African ancestry and higher prevalence of triple-negative breast cancer

BACKGROUND: The study of breast cancer in women with African ancestry offers the promise of identifying markers for risk assessment and treatment of triple-negative disease. METHODS: African American and white American women with invasive cancer diagnosed at the Henry Ford Health System comprised the primary study population, and Ghanaian patients diagnosed and/or treated at the Komfo Anokye Teaching Hospital in Kumasi, Ghana constituted the comparison group. Formalin-fixed, paraffin-embedded specimens were transported to the University of Michigan for histopathology confirmation, and assessment of estrogen and progesterone receptors and HER-2/ neu expression. RESULTS: The study population included 1008 white Americans, 581 African Americans, and 75 Ghanaians. Mean age at diagnosis was 48.0 years for Ghanaian, 60.8 years for African American, and 62.4 for white American cases ( P = .002). Proportions of Ghanaian, African American, and white American cases with estrogen receptor-negative tumors were 76%, 36%, and 22%, respectively ( P < .001), and proportions with triple-negative disease were 82%, 26%, and 16%, respectively ( P < .001). All Ghanaian cases were palpable, locally advanced cancers; 57 (76%) were grade 3. A total of 147 American women were diagnosed as stage III or IV; of these, 67.5% (n = 46) of African Americans and 44.6% (n = 29) of white Americans were grade 3. Among palpable, grade 3 cancers, Ghanaians had the highest prevalence of triple-negative tumors (82.2%), followed by African Americans (32.8%) and white Americans (10.2%). CONCLUSIONS: Our study demonstrates progressively increasing frequency of estrogen receptor-negative and triple-negative tumors among breast cancer patients with white American, African American, and Ghanaian/African backgrounds. This pattern indicates a need for additional investigations correlating the extent of African ancestry and high-risk breast cancer subtypes. Cancer 2010. © 2010 American Cancer Society.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78243/1/25276_ftp.pd

Copy number and gene expression differences between African American and Caucasian American prostate cancer

<p>Abstract</p> <p>Background</p> <p>The goal of our study was to investigate the molecular underpinnings associated with the relatively aggressive clinical behavior of prostate cancer (PCa) in African American (AA) compared to Caucasian American (CA) patients using a genome-wide approach.</p> <p>Methods</p> <p>AA and CA patients treated with radical prostatectomy (RP) were frequency matched for age at RP, Gleason grade, and tumor stage. Array-CGH (BAC SpectralChip2600) was used to identify genomic regions with significantly different DNA copy number between the groups. Gene expression profiling of the same set of tumors was also evaluated using Affymetrix HG-U133 Plus 2.0 arrays. Concordance between copy number alteration and gene expression was examined. A second aCGH analysis was performed in a larger validation cohort using an oligo-based platform (Agilent 244K).</p> <p>Results</p> <p>BAC-based array identified 27 chromosomal regions with significantly different copy number changes between the AA and CA tumors in the first cohort (Fisher's exact test, P < 0.05). Copy number alterations in these 27 regions were also significantly associated with gene expression changes. aCGH performed in a larger, independent cohort of AA and CA tumors validated 4 of the 27 (15%) most significantly altered regions from the initial analysis (3q26, 5p15-p14, 14q32, and 16p11). Functional annotation of overlapping genes within the 4 validated regions of AA/CA DNA copy number changes revealed significant enrichment of genes related to immune response.</p> <p>Conclusions</p> <p>Our data reveal molecular alterations at the level of gene expression and DNA copy number that are specific to African American and Caucasian prostate cancer and may be related to underlying differences in immune response.</p

