Abstract: |
Ki-1 (CD30)+ cutaneous T-cell lymphomas (CTCLs) are slowly progressive lymphomas in which initial spontaneous regression is often observed. To better understand the mechanisms of spontaneous regression and eventual tumor progression in Ki-1+ CTCLs, type β transforming growth factor (TGF-β)- mediated growth inhibition of clonally related cell lines derived from two time points, before and after tumor progression, was studied. TGF-β1 inhibited colony-forming efficiency (CFE) of a cell line (Mac-1) derived from clinically indolent Ki-1+ CTCLs but failed to inhibit CFE of Mac-2A and -2B cell lines from advanced CTCLs. To determine the basis for TGF-β1 resistance in advanced CTCL cells, we looked for possible defects in the expression of cell surface TGF-β receptors. Mac-1 cells were found to express TGF-β receptors I and II, which mediate growth inhibition, and the TGF-β-binding proteoglycan betaglycan. In contrast, receptors I and II were not detected in CTCL lines Mac-2A and -2B even though these cell lines did express betaglycan. Various treatments that unmask or induce TGF-β receptors in other cells failed to show evidence for these receptors in advanced CTCL cells. Loss of TGF-β receptor expression in these cells correlated with a marked decrease in TGF-β receptor II mRNA levels. Loss of cell surface TGF- β receptors was also found in two of five other patients with T-cell lymphomas including the Sezary syndrome and a noncutaneous T-cell lymphoma, suggesting that loss of TGF-β receptor expression may be a recurrent feature of human T-cell malignancies. |
Keywords: |
adult; human cell; case report; comparative study; t-lymphocytes; transforming growth factor beta; cell line; tumor cells, cultured; skin; cancer regression; t cell lymphoma; lymphoma, t-cell; molecular sequence data; receptors, transforming growth factor beta; base sequence; tumor growth; tumor suppressor genes; blotting, northern; skin lymphoma; growth inhibitors; sezary syndrome; growth factor receptor; tumor stem cell assay; lymphoma, t-cell, cutaneous; messenger rna synthesis; lymphomatoid papulosis; human; male; priority journal; article; support, non-u.s. gov't; support, u.s. gov't, p.h.s.; growth factor receptors
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