Epigenetically regulated Fibronectin leucine rich transmembrane protein 2 (FLRT2) shows tumor suppressor activity in breast cancer cells

Beclin 1, an autophagy and haploinsufficient tumor-suppressor protein, is frequently monoallelically deleted in breast and ovarian cancers. However, the precise mechanisms by which Beclin 1 inhibits tumor growth remain largely unknown. To address this question, we performed a genome-wide CRISPR/Cas9 screen in MCF7 breast cancer cells to identify genes whose loss of function reverse Beclin 1-dependent inhibition of cellular proliferation. Small guide RNAs targeting CDH1 and CTNNA1, tumor-suppressor genes that encode cadherin/catenin complex members E-cadherin and alpha-catenin, respectively, were highly enriched in the screen. CRISPR/Cas9-mediated knockout of CDH1 or CTNNA1 reversed Beclin 1-dependent suppression of breast cancer cell proliferation and anchorage-independent growth. Moreover, deletion of CDH1 or CTNNA1 inhibited the tumor-suppressor effects of Beclin 1 in breast cancer xenografts. Enforced Beclin 1 expression in MCF7 cells and tumor xenografts increased cell surface localization of E-cadherin and decreased expression of mesenchymal markers and beta-catenin/Wnt target genes. Furthermore, CRISPR/Cas9-mediated knockout of BECN1 and the autophagy class III phosphatidylinositol kinase complex 2 (PI3KC3-C2) gene, UVRAG, but not PI3KC3-C1–specific ATG14 or other autophagy genes ATG13, ATG5, or ATG7, resulted in decreased E-cadherin plasma membrane and increased cytoplasmic E-cadherin localization. Taken together, these data reveal previously unrecognized cooperation between Beclin 1 and E-cadherin–mediated tumor suppression in breast cancer cells.

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Induction of PDCD4 tumor suppressor gene expression by RAR agonists, antiestrogen and HER-2/neu antagonist in breast cancer cells. Evidence for a role in apoptosis

Oncogene ◽

10.1038/sj.onc.1207983 ◽

2004 ◽

Vol 23 (49) ◽

pp. 8135-8145 ◽

Cited By ~ 98

Author(s):

Olubunmi Afonja ◽

Dominique Juste ◽

Sharmistha Das ◽

Sachiko Matsuhashi ◽

Herbert H Samuels

Keyword(s):

Breast Cancer ◽

Gene Expression ◽

Tumor Suppressor ◽

Cancer Cells ◽

Tumor Suppressor Gene ◽

Breast Cancer Cells ◽

Suppressor Gene ◽

Her 2

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Mortaparib, a novel dual inhibitor of mortalin and PARP1, is a potential drug candidate for ovarian and cervical cancers

Journal of Experimental & Clinical Cancer Research ◽

10.1186/s13046-019-1500-9 ◽

2019 ◽

Vol 38 (1) ◽

Cited By ~ 1

Author(s):

Jayarani F. Putri ◽

Priyanshu Bhargava ◽

Jaspreet Kaur Dhanjal ◽

Tomoko Yaguchi ◽

Durai Sundar ◽

...

Keyword(s):

Tumor Suppressor ◽

Cancer Cells ◽

Cancer Cell ◽

Growth Arrest ◽

Suppressor Activity ◽

Dual Inhibitor ◽

Tumor Suppressor Activity ◽

And Migration

Abstract Background Mortalin is enriched in a large variety of cancers and has been shown to contribute to proliferation and migration of cancer cells in multiple ways. It has been shown to bind to p53 protein in cell cytoplasm and nucleus causing inactivation of its tumor suppressor activity in cancer cells. Several other activities of mortalin including mitochondrial biogenesis, ATP production, chaperoning, anti-apoptosis contribute to pro-proliferative and migration characteristics of cancer cells. Mortalin-compromised cancer cells have been shown to undergo apoptosis in in vitro and in vivo implying that it could be a potential target for cancer therapy. Methods We implemented a screening of a chemical library for compounds with potential to abrogate cancer cell specific mortalin-p53 interactions, and identified a new compound (named it as Mortaparib) that caused nuclear enrichment of p53 and shift in mortalin from perinuclear (typical of cancer cells) to pancytoplasmic (typical of normal cells). Biochemical and molecular assays were used to demonstrate the effect of Mortaparib on mortalin, p53 and PARP1 activities. Results Molecular homology search revealed that Mortaparib is a novel compound that showed strong cytotoxicity to ovarian, cervical and breast cancer cells. Bioinformatics analysis revealed that although Mortaparib could interact with mortalin, its binding with p53 interaction site was not stable. Instead, it caused transcriptional repression of mortalin leading to activation of p53 and growth arrest/apoptosis of cancer cells. By extensive computational and experimental analyses, we demonstrate that Mortaparib is a dual inhibitor of mortalin and PARP1. It targets mortalin, PARP1 and mortalin-PARP1 interactions leading to inactivation of PARP1 that triggers growth arrest/apoptosis signaling. Consistent with the role of mortalin and PARP1 in cancer cell migration, metastasis and angiogenesis, Mortaparib-treated cells showed inhibition of these phenotypes. In vivo tumor suppression assays showed that Mortaparib is a potent tumor suppressor small molecule and awaits clinical trials. Conclusion These findings report (i) the discovery of Mortaparib as a first dual inhibitor of mortalin and PARP1 (both frequently enriched in cancers), (ii) its molecular mechanism of action, and (iii) in vitro and in vivo tumor suppressor activity that emphasize its potential as an anticancer drug.

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