One of the most exciting areas of current research in the cannabinoid field is the study of the potential application of these compounds as antitumoral drugs. Here, we describe the signaling pathway that mediates cannabinoid-induced apoptosis of tumor cells. By using a wide array of experimental approaches, we identify the stress-regulated protein p8 (also designated as candidate of metastasis 1) as an essential mediator of cannabinoid antitumoral action and show that p8 upregulation is dependent on de novo-synthesized ceramide. We also observe that p8 mediates its apoptotic effect via upregulation of the endoplasmic reticulum stress-related genes ATF-4, CHOP, and TRB3. Activation of this pathway may constitute a potential therapeutic strategy for inhibiting tumor growth.

Polymerase chain reaction (PCR) assessment of clonal immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements is an important diagnostic tool in mature B-cell neoplasms. However, lack of standardized PCR protocols resulting in a high level of false negativity has hampered comparability of data in previous clonality studies. In order to address these problems, 22 European laboratories investigated the Ig/TCR rearrangement patterns as well as t(14;18) and t(11;14) translocations of 369 B-cell malignancies belonging to five WHO-defined entities using the standardized BIOMED-2 multiplex PCR tubes accompanied by international pathology panel review. B-cell clonality was detected by combined use of the IGH and IGK multiplex PCR assays in all 260 definitive cases of B-cell chronic lymphocytic leukemia (n ¼ 56), mantle cell lymphoma (n ¼ 54), marginal zone lymphoma (n ¼ 41) and follicular lymphoma (n ¼ 109). Two of 109 cases of diffuse large B-cell lymphoma showed no detectable clonal marker. The use of these techniques to assign cell lineage should be treated with caution as additional clonal TCR gene rearrangements were frequently detected in all disease categories. Our study indicates that the BIOMED-2 multiplex PCR assays provide a powerful strategy for clonality assessment in B-cell malignancies resulting in high Ig clonality detection rates particularly when IGH and IGK strategies are combined.

Mycosis fungoides (MF) is the most frequent type of cutaneous T-cell lymphoma, whose diagnosis and study is hampered by its morphologic similarity to inflammatory dermatoses (ID) and the low proportion of tumoral cells, which often account for only 5% to 10% of the total tissue cells. cDNA microarray studies using the CNIO OncoChip of 29 MF and 11 ID cases revealed a signature of 27 genes implicated in the tumorigenesis of MF, including tumor necrosis factor receptor (TNFR)-dependent apoptosis regulators, STAT4, CD40L, and other oncogenes and apoptosis inhibitors. Subsequently a 6-gene prediction model was constructed that is capable of distinguishing MF and ID cases with unprecedented accuracy. This model correctly predicted the class of 97% of cases in a blind test validation using 24 MF patients with low clinical stages. Unsupervised hierarchic clustering has revealed 2 major subclasses of MF, one of which tends to include more aggressive-type MF cases including tumoral MF forms. Furthermore, signatures associated with abnormal immunophenotype (11 genes) and tumor stage disease IntroductionMycosis fungoides (MF) is a peripheral cutaneous T-cell lymphoma (CTCL) characterized by the infiltration and accumulation of tumoral T cells in the skin (epidermal and dermal infiltration). 1 It is the most frequent type of CTCL, representing more than half of all lymphomas originating in the skin. 2 Clinical and pathologic diagnosis of MF has proved very difficult since it bears many resemblances to common inflammatory dermatoses (ID) such as interface and spongiotic dermatitis, conditions involving infiltration and accumulation of benign T cells in the skin. The study of MF is further compounded by the small number of tumoral cells, which may be present in the skin, with tumoral T-cell infiltrate often accounting for only 5% to 10% of the total tissue cells. Most CTCLs have the phenotype of T-helper memory lymphocytes (CD3 ϩ , CD4 ϩ ) with only a minority of cases showing phenotypes such as CD4 Ϫ or CD8 ϩ , with CD8 ϩ cases possibly representing a subset of aggressive cases. 3 Additionally, loss of CD7 expression is considered a distinguishing characteristic of MF. 4 The etiology of MF remains largely unknown, although some triggering factors such as chronic antigen stimulation 5 or human T-cell lymphotropic virus type 1 or other viral infections have been proposed. However, some of these findings have been somewhat contentious. 6,7 Molecular studies of MF have revealed some interesting facts, although the studies are confined to small groups of genes and proteins. Defective FAS signaling has been suggested as a possible causative agent in MF pathogenesis due to defects in apoptosis signaling in skin-homing T cells. 8 Reduction of FAS expression has been documented in peripheral blood CD4 ϩ T lymphocytes in CTCL. 9 This decreased FAS expression may be the result of FAS mutations, which are infrequent but are present in some cases. 8 Defective FAS signaling may also be supplemented by mutations or defects in caspases or ...

