Gender-related invasion differences associated with mRNA expression levels of melatonin membrane receptors in colorectal cancer.

Melatonin inhibits growth and invasive capacity of colon cancer cells in vitro through its membrane (MT1 and MT2) and/or nuclear receptors (RORα). Previous studies showed that this indoleamine is present in both the normal and colon cancer at similar levels. Therefore, we analyzed MT1, MT2, and RORα expression in tumor samples versus normal mucosa (NM) from patients suffering from colorectal cancer (CRC). Given the existence of sex differences in the incidence and pathology of CRC and the involvement of steroid receptors in the oncostatic actions of melatonin in some types of cancer, we also analyzed the expression of androgen (AR) and estrogen receptor (ER) α and ERß. Finally, we conducted some experiments in colon cancer cell lines to corroborate the experiments carried out in human tumors. We found a decreased expression of MT1, MT2, AR, ERα, and ERß in tumor samples versus NM, but no changes in RORα expression in the whole cohort of patients. Classifying tumors by stage and gender, MT1, MT2, AR, ERα, and ERß expression decreased in both early stage and advanced tumors, but only in male patients. On the other hand, MT1 and MT2 expression correlated positively with AR, ERα, and ERß expression in male patients and with ERα or ERß in female patients. In vitro, the invasive capacity was higher in cells with the least expression of MT1, MT2, and AR, and nonselective MT1/MT2 agonists inhibited cell growth and invasion. These results could indicate a possible interaction of these pathways.

Vorinostat interferes with the signaling transduction pathway of T-cell receptor and synergizes with phosphoinositide-3 kinase inhibitors in cutaneous T-cell lymphoma.

BACKGROUND: Vorinostat (suberoylanilide hydroxamic acid, SAHA), an inhibitor of class I and II histone deacetylases, has been approved for the treatment of cutaneous T-cell lymphoma. In spite of emerging information on the effect of vorinostat in many types of cancer, little is yet known about this drug's mechanism of action, which is essential for its proper use in combination therapy. We investigated alterations in gene expression profile over time in cutaneous T-cell lymphoma cells treated with vorinostat. Subsequently, we evaluated inhibitors of PI3K, PIM and HSP90 as potential combination agents in the treatment of cutaneous T-cell lymphoma. DESIGN AND METHODS: The genes significantly up- or down-regulated by vorinostat over different time periods (2-fold change, false discovery rate corrected P value<0.05) were selected using the short-time series expression miner. Cell viability was assessed in vitro in cutaneous T-cell lymphoma cells through measuring intracellular ATP content. Drug interactions were analyzed by the combination index method with CalcuSyn software. RESULTS: The functional analysis suggests that vorinostat modifies signaling of T-cell receptor, MAPK, and JAK-STAT pathways. The phosphorylation studies of ZAP70 (Tyr319, Tyr493) and its downstream target AKT (Ser473) revealed that vorinostat inhibits phosphorylation of these kinases. With regards to effects on cutaneous T-cell lymphoma cells, combining vorinostat with PI3K inhibitors resulted in synergy while cytotoxic antagonism was observed when vorinostat was combined with HSP90 inhibitor. CONCLUSIONS: These results demonstrate the potential targets of vorinostat, underlining the importance of T-cell receptor signaling inhibition following vorinostat treatment. Additionally, we showed that combination therapies involving histone deacetylase inhibitors and inhibitors of PI3K are potentially efficacious for the treatment of cutaneous T-cell lymphoma.

Functional signatures identified in B-cell non-Hodgkin lymphoma profiles.

Gene-expression profiling in B-cell lymphomas has provided crucial data on specific lymphoma types, which can contribute to the identification of essential lymphoma survival genes and pathways. In this study, the gene-expression profiling data of all major B-cell lymphoma types were analyzed by unsupervised clustering. The transcriptome classification so obtained, was explored using gene set enrichment analysis generating a heatmap for B-cell lymphoma that identifies common lymphoma survival mechanisms and potential therapeutic targets, recognizing sets of coregulated genes and functional pathways expressed in different lymphoma types. Some of the most relevant signatures (stroma, cell cycle, B-cell receptor (BCR)) are shared by multiple lymphoma types or subclasses. A specific attention was paid to the analysis of BCR and coregulated pathways, defining molecular heterogeneity within multiple B-cell lymphoma types.

Identification of biological markers of sensitivity to high-clinical-risk-adapted therapy for patients with diffuse large B-cell lymphoma.

