Disparate Response to Methotrexate in Stem Versus Non-Stem Cells

Abstract

Methotrexate (MTX) is a commonly used chemotherapeutic agent that kills cancer cells by binding dihydrofolate reductase (DHFR) as a competitive inhibitor. Due to its non-selectivity, MTX also impairs normal (non-cancerous) cell function and causes long-term damage to healthy tissue. These consequences have been investigated extensively in bone-derived cells due to their sensitivity to the drug. While DHFR likely plays a role in normal cell response to MTX, research in this area is limited. Moreover, how MTX sensitivity differs among cell types responsible for maintaining connective tissues is unknown. The goal of this study was to investigate the role of DHFR and subsequent nucleotide synthesis in normal cell response to MTX. We also sought to compare adverse effects of MTX among normal cell types to identify sensitive populations and resistant cell sources for regenerative procedures targeting patients undergoing chemotherapy. DHFR overexpression or exogenous amino acid + nucleoside delivery rescued normal cells from adverse MTX effects. Conversely, DHFR knockdown impaired MTX-treated adipose-derived stem cell (ASC) osteogenesis. Proliferation of ASCs and bone marrow stem cells was more resistant to MTX than that of terminally differentiated osteoblasts. However, stem cells became susceptible to the drug after beginning differentiation. These results suggest that the ability of stem cells to survive and to maintain their surrounding tissues likely depends on whether they are in a “stem” state when exposed to MTX. Therapeutic strategies that delay the differentiation of stem cells until clearance of the drug may produce more favorable outcomes in the long-term health of treated tissues.

Assessment and Comparison of the Efficacy of Methotrexate, Prednisolone, Adalimumab, and Tocilizumab on Multipotency of Mesenchymal Stem Cells

“…Methotrexate functionally inhibits the de novo synthesis of purines and pyrimidines that is required for DNA and RNA synthesis, as well as cell proliferation. In our study, in vitro treatment with methotrexate significantly suppressed the multilineage (adipogenic, osteogenic, and chondrogenic) potencies of MSCs, consistent with the results of a previous study ( Beane et al., 2016 ). Undifferentiated stem cells exhibited resistance to methotrexate; even concentrations of methotrexate as high as 50 μM did not affect cell proliferation.…”

Paclitaxel’s Mechanistic and Clinical Effects on Breast Cancer

“…Regarding enzymes that the antimetabolites suppress, they are classified into inhibitors of dehydrogenases, topoisomerases, nucleosides, and kinases [41,42]. Methotrexate is a dehydrogenase inhibitor, which acts as a competitive inhibitor of DHFR (dihydrofolate reductase) leading to accumulation of folate and subsequent inhibition of synthesis [43]. Doxorubicin represents the class of topoisomerase II inhibitors with a crucial role in the inhibition of topoisomerase II, formation of DNA adducts, and generation of oxidative stress [44].…”

LncRNA‐PCAT1 targeting miR‐145‐5p promotes TLR4‐associated osteogenic differentiation of adipose‐derived stem cells

“…Human adipose-derived stem cells (hADSCs) are regenerative cells locating in adipose tissue, with multilineage differentiation potentials. 1 hADSCs can facilitate the metabolism and maintenance of tissues through adipocytes replacement and promote angiogenesis. 2,3 As an important cell type, they possess great potential to be applied to cell-based therapies.…”