No major association between TGFBR1*6A and prostate cancer

Background: Transforming Growth Factor Beta (TGF-ß) is one of the most potent inhibitor of cell growth 1. Almost all cancer cells loose the ability to be growth inhibited by TGF-ß, which makes loss of TGF-ß growth inhibition a hallmark of cancer development 2. TGFBR1*6A is a common variant of the type I TGF-ß receptor, TGFBR1 3. TGFBR1*6A (*6A) has a deletion of three GCG triplets coding for alanine within a nine alanine (9A) repeat sequence of TGFBR1 (*9A) exon 1, resulting in a six alanine (6A) repeat sequence. The 9-bp deletion that differentiates *6A from *9A is located within the predicted signal sequence cleavage region. In vitro studies have demonstrated that TGFBR1*6A responds less effectively than TGFBR1 to TGF-ß growth inhibitory signals 45. The additional findings of an overrepresentation of TGFBR1*6A heterozygotes and homozygotes among patients with a diagnosis of cancer as compared with the general population led us to postulate that TGFBR1*6A might act as a tumor susceptibility allele 5. Two recent meta-analyses show that TGFBR1*6A carriers may have an increased risk of breast, colon and ovarian cancer 67. To test the hypothesis that TGFBR1*6A may contribute to the development of prostate cancer, we conducted a case control study of patients with biopsy verified prostate cancer cases and geographically and ethnic-status matched controls. Results: A total of 907 cases and controls were genotyped for TGFBR1*6A. The mean age of cases was significantly higher than controls (p 55, 55 0.01 9A/9A 334 (87.2) 80 (81.6) 1.00 1.00 9A/6A or 6A/6A 49 (12.8) 18 (18.4) 0.64 (0.36–1.17) 0.57 (0.30–1.10) 1 OR was adjusted for race. 2 OR was adjusted for race and age strata within age groups Discussion: Prostate cancer is the most common cancer and the second most common cause of cancer death among U.S. men 8. A similar pattern is observed throughout the western world. There is strong epidemiologic evidence indicating that a large proportion of prostate cancers are caused by heritable factors. The most convincing data is a study of 44,788 Scandinavian twins showing that 42% of prostate cancer cancers may be caused by shared genes 9. Despite intense efforts led by several research teams, the search for prostate cancer susceptibility genes has thus far remained elusive. Recent studies suggest that carriers of deleterious mutations of the BRCA2 gene have an increased prostate cancer risk 10. However, given the low prevalence of deleterious BRCA2 mutations in the general population, it is unlikely to account for a significant proportion of prostate cancer cases. Approximately 14% of the general population carries at least one copy of TGFBR1*6A, which makes it the most common candidate tumor susceptibility allele reported to date. While there is growing evidence that TGFBR1*6A predisposes to the development of breast, colon and ovarian cancer, our data do not suggest that it predisposes to the development of prostate cancer. We have previously shown that TGFBR1*6A homozygotes have an O.R of 2.69 and 2.02 for ovarian and colon cancer, respectively. The present study has the power to detect an O.R. for prostate cancer of 1.70 or higher and therefore rules out a major association between TGFBR1*6A and prostate cancer. However, it does not exclude a smaller O.R., which might have clinical relevance given the high TGFBR1*6A allelic frequency in the general population. It is possible that age differences in cases and controls affected the allele frequencies observed. If the TGFBR1*6A allele predisposes to a lethal malignancy such as prostate cancer, however, its frequency could be higher, not lower, in a younger cohort. Thus, the younger mean age of controls could result in a bias toward the null hypothesis, resulting in a stronger association than that observed. The intriguing findings of a high TGFBR1*6A allelic frequency among prostate cancer cases diagnosed before the age of 55 have to be cautiously interpreted given the fact that this group only included 46 patients. We have previously shown that TGFBR1*6A is not associated with an increased risk of bladder cancer 6. Our results suggest that the association between TGFBR1*6A and prostate cancer is at best very weak but further studies are needed to formally exclude an association with early onset prostate cancer. Methods: DNA was extracted from lymphocytes of blood specimens from 465 consecutive