Poly(ADP-ribose) polymerase (PARP)-1, an enzyme that catalyzes the attachment of ADP ribose to target proteins, acts as a component of enhancer/promoter regulatory complexes. In the present study, we show that pharmacologic inhibition of PARP-1 with 3,4-dihydro-5-[4-(1-piperidinyl)butoxyl]-1(2H)-isoquinolinone (DPQ) results in a strong delay in tumor formation and in a dramatic reduction in tumor size and multiplicity during 7,12-dimethylbenz(a)anthracene plus 12-O-tetradecanoylphorbol-13-acetate-induced skin carcinogenesis. This observation was parallel with a reduction in the skin inflammatory infiltrate in DPQ-treated mice and tumor vasculogenesis. Inhibition of PARP also affected activator protein-1 (AP-1) activation but not nuclear factor-KB (NF-KB). Using cDNA expression array analysis, a substantial difference in key tumor-related gene expression was found between chemically induced mice treated or not with PARP inhibitor and also between wild-type and parp-1 knockout mice. Most important differences were found in gene expression for Nfkbiz, S100a9, Hif-1a, and other genes involved in carcinogenesis and inflammation. These results were corroborated by real-time PCR. Moreover, the transcriptional activity of hypoxia-inducible factor-1A (HIF-1A) was compromised by PARP inhibition or in PARP-1-deficient cells, as measured by gene reporter assays and the expression of key target genes for HIF-1A. Tumor vasculature was also strongly inhibited in PARP-1-deficient mice and by DPQ. In summary, this study shows that inhibition of PARP on itself is able to control tumor growth, and PARP inhibition or genetic deletion of PARP-1 prevents from tumor promotion through their ability to cooperate with the activation AP-1, NF-KB, and HIF-1A.

The CDKN2A gene located on chromosome region 9p21 encodes the cyclin-dependent kinase-4 inhibitor p16/INK4A, a negative cell cycle regulator. We analyzed p16/INK4A expression in different types of non-Hodgkin's lymphoma to determine whether the absence of this protein is involved in lymphomagenesis, while also trying to characterize the genetic events underlying this p16/INK4A loss. To this end, we investigated the levels of p16/INK4A protein using immunohistochemical techniques in 153 cases of non-Hodgkin's lymphoma, using as reference the levels found in reactive lymphoid tissue. The existence of gene mutation, CpG island methylation, and allelic loss were investigated in a subset of 26 cases, using single-strand conformational polymorphism and direct sequencing, Southern Blot, polymerase chain reaction, and microsatellite analysis, respectively. Loss of p16/INK4A expression was detected in 41 of the 112 non-Hodgkin's lymphomas studied (37%), all of which corresponded to high-grade tumors. This loss of p16/INK4A was found more frequently in cases showing tumor progression from mucosa-associated lymphoid tissue low-grade lymphomas (31 of 37) or follicular lymphomas (4 of 4) into diffuse large B-cell lymphomas. Analysis of the status of the p16/INK4A gene showed different genetic alterations (methylation of the 5'-CpG island of the p16/INK4A gene, 6 of 23 cases; allelic loss at 9p21, 3 of 16 cases; and nonsense mutation, 1 of 26 cases). In all cases, these events were associated with loss of the p16/INK4A protein. No case that preserved protein expression contained any genetic change. Our results demonstrate that p16/INK4A loss of expression contributes to tumor progression in lymphomas. The most frequent genetic alterations found were 5'-CpG island methylation and allelic loss.

