Researchers from The University of Zurich and The University of Brescia, Italy have demonstrated the ability of U94, the latency gene for the human herpesvirus 6, to interfere with the metastatic potential of MDA-MB 231 (breast cancer) and HeLa (cervical cancer) cell lines.

Synthecon’s RCCS bioreactor was used to form MDA-MB231 and HeLa tumor spheroids. In separate experiments, both cell lines were placed in dynamic 3D culture for 2 days, which organized the cells into biomimetic 3D microenvironments, typical of tumors found in vivo. Cells were harvested and processed for staining, as well as prepared for rt-PCR analysis for mesenchymal markers. See above image, Figure 4, Oncotarget 2017.

U94 was delivered to the cell populations via an HSV-1 amplicon which promoted “down modulation of of Src and other downstream molecules linked to cell motility and proliferation.” Caccuri et al 2017. Further, U94 was able to inhibit cell growth, invasion and metastasis to target these cell lines in the RCCS.

The Synthecon bioreactor platform, allowed the researchers to form and mature tumor spheroids, (cells which were previously transduced cells by the U94 amplicon via titration). The 3D bioreactor provided environmental conditions to generate biologically relevant tissue which had been exposed to the therapeutic method of interest (U94), in order to stifle metastasis. When assessed for metastatic potential including inhibition of migratory activity of these cells and markers for the ability to invade other tissues, cells cultured in the RCCS showed similar and comparable results to the in-vivo experiments performed as part of this study.  

The U94+ cells experienced a significant reduction in cell proliferation over the course of the 9 day experiment over non-treated and positive control (EGFP+) cells. Western blot analysis of cell lysates demonstrated the down-modulating effect of U94 on MDA-MB 231 cells, via a dramatic decrease in pSrc levels compared to control cells, in addition to downstream molecules linked to motility, invasion and proliferation.

Finally, to ensure that the RCCS had accurately modeled these functions, tumor progression was analyzed in NOD/SCID mice injected with the UP94 transformed cells. 23 days post injection, the tumors were excised and compared to the non- treated and EGFT+ control groups. U94+ tumors weighed significantly less (2-3X), and showed weak cytoplasmic expression of vimentin as compared to the controls.

Paramount to the aggressive spread of conditions such as breast and cervical cancer is ability of tumor cells to aggregate, invade and cross tissue barriers which are normally non-permeable to foreign cell types. The authors describe, EMT, the ability of epithelial cancer cells to transition into mesenchymal-like elements, as essential to metastasis and further spread throughout the body.

Key Points

• The RCCS allowed for in vitro demonstration of viral element therapeutic targeting of two breast and cervical cancer lines.

• Only 48 hours to model tumors and show inhibition of tumor formation in the RCCS. 

• RCCS is a key platform to study tumor formation and therapeutic targeting.