Nicotinamide riboside attenuates age-associated metabolic and functional changes in hematopoietic stem cells.

With age, hematopoietic stem cells (HSC) undergo changes in function, including reduced regenerative potential and loss of quiescence, which is accompanied by a significant expansion of the stem cell pool that can lead to haematological disorders. Elevated metabolic activity has been implicated in driving the HSC ageing phenotype. Here we show that nicotinamide riboside (NR), a form of vitamin B3, restores youthful metabolic capacity by modifying mitochondrial function in multiple ways including reduced expression of nuclear encoded metabolic pathway genes, damping of mitochondrial stress and a decrease in mitochondrial mass and network-size. Metabolic restoration is dependent on continuous NR supplementation and accompanied by a shift of the aged transcriptome towards the young HSC state, more youthful bone marrow cellular composition and an improved regenerative capacity in a transplant setting. Consequently, NR administration could support healthy ageing by re-establishing a more youthful hematopoietic system.

Germline Genetic Variants in GATA3 and Breast Cancer Treatment Outcomes in SWOG S8897 Trial and the Pathways Study.

INTRODUCTION: GATA3 is a critical transcription factor in maintaining the differentiated state of luminal mammary epithelial cells. We sought to determine the prognostic and predictive roles of GATA3 genotypes for breast cancer. PATIENTS AND METHODS: Twelve single nucleotide polymorphisms (SNPs) were genotyped in 2 breast cancer cohorts, including the SWOG S8897 trial where patients were treated with adjuvant chemotherapy (CAF [cyclophosphamide, doxorubicin, 5-fluorouracil] vs. CMF [cyclophosphamide, methotrexate, 5-fluorouracil]) or untreated, and the observational Pathways Study. RESULTS: In the S8897 trial, rs3802604 and rs568727 were associated with disease-free survival and overall survival in the treated group, regardless of chemotherapy regimen. The GG genotype of rs3802604 conferred poorer overall survival (adjusted hazard ratio, 2.45; 95% confidence interval, 1.48-4.05) and disease-free survival (adjusted hazard ratio, 1.95; 95% confidence interval, 1.27-2.99) compared with the AA genotype. Similar associations were found for rs568727. In contrast, no association with either SNP was found in the untreated group. Subgroup analyses indicated that these 2 SNPs more strongly influenced outcomes in the patients who also received tamoxifen. However, the associations in the subgroup with tamoxifen treatment were not replicated in the Pathways Study, possibly owing to substantial differences between the 2 patient cohorts, such as chemotherapy regimen and length of follow-up. Results from joint analyses across these 2 cohorts were marginally significant, driven by the results in S8897. Bioinformatic analyses support potential functional disruption of the GATA3 SNPs in breast tissue. CONCLUSIONS: The present study provides some evidence for the predictive value of GATA3 genotypes for breast cancer adjuvant therapies. Future replication studies in appropriate patient populations are warranted.

Selenium- or Vitamin E-Related Gene Variants, Interaction with Supplementation, and Risk of High-Grade Prostate Cancer in SELECT.

BACKGROUND: Epidemiologic studies and secondary analyses of randomized trials supported the hypothesis that selenium and vitamin E lower prostate cancer risk. However, the Selenium and Vitamin E Cancer Prevention Trial (SELECT) showed no benefit of either supplement. Genetic variants involved in selenium or vitamin E metabolism or transport may underlie the complex associations of selenium and vitamin E. METHODS: We undertook a case-cohort study of SELECT participants randomized to placebo, selenium, or vitamin E. The subcohort included 1,434 men; our primary outcome was high-grade prostate cancer (N = 278 cases, Gleason 7 or higher cancer). We used weighted Cox regression to examine the association between SNPs and high-grade prostate cancer risk. To assess effect modification, we created interaction terms between randomization arm and genotype and calculated log likelihood statistics. RESULTS: We noted statistically significant (P < 0.05) interactions between selenium assignment, SNPs in CAT, SOD2, PRDX6, SOD3, and TXNRD2, and high-grade prostate cancer risk. Statistically significant SNPs that modified the association of vitamin E assignment and high-grade prostate cancer included SEC14L2, SOD1, and TTPA In the placebo arm, several SNPs, hypothesized to interact with supplement assignment and risk of high-grade prostate cancer, were also directly associated with outcome. CONCLUSION: Variants in selenium and vitamin E metabolism/transport genes may influence risk of overall and high-grade prostate cancer, and may modify an individual man's response to vitamin E or selenium supplementation with regards to these risks. IMPACT: The effect of selenium or vitamin E supplementation on high-grade prostate cancer risk may vary by genotype. Cancer Epidemiol Biomarkers Prev; 25(7); 1050-8. ©2016 AACR.

Heterogeneous estrogen receptor expression in circulating tumor cells suggests diverse mechanisms of fulvestrant resistance.

