Murine double minute clone 2,309T/G and 285G/C promoter single nucleotide polymorphism as a risk factor for breast cancer: a Polish experience.

BACKGROUND: Breast cancer is a multifactorial disease caused by complex interactions between genetic and environmental factors. Recently, a functional polymorphism, MDM2 285G>C (rs117039649), has been discovered. This polymorphism antagonizes the effect of the 309T>G (rs2279744) polymorphism on the same gene, resulting in decreased MDM2 transcription. METHODS: The MDM2 285G>C and 309T>G polymorphisms were identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing analysis in women with breast cancer (n=468) and controls (n=550). RESULTS: The odds ratio (OR) for breast cancer patients with the MDM2 285C/C and 285G/C genotypes was 0.4768 (95% confidence interval [CI] 0.2906-0.7824; p=0.0033, pcorr=0.0066). We also found a significantly lower frequency of the MDM2 285C allele in patients with breast cancer than in controls: the OR for the C allele in patients with breast cancer was 0.4930 (95% CI=0.3059-0.7947, p=0.0031, pcorr=0.0062). The p value of the chi-square test for the trend observed for the MDM2 285G>C polymorphism was statistically significant (ptrend=0.0036). The statistical power of this study amounted to 85% for the G/C or C/C genotypes and 85% for the C allele. However, we did not observe significant differences between the distribution of MDM2 309T>G genotypes and alleles in patients with breast cancer and healthy controls. CONCLUSION: In a sample of the Polish population, we observed that the MDM2 285C gene variant may be a significant protective factor against breast cancer.

CCL2 -2518 A/G single nucleotide polymorphism as a risk factor for breast cancer.

The contribution of the CCL2 -2518 A>G (rs 1024611) polymorphism in the occurrence and progression of various cancers has been found to be discordant. We studied the prevalence of the CCL2 -2518 A>G polymorphism in patients with breast cancer (n = 160) and controls (n = 323) in a sample of the Polish population. There were no significant differences in CCL2 -2518 A>G genotypes between patients with breast tumors and controls. Odds ratio (OR) for patients bearing the GG genotype was 1.481 (95% CI = 0.7711-2.845, P = 0.2358), and OR of the GG and AG genotypes was 0.7269 (95% CI = 0.4967-1.064, P = 0.1002). There was also no significant distinction in the prevalence of alleles between patients and healthy individuals. OR for the CCL2 -2518 G allele frequency was 0.8903 (95% CI = 0.6611-1.199, P = 0.4441). Analysis of the association between tumor size, lymph node metastases, histological grade, and distribution of genotypes and alleles for the CCL2 -2518 A>G polymorphism also did not show significant differences. Our results did not show association of the CCL2 -2518 A>G polymorphism with breast cancer occurrence and clinical characteristics in a sample of the Polish cohort.

Phytosterols in physiological concentrations target multidrug resistant cancer cells.

Phytosterols have been proposed to act as potent anticancer agents. However the mechanism of their action has not been elucidated yet. Thus, the aim of our study was to determine whether plant sterols and their thermal processing products (in physiological concentration range) could influence the viability of cancer cells and thus could be considered as positive diet complements. Additionally we decided to study potential specificity of those natural compounds against cells showing high multidrug resistance. In this study we show that the cytotoxic effect of ß-sitosterol was observed in both, estrogen-dependent and estrogen-independent cells. It was also shown that the ß-sitosterol was significantly more cytotoxic in cells with basal ABCB1 expression (MCF7) than in multidrug resistant NCI/ADR-RES. Surprisingly, 5a,6a-epoxysitosterol did not decrease the viability of any investigated cells but on the contrary, it provoked their increased proliferation. It was shown that oxyphytosterols blocked the cell cycle of MCF7 cells in G0/G1 phase while did not affect NCI/ADR-RES cell cycle in physiological concentration range. We also show that PgP activity (responsible for Multidrug Resistance phenomena) is inhibited by ß-sitosterol. Thus, the phytosterols are supposed to act at various mechanisms but, what is most interesting, can target cells showing high multidrug resistance potential.

CXCL12-3' G801A polymorphism is not a risk factor for breast cancer.

The CXCL12-3' G801A transition (rs1801157) has been associated with the incidence of breast cancer. However, the contribution of CXCL12-3' G801A polymorphisms in breast cancer development and progression has been controversial. Therefore, we examined the incidence of CXCL12-3' G801A polymorphic variants in patients with breast cancer (n = 193) and controls (n = 199) in a Polish cohort. We observed a trend of slightly increased presence of CXCL12-3' AA and GA genotypes and CXCL12-3'A allele frequency in patients with breast cancer compared with healthy individuals. However, these differences between cases and controls were not statistically significant. Odds ratio (OR) for patients with breast cancer and the CXCL12-3' A/A genotype was 1.898 (95% confidence interval [CI] = 0.6242-5.770, p = 0.2866) and OR of the CXCL12-3' A/A and A/G genotypes was 1.229 (95% CI = 0.8082-1.868, p = 0.3395). OR for the CXCL12-3'A allele frequency was 1.249 (95% CI = 0.8716-1.789, p = 0.2352). Our investigation did not support the CXCL12-3'A gene variant as a risk factor for breast cancer incidence in a sample of the Polish population.