N-Aryl-N'-(chroman-4-yl)ureas and thioureas display in vitro anticancer activity and selectivity on apoptosis-resistant glioblastoma cells: screening, synthesis of simplified derivatives, and structure-activity relationship analysis.

A series of chroman derivatives previously reported as potassium channel openers, as well as some newly synthesized simplified structures, were examined for their in vitro effects on the growth of three human high-grade glioma cell lines: U373, T98G, and Hs683. Significant in vitro growth inhibitory activity was observed with 2,2-dimethylchroman-type nitro-substituted phenylthioureas, such as compounds 4o and 4p. Interestingly, most tested phenylureas were found to be slightly less active, but more cell selective (normal versus tumor glial cells, such as 3d, 3e, and 3g), thus less toxic, than the corresponding phenylthioureas. No significant differences were observed in terms of chroman-derivative-induced growth inhibitory effects between glioma cells sensitive to pro-apoptotic stimuli (Hs683 glioma cells) and glioma cells associated with various levels of resistance to pro-apoptotic stimuli (U373 and T98G glioma cells), a feature that suggests non-apoptotic-mediated growth inhibition. Flow cytometry analyses confirmed the absence of pro-apoptotic effects for phenylthioureas and phenylureas when analyzed in U373 glioma cells and demonstrated U373 cell cycle arrest in the G0/G1 phase. Computer-assisted phase-contrast videomicroscopy revealed that 3d and 3g displayed cytostatic effects, while 3e displayed cytotoxic ones. As a result, this work identified phenylurea-type 2,2-dimethylchromans as a new class of antitumor agents to be further explored for an innovative therapeutic approach for high-grade glioma and/or for a possible new mechanism of action

DIAPH3 predicts survival of patients with MGMT-methylated glioblastoma

BackgroundGlioblastoma is one of the most aggressive primary brain tumors, with a poor outcome despite multimodal treatment. Methylation of the MGMT promoter, which predicts the response to temozolomide, is a well-established prognostic marker for glioblastoma. However, a difference in survival can still be detected within the MGMT methylated group, with some patients exhibiting a shorter survival than others, emphasizing the need for additional predictive factors.MethodsWe analyzed DIAPH3 expression in glioblastoma samples from the cancer genome atlas (TCGA). We also retrospectively analyzed one hundred seventeen histological glioblastomas from patients operated on at Saint-Luc University Hospital between May 2013 and August 2019. We analyzed the DIAPH3 expression, explored the relationship between mRNA levels and Patient’s survival after the surgical resection. Finally, we assessed the methylation pattern of the DIAPH3 promoter using a targeted deep bisulfite sequencing approach.ResultsWe found that 36% and 1% of the TCGA glioblastoma samples exhibit copy number alterations and mutations in DIAPH3, respectively. We scrutinized the expression of DIAPH3 at single cell level and detected an overlap with MKI67 expression in glioblastoma proliferating cells, including neural progenitor-like, oligodendrocyte progenitor-like and astrocyte-like states. We quantitatively analyzed DIAPH3 expression in our cohort and uncovered a positive correlation between DIAPH3 mRNA level and patient’s survival. The effect of DIAPH3 was prominent in MGMT-methylated glioblastoma. Finally, we report that the expression of DIAPH3 is at least partially regulated by the methylation of three CpG sites in the promoter region.ConclusionWe propose that combining the DIAPH3 expression with MGMT methylation could offer a better prediction of survival and more adapted postsurgical treatment for patients with MGMT-methylated glioblastoma

Prognostic impact of vitamin B6 metabolism in lung cancer

Patients with non-small cell lung cancer (NSCLC) are routinely treated with cytotoxic agents such as cisplatin. Through a genome-wide siRNA-based screen, we identified vitamin B6 metabolism as a central regulator of cisplatin responses in vitro and in vivo. By aggravating a bioenergetic catastrophe that involves the depletion of intracellular glutathione, vitamin B6 exacerbates cisplatin-mediated DNA damage, thus sensitizing a large panel of cancer cell lines to apoptosis. Moreover, vitamin B6 sensitizes cancer cells to apoptosis induction by distinct types of physical and chemical stress, including multiple chemotherapeutics. This effect requires pyridoxal kinase (PDXK), the enzyme that generates the bioactive form of vitamin B6. In line with a general role of vitamin B6 in stress responses, low PDXK expression levels were found to be associated with poor disease outcome in two independent cohorts of patients with NSCLC. These results indicate that PDXK expression levels constitute a biomarker for risk stratification among patients with NSCLC.publishedVersio

How do reactive oxygen species and calcium trigger mitochondrial membrane permeabilisation?

