The Relevance of the SH2 Domain for c-Src Functionality in Triple-Negative Breast Cancer Cells

Abstract

The role of Src family kinases (SFKs) in human tumors has been always associated with tyrosine kinase activity and much less attention has been given to the SH2 and SH3 adapter domains. Here, we studied the role of the c-Src-SH2 domain in triple-negative breast cancer (TNBC). To this end, SUM159PT and MDA-MB-231 human cell lines were employed as model systems. These cells conditionally expressed, under tetracycline control (Tet-On system), a c-Src variant with point-inactivating mutation of the SH2 adapter domain (R175L). The expression of this mutant reduced the self-renewal capability of the enriched population of breast cancer stem cells (BCSCs), demonstrating the importance of the SH2 adapter domain of c-Src in the mammary gland carcinogenesis. In addition, the analysis of anchorage-independent growth, proliferation, migration, and invasiveness, all processes associated with tumorigenesis, showed that the SH2 domain of c-Src plays a very relevant role in their regulation. Furthermore, the transfection of two different aptamers directed to SH2-c-Src in both SUM159PT and MDA-MB-231 cells induced inhibition of their proliferation, migration, and invasiveness, strengthening the hypothesis that this domain is highly involved in TNBC tumorigenesis. Therefore, the SH2 domain of c-Src could be a promising therapeutic target and combined treatments with inhibitors of c-Src kinase enzymatic activity may represent a new therapeutic strategy for patients with TNBC, whose prognosis is currently very negative.

Selective and Potent PROTAC Degraders of c-Src Kinase

“…12 In TNBC, c-Src's SH2 domain has been shown to be important for tumorigenicity. 14 PROTACs provide a means of chemical knockdown 15 that will prevent both catalytic and noncatalytic functions, and we were thus interested in developing a PROTAC for c-Src.…”

“…Upon knockdown (e.g., with siRNA), triple-negative breast cancer (TNBC) and basal bladder cancers exhibit decreased proliferation and invasion properties. , Unfortunately, studies with small-molecule inhibitors of c-Src (including: dasatinib, bosutinib, and ponatinib) failed to recapitulate the strong anticancer phenotype observed from genetic knockdown of c-Src and were not successful in the clinic. , Many noncatalytic functions have been reported for c-Src, typically involving protein–protein interaction between a partner protein and c-Src’s SH2 and SH3 domains. , Several binding partners of c-Src have been identified, including epidermal growth factor receptors, focal adhesion kinase, and hormone receptors . In TNBC, c-Src’s SH2 domain has been shown to be important for tumorigenicity . PROTACs provide a means of chemical knockdown that will prevent both catalytic and noncatalytic functions, and we were thus interested in developing a PROTAC for c-Src.…”

Tumor Cell‐Intrinsic CD96 Mediates Chemoresistance and Cancer Stemness by Regulating Mitochondrial Fatty Acid β‐Oxidation

“…[16,18,39] YXXM interacts with signal transduction proteins containing the SH2 domain, [11,16] which is crucial for the stemness of CSCs. [40,41] Based on this information, we asked whether the CD96 YXXM motif is responsible for BCSCs regulation. We first examined the expression and phosphorylation of a series of SH2-containing proteins known to participate in CSCs regulation.…”

Endogenous and Exogenous Regulatory Signaling in the Secretory Pathway: Role of Golgi Signaling Molecules in Cancer

“…The Src family kinases (SFKs) are a family of non-receptor tyrosine kinases responsible for signal transduction during many cellular events, such as differentiation, adhesion, and migration. This family is composed of nine members, whose distinguish feature is a modular structure containing the Src homology domains 2 and 3 (SH2 and SH3), which are involved in protein-protein interactions ( Espada and Martin-Perez, 2017 ; Shah et al, 2018 ; Mayoral-Varo et al, 2021 ). Altered Src activity is associated with enhanced tumor progression, and several mechanisms have been proposed to explain it.…”