Single nucleotide polymorphisms in the multidrug resistance gene 1 (ABCB1): effects on its expression and clinicopathological characteristics in breast cancer patients. Pharmacogenet Genomics. 2008;18:263-273. [PMID: 18300948 DOI: 10.1097/fpc.0b013e3282f60a91]

GALNT14 in association with GDF-15 promotes stemness and drug resistance through β-catenin signalling pathway in breast cancer

BACKGROUND

Altered glycosylation plays a role in carcinogenesis. GALNT14 promotes cancer stem-like properties and drug resistance. GDF-15 is known to induces drug resistance and stemness markers for maintenance of breast cancer (BC) stem-like cell state. Currently there is lack of data on association of GDF-15 and GALNTs. In this study, the expression and interaction of GALNT14 and GDF-15 with stemness (OCT4 and SOX2) and drug resistance (ABCC5) markers were evaluated in BC.

METHODS

We investigated tumour tissue from 30 BC patients and adjacent non-tumour tissues. Expression of serum GALNT14 from BC patients and matched healthy controls was evaluated. Expression of GALNT14, GDF-15, OCT4, SOX2, ABCC5, and β-catenin in BC tissue was determined by RT-PCR. Knockdown of GALNT14 and GDF-15 in the MCF-7 cell line was done through siRNA, gene expression and protein expression of β-catenin by western blot were determined.

RESULTS

A significant increase in the expression of GALNT14, GDF-15, OCT4, SOX2, ABCC5, and β-catenin was observed in BC tumour tissues compared to adjacent non-tumour tissues. The serum level of GALNT14 was significantly high in BC patients (80.7 ± 65.3 pg/ml) compared to healthy controls (12.2 ± 9.12 pg/ml) (p < 0.000). To further analyse the signalling pathway involved in BC stemness and drug resistance, GALNT14 and GDF-15 were knocked down in the MCF-7 cell line, and it was observed that after knockdown, the expression level of OCT4, SOX2, ABCC5, and β-catenin was decreased, and co-knockdown with GALNT14 and GDF-15 further decreased the expression of genes.

CONCLUSION

It can be concluded that GALNT14, in association with GDF-15, promotes stemness and intrinsic drug resistance in BC, possibly through the β-catenin signalling pathway.

The ABCB1 3435C > T polymorphism influences docetaxel transportation in ovarian cancer

Objective

To investigate the effect of the ATP-binding cassette transporter superfamily B member 1 gene (ABCB1 ) 3435C > T single nucleotide polymorphism (SNP) on docetaxel transportation in ovarian cancer cells.

Methods

ES-2 and SKOV3 cells were transfected with an ABCB1 3435C > T recombinant plasmid, and mRNA expression was detected by real-time PCR. The MTT assay was used to detect the toxicity of docetaxel. High-performance liquid chromatography determined the drug concentration in different cell models to evaluate intracellular accumulation, and a transmembrane resistance experiment was used to assess permeability and evaluate the effect of P-gp activity on drug transportation. A tumor-bearing mouse model was established to evaluate the effect of ABCB1 3435C > T on docetaxel resistance.

Results

P-gp was overexpressed in cells transfected with the ABCB1 3435C > T plasmid, leading to a significant increase in drug resistance to docetaxel. ABCB1 3435C/wild-type transfection significantly promoted the transport of docetaxel mediated by P-gp compared with ABCB1 3435T/mutant transfection.

Conclusion

P-gp encoded by the ABCB1 variant allele appears to be more efficient at transporting docetaxel compared with the wild-type allele. The ABCB1 3435C > T SNP dramatically affected the efflux ability of P-gp against docetaxel, and may influence P-gp expression and activity.

