Normal and Cancer Fibroblasts Differentially Regulate Cytokine Genes and TWIST1 and TOX  Expression in Cutaneous T-cell Lymphoma 

Abstract Background : Mycosis fungoides (MF) is a primary cutaneous T-cell lymphoma (CTCL) that transforms from mature, skin-homing T cells and progresses in the skin. The role of the skin microenvironment in MF development is unclear, but recent findings in a variety of cancers have highlighted the role of stromal fibroblasts in promoting or inhibiting tumorigenesis. Stromal fibroblast are an important part of the cutaneous tumor microenvironment (TME) in MF. Here we describe studies into the interaction of TME-fibroblasts and malignant T cells to gain insight into their role in CTCL. Methods : Myla cell is a CTCL cell line that retains expression of biomarkers TWIST1 and TOX that are frequently detected in CTCL patients. MyLa cells were cultured in the presence or absence of normal or MF skin derived fibroblasts for 5 days, trypsinized to detached Myla cells, and gene expression analyzed by RT-PCR for MF biomarkers ( TWIST1 and TOX ), Th1 markers ( IFN-g , TBX21 ), Th2 markers ( GATA3 , IL-16 ), and proliferation marker ( MKI67 ). Purified fibroblasts were assayed for expressed genes VIM and ACTA2 . Cellular senescence assay was performed to assess senescence. Results : Normal fibroblasts co-cultured with MyLa cells suppressed expression of the CTCL biomarkers TWIST1 ( p < 0.0006) and TOX ( p <0.03) in MyLa cells . In contrast, MyLa cells cultured with MF fibroblasts retained high expression of TWIST1 and TOX . Normal fibroblasts increased expression of IFN-g ( p < 0.03) and TBX21 , and decreased expression of GATA3 ( p < 0.02) and IL-16 ( p < 0.03) in MyLa cells, whereas MF fibroblasts suppressed IFN-g and TBX21 and increased TWIST1 and TOX expression in MyLa cells. Furthermore, expression of MKI67 in MyLa cells was suppressed to a greater degree by normal fibroblasts compared to MF fibroblasts. Conclusions : Skin fibroblasts represent important components of the microenvironment in MF. In co-culture model, normal and cancer fibroblasts in MF have differential influence on T cell phenotype in modulating expression of Th1 cytokine and CTCL biomarker genes to reveal distinct role with implications in MF progression.