Circular RNA RHOT1 Regulates miR-142-5p/CCND1 to Participate in Chondrocyte Autophagy and Proliferation in Osteoarthritis.

Background: Osteoarthritis (OA) serves as one of the most prevalent types of joint disorders and is a leading cause of symptoms of stiffness, swelling, and arthralgia. Circular RNAs (circRNAs) have been reported to participate in various cellular processes by competing with microRNAs. Meanwhile, cyclinD1 (CCND1) is a key cell cycle regulatory protein and plays a crucial role in OA progression. Nevertheless, the function of circRHOT1 in the modulation of OA progression is still obscure. Here, we explored the effect of circRHOT1 on autophagy and extracellular matrix (ECM) in OA. Methods: The expression of circRHOT1 and autophagy markers was detected in OA samples. The effect of circRHOT1 on OA was analyzed in the OA rat model. The function of circRHOT1 in the regulation of OA was assessed by CCK-8, colony formation, flow cytometry analysis, quantitative real-time PCR, Western blot analysis, and luciferase reporter gene assay in chondrocytes. Results: We observed that autophagy markers, including LC3 and beclin1, were repressed in clinical OA samples. The expression of circRHOT1 and CCND1 was induced but the miR-142-5p expression was reduced in clinical OA samples. The miR-142-5p expression was negatively correlated with circRHOT1 and CCND1, and the circRHOT1 expression was positively associated with CCND1 in clinical OA samples. Meanwhile, the apoptosis was induced in OA rats but the depletion of circRHOT1 could block the phenotype in the rats. The articular cartilage degeneration was promoted in OA rats, while the knockdown of circRHOT1 repressed the degeneration. The serum levels of CTX-II and COMP were increased in OA rats, and the silencing of circRHOT1 downregulated levels of these proteins. In addition, the expression of collagen II and aggrecan was promoted by the depletion of circRHOT1 in the OA rats. Significantly, the expression of LC3 and beclin1 was suppressed in OA rats, in which the knockdown of circRHOT1 could reverse the effect. Moreover, the depletion of circRHOT1 repressed the cell viability and proliferation but induced apoptosis of chondrocytes. The expression levels of LC3, beclin1, collagen II, and aggrecan were induced by circRHOT1 knockdown. Mechanically, circRHOT1 was able to enhance the CCND1 expression by sponging miR-142-5p in chondrocytes. The overexpression of CCND1 or the inhibition of miR-142-5p reversed circRHOT1 depletion-mediated chondrocyte phenotypes. Conclusions: Circular RNA RHOT1 enhances the CCND1 expression by sponging miR-142-5p to inhibit chondrocyte autophagy and promote chondrocyte proliferation in osteoarthritis. Our findings provided a promising therapeutic target for OA.

[Antitumor effect of recombinant immunotoxin EGF-TCS in nude mice bearing human hepatocellular carcinoma].

OBJECTIVE: To evaluate the anti-tumor effect of recombinant toxin EGF-TCS against transplanted human hepatocellular carcinoma in nude mice. METHODS: Human hepatocellular carcinoma BEL-7,402 cells were inoculated subcutaneously in the right axillary region of nude mice, and 6 days later, EGF-TCS was injected intravenously at 100, 50, and 25 microg/kg. The mice were executed on the next day of drug withdrawal and the tumors were weighed and the tumor inhibition rate calculated. Immunohistochemistry was also performed on the tumor tissues to provide clue for the possible pathways of tumor inhibition. RESULTS: EGF-TCS markedly inhibited the tumor growth in nude mice, with a tumor inhibition rate of 71.3%, 60.87% and 45.22% corresponding to EGF-TCS dosage of 100, 50, and 25 microg/kg, respectively. Variance analysis suggested that EGF-Linker-TCS could significantly inhibit the tumor growth in the mice (F=8.712, P=0.006), and immunohistochemistry showed significantly inhibited angiogenesis in the tumors by EGF-TCS. No blood vessels were found in the tumor tissues in high dosage group, and there were also reduced blood vessels in the other two smaller dose groups in comparison with the untreated model group, indicating that EGF-TCS inhibited tumor growth and migration by inhibiting tumor angiogenesis. CONCLUSION: EGF-TCS can inhibit the growth of solid tumors in nude mice, suggesting the potential value of this preparation in cancer therapy.

[Gene cloning, expression and purification of fusion protein epidermal growth factor-linker-trichosanthin].

OBJECTIVE: To construct a recombinant expression vector of the fusion protein epidermal growth factor (EGF)-Linker-trichosanthin (TCS) and achieve its expression in E. coli to obtain purified EGF-linker-TCS fusion protein. METHODS: The gene fragments of EGF-linker were amplified by PCR and inserted into the expression plasmid PQE30-TCS, followed by transformation of the recombinant plasmid into E. coli M15 for expression of the fusion protein. Ni-FF column chromatography was utilized for purification of the expressed product. RESULTS: The recombinant plasmid PQE30-EGF-linker-TCS was stably and highly expressed in E. coli M15. The expressed product existed in the form of soluble protein accounting for about 40% of total cellular protein and reached a purity of above 95% after purification with Ni-FF column chromatography. CONCLUSION: The recombinant plasmid PQE30/EGF-linker-TCS has been successfully constructed, which provides a basis for further structural and functional study of EGF and TCS and their potential clinical application for cancer therapy.