individuals diagnosed with adenocarcinoma of the prostate who received care at the outpatient urology clinic at Memorial Sloan-Kettering Cancer Center from April 2000 to September 2002. The blood samples were collected following completion of diagnostic studies. They were unselected for age or family history. Clinical and pathological records were reviewed to confirm the diagnosis of prostate cancer in all subjects. Once pathological diagnosis of prostate cancer was confirmed, the age of diagnosis was recorded, and all other identifying links were destroyed. The study design and anonymization method were approved by the Memorial Sloan-Kettering Cancer Center Institutional Review Board. A population of 465 healthy male controls aged 20 to 87 years with well-defined ethnic background who had donated blood for various reasons (predominantly pre-natal screening for non-cancer disease) constituted the control group. Controls were matched to the cases on ethnicity and were from the same geographic locations as the prostate cancer cases. None of the controls had any personal history of cancer at the time of blood donation. This was ascertained by a questionnaire completed by each control. Exact age information was not available for 205 controls since it was not collected prospectively but the age range (20 to 40) was known. All personal identifiers were permanently removed from both cases and controls. DNA was extracted by standard technique using the Qiagen DNA extraction kit. The PCR primers used were 5'-CCA CAG GCG GTG GCG GCG CGA TG-3' in the forward direction and 5'-CGT CGC CCC CGG GAF CAG CGC CGC-3' in the reverse direction. A standard solution was prepared using the Clontech Advantage® GC rich kit (BD-Biosciences Clontech, Palo Alto, CA). The PCR reaction mixture included 20 ng of genomic DNA in a 10-µL reaction volume and the following concentration of other reagents: primers (0.25 µM each), 1X GC genomic PCR reaction buffer, 1.625 mM Mg2+, 0.2 mM dNTPs and 0.16 µL of Advantage-GC genomic polymerase mix. Polymerase chain reaction cycling conditions consisted of an initial denaturation period of 3 minutes at 94°C, then 35 cycles of denaturation for 30 seconds at 94°C and annealing/extension for 2 minutes at 72°C, followed by a final extension step of 5 minutes at 72°C. Quality controls were run on a 2% agarose gel. The ABI Prism 310 Genetic Analyzer (Applied Biosystems, Foster City, CA) was used for data acquisition. A peak at 115 base pairs corresponded to TGFBR1 allele, whereas a peak at 107 base pairs corresponded to the TGFBR1*6A variant. The rare equivocal results were confirmed by cloning of the PCR product followed by automated sequencing. Samples were read by two independent investigators unaware of the case /control status. Ten percent of samples were randomly selected and run for quality assurance. Concordance rate was 100%. Statistical analysis Distributions of TGFBR1 genotypes, age, and ethnicity were compared between cases and controls using Fisher's exact tests. To test the hypothesis that the hypomorphic TGFBR1*6A gene is related to an increased prostate cancer risk, adjusted odds ratios of prostate cancer were estimated using both conditional and unconditional logistic regression models. Both models were run since the matched controls of cases with missing genotypes had to be excluded in the conditional models but could be included in the unconditional models. Adjusted odds ratios of prostate cancer were estimated comparing carriers of TGFBR1*6A versus non-carriers under dominant models. Potential confounders such as age (in four strata) and ethnicity were controlled in the analysis. Whether the effects of TGFBR1*6A on prostate cancer differ by age was evaluated by stratified analysis and tests for multiplicative interaction. A small p value indicates that interaction of age and gene is statistically significant on the multiplicative level. For the unconditional models, sensitivity analysis was conducted to evaluate the impact of the fact that the exact age of some controls with age 20–40 years is unknown (N = 126). With 442 cases and 465 controls, the power to detect an OR of 1.7 and 2 in the present study was 0.86 and 0.98, respectively, based on a two-tailed test at the 0.05 significance level. Authors' contributions: All authors made substantial contributions to this paper, including conceiving of the ideas, discussion and writing. All authors read and approved the final manuscript

