Additional file 1: Figure S1. Bioinformatics analysis of NCAPG2 expression in PCa based on TCGA and GTEx datasets. a Based on TCGA database, NCAPG2 showed a higher level in PCa tissues compared with normal tissues. b NCAPG2 expression was higher in PCa tissues than in paired paracancerous tissues from TCGA database. c Combined with TCGA and GTEx data, NCAPG2 exhibited a higher expression pattern in PCa tissues. d-g The expression of NCAPG2 in PCa patients with different tumor stages, different N stages, different grades of Gleason score and different levels of serum PSA. h NCAPG2 expression was higher in PCa patients with poor response after primary treatment. i NCAPG2 expression was higher in PCa patients with residual tumor after surgery. j PCa-specific death likelihood was greater for patients with higher expression of NCAPG2. k Patients with higher NCAPG2 expression in primary tumors had a significantly decreased PFI. PCa prostate cancer, TCGA The Cancer Genome Atlas, GTEx The Genotype-Tissue Expression, CR complete response, PR partial response, SD stable disease, PD progressive disease, R0 no residual tumor, R1 microscopic residual tumor, R2 macroscopic residual tumor, DSS disease-specific survival, PFI progression-free interval, ROC receiver operating characteristic curve. P values were defined by the Wilcoxon test. * means P < 0.05, ** means P < 0.01, *** means P < 0.001, ns means P > 0.05, and P < 0.05 is defined as statistically significant. Figure S2. NCAPG2 had a good diagnostic and prognostic ability for PCa. a, b NCAPG2 yielded good ROC diagnostics in PCa from TCGA and GTEx databases. c-f The tdROC indicated that the level of NCAPG2 could effectively predict the 3-year, 6-year, 8-year and 10-year PFI survival of PCa patients, respectively. g-i PCa patients with high expression of NCAPG2 showed a poor BCR survival based on the DKFZ2018 database, GSE70769 database, and MSKCC2010 database. PCa prostate cancer, TCGA The Cancer Genome Atlas, tdROC time-dependent receiver operating characteristic curve, PFI progression-free interval, BCR biochemical recurrence. P < 0.05 is defined as statistically significant. Figure S3. Representative images of HE staining of PCa and para-carcinoma tissue sections. Figure S4. NCAPG2 overexpression promotes the proliferation, migration, invasion of PCa cells in vitro. a, b qPCR and WB analysis of NCAPG2 expression in LNCaP and DU145 cells after transfection of oe-NC or NCAPG2 plasmids. c In CCK-8 assay, both LNCaP and DU145 cells in oe-NCAPG2 group showed a faster proliferation status. d Colony formation assay showed that LNCaP and DU145 cells in oe-NCAPG2 group formed more colonies. e, f The migration rate and invasion ability of LNCaP and DU145 cells were enhanced with NCAPG2 overexpression, as shown by wound healing assay and transwell assay. PCa prostate cancer, WB western blot. P values were calculated by the Student’s t-test. * means P < 0.05, ** means P < 0.01, *** means P < 0.001, ns means P > 0.05, and P < 0.05 is defined as statistically significant. Figure S5. Representative images of HE staining for subcutaneous tumors (a) and WB analysis of NCAPG2 and p21 protein expression in the subcutaneous tumors (b-e). HE hematoxylin and eosin, WB western blot. P values were calculated by the Student’s t-test. *** means P < 0.001, and P < 0.05 is defined as statistically significant. Figure S6. NCAPG2 upregulation promotes the growth of PCa in vivo. a Representative images of subcutaneous xenograft derived from the oe-NCAPG2 and oe-NC PCa cells. b, c Tumor volume and body weight in nude mice of oe-NCAPG2 and oe-NC group were measured every 5 days. d The size and weights of subcutaneous tumors in the oe-NCAPG2 group were significantly larger than the oe-NC group. e Representative images of HE staining for subcutaneous xenograft derived from the oe-NC and oe-NCAPG2 PCa cells. f-i WB assays for NCAPG2 and p21 protein expression and quantitative results. PCa prostate cancer, HE hematoxylin and eosin, WB western blot. P values were calculated by the Student’s t-test. * means P < 0.05, ** means P < 0.01, *** means P < 0.001, and P < 0.05 is defined as statistically significant. Figure S7. NCAPG2 contributes to PCa malignancy through the mediation of c-MYC. a Knockdown of NCAPG2 inhibited the colonies formation of PCa cells (LNCaP and DU145), but overexpression of c-MYC could reverse the inhibitory effect. b Knockdown of NCAPG2 inhibited the migration ability of PCa cells, while overexpression of c-MYC could reverse above effect. c Knockdown of NCAPG2 inhibited invasiveness of PCa cells, while overexpression of c-MYC could reverse this inhibition. d-f NCAPG2 overexpression enhanced the colonies formation, PCa cell migration and invasiveness, while downregulation of c-MYC could reverse above effects. g. IHC results of subcutaneous tumor indicated that NCAPG2 knockdown led to reduction in the level of c-MYC. PCa prostate cancer, IHC immunohistochemical staining. P values were defined by Student’s t-test. * means P < 0.05, ** means P < 0.01, *** means P < 0.001, and P < 0.05 is defined as statistically significant.

Additional File 1 of NCAPG2 Promotes Prostate Cancer Malignancy and Stemness Via STAT3/c-MYC Signaling