Role of extracellular matrix malleability in mediating breast cancer cell invasion and migration

乳腺导管癌是乳腺癌中最常见的一种，可发展为浸润性导管癌 (IDC)当癌通过基底膜（BM）侵入基质组织时。入侵是一个 导管癌进展的一个关键步骤，与转移的可能性增加有关， 乳腺癌最致命的一面在转移过程中，癌细胞也必须在浸润过程中侵入BM 和外渗。认为癌细胞在侵袭BM期间利用蛋白酶降解BM 使用被称为侵入伪足的特殊结构。已知的蛋白酶非依赖性入侵模式， 涉及细胞通过ECM中的孔挤压的迁移将被 BM。然而，生理ECM是粘弹性的，表现出粘性流体的一些特性，并且 细胞力可引起基质的流动和永久变形。换句话说，粘弹性ECM是 延展性，细胞产生的力可以扩大孔隙，为细胞提供机械地 重塑ECM并物理清除迁移路径，不依赖于蛋白酶。虽然韧性是 它与基质粘度有关，不同于基质弹性。有趣的是，恶性乳腺病变已经 发现比良性病变表现出更大程度的粘性。重要的是，延展性的概念可能 也与蛋白酶依赖性迁移有关，因为蛋白酶的作用可能是使基质 更具可塑性在本申请中要测试的具体假设是，延展性是一个关键的物理特性， 介导蛋白酶依赖性和蛋白酶非依赖性癌细胞侵袭的BM参数， 迁移这一假设得到了初步研究的支持，初步研究发现癌细胞可以侵入和迁移， 通过含有在蛋白酶中具有中等或高延展性的BM配体的纳米多孔基质- 独立的方式，利用侵入足样突起来启动侵入，但不能侵入， 通过低延展性的基质迁移。这一假设将通过以下三个方面进行检验 具体目标：（1）制造具有独立可调延展性的3D细胞培养材料， 与乳腺上皮BM相关的配体和刚度;（2）确定ECM延展性如何调节 内陷足突;（3）！确定蛋白酶的分子和生物物理机制- 通过具有不同延展性水平的ECM独立迁移。这种方法是创新的，因为 它的重点是了解可塑性在介导蛋白酶独立和依赖的作用， 侵入和迁移，因为延展性是ECM的物理特性，与基质粘度有关， 与弹性或密度不同，弹性或密度在迄今为止的研究中基本上被忽视。拟议的研究是 重要的是，它将揭示ECM延展性在介导蛋白酶依赖性和 乳腺癌细胞的蛋白酶非依赖性侵袭和迁移，可能揭示了以前未发现的 描述了入侵或迁移的方式。

Ductal carcinoma is the most common form of breast cancer and progresses to Invasive Ductal Carcinoma (IDC) when the carcinoma invades through the basement membrane (BM) into the stromal tissue. Invasion is a key step in ductal carcinoma progression that is associated with an increased likelihood for metastasis, the most deadly aspect of breast cancer. During metastasis, cancer cells must also invade BM during intravasation and extravasation. Cancer cells are thought to utilize proteases to degrade the BM during invasion of the BM using specialized structures known as invadopodia. Known modes of protease-independent invasion and migration, involving cells squeezing through pores in the ECM, would be inhibited by the nanoporous nature of the BM. However, physiological ECM is viscoelastic, exhibiting some characteristics of viscous fluids, and cellular forces can induce flow and permanent deformation of the matrix. In other words, viscoelastic ECM is malleable, and cell generated forces may expand pores, providing a mechanism for cells to mechanically remodel the ECM and physically clear a path for migration, independent of proteases. While malleability is related to matrix viscosity, it is distinct from matrix elasticity. Interestingly, malignant breast lesions have been found to exhibit a greater degree of viscosity than benign lesions. Importantly, the concept of malleability might be relevant to protease-dependent migration as well, as the action of proteases may be to make the matrix more malleable. The specific hypothesis to be tested in this application is that malleability is a key physical parameter of the BM that mediates protease-dependent and protease-independent cancer cell invasion and migration. This hypothesis is supported by preliminary studies finding that cancer cells can invade and migrate through nanoporous matrices that contain BM ligands with intermediate or high-malleability in a protease- independent manner, utilizing invadopodial like protrusions to initiate invasion, but are unable to invade and migrate through matrices with low malleability. This hypothesis will be tested by pursuing the following three specific aims: (1) Fabricate materials for 3D cell culture with independently tunable malleability that present ligands and stiffness relevant to the BM of mammary epithelium; (2) Determine how ECM malleability regulates invadopodial protrusions; and (3)! Identify molecular and biophysical mechanisms underlying protease- independent migration through ECMs with different levels of malleability. This approach is innovative because of its focus on understanding the role of malleability in mediating protease-independent and -dependent invasion and migration, as malleability is a physical characteristic of ECM, related to matrix viscosity but distinct from elasticity or density, which has been largely ignored in studies to date. The proposed research is significant because it will reveal the role of ECM malleability in mediating both protease-dependent and protease-independent invasion and migration by breast cancer cells, potentially uncovering previously un- described modes of invasion or migration.