Cell Signalling by a Novel SH2 Domain Protein that is Overexpressed with Her2 in Breast Cancer

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.

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Secreted CXCL12 (SDF-1) forms dimers under physiological conditions

Biochemical Journal ◽

10.1042/bj20111341 ◽

2012 ◽

Vol 442 (2) ◽

pp. 433-442 ◽

Cited By ~ 35

Author(s):

Paramita Ray ◽

Sarah A. Lewin ◽

Laura Anne Mihalko ◽

Sasha-Cai Lesher-Perez ◽

Shuichi Takayama ◽

...

Keyword(s):

Breast Cancer ◽

Extracellular Space ◽

Mammalian Cells ◽

Cell Signalling ◽

Xenograft Model ◽

Physiological Conditions ◽

Cxc Chemokine ◽

Chemokine Ligand ◽

Chemokine Cxcl12 ◽

And Function

Chemokine CXCL12 (CXC chemokine ligand 12) signalling through CXCR (CXC chemokine receptor) 4 and CXCR7 has essential functions in development and underlies diseases including cancer, atherosclerosis and autoimmunity. Chemokines may form homodimers that regulate receptor binding and signalling, but previous studies with synthetic CXCL12 have produced conflicting evidence for homodimerization. We used bioluminescence imaging with GL (Gaussia luciferase) fusions to investigate dimerization of CXCL12 secreted from mammalian cells. Using column chromatography and GL complementation, we established that CXCL12 was secreted from mammalian cells as both monomers and dimers. Secreted CXCL12 also formed homodimers in the extracellular space. Monomeric CXCL12 preferentially activated CXCR4 signalling through Gαi and Akt, whereas dimeric CXCL12 more effectively promoted recruitment of β-arrestin 2 to CXCR4 and chemotaxis of CXCR4-expressing breast cancer cells. We also showed that CXCR7 preferentially sequestered monomeric CXCL12 from the extracellular space and had minimal effects on dimeric CXCL12 in cell-based assays and an orthotopic tumour xenograft model of human breast cancer. These studies establish that CXCL12 secreted from mammalian cells forms homodimers under physiological conditions. Since monomeric and dimeric CXCL12 have distinct effects on cell signalling and function, our results have important implications for ongoing efforts to target CXCL12 pathways for therapy.

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Methyl-CpG binding domain protein 2 plays a causal role in breast cancer growth and metastasis

10.1101/2020.10.06.328989 ◽

2020 ◽

Author(s):

Niaz Mahmood ◽

Ani Arakelian ◽

Moshe Szyf ◽

Shafaat A. Rabbani

Keyword(s):

Breast Cancer ◽

Dna Methylation ◽

Mammary Tumor ◽

Tumor Burden ◽

Tumor Formation ◽

Binding Domain ◽

Causal Role ◽

Molecular Signaling ◽

Primary Tumors ◽

Domain Protein

AbstractMethyl-CpG-binding domain protein 2 (Mbd2), a reader of DNA-methylation, has been implicated in the progression of several types of malignancies, including breast cancer. To test whether Mbd2, which is overexpressed in human breast cancer samples and in MMTV-PyMT mammary pads, plays a causal role in mammary tumor growth and metastasis we depleted Mbd2 in transgenic MMTV-PyMT model of breast cancer by cross-breeding with Mbd2 knockout mice to generate heterozygous (PyMT;Mbd2+/-) and homozygous (PyMT;Mbd2-/-) animals. We found that Mbd2 depletion caused a gene dose-dependent delay in mammary tumor formation, reduced primary tumor burden, and lung metastasis at the experimental endpoint. In addition, animals from the PyMT;Mbd2-/- group survived significantly longer compared to the wildtype (PyMT;Mbd2+/+) and PyMT;Mbd2+/- arms. Transcriptomic and proteomic analyses of the primary tumors obtained from PyMT;Mbd2+/+ and PyMT;Mbd2+/- groups revealed that Mbd2 depletion alters several key determinants of the molecular signaling networks related to tumorigenesis and metastasis, which thereby demonstrate that Mbd2 is regulating transcriptional programs critical for breast cancer. To our knowledge, this is the first study demonstrating a causal role for a DNA-methylation reader in breast cancer. Results from this study will provide the rationale for further development of first-in-class targeted epigenetic therapies against Mbd2 to inhibit the progression of breast and other common cancers.

