Concordance testing between Powerplex ESI 16 Fast System and VeriFiler Express.

DNA profiles generated by different STR kits may show different alleles for identical amplified loci. This well-known phenomenon affects the smooth transition of data generated by new STR kits to a database or casework laboratory or cross-laboratory comparison of STR profiles. As in other DNA databases throughout the world, it has become clear that the number of the analyzed loci should be expanded for a variety of reasons, such as partial profiles resulting from low copy-number DNA template or degraded samples, working with mixtures or when prevalence of familial inbreeding. In the course of introducing a new STR kit, VeriFiler™ Express (Applied Biosystems, Foster City, CA, USA), we compared genotyping data of 1568 samples amplified by the VeriFiler™ Express with the data generated on the same samples by the Powerplex™ ESI FAST (Promega, Madison WI, USA) kit. Discordance was noted in 20 samples (1.27%), 14 (0.89%) of them showing allele dropout mismatch and six (0.38%) showing an additional fixed-size third allele. These rates are well above the reported rates of 0.4% for this kit. Since correct genotyping and accurate consistent allele assignment is of paramount importance, it seems timely to recommend for DNA laboratories and genetic-match search systems to take these possible inconsistencies into account.

The rate of the recurrent MSH6 mutations in Ashkenazi Jewish breast cancer patients.

BACKGROUND: Whether breast cancer (BC) should be considered within the spectrum of tumors in Lynch syndrome (LS) is unsettled. Recently, MSH6 and PMS2 germline mutations have reportedly been associated with an increased BC risk and with hereditary breast and ovarian cancer (HBOC) phenotype. We assessed the rates of the recurring Ashkenazi Jewish (AJ) mutations in the MSH6 gene (c.3984_3987dupGTCA and c.3959_3962delCAAG) in AJ cases with seemingly sporadic BC or HBOC phenotype, who were negative for the founder AJ BRCA1/2 mutations. METHODS: All AJ individuals, affected with BC ≤ 70 years and/or ovarian cancer at any age who were counseled, genotyped and tested negative for the BRCA1/2 founder mutations between January 2010 and February 2018 at the Oncogenetics unit, Sheba Medical Center, were genotyped for the AJ mutations in MSH6. RESULTS: Of 1016 genotyped participants (815 BC cases, 132 ovarian cancer cases, and 69 with more than one cancer), five carriers (0.49%) of the recurring AJ mutations in MSH6 were identified. All had BC, and two had personal history of additional cancers (pancreatic, endometrial, colorectal). The rate of MSH6 mutations was 0.93% (4/429) when considering only cases with a personal or first-degree relative with LS-related cancer, and 0.17% (1/587) of cases with second-degree relative or no family history of LS-related cancers (p = 0.087). CONCLUSIONS: Our data suggest the spectrum of genotyped mutations in AJ BC patients with a personal or family history of LS-related cancers should be expanded. These data should be validated in other populations with a similar phenotype.

Accuracy of Risk Prediction Models for Breast Cancer and BRCA1/BRCA2 Mutation Carrier Probabilities in Israel.

BACKGROUND/AIM: Several algorithms have been developed to assess the risk of predicting BRCA mutation and breast cancer (BC) risk. The aim of this study was to evaluate the accuracy of these prediction algorithms in the Israeli population. PATIENTS AND METHODS: Risk for developing breast cancer and the probability for carrying BRCA1/2 mutations using BOADICEA, BRCAPRO, IBIS, MYRIAD and PENN2 models were computed for individuals counseled and genotyped at the Oncogenetics unit in 2000 and 2005. The predicted mutation carriers and BC risks were compared with actual carrier rates by genotyping and BC diagnoses derived from the Israeli National Cancer Registry database. RESULTS: Overall, 65/648 (10%) study participants were BRCA1/2 mutation carriers. Of 373 cancer-free participants at counseling, 25 had breast cancer by 2016. BOADICEA and BRCAPRO performed best for predicting BRCA mutation (AUC=0.741, 0.738, respectively). No model was clinically useful in predicting breast cancer risk. CONCLUSION: BOADICEA and BRCAPRO outperformed the other tested algorithms in BRCA mutation prediction in Israeli women, but none was valuable in breast cancer risk prediction.