Spatial control of Cdc42 signalling by a GM130-RasGRF complex regulates polarity and tumorigenesis

The small GTPase Cdc42 is a key regulator of polarity, but little is known in mammals about its spatial regulation and the relevance of spatial Cdc42 pools for polarity. Here we report the identification of a GM130-RasGRF complex as a regulator of Cdc42 at the Golgi. Silencing GM130 results in RasGRF-dependent inhibition of the Golgi pool of Cdc42, but does not affect Cdc42 at the cell surface. Furthermore, active Cdc42 at the Golgi is important to sustain asymmetric front-rear Cdc42-GTP distribution in directionally migrating cells. Concurrent to Cdc42 inhibition, silencing GM130 also results in RasGRF-dependent Ras-ERK pathway activation. Moreover, depletion of GM130 is sufficient to induce E-cadherin downregulation, indicative of a loss in cell polarity and epithelial identity. Accordingly, GM130 expression is frequently lost in colorectal and breast cancer patients. These findings establish a previously unrecognized role for a GM130-RasGRF-Cdc42 connection in regulating polarity and tumorigenesis

Polymorphisms in the glucocerebrosidase gene and pseudogene urge caution in clinical analysis of Gaucher disease allele c.1448T>C (L444P)

BACKGROUND: Gaucher disease is a potentially severe lysosomal storage disorder caused by mutations in the human glucocerebrosidase gene (GBA). We have developed a multiplexed genetic assay for eight diseases prevalent in the Ashkenazi population: Tay-Sachs, Gaucher type I, Niemann-Pick types A and B, mucolipidosis type IV, familial dysautonomia, Canavan, Bloom syndrome, and Fanconi anemia type C. This assay includes an allelic determination for GBA allele c.1448T>C (L444P). The goal of this study was to clinically evaluate this assay. METHODS: Biotinylated, multiplex PCR products were directly hybridized to capture probes immobilized on fluorescently addressed microspheres. After incubation with streptavidin-conjugated fluorophore, the reactions were analyzed by Luminex IS100. Clinical evaluations were conducted using de-identified patient DNA samples. RESULTS: We evaluated a multiplexed suspension array assay that includes wild-type and mutant genetic determinations for Gaucher disease allele c.1448T>C. Two percent of samples reported to be wild-type by conventional methods were observed to be c.1448T>C heterozygous using our assay. Sequence analysis suggested that this phenomenon was due to co-amplification of the functional gene and a paralogous pseudogene (ΨGBA) due to a polymorphism in the primer-binding site of the latter. Primers for the amplification of this allele were then repositioned to span an upstream deletion in the pseudogene, yielding a much longer amplicon. Although it is widely reported that long amplicons negatively impact amplification or detection efficiency in recently adopted multiplex techniques, this assay design functioned properly and resolved the occurrence of false heterozygosity. CONCLUSION: Although previously available sequence information suggested GBA gene/pseudogene discrimination capabilities with a short amplified product, we identified common single-nucleotide polymorphisms in the pseudogene that required amplification of a larger region for effective discrimination

Estimating the survival benefits gained from providing national cancer genetic services to women with a family history of breast cancer

The aim of this paper is to compare a service offering genetic testing and presymptomatic surveillance to women at increased risk of developing breast cancer with its predecessor of no service at all in terms of survival and quality-adjusted survival (QALYs) by means of a Markov cohort chain simulation model. Genetic assessment and presymptomatic care provided between 0.07-1.61 mean additional life years and 0.05-1.67 mean QALYs over no services. Prophylactic surgery and surveillance extended mean life expectancy by 0.41-1.61 and 0.32-0.99 years, respectively over no services for high-risk women. Model outcomes were sensitive to all the parameters varied in the sensitivity analysis. Providing cancer genetic services increase survival and as long as services do not induce adverse psychological effects they also provide more QALYs. The greatest survival and QALY benefits were found for women with identified mutations. As more cancer genes are identified, the survival and cost-effectiveness of genetic services will improve. Although mastectomy provided most additional life years, when quality of life was accounted for oophorectomy was the optimal strategy. Delayed entry into coordinated genetic services was found to diminish the average survival and QALY gains for a woman utilising these services

A combined analysis of outcome following breast cancer: differences in survival based on BRCA1/BRCA2 mutation status and administration of adjuvant treatment

BACKGROUND: The prognostic significance of germline mutations in BRCA1 and BRCA2 in women with breast cancer remains unclear. A combined analysis was performed to address this uncertainty. METHODS: Two retrospective cohorts of Ashkenazi Jewish women undergoing breast-conserving treatment for invasive cancer between 1980 and 1995 (n = 584) were established. Archived tissue blocks were used as the source of DNA for Ashkenazi Jewish BRCA1/BRCA2 founder mutation analysis. Paraffin-embedded tissue and follow-up information was available for 505 women. RESULTS: Genotyping was successful in 496 women, of whom 56 (11.3%) were found to carry a BRCA1/BRCA2 founder mutation. After a median follow-up period of 116 months, breast cancer specific survival was worse in women with BRCA1 mutations than in those without (62% at 10 years versus 86%; P < 0.0001), but not in women with the BRCA2 mutation (84% versus 86% at 10 years; P = 0.76). Germline BRCA1 mutations were an independent predictor of breast cancer mortality in multivariate analysis (hazard ratio 2.4, 95% confidence interval 1.2–4.8; P = 0.01). BRCA1 status predicted breast cancer mortality only among women who did not receive chemotherapy (hazard ratio 4.8, 95% confidence interval 2.0–11.7; P = 0.001). The risk for metachronous ipsilateral cancer was not greater in women with germline BRCA1/BRCA2 founder mutations than in those without mutations (P = 0.68). CONCLUSION: BRCA1 mutations, but not BRCA2 mutations, are associated with reduced survival in Ashkenazi women undergoing breast-conserving treatment for invasive breast cancer, but the poor prognosis associated with germline BRCA1 mutations is mitigated by adjuvant chemotherapy. The risk for metachronous ipsilateral disease does not appear to be increased for either BRCA1 or BRCA2 mutation carriers, at least up to 10 years of follow up