14-o-phosphonooxymethyltriptolide and Disease-Models--Animal

There is an urgent need for novel and effective treatment options for acute myeloid leukemia (AML). Triptolide, a diterpenoid tri-epoxide compound isolated from the herb Tripterygium wilfordii and its water-soluble pro-drug-Minnelide have shown promising anti-cancer activity. A recent clinical trial for patients with solid tumors confirmed the safety and efficacy at biologically equivalent doses of 0.2 mg/kg/day and lower.. Cell viability of multiple AML cell lines as well as patient apheresis samples were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) based assay. Apoptosis was evaluated by estimating the amount of cleaved caspase. AML cell line (THP1-Luc) was implanted in immunocompromised mice and treated with indicated doses of Minnelide. Leukemic burden before and after treatment was evaluated by imaging in an In Vivo Imaging System (IVIS).. In the current study, we show that Minnelide, at doses below maximum tolerated dose (MTD) demonstrates leukemic clearance of both primary AML blasts and luciferase expressing THP-1 cells in mice. In vitro, multiple primary AML apheresis samples and AML cell lines (THP-1, KG1, Kasumi-1, HL-60) were sensitive to triptolide mediated cell death and apoptosis in low doses. Treatment with triptolide led to a significant decrease in the colony forming ability of AML cell lines as well as in the expression of stem cell markers. Additionally, it resulted in the cell cycle arrest in the G1/S phase with significant downregulation of c-Myc, a major transcriptional regulator mediating cancer cell growth and stemness.. Our results suggest that Minnelide, with confirmed safety and activity in the clinic, exerts a potent anti-leukemic effect in multiple models of AML at doses easily achievable in patients.

Topics: Animals; Apoptosis; Biomarkers, Tumor; Cell Cycle Checkpoints; Cell Line, Tumor; Disease Models, Animal; Disease Progression; Diterpenes; Down-Regulation; Drug Evaluation, Preclinical; Epoxy Compounds; Humans; Leukemia, Myeloid, Acute; Mice; Neoplastic Stem Cells; Organophosphates; Phenanthrenes; Proto-Oncogene Proteins c-myc; Tumor Burden; Tumor Stem Cell Assay

Resident fibroblasts that contact tumor epithelial cells (TEC) can become irreversibly activated as cancer-associated-fibroblasts (CAF) that stimulate oncogenic signaling in TEC. In this study, we evaluated the cross-talk between CAF and TEC isolated from tumors generated in a mouse model of KRAS/mut p53-induced pancreatic cancer (KPC mice). Transcriptomic profiling conducted after treatment with the anticancer compound Minnelide revealed deregulation of the TGFβ signaling pathway in CAF, resulting in an apparent reversal of their activated state to a quiescent, nonproliferative state. TEC exposed to media conditioned by drug-treated CAFs exhibited a decrease in oncogenic signaling, as manifested by downregulation of the transcription factor Sp1. This inhibition was rescued by treating TEC with TGFβ. Given promising early clinical studies with Minnelide, our findings suggest that approaches to inactivate CAF and prevent tumor-stroma cross-talk may offer a viable strategy to treat pancreatic cancer.

Topics: Animals; Apoptosis; Cancer-Associated Fibroblasts; Carcinogenesis; Carcinoma, Pancreatic Ductal; Cell Proliferation; Disease Models, Animal; Diterpenes; Epithelial Cells; Epoxy Compounds; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Inbred C57BL; Mutation; Organophosphates; Pancreatic Neoplasms; Phenanthrenes; Proto-Oncogene Proteins p21(ras); Signal Transduction; Transforming Growth Factor beta; Tumor Cells, Cultured; Tumor Suppressor Protein p53

Pancreatic adenocarcinoma is the fourth leading cause for cancer-related mortality with a survival rate of less than 5%. Late diagnosis and lack of effective chemotherapeutic regimen contribute to these grim survival statistics. Relapse of any tumor is largely attributed to the presence of tumor-initiating cells (TIC) or cancer stem cells (CSC). These cells are considered as hurdles to cancer therapy as no known chemotherapeutic compound is reported to target them. Thus, there is an urgent need to develop a TIC-targeted therapy for pancreatic cancer.. We isolated CD133(+) cells from a spontaneous pancreatic ductal adenocarcinoma mouse model and studied both surface expression, molecular markers of pancreatic TICs. We also studied tumor initiation properties by implanting low numbers of CD133(+) cells in immune competent mice. Effect of Minnelide, a drug currently under phase I clinical trial, was studied on the tumors derived from the CD133(+) cells.. Our study showed for the first time that CD133(+) population demonstrated all the molecular markers for pancreatic TIC. These cells initiated tumors in immunocompetent mouse models and showed increased expression of prosurvival and proinvasive proteins compared to the CD133(-) non-TIC population. Our study further showed that Minnelide was very efficient in downregulating both CD133(-) and CD133(+) population in the tumors, resulting in a 60% decrease in tumor volume compared with the untreated ones.. As Minnelide is currently under phase I clinical trial, its evaluation in reducing tumor burden by decreasing TIC as well as non-TIC population suggests its potential as an effective therapy.

Topics: AC133 Antigen; Animals; Antigens, CD; Antigens, Surface; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Cell Transformation, Neoplastic; Disease Models, Animal; Diterpenes; Epoxy Compounds; Gene Expression; Glycoproteins; Immunophenotyping; Mice; Mice, Transgenic; Neoplastic Stem Cells; NF-kappa B; Organophosphates; Pancreatic Neoplasms; Peptides; Phenanthrenes; Phenotype