Role of Four ABC Transporter Genes in Pharmacogenetic Susceptibility to Breast Cancer in Jordanian Patients

Breast cancer pharmacogenetics is increasingly being explored due to chemotherapy resistance among certain classes of patients. The ATP binding cassette (ABC) transporter genes have been previously implicated in breast cancer progression and drug response. In the present study, single nucleotide polymorphisms (SNPs) from the ABCC1, ABCC2, ABCB1, and ABCG2 genes were screened in breast cancer patients and healthy volunteers from the Jordanian-Arab population. Only the ABCB1 SNPs showed a significant association with BC in Jordanian-Arab patients, and the ABCB1 SNP rs2032582 exhibited a strong genotypic association with BC. With regard to the clinical characteristics of BC, the ABCC2 SNPs rs2273697 and rs717620 were found to be significantly associated with age at breast cancer diagnosis and breastfeeding status, while the ABCB1 SNP rs1045642 was significantly associated with age at breast cancer diagnosis. In terms of pathological characteristics, the ABCC1 SNP rs35628 and the ABCB1 SNP rs2032582 were significantly associated with tumor size, the ABCC2 SNP rs2273697 was significantly associated with estrogen receptor status, and the ABCG2 SNP rs2231142 was significantly associated with axillary lymph node status. In this current study, we assume that significant genetic variants within the ABC superfamily may increase the risk of breast cancer among Jordanian women. Furthermore, these variants might be responsible for worse BC prognosis.

Methyl-methanesulfonate sensitivity 19 expression is associated with metastasis and chemoradiotherapy response in esophageal cancer

AIM: To investigate the clinical significance of methyl-methanesulfonate sensitivity 19 (MMS19) expression in esophageal squamous cell carcinoma (ESCC).

METHODS: Between June 2008 and May 2013, specimens from 103 patients who underwent endoscopic biopsy for the diagnosis of ESCC at the endoscopy center of Sun Yat-Sen University Cancer Center were collected; 52 matched-normal esophageal squamous epithelium samples were biopsied as controls. MMS19 protein expression was measured by immunohistochemistry. Of the 103 cases of ESCC, 49 received radical surgery following neoadjuvant chemoradiotherapy consisting of concurrent radiation in a total dose of 40 Gy and two cycles of chemotherapy with vinorelbine and cisplatin. Relationships between MMS19 expression, clinicopathologic characteristics and chemoradiotherapy response were analyzed.

RESULTS: The MMS19 protein could be detected in both the cytoplasm and nucleus of most specimens. High cytoplasmic expression of MMS19 was detected in 63.1% of ESCC samples, whereas high nuclear expression of MMS19 was found in 35.0%. High cytoplasmic MMS19 expression was associated with regional lymph node metastases (OR = 11.3, 95%CI: 2.3-54.7; P < 0.001) and distant metastases (OR = 13.1, 95%CI: 1.7-103.0; P = 0.002). Furthermore, high cytoplasmic MMS19 expression was associated with a response of ESCC to chemoradiotherapy (OR = 11.5, 95%CI: 3.0-44.5; P < 0.001), with a high cytoplasmic MMS19 expression rates in 79.3% and 25.0% of patients from the good chemoradiotherapy response group and poor response group, respectively. Nuclear MMS19 expression did not show any significant association with clinicopathologic characteristics or chemoradiotherapy response in ESCC.

CONCLUSION: The results of our preliminary study suggest that MMS19 may be a potential new predictor of metastasis and chemoradiotherapy response in ESCC.

Non-coding polymorphisms in nucleotide binding domain 1 in ABCC1 gene associate with transcript level and survival of patients with breast cancer

OBJECTIVES

ATP-Binding Cassette (ABC) transporters may cause treatment failure by transporting of anticancer drugs outside of the tumor cells. Multidrug resistance-associated protein 1 coded by the ABCC1 gene has recently been suggested as a potential prognostic marker in breast cancer patients. This study aimed to explore tagged haplotype covering nucleotide binding domain 1 of ABCC1 in relation with corresponding transcript levels in tissues and clinical phenotype of breast cancer patients.

METHODS

The distribution of twelve ABCC1 polymorphisms was assessed by direct sequencing in peripheral blood DNA (n = 540).

