliferative ability of the tumor cells was assessed using the cell counting kit-8 assay; A transwell assay was employed to evaluate their invasive capacity. A clonogenic assay was performed to assess clonogenic survival. We divided the 786-O renal carcinoma cells into 10 Gy irradiation and 10 Gy + Eg5 inhibitor groups. Flow cytometry, cell cycle analysis, polymerase chain reaction (PCR), and western blotting were conducted to compare radiosensitivity between the two groups and to investigate potential underlying mechanisms.

The levels of cell proliferation, clonogenic survival, and migration in the 10 Gy + Eg5 inhibitor group (0.395 ± 0.007, 119.3 ± 7.513, 24.33 ± 2.333, respectively) were significantly lower than those in the control (0.772 ± 0.005, 294.3 ± 10.710, 83.00 ± 3.786, respectively) and 10 Gy groups (0.667 ± 0.006, 211.7 ± 9.528, 54.33 ± 2.728, respectively) (p < 0.05). Flow cytometry showed that the level of apoptosis in the 10 Gy + Eg5 inhibitor group (16.87 ± 2.476, 17.0%) was significantly higher than in the 10 Gy group (6.319 ± 0.380, 6.0%) (p < 0.05). Flow cytometry analysis further revealed that the proportion of cells in the G1 phase in the 10 Gy + Eg5 inhibitor group (10.037 ± 1.434) was lower than in the 10 Gy group (24.327 ± 2.252) (p < 0.05). PCR results showed that the messenger ribonucleic acid (mRNA) levels of H2AX, TP53BP1, XRCC1, and CDKN1A in the 10 Gy + Eg5 inhibitor group were significantly higher than those in the 10 Gy group (p < 0.05).

Eg5 inhibitors specifically bind to the Eg5 protein and disrupt mitosis, thereby improving the radiosensitivity of RCC by regulating the cell cycle. An Eg5 inhibitor combined with radiotherapy may represent an effective adjuvant therapy for RCC.