Interferon-alpha therapy has been shown to be active in the treatment of mycosis fungoides although the individual response to this therapy is unpredictable and dependent on essentially unknown factors. In an effort to better understand the molecular mechanisms of interferon-alpha resistance we have developed an interferon-alpha resistant variant from a sensitive cutaneous T-cell lymphoma cell line. We have performed expression analysis to detect genes differentially expressed between both variants using a cDNA microarray including 6386 cancer-implicated genes. The experiments showed that resistance to interferon-alpha is consistently associated with changes in the expression of a set of 39 genes, involved in signal transduction, apoptosis, transcription regulation, and cell growth. Additional studies performed confirm that STAT1 and STAT3 expression and interferon-alpha induction and activation are not altered between both variants. The gene MAL, highly overexpressed by resistant cells, was also found to be expressed by tumoral cells in a series of cutaneous T-cell lymphoma patients treated with interferon-alpha and/or photochemotherapy. MAL expression was associated with longer time to complete remission. Time-course experiments of the sensitive and resistant cells showed a differential expression of a subset of genes involved in interferon-response (1 to 4 hours), cell growth and apoptosis (24 to 48 hours.), and signal transduction.

Splenic marginal zone lymphoma (SMZL) has been recognized as an entity defined on the basis of its morphological , phenotypic , and clinical characteristic features. Nevertheless , no characteristic genetic alterations have been described to date for this entity, thus making an exact diagnosis of SMZL difficult in some cases. As initial studies showed that chromosome region 7q22-32 is deleted in some of these cases, we analyzed a larger group of SMZL and other lymphoproliferative disorders that may partially overlap with it. To better define the frequency of 7q deletion in SMZL and further identify the deleted region , polymerase chain reaction analysis of 13 microsatellite loci spanning 7q21-7q36 was performed on 20 SMZL and 26 non-SMZL tissue samples. The frequency of allelic loss in SMZL (8/20; 40%) was higher than that observed in other B-cell lymphoproliferative syndromes (2/26; 7.7%). This difference was statistically significant (P < 0.05). The most frequently deleted microsatellite was D7S487 (5/11; 45% of informative cases). Surrounding this microsatellite the smallest common deleted region of 5cM has been identified, defined between D7S685 and D7S514. By comparative multiplex polymerase chain reaction analysis , we detected a homozygous deletion in the D7S685 (7q31.

Summary B-cell high-grade lymphomas are heterogeneous in terms of histology, clinical presentation, treatment response and prognosis. As bcl-2 and p53 gene deregulations are frequencly involved in several types of lymphoid malignancies, we aimed our investigation at the study of the relation between bcl-2 and p53 expression and survival probability in a group of 119 patients with B-cell high-grade lymphoma. These were obtained from the Virgen de la Salud Hospital, Toledo, Spain (73 cases), John Radcliffe Hospital, Oxford, UK (31 cases), and the Istituto Nazionale dei Tumori, Milan, Italy (15 cases). The relation between bcl-2 protein expression and survival was small, depending on the primary localisation of the tumour (in lymph node of mucosae), and lacked a significant correlation with overall survival. In contrast with this, p53 expression was related to survival probability in our series, this relation being both significant and independent of histological diagnosis. p53-positive patients showed a sudden decrease in life expectancy in the first months after diagnosis. Multivariant regression analysis confirmed that the only parameters significantly related with survival were extranodal origin, which is associated with a better prognosis, and p53 expression, which indicates a poor prognosis. Simultaneous expression of bcl-2 and p53 was associated with a poorer prognosis than p53 alone. This is particularly significant for large B-cell lymphomas presenting in lymph nodes. The cumulative poor effect of both p53 and bcl-2 in large B-cell lymphomas, which is more significant in nodal tumours, could confirm the existence of a multistep genetic deregulation in non-Hodgkin's lymphoma. This indicates that the genetic mechanisms controlling apoptosis and their disregulation are critical steps in the progression of lymphomas.