No abstract

The environmentally present group of chemical phthalates, or phthalate esters, has been recognized as a rising threat to public health, including cancer. While most studies have addressed the estrogenic effects of phthalates in malignancies of the breast and the prostate, little is known about their role in the etiology of hormone-independent cancer. Here we show that treatments with the phthalates n-butyl benzyl phthalate (BBP) and dibutyl phthalate (DBP) at 1 μM induced proliferation (BBP, 3.2-fold; DBP, 3.2-fold), migration (BBP, 2.6-fold; DBP, 2.6-fold), invasion (BBP, 2.7-fold; DBP, 3.1-fold), and tumor formation (EC(50): BBP, 0.12 μM; DBP, 0.22 μM) in estrogen receptor (ER)-negative breast cancer cells (MDA-MB-231). We further demonstrate that phthalates stimulated the cell surface aryl hydrocarbon receptor (AhR) and triggered the downstream cyclic AMP (cAMP)-PKA-CREB1 signaling cascade. The pathway led to increased expression of HDAC6, which facilitated nuclear assembly of the β-catenin-LEF1/TCF4 transcriptional complex and transactivation of the c-Myc oncogene. This nongenomic pathway emanated from the phthalate-induced AhR promoted tumorigenesis of ER-negative breast cancer. Collectively, our findings revealed a novel oncogenic mechanism of phthalates in breast cancer independent from their estrogenic activities.

It is believed that endometrial miRNAs contribute to the aetiology of endometriosis in stem cells; however, the mechanisms remain unclear. Here we collected serum samples from patients with or without endometriosis and characterized the miRNA expression profiles of these two groups. MicroRNA-199a-5p (miR-199a-5p) was dramatically down-regulated in patients with endometriosis compared with control patients. In addition, we found that the tumour suppressor gene, SMAD4, could elevate miR-199a-5p expression in ectopic endometrial mesenchymal stem cells. Up-regulation of miR-199a-5p suppressed cell proliferation, motility and angiogenesis of these ectopic stem cells by targeting the 3' untranslated region of VEGFA. Furthermore, we established an animal model of endometriosis and found that miR-199a-5p could decrease the size of endometriotic lesions in vivo. Taken together, this newly identified miR-199a-5p module provides a new avenue to the understanding of the processes of endometriosis development, especially proliferation, motility and angiogenesis, and may facilitate the development of potential therapeutics against endometriosis.

Identifying stably expressed tumor markers that can be used easily to detect cancer is currently an important area of cancer research. By using miRNA microarray, we identified 20 differentially expressed miRNAs in serum samples of breast cancer patients. Expression of miR-125a-5p was relatively lower in patients with shorter survival compared to long-term survivors. In a cohort of breast cancer patients (N = 300), serum expression of miR-125a-5p was negatively and significantly correlated with tumor grade (P = 0.004), lymph-node status (P = 0.004), and tumor size (P < 0.001). Low miR-125a-5p expression was an independent prognostic marker (OR = 0.421; 95% CI = 0.184 to 0.961; P = 0.04) associated with poor survival rates (P = 0.0062). We show that miR-125a-5p directly inhibits expression of the HDAC4 gene, resulting in tumor suppression in vitro and in vivo. Together these results demonstrate that serum miR-125a-5p level in breast cancer may be a useful prognostic biomarker and offer a novel therapeutic avenue by targeting HDAC4 in breast cancer.