ABSTRACT
Although anthracycline-based chemotherapy is a crucial treatment for breast cancer, its outcome is limited by the multidrug resistance MDR. Overexpression of P-glycoprotein [Pgp] a transmembrane active efflux transporter of various drugs and carcinogenic substrate, may result in MDR. The impact of MDR1 polymorphisms on MDR1 expression and risk of breast cancer, and whether it can alter chemotherapeutic agents response in breast cancer is unclear. The present work studied the relevance between MDR1 C3435T, C1236T, G2677T/A polymorphisms and MDR1 gene expression and susceptibility to breast carcinoma as well as sensitivity to anthracyine-based chemotherapy in Egyptian females with breast cancer [BC]. We determined mRNA levels of MDR1 in breast tumor specimens [n=190] by real-time rt-PCR. Blood samples from BC female patients and healthy controls were obtained for genotyping. ARMS-PCR assay was used for detection of C3435T, C1236T and G2677T/A Polymorphisms. This study revealed that C3435 TT patients showed a significant decrease in MDR1 mRNA level compared -with CC genotypes. No association was found between the MDR1 C1236T, G2677T/A polymorphisms and MDR1 mRNA expression. The frequency of C3435 TT genotype and T allele were significantlyhigher in BC patients compared to the controls [P < 0.05]. C3435 TT and C3435 CT had odds ratio [p-value] 5.6 [0.001] and 2.28 [0.01] for response to anthracycline-based chemotherapy, respectively, compared to CC genotype. No statistically significant differences were observed between patients and control regarding the allelic and genotypic frequencies of MDR1 C1236T, G2677T/A polymorphisms as well as no correlation was detected to the response rate to anthracycline-based chemotherapy. Our results suggested that C3435T, but not C1236T or G2677T/A, was associated with changes in MDR1 gene expression and hence alters the response after anthracyclin based chemotherapy
Subject(s)
Humans , Female , Polymorphism, Genetic , Gene Expression , Breast NeoplasmsABSTRACT
Multidrug-resistant tuberculosis [MDR-TB] is an emerging problem with high mortality rate where recently developed molecular techniques represent potential tools for its early detection. The aim of this study is to detect drug resisting mutants of Mycobacterium tuberculosis [M.TB] in 15 patients with active pulmonary tuberculosis, who were non responding to 1[st] line multi-drug therapy [refampicin [ RIF] and isoniazid [INH]]. This was performed using the Chain Termination method of manual Gene Sequencing for the following Mycobacterial genes: rpoB gene [involved in sensitivity to RIF], katG and inhA genes [involved in sensitivity to INH]. Missence point mutations in rpoB gene were found in 93.3 % [14/15], which involved codon 184 in 80% [12/15] with Histidine-Tyrosine substitution, and codon 174 in only 13 .3% [2/15] with Aspartate-Valine substitution. Missence mutations in katG gene were detected in all cases [100%], which involved codon 315 in 80% [12/15] with Serine- Threonine substitution and codon 444 in 13.3 % [2/15] with Valine - Alanine substitution, while only 6.7 %[1/15] involved codon 315 and 444 together. Inh-A gene revealed missence mutantion in 86.7% [13/15], where 60 % [9/15] involved codon 94 with Serine - Valine substitution, 20 %[3/15] involved codon 99 with proline - Arginine substitution and 6.7% [1/15] involved codon 69 with Glutamate - Alanine substitution. It could be concluded that, missence point mutations found in the examined genes could explain the resistance of 14 patients to both drugs and resistance of only one patient to INH alone. The missence point mutation was found at a common codon position among each gene, in addition to some other involved codons. It could be also concluded that, manual gene sequencing is a rapid, non expensive and accurate technique for early detection of MDR-TB, which helps early starting of proper treatment and inhibits spreading of such strains. Although it is difficult to be performed as a routine test, facilities should be available in order to perform it for at least some selected cases, as it does not need the expensive automated DNA sequencer