RUNX2 and WWOX genes as molecular biomarkers and candidates for targeted therapy in Egyptian patients with primary conventional osteosarcoma

Abeer A Bahnassy,Eman Abdelzaher,Awad Abdel Moniem A Rafalla,Layla Kamal Younis,Gamal Elhosseiny,Abdel-Rahman N Zekri,Ahmad El-Bastawisi,Hend F Yousif,Rania Gaber

doi:10.1186/s41241-016-0001-9

Abstract

The conventional osteosarcoma (OS) is the commonest primary malignant, bone tumor with complex genomic profiles and poor survival. Runt-related transcription factor 2 (RUNX2) and WW domain containing oxidoreductase (WWOX) genes are implicated in normal osteogenesis as well as in the development of primary conventional OS. We retrospectively assessed protein and RNA expression of the RUNX2 and WWOX genes by quantitative real time PCR (qPCR) and immunohistochemistry (IHC) in 80 cases of primary OS and 20 normal control (NC) subjects. Proteins and RNA expression levels of both genes were correlated to clinico-pathological features of the patients, progression free and overall survival (PFS& OS) rates. In OS, RUNX2 protein was detected in 72/80 (90%) cases compared to 4/20 (20%) NC samples (p. < 0.001) and RUNX2-RNA was up regulated (up to 103.2 folds) in 60/80 (75%) (p = 0.01). WWOX protein and RNA (up to 7.2 folds) were detected in all NC samples but in 24/80 (30%) and 20/80 (20%) OS cases; respectively (p. < 0.001 for each). The concordance between the RNA and protein expressions for RUNX2 and WWOX was significantly high (X_trend^2 = 6.33; p = 0.012 and X_trend^2 = 19, p < 0.001; respectively). A significant inverse relation existed between RUNX2 and WWOX RNA and protein (p = 0.032, p = 0.008). There was significant correlation between RUNX2 RNA/protein, high tumor grade and stage (p = <0.001; each); RUNX2 RNA and male gender, tumor site and metastasis (p = 0.007, 0.041, 0.003; respectively). WWOX protein associated significantly with advanced stage and metastasis (p = 0.001& 0.024; respectively) and WWOX RNA associated with metastasis (p = 0.003). RUNX2 and WWOX play opposing roles in the development and progression of OS. They could be used as sensitive prognostic biomarkers for OS patients and RUNX2 represents a promising candidate for targeted therapy.

Highlights

The conventional osteosarcoma (OS) is the commonest primary malignant, bone tumor with complex genomic profiles and poor survival
In the OS group, 72 (90%) out of the 80 cases assessed were positive for RUNX2 protein overexpression with a median staining score of 13 (Min.-Max. = 0–15, 95% CI = 53.3, 100) compared to 4/20 cases only (20%) for the control group with a median staining score of 5 (Min.-Max. = 0–8)
WW domain containing oxidoreductase (WWOX) protein expression was detected in all the control samples (100%; 95% CI = 0, 100) with a median staining score of 7 (Min.-Max. = 4–10) but in 24/80 (30%) OS cases only

Summary

Introduction

The conventional osteosarcoma (OS) is the commonest primary malignant, bone tumor with complex genomic profiles and poor survival. Osteosarcoma (OS) is the most common primary malignant, non-hematopoietic, bone tumor worldwide. According to the National Cancer Institute Registry in Egypt, OS represents the most common primary malignant bone tumor in constituting 47.75%, of the cases followed by Ewing’s sarcoma (17.57%), chondrosarcoma (14.86%) and NonHodgkin lymphoma (9.01%) (NCI) [3]. It is one of the significant causes of morbidity and mortality, especially in the young age group [1]. Studying the molecular pathogenesis of OS is highly required for better understanding of tumor biology, to identify molecular prognostic and predictive biomarkers as well as for better selection of genes that could be used as candidates for targeted therapy [6, 7]

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Discussion

Conclusion