Fulvestrant is a dose dependent selective estrogen receptor (ER) down-regulator (SERD) used in ER-positive metastatic breast cancer (MBC). Nearly all patients develop resistance. We performed molecular analysis of circulating tumor cells (CTC) to gain insight into fulvestrant resistance. Preclinical studies were performed with cultured breast cancer cells spiked into human blood and analyzed on the CellSearch(®) system. Clinical data are limited to a subset of patients with ER-positive MBC from a previously reported pilot trial whose disease was progressing on fulvestrant (N = 7) or aromatase inhibitors (AIs) (N = 10). CTCs were enumerated and phenotyped for ER and B-cell lymphoma (BCL2) using the CellSearch(®) CXC kit. In preclinical modeling, tamoxifen and AIs resulted in stabilized ER expression, whereas fulvestrant eliminated it. Five of seven patients progressing on fulvestrant had ≥5CTC/7.5 ml WB. Two of these five, treated with 500 mg/month fulvestrant, had no detectable CTC-expression of ER and BCL2 (an ER regulated gene). Three patients had heterogeneous CTC-ER and BCL2 expression indicating incomplete degradation of the ER target by fulvestrant. Two of these patients received 250 mg/month whereas the third patient received 500 mg/month fulvestrant. Her cancer harbored a mutation (Y537S) in the estrogen receptor alpha gene (ESR1). All seven ER positive patients progressing on AIs had heterogeneous CTC-ER expression. These results suggest heterogeneous mechanisms of resistance to fulvestrant, including insufficient dosage, ESR1 mutation, or conversion to dependence on non-ER pathways. CTC enumeration, phenotyping, and genotyping might identify patients who would benefit from fulvestrant dose escalation versus switching to alternative therapies.

Associations between genetic variants and the effect of letrozole and exemestane on bone mass and bone turnover.

Adjuvant therapy for hormone receptor (HR) positive postmenopausal breast cancer patients includes aromatase inhibitors (AI). While both the non-steroidal AI letrozole and the steroidal AI exemestane decrease serum estrogen concentrations, there is evidence that exemestane may be less detrimental to bone. We hypothesized that single nucleotide polymorphisms (SNP) predict effects of AIs on bone turnover. Early stage HR-positive breast cancer patients were enrolled in a randomized trial of exemestane versus letrozole. Effects of AI on bone mineral density (BMD) and bone turnover markers (BTM), and associations between SNPs in 24 candidate genes and changes in BMD or BTM were determined. Of the 503 enrolled patients, paired BMD data were available for 123 and 101 patients treated with letrozole and exemestane, respectively, and paired BTM data were available for 175 and 173 patients, respectively. The mean change in lumbar spine BMD was significantly greater for letrozole-treated (-3.2 %) compared to exemestane-treated patients (-1.0 %) (p = 0.0016). Urine N-telopeptide was significantly increased in patients treated with exemestane (p = 0.001) but not letrozole. Two SNPs (rs4870061 and rs9322335) in ESR1 and one SNP (rs10140457) in ESR2 were associated with decreased BMD in letrozole-treated patients. In the exemestane-treated patients, SNPs in ESR1 (Rs2813543) and CYP19A1 (Rs6493497) were associated with decreased bone density. Exemestane had a less negative impact on bone density compared to letrozole, and the effects of AI therapy on bone may be impacted by genetic variants in the ER pathway.

ESR1 and ESR2 polymorphisms in the BIG 1-98 trial comparing adjuvant letrozole versus tamoxifen or their sequence for early breast cancer.

Estrogen receptor 1 (ESR1) and ESR2 gene polymorphisms have been associated with endocrine-mediated physiological mechanisms, and inconsistently with breast cancer risk and outcomes, bone mineral density changes, and hot flushes/night sweats. DNA was isolated and genotyped for six ESR1 and two ESR2 single-nucleotide polymorphisms (SNPs) from tumor specimens from 3691 postmenopausal women with hormone receptor-positive breast cancer enrolled in the BIG 1-98 trial to receive tamoxifen and/or letrozole for 5 years. Associations with recurrence and adverse events (AEs) were assessed using Cox proportional hazards models. 3401 samples were successfully genotyped for five SNPs. ESR1 rs9340799(XbaI) (T>C) variants CC or TC were associated with reduced breast cancer risk (HR = 0.82,95% CI = 0.67-1.0), and ESR1 rs2077647 (T>C) variants CC or TC was associated with reduced distant recurrence risk (HR = 0.69, 95% CI = 0.53-0.90), both regardless of the treatments. No differential treatment effects (letrozole vs. tamoxifen) were observed for the association of outcome with any of the SNPs. Letrozole-treated patients with rs2077647 (T>C) variants CC and TC had a reduced risk of bone AE (HR = 0.75, 95% CI = 0.58-0.98, P interaction = 0.08), whereas patients with rs4986938 (G>A) genotype variants AA and AG had an increased risk of bone AE (HR = 1.37, 95% CI = 1.01-1.84, P interaction = 0.07). We observed that (1) rare ESR1 homozygous polymorphisms were associated with lower recurrence, and (2) ESR1 and ESR2 SNPs were associated with bone AEs in letrozole-treated patients. Genes that are involved in estrogen signaling and synthesis have the potential to affect both breast cancer recurrence and side effects, suggesting that individual treatment strategies can incorporate not only oncogenic drivers but also SNPs related to estrogen activity.

