A Polycyclic Aromatic Hydrocarbon Environmental Chemical Mixture Increases Growth of Inflammatory Breast Cancer Tumor Emboli

Exposure to polycyclic aromatic hydrocarbon (PAH) chemicals is widespread due to their presence in emissions from tobacco smoke, wood stoves, and organic fuel burning throughout the world. Many PAHs are classified as carcinogens, and prior studies have shown an increase proliferation in an estrogen-receptor positive human breast adenocarcinoma cell line due to exposure to low doses of a complex PAH mixture. The objective of this study was to observe the effects of the same PAH chemical mixture on an aggressive human inflammatory breast cancer cell line using a 3D tumor emboli assay. We hypothesized that greater concentrations of PAH mixture would lead to greater tumor emboli growth. Cells were seeded in ultra-low attachment well plates and once emboli were formed, they were treated with different concentrations of PAH mixture, called Elizabeth River Sediment Extract (ERSE). Microscopic and statistical analysis revealed that low nanomolar doses of ERSE result in greater tumor emboli size compared to untreated emboli, in a dose-dependent manner. There was a positive correlation between emboli size and increased ERSE concentration, although a high micromolar ERSE dose was cytotoxic to the cells. Collectively, these results suggest that low-dose exposure to this PAH mixture can enhance growth of aggressive breast cancer cells, and may have a wider and more substantial impact on cancer progression and outcome.

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