A potentially functional polymorphism in ABCG2 predicts clinical outcome of non-small cell lung cancer in a Chinese population

Factors Influencing Mortality in Children with Central Nervous System Tumors: A Cohort Study on Clinical Characteristics and Genetic Markers

Multidrug resistance (MDR) commonly leads to cancer treatment failure because cancer cells often expel chemotherapeutic drugs using ATP-binding cassette (ABC) transporters, which reduce drug levels within the cells. This study investigated the clinical characteristics and single nucleotide variant (SNV) in ABCB1, ABCC1, ABCC2, ABCC4, and ABCG2, and their association with mortality in pediatric patients with central nervous system tumors (CNST). Using TaqMan probes, a real-time polymerase chain reaction genotyped 15 SNPs in 111 samples. Patients were followed up until death or the last follow-up day using the Cox proportional hazards model. An association was found between the rs1045642 (ABCB1) in the recessive model (HR = 2.433, 95% CI 1.098-5.392, p = 0.029), and the ICE scheme in the codominant model (HR = 9.810, 95% CI 2.74-35.06, p ≤ 0.001), dominant model (HR = 6.807, 95% CI 2.87-16.103, p ≤ 0.001), and recessive model (HR = 6.903, 95% CI 2.915-16.544, p = 0.038) significantly increased mortality in this cohort of patients. An association was also observed between the variant rs3114020 (ABCG2) and mortality in the codominant model (HR = 5.35, 95% CI 1.83-15.39, p = 0.002) and the dominant model (HR = 4.421, 95% CI 1.747-11.185, p = 0.002). A significant association between the ICE treatment schedule and increased mortality risk in the codominant model (HR = 6.351, 95% CI 1.831-22.02, p = 0.004, HR = 9.571, 95% CI 2.856-32.07, p ≤ 0.001), dominant model (HR = 6.592, 95% CI 2.669-16.280, p ≤ 0.001), and recessive model (HR = 5.798, 95% CI 2.411-13.940, p ≤ 0.001). The genetic variants rs3114020 in the ABCG2 gene and rs1045642 in the ABCB1 gene and the ICE chemotherapy schedule were associated with an increased mortality risk in this cohort of pediatric patients with CNST.

Association of ABCG2 polymorphisms with susceptibility to anti-tuberculosis drug-induced hepatotoxicity in the Chinese population

Background The accumulation of endogenous hepatotoxin protoporphyrin IX (PPIX) in the liver was proposed to be a novel mechanism of anti-tuberculosis drug-induced hepatotoxicity (ATDH). ATP-binding cassette transporter G2 (ABCG2) plays an important role in modulating PPIX concentrations. This study aimed to explore the role of ABCG2 genetic polymorphisms in the risk of ATDH in Chinese patients.Methods A 1:4 matched case-control study was performed among 202 ATDH cases and 808 controls. Conditional logistic regression model was used to estimate the association between genotypes and the risk of ATDH by odds ratios (ORs) with 95% confidence intervals (CIs).Results Male patients with CC genotype of rs2622605 had an increased risk of ATDH (adjusted OR =1.615, 95% CI: 1.119-2.332, P = 0.011). The peak value of alkaline phosphatase was significantly higher in male patients with CC genotype of rs2622605 than in those with TT + TC genotype during antituberculosis treatment (102.0 U/L vs. 98.0 U/L, P = 0.029).Conclusions This is the first attempt to evaluate the association between ABCG2 genetic variants and the risk of ATDH. Based on the 1:4 matched case-control study, the polymorphism at rs2622605 in the ABCG2 gene may be associated with the susceptibility to ATDH in Chinese male patients.

ATP binding cassette transporters and cancer: revisiting their controversial role

The expression of ATP-binding cassette transporter (ABC transporters) has been reported in various tissues such as the lung, liver, kidney, brain and intestine. These proteins account for the efflux of different compounds and metabolites across the membrane, thus decreasing the concentration of the toxic compounds. ABC transporter genes play a vital role in the development of multidrug resistance, which is the main obstacle that hinders the success of chemotherapy. Preclinical and clinical trials have investigated the probability of overcoming drug-associated resistance and substantial toxicities. The focus has been put on several strategies to overcome multidrug resistance. These strategies include the development of modulators that can modulate ABC transporters. This knowledge can be translated for clinical oncology treatment in the future.

