既往研究认为，肿瘤细胞通过狭窄孔隙的极限是约3.0um，而更小的孔隙则不能通过。本课题组设计了一种乳腺癌连续转移模型，鉴定出一系列侵袭性更强的乳腺癌细胞，并利用体外细胞三维培养模型、发现这些细胞能够利用癌周基质通过0.8um的孔隙，远超过了之前认为的肿瘤细胞能通过的下限。我们发现：在转移过程中，乳腺癌细胞须挤压自身才能穿过基底膜中的狭窄孔道，在这种机械压力刺激下，细胞可能通过减少I、III、V型胶原的分泌降低自身硬度，从而有利于细胞用更剧烈的形变来穿过孔隙；另一方面，通过增加IV型胶原合成，使癌周基质增多，形成足够多的孔道和攀附结构，有利于变软的癌细胞持续通过其间向周边侵袭。下一步我们拟通过微流控和活细胞动态观察等技术，探索影响乳腺癌细胞穿过微小孔隙的极限，并分析其关键分子机制。我们的研究有可能提供一个新的理论模型来解释触发和调控肿瘤细胞硬度和穿越狭窄孔隙的分子机制，具有重要的科学价值。

According to previous studies, cancer cells are unable to penetrate tissues through tight interstitial spaces with a diameter smaller than 3.0um. In this study, we established a continuous metastasis model of breast cancer, by which we screened a series of more aggressive and metastatic breast cancer cells. To our surprise, these cells were able to migrate through 0.8um pores with the presence of extracellular matrix (ECM), which is much smaller than the diameter of 3.0um. Our data suggests that during the metastatic process, breast cancer cells must squeeze themselves through the narrow pores in the basement membrane. Under this mechanical stress, the cells may reduce their stiffness by decreasing the secretion of collagen types I, III, and V. Therefore, the softer cells can squeeze themselves to penetrate through the confined tissue spaces. On the other hand, the cell may increase the secretion of type IV collagen to produce more extracellular matrix, which provides sufficient pores and climbing structures for the softer cells to pass through. In the present study, we seek to explore the very limit of the pores size for the breast cancer cells to migrate through by using the microfluidic device and dynamic live cell observation techniques, and clarify the underlying mechanism. Our study may provide a novel model to explain the molecular mechanisms that trigger and regulate the cancer cell stiffness and how they penetrate confined tissue spaces.