ABSTRACT
Colorectal cancer (CRC) is one of the major threats to human health worldwide. In the treatment of CRC, chemoresistance affects the efficacy of platinum-based therapies. Oxaliplatin is one of the most commonly used first-line medications for the treatment of CRC; however, chemoresistance is common among patients receiving oxaliplatin treatment, which significantly decreases its therapeutic efficacy. The present study focused on the roles of microRNA (miR)-96 in the oxaliplatin resistance of CRC cells and the underlying mechanisms. First, the expression of miR-96 was compared between CRC and adjacent tissues. Furthermore, target genes of miR-96 were predicted, and a dual-luciferase reporter assay was employed to confirm whether the candidate tropomyosin 1 (TPM1) is a direct target of miR-96. In addition, CRC cells were transfected with miR-96 inhibitor, miR-negative control, small interfering RNA (siRNA) targeting TPM1 or siRNA NC, and then treated with oxaliplatin. CCK-8 assay and flow cytometry were performed to examine the proliferation and apoptosis of the CRC cell line SW480. Next, reverse transcription-quantitative PCR and western blot analysis were performed to determine the mRNA and/or protein levels of miR-96, Bcl-2, BAX and TPM1. The results indicated that miR-96 was upregulated in CRC compared with normal adjacent tissues, while TPM1 was downregulated. The luciferase activity was reduced following transfection with miR-96 mimics and luciferase reporter plasmid containing the wild-type sequence of the 3'-untranslated region of TPM1. Furthermore, knockdown of miR-96 combined with oxaliplatin reduced the viability and induced apoptosis of CRC cells, which was further verified by decreased expression of Bcl-2 and the increased expression of TPM1 and BAX. Taken together, the downregulation of miR-96 enhanced the sensitivity of CRC cells to oxaliplatin.
ABSTRACT
BACKGROUND: Oxaliplatin (OXA)-based chemotherapy is generally used to treat human cancers, whereas OXA resistance is a main obstacle for the treatment of colorectal cancer (CRC). Evidence has shown that tanshinone IIA (Tan IIA) could induce apoptosis in CRC cells. However, the role of combination of OXA and Tan IIA on OXA-resistance CRC cells remains unknown. Thus, this study aimed to investigate the effects of Tan IIA in combination with OXA on OXA-resistance CRC cells. METHODS: MTT assay, Ki67 immunofluorescence staining and flow cytometry were used to detect viability, proliferation and apoptosis in OXA-resistant cell line SW480/OXA, respectively. The expressions of Bcl-2, Bax, active caspase 3, p-Akt and p-ERK in SW480/OXA cells were detected with Western blot. In vivo animal study was performed finally. RESULTS: In this study, the inhibitory effects of OXA on the proliferation and invasion of SW480/OXA cells were significantly enhanced by Tan IIA. In addition, Tan IIA obviously enhanced the anti-apoptosis effects of OXA on SW480/OXA cells via decreasing the levels of Bcl-2, p-Akt and p-ERK, and increasing the levels of Bax and active caspase 3. In vivo experiments confirmed that Tan IIA enhanced OXA sensitivity in SW480/OXA xenograft model. CONCLUSION: We found that Tan IIA could reverse OXA resistance in OXA-resistance CRC cells. Therefore, OXA combined with Tan IIA might be considered as a therapeutic approach for the treatment of OXA-resistant CRC.
ABSTRACT
PURPOSE: To investigate the therapeutic effects of protease-activated receptor 2 (PAR-2) agonist SLIGRL-NH2 on loperamide-induced Sprague-Dawley (SD) rat constipation animal models. MATERIALS AND METHODS: Loperamide was injected subcutaneously to induce constipation twice a day for 3 days. SD rats (n = 30) were randomly divided into five groups: non-constipation group (control, n = 6), constipation group (constipation, n = 6), constipation + SLIGRL-NH2 low-dosage group (SLIGRL-NH2 low, n=6), constipation + SLIGRL-NH2 high-dosage group (SLIGRL-NH2 high, n = 6), and constipation + prucalopride (positive control, n = 6). The SLIGRL-NH2 low group and SLIGRL-NH2 high group were administered with 2.5 µmol/kg and 5 µmol/kg SLIGRL-NH2, respectively, and the prucalopride group received 2 mg/kg prucalopride. The control and constipation group received 1× PBS under the same pattern. SLIGRL-NH2 and prucalopride were orally administrated once daily for 7 days. On the final day of oral administration, food intake, water intake, the number of stool pellets, weight, and fecal water content was calculated; moreover, the colons of rats in different groups were collected and histological features were examined by hematoxylin and eosin staining; furthermore, the expression of anoctamin-1 was determined by Immunohistochemical methods, and the expressions of c-kit and PAR-2 were examined using real-time quantitative polymerase chain reaction and Western blot methods; finally, the expressions of neurotransmitter vasoactive intestinal peptide (VIP) and substance P (SP) were examined using enzyme-linked immuno-sorbent assay methods. RESULTS: The feeding and excretion behaviors, intestinal transit ratio, and the histological feature of the colon in the constipated rats were all improved by SLIGRL-NH2 treatment; moreover, SLIGRL-NH2 treatment induced significant increase in the expression of PAR-2 and also increased number of interstitial Cajal cells. Furthermore, SLIGRL-NH2 also decreased the contents of the inhibitory neurotransmitter VIP and increased the expression of the excitatory neurotransmitter SP. High dose of SLIGRL-NH2 has shown similar anti-constipation effects as prucalopride. CONCLUSION: These results suggested that SLIGRL-NH2 can enhance gastrointestinal transit and alleviate in rats with loperamide-induced constipation.
