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OBJECTIVE: To explore the efficacy and feasibility of interstitial chemotherapy using thermosensitive gel-coated ricin in hepatoma H22-bearing mice. METHODS: Ricin was purified by chromatography method. The purified ricin was identified by Western blot assay and the purity was determined by high-performance liquid chromatography. BALB/c mice were inoculated subcutaneously in right flank with hepatoma H22 cells. When the tumor size reached about 1.0 cm in diameter, 40 mice were randomly divided into untreated group, thermosensitive gel group, ricin group and thermosensitive gel-coated ricin group. Mice in each group were administered different agents by percutaneous intratumoral injection, including normal saline, thermosensitive hydrogel, ricin and thermosensitive gel-coated ricin. Fifteen days after treatment, the tumors were removed to calculate inhibition rate of tumor growth. The tumor tissues were made into pathological sections to perform histopathological examination. The ultrastructure of tumor tissue was examined by electron microscope examination as well. Blood was collected to detect the hepatic and renal functions. The caspase-3 activity of tumor tissue was determined by using zymologic method with a spectrophotometer. RESULTS: After intratumoral therapy, tumor weight in the thermosensitive gel-coated ricin group was lower than that in the untreated group, with a tumor growth inhibition rate of 71.31%. No obvious hepatic or renal toxicities were detected after thermosensitive gel-coated ricin treatment. Histopathologic observation of the tumor tissue showed massive necrosis and typical apoptosis phenomena, including chromatin margination and apoptotic body. Meanwhile, thermosensitive gel-coated ricin resulted in a significant increase in the caspase-3 activity as compared with the untreated group and the ricin group (P

AIM To investigate the anti-tumor effects and mechanisms of interstitial chemotherapy using intra-tumor injection of thermosensitive gel-coated ricin in nude mice bearing a human hepatoma. METHODS In a subcutaneous mouse model of hepatoma, saline, blank gel, ricin, or thermosensitive gel-coated ricin (TGR) was injected directly into tumors. Fourteen days later, eight mice in each group were sacrificed. The tumors were removed and weighed for calculating tumor growth inhibition rate. Serum alpha-fetoprotein levels, as well as hepatic and renal functions, were measured. Tumor tissue was analyzed under an optical microscope. Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling was used to detect the apoptotic index. Moreover, caspase-3 activity and protein expression in tumor tissue were examined. The survival time of the tumor bearing mice was determined. RESULTS Following interstitial chemotherapy by intra-tumor injection of TGR in nude mice, serum alpha-fetoprotein levels were significantly reduced with no significant impact on hepatic or renal functions. The rate of tumor growth inhibition was 58.5% following a single, local injection. Histological analysis revealed abundant necrosis. The apoptotic index was 45.96 +/- 7.41%. Caspase-3 activity was increased, and caspase-3 protein was significantly activated in tumor cells. Compared to the saline group, the survival time of mice in the TGR group was significantly extended. At the observation terminal time, day 120, two mice were still alive and fully recovered. CONCLUSION Interstitial chemotherapy by intra-tumor injection of TGR was highly efficient and safe for the treatment of nude mice bearing a human hepatoma. Interstitial chemotherapy exhibits inhibitory effects by inducing apoptosis and directly killing tumor cells.

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.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.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.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.