Targeting the Bcl-2 family and P-glycoprotein reverses paclitaxel resistance in human esophageal carcinoma cell line.

Paclitaxel (PTX) is one of the most effective drugs used in the treatment of esophageal cancer, however, paclitaxel resistance represents a key limitation during the treatment process. In this study, we investigated the changes of Bcl-2 family members in the moderate paclitaxel-resistance of esophageal carcinoma EC109/PTX cells both in vitro and in vivo. Moreover, we evaluated the reversal effect using siRNAs and the recombinant inhibitor TW37 targeting Bcl-2, Bcl-XL and Mcl-1. Our findings show that downregulation of Bcl-2, Bcl-XL and Mcl-1 can significantly promote EC109/PTX cell apoptosis and reduce the EC109/PTX cell resistance index (RI). Furthermore, TW37 in combination with a P-gp inhibitor can synergistically reverse the paclitaxel resistance in EC109/PTX cells. These results suggest that targeting of the Bcl-2 family and P-gp is capable of reversing the resistance in EC109/PTX cells and the two-inhibitor combination may be a novel treatment strategy for resistant esophageal cancer.

Anti-proliferative effect of Jesridonin on paclitaxel-resistant EC109 human esophageal carcinoma cells.

Chemoresistance to anticancer drugs is a major obstacle in the efforts to develop a successful treatment strategy for esophageal squamous carcinoma (ESCC). Thus, the exploration of new drugs and treatment strategies for combating resistance are of utmost importance. In this study, we investigated the antitumor drug resistance activity of Jesridonin, a new ent-kaurene diterpenoid, and its possible mechanisms of action using the resistant cancer cell line, EC109/Taxol. MTT assay revealed that Jesridonin had similar IC50 values against EC109 paclitaxel-sensitive cells and drug-resistant EC109/Taxol cells in vitro. In mice, Jesridonin effectively prevented the growth of EC109/Taxol tumor xenografts without exerting any significant toxicity. In addition, Jesridonin significantly inhibited the proliferation of EC109/Taxol cells, induced apoptosis and arrested the cell cycle at the G2/M phase. Furthermore, western blot analysis revealed that Jesridonin upregulated the expression of p53, p53 upregulated modulator of apoptosis (PUMA), cleaved-caspase-9 and cleaved-caspase-3 in EC109/Taxol cells, and downregulated the expression of procaspase-3, procaspase-9 and Bcl-2 in the EC109/Taxol cells in a concentration-dependent manner. Overall, our results demonstrate that Jesridonin may have potential for use in the treatment of paclitaxel-resistant ESCC. The data of the present study may lead to the development of novel treatment strategies for paclitaxel-resistant tumors.

JD enhances the anti-tumour effects of low-dose paclitaxel on gastric cancer MKN45 cells both in vitro and in vivo.

BACKGROUND: Gastric cancer is the third most common cause of cancer mortality worldwide, and paclitaxel (PTX) is one of the most widely used traditional drugs in gastric cancer therapy. However, the response to traditional therapy is limited by acquired chemo-resistance and side effects. Here, we establish a newly designed combination therapy consisting of a compound that is a structural variant of oridonin, i.e. Jesridonin (JD), and low-dose PTX for gastric cancer cells (MKN45) to investigate whether the anti-tumour activity of low-dose PTX could be enhanced when combined with JD. METHODS: The interaction of JD and low-dose PTX was detected in MKN45 cells using the median-effect analysis method. The synergistic effect on cell viability and apoptosis was measured by MTT assay, colony formation assay, transient transfection, flow cytometry and Western blotting. The synergistic in vivo effect of JD plus low-dose PTX was evaluated in nude mouse xenograft models using H&E and TUNEL staining and Western blotting. RESULTS: JD plus low-dose PTX showed a synergistic effect, as the combination indexes were less than 1. Additionally, a synergistic anti-proliferative and pro-apoptotic effect was detected for the combination of JD and low-dose PTX. The apoptotic mechanism induced by JD plus PTX revealed that the combination therapy synergistically activated the mitochondrial pathway. CONCLUSION: Our findings suggest that JD enhances the anti-tumour effect of low-dose PTX on gastric carcinoma cancer cells in both vitro and in vivo, accompanied by activation of the mitochondrial pathway, which may present a more effective therapeutic strategy in gastric cancer treatment.

The Antitumor Activity of the Novel Compound Jesridonin on Human Esophageal Carcinoma Cells.

Jesridonin, a small molecule obtained through the structural modification of Oridonin, has extensive antitumor activity. In this study, we evaluated both its in vitro activity in the cancer cell line EC109 and its in vivo effect on tumor xenografts in nude mice. Apoptosis induced by Jesridonin was determined using an MTT assay, Annexin-V FITC assay and Hoechest 33258 staining. Apoptosis via mitochondrial and death receptor pathways were confirmed by detecting the regulation of MDM2, p53, and Bcl-2 family members and by activation of caspase-3/-8/-9. In addition, vena caudalis injection of Jesridonin showed significant inhibition of tumor growth in the xenograft model, and Jesridonin-induced cell apoptosis in tumor tissues was determined using TUNEL. Biochemical serum analysis of alkaline phosphatase (ALP), alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyl transferase (GGT), total protein (TP) and albumin (ALB) indicated no obvious effects on liver function. Histopathological examination of the liver, kidney, lung, heart and spleen revealed no signs of JD-induced toxicity. Taken together, these results demonstrated that Jesridonin exhibits antitumor activity in human esophageal carcinomas EC109 cells both in vitro and in vivo and demonstrated no adverse effects on major organs in nude mice. These studies provide support for new drug development.