This study aimed to investigate the crucial mutant gene of Chinese patients with retinoblastoma (Rb) by whole-exome sequencing (WES), and explore the functional role of this genetic variant in the development of Rb using biological experiments.

Blood samples of 82 Rb patients with negative RB1 gene mutation (RB1-/-) in China were screened for rare variations via WES analysis. Moreover, the expression of protein encoded by selected rare variants was detected by Western blot. We further observed the effect of selected gene knockdown or overexpression on the proliferation, migration of Rb cells and xenograft tumor size in vitro and in vivo.

We identified a rare variation Y318H of PLK3 gene in RB1-/- patients by WES and SKAT analysis, and Y318H substitution was a pathogenic mutation. The PLK3 protein of Rb cell lines transfected with Y318H mutation plasmids was reduced compared to the control. PLK3 knockdown promoted the proliferation and migration potentials of Rb cells, while PLK3 overexpression inhibited the proliferation and migration potentials of Rb cells. Additionally, the transition of PLK3 expression regulated Rb growth of mouse subcutaneous xenograft model in vivo.

Our findings provide evidence that the rare variation Y318H of PLK3 gene is an significant pathogenic factor for Rb progression in Chinese patients. The mutation of Y318H can reduce PLK3 protein expression. PLK3 knockdown promoted the proliferation and migration of Rb cells, thereby resulting in the growth of Rb. The study suggests that PLK3 rare variation Y318H can be used as a new molecular marker for the early genetic screening of Rb, and may provide a novel target for diagnosis and treatment of the disease.