Analysis of TP53 gene and particular infrastructural alterations in invasive ductal mammary carcinoma.

This study was conducted in order to determine the mutational status of TP53 gene and to determine some particular aspects from ultrastructural level in invasive mammary ductal carcinoma. The cellular signaling pathway involving the TP53 gene acts in biological deoxyribonucleic acid (DNA) repair processes and cell cycle arrest following a signal transmitted to the p53 protein when posttranslational changes occur in the cell due to stress induced in the cell by both intrinsic and extrinsic factors. Cellular stress activates the transcription factor function of the protein that initiates, as the case may be, either DNA repair or programmed cell death (apoptosis). The TP53 gene is commonly mutated in many human cancers and also has a highly polymorphic grade. To determine the mutational status of the exons 4-9 of the TP53 gene, we used extracted DNA from fresh breast tissue, and we analyzed it through direct sequencing. In mammary carcinoma, the mutation frequency of TP53 is running between 20-40% and, in regards the polymorphism, at least 14 different forms were identified, that are associated with cancer risk. The mutation type distribution showed a predominance of deletions and a reduced frequency of substitutions comparing with International Agency for Research on Cancer (IARC) database. Taken in consideration the importance of the tumor associated stroma in tumor development, we have also investigated some particular aspects at the infrastructural level of invasive mammary ductal carcinoma, notably concerning telocytes as tumor stroma interstitial cells by transmission electron microscopy analysis.

Molecular analysis of BRCA1 and BRCA2 genes by next generation sequencing and ultrastructural aspects of breast tumor tissue.

In this paper, we focus our interest on the dynamics alterations of the tumor-stroma interface at the ultrastructural level and to detect BRCA1 and BRCA2 mutations using next generation sequencing (NGS) of breast tumor tissue. Electron microscopic investigation revealed some peculiar infrastructural alterations of the tumor cells per se as well as of the tumor-stroma interface: invadopodia, shedding microvesicles, altered morphology and reduced number of telocytes, different abnormalities of the microvasculature. Tumor suppressor genes BRCA1 and BRCA2 are the genes with most hereditary predisposition to breast and ovarian cancer. An early identification of mutation within these genes is essential for determining classification and therapeutic approach to patients. Genetic tests used to determine mutations in BRCA1 and BRCA2 genes are laborious analysis methods which include, among others, NGS. We analyzed a total of eight samples, in which genomic DNA was amplified using Ion AmpliSeq panel BRCA1 and BRCA2. DNA libraries were created, amplified and sequenced with Ion Torrent Personal Genome Machine. The bio-information data obtained allow us to detect all known pathogenic mutation and uncertain polymorphisms.

Particular molecular and ultrastructural aspects in invasive mammary carcinoma.

Electron microscopic investigations of invasive mammary carcinoma tumors revealed that intercellular junctions, namely desmosomes are severely altered; some desmosomes became internalized. Tumor cells, especially by their invadopodia, generate and disseminate membrane vesicles, including exosomes, inside of peritumoral stroma. Telocytes, a new described interstitial/stromal cell phenotype, considered to play important roles in cell signaling, exhibited a reduced number of hetero-cellular contacts, which suggests a possible perturbation of tissular homeostasis modulation. Signaling PIK3/Akt pathway plays an important role both in carcinogenesis and in proliferation, differentiation, and cell survival. Alteration of this pathway has been observed in many human cancers, often involving an increase in the activity of PIK3CA, p110α catalytic subunit of PI3K. Our study confirms the high prevalence of PIK3CA mutations in breast cancer. In accordance with the results of the largest previous studies, 87.5% of mutations detected by DNA direct sequencing were hot spot mutations, most of them located in the kinase domain. High percentage of mutations detected by high-resolution melting makes the assay an attractive choice for mutation scanning, especially, in samples with low percentage of tumor cell.