Impact of c-MYC expression on proliferation, differentiation, and risk of neoplastic transformation of human mesenchymal stromal cells

Abstract

Background: Mesenchymal stromal cells isolated from bone marrow (MSC) represent an attractive source of adult stem cells for regenerative medicine. However, thorough research is required into their clinical application safety issues concerning a risk of potential neoplastic degeneration in a process of MSC propagation in cell culture for therapeutic applications. Expansion protocols could preselect MSC with elevated levels of growth-promoting transcription factors with oncogenic potential, such as c-MYC. We addressed the question whether c-MYC expression affects the growth and differentiation potential of human MSC upon extensive passaging in cell culture and assessed a risk of tumorigenic transformation caused by MSC overexpressing c-MYC in vivo. Methods: MSC were subjected to retroviral transduction to induce expression of c-MYC, or GFP, as a control. Cells were expanded, and effects of c-MYC overexpression on osteogenesis, adipogenesis, and chondrogenesis were monitored. Ectopic bone formation properties were tested in SCID mice. A potential risk of tumorigenesis imposed by MSC with c-MYC overexpression was evaluated. Results: C-MYC levels accumulated during ex vivo passaging, and overexpression enabled the transformed MSC to significantly overgrow competing control cells in culture. C-MYC-MSC acquired enhanced biological functions of c-MYC: its increased DNA-binding activity, elevated expression of the c-MYC-binding partner MAX, and induction of antagonists P19ARF/P16INK4A. Overexpression of c-MYC stimulated MSC proliferation and reduced osteogenic, adipogenic, and chondrogenic differentiation. Surprisingly, c-MYC overexpression also caused an increased COL10A1/COL2A1 expression ratio upon chondrogenesis, suggesting a role in hypertrophic degeneration. However, the in vivo ectopic bone formation ability of c-MYC-transduced MSC remained comparable to control GFP-MSC. There was no indication of tumor growth in any tissue after transplantation of c-MYC-MSC in mice. Conclusions: C-MYC expression promoted high proliferation rates of MSC, attenuated but not abrogated their differentiation capacity, and did not immediately lead to tumor formation in the tested in vivo mouse model. However, upregulation of MYC antagonists P19ARF/P16INK4A promoting apoptosis and senescence, as well as an observed shift towards a hypertrophic collagen phenotype and cartilage degeneration, point to lack of safety for clinical application of MSC that were manipulated to overexpress c-MYC for their better expansion.

Mitochondria transfer enhances proliferation, migration, and osteogenic differentiation of bone marrow mesenchymal stem cell and promotes bone defect healing

“…C-Myc is an oncogene involved in orchestrating changes in cell metabolism necessary for cellcycle entry in mitotic cells [18]. Since c-Myc expression has been proven to promote proliferation rates of MSC in previous studies [19,20], we evaluated the mRNA and protein expression levels of c-Myc. Notably, c-Myc mRNA expression was significantly upregulated in all groups, reaching a peak in group 1 (Fig.…”

Significance of MEF2C and RUNX3 Regulation for Endochondral Differentiation of Human Mesenchymal Progenitor Cells

“…A second limitation is the use of phenotypically abnormal osteosarcoma cells for knockdown studies in lack of a human model cell line closer to MPC chondrogenesis than SAOS-2 cells. Although we (Melnik et al, 2019) and others (Venkatesan et al, 2012;Frisch et al, 2014;De Kroon et al, 2017;Kim et al, 2019) successfully modified MPCs in monolayer culture by forced expression of transgenes, this approach is inapplicable in here, since chondrogenesis does not occur in 2D, but requires 3D culture. Importantly, our data demonstrate that microenvironmental cues like higher oxygen and/or better nutrient access were critical for MEF2C protein expression and ALP induction, while cells in the pellet center developed properly.…”

Bioinformatic analysis reveals MIR502 as a potential tumour suppressor in ovarian cancer

“…The MYC family of proto-oncogenes is comprised of c-MYC, MYCN and MYCL [40]. c-MYC as an oncogene in numerous cancer cells plays an important role in a myriad of biological processes, including cell growth, cell cycle progression and proliferation [41,42] by cooperating with YAP and activating a large number of target genes [43].…”