RESULTS

Tumors from carriers of the wild type genotype in rs35623 or rs35628 exhibited significantly lower levels of ABCC1 transcript than those from carriers of the minor allele (p = 0.003 and p = 0.004, respectively). The ABCC1 transcript levels significantly increased in the order CT-GT>CC-GT>CC-GG for the predicted rs35626-rs4148351 diplotype. Chemotherapy-treated patients carrying the T allele in rs4148353 had longer disease-free survival than those with the GG genotype (p = 0.043). On the other hand, hormonal therapy-treated patients with the AA genotype in rs35628 had significantly longer disease-free survival than carriers of the G allele (p = 0.012).

CONCLUSIONS

Taken together, our study shows that genetic variability in the nucleotide binding domain 1 has a significant impact on the ABCC1 transcript level in the target tissue and may modify survival of breast cancer patients.

Pharmacogenotyping of CYP3A5 in predicting dose-adjusted trough levels of tacrolimus among Malaysian kidney-transplant patients

Tacrolimus (FK506) is a calcineurin inhibitor with a narrow therapeutic index that exhibits large interindividual variation. Seventy-eight kidney transplant patients treated with tacrolimus were recruited to study the correlation of dose adjusted trough level (level/dose; L/D) of tacrolimus with CYP3A5 and ABCB1 genotypes, as well as the mRNA copy number of ABCB1 in blood. Patients were genotyped for ABCB1 (C1236T, G2677T/A, and C3435T) and CYP3A5 (G6986A), while ABCB1 mRNA transcript copy number was determined by absolute quantification (real-time PCR) in 46 patients. CYP3A5*3 genotypes were found to be a good predictor of tacrolimus L/D in kidney-transplant patients. Significantly higher L/D was observed among non-expressors (2.85, 95%: 2.05–3.70 (ng·mL–1)/(mg·kg–1)) as compared with the expressors (1.15, 95%: 0.95–1.80 (ng·mL–1)/(mg·kg–1)) of CYP3A5 (Mann–Whitney U test; P < 0.001). No correlation was observed between L/D and the ABCB1 genotypes. A significant inverse correlation of blood ABCB1 mRNA level with L/D was demonstrated (Spearman’s Rank Order correlation; P = 0.016, rs = –0.348). However, in multiple regression analysis, only CYP3A5*3 genotype groups were found to be significantly correlated with tacrolimus L/D (P < 0.001). These findings highlight the importance of CYP3A5*3 pharmacogenotyping among kidney-transplant patients treated with tacrolimus, and confirm the role of blood cell P-glycoprotein in influencing the L/D for tacrolimus.

The expression profile of ATP-binding cassette transporter genes in breast carcinoma

AIM

ATP-binding cassette (ABC) transporters contribute to development of resistance to anticancer drugs via ATP-dependent drug efflux. A major goal of our study was to investigate associations between the expression of ABC transporters and outcome of breast carcinoma patients.

PATIENTS & METHODS

Transcript levels of all 49 human ABC transporters were determined in post-treatment tumor and non-neoplastic tissue samples from 68 breast carcinoma patients treated by neoadjuvant chemotherapy. Six ABC transporters were then evaluated in independent series of 100 pretreatment patients.

RESULTS

ABCA5/6/8/9/10, ABCB1/5/11, ABCC6/9, ABCD2/4, ABCG5 and ABCG8 were significantly downregulated and ABCA2/3/7/12, ABCB2/3/8/9/10, ABCC1/4/5/10/11/12, ABCD1/3, ABCE1, ABCF1/2/3 and ABCG1 were upregulated in post-treatment tumors compared with non-neoplastic tissues. Significant associations of intratumoral levels of ABCC1 and ABCC8 with grade and expression of hormonal receptors were found in both sets of patients. ABCA12, ABCA13 and ABCD2 levels were significantly associated with the response to neoadjuvant chemotherapy in post-treatment patients. Protein expression of ABCA12, ABCC8 and ABCD2 in tumor tissues of patients with breast carcinoma was observed by immunoblotting for the first time.

