HER-2/neu Gene Codon 655 (Ile/Val) Polymorphism in Breast Carcinoma Patients

BCL-2 (-938C>A), BAX (-248G>A), and HER2 Ile655Val Polymorphisms and Breast Cancer Risk in Indian Population

Breast cancer is the most common carcinoma in women worldwide. The present case-control study was aimed to examine the association of BCL-2 (-938C> A), BAX (-248G > A), and HER2 (I655V i.e. A > G) polymorphisms with breast cancer risk in Indian population. This study enrolled 117 breast cancer cases and 104 controls. BCL-2 (-938C > A), BAX (-248G > A), and HER2 Ile655Val polymorphisms were screened by PCR-RFLP method. There was no significance difference in the allelic and genotype frequency of the BCL-2 (-938C > A) and BAX (-248G > A) polymorphisms between cases and controls. In relation to HER2 Ile655Val polymorphism, the statistical analysis of observed genotypic frequencies showed significant association (p-0.0059). Compared to Ile/Ile (A/A) genotype, frequency of Ile/Val (A/G) genotype was significantly higher among cases than in control group and observed to increase the breast cancer risk (OR, 2.43; 95%CI, 1.32-4.46; p-0.004). The frequency of Val (G) allele was significantly higher in cases as compared to controls (6.83% vs 2.88%, resp.). Compared to Ile (A) allele, significant increase in the risk of breast cancer was observed with Val (G) allele (OR, 2.21; 95% CI, 1.35-3.63; p-0.0016). We observed significant association between HER2 Ile655Val polymorphism and breast cancer risk under the dominant (OR = 2.52; 95% CI: 1.41-4.51; p-0.001) and codominant (OR, 2.24; 95% CI: 1.23-4.09; p-0.008) model. In our study, BCL-2 (-938C > A) and BAX (-248G > A) polymorphism were not found to be associated with breast cancer risk. This present study for the first time shows significant association of HER2 Ile655Val polymorphism with risk of breast cancer in Indian population. Therefore, we suggest that each population need to evaluate its own genetic profile for breast cancer risk that may be helpful for better understanding the racial and geographic differences reported for breast cancer incidence and mortality.

Genomic alterations associated with HER2+ breast cancer risk and clinical outcome in response to trastuzumab

Human epidermal growth factor receptor 2 positive (HER2+) breast cancer (BC) is an aggressive BC subtype characterized by HER2 overexpression/amplification. Genomic alterations of HER2 and others have been reported to be associated with, HER2 overexpression and prediction of trastuzumab-response. Here, we aimed at identifying germline and somatic alterations associated with HER2+ BC and evaluating their association with clinical outcome in response to trastuzumab therapy given to HER2+ BC patients. Global Sequencing Array (GSA) and polymerase chain reaction-restriction length polymorphism (PCR-RFLP) techniques were used to determine alterations in HER2 and other HER2-interacting as well as signaling-related genes in HER2+ BC. In addition, 20 formalin fixed paraffin-embedded tissue samples were also evaluated by GSA for identifying significant variations associated with HER + BC as well as response to trastuzumab therapy. A germline variant in HER2 (I655V) was found to be significantly associated with the risk of the disease (p < 0.01). A nonsense mutation in PTPN11 (K99X), a pathogenic CCND1 splice site variant (P241P), a hotspot missense mutation in PIK3CA (E542K) and a hotspot missense mutation in TP53 (R249S); were observed in 25%, 75%, 30% and 40% of the HER2+ BC tissue samples, respectively. Mutant CCND1 (P241P) and PIK3CA (E542K) were found to be significantly associated with reduced disease-free survival (DFS) in patients treated with trastuzumab (p: 0.018 and 0.005, respectively). These results indicate that HER2, PTPN11, CCND1 and PIK3CA genes are important biomarkers in HER2+ BC. Moreover, the patients harboring mutant CCND1 and PIK3CA exhibit a poorer clinical outcome as compared to those carrying wild-type CCND1 and PIK3CA.

Her2 Ile655Val polymorphism and its association with breast cancer risk: an updated meta-analysis of case-control studies

Breast cancer (BC) is one of the most common types of cancer in women worldwide. Several factors including genetic and environmental have been linked with susceptibility to development of BC. Her2 is a transmembrane protein with tyrosine kinase activity, overexpressed in several cancers including BC. Various studies in different populations have shown association of Her2 variants with susceptibility to BC, however these results were inconsistent, inconclusive and controversial. To obtain a common conclusive finding, we performed meta-analysis of 35 case-control studies reported earlier including 19, 220 cases and 22, 306 controls. We observed significant association of Her2^Ile655^Val polymorphism with susceptibility to development of breast cancer (Overall allele Val vs Ile: OR = 1.130, 95% CI = 1.051–1.216, p = 0.001; Ile-Val vs Ile-Ile: OR = 1.100, 95% CI = 1.016–1.192, p = 0.019; Val-Val+Ile-Val vs Ile-Ile: OR = 1.127, 95% CI = 1.038–1.223, p = 0.004). Subgroup analysis indicated a significant association with susceptibility to breast cancer in African and Asian populations. However, such association was not observed in other ethnic groups. Our findings suggested that Her2^Ile655^Val polymorphism is associated with breast cancer risk in overall, Asian and African populations, and can be used as diagnostic marker for BC.