CARF enrichment promotes epithelial\u2013mesenchymal transition via Wnt/\u03b2-catenin signaling: its clinical relevance and potential as a therapeutic target

Rajkumar S Kalra,A-Rum Yoon,Sukant Garg,Priyanshu Bhargava,Amr Omar,Chae-Ok Yun,Sunil C Kaul,Anupama Chaudhary,Renu Wadhwa

doi:10.1038/s41389-018-0048-4

CARF enrichment promotes epithelial\u2013mesenchymal transition via Wnt/\u03b2-catenin signaling: its clinical relevance and potential as a therapeutic target

Rajkumar S Kalra, A-Rum Yoon + Show 7 more

Open Access

https://doi.org/10.1038/s41389-018-0048-4

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Abstract

CARF (Collaborator of ARF)/CDKN2AIP was discovered as a novel ARF-binding protein. It has been established as an essential cell survival, p53-, and cell proliferation-regulatory protein. Although a moderate upregulation of CARF caused growth arrest and senescence, its excessively enriched levels were shown to facilitate aggressive proliferation and malignant transformation of cancer cells. Here, we examined the relevance of CARF levels in clinical tumors and found its amplification (both at gene and transcript levels) in a variety of invasive and metastatic malignancies. Consistent with the clinical readouts, enrichment of CARF in cancer cells promoted epithelial–mesenchymal transition (EMT). Cancer database and molecular analyses revealed that it activates Wnt/β-catenin signaling axis, as evident by enhanced nuclear localization and function of β-catenin marked by increased level of SNAIL1, SNAIL2, ZEB1, and TWIST1 and its downstream gene targets. Of note, targeted knockdown of CARF led to decrease in nuclear β-catenin and its key downstream effectors, involved in EMT progression. Consistent with this, CARF targeting in vivo either by naked siRNA or CARF shRNA harboring adeno-oncolytic virus caused suppression of tumor progression and lung metastasis. Taken together, we report clinical and therapeutic relevance of CARF in EMT and cancer invasiveness/metastasis, and propose it as a potent therapeutic target of aggressive cancers.

Highlights

Systematic diagnosis, screening, and targeted therapeutic approaches have considerably improved clinical response and survival of cancer patients in last decade
In order to further confirm CARF correlation with metastasis, we examined the status of 31 genes in NEPC (2016) dataset having patients with (n = 10) and without (n = 97) CARF amplification
CDH1, shown to decline during invasion or epithelial–mesenchymal transition (EMT) progression[20,21,22], showed the least change in CARF-amplified patients. These data strongly suggested that CARF amplification is associated with metastatic properties of the cancer cells

Summary

Introduction

Systematic diagnosis, screening, and targeted therapeutic approaches have considerably improved clinical response and survival of cancer patients in last decade. Transcription factors, viz. Slug, Snail, and Twist have been demonstrated to regulate this process and are in turn influenced by diverse signaling pathways including TGF-β1, RTK (Receptor Tyrosine Kinase) receptors, i.e., EGFR, ERBB2/HER2-AKT, ITGB1/FAK, NOTCH, and Wnt/β-catenin proteins[4,10]. Deregulated function of TGF-β1, a regulatory cytokine has been associated with tumor initiation and metastases[11]. It is frequently amplified in metastatic breast and pancreatic cancers[12] and found to promote malignant and metastatic characteristics via activation of Snail and Zeb[113]. The RTK receptors, EGFR and ERBB2 (frequently amplified in glioblastoma, breast and esophagus cancers) have been shown to promote EMT12

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