Manganese superoxide dismutase polymorphism, treatment-related toxicity and disease-free survival in SWOG 8897 clinical trial for breast cancer.

To date, the few studies of associations between a functional polymorphism in the oxidative stress-related gene manganese superoxide dismutase (SOD2) and breast cancer survival have been inconsistent. In a homogeneous patient population from a large cooperative group trial Southwest Oncology Group (SWOG) 8897, we evaluated this polymorphism in relation to both treatment-related toxicity and disease-free survival (DFS). Among 458 women who received cyclophosphamide-containing adjuvant chemotherapy, those with variant C alleles, related to higher antioxidant activity, experienced less grade 3-4 neutropenia (OR = 0.52, 95% CI = 0.29-0.92) but had worse DFS (HR = 1.59, 95% CI = 0.99-2.55) than women with TT genotypes. No associations were observed among 874 women who were followed without adjuvant therapy. Our results are consistent with the hypothesis that women with higher SOD2 antioxidant activity may experience less treatment-related toxicity but shorter time to disease recurrence or death after breast cancer adjuvant chemotherapy, supporting the modifying effects of oxidative stress-related enzymes on cancer treatment toxicity and efficacy.

Myeloperoxidase genotypes and enhanced efficacy of chemotherapy for early-stage breast cancer in SWOG-8897.

PURPOSE: Myeloperoxidase (MPO) generates reactive oxygen species and also activates xenobiotics. In a rigorous clinical trial (Southwest Oncology Group SWOG-8897), we examined relationships between genotypes and disease-free survival (DFS) among women treated for breast cancer, as well as those who did not receive adjuvant chemotherapy. PATIENTS AND METHODS: Patients were assigned to risk groups according to standard prognostic features; the low-risk group (n = 753 genotyped) received follow-up only, and the high-risk group (n = 401 genotyped) was randomly assigned to adjuvant cyclophosphamide, methotrexate, and fluorouracil (CMF) or cyclophosphamide, doxorubicin, and fluorouracil (CAF), with or without tamoxifen. DNA from archived normal lymph node tissue was genotyped, and Cox proportional hazard models were used to calculate DFS associated with MPO genotypes. RESULTS: Among women in the treatment arm, those with MPO G alleles had more than a two-fold reduction in hazard of recurrence (adjusted hazard ratio [HR] for GA genotypes, 0.51; 95% CI, 0.21 to 0.99; HR for GG genotypes, 0.41; 95% CI, 0.21 to 0.77). Effects were greatest among women who were further randomly assigned to tamoxifen (HR for GA genotypes, 0.28; 95% CI, 0.12 to 0.69; HR for GG genotypes, 0.19; 95% CI, 0.08 to 0.45). There were no significant associations between genotypes and DFS among women in the untreated arm, and relationships between genotypes and DFS did not differ by CAF or CMF. CONCLUSION: These results, observed in two independent study populations, indicate that high-activity MPO genotypes are associated with better survival among women receiving cyclophosphamide-containing therapy, particularly when followed by tamoxifen therapy. MPO can be inhibited and/or upregulated by commonly used drugs; thus, our findings merit further investigation for optimization of therapeutics for breast cancer.

Nitric oxide synthase variants and disease-free survival among treated and untreated breast cancer patients in a Southwest Oncology Group clinical trial.

PURPOSE: Numerous chemotherapeutic agents are cytotoxic through generation of reactive species, and variability in genes related to oxidative stress may influence disease-free survival (DFS). We examined relationships between DFS and variants in NOS3, as well as NQO1, NQO2, and CBR3, among treated and untreated breast cancer patients in a Southwest Oncology Group clinical trial (S8897). EXPERIMENTAL DESIGN: In the parent trial, women were assigned according to prognostic features; the high-risk group was randomized to cyclophosphamide, i.v. methotrexate, and 5-fluorouracil or to cyclophosphamide, i.v. doxorubicin, and 5-fluorouracil +/- tamoxifen, and the low-risk group did not receive adjuvant therapy. We extracted DNA from normal lymph node tissue and examined functional polymorphisms in NOS3, NQO1, NQO2, and CBR3, in relation to DFS, using Cox proportional hazard model. RESULTS: There were significant interactions between DFS, adjuvant therapy, and NOS3 Glu298Asp and -786 polymorphisms, alone and in combination (P for interaction = 0.008). When NOS3 genotypes were combined, women with genotypes encoding for lower nitric oxide who received chemotherapy had a >2-fold increase in hazard of progression (hazard ratio, 2.32; 95% confidence interval, 1.26-4.25), whereas there was reduced risk for those who did not receive adjuvant therapy (hazard ratio, 0.42; 95% confidence interval, 0.19-0.95). There were no associations between the other genotypes and DFS in either group. CONCLUSION: Variants encoding lower activity of NOS3 may affect outcomes in breast cancer patients, with the direction of risk differing depending on chemotherapy status. These results may mirror the known dual functions of nitric oxide and nitric oxide synthase, depending on oxidative environment.

