  Local cancer invasion of tissue is a complex, multiscale process which plays
an essential role in tumour progression. Occurring over many different temporal
and spatial scales, the first stage of invasion is the secretion of matrix
degrading enzymes (MDEs) by the cancer cells that consequently degrade the
surrounding extracellular matrix (ECM). This process is vital for creating
space in which the cancer cells can progress and it is driven by the activities
of specific matrix metalloproteinases (MMPs). In this paper, we consider the
key role of two MMPs by developing further the novel two-part multiscale model
introduced in [33] to better relate at micro-scale the two micro-scale
activities that were considered there, namely, the micro-dynamics concerning
the continuous rearrangement of the naturally oriented ECM fibres within the
bulk of the tumour and MDEs proteolytic micro-dynamics that take place in an
appropriate cell-scale neighbourhood of the tumour boundary. Focussing
primarily on the activities of the membrane-tethered MT1-MMP and the soluble
MMP-2 with the fibrous ECM phase, in this work we investigate the MT1-MMP/MMP-2
cascade and its overall effect on tumour progression. To that end, we will
propose a new multiscale modelling framework by considering the degradation of
the ECM fibres not only to take place at macro-scale in the bulk of the tumour
but also explicitly in the micro-scale neighbourhood of the tumour interface as
a consequence of the interactions with molecular fluxes of MDEs that exercise
their spatial dynamics at the invasive edge of the tumour.
