DUSP4 gene was overexpressed in the tissues and cell lines of CCRCC
Firstly, the GEPIA of TCGA database showed that the mRNA level of DUSP4 in CCRCC cancer tissues was significantly higher than that of paracancerous tissues (Fig. 1A). As shown in Fig. 1B, DUSP4 was significantly overexpressed in CCRCC tissue samples compared with paracancerous tissues. The correlation analyses related to clinical data showed that the increased DUSP4 levels was positively correlated with the growth, aggressiveness and metastasis of CCRCC cancer tissues (Table 1). Besides, 20 CCRCC samples with metastatic characteristic showed higher DUSP4 levels than 26 non-metastatic CCRCC samples (Fig. 1C). Moreover, compared with 21 CCRCC samples with a diameter less than 3 cm, 25 CCRCC samples with a diameter greater than 3 cm had higher DUSP4 expression (Fig. 1D). The detection of DUSP4 mRNA levels in normal renal tubular epithelial cell line HK-2 and CCRCC cell lines OS-RC-2, 786-O and Caki-1 showed that DUSP4 was significantly overexpressed in CCRCC cell lines (Fig. 1E).
DUSP4 overexpression promoted the proliferation and migration of CCRCC cells while DUSP4 silencing showed the opposite effect
To investigate the roles of DUSP4 in CCRCC, we overexpressed or silenced DUSP4 by transducing lentiviruses encoding DUSP4 (LV-DUSP4) or siRNAs against DUSP4 (si-DUSP4) into OS-RC-2 and 786-O cells (Fig. 2.A,E). CCK-8 assays displayed that DUSP4 overexpression promoted the proliferative levels of OS-RC-2 and 786-O cells (Fig. 2.B,F). In addition, Transwell assays showed that DUSP4 overexpression increased the number of migratory cells (Fig. 2.C,D,G,H). By contrast, DUSP4 knockdown showed the opposite effects in the proliferative and migratory abilities of OS-RC-2 and 786-O cells (Fig. 2.B-D, F-H).
DUSP4 overexpression promoted the tumorigenicity of CCRCC cells in vivo while DUSP4 silencing showed the opposite effect
To investigate the roles of DUSP4 in CCRCC in vivo, we injected DUSP4-overexpressed or DUSP4-silenced 786-O cells subcutaneously into nude mice. The import efficiency of DUSP4-overexpressed or DUSP4-silenced 786-O cells in xenograft tumors in vivo was verified by the results in Fig. 3A. As shown in Fig. 3.B-D, DUSP4 overexpression significantly enhanced the sizes, growth curve and weights of CCRCC xenograft tumors, while DUSP4 knockdown showed the opposite results, which supports the promotional effect of DUSP4 gene on CCRCC tumorigenicity.