CONCLUSION

ABCA12, ABCA13, ABCC1, ABCC8 and ABCD2 present potential modifiers of progression and response to the chemotherapy of breast carcinoma.

Differential toxicity biomarkers for irinotecan- and oxaliplatin-containing chemotherapy in colorectal cancer

PURPOSE

Oxaliplatin or irinotecan is usually administered jointly with fluoropyrimidines in colorectal cancer patients treated with chemotherapy. Both drugs have different toxicity patterns. Biomarkers for predicting high-risk severe adverse reactions can help select the best treatment.

METHODS

A retrospective analysis of 106 colorectal cancer patients receiving an oxaliplatin-based treatment and 56 receiving an irinotecan-based treatment was performed. One copy number variant (GSTT1) and nine polymorphisms in irinotecan and oxaliplatin metabolism, transport or DNA repair genes (ABCB1, UGT1A1, XRCC1, ERCC1, ERCC2, GSTP1) were genotyped by SNaPshot, polymerase chain reactions' length fragments, or copy number assays.

RESULTS

In irinotecan-treated patients, T allele of ABCB1C1236T SNP was associated with a lower risk of asthenia(OR = 0.047; 95 % CI = 0.004–0.493; P = 0.011) and Tallele of ABCB1 C3435T SNP was associated with a lower risk of diarrhea (OR = 0.177; 95 % CI = 0.034–0.919;P = 0.039), and individuals with two copies of GSTT1 gene had a lower risk for asthenia (OR = 0.093; 95 %CI = 0.011–0.794; P = 0.030). In oxaliplatin-treated patients, carriers of one or two T variants of Asn118Asn ERCC1 SNP had a lower risk for neutropenia(OR = 0.205; 95 % CI = 0.061–0.690; P = 0.01) [corrected].

CONCLUSIONS

These biomarkers could help oncologists select the best treatment by reducing toxicity associated with irinotecan or oxaliplatin in colorectal cancer patients, thus increasing their quality of life.

Fetal polymorphisms at the ABCB1-transporter gene locus are associated with susceptibility to non-syndromic oral cleft malformations

ATP-binding cassette (ABC) proteins in the placenta regulate fetal exposure to xenobiotics. We hypothesized that functional polymorphisms in ABC genes influence risk for non-syndromic oral clefts (NSOC). Both family-based and case-control studies were undertaken to evaluate the association of nine potentially functional single-nucleotide polymorphisms within four ABC genes with risk of NSOC. Peripheral blood DNA from a total of 150 NSOC case-parent trios from Singapore and Taiwan were genotyped, as was cord blood DNA from 189 normal Chinese neonates used as controls. In trios, significant association was observed between the ABCB1 single-nucleotide polymorphisms and NSOC (P<0.05). Only ABCB1 rs1128503 retained significant association after Bonferroni correction (odds ratio (OR)=2.04; 95% confidence interval (CI)=1.42-2.98), while rs2032582 and rs1045642 showed nominal significance. Association with rs1128503 was replicated in a case-control analysis comparing NSOC probands with controls (OR=1.58; 95% CI=1.12-2.23). A comparison between the mothers of probands and controls showed no evidence of association, suggesting NSOC risk is determined by fetal and not maternal ABCB1 genotype. The two studies produced a combined OR of 1.79 (95% CI=1.38-2.30). The T-allele at rs1128503 was associated with higher risk. This study thus provides evidence that potentially functional polymorphisms in fetal ABCB1 modulate risk for NSOC, presumably through suboptimal exclusion of xenobiotics at the fetal-maternal interface.

