sirolimus and Peutz-Jeghers-Syndrome

Topics: AMP-Activated Protein Kinase Kinases; Antineoplastic Agents; Base Sequence; Everolimus; Humans; Male; Middle Aged; Mutation; Pancreatic Neoplasms; Peutz-Jeghers Syndrome; Protein Serine-Threonine Kinases; Sirolimus; TOR Serine-Threonine Kinases

Germline mutations in LKB1 cause Peutz-Jeghers syndrome (PJS), an autosomal dominant disorder with a predisposition to gastrointestinal polyposis and cancer. Hyperactivation of mTOR-signaling has been associated with PJS. We previously reported that rapamycin treatment of Lkb1(+/-) mice after the onset of polyposis reduced the polyp burden. Here we evaluated the preventive efficacy of rapamycin on Peutz-Jeghers polyposis. We found that rapamycin treatment of Lkb1(+/-) mice initiated before the onset of polyposis in Lkb1(+/-) mice led to a dramatic reduction in both polyp burden and polyp size and this reduction was associated with decreased phosphorylation levels of S6 and 4EBP1. Together, these findings support the use of rapamycin as an option for chemoprevention and treatment of PJS.

Topics: AMP-Activated Protein Kinases; Animals; Antibiotics, Antineoplastic; Carrier Proteins; Disease Models, Animal; Germ-Line Mutation; Intestinal Polyps; Mice; Mice, Knockout; Peutz-Jeghers Syndrome; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Protein Serine-Threonine Kinases; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases

Patients with Peutz-Jeghers syndrome (PJS) are affected by hamartomatous intestinal polyposis and increased risk of cancers in multiple organs caused by germline mutations in the tumour suppressor gene LKB1. Murine models that recapitulate aspects of PJS have been created. Here we examine the therapeutic effect of rapamycin, a macrolide with anti-tumourigenic and anti-angiogenic properties, in reducing tumour incidence in a large cohort of Lkb1(+/-) mice. To study the influence of early intervention, the animals were dosed with rapamycin from the age of 8 weeks, well before the onset of polyposis. These mice continued to receive the drug, which was well tolerated, throughout their lives. At sacrifice, we observed a reduction in gastric tumour burden in the rapamycin-treated mice (p = 0.0001) compared with age- and sex-matched controls. Treated animals also have a lower number of polyps per mouse than controls. In the polyps from the treated mice, phosphorylation of ribosomal p70 S6 kinase was maintained, while the phosphorylation of AKT at serine-473 was elevated, suggesting that mTORC1 function is maintained at this dosage. Despite this, a significant reduction in microvessel density was seen in polyps from the rapamycin-treated mice compared to those from the control mice (p = 5 x 10(-5)), suggesting that the anti-angiogenic effect of rapamycin played a role in polyp reduction. Overall, we demonstrated that prolonged oral administration of rapamycin from an early age is effective in lowering tumour burden in the Lkb1(+/-) mice without evident side effects.

Topics: Administration, Oral; AMP-Activated Protein Kinases; Animals; Antibiotics, Antineoplastic; Blotting, Western; Germ-Line Mutation; In Situ Hybridization; In Situ Nick-End Labeling; Mice; Mice, Inbred C57BL; Mice, Knockout; Microvessels; Neovascularization, Pathologic; Peutz-Jeghers Syndrome; Protein Serine-Threonine Kinases; Reverse Transcriptase Polymerase Chain Reaction; Sirolimus; Tumor Burden

Peutz-Jeghers syndrome (PJS) is a familial cancer disorder due to inherited loss of function mutations in the LKB1/ STK11 serine/threonine kinase. PJS patients develop gastrointestinal hamartomas with 100% penetrance often in the second decade of life, and demonstrate an increased predisposition toward the development of a number of additional malignancies. Among mitogenic signaling pathways, the mammalian-target of rapamycin complex 1 (mTORC1) pathway is hyperactivated in tissues and tumors derived from LKB1-deficient mice. Consistent with a central role for mTORC1 in these tumors, rapamycin as a single agent results in a dramatic suppression of preexisting GI polyps in LKB1+/- mice. However, the key targets of mTORC1 in LKB1-deficient tumors remain unknown. We demonstrate here that these polyps, and LKB1- and AMPK-deficient mouse embryonic fibroblasts, show dramatic up-regulation of the HIF-1alpha transcription factor and its downstream transcriptional targets in an rapamycin-suppressible manner. The HIF-1alpha targets hexokinase II and Glut1 are up-regulated in these polyps, and using FDG-PET, we demonstrate that LKB1+/- mice show increased glucose utilization in focal regions of their GI tract corresponding to these gastrointestinal hamartomas. Importantly, we demonstrate that polyps from human Peutz-Jeghers patients similarly exhibit up-regulated mTORC1 signaling, HIF-1alpha, and GLUT1 levels. Furthermore, like HIF-1alpha and its target genes, the FDG-PET signal in the GI tract of these mice is abolished by rapamycin treatment. These findings suggest a number of therapeutic modalities for the treatment and detection of hamartomas in PJS patients, and potential for the screening and treatment of the 30% of sporadic human lung cancers bearing LKB1 mutations.

Topics: AMP-Activated Protein Kinases; Animals; Cell Proliferation; Disease Models, Animal; Down-Regulation; Fibroblasts; Glucose; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Mechanistic Target of Rapamycin Complex 1; Mice; Multiprotein Complexes; Peutz-Jeghers Syndrome; Positron-Emission Tomography; Protein Kinases; Protein Serine-Threonine Kinases; Proteins; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Transcription Factors; Tumor Burden; Up-Regulation

Peutz-Jeghers syndrome (PJS) is a unique disorder characterized by the development of hamartomas in the gastrointestinal tract as well as increased risks for variety of malignancies. Germ-line mutations of LKB1 cause PJS. We have generated Lkb1+/- mice, which model human PJS. Rapamycin and its analogues are promising preventive and therapeutic agents that specifically inhibit signaling from mammalian target of rapamycin (mTOR). Hyperactivation of mTOR signaling has been associated with PJS. The objective of the study is to investigate the efficacy of mTOR inhibition in suppressing Peutz-Jeghers polyposis in Lkb1+/- mice.. We initiated a trial of rapamycin in Lkb1+/- mice at 9 months of age (after the onset of polyposis) at the dose of 2 mg/kg/d for a 2-month period. We assessed the efficacy of rapamycin by measuring polyp sizes and tumor burden. To examine the effect of rapamycin on mTOR signaling, phosphorylation levels of S6 were evaluated by immunostaining.. We observed a significant decrease in mean tumor burden (Student's t test, P = 0.023) as well as total tumor burden in rapamycin-treated group compared with control group. Comparison of the polyp size observed in both rapamycin-treated and control groups showed that rapamycin efficiently decreased the tumor burden of large polyps (> 8 mm). This inhibition of rapamycin was associated with a decrease in phosphorylated S6 levels in the polyps.. Rapamycin effectively suppresses Peutz-Jeghers polyposis in a mouse model, suggesting that rapamycin or its analogues may represent a new targeted therapy for the treatment of PJS.

Topics: AMP-Activated Protein Kinases; Animals; Immunohistochemistry; Immunosuppressive Agents; Mice; Mice, Knockout; Peutz-Jeghers Syndrome; Protein Kinases; Protein Serine-Threonine Kinases; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases