| Abstract: |
All-trans retinoic acid (RA) exerts profound effects on the growth and differentiation of normal, embryonic, and malignant cells. The effects of RA are mediated through multiple members of the retinoic acid receptor (RAR) and retinoid X receptor (RXR) families of nuclear transcription factors. The RARs and RXRs exhibit specific patterns of expression during development and in adult tissues suggesting tissue or cell-type specific functions. Using NTera2/clone D1 (NT2/D1) human embryonal carcinoma cells as a model, we report that the RA induced terminal differentiation of these cells into a neuronal phenotype is characterized by an increase in expression of RARα, RARβ, RARγ, and a slight induction of RXRα. To study the role of these receptors in the differentiation process we individually overexpressed RARα, β, γ and RXRα in NT2/D1 cells by cDNA transfection. Using induced cDNA expression by episomal vector amplification we show that RARγ overexpression causes the terminal mesenchymal differentiation of these cells while over-expresssion of RARα, β and RXRα has no observed maturation or growth inhibitory effects. Over-expression of these receptors in the derived RA resistant subclone NT2/D1-R1 showed phenotypic changes characteristic of RA response in RARγ, transfectants. These studies indicate that of the retinoid receptors expressed in RA-treated NT2/D1 cells, it is the upregulation of RARγ that specifically induces the terminal differentiation of these cells. |
| Keywords: |
controlled study; human cell; nonhuman; cells, cultured; gene amplification; transcription factor; cell differentiation; cancer cell culture; molecular sequence data; base sequence; plasmids; cell clone; nerve cell differentiation; retinoic acid; embryonal carcinoma; mesenchyme; complementary dna; dna, complementary; retinoic acid receptor; tretinoin; receptors, retinoic acid; tumor stem cells; receptor subunit; dna transfection; human; priority journal; article; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; differentiaition; episomal vector; rarγ; retinoic carcinoma; episome
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