Comparative gene expression profiling of cutaneous B cell lymphomas

The oncogenic microRNA 17-92 cluster is involved in the lymphomagenesis of nodal and systemic B cell lymphomas, but has not been studied so far in primary cutaneous B cell lymphomas. We performed the quantitative analysis of miR-17-92 cluster and its paralogs miR-106a-363 and miR-106b-25 in 22 primary cutaneous diffuse large B-cell lymphomas-leg type (PCLBCL-LT) and 22 primary cutaneous follicle center lymphomas (PCFCL). Mir-20a and miR-106a were overexpressed in PCLBCL-LT compared to PCFCL. Multivariate Cox analysis showed that higher miR-20a and miR-20b were associated with poorer disease-free survival and poorer overall survival, independently of histological type. Gene expression profiling showed underexpression of 8 candidate target genes of miR-20a, miR-20b and miR-106a in PCLBCL-LT compared to PCFCL. Among the candidate target genes, PTEN, NCOA3 and CAPRIN2 were confirmed to be underexpressed in PCLBCL-LT using quantitative RT-PCR of laser-microdissected tumor cells. In multivariate Cox analysis, lower PTEN mRNA expression level was associated with poorer disease-free survival, independently of the histological type. Altogether, this molecular and bioinformatics study of patients’ skin biopsy samples showed that the oncogenic miR-17-92 cluster is involved in cutaneous B cell lymphoma progression, and that the down-regulation of its target gene PTEN is associated with poorer disease-free survival. 10 skin samples from patients were analyzed. 6 were PCLBCL-leg type and 4 PCFCL.