Microarray analysis of gene expression by microdissected epidermis and dermis in mycosis fungoides and adult T-cell leukemia/lymphoma

The characteristic histopathological feature of mycosis fungoides (MF) and adult T-cell leukemia/lymphoma (ATLL) is epidermotropism. To identify the mechanism for epidermotropism of lymphoma cells, total RNAs were obtained from skin biopsies of epidermis and dermis of MF and ATLL patients by means of laser capture microdissection, and used for subsequent complementary DNA (cDNA) microarray experiments. This procedure has made it possible for us to observe and evaluate the regional environment of MF and ATLL. Hierarchical cluster analysis revealed that the cDNAs could be clearly differentiated into MF and ATLL. CCL27 was expressed in the dermis generated from keratinocytes, CCR4/CCR6/CCR7/CCR10/cutaneous lymphocyte-associated antigen (CLA) lymphoma cells in the dermis, and CCL21 in the extracellular matrix (stroma). Lymphotoxin (LT) β and CCL21 expression was significantly higher and that of CCR10 relatively for MF, while CCR4 and CLA expression was relatively higher for ATLL. In the epithelium, keratinocytes expressed CCL20/CCL27, and lymphoma cells CCR4/CCR6/CCR10, while CCR4, CCR6, CCL20 and CCL27 expression was relatively higher for ATLL than MF. The dermis of MF, but not that of ATLL, showed correlation between CCR7 and CCL21. These findings support the suggestion that chemokines and chemokine receptors are involved in the pathogenesis of MF and ATLL, indicate that cutaneous homing seems to be different for MF and ATLL, and point to the possibility that cutaneous T-cell lymphomas originate in regulatory T cells, especially in the case of ATLL.