Down-modulation of SEL1L, an unfolded protein response and endoplasmic reticulum-associated degradation protein, sensitizes glioma stem cells to the cytotoxic effect of valproic acid

Valproic acid (VPA), an histone deacetylase inhibitor, is emerging as a promising therapeutic agent for the treatments of gliomas by virtue of its ability to reactivate the expression of epigenetically silenced genes. VPA induces the unfolded protein response (UPR), an adaptive pathway displaying a dichotomic yin yang characteristic; it initially contributes in safeguarding the malignant cell survival, whereas long-lasting activation favors a proapoptotic response. By triggering UPR, VPA might tip the balance between cellular adaptation and programmed cell death via the deregulation of protein homeostasis and induction of proteotoxicity. Here we aimed to investigate the impact of proteostasis on glioma stem cells (GSC) using VPA treatment combined with subversion of SEL1L, a crucial protein involved in homeostatic pathways, cancer aggressiveness, and stem cell state maintenance. We investigated the global expression of GSC lines untreated and treated with VPA, SEL1L interference, and GSC line response to VPA treatment by analyzing cell viability via MTT assay, neurosphere formation, and endoplasmic reticulum stress/UPR-responsive proteins. Moreover, SEL1L immunohistochemistry was performed on primary glial tumors. The results show that (i) VPA affects GSC lines viability and anchorage-dependent growth by inducing differentiative programs and cell cycle progression, (ii) SEL1L down-modulation synergy enhances VPA cytotoxic effects by influencing GSCs proliferation and self-renewal properties, and (iii) SEL1L expression is indicative of glioma proliferation rate, malignancy, and endoplasmic reticulum stress statuses. Targeting the proteostasis network in association to VPA treatment may provide an alternative approach to deplete GSC and improve glioma treatments.

Influence of sex on cytogenetic end points: evidence from a large human sample and review of the literature

The planning and evaluation of human cytogenetic studies should contemplate various confounders and effect modifiers, among these, sex and sex-related factors. The association between this variable and cytogenetic damage has been extensively studied, but conclusive evidence has thus far not been reached, especially for the most recent assays, such as the micronucleus test (MN). In the attempt to quantitatively estimate the sex effect on sister chromatid exchange (SCE), chromosomal aberration (CA), and MN in peripheral blood lymphocytes, we reanalyzed the original data sets of several biomonitoring studies performed over the last decades in 10 Italian laboratories. This approach yielded a very large database, namely 2140, 2495, and 2131 subjects screened for SCE, CA, and MN, respectively. Differences between sexes were expressed in terms of relative risk (RR) of females versus males, after adjustment for age, smoking habits, occupation exposure and inter- and intralaboratory variation. No difference between sexes was found for the frequency of SCE [RR = 1.01; 95% confidence interval (CI) = 0.99-1.03] and CA (RR = 1.00; 95% CI = 0.92-1.08) even if the CI of the RR for SCE includes the 3% excess in females frequently reported by the literature. Conversely, a 29% overall increase of the MN rate in females was observed in the whole data set (RR = 1.29; 95% CI = 1.20-1.38). Different trends by age of the MN rate are described in the two sexes, focusing on the peak observed in females in the menopausal period and on the subsequent decrease.

The phenotype of partial dup(7q) reconsidered: a report of five new cases

Five unrelated patients with partial trisomy 7q are described. In two of them the duplicated region was 7q21----qter and in the others 7q22----qter, 7q34----qter and 7q35----qter, respectively. Clinical features were compared with those reported in published cases. Karyotype-phenotype correlations showed a relationship between the size of the unbalanced region and the survival, and prenatal and postnatal growth. In contrast, the same proportionality was not demonstrated between the severity of dysmorphic features and the size of the duplicated region. However, cleft palate seemed associated rather characteristically with dup 7q22/31----qter.

47,XXX chromosome constitution in a male

An 18-year-old boy with a male phenotype was examined because of testicular hypoplasia. Chromosome analysis using Q- and R-banding techniques and BUdR treatment showed a 47,XXX karotype, in both lymphocytes and fibroblasts. Cytogenetic problems raised by this case are discussed in relation to data from previous published reports.

Incorporation of (3H)thymidine stimulated by ultraviolet radiation into human fibroblast cultures

We studied DNA repair synthesis after ultraviolet irradiation in human fibroblasts cultured in vitro by measuring the ultraviolet-stimulated incorporation of [3H]thymidine into cells in which the semi-conservative DNA replication was inhibited by hydroxyurea. Experiments performed with five fibroblasts lines derived from healthy donors showed a relatively fast initial process ( that is completed within 1 h for 100 erg/mm2 and within 2 h for 500 erg/mm2) and a subsequent slower process, evident between 2 and 6 h after irradiation. The repair capacity of normal cells is expressed by the difference between the values of incorporation (in presence of hydroxyurea) of irradiated and control cells. The pattern of repair was similar in all five cell lines: repair capacity was positive and the amount of repair synthesis increased with incubation time after UV irratiation. Similar experiments were performed with fibroblasts derived from five patients with the classical xeroderma pigmentosum (XP) and from one patient with the De Sanctis-Cacchione syndrome. Normal and XP cells could be distinguished according to whether they displayed a positive or negative value of repair synthesis and/or according to the degree of the slope of the repair synthesis curve as a function of the incubation time after irradiation. We conclude that the technique used in our experiments can demonstrate in a rapid and simple way a defect in the repair capacity in fibroblast cultures; the data are in good agreement with those obtained in the same XP cell lines by other authors [9], who have measured unscheduled DNA synthesis in autoradiographs and repair replication after addition of BUdR.

Evidence for two waves of induction of DNA enzymes in stimulated human lymphocytes

The stimulation of human lymphocytes with phytohaemoagglutinin induces the appearance or increase of several enzymes of DNA metabolism [Pedrini etal., Biochem. Biophys. Res. Comm., 47:1221(1972)]. With long times of stimulation, two phenomena are observed; an increase in the levels of DNA polymerase, of a DNase acting on single-stranded DNA, and of an endonuclease, occurring between the third and fourth day, in parallel with a wave of DNA synthesis;a second wave of increase of the same enzymes and of DNA ligase,occurring between the fifth and eight day when the DNA replication rate, as measured by thymidine-pulses, has decreased to values close to the background.

Levels of some enzymes acting on DNA in xeroderma pigmentosum

We have determined the levels of DNA polymerase, DNA ligase, a DNase acting on single-stranded DNA, an endonuclease making single-strand breaks in double - stranded DNA and polynucleotide kinase in fibroblasts obtained from nine normal persons and from nine patients with Xeroderma Pigmentosum; the pathological lines belong to the different described clinical forms and to the three different complementation groups described so far. All the enzymes are present in the normal lines and in the Xeroderma lines. The levels are quite variable, but the values obtained in the pathological lines lie within the ones observed in the normal population.