Effects on human transcriptome of mutated BRCA1 BRCT domain: A microarray study

Abstract

BackgroundBRCA1 (breast cancer 1, early onset) missense mutations have been detected in familial breast and ovarian cancers, but the role of these variants in cancer predisposition is often difficult to ascertain. In this work, the molecular mechanisms affected in human cells by two BRCA1 missense variants, M1775R and A1789T, both located in the second BRCT (BRCA1 C Terminus) domain, have been investigated. Both these variants were isolated from familial breast cancer patients and the study of their effect on yeast cell transcriptome has previously provided interesting clues to their possible role in the pathogenesis of breast cancer.MethodsWe compared by Human Whole Genome Microarrays the expression profiles of HeLa cells transfected with one or the other variant and HeLa cells transfected with BRCA1 wild-type. Microarray data analysis was performed by three comparisons: M1775R versus wild-type (M1775RvsWT-contrast), A1789T versus wild-type (A1789TvsWT-contrast) and the mutated BRCT domain versus wild-type (MutvsWT-contrast), considering the two variants as a single mutation of BRCT domain.Results201 differentially expressed genes were found in M1775RvsWT-contrast, 313 in A1789TvsWT-contrast and 173 in MutvsWT-contrast. Most of these genes mapped in pathways deregulated in cancer, such as cell cycle progression and DNA damage response and repair.ConclusionsOur results represent the first molecular evidence of the pathogenetic role of M1775R, already proposed by functional studies, and give support to a similar role for A1789T that we first hypothesized based on the yeast cell experiments. This is in line with the very recently suggested role of BRCT domain as the main effector of BRCA1 tumor suppressor activity.

Pathogenicity of Mutations Discovered in BRCA1 BRCT Domains is Characterized by Destabilizing the Hydrophobic Interactions

“…We can also conclude that hydrophobic interactions play a very important role in unraveling the functional complexities of BRCA1 BRCT mutations. Structural folding, weak intermolecular interactions and microarray analysis have already been reported for the pathogenic mutations M1775R [46] and M1775K [47], and to our conclusion we have found these mutations are not only impairing transactivation function but also destabilizing the hydrophobic interactions of BRCA1 BRCT.…”

Dual Mechanisms of LYN Kinase Dysregulation Drive Aggressive Behavior in Breast Cancer Cells

“…Therefore, mutation of the N-terminal RING domain (which disrupts binding to BARD1) does not alter the ability of BRCA1 to suppress the PIN1–LYN activation pathway. In contrast, mutation of the coiled-coil domain, affecting PALB2 binding (suggested to be critical for the activation of the BRCA1 transcriptional program as well as for DNA repair) (Anantha et al, 2017; Gardini et al, 2014) and of the C-terminal BRCT domains, important for interactions with Abraxas, BRIP1 and CtIP (Anantha et al, 2017) and known to be important for BRCA1 transcriptional activity (Hayes et al, 2000; Iofrida et al, 2012), do result in elevated levels of PIN1 and LYN activation. These support a model in which the transcriptional activity of BRCA1 is critical in the control of PIN1–LYN pathway activation.…”

Interferon-γ signaling is associated with BRCA1 loss-of-function mutations in high grade serous ovarian cancer

“…10,11 Tumor-associated BRCA1 mutations commonly affecting the BRCT domain confer increased sensitivity to DNA damaging agents and to poly ADP ribose polymerase (PARP) inhibitors and are associated with substantial transcriptional rewiring in cancer cells and tumors. 12–15…”