The role of ABC transporters in progression and clinical outcome of colorectal cancer

Worldwide, colorectal cancer (CRC) is the third most common cancer, with the highest mortality rates occurring in Central Europe. The use of chemotherapy to treat CRC is limited by the inter-individual variability in drug response and the development of cancer cell resistance. ATP-binding cassette (ABC) transporters play a crucial role in the development of resistance by the efflux of anticancer agents outside of cancer cells. The aim of this study was to explore transcript levels of all human ABCs in tumours and non-neoplastic control tissues from CRC patients collected before the first line of treatment by 5-fluorouracil (5-FU)-containing regimen. The prognostic potential of ABCs was evaluated by the correlation of transcript levels with clinical factors. Relations between transcript levels of ABCs in tumours and chemotherapy efficacy were also addressed. The transcript profile of all known human ABCs was assessed using real-time polymerase chain reaction with a relative standard curve. The majority of the studied ABCs were down-regulated or unchanged between tumours and control tissues. ABCA12, ABCA13, ABCB6, ABCC1, ABCC2 and ABCE1 were up-regulated in tumours versus control tissues. Transcript levels of ABCA12, ABCC7 and ABCC8 increased in direction from colon to rectum. Additionally, transcript levels of ABCB9, ABCB11, ABCG5 and ABCG8 followed the reverse significant trend, i.e. a decrease in direction from colon to rectum. The transcript level of ABCC10 in tumours correlated with the grade (P = 0.01). Transcript levels of ABCC6, ABCC11, ABCF1 and ABCF2 were significantly lower in non-responders to palliative chemotherapy in comparison with responders. The disease-free interval of patients treated by adjuvant chemotherapy was significantly shorter in patients with low transcript levels of ABCA7, ABCA13, ABCB4, ABCC11 and ABCD4. In conclusion, ABCC11 may be a promising candidate marker for a validation study on 5-FU therapy outcome.

Targeting MDR in breast and lung cancer: discriminating its potential importance from the failure of drug resistance reversal studies

This special issue of Drug Resistance Updates is dedicated to multidrug resistance protein 1 (MDR-1), 35 years after its discovery. While enormous progress has been made and our understanding of drug resistance has become more sophisticated and nuanced, after 35 years the role of MDR-1 in clinical oncology remains a work in progress. Despite clear in vitro evidence that P-glycoprotein (Pgp), encoded by MDR-1, is able to dramatically reduce drug concentrations in cultured cells, and that drug accumulation can be increased by small molecule inhibitors, clinical trials testing this paradigm have mostly failed. Some have argued that it is no longer worthy of study. However, repeated analyses have demonstrated MDR-1 expression in a tumor is a poor prognostic indicator leading some to conclude MDR-1 is a marker of a more aggressive phenotype, rather than a mechanism of drug resistance. In this review we will re-evaluate the MDR-1 story in light of our new understanding of molecular targeted therapy, using breast and lung cancer as examples. In the end we will reconcile the data available and the knowledge gained in support of a thesis that we understand far more than we realize, and that we can use this knowledge to improve future therapies.

Association of superoxide dismutases and NAD(P)H quinone oxidoreductases with prognosis of patients with breast carcinomas

Associations of transcript levels of oxidative stress-modifying genes SOD2, SOD3, NQO1 and NQO2 and their functional single nucleotide polymorphisms (SNPs) rs4880, rs1799895, rs2536512, rs699473, rs1800566 and rs1143684 with prognosis of breast cancer patients were studied. SNPs were assessed by allelic discrimination in a cohort of 321 breast cancer patients from the Czech Republic. Transcript levels were determined by real-time polymerase chain reaction (PCR) with absolute quantification in tumor and adjacent non-neoplastic control tissues. Both genotypes and transcript levels were then compared with available clinical data on patients. Patients carrying low activity allele Leu in NQO2 rs1143684 had a greater incidence of stage 0 or I disease (i.e., better prognosis) than patients with the Phe/Phe genotype. This association was more evident in patients without expression of progesterone receptors (p = 0.031). Patients carrying the Thr allele in SOD3 rs2536512 SNP had a significantly greater incidence of tumors expressing estrogen receptors than patients carrying the Ala/Ala genotype (p = 0.007). SOD3 transcript level was significantly higher in grade 1 or 2 tumors than in grade 3 tumors (p = 0.006). Patients carrying T allele in SOD3 rs699473 SNP had significantly poorer progression-free survival (PFS) than patients carrying the CC genotype (p = 0.038). The same applied to the subgroup of patients treated by hormonal regimens (p = 0.021). Patients carrying the high activity Ala/Ala genotype in SOD2 (rs4880) had significantly poorer PFS than Val allele carriers in the group treated by cyclophosphamide but not hormonal regimens (p = 0.004). Our results suggest that NQO2, SOD2 and SOD3 may significantly modify prognosis of breast cancer patients and that their significance should be further characterized.

