MiR-223 promotes oral squamous cell carcinoma proliferation and migration by regulating FBXW7

Abstract

Abnormally expressed microRNAs (miRNAs) contribute widely to human cancer, including oral squamous cell carcinoma (OSCC), by regulating their downstream targets. MiR-223 has been proved to be up-regulated in both gastric cancer and ovarian cancer. However, the effect of miR-223 on OSCC is still unclear. Here, we showed that miR-223 was over-expressed in OSCC tissues using qRT-PCR. Next, we investigated the biological mechanism of miR-223 in OSCC. The results demonstrated that miR-223 facilitated the cell proliferation and migration of OSCC using MTT assay and Transwell assay. Furthermore, we stated that the FBXW7 expression was decreased in OSCC and re-expression of FBXW7 inhibited the proliferation and migration of OSCC. In addition, FBXW7 mimic inversed the promotion effect of miR-223 in regulating of OSCC cells. In short, miR-223 promoted OSCC cell proliferation and migration by downregulating FBXW7, which provided a novel therapeutic strategy for OSCC.

Keywords: FBXW7; MiR-223; OSCC; migration; proliferation.

Figure 1.

Increased miR-223 expression and decreased FBXW7 expression in OSCC cell lines and tissues. (A and B) Detection of miR-223 expression in OSCC cell lines and tissue samples by qRT-PCR. (C and D) Detection of FBXW7 mRNA expression in OSCC cell lines and tissue samples by qRT-PCR. (E) The relationship between FBXW7 expression and survival. (F) Regression analysis of negatively correlation of FBXW7 and miR-223 expression in 50 OSCC samples (${}^{*}P<$ 0.05, ${}^{**}P<$ 0.01, ${}^{***}P<$ 0.001). The experiments were repeated in triplicate.

Figure 2.

The promotion of miR-223 in the proliferation and apoptosis of OSCC cells. (A and B) Detection of the relative miR-223 mRNA expression in OECM1 and SCC15 cell lines after transfected with control mimic/inhibitor or miR-223 mimic/inhibitor (${}^{*}P<$ 0.05, ${}^{**}P<$ 0.01). (C and D) Detection of cell viability by MTT assay after the OECM1 and SCC15 cells lines transfected for 0, 24, 48, 72, 96 h with control mimic/inhibitor or miR-223 mimic/inhibitor (${}^{\mathrm{\#}}P<$ 0.05, ${}^{*}P<$ 0.05). (E and F) Detection of the relative PCNA mRNA level after the OECM1 and SCC15 cell lines transfected with control mimic/inhibitor or miR-223 mimic/inhibitor by qRT-PCR. (G) Detection of Caspase-8 protein level after the OECM1 and SCC15 cell lines transfected with control mimic/inhibitor or miR-223 mimic/inhibitor by western blot (${}^{*}P<$ 0.05, ${}^{**}P<$ 0.01). The experiments were repeated three times.

Figure 3.

The promotion of miR-223 in the migration of OSCC cells. (A and B) Detection of relative cell migration in OECM1 and SCC15 cells lines after transfected with control mimic/control mimic, miR-223 mimic/inhibitor by transwell assay (${}^{*}P<$ 0.05, ${}^{**}P<$ 0.01). These experiments were repeated in triplicate.

Figure 4.

FBXW7 as a target gene of miR-223 in regulating of OSCC cells. (A) The predicted sites of miR-223 in the 3’UTR of FBXW7. Between the 3’-UTR of FBXW7 and the complementary sites for the seed regions in miR-223 generated mutation. (B) Detection of the luciferase activity in OECM1 cells after transfected with miR-223 mimic/inhibitor (${}^{**}P<$ 0.01). (C and D) Detection of FBXW7 mRNA level and protein level in OECM1 cells after transfected with control mimic/inhibitor or miR-223 mimic/inhibitor by qRT-PCR (${}^{*}P<$ 0.05). These experiments were repeated three times.

Figure 5.

FBXW7 reversed miR-223-mediated OSCC cells proliferation and migration. (A) Detection of the relative FBXW7 mRNA expression in OECM1 cells after overexpression of FBXW7 for 48 h (${}^{*}P<$ 0.05, ${}^{**}P<$ 0.01). (B and C) MTT assays was performed to detect the cells viabilities in OECM1 and SCC15 cell lines after re-expression of FBXW7 for 0, 24, 48, 72, 96 h (${}^{*}P<$ 0.05). (D and E) Transwell assay detected the cell migration percents after overexpression of FBXW7 (${}^{*}P<$ 0.05). (F and G) Detection of the cell viability in OCEM1 and SCC15 cell lines by MTT assay after transfected with miR-223 mimic or both miR-223 mimic and FBXW7 vector (${}^{*}P<$ 0.05, ${}^{\mathrm{\#}}P<$ 0.05). (H and I) Transwell migration assay detected the relative cell migration percent in OCEM1 and SCC15 cell lines after transfected with miR-223 or both miR-223 mimic and FBXW7 vector (${}^{**}P<$ 0.01). These experiments were repeated three times.