circRERE regulates the expression of GBX2 through miR-1299 and ZC3H13/N6-methyladenosine (m6A) to promote growth and invasion of hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumours in the world. Current studies have shown that circular RNAs (circRNAs) and N6-methyladenosine (m6A) methylation play important roles in the progression of HCC, but further studies are needed to confirm the underlying mechanisms. The expression of circRERE was significantly upregulated in HCC cells, and its downregulation reduced HCC cell viability and invasion while increasing apoptosis. Further study showed that circRERE bound directly to miR- 1299. After downregulating the expression of circRERE, miR-1299 expression was significantly enhanced, while the expression of its downstream target gene GBX2 was suppressed, indicating that circRERE promoted the expression of GBX2 through miR-1299. In addition, downregulation of circRERE expression significantly increased the m6A level of GBX2 and promoted the expression of methyltransferase ZC3H13, while overexpression of ZC3H13 significantly inhibited the expression of GBX2 but increased its m6A methylation. circRERE could regulate the m6A modification of GBX2 through ZC3H13, thus promoting the expression of GBX2.GBX2 was upregulated in HCC tissues, while miR-1299 and ZC3H13 were downregulated. MiR-1299 mimics, ZC3H13 overexpression or GBX2 siRNA significantly inhibited HCC cell viability, promoted apoptosis and reduced invasion; GBX2 exerted the opposite effects and could reverse the regulatory effects of miR-1299 or ZC3H13 on HCC cells. Therefore, circRERE promotes the growth and invasion of HCC cells by regulating the expression of GBX2 through miR-1299 and ZC3H13/m6A, indicating that it is a key circRNA in the progression of HCC.

Interstitial chemotherapy with ricin-loaded thermosensitive hydrogel in pancreatic cancer xenograft.

BACKGROUND: Pancreatic cancer is one of the most aggressive malignancies, and has a poor prognosis. Despite efforts made in multiple fields, there has been little success in improving the disease-free survival rate of patients. This study was undertaken to investigate the effectiveness and feasibility of using intra-tumoral injection of ricin-loaded thermosensitive hydrogel for treatment of pancreatic cancer xenografts, attempting to develop a new treatment for human pancreatic cancer. METHODS: BALB/c-(nu/nu) nude mice were inoculated subcutaneously in the right flank with the human pancreatic cancer cells, SW1990. Fourteen days after inoculation, 32 mice, bearing tumors of volume 1.5-2.0 cm3, were randomly assigned to one of four groups, and given an intra-tumoral injection of: (1) saline; (2) 23% w/w thermosensitive hydrogel alone; (3) ricin, 10 microg/kg; or (4) 10 microg/kg ricin loaded in thermosensitive hydrogel. On day 14 after administration, the tumors were excised to calculate the inhibition rate of tumor growth and perform histopathological examination. Tumor cell apoptosis was detected by flow cytometry, and RT-PCR was performed to evaluate the mRNA expression levels of Bcl2 and Bax. RESULTS: Intra-tumoral injection of ricin-loaded thermosensitive hydrogel resulted in remarkable control of tumor growth. The tumor became necrotic by day 14 after administration. The histological results clearly confirmed that the tumor cells were lysed. The percentage of apoptotic cells detected by flow cytometry was higher in the ricin hydrogel group than in the other groups. Semi-quantitative RT-PCR revealed that the mRNA expression level of Bcl2 was down-regulated whereas Bax was upregulated. CONCLUSIONS: Intra-tumoral injection of ricin-loaded thermosensitive hydrogel may provide an effective approach for interstitial chemotherapy in pancreatic cancer. Inducing apoptosis by downregulating Bcl2 expression and upregulating Bax expression may be a key molecular mechanism.