Second-generation taxanes effectively suppress subcutaneous rat lymphoma: role of disposition, transport, metabolism, in vitro potency and expression of angiogenesis genes

The study investigated possible mechanisms by which second-generation taxanes, established as significantly more effective than paclitaxel in vitro, suppress a rat lymphoma model in vivo. The studied mechanisms included taxane pharmacokinetics, expression of genes dominating their metabolism (Cyp3a1/2) and transport (Abcb1) and genes controlling tumour angiogenesis (growth factors and receptors). SB-T-1214, SB-T-12854 and IDN5109 suppressed rat lymphoma more effectively than paclitaxel, SB-T-12851, SB-T-12852, SB-T-12853 or IDN5390 as well as P388D1 leukaemia cells in vitro. The greater anti-lymphoma effects of SB-T-1214 in rats corresponded to a higher bioavailability than with SB-T-12854, and lower systemic toxicity of SB-T-1214 for rats reflected its lower cytotoxicity for P388D1 cells in vitro. Suppression of Abcb1 and CYP3a1 expression by SB-T-1214 and IDN5109 could partly explain their anti-lymphoma effects, but not that of SB-T-12854. Growth factors genes Egf, Fgf, Pdgf, and Vegf associated with tumour angiogenesis had significantly lower expression following treatment with anti-lymphoma effective IDN5109 and their receptors were unaffected, whereas inefficient IDN5390 increased expression of the most important Vegf. The effective SB-T-12854 inhibited Egf, Egfr, Fgfr and Pdgfr expression, while the ineffective SB-T-12851, SB-T-12852 and SB-T-12853 inhibited only Egf or Egfr expression. Vegfr expression was inhibited significantly by SB-T-12851 and SB-T-12854, but effect of SB-T-12851 was compromised by induced Vegf expression. The very effective SB-T-1214 decreased the expression of Vegf, Egf and all receptors most prominently indicating the possible supporting role of these genes in anti-lymphoma effects. In conclusion, SB-T-1214, SB-T-12854 and IDN5109 are good candidates for further study.

Effect of ABCB1 C3435T polymorphism on docetaxel pharmacokinetics according to menopausal status in breast cancer patients

Background:

It can be hypothesised that inherited polymorphisms in the drug-transporter ABCB1 gene may interfere with interindividual variations in drug response in breast cancer patients. Docetaxel is a substrate for ABCB1 whose function has been shown to be modulated by oestrogen and progesterone.

Methods:

Whether ABCB1 polymorphisms including T-129C, A61G, C1236T, G2677T/A and C3435T polymorphisms could account for variations in the disposition of docetaxel and whether menopausal status at the time of diagnosis might interact with this effect were analysed in women receiving neoadjuvant chemotherapy for breast cancer (n=86).

Results:

A highly significant association was observed, but restricted to premenopausal women (n=53), between the pharmacokinetics of docetaxel and C3435T polymorphism, as patients with CC genotype had lower mean values of the area under the plasma concentration-time curve (AUC) of docetaxel than patients with CT and TT genotypes (P<0.0001). Comparison between pre- and postmenopausal women with the same C3435T genotype yielded a significant difference in docetaxel AUC only for CC genotype (P<0.0001).

Conclusion:

These results suggest that C3435T polymorphism genotyping and menopausal status at the time of diagnosis might be useful when considering chemotherapy regimens including docetaxel in breast cancer patients.