Despite the initial enthusiasm following the discovery of the association of BRCA germline mutations with hereditary breast and/or ovarian cancer, in many families affected by the syndrome no pathogenic mutations were detected in the two genes, although exhaustively searched. Many other genes have also been implicated due to their role in the same pathway of DNA repair where the BRCA1/2 genes are involved: homologous recombination (HR). Among them, PALB2 clearly emerges as the third breast cancer susceptibility gene. Its mutations have been detected in most populations investigated so far, albeit rarely: in 1%-4% of families negative for BRCA mutations, with either partial or complete penetrance. In some populations, PALB2 recurrent mutations have been identified and the estimated hazard risks are comparable to those of BRCA mutations. Since new effective targeted therapeutic options are becoming available ("synthetic lethality" with novel PARP inhibitors, etc.) that are applicable to all those patients with a defect in HR pathway, it is imperative to detect all these candidate patients. Data obtained from laboratory tests in the tumor (simple immunohistochemistry, gene expression analysis, etc.) can assist in the recognition of a specific pattern (BRCA1ness, HRless) so that even patients that look "sporadic" could benefit from these targeted therapies. Therefore, a genetic analysis algorithm is proposed, although with the advent of Next Generation Sequencing it is predicted that in the future most germline genetic alterations and also somatic or epigenetic events in the tumor of these genes will be detected.
Somatic mutations in the PIK3CA gene have been discovered in many human cancers , and their presence correlates to therapy response. Three "hotspot" mutations within the PIK3CA gene are localized in exons 9 and 20. High-resolution melting analysis (HRMA) is a highly sensitive, robust, rapid, and cost-effective mutation analysis technique. We developed a novel methodology for the detection of hotspot mutations in exons 9 and 20 of the PIK3CA gene that is based on a combination of PCR and HRMA. The PIK3CA HRMA assay was evaluated by performing repeatability, sensitivity , and comparison with DNA sequencing studies and was further validated in 129 formalin-fixed paraffin-embedded breast tissue samples: 99 tumors, 20 noncancerous , and 10 fibroadenomas. The developed methodology was further applied in a selected group of 75 breast cancer patients who underwent Trastuzumab treatment. In sensitivity studies , the assay presented a capability to detect as low as 1% of mutated dsDNA in the presence of wtDNA for both exons. In the 99 tumor samples (validation group) , 12/99 (12.1%) exon 9 mutations and 20/99 (20.2%) exon 20 mutations were found. No mutations were found in noncancerous tissues. In fibroadenomas , we report one PIK3CA mutation for the first time. In the selected group , 30/75 (40%) samples were detected as mutants. The PIK3CA HRMA assay is highly sensitive , reliable , cost-effective , and easy-to-perform, and therefore can be used as a screening test in a highthroughput pharmacodiagnostic setting. PIK3CA mutations appear to have a clinical significance.12 Recent studies have shown that PIK3CA mutations can independently hamper the therapeutic response to anti-EGFR biological therapies (panitumumab or cetuximab) in metastatic colorectal cancer 13 and demonstrate resistance to dietary restriction therapies. 14 Moreover, several efforts are underway nowadays to target the PI3K pathway with therapeutic inhibitors.Additionally, keeping in mind that not all patients with HER2-overexpressing metastatic breast cancer respond to Trastuzumab (Herceptin), activated PI3K signaling has been proposed to predict Trastuzumab resistance. 15,16 Loss of the PTEN (Phosphatase and Tensin Homolog) protein has been suggested as a key factor for the development of resistance to this drug. 15,16 However, PTEN loss alone, 16,17 and in combination with phosphorylated AKT expression, 17 proved inadequate to predict response to therapy. Conversely, combining PTEN loss and gain-of-function mutations of the PIK3CA gene, resistance to Trastuzumab was successfully predicted.
BackgroundCollagen XI is a key structural component of the extracellular matrix and consists of three alpha chains. One of these chains, the α1 (XI), is encoded by the COL11A1 gene and is transcribed to four different variants at least (A, B, C and E) that differ in the propensity to N-terminal domain proteolysis and potentially in the way the extracellular matrix is arranged. This could affect the ability of tumor cells to invade the remodeled stroma and metastasize. No study in the literature has so far investigated the expression of these four variants in breast cancer nor does a method for their accurate quantitative detection exist.MethodsWe developed a conventional PCR for the general detection of the general COL11A1 transcript and real-time qPCR methodologies with dual hybridization probes in the LightCycler platform for the quantitative determination of the variants. Data from 90 breast cancer tissues with known histopathological features were collected.ResultsThe general COL11A1 transcript was detected in all samples. The developed methodologies for each variant were rapid as well as reproducible, sensitive and specific. Variant A was detected in 30 samples (33 %) and variant E in 62 samples (69 %). Variants B and C were not detected at all. A statistically significant correlation was observed between the presence of variant E and lymph nodes involvement (p = 0.037) and metastasis (p = 0.041).ConclusionsWith the newly developed tools, the possibility of inclusion of COL11A1 variants as prognostic biomarkers in emerging multiparameter technologies examining tissue RNA expression should be further explored.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1725-8) contains supplementary material, which is available to authorized users.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.