title: Restoration of silenced Peutz-Jeghers syndrome gene, LKB1, induces apoptosis in pancreatic carcinoma cells.
abstract: Germ line mutations of the LKB1 tumor suppressor gene lead to Peutz-Jeghers syndrome (PJS) with a predisposition to cancer. Previous reports suggest that inactivation of this tumor-suppressor gene plays a role in the pathogenesis of gastrointestinal hamartomas as well as several cancers, including adenocarcinoma of the pancreas. Here, we have shown that LKB1 gene is silenced in the pancreatic cancer cell line AsPC-1, but can be recovered by treatment with the methylation inhibitor, 5-aza-2'-deoxycytidine (5aza2dC). Restoring the level of LKB1 through gene transfer initiated mitochondria-mediated apoptosis in AsPC-1 cells, as evidenced by the release of cytochrome c from the mitochondria. By confocal microscopy as well as biochemical fractionation, we demonstrate that LKB1 is present in the nuclear and mitochondrial compartments of pancreatic cancer cells. Our observations also indicate that although functional p53 is absent, the p53 kin, p73, is inducible by doxorubicin in AsPC-1 cells. This suggests that LKB1-induced apoptosis is p53 independent but might be p73-mediated in the pancreatic tumor cell line, AsPC-1.
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D016923:Cell Death; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D000077209:Decitabine; D004317:Doxorubicin / Q000494:pharmacology; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D006801:Humans; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000235:genetics*; D010580:Peutz-Jeghers Syndrome / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D013347:Subcellular Fractions / Q000378:metabolism; D013997:Time Factors; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins
chemical_list: D000903:Antibiotics, Antineoplastic; D000964:Antimetabolites, Antineoplastic; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D000077209:Decitabine; D004317:Doxorubicin; D017346:Protein Serine-Threonine Kinases; C109790:STK11 protein, human; D000091162:AMP-Activated Protein Kinase Kinases; D001374:Azacitidine