Mitochondrial membrane permeabilisation (MMP) is classically considered as a point of no return in several forms of cell death and is involved in numerous diseases such as cancer, neurodegenerative disorders or ischemia/reperfusion injuries. Many studies established that reactive oxygen species (ROS) and Ca(2+) were the prominent inducers of MMP. However, the mechanisms connecting ROS and Ca(2+) to the players of MMP are still a matter of debate

Effects of the expression of PRAME in cancer cell proliferation and apoptosis

Preferentially expressed antigen of melanoma (PRAME) is expressed in wide variety of tumors, but in contrast with most other tumor-associated antigens, it is also expressed in leukaemias. The physiological role of PRAME remains elusive. Interestingly, PRAME expression is correlated with a favorable prognosis in childhood acute leukaemias. Moreover, a high expression of PRAME seems to be predominantly found in acute leukaemias carrying a favorable prognosis. In this study, we confirmed in a series of 26 pediatric acute myelogenous leukaemia patients that PRAME expression is associated with an increased disease-free survival. Upon these clinical observations, we assumed that PRAME could be involved in the regulation of cell death or cell cycle. We observed that transient overexpression of PRAME induced a caspase-independent cell death in cultured cell lines (CHO-K1 and HeLa). Cells stably transfected with PRAME also exhibited a decreased proliferation rate due, at least partially, to an elevated basal rate of cell death. Immunocytochemistry of a FLAG-tagged PRAME, in vivo imaging of an EGFP-tagged PRAME and Western blotting after cell fractionation revealed a nuclear localization of the protein. Using a micro-array based approach, we showed that KG-1 leukaemic cells stably transfected with PRAME presented a significant decrease of expression of the heat-shock protein Hsp27, the cyclin dependent kinase inhibitor p21 and the calcium-binding protein S100A4. Moreover, PRAME-positive leukaemic bone marrow samples expressed lower amounts of Hsp27, p21 and S100A4 than PRAME-negative samples. The expression of those three proteins is known to inhibit apoptosis and has been associated with an unfavorable prognosis in a series of cancers. Finally, repression of PRAME expression by a siRNA strategy increased tumorigenicity of K562 leukaemic cells in nude mice. We suggest that the favorable prognosis of PRAME could be mediated, at least in part, by the repression of these genes.Thèse de doctorat en sciences biomédicales (SBIM 3) (orientation : physiologie cellulaire) -- UCL, 200

Neurosciences

Richement illustré et particulièrement pédagogique, cet ouvrage, un classique du domaine, accompagné de ses compléments en ligne est la référence en neurosciences pour tout étudiant en psychologie et sciences cognitives, médecine et biologie

TRPC1 protein channel is major regulator of epidermal growth factor receptor signaling.

TRP channels have been associated with cell proliferation and aggressiveness in several cancers. In particular, TRPC1 regulates cell proliferation and motility, two processes underlying cancer progression. We and others have described the mechanisms of TRPC1-dependent cell migration. However, the involvement of TRPC1 in cell proliferation remains unexplained. In this study, we show that siRNA-mediated TRPC1 depletion in non small cell lung carcinoma cell lines induced G(0)/G(1) cell cycle arrest resulting in dramatic decrease in cell growth. The expression of cyclins D1 and D3 was reduced after TRPC1 knockdown, pointing out the role of TRPC1 in G(1)/S transition. This was associated with a decreased phosphorylation and activation of EGFR and with a subsequent disruption of PI3K/Akt and MAPK downstream pathways. Stimulation of EGFR by its natural ligand, EGF, induced Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry through TRPC1. Ca(2+) entry through TRPC1 conversely activated EGFR, suggesting that TRPC1 is a component of a Ca(2+)-dependent amplification of EGF-dependent cell proliferation

Neurosciences

Richement illustré et particulièrement pédagogique, cet ouvrage, un classique du domaine, accompagné de ses compléments en ligne est la référence en neurosciences pour tout étudiant en psychologie et sciences cognitives, médecine et biologie