Paracrine interaction in co-culture of hormone-dependent and independent breast cancer cells

Impact of Chemotherapeutic Stress Depends on The Nature of Breast Cancer Spheroid and Induce Behavioral Plasticity to Resistant Population

Cellular or tumor dormancy, identified recently as one of the main reasons behind post-therapy recurrence, can be caused by diverse reasons. Chemotherapy has recently been recognized as one of such reasons. However, in-depth studies of chemotherapy-induced dormancy are lacking due to the absence of an in vitro human-relevant model tailor-made for such a scenario. This report utilized multicellular breast cancer spheroid to create a primary platform for establishing a chemotherapy-induced dormancy model. It is observed that extreme chemotherapeutic stress affects invasive and non-invasive spheroids differently. Non-invasive spheroids exhibit more resilience and maintain viability and migrational ability, while invasive spheroids display heightened susceptibility and improved tumorigenic capacity. Heterogenous spheroids exhibit increased tumorigenic capacity while show minimal survival ability. Further probing of chemotherapeutically dormant spheroids is needed to understand the molecular mechanism and identify dormancy-related markers to achieve therapeutic success in the future.

Three dimensional multicellular co-cultures and anti-cancer drug assays in rapid prototyped multilevel microfluidic devices

This report presents a multilevel microfluidic platform for robust construction of hydrogel scaffold in microchannels and its application to three dimensional (3D) multicellular co-cultures and assays. A new rapid prototyping method based on soft lithography using multi-layered adhesive tapes is also introduced. We have successfully cultured MCF-7 breast cancer cell line more than 11 days with > 98 % viability, and co-cultured MDA-MB-231 breast cancer cells and NIH/3T3 fibroblasts in separate compartments. This multilevel microfluidic device with a cell-laden hydrogel microstructure has also been applied for anticancer drug assays in multicellular niches. Here we tested the effect of estrogen receptor (ER) antagonist drug, tamoxifen, on the growth of ER positive MCF-7 cells in microchannels. The inhibitory effect of tamoxifen on the growth of MCF-7 cells was diminished when they were co-cultured with ER negative MDA-MB-231 cells. The rapid prototyped multilevel microfluidic devices would provide simple, easy to use, low cost, robust, and reproducible cell-based assay platforms for potential end-users such as biologists and pharmacists.

The two phyto-oestrogens genistein and quercetin exert different effects on oestrogen receptor function

We compared the oestrogenic and anti-oestrogenic properties of the two well-known phyto-oestrogens, genistein and quercetin, on the oestrogen-sensitive breast cancer cell line MCF-7. Genistein exerted a biphasic effect on growth of MCF-7 cells, stimulating at low and inhibiting at high concentrations, whereas quercetin was only growth inhibitory. At doses which did not inhibit cell growth, respectively 5 and 1 microM, genistein and quercetin counteracted oestrogen- and transforming growth factor-alpha-promoted cell growth stimulation. Furthermore, genistein promoted transcription of the oestrogen-regulated genes pS2 and cathepsin-D, whereas quercetin interfered with the oestrogen-induced expression of the proteins. In in vitro binding experiments, genistein competed with oestradiol for binding to the oestrogen receptor (ER), but quercetin did not. Quercetin and genistein down-regulated cytoplasmic ER levels and promoted a tighter nuclear association of the ER, but only genistein was able to up-regulate progesterone receptor protein levels. In gel mobility assays, ER preincubation with oestradiol or with the two phyto-oestrogens led to the appearance of the same retarded band, excluding differences between the various complexes in binding to the consensus sequence. The data allowed us to conclude that quercetin acts like a pure anti-oestrogen, whereas genistein displays mixed agonist/antagonist properties, and to formulate a hypothesis on the possible mechanism of action of such phyto-oestrogens.

Genistein in the control of breast cancer cell growth: insights into the mechanism of action in vitro

Genistein significantly inhibited cell growth (IC50 around 10 microM) of MCF-7, MDAMB-231 and HBL-100 cell lines, but not of skin-derived fibroblasts and counteracted the growth-stimulatory effects exerted by estradiol and growth factors. It abolished the paracrine stimulation observed in MCF-7 cells in co-culture with MDAMB-231 or fibroblasts. Genistein-treated cells accumulated in the S and G2/M phases of the cell cycle and underwent apoptosis. Genistein decreased tyrosine phosphorylation induced upon treatment with transforming growth factor-alpha. Finally, genistein bound the estrogen receptor (ER) (relative affinity constant Kd = 4 nM), induced pS2 and cathepsin-D transcription and increased nuclear ER levels.