Mutation and genomic amplification of the PIK3CA proto-oncogene in pituitary adenomas

The tumorigenesis of pituitary adenomas is poorly understood. Mutations of the PIK3CA proto-oncogene, which encodes the p110-α catalytic subunit of PI3K, have been reported in various types of human cancers regarding the role of the gene in cell proliferation and survival through activation of the PI3K/Akt signaling pathway. Only one Chinese study described somatic mutations and amplification of the PIK3CA gene in a large series of pituitary adenomas. The aim of the present study was to determine genetic alterations of PIK3CA in a second series that consisted of 33 pituitary adenomas of different subtypes diagnosed by immunohistochemistry: 6 adrenocorticotropic hormone-secreting microadenomas, 5 growth hormone-secreting macroadenomas, 7 prolactin-secreting macroadenomas, and 15 nonfunctioning macroadenomas. Direct sequencing of exons 9 and 20 assessed by qPCR was employed to investigate the presence of mutations and genomic amplification defined as a copy number ≥4. Previously identified PIK3CA mutations (exon 20) were detected in four cases (12.1%). Interestingly, the Chinese study reported mutations only in invasive tumors, while we found a PIK3CA mutation in one noninvasive corticotroph microadenoma. PIK3CA amplification was observed in 21.2% (7/33) of the cases. This study demonstrates the presence of somatic mutations and amplifications of the PIK3CA gene in a second series of pituitary adenomas, corroborating the previously described involvement of the PI3K/Akt signaling pathway in the tumorigenic process of this gland.

MTP -493G/T gene polymorphism is associated with steatosis in hepatitis C-infected patients

The reduction of hepatic microsomal transfer protein (MTP) activity results in fatty liver, worsening hepatic steatosis and fibrosis in chronic hepatitis C (CHC). The G allele of the MTP gene promoter, -493G/T, has been associated with lower transcriptional activity than the T allele. We investigated this association with metabolic and histological variables in patients with CHC. A total of 174 untreated patients with CHC were genotyped for MTP -493G/T by direct sequencing using PCR. All patients were negative for markers of Wilson’s disease, hemochromatosis and autoimmune diseases and had current and past daily alcohol intake lower than 100 g/week. The sample distribution was in Hardy-Weinberg equilibrium. Among subjects with genotype 1, 56.8 percent of the patients with fibrosis grade 3+4 presented at least one G allele versus 34.3 percent of the patients with fibrosis grade 1+2 (OR = 1.8; 95 percentCI = 1.3-2.3). Logistic regression analysis with steatosis as the dependent variable identified genotypes GG+GT as independent protective factors against steatosis (OR = 0.4, 95 percentCI = 0.2-0.8; P = 0.01). The results suggest that the presence of the G allele of MTP -493G/T associated with lower hepatic MTP expression protects against steatosis in our CHC patients.

Diabetes mellitus: new therapeutic approaches to treat an old disease

Diabetes mellitus is a widespread disease whose frequency increases constantly and is expected to reach alarming levels by the year 2025. Introduction of insulin therapy represented a major breakthrough; however, a very strict regimen is required to maintain blood glucose levels within the normal range and to prevent or postpone chronic complications associated with this disease. Frequent hyper- and hypoglycemia seriously affect the quality of life of these patients. Reversion of this situation can only be achieved through whole organ (pancreas) transplant or pancreatic islet transplant, the former being a high-risk surgical procedure, while the latter is a much simpler and may be accomplished in only 20-40 min. The advantages and perspectives of islet cell transplantation will be discussed, in the light of tissue engineering and gene therapy. Ongoing research carried out in our laboratory, aimed at developing clinical cell and molecular therapy protocols for diabetes will also be focused