Department of Molecular Medicine and Biochemistry, Akita University Graduate School of Medicine, Akita, Japan.
Bioscience Education and Research Support Center, Akita University Graduate School of Medicine, Akita, Japan.
Oncogene. 2017 Aug;36(31):4434-4444. doi: 10.1038/onc.2017.49. Epub 2017 Apr 3.
In the process of cancer spreading, different modes of invasion exist. One is expansive invasion, in which a group of cancer cells gradually expands along with cancer cell proliferation. Invasion of cancer cells is also modified by their interaction with stromal cells including cancer-associated fibroblasts (CAFs). Cancer cells co-invade with CAFs, and invasion by CAFs frequently precede invasion by cancer cells, which indicates CAF-led cancer cell invasion. Here, we show that CAFs induce apoptosis in gastric cancer cells, which prevented expansive invasion by cancer cells and instead facilitated CAF-led invasion. Death receptor 4 and activation of caspase-8 in cancer cells mediated cancer cell apoptosis induced by CAFs, which was dependent on contact between cancer cells and CAFs. Apoptotic cancer cells in turn released apoptotic vesicles and stimulated invasion of CAFs. Accordingly, cancer cells followed the migrating CAFs. Treatment with a caspase inhibitor, ZVAD, or forced expression of a death domain fragment in cancer cells prevented cancer cell apoptosis induced by CAFs and increased expansive invasion by cancer cells in extracellular gel invasion assays, while the rate of cancer cell invasion led by CAFs was decreased. Death domain-fragment expression also prevented intramural invasion by gastric cancer cells in the stomach. Because CAF-led invasion is characterized by the movement of individual cancer cells away from the tumour, adequate cancer cell apoptosis may promote cancer dissemination.
在癌症扩散的过程中,存在不同的侵袭模式。一种是扩张性侵袭,一群癌细胞随着癌细胞的增殖而逐渐扩散。癌细胞的侵袭也受到其与间质细胞(包括癌相关成纤维细胞(CAFs))相互作用的影响。癌细胞与 CAFs 共同侵袭,并且 CAFs 的侵袭往往先于癌细胞的侵袭,这表明 CAF 主导的癌细胞侵袭。在这里,我们表明 CAFs 诱导胃癌细胞凋亡,这阻止了癌细胞的扩张性侵袭,反而促进了 CAF 主导的侵袭。CAFs 诱导的癌细胞凋亡依赖于癌细胞与 CAFs 之间的接触,通过死亡受体 4 和半胱天冬酶-8 的激活在癌细胞中起作用。凋亡的癌细胞反过来释放凋亡小体并刺激 CAFs 的侵袭。因此,癌细胞跟随迁移的 CAFs。用半胱天冬酶抑制剂 ZVAD 处理或在癌细胞中强制表达死亡域片段,可防止 CAFs 诱导的癌细胞凋亡,并增加细胞外凝胶侵袭试验中癌细胞的扩张性侵袭,而 CAFs 主导的癌细胞侵袭率则降低。死亡域片段的表达也阻止了胃癌细胞在胃中的壁内侵袭。因为 CAF 主导的侵袭的特点是单个癌细胞远离肿瘤的运动,所以足够的癌细胞凋亡可能会促进癌症的扩散。