By David Liu, PHD

Monday Aug 27, 2012 (foodconsumer.org) -- Phthalates, a group of chemicals that are typically used to make soft plastic, have been known to pose a risk as an estrogen to public health including breast cancer and prostate cancer.   A new study in the FASEB Journal has found evidence to suggest that these chemicals can also promote breast cancer through another pathway without estrogen involved.

The study was intended to examine how phthalates affect hormone-dependent breast cancer risk. And the results showed that estrogen receptor-negative breast cancer cells exposed to phthalates namely n-butyl benzyl phthalate (BBP) and dibutyl phthalate (DBP) increased proliferation, migration, invasion and tumor formation.

Specifically, in estrogen receotir negative breast cancer cells, treatments with the two named phthalates at 1 μM increased proliferation by more than 3 times, migration by 2.6 times, invasion by at least 2.7 times, and tumor formation by at least 0.12 um.

Tsung-Hua Hsieh of Kaohsiung Medical University in Kaohsiung, Taiwan and colleagues, the study authors, further demonstrated 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."

They said in their report that "This nongenomic pathway emanated from the phthalate-induced AhR promoted tumorigenesis of ER-negative breast cancer."  and concluded "Collectively, our findings revealed a novel oncogenic mechanism of phthalates in breast cancer independent from their estrogenic activities."