PubMed · 15954435
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
Kazuyoshi Yonezawa. 2005. [Rapamycin].. https://pubmed.ncbi.nlm.nih.gov/15954435/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
OBJECTIVE: Comparative genomic hybridization has frequently detected amplification of chromosome 5p in cervical cancer, but candidate cancer genes within the region are rarely known. Therefore, we pursued to identify potential candidate gene related to cervical cancer development. METHODS: A series of 128 cervical tumor samples were examined by semi-quantitative fluorescent differential PCR for copy number changes on three candidate genes (PRKAA1, CTNND2 and POLS) mapped to chromosome 5p and one gene (ERBIN) mapped to chromosome 5q12.3. The impact of gene copy number was later analyzed in relation to HPV infection, tumor stage or tumor radiosensitivity. RESULTS: DNA copy numbers of PRKAA1, CTNND2 and ERBIN were significantly different from normal controls (P < 0.05). DNA copy number changes did not correlate with HPV infection, tumor stages or tumor radiosensitivity. Using RT-PCR, PRKAA1 mRNA expression in seven tumor samples with known 5p amplification was amplified from 3- to 15-fold. Over-expression of PRKAA1 was further confirmed by immunohistochemical staining on 125 paraffin-embedded cervical cancer tissues. The expression level in cervical tumor was significantly higher than that in normal epithelium (P < 0.001). CONCLUSIONS: PRKAA1 gene codes for the catalytic alpha 1 subunit of the AMP-activated protein kinase which is an important cellular metabolic stress regulator. It might assist tumor cells growth under stress. Thus, PRKAA1 may be one of the potential candidate genes for cervical carcinogenesis.
The cytosolic protein Bax plays a key role in apoptosis by migrating to mitochondria and releasing proapoptotic proteins from the mitochondrial intermembrane space. The present study investigates the movement of Bax in isolated rat neonatal cardiomyocytes subjected to simulated ischaemia (minus glucose, plus cyanide), using green fluorescent protein-tagged Bax as a means of imaging Bax movements. Simulated ischaemia induced Bax translocation from the cytosol to mitochondria, commencing within 20 min of simulated ischaemia and progressing for several hours. Under the same conditions, there was an increase in the active, phosphorylated forms of p38 MAPK (mitogen-activated protein kinase) and AMPK (AMP-activated protein kinase). The AMPK activators AICAR (5-aminoimidazole-4-carboxamide ribonucleoside) and metformin also stimulated Bax translocation. Inhibition of p38 MAPK with SB203580 attenuated the phosphorylation of the downstream substrates, MAPK-activated protein kinases 2 and 3, but not that of the upstream MAPK kinase 3, nor of AMPK. Under all conditions (ischaemia, AICAR and metformin), SB203580 blocked Bax translocation completely. It is concluded that Bax translocation to mitochondria is an early step in ischaemia and that it occurs in response to activation of p38 MAPK downstream of AMPK.
Germline mutations in the LKB1 gene are responsible for Peutz-Jeghers syndrome (PJS), which is characterized by gastrointestinal hamartomas and increasing risk of cancer. Mice with Lkb1(+/-) mutation develop gastric hamartomas after >20 weeks of age, and hepatocellular adenomas and carcinomas >30 weeks. It has been reported that, in PJS patients, carcinomas progressed from hamartomas contain p53 mutations, and that LKB1 regulates p53-dependent apoptosis. To investigate the roles of LKB1 and p53 mutations in tumorigenesis, we constructed compound mutant mice of Lkb1 and p53 genes. In the Lkb1(+/-)p53(-/-) mice, formation of gastric hamartomas and hepatic tumors was accelerated. However, histopathology of hamartomas was similar between Lkb1(+/-)p53(-/-) and Lkb1(+/-) mice, and Lkb1 genotype remained heterozygous, suggesting that the p53 mutation affected hamartoma initiation. Contrary to the heterozygous hamartomas in the stomach and duodenum, the hepatic adenomas in Lkb1(+/-)p53(-/-) mice showed loss of Lkb1 heterozygosity (LOH), suggesting that lack of p53 stimulated Lkb1 LOH and tumor initiation in the liver. Taken together, these results indicate that lack of p53 causes earlier onsets of gastric hamartomas and hepatic tumors in Lkb1(+/-)p53(-/-) mice.