Amjad Mahasneh

Mitochondrial copy number and risk of breast cancer: a pilot study.

It has been proposed that the copy number of mitochondria DNA (mtDNA) per cell reflects gene-environment interactions between unknown hereditary factors and exposures affecting levels of oxidative stress. However, whether copy number of mtDNA could be a risk predictor of oxidative stress-related human cancers, such as breast cancer, remains to be determined. To explore the role of mtDNA copy number in breast cancer etiology, we analyzed mtDNA copy number in whole blood from 103 patients with breast cancer and 103 matched control subjects and examined in relation to endogenous antioxidants. Case patients with breast cancer had a statistically significantly higher mtDNA copy number than control subjects (median: 1.29 vs. 0.80, P<0.01). High mtDNA copy number (above the median in controls) was associated with a statistically significantly increased risk of breast cancer, compared with low copy number (Odds ratio (OR)=4.67, 95% CI: 2.45-8.92), with a statistically significant dose-response relationship in trend analysis (P<0.01). Moreover, mtDNA copy number was significantly inversely associated with several important endogenous oxidants and antioxidants in blood in either the cases (total glutathione, CuZn-SOD activity and myeloperoxidase (MPO)) or the controls (catalase (CAT) activity). These results suggest the mtDNA copy number could be associated with risk of breast cancer, perhaps through an oxidative stress mechanism.

Regulation of the p21-activated Kinase-relatedDictyostelium Myosin I Heavy Chain Kinase by Autophosphorylation, Acidic Phospholipids, and Ca2+-Calmodulin

The Dictyostelium myosin I heavy chain kinase (MIHCK) is a member of the p21-activated kinase family (Lee, S.-F., Egelhoff, T. T., Mahasneh, A., and Côté, G. P. (1996) J. Biol. Chem. 271, 27044–27048). MIHCK incubated with MgATP in the absence of effectors incorporates 1 mol of phosphate/mol, resulting in an ∼40-fold increase in kinase activity. Sequence analysis of tryptic peptides has identified the major site of phosphorylation as Ser-8. A peptide and a glutathioneS-transferase fusion protein containing the Ser-8 phosphorylation site were good substrates for MIHCK, indicating that MIHCK can catalyze its own activation. Guanosine 5′-3-O-(thio)triphosphate (GTPγS)-Rac1 stimulates MIHCK autophosphorylation and kinase activity 10-fold. Phosphatidylserine, phosphatidylinositol, and phosphatidylinositol 4,5-bisphosphate, but not phosphatidylcholine or sphingosine, were as effective as GTPγS-Rac1 in enhancing MIHCK autophosphorylation and activity. Acidic lipids and GTPγS-Rac1 induced the autophosphorylation of a similar set of sites as judged by two-dimensional tryptic peptide maps. It is proposed that GTP-Rac and acidic phospholipids function cooperatively to associate MIHCK with membranes. Ca2+-calmodulin bound MIHCK and inhibited activation by acidic phospholipids but not by GTPγS-Rac1. These studies reveal a number of similarities between the regulatory properties of the Dictyostelium andAcanthamoeba MIHCK, suggesting that the signaling pathways that control myosin I are conserved.

Molecular biomarkers for an early diagnosis, effective treatment and prognosis of colorectal cancer: Current updates

Colorectal cancer (CRC) is the third most prevalent cancer in the world. Globally, it has been estimated that about 1.4 million new cases of colorectal cancer are diagnosed every year. CRC is a multifactorial disease that arises due to genetics as well as epigenetic alterations in a number of oncogenes, tumor suppressor genes, mismatch repair genes, as well as cell cycle regulating genes in colon mucosal cells. These molecular alterations have been considered as potential CRC biomarkers because they can provide the physicians with diagnostic, prognostic and treatment response information. The goal is to identify relevant, cheap and applicable biomarkers that contribute to patient management decisions, resulting in direct benefits to patients. In this review, we will outline the most currently available and developing tumor tools, and blood molecular biomarkers. Also, we will illustrate their diagnostic, therapeutic and prognostic applications.

Novel sequence variants in the TMIE gene in families with autosomal recessive nonsyndromic hearing impairment

To date, 37 genes have been identified for nonsyndromic hearing impairment (NSHI). Identifying the functional sequence variants within these genes and knowing their population-specific frequencies is of public health value, in particular for genetic screening for NSHI. To determine putatively functional sequence variants in the transmembrane inner ear (TMIE) gene in Pakistani and Jordanian families with autosomal recessive (AR) NSHI, four Jordanian and 168 Pakistani families with ARNSHI that is not due to GJB2 (CX26) were submitted to a genome scan. Two-point and multipoint parametric linkage analyses were performed, and families with logarithmic odds (LOD) scores of 1.0 or greater within the TMIE region underwent further DNA sequencing. The evolutionary conservation and location in predicted protein domains of amino acid residues where sequence variants occurred were studied to elucidate the possible effects of these sequence variants on function. Of seven families that were screened for TMIE, putatively functional sequence variants were found to segregate with hearing impairment in four families but were not seen in not less than 110 ethnically matched control chromosomes. The previously reported c.241C>T (p.R81C) variant was observed in two Pakistani families. Two novel variants, c.92A>G (p.E31G) and the splice site mutation c.212 −2A>C, were identified in one Pakistani and one Jordanian family, respectively. The c.92A>G (p.E31G) variant occurred at a residue that is conserved in the mouse and is predicted to be extracellular. Conservation and potential functionality of previously published mutations were also examined. The prevalence of functional TMIE variants in Pakistani families is 1.7% [95% confidence interval (CI) 0.3–4.8]. Further studies on the spectrum, prevalence rates, and functional effect of sequence variants in the TMIE gene in other populations should demonstrate the true importance of this gene as a cause of hearing impairment.