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Triple Negative Breast Cancer: A review of common therapeutic Targets and Current Treatment options.

University of Ottawa Journal of Medicine ◽

10.18192/uojm.v7i1.1563 ◽

2017 ◽

Vol 7 (1) ◽

Author(s):

Daud Akhtar ◽

Ahsen Chaudhry

Keyword(s):

Breast Cancer ◽

Overall Survival ◽

Side Effects ◽

Triple Negative Breast Cancer ◽

Cancer Du Sein ◽

Triple Negative ◽

Treatment Options ◽

Cell Signalling ◽

Effets Secondaires ◽

Breast Cancer Chemotherapy

Triple negative breast cancer (TNBC) is a subtype of breast cancer which lacks ER, PR, and HER2 expression. It is characterized by poor prognosis and resistance to standard treatment forms for breast cancer. Chemotherapy is still currently the core neo-adjuvant treatment option for patients with TNBC, although it has mixed levels of efficacy on overall survival and many serious side effects. Platinum- based therapies have been used to treat TNBC in conjunction with chemotherapy, but they are not a widely effective treatment due to the heterogeneity of TNBC. For this reason, other novel approaches, particularly those which target molecular components involved in TNBC pathogenesis, are being investigated. Angiogenesis inhibitors, which include monoclonal antibodies or small molecules that inhibit VEGF, have been shown to improve progression-free survival, but have not demonstrated an impact on overall survival. PARP enzyme inhibitors, when combined with chemotherapy and carboplatin for the treatment of TNBC, have demonstrated a significant reduction in risk progression and mortality. However, the majority of PARP inhibitors are still in trials and their effectiveness in clini- cal settings has yet to be determined. Additional proposed targets for directed therapy against TNBC include cell signalling pathways involving EGFR or PI3K. Overall, issues such as treatment resistance and side effects are important challenges that must be overcome in order to enable improvements in patient prognosis and clinical impact. RÉSUMÉ Le cancer du sein triple négatif (CSTN) est un sous-type de cancer du sein auquel il manque les récepteurs d’œstrogènes (ER), les récepteurs de progestérone (PR) et l’expression de HER2. Il est caractérisé par un pronostic défavorable et une résistance aux traite- ments standards du cancer du sein. À l’heure actuelle, la chimiothérapie est encore l’option principale de traitement néoadjuvant pour les patients ayant le CSTN, bien qu’elle ait des niveaux variés d’efficacité sur la survie globale, ainsi que de nombreux effets secondaires sérieux. Les thérapies à base de platine ont été utilisées pour traiter le CSTN en conjonction avec la chimiothérapie, mais elles ne sont pas très efficaces étant donné l’hétérogénéité du CSTN. En raison de cela, d’autres approches novatrices, particulièrement celles qui ciblent les composantes moléculaires impliquées dans la pathogenèse du CSTN, font actuellement l’objet d’enquêtes. Les inhibiteurs de l’angiogenèse, dont les anticorps monoclonaux ou les petites molécules inhibant le VEGF, ont démontré la capacité d’améliorer la survie sans progression de la maladie, mais n’ont pas démontré d’impact sur la survie globale. Les inhibiteurs d’enzymes PARP, lorsque combinés avec la chimiothérapie et le carboplatine pour le traitement du CSTN, ont démontré une réduction significative du risque de progression et de la mortalité. Toutefois, la majorité des inhibiteurs PARP subissent encore des essais et leur efficacité clinique reste à être déterminée. D’autres cibles suggérées pour la thérapie dirigée contre le CSTN incluent les voies de signalisation impliquant le EGFR ou le PI3K. Dans l’ensemble, des problèmes tels la résistance au traitement et les effets secondaires sont des défis importants qui doivent être surmontés afin de permettre des améliorations au niveau du pronostic du patient et de l’impact clinique.

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Probing factors affecting the gas phase stabilities of noncovalent complexes formed by peptides bound to the Grb2 SH2 domain protein

Physical Chemistry Chemical Physics ◽

10.1039/b315435a ◽

2004 ◽

Vol 6 (10) ◽

pp. 2572 ◽

Cited By ~ 9

Author(s):

M. Isabel Catalina ◽

Nico J. de Mol ◽

Marcel J. E. Fischer ◽

Albert J. R. Heck

Keyword(s):

Gas Phase ◽

Sh2 Domain ◽

Noncovalent Complexes ◽

Factors Affecting ◽

Domain Protein

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