Fig. 6: SYCP2 promotes TC-HR independently of BRCA1.

A Plot of correlation between SYCP2 expression and IC50 of Olaparib, Cisplatin, and CPT11 in groups of BRCA WT vs. mutant cells (left), high BRCA1 vs. low BRCA1 (right). B siBRCA1 or siCtrl pretreated U2OSTRE cells transfected with GFP-SYCP2 and TA-KR were light-activated and recovered for 30 min. The frequency of foci-positive cells was quantified (n = 3 experiments, Mean +/− SEM). Fold increase of SYCP2 at TA-KR sites was quantified (n = 10 cells, Mean +/− SEM). C Comparison of SYCP2 RNA expression from CCLE database in BRCA1/2 mutant or proficient breast cancer cell lines (n = 6 samples, n = 65 samples, n = 15 samples, n = 59 samples). The analysis was normalized to Fragments Per Kilobase Million (FPKM). D IRIF of RAD51 1 hr after 2 Gy IR with or without siSYCP2 were quantified in HCC1954 and HCC1937 cells (n = 200 cells, Mean +/− SEM). Mean quantity of IRIF foci per cell is shown. WB of SYCP2, BRCA2, BRCA1 and RAD51 in HCC1937 and HCC1954 in siCtrl or siSYCP2 treated cells was shown. E IRIF of RAD51 1 hr after 2 Gy IR in HCC1954 and HCC1937 cells with empty vector or SYCP2 OE were quantified (n = 200 cells, Mean +/− SEM). Mean quantity of IRIF foci per cell is shown. F Cell survival rate of HeLa cells with siCtrl, siBRCA1, siSYCP2, or siBRCA1+siSYCP2 via colony-forming assay with the treatment of CPT11 at indicated dose (n = 3 experiments, Mean +/− SEM). (p = 0.0026, p = 0.0383, p = 0.0011) Statistical analysis was done with the unpaired two-tailed Student-t-test, ****p < 0.0001. Scale Bar = 10 μm. Source data are provided as a Source Data file.