Abstract: [Objective] To verify the role of β-defensin-1 in inhibiting the growth of colon cancer via circular RNA HAS-CIRCpedia-5280 by subcutaneous tumorigenesis experiments in nude mice. [Methods] Lentiviral transduction technology was performed to transduce human colon carcinoma HCT-116 cells with the overexpression lentivirus carrying HAS-CIRCpedia-5280 and empty-vector control lentivirus, respectively. After polybrene-assisted infection and puromycin screening for 2 weeks, HAS-CIRCpedia-5280 overexpression stably transduced HCT-116 cell line （HAS-CIRCpedia-5280 cells） and empty vector control stably transduced HCT-116 cell line （NC cells） were constructed. Thirty BALB/c-nu nude mice were divided into 6 groups[oe-NC group, subcutaneously injected with NC cells; oe-circRNA group, subcutaneously injected with HAS-CIRCpedia-5280 cells; oe-NC+PBS group, subcutaneously injected with NC cells and intraperitoneally injected with PBS; oe-circRNA+PBS group, subcutaneously injected with HAS-CIRCpedia-5280 cells and intraperitoneally injected with PBS; oe-NC+hBD-1 （human β-defensin-1） group, subcutaneously injected with NC cells and intraperitoneally injected with hBD-1; oe-circRNA+hBD-1 group, subcutaneously injected with HAS-CIRCpedia-5280 cells and intraperitoneally injected with hBD-1], with 5 mice in each group. The BALB/c-nu nude mice subcutaneous xenograft tumor model was established by subcutaneous injection of the above two kinds of stably transduced cells. The oe-NC+hBD-1 group and the oe-circRNA+hBD-1 group, the oe-NC+PBS group and the oe-circRNA+PBS group were intraperitoneally injected with 0.1 mg/（kg·BW） hBD-1 or an equal volume of PBS, respectively, for intervention, twice a week （Monday and Thursday）, and tumor volume was recorded every 7 days. All injections were completed within 4 weeks from the first administration. The nude mice were euthanized 72 h after the last administration, and the tumor tissues were dissected to measure tumor volume and weight. [Results] HAS-CIRCpedia-5280 overexpression （oe-circRNA） and empty vector control （oe-NC） stably transduced HCT-116 cell lines were constructed by lentivirus transduction. Fluorescence microscopy showed that most cells in the oe-circRNA group and oe-NC group exhibited clear green fluorescence, and the positive rate of cells was higher. The results of qRT-PCR showed that compared with the oe-NC control group, the expression level of HAS-CIRCpedia-5280 in the oe-circRNA group was extremely significantly up-regulated （P<0.01）. A subcutaneous xenograft tumor model of colon cancer in nude mice was constructed, and tumor growth was regularly monitored. The results showed that compared with the oe-NC group, the weight of transplanted tumor in the oe-circRNA group was extremely significantly increased （P<0.01）, and the volume was significantly increased （P<0.05）. qRT-PCR detection confirmed that the expression level of HAS-CIRCpedia-5280 in the oe-circRNA group was extremely significantly up-regulated compared with the oe-NC group （P<0.01）. An hBD-1 intraperitoneal intervention experiment was conducted on the colon cancer xenograft tumor model in nude mice. Compared with the oe-NC+PBS group, the weight of transplanted tumors in the oe-circRNA+PBS group was extremely significantly increased （P<0.01） and the volume was significantly enlarged （P<0.05）; the weight of transplanted tumors in the oe-NC+hBD-1 and oe-circRNA+hBD-1 groups was extremely significantly decreased （P<0.01） and the volume was significantly reduced （P<0.05）. qRT-PCR detection showed that, compared with the oe-NC+PBS group, the expression level of HAS-CIRCpedia-5280 in the oe-NC+hBD-1 group was significantly down-regulated （P<0.05）; compared with the oe-circRNA+PBS group, the expression of HAS-CIRCpedia-5280 in the oe-circRNA+hBD-1 group was significantly down-regulated （P<0.05）. [Conclusion] The experimental results indicate that overexpression of HAS-CIRCpedia-5280 promotes the growth of colon cancer xenograft tumors. Further studies found that hBD-1 treatment can effectively down-regulate the expression of HAS-CIRCpedia-5280 and inhibit the growth of xenograft tumors. It is therefore speculated that hBD-1 inhibits the progression of colon cancer through HAS-CIRCpedia-5280.

Key words: beta-defensin-1, human beta-defensin-1, HAS-CIRCpedia-5280, colon cancer