Melanoma cells undergo aggressive coalescence in a 3D Matrigel model that is repressed by anti-CD44

Abstract

Using unique computer-assisted 3D reconstruction software, it was previously demonstrated that tumorigenic cell lines derived from breast tumors, when seeded in a 3D Matrigel model, grew as clonal aggregates which, after approximately 100 hours, underwent coalescence mediated by specialized cells, eventually forming a highly structured large spheroid. Non-tumorigenic cells did not undergo coalescence. Because histological sections of melanomas forming in patients suggest that melanoma cells migrate and coalesce to form tumors, we tested whether they also underwent coalescence in a 3D Matrigel model. Melanoma cells exiting fragments of three independent melanomas or from secondary cultures derived from them, and cells from the melanoma line HTB-66, all underwent coalescence mediated by specialized cells in the 3D model. Normal melanocytes did not. However, coalescence of melanoma cells differed from that of breast-derived tumorigenic cell lines in that they 1) coalesced immediately, 2) underwent coalescence as individual cells as well as aggregates, 3) underwent coalescence far faster and 4) ultimately formed long, flat, fenestrated aggregates that were extremely dynamic. A screen of 51 purified monoclonal antibodies (mAbs) targeting cell surface-associated molecules revealed that two mAbs, anti-beta 1 integrin/(CD29) and anti-CD44, blocked melanoma cell coalescence. They also blocked coalescence of tumorigenic cells derived from a breast tumor. These results add weight to the commonality of coalescence as a characteristic of tumorigenic cells, as well as the usefulness of the 3D Matrigel model and software for both investigating the mechanisms regulating tumorigenesis and screening for potential anti-tumorigenesis mAbs.

Three-dimensional experiments and individual based simulations show that cell proliferation drives melanoma nest formation in human skin tissue

“…Our results are different to previous 3D studies that show melanoma nests are formed by cell migration [5]. We anticipate that the difference in our outcome could be due to: (i) differences between the melanoma cell lines used; (ii) the interaction of melanoma cells with the surrounding skin cells in our 3D experiments; or, (iii) differences in the material used to construct the 3D model.…”

“…Recent 3D experimental work by Wessels et al . [5] suggests that melanoma nest formation in Matrigel is driven by cell migration. However, nest formation might be different in human skin, where melanoma cells are in contact with other cell types [1,6].…”

Integrin α-3 ß-1’s central role in breast cancer, melanoma and glioblastoma cell aggregation revealed by antibodies with blocking activity

“…Tumors form in a 3D environment Therefore, in vitro studies of cancer cell behavior should be performed in a 3D model. [1][2][3] We recently reported that both tumorigenic cell lines and fresh tumor cells, when dispersed in a transparent 3D Matrigel environment, divide and undergo directed, cell-mediated cell aggregation and aggregate coalescence ("aggregation and coalescence"). [1][2][3] Non-tumorigenic cell lines and normal cell cultures derived from non-cancerous tissue, do not exhibit these behaviors.…”

“…[1][2][3] We recently reported that both tumorigenic cell lines and fresh tumor cells, when dispersed in a transparent 3D Matrigel environment, divide and undergo directed, cell-mediated cell aggregation and aggregate coalescence ("aggregation and coalescence"). [1][2][3] Non-tumorigenic cell lines and normal cell cultures derived from non-cancerous tissue, do not exhibit these behaviors. [1][2][3] In time, large aggregates formed by tumorigenic cells assume forms consistent with the tumors formed in vivo.…”

“…[1][2][3] Non-tumorigenic cell lines and normal cell cultures derived from non-cancerous tissue, do not exhibit these behaviors. [1][2][3] In time, large aggregates formed by tumorigenic cells assume forms consistent with the tumors formed in vivo. [1][2][3] Previously, we demonstrated that the anti-integrin ß-1 monoclonal antibody (mAb), AIIB2, 4 blocked aggregation and coalescence in a 3D Matrigel environment, 1 in the tumorigenic cell line MDA-MB-435-α6HG6, which was derived from a breast cancer.…”