Cancer metastasis is believed to happen through active intravasation but there might be also another way to metastasize. According to passive shedding hypothesis, proposed by Munn et al., tumor cells detach from the tumor mass and passively shed to blood stream through leaky blood vessels. We propose a novel In Vitro Migrational Selection (IVMS) assay that enables the pre-selection of invasive pancreatic cancer Panc-02 cells and create a model of passive shedding. We established invasive sub-cell line of murine pancreatic cancer Panc-02 cells (refered to as Panc02-RS), which exhibited higher metastatic potential in vivo and at the same time decrease in vitro migratory skills, comparing to the initial Panc-02 cell line. In in vitro cell cultures Panc-02 spontaneously detached from the cell culture surface and later reattached and colonized new areas. We believe it can mimic the new way of metastasis, namely passive shedding. We concentrated on Panc-02 model but believe that IVMS might be used to create sub cell lines of many solid tumors to model passive shedding. Our results support the passive shedding hypothesis.

中文翻译：

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一种新型的体外转移模型，支持小鼠胰腺癌Panc-02的被动脱落假说。

癌症转移被认为是通过主动的血管介入而发生的，但也可能存在另一种转移方式。根据Munn等人提出的被动脱落假说，肿瘤细胞从肿瘤块中分离出来，并通过渗漏的血管被动脱落到血流中。我们提出了一种新颖的体外迁移选择（IVMS）检测方法，该方法能够预先选择浸润性胰腺癌Panc-02细胞，并建立被动脱落模型。我们建立了鼠胰腺癌Panc-02细胞（称为Panc02-RS）的侵袭性亚细胞系，与最初的Panc-02细胞相比，其在体内具有更高的转移潜能，同时降低了其迁移能力。线。在体外细胞培养中，Panc-02自发地从细胞培养表面脱离，然后重新附着并定居在新的区域。我们相信它可以模仿新的转移方式，即被动脱落。我们专注于Panc-02模型，但相信IVMS可能会用于创建许多实体瘤的亚细胞系，以模拟被动脱落。我们的结果支持被动脱落假说。