The aim of the project was to identify biological variables in high-clinical-risk patients with diffuse large B-cell lymphoma (DLBCL), treated with risk-adapted therapies. The study was performed in a series of high-clinical-risk patients with DLBCL treated with MegaCHOP or MegaCHOP + IFE followed by autologous stem-cell transplantation (ASCT). An initial reduced set of diagnostic tumoral samples was studied by gene expression profiling and gene-set-enrichment analysis. A set of potential biomarkers extracted from this study was then explored in tissue microarrays containing paraffin-diagnostic tissue from 50 patients. The statistical analysis identified 17 immunohistochemical markers associated with the clinical endpoints. A subsequent multivariate analysis identified FoxP3+ T-reg cells as an independent predictor of failure-free survival. Bcl6 expression, CG/ABC subclasses and IPI were found not to predict survival in this series. The increased presence of regulatory T-cells as a marker of adverse outcome highlights specific components of the tumoral microenvironment in the pathogenesis and treatment response prediction for high-clinical-risk patients with DLBCL.

Desmosterol can replace cholesterol in sustaining cell proliferation and regulating the SREBP pathway in a sterol-Delta24-reductase-deficient cell line.

Cholesterol homoeostasis is critical for cell viability and proliferation. The SREBP (sterol regulatory element-binding protein) pathway is crucial for the maintenance of cholesterol homoeostasis. This pathway is controlled by cholesterol and cholesterol-derived oxysterols. J774 cells cannot convert desmosterol into cholesterol, a defect resulting from the absence of mRNA for sterol-Delta24-reductase. Using J774 cells, we addressed the capacity of desmosterol to replace cholesterol in sustaining cell proliferation and regulating the SREBP pathway. J774 cells were able to grow indefinitely after the virtually total replacement of cholesterol by desmosterol (J774-D cells). Inhibition of sterol biosynthesis with lovastatin suppressed J774-D cell proliferation. Desmosterol prevented this effect, but its analogue, cholest-5,22-trans-dien-3beta-ol, did not. Addition of desmosterol inhibited processing of SREBP-1 and -2 and also reduced the expression of SREBP-targeted genes. As occurs in cholesterol-containing cells, 25-hydroxycholesterol was more potent than desmosterol or cholesterol in suppressing these processes. Moreover, desmosterol addition enhanced the expression of Abca1 and Srebf1c, two LXR (liver X receptor)-targeted genes. To test the ability of endogenously produced desmosterol to regulate gene expression, J774-D cells were pretreated with lovastatin to inhibit sterol biosynthesis. After removal of the inhibitor the expression of SREBP-targeted genes decreased and that of an LXR-targeted gene increased, reaching control levels. Our results demonstrate that the virtually complete replacement of cholesterol by desmosterol is compatible with cell growth and the functioning of the SREBP pathway. In these cells, desmosterol suppresses SREBP processing and targeted gene expression, and it is especially effective activating LXR-targeted genes.

Lentiviral (HIV)-based RNA interference screen in human B-cell receptor regulatory networks reveals MCL1-induced oncogenic pathways.

Aberrant inhibition of B-cell receptor (BCR)-induced programmed cell death pathways is frequently associated with the development of human auto-reactive B-cell lymphomas. Here, we integrated loss-of-function, genomic, and bioinformatics approaches for the identification of oncogenic mechanisms linked to the inhibition of BCR-induced clonal deletion pathways in human B-cell lymphomas. Lentiviral (HIV)-based RNA interference screen identified MCL1 as a key survival molecule linked to BCR signaling. Loss of MCL1 by RNA interference rendered human B-cell lymphomas sensitive to BCR-induced programmed cell death. Conversely, MCL1 overexpression blocked programmed cell death on BCR stimulation. To get insight into the mechanisms of MCL1-induced survival and transformation, we screened 41 000 human genes in a genome-wide gene expression profile analysis of MCL1-overexpressing B-cell lymphomas. Bioinformatic gene network reconstruction illustrated reprogramming of relevant oncoproteins within beta-catenin-T-cell factor signaling pathways induced by enforced MCL1 expression. Overall, our findings not only illustrate MCL1 as an aberrantly expressed reprogramming oncoprotein in follicular lymphomas but also highlight MCL1 as key therapeutic target.

Tumor microenvironment and mitotic checkpoint are key factors in the outcome of classic Hodgkin lymphoma.

Around 20% to 30% of patients with Hodgkin lymphoma (HL) do not benefit from standard therapies and finally succumb to their disease. The factors that influence the outcome of HL have not been elucidated, underscoring the demand for the identification of biologic risk factors and new therapeutic targets. We analyzed the gene expression profiles of samples from 29 patients with advanced classic HL treated with standard therapy and compared the expression profiles of patients with favorable and unfavorable clinical outcome. Using supervised methods, we identified 145 genes associated with outcome, which were grouped into 4 signatures representing genes expressed by either the tumoral cells (genes involved in the regulation of mitosis and cell growth/apoptosis) or the tumor microenvironment. The relationship between the expression of 8 representative genes and survival was successfully validated in an independent series of 235 patients by quantification of protein expression levels on tissue microarrays. Analysis of centrosomes and mitotic checkpoint confirmed the existence of an abnormal transition through mitosis in HL cells. Therefore, genes related to tumor microenvironment, cell growth/apoptosis, and regulation of mitosis are associated with treatment response and outcome of patients with HL.