Phospholipase D1 promotes cervical cancer progression by activating the RAS pathway

This study aimed to further investigate the effect of PLD1 on the biological characteristics of human cervical cancer (CC) cell line, CASKI and the potential related molecular mechanism. CRISPR/Cas9 genome editing technology was used to knock out the PLD1 gene in CASKI cells. Cell function assays were performed to evaluate the effect of PLD1 on the biological function of CASKI cells in vivo and in vitro. A PLD1-overexpression rescue experiment in these knockout cells was performed to further confirm its function. Two PLD1-knockout CASKI cell lines (named PC-11 and PC-40, which carried the ins1/del4 mutation and del1/del2/ins1 mutation, respectively), were constructed by CRISPR/Cas9. PLD1 was overexpressed in these knockout cells (named PC11-PLD1 and PC40-PLD1 cells), which rescued the expression of PLD1 by approximately 71.33% and 74.54%, respectively. In vivo, the cell function assay results revealed that compared with wild-type (WT)-CASKI cells, the ability of PC-11 and PC-40 cells to proliferate, invade and migrate was significantly inhibited. The expression of H-Ras and phosphorylation of Erk1/2 (p-Erk1/2) was decreased in PC-11 and PC-40 cells compared with WT-CASKI cells. PC-11 and PC-40 cells could sensitize CASKI cells to cisplatin. More importantly, the proliferation, migration and invasion of PC11-PLD1 and PC40-PLD1 cells with PLD1 overexpression were significantly improved compared with those of the two types of PLD1 knockout cells. The sensitivity to cisplatin was decreased in PC11-PLD1 and PC40-PLD1 cells compared with PC-11 and PC-40 cells. In vivo, in the PC-11 and PC-40 tumour groups, tumour growth was significantly inhibited and tumour weight (0.95 ± 0.27 g and 0.66 ± 0.43 g vs. 1.59 ± 0.67 g, p = 0.0313 and 0.0108) and volume (1069.41 ± 393.84 and 1077.72 mm³  ± 815.07 vs. 2142.94 ± 577.37 mm³ , p = 0.0153 and 0.0128) were significantly reduced compared to those in the WT-CASKI group. Tumour differentiation of the PC-11 and PC40 cells was significantly better than that of the WT-CASKI cells. The immunohistochemistry results confirmed that the expression of H-Ras and p-Erk1/2 was decreased in PC-11 and PC-40 tumour tissues compared with WT-CASKI tumour tissues. PLD1 promotes CC progression by activating the RAS pathway. Inhibition of PLD1 may serve as an attractive therapeutic modality for CC.