The Epigenetic Regulation of SOX9 by miR‐145 in Human Chondrosarcoma

Abstract

Chondrosarcoma is the most common primary bone malignancy in the adult population with a high rate of pulmonary metastasis. Chondrosarcoma is managed with surgical excision as the tumors do not respond well to conventional chemotherapy or radiation therapy. Thus, there exists a dire need to develop systemic treatment options to target chondrosarcoma cells for metastatic spread. We hypothesized that the expression of miR-145 is low in chondrosarcoma, leading to decreased transcriptional control of SOX9 (the master regulator of chondrogenesis), and downstream activation of the transcription factor ETV5. We have previously shown that ETV5 activates MMP-2 expression in chondrosarcoma, which in turn increases local bone matrix resorption. In this study, we confirm high expression of SOX9 in human chondrosarcoma using real-time PCR, Western blotting, and immunofluorescence. An ETV5 promoter-reporter plasmid was transfected into chondrosarcoma cells to determine if SOX9 directly regulates the expression of ETV5. Co-transfection of the ETV5 promoter-plasmid with SOX9 lentivirus significantly increased the luciferase activity derived from the ETV5 promoter, from which the regulatory relationship between SOX9 and ETV5 is established. MiR-145 was found to be down-regulated in chondrosarcoma cell lines, patient samples, and further confirmed with a public sarcoma database. After stable miR-145 lentiviral transfection, the subsequent mRNA expression levels of SOX9, ETV5, and MMP-2 were significantly decreased in chondrosarcoma cells. The results generated by this study may have important clinical significance in the treatment of patients with chondrosarcoma in that targeted miRNA may have the potential to downregulate the upstream activators of proteases such as MMP-2.

The Osteological Paradox 20 Years Later: Past Perspectives, Future Directions

“…Research on aging and longevity (Calvanese et al 2009;Huidobro et al 2013;Slagboom et al 2011) and bone homeostatic disruptions (Gordon et al 2014;Vrtačnik et al 2014) are more relevant to bioarchaeology and discussions of the Osteological Paradox. For example, epigenetic research on osteoporosis and osteoarthritis (Barter and Young 2013;Delgado-Calle et al 2013;Iliopoulos et al 2008;Soto-Hermida et al 2014), rheumatoid arthritis (Liu et al 2013;Zufferey et al 2014), and malignant bone cancers such as multiple myeloma (Chim et al 2004;Chim et al 2007), chondrosarcoma (Fitzgerald et al 2011;Mak et al 2015), and Ewing's sarcoma (Alholle et al 2013;Patel et al 2012; see also Mundy 2002;Wise et al 2015) may help explain some aspects of health and stress conditions in the past. Research demonstrating a relationship between diet and different mechanisms of the epigenome (Burdge and Lillycrop 2010;Zhang et al 2011) also help contextualize the well-documented synergy between dietary foci and health experiences in past populations.…”

miR-124 inhibits cell proliferation, migration and invasion by directly targeting SOX9 in lung adenocarcinoma

“…Therefore, SOX9 may function as an oncogene or tumor suppressor depending on tumor origin. Intriguingly, several miRs, including miR-145 (24), miR-32 (25) and miR-101 (26), have been found to target SOX9 in different tissues. Real et al (27) showed that miR-124 can regulate the expression of SOX9 in developing mouse ovarian cells.…”

Aberrant DNA Methylations in Chondrosarcoma

“…For example, miRNA-145 is involved in chondrogenic differentiation through downregulating the expression of Sox9. The observed overexpression of Sox9 in CS implies the declining expression of miRNA-145 [43]. MiRNA-494, which inhibits cell proliferation and invasion of CS, was reported to be downregulated in CS tissues and human CS cell line SW1353 [42].…”