Presentation Authors: Cheng Liu*, Min Qiu, Runzhuo Ma, Lulin Ma, Beijing, China, People's Republic of
Introduction: The critical role of epidermal growth factor receptor (EGFR) signaling pathway in the pathogenesis and progression of renal cell carcinoma (RCC) has been well established. However, few studies have addressed the regulation of EGFR expression in RCC cells. SET and MYND domain-containing protein 3 (SMYD3) is a histone methyltransferase and plays an important role in gene transcription and oncogenesis. The expression and function of SMYD3 in RCC remains unclear.
Methods: We analyzed SMYD3 expression in human RCC with Western blot and immunohistochemistry. SMYD3 expression was knocked down using short hairpin RNAs (shRNA). Cell proliferation, colony formation, apoptosis analyses and xenograft transplantation were performed to evaluate the impact of SMYD3 depletion on RCC cells. EGFR expression and promoter activity were determined using qPCR, western blot, and luciferase reporter assay. EGFR promoter association with Sp1, SMYD3, and histone modifications was assessed by chromatin immunoprecipitation.
Results: We identified that SMYD3 promoted RCC development through directly activating EGFR at transcriptional level. We found that SMYD3 expression was elevated in RCC tissues and associated with tumor stage, histological grade, nuclear grade and oncological outcome. Depletion of SMYD3 inhibited RCC cell proliferation, colony formation, and xenograft tumor formation, and led cell apoptosis. Two functional SMYD3-binding motifs were identified in the EGFR promoter region. In addition, we validated the accumulation of SMYD3 and SP1 at the EGFR promoter binding site, thereby increasing the transcriptional activity of EGFR promoter through chromatin remodeling in RCC cells.
Conclusions: SMYD3 as a poor prognostic indicator promotes RCC malignant progression via direct activation of EGFR transcription and expression.