Quantifying rates of cell migration and cell proliferation in co-culture barrier assays reveals how skin and melanoma cells interact during melanoma spreading and invasion

Parvathi Haridas,Catherine J Penington,Jacqui A Mcgovern,D.L Sean Mcelwain,Matthew J Simpson

doi:10.1016/j.jtbi.2017.04.017

Parvathi Haridas, Catherine J Penington + Show 3 more

Open Access

https://doi.org/10.1016/j.jtbi.2017.04.017

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Abstract

Malignant spreading involves the migration of cancer cells amongst other native cell types. For example, in vivo melanoma invasion involves individual melanoma cells migrating through native skin, which is composed of several distinct subpopulations of cells. Here, we aim to quantify how interactions between melanoma and fibroblast cells affect the collective spreading of a heterogeneous population of these cells in vitro. We perform a suite of circular barrier assays that includes: (i) monoculture assays with fibroblast cells; (ii) monoculture assays with SK-MEL-28 melanoma cells; and (iii) a series of co-culture assays initiated with three different ratios of SK-MEL-28 melanoma cells and fibroblast cells. Using immunostaining, detailed cell density histograms are constructed to illustrate how the two subpopulations of cells are spatially arranged within the spreading heterogeneous population. Calibrating the solution of a continuum partial differential equation to the experimental results from the monoculture assays allows us to estimate the cell diffusivity and the cell proliferation rate for the melanoma and the fibroblast cells, separately. Using the parameter estimates from the monoculture assays, we then make a prediction of the spatial spreading in the co-culture assays. Results show that the parameter estimates obtained from the monoculture assays lead to a reasonably accurate prediction of the spatial arrangement of the two subpopulations in the co-culture assays. Overall, the spatial pattern of spreading of the melanoma cells and the fibroblast cells is very similar in monoculture and co-culture conditions. Therefore, we find no clear evidence of any interactions other than cell-to-cell contact and crowding effects.

Highlights

Melanoma is the deadliest form of skin cancer and arises due to the malignant transformation of melanocytes (Geller and Annas, 2003)
Using our estimates of: (i) the melanoma cell diffusivity; (ii) the primary fibroblast cell diffusivity; (iii) the melanoma cell proliferation rate; and, (iv) the primary fibroblast cell proliferation rate, we investigate whether the solution of an appropriate mathematical model describing the coculture experiments, parameterised using data from the monoculture experiments, is able to predict the patterns of spreading in a suite of co-culture experiments where both cell types are present in varying ratios
If we were to observe some interactions, such as melanoma cell migration being stimulated by the presence of fibroblast cells, we can use our mathematical model to explore how these potential interactions might be best observed

Summary

Introduction

Melanoma is the deadliest form of skin cancer and arises due to the malignant transformation of melanocytes (Geller and Annas, 2003). Melanoma spreading takes place in a complex environment that including the extracellular matrix and many different kinds of cell types including: endothelial cells; keratinocytes; fibroblasts and immune cells (Cornil et al, 1991; Flach et al, 2011). Previous experimental work suggests that melanoma cells can interact with fibroblast cells through diffusible factors, such as growth factors and cytokines, or by cell-to-cell contact and crowding (Flach et al, 2011; Goldstein et al, 2005; Labrousse et al, 2004; Ruiter et al, 2002; Zhou et al, 2015). Experimental studies indicate that fibroblasts can play a role in cancer progression, the precise details of how melanoma cells and fibroblast cells interact are not well understood (Kalluri and Zeisberg, 2006; Li et al, 2003)

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