Evaluation of novel epidermal growth factor receptor tyrosine kinase inhibitors.

The epidermal growth factor system is a well characterized growth factor receptor pathway, the deregulation of which has been be associated with neoplastic growth. Overexpression or amplification of the epidermal growth factor receptor (EGFR) or one of its ligands has been linked with the malignant transformation of cells and is correlated with poor prognosis in patients. PD 153035, a quinazoline, has been shown to inhibit the tyrosine kinase activity of EGFR by blocking ATP binding (Fry et al., Science 265: 1093-1095, 1994). We set out to determine whether the growth inhibition caused by this agent and five related compounds is a direct result of the blocking of EGFR signaling. The effects on cell proliferation produced by these agents were tested on several tumor cell lines and EC50 values obtained. The EGF responsive cell lines A-431 and MDA-MB-468 exhibit EC50 values of 3 and 6.7 micro M, respectively, for PD 153035 which was found to be the most potent. The agents were then tested for their ability to block the paradoxical high dose EGF induced inhibition of A-431 and MDA-MB-468 cell growth as well as EGF induced phosphorylation in A-431 cells. These compounds are able to completely block the effects of exogenously added EGF at 0.5 microM or less. However, higher doses (EC50's >or= 2 microM) were needed to block the growth of human tumor cell lines potentially implicating a second site of action for these compounds.

Common origins of MDA-MB-435 cells from various sources with those shown to have melanoma properties.

Recently, the tissue origin of MDA-MB-435 cell line has been the subject of considerable debate. In this study, we set out to determine whether MDA-MB-435-DTP cells shown to express melanoma-specific genes were identical to various other MDA-MB-435 cell stocks worldwide. CGH-microarray, genetic polymorphism genotyping, microsatellite fingerprint analysis and/or chromosomal number confirmed that the MDA-MB-435 cells maintained at the Lombardi Comprehensive Cancer Center (MDA-MB-435-LCC) are almost identical to the MDA-MB-435-DTP cells, and showed a very similar profile to those obtained from the same original source (MD Anderson Cancer Center) but maintained independently (MDA-MB-435-PMCC). Gene expression profile analysis confirmed common expression of genes among different MDA-MB-435-LCC cell stocks, and identified some unique gene products in MDA-MB-435-PMCC cells. RT-PCR analysis confirmed the expression of the melanoma marker tyrosinase across multiple MDA-MB-435 cell stocks. Collectively, our results show that the MDA-MB-435 cells used widely have identical origins to those that exhibit a melanoma-like gene expression signature, but exhibit a small degree of genotypic and phenotypic drift.

Sodium current in human jejunal circular smooth muscle cells.

BACKGROUND & AIMS: Sodium channels are key regulators of neuronal and muscle excitability. However, sodium channels have not been definitively identified in gastrointestinal smooth muscle. The aim of the present study was to determine if a Na(+) current is present in human jejunal circular smooth muscle cells. METHODS: Currents were recorded from freshly dissociated cells using patch-clamp techniques. Complementary DNA (cDNA) libraries constructed from the dissociated cells were screened to determine if a message for alpha subunits of Na(+) channels was expressed. Smooth muscle cells were also collected using laser-capture microdissection and screened. RESULTS: A tetrodotoxin-insensitive Na(+) channel was present in 80% of cells patch-clamped. Initial activation was at -65 mV with peak inward current at -30 mV. Steady-state inactivation and activation curves revealed a window current between -75 and -60 mV. The Na(+) current was blocked by lidocaine and internal and external QX314. A cDNA highly homologous to SCN5A, the alpha subunit of the cardiac Na(+) channel, was present in the cDNA libraries constructed from dissociated cells and from smooth muscle cells collected using laser-capture microdissection. CONCLUSIONS: Human jejunal circular smooth muscle cells express a tetrodotoxin-insensitive Na(+) channel, probably SCN5A. Whether SCN5A plays a role in the pathophysiology of human gut dysmotilities remains to be determined.