ABC transporter superfamily. An updated overview, relevance in cancer multidrug resistance and perspectives with personalized medicine

The ATP binding-cassette superfamily corresponds the mostly transmembrane transporters family found in humans. These proteins actively transport endogenous and exogenous substrates through biological membranes in body tissues, so they have an important role in the regulation of many physiological functions necessary for human homeostasis, as well as in response regulation to several pharmacological substrates. The development of multidrug resistance has become one of the main troubles in conventional chemotherapy in different illnesses including cancer, being the increased efflux of antineoplastic drugs the main reason for this multidrug resistance, with a key role of the ABC superfamily. Likely, the interindividual variability in the pharmacological response among patients is well known, and may be due to intrinsically factors of the disease, genetic and environmental ones. Thus, the understanding of this variability, especially the genetic variability associated with the efficacy and toxicity of drugs, can provide a safer and more effective pharmacological treatment, so ABC genes are considered as important regulators due to their relationship with the reduction in pharmacological response. In this review, updated information about transporters belonging to this superfamily was collected, the possible role of these transporters in cancer, the role of genetic variability in their genes, as well as some therapeutic tools that have been tried to raise against main transporters associated with chemoresistance in cancer.

M3814, a DNA-PK Inhibitor, Modulates ABCG2-Mediated Multidrug Resistance in Lung Cancer Cells

M3814, also known as nedisertib, is a potent and selective DNA-dependent protein kinase (DNA-PK) inhibitor under phase 2 clinical trials. ABCG2 is a member of the ATP-binding cassette (ABC) transporter family that is closely related to multidrug resistance (MDR) in cancer treatment. In this study, we demonstrated that M3814 can modulate the function of ABCG2 and overcome ABCG2-mediated MDR. Mechanistic studies showed that M3814 can attenuate the efflux activity of ABCG2 transporter, leading to increased ABCG2 substrate drugs accumulation. Furthermore, M3814 can stimulate the ABCG2 ATPase activity in a concentration-dependent manner without affecting the ABCG2 protein expression or cell surface localization of ABCG2. Moreover, the molecular docking analysis indicated a high affinity between M3814 and ABCG2 transporter at the drug-binding cavity. Taken together, our work reveals M3814 as an ABCG2 modulator and provides a potential combination of co-administering M3814 with ABCG2 substrate-drugs to overcome MDR.

Adipose-derived stem cells undergo differentiation after co-culture with porcine limbal epithelial stem cells

Mesenchymal stem cells (MSCs) are objects of interest in regenerative medicine. They are used for various therapies such as for the regeneration of bone, chondrocytes and other tissues. Adipose derived stem cells (ADSCs) inter alia are particularly easy to access, they are relatively abundant in fat tissue. ADSCs could be differentiated into many types of cells. To date, it has been proven that ADSCs only differentiate into mesodermal cell lineages. In this study, we present the differentiation of ADSCs into the corneal epithelium. Human ADSCs were placed in a co-culture with porcine limbal epithelial stem cells (LESCs). After 14 days of cultivation, total RNA was extracted for the analysis of the molecular markers (expression of genes of interest). The gene expression was assessed by real-time RT-qPCR. The expression of the surface molecular markers of ADSCs is modulated after co-culturing. We have observed the decrease in CD73, CD90 and CD105 mRNA expression, while the expression of mRNA coding for CK3 and CK12 mRNA was increased in ADSCs co-cultured with porcine limbal epithelial stem cells as compared to the control. We conclude that the co-culture of LESCs and ADSCs changed ADSCs' molecular markers gene expression indicating initiation of differentiation towards limbal cells.

High frequency of CYP2D6 ultrarapid metabolizers in Spain: controversy about their misclassification in worldwide population studies

A high frequency (7-10%) of CYP2D6 ultrarapid metabolizers estimated from the genotype (gUMs) has been claimed to exist among Spaniards and Southern Europeans. However, methodological aspects such as the inclusion of individuals carrying non-active multiplied alleles as gUMs may have led to an overestimation. Thus, this study aimed to analyze the gUM frequency (considering only those carrying more than two active genes) in 805 Spanish healthy volunteers studied for CYP2D6*2, *3, *4, *5, *6, *10, *17, *35, *41, and multiplications. Second, all worldwide studies reporting gUM frequencies were reviewed in order to evaluate potential misclassifications. The gUM frequency in this Spanish population was 5.34%, but increased to 8.3% if all individuals with CYP2D6 multiplications were classified as gUMs without considering the activity of the multiplied alleles. Moreover, among all reviewed worldwide studies only 55.6% precisely determined whether the multiplied alleles were active. Present results suggest that the evaluation of CYP2D6 ultrarapid metabolism should be standarized, and that the frequency of gUMs should be reconsidered in Spaniards and globally.