Department of Oral Pathobiological Science and Surgery, Tokyo Dental College, Tokyo, Japan.
Department of Pathology and Oncology, Juntendo University Faculty of Medicine, Tokyo, Japan.
Cancer Med. 2023 Sep;12(17):18062-18077. doi: 10.1002/cam4.6421. Epub 2023 Aug 28.
Cancer-associated fibroblasts (CAFs) are a major stromal component of human breast cancers and often promote tumor proliferation, progression and malignancy. We previously established an experimental CAF (exp-CAF) cell line equipped with a potent tumor-promoting ability. It was generated through prolonged incubation of immortalized human mammary fibroblasts with human breast cancer cells in a tumor xenograft mouse model.
Herein, we found that the exp-CAFs highly express Runt-related transcription factor 3 (RUNX3), while counterpart fibroblasts do not. In breast cancer patients, the proportion of RUNX3-positive stromal fibroblast-like cells tends to be higher in cancerous regions than in non-cancerous regions. These findings suggest an association of RUNX3 with CAF characteristics in human breast cancers. To investigate the functional role of RUNX3 in CAFs, the exp-CAFs with or without shRNA-directed knockdown of RUNX3 were implanted with breast cancer cells subcutaneously in immunodeficient mice. Comparison of the resulting xenograft tumors revealed that tumor growth was significantly attenuated when RUNX3 expression was suppressed in the fibroblasts. Consistently, Ki-67 and CD31 immunohistochemical staining of the tumor sections indicated reduction of cancer cell proliferation and microvessel formation in the tumors formed with the RUNX3-suppressed exp-CAFs.
These results suggest that increased RUNX3 expression could contribute to the tumor-promoting ability of CAFs through mediating cancer cell growth and neoangiogenesis in human breast tumors.
癌症相关成纤维细胞（CAFs）是人类乳腺癌的主要基质成分，通常促进肿瘤增殖、进展和恶性转化。我们之前建立了一个具有强大促肿瘤能力的实验性 CAF（exp-CAF）细胞系。它是通过在肿瘤异种移植小鼠模型中，将永生化的人乳腺成纤维细胞与人类乳腺癌细胞长时间孵育而产生的。
在此，我们发现 exp-CAFs 高度表达 runt 相关转录因子 3（RUNX3），而相应的成纤维细胞则不表达。在乳腺癌患者中，RUNX3 阳性的基质成纤维样细胞在癌组织中的比例倾向于高于非癌组织。这些发现提示 RUNX3 与人类乳腺癌中的 CAF 特征有关。为了研究 RUNX3 在 CAFs 中的功能作用，我们使用 shRNA 靶向敲低 RUNX3 的 exp-CAFs 与乳腺癌细胞一起皮下植入免疫缺陷小鼠。比较产生的异种移植瘤发现，当在成纤维细胞中抑制 RUNX3 表达时，肿瘤生长显著减弱。同样，肿瘤切片的 Ki-67 和 CD31 免疫组织化学染色表明，在具有 RUNX3 抑制的 exp-CAFs 形成的肿瘤中，癌细胞增殖和微血管形成减少。
这些结果表明，RUNX3 表达的增加可能通过介导人类乳腺癌中癌细胞的生长和新生血管形成，促进 CAFs 的促肿瘤能力。
