Toxicity evaluation of synthetic glucocorticoids against breast cancer cell lines MDA-MB-231, MCF-7 and human embryonic kidney HEK293.

In this study, we conducted a comprehensive assessment of the cytotoxicity of three glucocorticoids, namely Hydrocortisone, Dexamethasone, and Methylprednisolone, using three different human cell lines: MDA-MB-231, MCF-7 (both adenocarcinoma cell lines), and HEK293 (kidney epithelial cell line). At lower concentrations exceeding 50 µM, we did not observe any significant toxic effects of these glucocorticoids. However, when exposed to higher concentrations, Hydrocortisone exhibited dose-dependent cytotoxic effects on all three cell lines, with calculated IC50 values of 12 ± 0.6 mM for HEK293, 2.11 ± 0.05 mM for MDA-MB-231, and 2.73 ± 0.128 mM for MCF-7 cells after 48 h of exposure. Notably, Hydrocortisone, at its respective IC50 concentrations, demonstrated an inhibitory effect on the proliferation of the cancer cell lines, as evidenced by a substantial reduction in BrdU absorbance in a dose-dependent manner, coupled with a markedly reduced rate of colony formation in treated cells. Furthermore, Hydrocortisone exhibited remarkable anti-migratory properties in MDA-MB-231 and MCF-7 cells, and it induced cell cycle arrest in the SubG1 phase in MDA-MB-231 cells. In addition to these effects, Hydrocortisone triggered apoptosis in both cancer cell types, leading to observable morphological changes. This apoptotic response was characterized by a significant increase in the activity of caspase-3, which was time-dependent. Additionally, Hydrocortisone downregulated the expression of anti-apoptotic Bcl-2 proteins. In summary, our findings underscore the safety of clinical doses in terms of cell toxicity meanwhile increased concentration were showing an anti-proliferative potential of Hydrocortisone, particularly against adenocarcinoma breast cancer cell lines.

Chemical alternative for cell identification and cross-contamination detection.

Misidentification of human cell lines has previously led to confusing results during cell culture experiments. Although several enzymatic as well as molecular analysis approaches have been developed for cell-line authentication, these methods remain costly. In the present paper, we describe a simple chemical alternative based on known compound cell cytotoxicity. In addition to cisplatin, a pool of eight tamoxifen derivative compounds was used to compare the cytotoxic effects on three different breast cancer cell lines: MCF-7, T47D and MDA-MB-231. Our results show that four out of the eight cytotoxic-related compounds allowed to distinguish the different cell lines based on their IC50 (the half maximal inhibitory concentration) values which are cell type dependent. The remaining chemicals, particularly the most cytotoxic P15, showed close IC50 values for all the cell lines. Interestingly, flow cytometry experiments have identified notable differences among the three cell lines treated with P15. T47D and MDA-MB231 cells were blocked in SubG1 phase and S phase, respectively, while no significant change in cell cycle profile was noticed for MCF-7 cells. Differences were also noted at the level of caspase-3 activity and cell proliferation in P15-treated cells.

Controversial effect on Erk activation of some cytotoxic drugs in human LOVO colon cancer cells.

UNLABELLED: The use of some classic antibiotics was recently shown to inhibit growth and to induce apoptosis in human LOVO colon cancer cells. In this study, we describe that ciprofloxacin (CI), trimebutine maleate (COL) and tiemonium methylsulfate (VIS) greatly inhibit cell proliferation in vitro. Proliferation inhibition reached its maximum at 10(-4 )M, 10(-3 )M and 10(-2 )M, respectively, for COL, CI and VIS. Moreover, phospho-extracellular-regulated kinase was totally abrogated in non-apoptotic cytotoxicity of VIS but decreases or increases in the apoptotic inhibition, respectively, of COL and CI treatments. ABBREVIATIONS: CI: ciprofloxacin; COL: trimebutine maleate; VIS: tiemonium methylsulfate; MAPK/Erk: mitogen-activated protein kinases/extracellular-regulated kinase.

