Genetic variation in multiple biologic pathways, flavonoid intake, and breast cancer

Flavonoid calycopterin triggers apoptosis in triple-negative and ER-positive human breast cancer cells through activating different patterns of gene expression

Breast cancer is the most common cause of death related to cancer in women, and several studies proved that flavonoids could induce apoptosis in this cancer through different pathways. Calycopterin is a flavonoid which was shown to induce preferential antiproliferative effects on some cancers; however, no information is available on its effect on breast cancer. Therefore, in this paper, the apoptotic effect of calycopterin and its underlying mechanism in two different breast cancer cells, MDA-MB-231 and MCF7 cell lines were investigated. MTT assay showed that calycopterin reduced the proliferation of both cancer lines with no adverse effect on normal cells. The clonogenic assay showed that calycopterin treatments decreased the colony numbers and sizes, and wound healing assay demonstrated the inhibition of migration in both cancer cells. Cell cycle and annexin/PI analyses indicated that calycopterin augmented sub-G1 population and annexin/PI-positive cells. Gene expression revealed that Bax/Bcl2 increased in the MDA-MB-231 cell line, while no change was observed in that of the MCF7 line. Expression of gene caspase-8 was augmented in both lines, although increased expression of caspase-3 was found just in MDA-MB-231 cells. Our results validated the apoptotic effect of calycopterin on both breast cancer lines with more potency on triple-negative ones.

Epidemiological Evidences on Dietary Flavonoids and Breast Cancer Risk: A Narrative Review

Epidemiological studies on associations between intake of flavonoids and breast cancer risk are highly needed to assess the actual effects of flavonoids in humans. Experimental investigations in vitro conditions cannot detect and model the real action of these phytochemicals due to the limitations to consider absorption and metabolic biotransformation as well as several complex interactions. Therefore, the data about association findings between intake of flavonoids and breast cancer risk are compiled and analyzed in the current review by evaluating both the results obtained using food composition databases as well as different biomarkers. Although several case-control studies demonstrate some reduction in breast cancer risk related to high consumption of flavones and flavonols, large-scale prospective cohort studies with follow-up times of many years do not confirm these findings. Intake of isoflavones can be associated with a decrease in breast tumorigenesis only in Asian countries where the consumption of soy foods is high but not among Western women with significantly lower ingestion amounts, suggesting the presence of so-called threshold level of effect. Besides doses, the timing of exposure to isoflavones seems also to be a significant factor as childhood and prepubertal age can be critical periods. Although women may need to consume high amounts of isoflavones typical to Asian diets to gain beneficial effects and protection against mammary carcinogenesis, it is still too early to give any specific recommendations to prevent breast tumors by diet rich in certain flavonoids.

Delphinidin-3-glucoside suppresses breast carcinogenesis by inactivating the Akt/HOTAIR signaling pathway

BACKGROUND

The long non-coding RNA (lncRNA) HOX transcript antisense RNA (HOTAIR) plays a crucial role in cancer progression, which is regulated by the interferon regulatory factor-1 (IRF1) and up-streaming Akt activation. The present study evaluated the chemopreventive effects of delphinidin-3-glucoside (Dp), a major anthocyanin present in pigmented fruits and vegetables, on breast carcinogenesis, and investigate the role of the Akt/HOTAIR signaling pathway.

METHODS

Human breast epithelial cells MCF10A were treated with carcinogens (NNK and B[a]P) or co-treated with carcinogens plus Dp for 30 days. Then, the cancer-associated properties of the treated cells were evaluated to assess the carcinogenesis and the effects of Dp. HOTAIR levels were detected by qRT-PCR. The proteins expression was measured by western blots, immunofluorescence and immunohistochemistry. Xenografted tumors were made by implanting breast cancer cells MDA-MB-231-Luc-GFP in athymic mice. ChIP-qPCR analysis was used to detect the IRF1 binding to the HOTAIR promoter.

RESULTS

Carcinogens treatment induces apparent carcinogenic transformation in MCF10A cells including reduced dependence on growth factors, anchorage-independent cell growth and aberrant wound-healing ability, which is effectively suppressed by Dp co-treatment. The level of HOTAIR significantly increases in a time-dependent manner during chronic breast carcinogenesis. Dp treatment down-regulates HOTAIR expression in breast carcinogenesis and breast cancer cells. Furthermore, Dp administration inhibits the growth of xenografted breast tumors in athymic mice, and decreases HOTAIR in vivo. Further studies showed that Dp represses Akt activation, promotes IRF1 expression and increases IRF1 binding to the HOTAIR promoter. Silence of IRF1 expression via transfecting cells with IRF1 siRNAs significantly reduced the effects of Dp on HOTAIR, resulting in decreased cytotoxic effects of Dp on breast cancer cells.

CONCLUSIONS

These data suggest the effective chemopreventive effect of Dp on breast carcinogenesis, in which down-regulation of HOTAIR plays a critical role.

Polymorphism of cytosolic serine hydroxymethyltransferase and breast cancer risk: evidence from a meta-analysis

One-carbon metabolism has been presumed to influence cancer pathogenesis. Cytosolic serine hydroxymethyltransferase (cSHMT) is a critical enzyme in one-carbon metabolism pathway. Until now, many studies have investigated the association between cSHMT (also named SHMT1) C1420T polymorphism and breast cancer risk. However, the results remained conflicting rather than conclusive. Literature search was conducted using PubMed, Embase, and China National Knowledge Infrastructure (CNKI) databases until December 2013 to identify studies investigating the association of SHMT1 C1420T polymorphism with breast cancer risk. The strength of the association was assessed by the summary odd ratios (ORs) and their corresponding 95 % confidence interval (CI). Seven studies with a total of 5,534 cases and 6,581 controls were included. Overall, no association was detected between SHMT1 C1420T polymorphism and breast cancer risk (T vs. C, OR = 0.97, 95 % CI = 0.92-1.03). In the subgroup analysis based on ethnicity, SHMT1 C1420T polymorphism has shown a protective effect on breast cancer in Asians (T vs. C, OR = 0.78, 95 % CI = 0.66-0.93) but not in Caucasian (T/T vs. C/C, OR = 0.98, 95 % CI = 0.86-1.12). Significant heterogeneity across studies could be observed in some genetic comparison models in the overall estimation (C/T vs. C/C, P het = 0.004; T/T+C/T vs. C/C, P het = 0.006) but turned to be mild in all comparison models when stratified by ethnicity. Our meta-analysis failed to detect association between SHMT1 C1420T polymorphism and breast cancer risk. However, we found evidence for association of SHMT1 C1420T polymorphism with significantly reduced risk of breast cancer in Asians. Further well-designed studies with larger sample size and better selected controls are warranted.