Mutational analysis of candidate genes in Israeli male breast cancer cases.

PURPOSE: To define the mutational spectrum of several candidate gene mutations in Israeli male breast cancer cases. METHODS: MBC cases counselled at the Oncogenetics unit, Sheba Medical Center from January 1998 to June 2017 were included. Relevant clinical and oncological data and cancer phenotype were retrieved. All participants were genotyped for the predominant Jewish BRCA1 and BRCA2 germline mutations using a chip-based assay. Those who tested negative were further genotyped for three recurring mutations in CHEK2 (c.1100delC, p.S428F, p.I157T), and single mutations in the FANCM (c.5791C>T), and RAD51D (c.556C>T) genes, by direct sequencing. The ethics committee approved the study. RESULTS: Overall, 61 MBC were identified and genotyped, 41 (67.2%) were Ashkenazim, age at diagnosis was 58.1 ± 12.6 years, and 31 (50.8%) had a family history of cancer. Of genotyped individuals, one (1.6%) harboured the 185delAG* BRCA1 mutation, 7 (11.4%) the 6174delT*BRCA2 mutation and 2 (3.2%) other recurring mutations in BRCA2 (overall 10/61-16.4% BRCA1/BRCA2 mutation carriers). Of BRCA-negative cases, 3/51 (5.9%) carried the p.S428F *CHEK2 mutation. None was a carrier of the other genotyped mutations in CHEK2, FANCM or RAD51D. CONCLUSION: BRCA1, BRCA2 and CHEK2 germline mutations contribute to inherited predisposition to MBC in Israel.

Are VNTRs co-localizing with breast cancer-associated SNPs?

PURPOSE: Several common genetic variants (single-nucleotide polymorphisms, SNPs) have been shown to be associated with breast cancer (BC) risk in the general population, and to modify BC risk for BRCA1 and BRCA2 mutation carriers. Co-localization of variable number of tandem repeats (VNTRs) with these BC-associated SNPS has not been comprehensively studied. METHODS: Cross referencing of genome-wide VNTRs with the known BC genome-wide association studies (GWAS) SNPs significantly associated with increased risk for developing breast cancer was carried out. Analysis was based on the overlap between the VNTRs and 10-kb windows around these BC-susceptibility SNPs. RESULTS: Cross referencing of the 1.2 million TR with the 161 known BC-associated SNPs in the general population led to 690 matches. Of those, in 17 VNTRs, the SNP was within the VNTR. Analysis restricted to loci known to modify BC penetrance in BRCA1 (n = 31) and BRCA2 (n = 33) mutation carriers led to 139 and 170 co-localization matches, respectively. For these, none of the SNPs were within the VNTR. The distances between the SNPs and the VNTRs were not significantly different from what was expected to occur by chance alone (p = 0.61; p = 0.44; p = 0.25, respectively). CONCLUSION: There is no evidence that VNTRs co-localize with currently reported SNP tagged BC GWAS loci.

The yield of targeted genotyping for the recurring mutations in BRCA1/2 in Israel.

BACKGROUND: Hereditary breast cancer is predominantly associated with germline mutations in the BRCA1 or BRCA2 genes. A few recurring mutations in these genes were reported in ethnically diverse Jewish populations. Since 2013, most oncogenetic laboratories in Israel adopted a two-step approach for BRCA1/2 genotyping, where the first step is genotyping for 14 seemingly recurring mutations-first-pass genotyping. The aim of this study was to assess the yield of this targeted BRCA sequencing. METHODS: Clinical and genotyping data of all individuals who underwent oncogenetic counseling and first-pass BRCA genotyping at the Oncogenetic Service Sheba and Assaf Harofeh Medical Centers from 1 February 2013 to 30 June 2017 were reviewed. All study participants were unrelated to each other. RESULTS: Overall, 5152 oncogenetic tests were reviewed in the present study, of which 4452 had no a priori known familial mutation. The majority of participants (68.6%) were genotyped because of personal history of cancer; 20.6% were tested because of family history of cancer, and details for the remaining 10.7% were missing. Overall, 256/4452 (5.8%) carriers were detected, 141 BRCA1 and 115 BRCA2 mutation carriers. In 54% of cancer-free carriers, no clinically suspicious family history of cancer was ascertained. CONCLUSIONS: The currently used scheme of first-pass genotyping in Israel seems to have a high yield of mutation detection even in the absence of a significant family history of cancer. The challenge is to optimize the currently used targeted panel of common mutations and adjust it to the accumulating new data in the Israeli population.

Spectrum of germline mutations in smokers and non-smokers in Brazilian non-small-cell lung cancer (NSCLC) patients.

Lung cancer (LC) is a leading cause of cancer-related mortality. Although smoking is the major risk factor, ~15% of all cases occur in never-smokers, suggesting that genetic factors play a role in LC predisposition. Indeed, germline mutations in the TP53 gene predispose to multiple cancer types, including LC. To date, few studies compared the somatic and germline mutational profiles of LC cases by smoking status, and none was reported in Brazilians. Whole-exome sequencing (WES) was performed on two pools (seven smokers and six non-smokers) of tumor-derived DNA using the Illumina HiSeq2000 platform. Files from pools were analyzed separately using Ingenuity®Variant AnalysisTM and Mendel,MD. Validation of all candidate variants was performed by Sanger sequencing. Subsequently, validated mutations were analyzed in germline DNA from the same patients and in ethnically matched controls. In addition, a single recurring Brazilian TP53 germline mutation (R337H) was genotyped in 45 non-small-cell lung cancer patients.Four novel germline variants in the ATAD2, AURKA, PTPRD and THBS1 genes were identified exclusively in smoker patients, and four germline missense variants in PLCD1, RAD52, CP and CDC6 genes were identified solely in non-smokers. There were 4/45 (8.9%) germline carriers of the R337H TP53 mutation. In conclusion, the recurring Brazilian TP53 mutation should be genotyped in all non-small-cell lung cancer in Brazil, regardless of smoking status. Distinct pathogenic mutations and novel sequence variants are detected in Brazilian non-small-cell lung cancer patients, by smoking status. The contribution of these sequence variants to LC pathogenesis remains to be further explored.

Inherited predisposition to breast and ovarian cancer in non-Jewish populations in Israel.

PURPOSE: The contribution of genetic factors to cancer in non-Jewish populations in Israel is understudied. Yet the early, mostly premenopausal age at breast cancer diagnosis is suggestive of an inherited predisposition. METHODS: High-risk cancer cases of non-Jewish origin who were counseled at the Oncogenetics unit, Sheba Medical Center and the oncology institute at the Ziv medical center from January 1, 2000 to December 31 2016 were eligible. DNA extracted from leukocytes was subjected to massive parallel, next-generation sequencing using the Color Genomics platform. Data were analyzed for pathogenic and likely pathogenic mutations using existing pipelines. RESULTS: Overall, 68 cases, each representing a unique high-risk breast/ovarian family, were genotyped: 32 Druze, 26 Muslim Arabs, and 10 Christian Arabs. Fifty-nine had breast cancer (mean age at diagnosis 42.7 ± 7.6 years), and 9 had ovarian cancer (51.6 ± 9.7 years). Overall three pathogenic mutations one each in BRCA1, PALB2, and BRIP1 genes were detected mostly in Druze families. In addition, 29 variants of unknown significance were also detected, and in 36 cases no sequence variants were noted in any of the genotyped genes. CONCLUSION: The contribution of the known cancer susceptibility genes to the burden of inherited breast/ovarian cancer predisposition in non-Jews in Israel is modest. Other genes or molecular mechanisms account for the familial breast/ovarian cancer clustering in this population.

Colorectal and Endometrial Cancer Risk and Age at Diagnosis in BLMAsh Mutation Carriers.

BACKGROUND: Biallelic BLM gene mutation carriers are at an increased risk for cancer, including colorectal cancer (CRC). Whether heterozygous BLM gene mutations confer an increased cancer risk remains controversial. OBJECTIVES: To evaluate CRC and endometrial cancer risk in BLM heterozygous mutation carriers. METHODS: Jewish Ashkenazim at high risk for colon or endometrial cancer and endometrial cancer cases unselected for family history were genotyped for the BLMAsh predominant mutation. RESULTS: Overall, 243 high-risk individuals were included: 97 men CRC patients (55.12 ± 12.3 years at diagnosis), 109 women with CRC (56.5 ± 13.7 years), 32 women with endometrial cancer (58.25 ± 13.4 years) and 5 women with both CRC and endometrial cancer. In addition, 120 unselected Ashkenazi women with endometrial cancer (64.2 ± 11.58 years) were genotyped. The BLMAsh mutation was present in 4/243 (1.65%) high-risk patients; 2 CRC (0.97%) 2 endometrial cancer (5.4%), and 1/120 unselected endometrial cancer patients (0.84%). Notably, in high-risk cases, BLMAsh mutation carriers were diagnosed at a younger age (for CRC 47.5 ± 7.8 years; P = 0.32 ; endometrial cancer 49.5 ± 7.7 years; P = 0.36) compared with non-carriers. CONCLUSIONS: Ashkenazi high risk CRC/endometrial cancer, and women with endometrial cancer have a higher rate of BLMAsh heterozygous mutation compared with the general population. BLMAsh heterozygous mutation carriers are diagnosed with CRC and endometrial cancer at a younger age compared with non-carriers. These observations should be validated and the possible clinical implications assessed.

The rate of recurrent BRCA1, BRCA2, and TP53 mutations in the general population, and unselected ovarian cancer cases, in Belo Horizonte, Brazil.

In Brazil, several recurring mutations in BRCA1 and BRCA2 and a TP53 mutation (R337H) have been reported in high risk breast cancer cases. We hypothesized that these recurring mutations may also be detected in the general population and ovarian cancer cases in the state of Minas Gerais. To test this notion, participants were recruited from the outpatient and the Gynecological clinic in the UFMG Medical Center in Belo Horizonte, Minas Gerais, Brazil. BRCA1 (c.68_69delAG, c.5266dupC, c.181T>G, c.4034delA, c.5123C>A), BRCA2 (c.5946delT, c.8537_8538delAG, 4936_4939delGAAA), the c.156_157insAlu* BRCA2 and the c.1010G>A *TP53 mutation were genotyped using validated techniques. Overall, 513 cancer free participants (273 men) (mean age 47.7 ± 15.1 years) and 103 ovarian cancer cases (mean age at diagnosis 58.7 ± 9.6 years) were studied. None of the participants were found to carry any of the genotyped mutations. We conclude that the recurring mutations in BRCA1, BRCA2 and TP53 cannot be detected in the general population or consecutive ovarian cancer cases in this geographical region in Brazil.

MiR-377 targets E2F3 and alters the NF-kB signaling pathway through MAP3K7 in malignant melanoma.

BACKGROUND: The incidence of cutaneous malignant melanoma continues to rise, and once the disease metastasizes it is almost inevitably fatal. We recently reported that a large miRNAs cluster on human chromosome 14q32, implicated in many types of cancers, is significantly down-regulated in melanoma. miR-377, one of the miRNAs located within this cluster, was studied here. METHODS: qRT-pCR was used to quantify miR-377 levels in melanoma cell lines and samples. Melanoma cell lines ectopically expressing miR-377 were generated by stable transfection, mRNA expression was assessed using mRNA arrays and protein expression was assessed by Western blot analysis. Potential targets of miR-377 were identified through luciferase reporter assays. Cellular proliferation, migration and soft-agar colony formation were monitored in control and miR-377-expressing cells using cell biology techniques. RESULTS: miR-377 is expressed in normal melanocytes but not in melanoma cell lines or samples. Its ectopic stable expression in melanoma cell lines decreased their proliferative and migratory capacity and their colony-forming capability. mRNA arrays of melanoma cells over-expressing miR-377 pointed to several down-regulated mRNAs that have putative binding sites for miR-377 in their 3'UTR, of which both E2F3 and MAP3K7 were found to be direct targets of miR-377. E2F3, a potent transcriptional inducer of cell-cycle progression, was found to be elevated in melanoma cell lines, but decreased following ectopic expression of miR-377. Ectopic miR-377 also led to a decrease in the activity of a reporter plasmid containing three E2F DNA-binding sites linked to a luciferase cDNA sequence, demonstrating that miR-377 down-regulates E2F3-induced transcription. MAP3K7 (known as TAK1), a serine/threonine kinase along the MAPK signaling pathway, was over-expressed in melanoma but decreased following ectopic expression of miR-377. MAP3K7 is involved in the activation of NF-κB. MiR-377 over-expression led to decreased activity of a reporter plasmid containing two NF-κB DNA-binding sites and to decreased output along the NF-kB signaling pathway. CONCLUSION: Our results suggest that miR-377 is an important negative regulator of E2F and MAP3K7/NF-kB signaling pathway in melanoma cells; it is tempting to speculate that its silencing in melanoma promotes the tumorigenic and metastatic potential of the cells through activation of these pathways.

Cancer risks in Jewish male BRCA1 and BRCA2 mutation carriers.

Cancer risks and tumor types in male BRCA1 and BRCA2 mutation carriers are still unsettled. Cancer risks in men who were found to harbor a BRCA1 (n = 150) or a BRCA2 (n = 88) mutation or both (n = 2) were assessed by cross referencing with data on cancer occurrence in the Israeli National Cancer Registry. Incidence rates in mutation carriers were compared with men who were counseled, genotyped, and found not to harbor the familial mutation (true negative n = 122), and with standardized incidence rates (SIRs). Of 210 cancer-free individuals at initial counseling, 11 cancers were diagnosed after a mean follow-up of 5.06 ± 4.1 years (1064 person/years) compared with 1/122 in a BRCA true-negative man. The SIR for all BRCA1/2 mutation carriers compared with the rates in the general population were elevated for pancreatic cancer [2.97 (95 % CI 1.83-4.29)] and breast cancer [16.44 (95 % CI 9.65-26.24)]. For prostate cancer these rates were 0.59 (95 % CI 0.4-0.84). Jewish BRCA1/2 mutation carriers are at an increased risk for breast and pancreatic, but not prostate cancer. These cancer risks and the consequent recommendations, if validated, should be transmitted to carriers at test result disclosure.

BRCA1 is expressed in uterine serous carcinoma (USC) and controls insulin-like growth factor I receptor (IGF-IR) gene expression in USC cell lines.

OBJECTIVE: The insulin-like growth factor I receptor (IGF-IR) and BRCA1 affect cell growth and apoptosis. Little information is available about BRCA1 activity on the IGF signaling pathway. This study evaluated the effect of BRCA1 on IGF-IR expression. METHODS: BRCA1 and IGF-IR immunohistochemistry on archival tissues (35 uterine serous carcinomas [USCs] and 17 metastases) were performed. USPC1 and USPC2 cell lines were transiently cotransfected with an IGF-IR promoter construct driving a luciferase reporter gene and a BRCA1 expression plasmid. Endogenous IGF-IR levels were evaluated by Western immunoblotting. RESULTS: We found high BRCA1 and IGF-IR protein expression in primary and metastatic USC tumors. All samples were immunostained for BRCA1-71% strongly stained; and 33/35 (94%) were stained positive for IGF-IR-2 (6%) strongly stained. No difference in BRCA1 and IGF-IR staining intensity was noted between BRCA1/2 mutation carriers and noncarriers. Metastatic tumors stained more intensely for BRCA1 than did the primary tumor site (P = 0.041) and with borderline significance for IGF-IR (P = 0.069). BRCA1 and IGF-IR staining did not correlate to survival. BRCA1 expression led to 35% and 54% reduction in IGF-IR promoter activity in the USPC1 and USCP2 cell lines, respectively. Western immunoblotting showed a decline in phosphorylated IGF-IR and phosphorylated AKT in both transiently and stably transfected cells. CONCLUSIONS: BRCA1 and IGF-IR are highly expressed in USC tumors. BRCA1 suppresses IGF-IR gene expression and activity. These findings suggest a possible biological link between the BRCA1 and the IGF-I signaling pathways in USC. The clinical implications of this association need to be explored.

Differential regulation of insulin-like growth factor-I receptor gene expression by wild type and mutant androgen receptor in prostate cancer cells.

The progression of prostate cancer from an organ-confined, androgen-sensitive disease to a metastatic one is associated with dysregulation of androgen receptor (AR)-regulated target genes and with a decrease in insulin-like growth factor-I receptor (IGF-IR) expression. To investigate the differential effects of wild type (wt) and mutant AR on IGF-IR levels we employed a series of isogenic prostate-derived cell lines and human xenografts. We show that basal and phosphorylated IGF-IR levels progressively decreased as prostate cancer cells became more tumorigenic and metastatic. In addition, we show that wt, but not mutant, AR along with dihydrotestosterone treatment increased IGF-IR promoter activity and endogenous IGF-IR levels. ChIP analysis show enhanced AR binding to the IGF-IR promoter in AR-overexpressing cells. Finally, wt AR-overexpressing cells display an enhanced proliferation rate. In summary, we provide evidence that activated wt AR enhances IGF-IR transcription in prostate cancer cells via a mechanism that involves AR binding to the IGF-IR promoter. AR mutations alter the ability of the mutated protein to regulate IGF-IR expression. Our results suggest that prostate cancer progression is associated with a decrease in IGF-IR expression that could be the result of impaired ability of AR to stimulate IGF-IR gene expression.

Progression to metastatic stage in a cellular model of prostate cancer is associated with methylation of the androgen receptor gene and transcriptional suppression of the insulin-like growth factor-I receptor gene.

The progression of prostate cancer from an organ-confined, androgen-sensitive disease to a metastatic one is associated with dysregulation of androgen receptor (AR)-regulated target genes and with a decrease in insulin-like growth factor-I receptor (IGF1R) expression. DNA methylation of CpG islands is an epigenetic mechanism associated with gene silencing. Recent studies have demonstrated that methylation occurs early in prostate carcinogenesis and, furthermore, may contribute to androgen independence. The methylation status of the AR and IGF1R genes was evaluated in a series of prostate cancer cell lines corresponding to early (benign) and advanced (metastatic) stages of the disease. Results of 5-Aza-2'-deoxycytidine (5-Aza) experiments, methylation-specific PCR, and sodium bisulfite-direct DNA sequencing revealed that the AR promoter is hypermethylated in metastatic M12, but not in benign P69, cells. On the other hand, no methylation was seen in the IGF1R promoter at any stage of the disease. We show, however, that 5-Aza treatment, which caused demethylation of the AR promoter, led to a significant increase in IGF1R mRNA levels, whereas addition of the AR inhibitor flutamide decreased the IGF1R mRNA levels to basal values measured prior to the 5-Aza treatment. Given that the IGF1R gene has been identified as a downstream target for AR action, our data is consistent with a model in which the AR gene undergoes methylation during progression of the disease, leading to dysregulation of AR targets, including the IGF1R gene, at advanced metastatic stages.

Transcription factor E2F1 is a potent transactivator of the insulin-like growth factor-I receptor (IGF-IR) gene.

OBJECTIVES: The insulin-like growth factor-I receptor (IGF-IR) plays an important role in cancer development. The E2F1 transcription factor activates S-phase promoting genes and mediates apoptosis. Microarray analyses of E2F1-induced genes revealed that genes associated with proliferation as well as apoptosis are upregulated by E2F1. Among other candidate genes, DNA microarrays identified the IGF-IR gene as a putative E2F1 target. The aim of this study was to investigate the involvement of E2F1 in regulation of IGF-IR gene transcription. METHODS: To examine the potential regulation of IGF-IR gene expression by E2F1, an E2F1 expression vector was transfected into P69 and M12 prostate cancer cell lines, after which IGF-IR levels were measured by Western blots. Transient transfections were used to evaluate IGF-IR promoter activity and chromatin immunoprecipitation (ChIP) assays were employed to assess E2F1-binding to the IGF-IR promoter. RESULTS: Results obtained showed that E2F1 expression induced a significant increment in endogenous IGF-IR levels. ChIP assays showed enhanced E2F1-binding to the IGF-IR promoter in E2F1-expressing cells. Transient coexpression of an E2F1 vector along with an IGF-IR promoter-luciferase reporter resulted in a approximately 140-fold increase in IGF-IR promoter activity. Furthermore, deletion and bioinformatic analyses indicate that the ability of E2F1 to stimulate IGF-IR promoter activity was correlated with the number of E2F1 sites in the promoter region. CONCLUSIONS: In summary, we provide evidence that E2F1 regulates IGF-IR gene transcription in prostate cancer cells via a mechanism that involves direct binding to specific elements in the proximal IGF-IR promoter.

Tumor suppressor BRCA1 is expressed in prostate cancer and controls insulin-like growth factor I receptor (IGF-IR) gene transcription in an androgen receptor-dependent manner.

PURPOSE: The insulin-like growth factor (IGF) system plays an important role in prostate cancer. The BRCA1 gene encodes a transcription factor with tumor suppressor activity. The involvement of BRCA1 in prostate cancer, however, has not yet been elucidated. The purpose of the present study was to examine the functional correlations between BRCA1 and the IGF system in prostate cancer. EXPERIMENTAL DESIGN: An immunohistochemical analysis of BRCA1 was done on tissue microarrays comprising 203 primary prostate cancer specimens. In addition, BRCA1 levels were measured in prostate cancer xenografts and in cell lines representing early stages (P69 cells) and advanced stages (M12 cells) of the disease. The ability of BRCA1 to regulate IGF-I receptor (IGF-IR) expression was studied by coexpression experiments using a BRCA1 expression vector along with an IGF-IR promoter-luciferase reporter. RESULTS: We found significantly elevated BRCA1 levels in prostate cancer in comparison with histologically normal prostate tissue (P<0.001). In addition, an inverse correlation between BRCA1 and IGF-IR levels was observed in the androgen receptor (AR)-negative prostate cancer-derived P69 and M12 cell lines. Coexpression experiments in M12 cells revealed that BRCA1 was able to suppress IGF-IR promoter activity and endogenous IGF-IR levels. On the other hand, BRCA1 enhanced IGF-IR levels in LNCaP C4-2 cells expressing an endogenous AR. CONCLUSIONS: We provide evidence that BRCA1 differentially regulates IGF-IR expression in AR-positive and AR-negative prostate cancer cells. The mechanism of action of BRCA1 involves modulation of IGF-IR gene transcription. In addition, immunohistochemical data are consistent with a potential survival role of BRCA1 in prostate cancer.

Insulin-like growth factor-i regulates Kruppel-like factor-6 gene expression in a p53-dependent manner.

High-circulating IGF-I concentrations are associated with an increased risk for breast, prostate, and colorectal cancer. Krüppel-like factor-6 (KLF6) is a zinc finger tumor suppressor inactivated in prostate and other types of cancer. We have previously demonstrated that KLF6 is a potent transactivator of the IGF-I receptor promoter. The aim of the present study was to examine the potential regulation of KLF6 gene expression by IGF-I. The human colon cancer cell lines HCT116 +/+ and -/- (with normal and disrupted p53, respectively) were treated with IGF-I. Western blots, quantitative RT-PCR, and transfection assays were used to evaluate the effect of IGF-I on KLF-6 production. Signaling pathway inhibitors were used to identify the mechanisms responsible for regulation of KLF6 expression. Small interfering RNA against p53 and KLF6 was used to assess the role of p53 in regulation of KLF6 expression by IGF-I and to evaluate KLF6 involvement in cell cycle control. Results obtained showed that IGF-I stimulated KLF-6 transcription in cells with normal, but not disrupted, p53, suggesting that KLF6 is a downstream target for IGF-I action. Stimulation of KLF6 expression by IGF-I in a p53-dependent manner may constitute a novel mechanism of action of IGF-I, with implications in normal cell cycle progression and cancer biology.