Using a cDNA microarray, we compared the expression of approximately 8000 genes between two unique, clonally related T cell lines derived from different stages of a progressive T cell lymphoma involving skin. differential expression identified by the cDNA microarray analysis was confirmed for selected genes by reverse transcription-polymerase chain reaction and Northern blotting. The identified differences in gene expression may be related to the differences in behavior between the early and advanced stages of the T cell lymphoma and point to directions for further investigations into mechanisms of lymphoma progression. Cutaneous T cell lymphoma is the most common lymphoproliferative disorder involving skin. It usually is an indolent, low-grade tumor at the time of presentation. Over time, the CTCL often undergoes transformation to an aggressive, usually fatal high-grade large cell lymphoma. 1 Although dysregulation of p53 and p16INK4a tumor suppressor genes has been implicated in the lymphoma progression, 2,3 the exact molecular mechanism underlying the large cell transformation of cutaneous T cell lymphoma as well as other lymphoid malignancies remains poorly defined. Recently, complementary DNA (cDNA) microarrays have been used to identify physiologically and pathologically relevant gene expression patterns in a variety of organisms including humans. 4-12 This new technology is based on the fluorescence hybridization in which two different cDNA populations (each labeled with either red or green fluorochrome) are hybridized simultaneously with a microarray containing thousands of deposited cDNA fragments. The ratio of fluorescence intensity (red/green) represents the ratio of concentrations of mRNA molecules that hybridize to each of the cDNAs spotted on the array. In contrast to the traditional molecular techniques that focus on one to a few genes at a time, cDNA microarrays allow gene expression patterns to be analyzed on a genomic scale. We have previously established two clonally related T cell lymphoma cell lines from a patient with a progressive cutaneous T cell lymphoproliferative disorder. PB1 cell line was established from a relatively early, indolent Rabbit polyclonal to Sca1 stage lymphoma, and buy PF 4708671 2A cell line was derived from the same lymphoma at a later, histologically high-grade, and clinically aggressive stage. 13-15 The cell lines are representative of the primary tumors and retain the morphological, immunophenotypic, and genotypic features of the original lymphoma. In the present study, we compared the gene expression profiles between these two cell lines using a cDNA microarray to investigate molecular changes related to lymphoma progression. Materials and Methods Cell Lines PB1, 2A, and 2B T cell lymphoma cell lines, established from a single patient with a progressive cutaneous T cell lymphoproliferative disorder, have been described in detail previously. 13-15 In brief, the PB1 cell line was obtained at a relatively early stage of the lymphoma from neoplastic T cells circulating in the peripheral blood. The 2A and 2B cell lines were established 2 years later at a clinically aggressive lymphoma stage from two separate skin nodules, which contained high-grade, anaplastic large T cell lymphoma. The common clonal origin of these three T cell lines was demonstrated by cytogenetic and T cell receptor gene rearrangement studies, which were identical to those, found in the patients lymphoma tissues. The cell lines were essentially identical to fresh biopsy specimens in regard to morphology, immunophenotype and genotype and retained in culture features of the original lymphoma cells. Sez4 cell line was derived from a patient with Sezary syndrome and also bears close morphological, immunophenotypic, and genotypic resemblance to the original tumor. 16 JB6, SUDHL-1, SUP-M2 and KARPAS299 cell lines were derived from four different NPM/ALK-positive large T/null-cell lymphomas. 17,18 HUT102 and C10MJ cell lines represent HTLV-1-related acute T cell lymphoma/leukemia. 16 L428 and HS445 cell lines were obtained from patients with Hodgkin lymphoma. 19 The exact nature of the HS445 line is uncertain. Although derived from patient with Hodgkin lymphoma, this buy PF 4708671 line may represent an Epstein-Barr virus (EBV)-transformed lymphoblastoid B cell line. 20 20A represents an EBV-transformed low-grade B cell lymphoma cell line and BCBL cell line was derived from an EBV-positive large B cell lymphoma. 21 The MOLT4 cell line represents an acute T cell lymphoblastic leukemia. 20 All cell lines were maintained at 37C in RPMI1640 supplemented with 10% heat-inactivated fetal calf serum. cDNA Clones The 9703 human cDNA clones used in these experiments were obtained from Research Genetics (Huntsville, AL) as bacterial colonies buy PF 4708671 in 96-well microtiter plates. 9 Approximately 8000 distinct Unigene clusters (representing nominally unique genes) were represented in this set of clones. To buy PF 4708671 date, the identities of approximately 3000 clones have been confirmed by us by re-analysis of the clone DNA sequence..