Effect of estradiol and clomiphene citrate on Erk activation in breast cancer cells.

The mitogen-activated protein kinase (MAPK) signaling pathway plays key roles in the transmission of proliferative signals in normal and dysregulated cells. Nevertheless, some studies have shown that activation of the extracellular regulated kinases 1/2 (Erk1/2) is involved in apoptosis. In this study, we evaluate the effect of two fertilizing drugs, clomiphene citrate and estradiol, on the activation of Erk1/2 and the viability of two breast cancer cell lines, MCF-7 (hormone dependent) and BT20 (hormone independent).We show that both drugs induce Erk1/2 phosphorylation in MCF-7 and BT20 cells despite their opposite effect on cell viability. In fact, clomiphene citrate is significantly proapoptotic while estradiol promotes cell proliferation. The fact that phospho-Erk1/2 is a common element to both mechanisms suggests that specific factors deciding between proliferation and apoptosis must be operative downstream of this signaling pathway.

A novel missense mutation in the ESRRB gene causes DFNB35 hearing loss in a Tunisian family.

Autosomal recessive non-syndromic hearing loss (ARNSHL) is a genetically heterogenous disorder with 41 genes so far identified. Among these genes, ESRRB whose mutations are responsible for DFNB35 hearing loss in Pakistani and Turkish families. This gene encodes the estrogen-related receptor beta. In this study, we report a novel mutation (p.Y305H) in the ESRRB gene in a Tunisian family with ARNSHL. This mutation was not detected in 100 healthy individuals. Molecular modeling showed that the p.Y305H mutation is likely to alter the conformation of the ligand binding-site by destabilizing the coactivator binding pocket. Interestingly, this ligand-binding domain of the ESRRB protein has been affected in 5 out of 6 mutations causing DFNB35 hearing loss. Using linkage and DHPLC analysis, no more mutations were detected in the ESRRB gene in other 127 Tunisian families with ARNSHL indicating that DFNB35 is most likely to be a rare type of ARNSHL in the Tunisian population.

DFNB66 and DFNB67 loci are non allelic and rarely contribute to autosomal recessive nonsyndromic hearing loss.

We previously mapped the DFNB66 locus to an interval overlapping the DFNB67 region. Mutations in the LHFPL5 gene were identified as a cause of DFNB67 hearing loss (HL). However, screening of the coding exons of LHFPL5 did not reveal any mutation in the DFNB66 family. The objective of this study was to check whether DFNB66 and DFNB67 are distinctive loci and determining their contribution to HL. In the DFNB66 family, sequencing showed absence of mutations in the untranslated regions and the predicted promoter sequence of LHFPL5. Analysis of five microsatellites in the 6p21.31-22.3 region and screening of the LHFPL5 gene by DNA heteroduplex analysis in DHPLC revealed a novel mutation (c.89dup) in one out of 129 unrelated Tunisian families with autosomal recessive nonsyndromic (ARNS) HL. Our findings suggest that two distinct genes are responsible for DFNB66 and DFNB67 HL. These loci are likely to be a rare cause of ARNSHL.

Association of COL1A1 and TGFB1 polymorphisms with otosclerosis in a Tunisian population.

Otosclerosis is a condition characterized by an abnormal bone metabolism in the otic capsule, resulting in conductive and/or sensorineural hearing loss. Otosclerosis is a common disorder in which genes play an important role. Case-control association studies have implicated several genes in the abnormal bone metabolism associated with otosclerosis: COL1A1, TGFB1, BMP2, and BMP4. To investigate the association of these genes with otosclerosis in the Tunisian population, we examined nine single nucleotide polymorphisms (SNPs) in 159 unrelated otosclerosis patients and 155 unrelated controls. We found an association of rs11327935 in COL1A1 with otosclerosis that was shown to be sex specific. The coding polymorphism T263I in TGFB1 was also associated with otosclerosis in the Tunisian population. The effect sizes of both the associations were consistent with previous studies, as the same effect was found in all cases. The association of BMP2 and BMP4 was not significant. However, a trend towards association was found for the BMP4 gene that was consistent with earlier reports. In conclusion, this study replicates and strengthens the evidence for association between polymorphisms of COL1A1 and TGFB1 in the genetic aetiology of otosclerosis.

