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Taye N, Alam A, Ghorai S, Chatterji DG, Parulekar A, Mogare D, Singh S, Sengupta P, Chatterjee S, Bhat MK, Santra MK, Salunkhe PB, Finston SK, Chattopadhyay S. SMAR1 inhibits Wnt/β-catenin signaling and prevents colorectal cancer progression. Oncotarget 2018; 9:21322-21336. [PMID: 29765542 PMCID: PMC5940383 DOI: 10.18632/oncotarget.25093] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 03/21/2018] [Indexed: 12/13/2022] Open
Abstract
Reduced expression of Scaffold/Matrix Attachment Region Binding Protein 1 (SMAR1) is associated with various cancers resulting in poor prognosis of the diseases. However, the precise underlying mechanism elucidating the loss of SMAR1 requires ongoing study. Here, we show that SMAR1 is highly downregulated during aberrant Wnt3a signaling due to proteasomal degradation and predicted poor prognosis of colorectal cancer. However, substitution mutation (Arginine and Lysine to Alanine) in the D-box elements of SMAR1 viz. "RCHL" and "RQRL" completely abrogated its proteasomal degradation despite Wnt3a activity. SMAR1 inhibited Wnt/β-catenin signaling by recruiting Histone deacetylase-5 to β-catenin promoter resulting in reduced cell migration and invasion. Consequently, reduced tumor sizes in in-vivo NOD-SCID mice were observed that strongly associated with suppression of β-catenin. However, loss of SMAR1 led to enriched H3K9 Acetylation in the β-catenin promoter that further increased Wnt/β-catenin signaling activities and enhanced colorectal cancer progression drastically. Using docking and isothermal titration calorimetric studies we show that small microbial peptides viz. AT-01C and AT-01D derived from Mycobacterium tuberculosis mask the D-box elements of SMAR1. These peptides stabilized SMAR1 expression that further inhibited metastatic SW480 colorectal cancer cell migration and invasion. Drastically reduced subcutaneous tumors were observed in in-vivo NOD-SCID mice upon administration of these peptides (25 mg/kg body weight) intraperitoneally. Taken together our structural studies, in-vitro and in-vivo results strongly suggest that the D-box elements of SMAR1 represent novel druggable targets, where the microbial peptides hold promise as novel colorectal cancer therapeutics.
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Affiliation(s)
- Nandaraj Taye
- National Centre for Cell Science, Pune 411 007, India
| | - Aftab Alam
- National Centre for Cell Science, Pune 411 007, India
| | | | | | | | - Devraj Mogare
- National Centre for Cell Science, Pune 411 007, India
| | | | - Pallabi Sengupta
- Department of Biophysics, Bose Institute, Kolkata 700 054, India
| | | | | | | | | | | | - Samit Chattopadhyay
- National Centre for Cell Science, Pune 411 007, India
- Indian Institute of Chemical Biology (CSIR), West Bengal, Kolkata 700 032, India
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