sirolimus and cyclopamine

In the liver, energy homeostasis is mainly regulated by mechanistic target of rapamycin (mTOR) signalling, which influences relevant metabolic pathways, including lipid metabolism. However, the Hedgehog (Hh) pathway is one of the newly identified drivers of hepatic lipid metabolism. Although the link between mTOR and Hh signalling was previously demonstrated in cancer development and progression, knowledge of their molecular crosstalk in healthy liver is lacking. To close this information gap, we used a transgenic mouse model, which allows hepatocyte-specific deletion of the Hh pathway, and in vitro studies to reveal interactions between Hh and mTOR signalling. The study was conducted in male and female mice to investigate sexual differences in the crosstalk of these signalling pathways. Our results reveal that the conditional Hh knockout reduces mitochondrial adenosine triphosphate (ATP) production in primary hepatocytes from female mice and inhibits autophagy in hepatocytes from both sexes. Furthermore, in vitro studies show a synergistic effect of cyclopamine and rapamycin on the inhibition of mTor signalling and oxidative respiration in primary hepatocytes from male and female C57BL/6N mice. Overall, our results demonstrate that the impairment of Hh signalling influences mTOR signalling and therefore represses oxidative phosphorylation and autophagy.

Topics: Adenosine Triphosphate; Animals; Autophagy; Drug Synergism; Energy Metabolism; Female; Gene Deletion; Hedgehog Proteins; Hepatocytes; Lipid Metabolism; Liver; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidative Phosphorylation; Sex Factors; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Veratrum Alkaloids

Pancreatic cancer is characterized by near-universal mutations in KRAS. The mammalian target of rapamycin (mTOR), which functions downstream of RAS, has divergent effects on stem cells. In the present study, we investigated the significance of the mTOR pathway in maintaining the properties of pancreatic cancer stem cells. The mTOR inhibitor, rapamycin, reduced the viability of CD133(+) pancreatic cancer cells and sphere formation which is an index of self-renewal of stem-like cells, indicating that the mTOR pathway functions to maintain cancer stem-like cells. Further, rapamycin had different effects on CD133(+) cells compared to cyclopamine which is an inhibitor of the Hedgehog pathway. Thus, the mTOR pathway has a distinct role although both pathways maintain pancreatic cancer stem cells. Therefore, mTOR might be a promising target to eliminate pancreatic cancer stem cells.

Topics: AC133 Antigen; Animals; Antigens, CD; Cell Line, Tumor; Cell Survival; Glycoproteins; Hedgehog Proteins; Humans; Mice, Inbred BALB C; Mice, Nude; Neoplastic Stem Cells; Pancreatic Neoplasms; Peptides; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Veratrum Alkaloids

Aberrant reactivation of Gli signaling has been described in a wide variety of human cancers and rapamycin can down-regulate Gli pathway in some solid tumors. In this study, we attempt to define the cytotoxic effect of Gli inhibitor on AML cells. And the regulation action of rapamycin on Gli in AML cells also has been assessed. Gli inhibitor GANT61 caused growth arrest and apoptosis in AML cells. Rapamycin decreased not only the Gli protein and mRNA expressions but also expression of the Gli-luciferase reporter in AML cells. Synergism effect between GANT61 and rapamycin was found in Kasumi-1, HL-60 and U937 cell lines. The results suggest that aberrant Gli activation is a feature of some myeloid leukemic cells and Gli activiation can be down-regulated by rapamycin.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Drug Evaluation, Preclinical; Drug Synergism; Gene Expression Regulation, Leukemic; HL-60 Cells; Humans; K562 Cells; Leukemia, Myeloid; Pyridines; Pyrimidines; RNA, Small Interfering; Sirolimus; Transcription Factors; U937 Cells; Veratrum Alkaloids; Zinc Finger Protein GLI1

Pancreatic cancers contain exclusively tumorigenic cancer stem cells (CSCs), which are highly resistant to chemotherapy, resulting in a relative increase in CSC numbers during gemcitabine treatment. Signaling through sonic hedgehog and mammalian target of rapamycin (mTOR), respectively, may be essential for CSC self-renewal and could represent putative targets for novel treatment modalities.. We used in vitro and in vivo models of pancreatic cancer to examine the effects of sonic hedgehog inhibition (cyclopamine/CUR199691) and mTOR blockade (rapamycin) on the tumorigenic CSC population.. Surprisingly, neither cyclopamine nor rapamycin alone or as supplements to chemotherapy were capable of effectively diminishing the CSC pool. Only the combined inhibition of both pathways together with chemotherapy reduced the number of CSCs to virtually undetectable levels in vitro and in vivo. Most importantly, in vivo administration of this triple combination in mice with established patient-derived pancreatic tumors was reasonably tolerated and translated into significantly prolonged long-term survival.. The combined blockade of sonic hedgehog and mTOR signaling together with standard chemotherapy is capable of eliminating pancreatic CSCs. Further preclinical investigation of this promising approach may lead to the development of a novel therapeutic strategy to improve the devastating prognosis of patients with pancreatic cancer.

Topics: AC133 Antigen; Animals; Antigens, CD; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Deoxycytidine; Drug Resistance, Neoplasm; Female; Gemcitabine; Glycoproteins; Hedgehog Proteins; Humans; Mice; Mice, Nude; Neoplasm Transplantation; Neoplastic Stem Cells; Pancreatic Neoplasms; Peptides; Protein Kinases; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Veratrum Alkaloids