Screening of GJB6 Gene for the 342-kb Deletion in Patients from Jordan with Non Syndromic Hearing Loss

Abstract Hearing loss is a common congenital disorder frequently associated with mutations in the connexin 26 gene (GJB2). However, recent studies found a 342-kb deletion in another gene, connexin 30 (GJB6) that causes nonsyndromic recessive hearing loss in either a homozygous monogenic inheritance of Cx30 deletion or digenic inheritance of Cx30 deletion and a Cx26 mutation. The objective of this study was to screen for the 342-kb deletion in Cx30 gene in patients with non-syndromic hearing loss from Jordan. Two different PCR conditions were used to detect the 342- kb deletion of connexin 30 gene by amplifying the deletion breakpoints using specific primers. None of the patients with non-syndromic hearing loss was found to carry deletion in connexin 30 gene indicating that the occurrence of this deletion is restricted to Spanish, Caucasians, and Ashkenazi Jews.

Prevalence of Connexin 26 Mutations in Patients from Jordan with Non Syndromic Hearing Loss

Abstract Mutations in GJB2 gene are a major cause of autosomal recessive congenital hearing loss and the cause in some rare cases of the autosomal dominant form. The objectives of this study were to estimate the frequency of connexin 26 35delG and 167delT mutations in congenital deaf Jordanian population and to estimate the frequency of carriers among normal Jordanian population. PCR was used to amplify two regions of the exon 2 of connexin26 and PCR products were analyzed using BslI and PstI analysis followed by gel electrophoresis. Homozygous 35delG was detected in fourteen out of 114 (12.3%) of the familial group, while in the sporadic group there was one individual out of 38 (2.6%). There were five individuals with a heterozygous mutations (35delG+ /unknown), three of them were in the familial group (2.6%) and two in the sporadic group (5.3%). Among the normal group there was one carrier sample out of 95 (1.1%). The 167delT mutation was not detected in any of the deaf individuals, while it was detected in one individual from the normal group. The allele frequency for the 35delG mutation among the familial group was 13.6 % and 5.3 % for the sporadic group. The frequency of carriers among normal individuals was 1.1%. For the 167delT mutation the allele frequency was zero for the familial and sporadic groups.

Polymorphisms of arylamine N-acetyltransferase2 and risk of lung and colorectal cancer

The arylamine N-acetyltransferase 2 (NAT2) enzymes detoxify a wide range of naturally occurring xenobiotics including carcinogens and drugs. Point mutations in the NAT2 gene result in the variant alleles M1 (NAT2 *5A), M2 (NAT2*6A), M3 (NAT2*7) and M4 (NAT2 *14A) from the wild-type WT (NAT2 *4) allele. The current study was aimed at screening genetic polymorphisms of NAT2 gene in 49 lung cancer patients, 54 colorectal cancer patients and 99 cancer-free controls, using PCR-RFLP. There were significant differences in allele frequencies between lung cancer patients and controls in the WT, M2 and M3 alleles (p < 0.05). However, only M2 and M3 allele frequencies were different between colorectal cancer patients and controls (p < 0.05). There was a marginal significant difference in the distribution of rapid and slow acetylator genotypes between lung cancer patients and controls (p = 0.06 and p = 0.05, respectively), but not between colorectal cancer patients and controls (p = 1.0 and p = 0.95, respectively). Risk of lung cancer development was found to be lower in slow acetylators [odds ratio (OR): 0.51, 95% confidence interval (95% CI): 0.25, 1.02, p-value = 0.07]. No effect was observed in case of colorectal cancer. Our results showed that NAT2 genotypes and phenotypes might be involved in lung cancer but not colorectal cancer susceptibility in Jordan.

The association of HLA-DQB1*0602 but not HLA-DRB1*15 with obstructive sleep apnea

PURPOSE Obstructive sleep apnea (OSA) is a sleep breathing disorder with unclear multifactorial pathogenesis. This study aimed to investigate the association between OSA and two human leukocyte antigens (HLA) alleles; DQB1*0602 and DRB1*15. METHODS Forty patients with OSA and 40 control subjects were enrolled in the study. OSA diagnosis was made utilizing the Apnea-Hypopnea Index (AHI)≥5 in overnight polysomnography (PSG). AHI was also used to determine OSA severity. Controls were randomly selected from healthy volunteers who had a low risk for OSA, utilizing the Berlin Questionnaire. Polymerase chain reaction (PCR) using Sequence Specific Primers (PCR-SSPs) was used to determine the association between HLA (HLA-DQB1*0602 and HLA-DRB1*15) and OSA, then statistical analyses of the results were performed. RESULTS HLA-DQB1*0602 allele was found in 85% of all OSA patients and 50% of controls (P< 0.001). In patients with severe OSA, HLA-DQB1*0602 was present in the 92.9% compared with 66.7% in non-severe OSA (P=0.05). HLA-DRB1*15 allele was found in 15% of OSA patients and 20% of controls, with no difference between the two groups (P=0.556). No statistical difference was found in HLA-DRB1*15 between severe and non-severe OSA (P=0.499). After adjusting for gender, HLA-DQB1*0602 allele was associated with increased odds of OSA (OR = 6.17, 95% CI 1.87-20.3, p = 0.003), but HLA-DRB1*15 allele was not associated with OSA (OR 0.45, 95% CI 0.12-1.73, p = 0.242). CONCLUSIONS The presence of HLA-DQB1*0602 allele, but not HLA-DRB1*15 allele, was significantly associated with OSA.