A novel dominant mutation in SIX1, affecting a highly conserved residue, result in only auditory defects in humans.

Branchio-oto-renal (BOR) and Branchio-otic (BO) syndromes are dominant disorders characterized by variable hearing impairment (HI) and branchial defects. BOR includes additional kidney malformations. BO/BOR syndromes are genetically heterogeneous and caused by mutations in EYA1 and SIX1 genes. Mutation in SIX1 is responsible also for DFNA23, a locus for non-syndromic HI. Strikingly, the severity of the phenotype did not seem to correlate with the type of SIX1 mutation. Herein, we identified a novel mutation in SIX1 (p.E125K) in a Tunisian family with variable HI and preauricular pits. This mutation is located at the same position as the mutation identified in the Catwhesel (Cwe) mouse. No renal and branchial defects were observed in our family nor in Cwe/+ mice. A homology model revealed that the replacement of the Glutamate by a Lysine alters the electrostatic potential surface propriety which may affect the DNA-binding activity.

Alteration of the serine protease PRSS56 causes angle-closure glaucoma in mice and posterior microphthalmia in humans and mice.

Angle-closure glaucoma (ACG) is a subset of glaucoma affecting 16 million people. Although 4 million people are bilaterally blind from ACG, the causative molecular mechanisms of ACG remain to be defined. High intraocular pressure induces glaucoma in ACG. High intraocular pressure traditionally was suggested to result from the iris blocking or closing the angle of the eye, thereby limiting aqueous humor drainage. Eyes from individuals with ACG often have a modestly decreased axial length, shallow anterior chamber and relatively large lens, features that predispose to angle closure. Here we show that genetic alteration of a previously unidentified serine protease (PRSS56) alters axial length and causes a mouse phenotype resembling ACG. Mutations affecting this protease also cause a severe decrease of axial length in individuals with posterior microphthalmia. Together, these data suggest that alterations of this serine protease may contribute to a spectrum of human ocular conditions including reduced ocular size and ACG.

Identification of candidate regions for a novel Usher syndrome type II locus.

PURPOSE: Chronic diseases affecting the inner ear and the retina cause severe impairments to our communication systems. In more than half of the cases, Usher syndrome (USH) is the origin of these double defects. Patients with USH type II (USH2) have retinitis pigmentosa (RP) that develops during puberty, moderate to severe hearing impairment with downsloping pure-tone audiogram, and normal vestibular function. Four loci and three genes are known for USH2. In this study, we proposed to localize the gene responsible for USH2 in a consanguineous family of Tunisian origin. METHODS: Affected members underwent detailed ocular and audiologic characterization. One Tunisian family with USH2 and 45 healthy controls unrelated to the family were recruited. Two affected and six unaffected family members attended our study. DNA samples of eight family members were genotyped with polymorphic markers. Two-point and multipoint LOD scores were calculated using Genehunter software v2.1. Sequencing was used to investigate candidate genes. RESULTS: Haplotype analysis showed no significant linkage to any known USH gene or locus. A genome-wide screen, using microsatellite markers, was performed, allowing the identification of three homozygous regions in chromosomes 2, 4, and 15. We further confirmed and refined these three regions using microsatellite and single-nucleotide polymorphisms. With recessive mode of inheritance, the highest multipoint LOD score of 1.765 was identified for the candidate regions on chromosomes 4 and 15. The chromosome 15 locus is large (55 Mb), underscoring the limited number of meioses in the consanguineous pedigree. Moreover, the linked, homozygous chromosome 15q alleles, unlike those of the chromosome 2 and 4 loci, are infrequent in the local population. Thus, the data strongly suggest that the novel locus for USH2 is likely to reside on 15q. CONCLUSIONS: Our data provide a basis for the localization and the identification of a novel gene implicated in USH2, most likely localized on 15q.