Tumour prevention and tumour progression: a dual role for statins?☆

www.sciencedirect.com The use of statins is essential for the treatment of hyperlipidemia as well as for the primary and secondary prevention of coronary artery disease and strokes. Statins decrease low-density lipoprotein (LDL) cholesterol levels by inhibiting 3-hydroxy-3-methyl-glutaryl-CoA HMG-CoA reductase (HMGCR). HMGCR in turn catalyses the conversion of HMG-CoA into mevalonic acid, an important intermediate metabolite in hepatic cholesterol biosynthesis. Statins exert pleiotropic effects independent of their cholesterol-lowering activity, which are in part mediated by mevalonic acid, a precursor of the isoprenoid intermediates farnesyl and geranyl-geranyl pyrophosphate [1]. These compounds participate in the post-translational modification of intracellular G-proteins, such as Rho, Rac, and Ras. In turn, it is well-known that G-proteins drive signalling pathways that are widely involved in carcinogenesis [2], and their inhibition by statins has been proven to efficiently impair the growth of several tumours [3]. Furthermore, statins inhibit cellular matrix metalloproteinases and nuclear factor-kB (NFkB) transcription factors that are, additionally, often deregulated in cancer. A large body of studies exists that support the efficacy of statins against several cancer types [3]. For this reason, these compounds has been proposed as adjuvant options in cancer therapies and in cancer prevention. Currently, recommendations and guidelines on statin use in malignancies do not exist; in addition, to date, results from randomised controlled trials are inconclusive regarding the question of whether cancer treatment may benefit from statins

FKBP51 in cancer

Overview sulla nostra ricerca condotta negli ultimi 10 anni, sul ruolo della immunofillina FKBP51 nel cancro, e particolarmente nel melanoma. Introduzione della nostra recente identificazione di una variante di splicing della proteina, fino al 2015 sconosciuta

An immunophenotype approach identified an unknown Treg subset in PBMC of melanoma patients, as associated with response to anti-CTLA4

Recently, our group demonstrated that the inhibitory immune checkpoint PD-L1/PD1 promoted the alternative splicing of FKBP5 gene, resulting in increased expression of its variant 4, in PBMC of melanoma patients. Such variant 4 is translated into a truncated protein, termed FKBP51s. Based on the relevant role for co-inhibitory signaling in tumor immune escape, we thought to measure the expression of such a molecular sensor of PD-L1/PD1 interaction in melanoma patients, by PBMC immunophenotyping. The study was conducted on a cohort of 118 patients and 77 age- and sex-matched healthy controls. Blood samples were collected before patients underwent ipilimumab treatment. In 64 out of 118 patients, expression of FKBP51s was also assessed in regulatory T cells. Our findings showed that, physiologically, each PBMC subset analyzed contained an FKBP51spos fraction, which resulted expanded in melanoma patients. CD4 T lymphocytes showed the FKBP51sneg subset significantly impaired. Treg count was increased, in accordance with previous studies. The study of FKBP51sposTregs allowed to identify a subgroup of nonresponder patients to ipilimumab (p=0.002). In conclusion, FKBP51s-based immunophenotype of melanoma patients revealed several profiles virtually related to a negative immune regulatory control and disclosed an unknown Treg subset potentially useful in the selection of patients candidate to immunotherapy

Activation of NF-kappaB/Rel transcription factors in human primary peripheral blood mononuclear cells by interleukin 7.

Pathways that regulate the activation of NF-kappaB/Rel transcription factors are known to include signaling through a number of cytokine receptors. Interleukin 7 (IL-7), produced by bone marrow and other stromal cells, is a key factor for differentiation and survival in the lymphoid and other compartments. We found that human recombinant IL-7 induced NF-kappaB/Rel activation, analyzed by electrophoretic mobility shift assay (EMSA), in human peripheral blood T lymphocytes from healthy donors. Induced complexes included p65 and p50 NF-kappaB/Rel subunits. These results demonstrate for the first time that IL-7 can participate in signaling leading to NF-kappaB/Rel activation

Enhancement of cytosine arabinoside-induced apoptosis in human myeloblastic leukemia cells by NFkB/Rel- specific decoy oligodeoxynucleotides

The activity of NF-kB/Rel nuclear factors is known to inhibit apoptosis in various cell types. We investigated whether the subtraction of NF-kB/Rel activity influenced the response of 11 AML (M1, M2 and M4) patients’ cells to AraC. To this end we used a phosphorothioate double-stranded decoy oligodeoxynucleotide (ODN) carrying the NF-kB/Rel- consensus sequence. Cell incubation with this ODN, but not its mutated (scrambled) form used as a control, resulted in abating the NF-kB/Rel nuclear levels in these cells, as verified by electrophoretic mobility shift assay (EMSA) of cells’ nuclear extracts. We incubated the leukemic cells with AraC (32 or 1 mM), in either the absence or presence of the decoy or the scrambled ODN, and analyzed cell apoptosis. The spontaneous cell apoptosis detectable in the absence of AraC (,25%) was not modulated by the oligonucleotide presence in cell cultures. On the other hand, in 10 of the 11 samples tested, the decoy kB, but not the scrambled ODN significantly (P ,0.01 in a Student’s t test) enhanced cell apoptotic response to AraC. Such an effect was particularly remarkable at low AraC doses (1 mM). These findings indicate that NF-kB/Rel activity influences response to AraC in human primary myeloblastic cells, and suggests that the inhibition of NF-kB/Rel factors can improve the effect of chemotherapy in AM

Identification of Drosophila Mitotic Genes by Combining Co-Expression Analysis and RNA Interference

RNAi screens have, to date, identified many genes required for mitotic divisions of Drosophila tissue culture cells. However, the inventory of such genes remains incomplete. We have combined the powers of bioinformatics and RNAi technology to detect novel mitotic genes. We found that Drosophila genes involved in mitosis tend to be transcriptionally co-expressed. We thus constructed a co-expression–based list of 1,000 genes that are highly enriched in mitotic functions, and we performed RNAi for each of these genes. By limiting the number of genes to be examined, we were able to perform a very detailed phenotypic analysis of RNAi cells. We examined dsRNA-treated cells for possible abnormalities in both chromosome structure and spindle organization. This analysis allowed the identification of 142 mitotic genes, which were subdivided into 18 phenoclusters. Seventy of these genes have not previously been associated with mitotic defects; 30 of them are required for spindle assembly and/or chromosome segregation, and 40 are required to prevent spontaneous chromosome breakage. We note that the latter type of genes has never been detected in previous RNAi screens in any system. Finally, we found that RNAi against genes encoding kinetochore components or highly conserved splicing factors results in identical defects in chromosome segregation, highlighting an unanticipated role of splicing factors in centromere function. These findings indicate that our co-expression–based method for the detection of mitotic functions works remarkably well. We can foresee that elaboration of co-expression lists using genes in the same phenocluster will provide many candidate genes for small-scale RNAi screens aimed at completing the inventory of mitotic proteins

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead.

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety 'Mode of Action' framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology