IGFBP3 polymorphisms and risk of cancer: a meta-analysis

IGF-binding proteins

Insulin-like growth factor-binding proteins (IGFBPs) 1-6 bind IGFs but not insulin with high affinity. They were initially identified as serum carriers and passive inhibitors of IGF actions. However, subsequent studies showed that, although IGFBPs inhibit IGF actions in many circumstances, they may also potentiate these actions. IGFBPs are widely expressed in most tissues, and they are flexible endocrine and autocrine/paracrine regulators of IGF activity, which is essential for this important physiological system. More recently, individual IGFBPs have been shown to have IGF-independent actions. Mechanisms underlying these actions include (i) interaction with non-IGF proteins in compartments including the extracellular space and matrix, the cell surface and intracellular space, (ii) interaction with and modulation of other growth factor pathways including EGF, TGF-β and VEGF, and (iii) direct or indirect transcriptional effects following nuclear entry of IGFBPs. Through these IGF-dependent and IGF-independent actions, IGFBPs modulate essential cellular processes including proliferation, survival, migration, senescence, autophagy and angiogenesis. They have been implicated in a range of disorders including malignant, metabolic, neurological and immune diseases. A more complete understanding of their cellular roles may lead to the development of novel IGFBP-based therapeutic opportunities.

Insulin-like growth factor (IGF) axis in cancerogenesis

Determination of the role of insulin-like growth factor (IGF) family components in carcinogenesis of several human tumors is based on numerous epidemiological and pre-clinical studies, experiments in vivo and in vitro and on attempts at application of drugs affecting the IGF axis. Investigative hypotheses in original studies were based on biological functions manifested by the entire family of IGF (ligands, receptors, linking proteins, adaptor molecules). In the context of carcinogenesis the most important functions of IGF family involve intensification of proliferation and inhibition of cell apoptosis and effect on cell transformation through synthesis of several regulatory proteins. IGF axis controls survival and influences on metastases of cells. Interactions of IGF axis components may be of a direct or indirect nature. The direct effects are linked to activation of PI3K/Akt signaling pathway, in which the initiating role is first of all played by IGF-1 and IGF-1R. Activity of this signaling pathway leads to an increased mitogenesis, cell cycle progression, and protection against different apoptotic stresses. Indirect effects of the axis depend on interactions between IGF and other molecules important for cancer etiology (e.g. sex hormones, products of suppressor genes, viruses, and other GFs) and the style of life (nutrition, physical activity). From the clinical point of view, components of IGF system are first of all considered as diagnostic serous and/or tissue biomarkers of a given cancer, prognostic factors and attractive target of modern anti-tumor therapies. Several mechanisms in which IGF system components act in the process of carcinogenesis need to be clarified, mainly due to multifactorial etiology of the neoplasms. Pin-pointing of the role played in carcinogenesis by any single signaling pathway remains particularly difficult. The aim of this review is to summarize the current data of several epidemiological studies, experiments in vitro and on animal models, to increase our understanding of the complex role of IGF family components in the most common human cancers.

MicroRNA-197 Mediates the Overgrowth and Anti-Apoptotic Effects by Downregulating Insulin-Like Growth Factor-Binding Protein-3 During Nephroblastoma Tumorigenesis

MiR-197 is frequently upregulated to induce a series of oncogenic effects, which is closely associated with poor survival and prognosis of multiple malignancies. However, the roles of miR-197 in tumorigenesis and the detailed molecular mechanism in Wilms tumor (WT) have rarely been reported. This study aimed to evaluate the expression of miR-197 in WT in vivo and the potential effects of miR-197 on the proliferation and apoptosis in SK-NEP-1 cells. A total of 15 patients with a pathologically confirmed diagnosis of WT and 15 paraneoplastic controls were enrolled. Real-time quantitative PCR (RT-qPCR) identified the upregulation of miR-197 and downregulation of insulin-like growth factors binding protein 3 (IGFBP3) in WT tissues in comparison with adjacent normal tissue (p < 0.001). CCK-8 and flow cytometry assay found that inhibition of miR-197 caused a significantly reduced proliferation along with a dramatically enhanced apoptosis of SK-NEP-1 cells (p < 0.01). IGFBP3 was overexpressed in SK-NEP-1 cells by pEGFP-C1-IGFBP3 plasmid transfection. Overexpression of IGFBP3 suppressed the proliferation and induced the apoptosis of SK-NEP-1 cells (p < 0.01). Further study detected the decreased IGFBP3 expression with miR-197 mimics SK-NEP-1 cells and increased IGFBP3 expression with miR-197 inhibitor SK-NEP-1 cells compared with mock (p < 0.01). Dual luciferase reporter assay revealed a direct interaction between miR-197 and 3'-UTR site of IGFBP3. Overall, the above results indicated that miR-197 targeted IGFBP3 to induce the overgrowth and anti-apoptotic effects of WT cells, which could promote nephroblastoma tumorigenesis. Therefore, miR-197 may be further assessed as a potential target for the treatment of WT.

Polymorphisms of insulin-like growth factor binding protein-3 as a predictor for risk and patient survival in esophageal squamous cell carcinoma

BACKGROUND AND PURPOSE

Genetic single nucleotide polymorphisms (SNP) play a critical role in the development of esophageal squamous cell carcinoma (ESCC). The aim of this study is to investigate the associations between insulin-like growth factor binding protein-3 (IGFBP-3) gene polymorphisms and ESCC patients risk and survival after definitive chemoradiotherapy (CRT).

MATERIALS AND METHODS

We undertook a case-control study to analyze two IGFBP-3 polymorphisms (rs2854744 A>C and rs2854746 G>C) in an Han Chinese population, by extraction of genomic DNA from the peripheral blood of 110 ESCC patients treated with CRT and 128 control participants, and performed IGFBP-3 genotyping using DNA sequencing.

RESULTS

The obtained results indicated that overall, no statistically significant association was observed in rs2854746 G>C. However, rs2854744 A>C genotype was at increased risk of ESCCs (P=0.032; odds ratio (OR)=1.201, CI 95%:1.014-1.423). Moreover, rs2854744 A>C genotype ESCCs were more significantly common in patients with tumor size of >6cm than A allele ESCC and in cases of lower T stage. Furthermore, ESCC patients with rs2854744CC genotype have the poorer CRT response and shorter survival time than GG+GC genotype ESCC.

CONCLUSIONS

In conclusion, polymorphism in IGFBP-3 rs2854744 A>C might be a potential predictor of ESCC risk and patient survival. Nevertheless, further investigation with a larger sample size is needed to support our results.

Urinary aHGF, IGFBP3 and OPN as diagnostic and prognostic biomarkers for prostate cancer

AIM

Serum PSA screening for prostate cancer (PCa) is controversial. Here, we identify three urinary biomarkers - aHGF, IGFBP3 and OPN - for PCa screening and prognostication.

METHODS

Urinary aHGF, OPN and IGFBP3 from healthy men (n = 19) and men with localized (n = 65) and metastatic (n = 36) PCa were quantified via ELISA. Mann-Whitney nonparametric t-test and the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) analyses were used to analyze associations.

RESULTS

Mean aHGF and IGFBP3 levels were significantly elevated in PCa patients versus controls (p = 0.0006 and p = 0.0012, respectively), and the area under the curve of the receiver operating characteristic curve (indicator of diagnostic accuracy) for aHGF and IGFBP3 was 0.75 and 0.74, respectively. OPN levels were significantly higher in metastatic groups (p = 0.0060) versus localized and controls (area under the curve = 0.68).

CONCLUSION

Urinary aHGF and IGFBP3 exhibit the capacity for diagnostic discrimination for PCa, whereas OPN may indicate presence of metastatic disease.

Meta-analysis of the association between insulin-like growth factor binding protein 3 genetic polymorphisms and colorectal cancer susceptibility

Insulin-like growth factor binding protein 3 (IGFBP-3) plays an important role in the development and progress of cancers. The association between IGFBP-3 polymorphisms and colorectal cancer remains controversial and ambiguous. The aim of this study is to explore the association between IGFBP3 A-202C and Gly32Ala polymorphisms and colorectal cancer susceptibility using meta-analysis. Case-control studies on the association between IGFBP3 A-202C and Gly32Ala polymorphisms and colorectal cancer, which had sufficient data for estimating an odds ratio (OR) with 95% confidence interval (CI), were included in the meta-analysis. Abstracts, case reports, editorials, and review articles were excluded. Heterozygous and homozygous mutants were compared with the wild types to estimate combined OR values and 95%CIs with Review Manager 5.0. Six eligible studies were included, with 3157 patients and 6027 controls for A-202C and 1711 patients and 2995 controls for Gly32Ala. No significant association was found in all genetic models (for A-202C, AC vs. AA, OR = 0.99(0.88-1.11), CC vs. AA, OR = 1.06(0.92-1.22), dominant model, OR = 0.98(0.88-1.09), recessive model, OR = 0.94(0.84-1.05); and for Gly32Ala polymorphism, GC vs. GG, OR = 1.10(0.92-1.31), CC vs. GG, OR = 0.93(0.76-1.14), dominant model, OR = 1.05(0.89-1.24), recessive model, OR = 0.90(0.77-1.05)). The results suggest that the IGFBP3 A-202C and Gly32Ala polymorphisms are not associated with colorectal cancer susceptibility.

The impact of IGF-I gene polymorphisms on coronary artery disease susceptibility

BACKGROUND

Coronary artery disease (CAD) was the second leading cause of death for the past 3 years in Taiwan. The insulin-like growth factor (IGF) system is considered a new risk factor of CAD because investigations show that the levels and bioactivity of IGF-I and IGFBP-3 (where IGFBP is insulin-like growth factor-binding protein) may be involved in elevating the risk of CAD. This study investigated the relationships among IGF-I +1770, IGF-I +6093, and IGFBP-3 -202 genetic polymorphisms and CAD in the Taiwanese population.

METHODS

A total of 581 subjects, including 390 non-CAD controls and 191 patients with CAD, were recruited and the isolated DNA was subjected to real-time polymerase chain to evaluate the effects of these three polymorphic variants on CAD.

RESULTS

Our results showed a significant association between the IGF-I +1770 gene polymorphism and increased risk of CAD. Furthermore, CAD patients with a minimum of one mutant C allele, T/C or C/C, in IGF-I +1770 gene polymorphism had significantly high blood pressure including systolic blood pressure (SBP; P = 0.025) and diastolic blood pressure (DBP; P = 0.004), compared to CAD patients with T/T homozygotes. Moreover, CAD patients with a minimum of one mutant A allele, G/A or A/A, in the IGF-I +6093 gene polymorphism had a 1.695-fold elevated risk of congestive heart failure (CHF), compared to CAD patients with the G/G homozygote.

CONCLUSIONS

Polymorphism of IGF-I +1770 was associated with increased CAD risk. In CAD patients, the contributions of IGF-I +1770 and +6093 could be through the effect on blood pressure in CAD patients.

Ovarian cysts during tamoxifen use may affect the prognostic markers of premenopausal breast cancer

OBJECTIVES

Only a few studies have suggested the association between ovarian cysts and serum estrogen levels during tamoxifen use. However, increased estrogen levels with ovarian cysts would affect the prognosis of breast cancer; this association has not yet been studied. We aimed to investigate the association between ovarian cysts and prognostic markers in premenopausal breast cancer patients undergoing tamoxifen treatment.

METHODS

A retrospective review of 65 premenopausal breast cancer patients who underwent tamoxifen treatment was performed. Serum hormone levels were measured either specifically between cycle days 2 and 5 in menstruating patients or at any time in amenorrheic participants.

RESULTS

The study population consisted of premenopausal patients with (n = 23) and without ovarian cysts (n = 42). Serum estradiol (E(2)) levels and tumor markers were not statistically different based on ovarian cyst status. In the subgroup analysis, serum E(2) levels were significantly higher in menstruating women with ovarian cysts, and E(2) levels were positively correlated with serum cancer antigen 15-3 and insulin-like growth factor-1 in these women.

CONCLUSIONS

Ovarian cysts during tamoxifen use may affect the markers associated with the clinical course of premenopausal breast cancer.

Genetic variation in insulin pathway genes and distal colorectal adenoma risk

BACKGROUND

Insulin, glucose, and other insulin-related proteins that mediate insulin signaling are associated with colorectal neoplasia risk, but associations with common genetic variation in insulin axis genes are less clear. In this study, we used a comprehensive tag single-nucleotide polymorphisms (SNPs) approach to define genetic variation in six insulin axis genes (IGF1, IGF2, IGFBP1, IGFBP3, IRS1, and IRS2) and three genes associated with estrogen signaling (ESR1, ESR2, and PGR).

METHODS

We assessed associations between SNPs and distal colorectal adenoma (CRA) risk in a case-control study of 1,351 subjects. Cases were individuals with one or more adenomas diagnosed during sigmoidoscopy, and controls were individuals with no adenomas at the sigmoidoscopy exam. We used unconditional logistic regression assuming an additive model to assess SNP-specific risks adjusting for multiple comparisons with P (act).

RESULTS

Distal adenoma risk was significantly increased for one SNP in IGF2 [per minor allele OR = 1.41; 95 % confidence interval (CI) = 1.16, 1.67; P (act) = 0.005] and decreased for an ESR2 SNP (per minor allele OR = 0.78; 95 % CI = 0.66, 0.91; P (act) = 0.041). There was no statistically significant heterogeneity of these associations by race, sex, BMI, physical activity, or, in women, hormone replacement therapy use. Risk estimates did not differ in the colon versus rectum or for smaller (<1 cm) versus larger (>1 cm) adenomas.

CONCLUSIONS

These data suggest that selected genetic variability in IGF2 and ESR2 may be modifiers of CRA risk.

Performance of an adipokine pathway-based multilocus genetic risk score for prostate cancer risk prediction

Few biomarkers are available to predict prostate cancer risk. Single nucleotide polymorphisms (SNPs) tend to have weak individual effects but, in combination, they have stronger predictive value. Adipokine pathways have been implicated in the pathogenesis. We used a candidate pathway approach to investigate 29 functional SNPs in key genes from relevant adipokine pathways in a sample of 1006 men eligible for prostate biopsy. We used stepwise multivariate logistic regression and bootstrapping to develop a multilocus genetic risk score by weighting each risk SNP empirically based on its association with disease. Seven common functional polymorphisms were associated with overall and high-grade prostate cancer (Gleason≥7), whereas three variants were associated with high metastatic-risk prostate cancer (PSA≥20 ng/mL and/or Gleason≥8). The addition of genetic variants to age and PSA improved the predictive accuracy for overall and high-grade prostate cancer, using either the area under the receiver-operating characteristics curves (P<0.02), the net reclassification improvement (P<0.001) and integrated discrimination improvement (P<0.001) measures. These results suggest that functional polymorphisms in adipokine pathways may act individually and cumulatively to affect risk and severity of prostate cancer, supporting the influence of adipokine pathways in the pathogenesis of prostate cancer. Use of such adipokine multilocus genetic risk score can enhance the predictive value of PSA and age in estimating absolute risk, which supports further evaluation of its clinical significance.

Association between endometriosis and polymorphisms in insulin-like growth factor binding protein genes in Korean women

OBJECTIVE

Genetic factors are known to be associated with the development and progression of endometriosis, but the genes related to endometriosis have not been defined. Insulin-like growth factor binding proteins (IGFBPs) are believed to be involved in the proliferation and apoptosis of cells that play an important role in the pathophysiologic mechanism of endometriosis. This study aimed to determine the association between endometriosis and polymorphisms of the IGFBP genes in Korean women.

STUDY DESIGN

In a case-control study, the rs1995051, rs1065780 and c.759A>G single nucleotide polymorphisms (SNPs) in the IGFBP1 gene and the -672A>G, -202A>C and c.95C>G SNPs in the IGFBP3 gene were analyzed in 128 women with endometriosis and 108 normal control women.

RESULTS

The haplotype genotype composed of a combination of three IGFBP1 gene polymorphisms was not related to endometriosis, while the haplotype genotype of the IGFBP3 gene had a significant association with endometriosis. Women not carrying the AAG (-672A/-202A/c.95G) haplotype allele of three IGFBP3 gene polymorphisms have a 3.19-times higher risk of endometriosis compared with women with AAG homozygotes, and this trend was found in women with advanced endometriosis but not in women with early endometriosis.

CONCLUSIONS

The AAG haplotype allele of the -672A>G, -202A>C and c.95C>G polymorphisms in the IGFBP3 gene may be associated with advanced endometriosis in Korean women.

Targeting the insulin-like growth factor receptor pathway in lung cancer: problems and pitfalls

The insulin-like growth factor (IGF) pathway is a complex pathway involving interactions between membrane-bound receptors, ligands, binding proteins, downstream effectors, and other receptor tyrosine kinase signaling cascades. The IGF pathway has been identified as a potential therapeutic target in non-small cell lung cancer (NSCLC) based on the following provocative factors. Preclinical observations in NSCLC have shown that this pathway is involved in tumor cell proliferation, survival, and invasiveness. In addition, IGF-1R protein expression is found in a significant number of non-small cell tumor specimens. Initial therapeutic efforts involved the development of monoclonal antibodies and tyrosine kinase inhibitors that target IGF-1R, a transmembrane receptor tyrosine kinase. Enthusiasm for targeting this pathway increased when a randomized phase II study showed that combining an anti-IGF-1R monoclonal antibody (figitumumab) with a platinum doublet resulted in a higher response rate and trends for superior progression-free survival and overall survival. Subsequently, a phase III study failed to confirm the promising results observed in the phase II trial. Currently, investigators are studying different monoclonal antibodies and tyrosine kinases targeting IGF-1R. In unselected patients, results presented thus far do not suggest efficacy of this agent. However, retrospective subgroup analyses suggest that circulating IGF-1 levels might identify patients who could benefit from treatment with an IGF-1R monoclonal antibody and may warrant further exploratory studies for predictive molecular markers. The purpose of this paper is to briefly discuss the IGF pathway and its relationship with other signaling pathways in lung cancer and to review the ongoing IGF clinical trials and efforts to identify predictive molecular markers.

The Arg194Trp polymorphism in the XRCC1 gene and cancer risk in Chinese Mainland population: a meta-analysis

The Arg194Trp polymorphism in the X-ray repair cross-complementing group 1 (XRCC1) gene has been proved to be in association with cancer risk in Chinese Mainland population, but a large number of studies have reported inconclusive results. A more comprehensive and precise estimation of the relationship is needed to clear the way towards future studies. Thus, we performed a meta-analysis to analysis these associations. A total of 34 case-control studies in 34 articles were included in this meta-analysis. The results showed that the 194Trp/Trp homozygote had a 31% increased risk of cancer than 194Trp/Arg and 194Arg/Arg genotypes, OR was 1.31 and 95%CI was 1.13 to 1.53. In the subgroup analysis by cancer sites, the Arg194Trp polymorphism was associated with increased risks of lung cancer (OR = 1.27 and 95%CI: 1.07-1.50 for Trp/Trp versus Arg/Arg + Arg/Trp) and esophageal cancer (OR = 1.68 and 95%CI: 1.33-2.13 for Trp/Trp versus Arg/Arg + Arg/Trp). This meta-analysis suggested that the Arg194Trp polymorphism of the XRCC1 gene is a cancer susceptible factor among Chinese Mainland population. More intensive and deeper studies are needed to further reveal the mechanism between Arg194Trp polymorphisms of XRCC1 gene and cancer risks in Chinese Mainland population.

Cyclin D1 G870A polymorphism and breast cancer risk: a meta-analysis comprising 9,911 cases and 11,171 controls

Cyclin D1 represents a key molecule in the regulation of cell cycle. CCND1 G870A (rs603965) polymorphism has drawn considerable attention as the A allele may generate a variant splice product with possible oncogenic actions. A meta-analysis examining the association between CCND1 G870A polymorphism and breast cancer risk was performed. Separate analyses on Caucasian and Chinese populations were also implemented. Eligible articles were identified for the period up to July 2010. Pooled odds ratios (OR) were appropriately derived from fixed-effects or random-effects models. Sensitivity analysis excluding studies whose genotype frequencies in controls significantly deviated from Hardy-Weinberg Equilibrium (HWE) was performed. Nine case-control studies on Caucasians (7,304 cases and 8,149 controls) and four case-control studies on Chinese (2,607 cases and 3,022 controls) were eligible. At the overall analysis the A allele seemed to be associated with elevated breast cancer risk; the effect seemed to be confined to homozygous carriers (pooled OR = 1.091, 95% CI: 1.008-1.179, P = 0.030, fixed effects) as heterozygous carriers did not exhibit significantly elevated breast cancer risk. No statistically significant associations were demonstrated in Caucasians. On the other hand, Chinese AA carriers exhibited marginally elevated breast cancer risk (pooled OR = 1.144, 95% CI: 0.984-1.329, P = 0.080, fixed effects). Nevertheless, the controls in two out of the four Chinese studies deviated from HWE. In conclusion, this meta-analysis suggests that the A allele of the CCND1 G870A polymorphism may confer additional breast cancer risk when it comes to homozygosity and Chinese populations. The need for additional, methodologically sound studies on Chinese populations seems warranted.

Serum insulin-like growth factor I (IGF-I), IGF-binding proteins 2 and 3, and the risk for development of malignancies in adults with growth hormone (GH) deficiency treated with GH: data from KIMS (Pfizer International Metabolic Database)

CONTEXT

The association between IGFs and cancer in adults with GH deficiency (GHD) receiving GH replacement requires investigation.

OBJECTIVE

The objective was to examine the association between IGF-I, IGF-binding protein 2 (IGFBP-2), and IGFBP-3 SD scores (SDSs) in GH-deficient adults receiving GH therapy and the occurrence of de novo malignancies.

DESIGN

Serum IGF-I, IGFBP-2, and IGFBP-3 levels in GH-deficient patients who developed a malignancy since receiving GH were compared with patients with idiopathic GHD but without malignancy. Measurements were related to age-, sex-, and body mass index-specific SDS reference regions.

SETTING

The setting included the KIMS (the Pfizer International Metabolic Database).

PATIENTS

One hundred patients with de novo malignancy during GH therapy were compared with 325 patients with idiopathic GHD without malignancy.

INTERVENTION(S)

Serum samples were obtained as close as possible to the diagnosis of malignancy, or after approximately 2 yr of GH replacement in KIMS.

MAIN OUTCOME MEASURES

Associations between relative risk (RR) of malignancy and IGF-I, IGFBP-2, and IGFBP-3 SDSs were assessed in multiple log-linear Poisson working regression models, controlling for age, sex, onset of GHD, and GH naivety at KIMS entry.

RESULTS

No association between IGF-I SDSs and RR was observed (P = 0.48). Increasing IGFBP-2 and IGFBP-3 SDSs were associated with increasing RRs [18% per unit IGFBP-2 SDSs (95% confidence interval, 7-30%; P = 0.0006), 13% per unit IGFBP-3 SDS (2-26%; P = 0.01)].

CONCLUSIONS

IGF-I levels targeted to within normal age-related reference ranges during GH replacement were not associated with the occurrence of malignancies. Higher IGFBP-2 and/or IGFBP-3 SDSs may be associated with increased cancer risk.

TNF-308 gene polymorphism is associated with COPD risk among Asians: meta-analysis of data for 6,118 subjects

Chronic obstructive pulmonary disease (COPD) is a complex polygenic disease in which gene-environment interactions play a critical role in disease onset and progression. The gene encoding tumor necrosis factor (TNF) is one of several candidate loci for the pathogenesis of COPD and is highly polymorphic. A number of studies have investigated the association between the TNF-308 polymorphisms and COPD risk in different populations, and resulted in inconsistent results. A systematic review and meta-analysis of the published studies were performed to gain a clearer understanding of this association. The PubMed, Embase, Web of Science, and CNKI databases were searched for case-control studies published from 1966 to April 2009. Data were extracted and pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated. Twenty-four eligible studies, comprising 2,380 COPD cases and 3,738 controls, were included in the meta-analysis. The pooled result showed that the TNF-308 polymorphisms were significantly associated with an increased risk of COPD (OR=1.335, 95% CI: 1.172-1.522, for allele A carriers versus G/G; OR=1.330, 95% CI=1.174-1.505, for allele A versus allele G). Subgroup analysis supported the results in the Asian populations, but not in the Caucasian populations. When the analysis was limited to only those studies in which the COPD cases and controls were smokers/ex-smokers, the pooled results supported the conclusion. This meta-analysis suggested that the TNF-308 A allele is a more significant risk factor for developing COPD among Asian populations, but not among Caucasians.

ARLTS1, MDM2 and RAD51 gene variations are associated with familial breast cancer

Genetic factors that contribute to the risk of breast cancer are largely not known and association studies have revealed several genes with low penetrance risk alleles for breast cancer. Analysis of these genes may provide important information on the risk factors affecting carcinogenesis. Variations in the ARLTS1, RAD51 and MDM2 genes have been associated with increased risk of different cancer types but for breast cancer the results are not consistent. In this study we investigated the role of the allelic variants in candidate genes acting in the tumor suppressor, DNA repair and p53 pathways as risk factors for familial breast cancer in 147 patients displaying characteristics of familial disease. Presence of the polymorphic variants were investigated by amplification of the corresponding regions and restriction fragment length polymorphism analysis. Genotype and allele frequencies in the patients were significantly different for all three variants. Our results indicate that the polymorphic variants might affect individual susceptibility towards breast cancer.