CD47-SIRPα Signaling Induces Epithelial-Mesenchymal Transition and Cancer Stemness and Links to a Poor Prognosis in Patients with Oral Squamous Cell Carcinoma.

Shin Pai,Ming-Hsien Chien,Chun-Shu Lin,Pei-Yi Chu,Jo-Ting Tsai,Oluwaseun Adebayo Bamodu,Yen-Kuang Lin,Chi-Tai Yeh,Liang-Shun Wang,Michael Hsiao

doi:10.3390/cells8121658

Abstract

Background: Oral squamous cell carcinoma (OSCC), with high mortality rates, is one of the most diagnosed head and neck cancers. Epithelial-to-mesenchymal transition (EMT) and the generation of cancer stem cells (CSCs) are two keys for therapy-resistance, relapse, and distant metastasis. Accumulating evidence indicates that aberrantly expressed cluster of differentiation (CD)47 is associated with cell-death evasion and metastasis; however, the role of CD47 in the generation of CSCs in OSCC is not clear. Methods: We investigated the functional roles of CD47 in OSCC cell lines SAS, TW2.6, HSC-3, and FaDu using the bioinformatics approach, immunoblotting, immunofluorescence staining, and assays for cellular migration, invasion, colony, and orosphere formation, as well as radiosensitivity. Results: We demonstrated increased expression of CD47 in OSCC patients was associated with an estimated poorly survival disadvantage (p = 0.0391) and positively correlated with the expression of pluripotency factors. Silencing CD47 significantly suppressed cell viability and orosphere formation, accompanied by a downregulated expression of CD133, SRY-Box transcription factor 2 (SOX2), octamer-binding transcription factor 4 (OCT4), and c-Myc. In addition, CD47-silenced OSCC cells showed reduced EMT, migration, and clonogenicity reflected by increased E-cadherin and decreased vimentin, Slug, Snail, and N-cadherin expression. Conclusion: Of therapeutic relevance, CD47 knockdown enhanced the anti-OSCC effect of radiotherapy. Collectively, we showed an increased CD47 expression promoted the generation of CSCs and malignant OSCC phenotypes. Silencing CD47, in combination with radiation, could provide an alternative and improved therapeutic efficacy for OSCC patients.

Highlights

Oral cancer is one of the most diagnosed malignancies, with a global annual incidence of 300,373 cases [1]
To understand the role of CD47 in Oral squamous cell carcinoma (OSCC), we performed computational analyses of CD47 RNAseq expression profile in 33 different cancer types (n = 9736 tumors), including head and neck squamous cell carcinoma (HNSCC) matched with corresponding normal samples from the cancer genome atlas (TCGA) and genotype-tissue expression (GTEx) (n = 8587 non-tumors) datasets, using the analysis of variance for the evaluation of differential expression. Results of these analyses indicated that CD47 was overexpressed in tumors compared to adjacent non-tumor oral tissues and was mostly expressed in HNSCC tissues with ~ 125 transcripts per million (TPM) after the ovarian (OV, ~198 TPM) and lung adenocarcinoma (LUAD, ~195 TPM) (Figure 1A and Supplementary Figure S1)
Despite advances made in the diagnostic approach and therapeutic strategies, OSCC remains a Despite advances the diagnostic approach and therapeutic strategies, remains a clinical challenge withmade great in financial and emotional implications for patients andOSCC

Summary

Introduction

Oral cancer is one of the most diagnosed malignancies, with a global annual incidence of 300,373 cases [1]. Constituting over 90% of all oral cancer histological subtypes, the oral squamous cell carcinoma (OSCC) is notably highly aggressive, often non-responsive to common anticancer therapy, and associated with early relapse and poor prognosis [1,2]. Despite the documented therapeutic relevance of radiotherapy for the reduction of OSCC tumor size and oral function preservation, it is common for irradiated OSCC patients to develop early loco-regional disease relapse, further contributing to the dismal prognosis [5]. Putting together, these inform the need for the discovery of novel actionable molecular target or development of novel therapeutic agents with better efficacy. Silencing CD47 significantly suppressed cell viability and orosphere formation, accompanied by a downregulated expression of CD133, SRY-Box transcription factor 2 (SOX2), octamer-binding transcription factor 4 (OCT4), and c-Myc

Methods

Results

Conclusion