林 孝典

Adipocyte-cancer cell interactions promote tumor development and progression. Previously, we identified adipsin (CFD) and its downstream effector, hepatocyte growth factor (HGF), as adipokines that enhance adipocyte-breast cancer stem cell interactions. Here, we show that adipsin-dependent adipocyte maturation and the subsequent upregulation of HGF promote tumor invasion in breast cancers. Mature adipocytes, but not their precursors, significantly induced breast tumor cell migration and invasion in an adipsin expression-dependent manner. Promoters of tumor invasion, galectin 7 and matrix metalloproteinases, were significantly upregulated in cancer cells cocultured with mature adipocytes; meanwhile, their expression levels in cancer cells cocultured with adipocytes were reduced by adipsin knockout (Cfd KO) or a competitive inhibitor of CFD. Tumor growth and distant metastasis of mammary cancer cells were significantly suppressed when syngeneic mammary cancer cells were transplanted into Cfd KO mice. Histological analyses revealed reductions in capsular formation and tumor invasion at the cancer-adipocyte interface in the mammary tumors formed in Cfd KO mice. These findings indicate that adipsin-dependent adipocyte maturation may play an important role in adipocyte-cancer cell interaction and breast cancer progression.

Epithelial-mesenchymal transition (EMT) plays a pivotal role in cancer metastasis and treatment resistance, which worsens prognosis. In phase III trials, eribulin improved overall survival in metastatic breast cancer (MBC) patients. In preclinical studies, eribulin suppressed EMT. However, clinical data on the use of eribulin for MBC patients are limited. In this exploratory, prospective study, we examined the effect of eribulin on EMT in MBC patients. Twenty-two patients aged 44-82 years with recurrent breast cancer or MBC were treated with eribulin. Breast cancer tissue samples were obtained before treatment and on day 15 ± 5 of the first cycle of eribulin treatment. EMT markers (E-cadherin, claudin-3, vimentin, N-cadherin) were analysed using western blotting. EMT changes were evaluated based on the ratio of epithelial to mesenchymal markers before and after treatment in individual tumours. E-cadherin/vimentin, claudin-3/vimentin, E-cadherin/N-cadherin, and claudin-3/N-cadherin ratios were significantly higher after treatment (P = 0.007, P = 0.005, P = 0.006, and P = 0.011, respectively). Based on E-cadherin/vimentin, 65.0% of tumours shifted to an epithelial phenotype, as compared to 66.7% based on claudin-3/vimentin, 84.6% based on E-cadherin/N-cadherin, and 71.4% based on claudin-3/N-cadherin ratios. Thus, our results showed that eribulin suppressed EMT in breast cancer tissues.

BACKGROUND: MicroRNAs (miRNAs) are key regulators of stem cell functions, including self-renewal and differentiation. In this study, we aimed to identify miRNAs that are upregulated during terminal differentiation in the human colon epithelium, and elucidate their role in the mechanistic control of stem cell properties. METHODS: "Bottom-of-the-crypt" (EPCAM+/CD44+/CD66alow) and "top-of-the-crypt" (EPCAM+/CD44neg/CD66ahigh) epithelial cells from 8 primary colon specimens (6 human, 2 murine) were purified by flow cytometry and analyzed for differential expression of 335 miRNAs. The miRNAs displaying the highest upregulation in "top-of-the-crypt" (terminally differentiated) epithelial cells were tested for positive correlation and association with survival outcomes in a colon cancer RNA-seq database (n = 439 patients). The two miRNAs with the strongest "top-of-the-crypt" expression profile were evaluated for capacity to downregulate self-renewal effectors and inhibit in vitro proliferation of colon cancer cells, in vitro organoid formation by normal colon epithelial cells and in vivo tumorigenicity by patient-derived xenografts (PDX). RESULTS: Six miRNAs (miR-200a, miR-200b, miR-200c, miR-203, miR-210, miR-345) were upregulated in "top-of-the-crypt" cells and positively correlated in expression among colon carcinomas. Overexpression of the three miRNAs with the highest inter-correlation coefficients (miR-200a, miR-200b, miR-200c) associated with improved survival. The top two over-expressed miRNAs (miR-200c, miR-203) cooperated synergistically in suppressing expression of BMI1, a key regulator of self-renewal in stem cell populations, and in inhibiting proliferation, organoid-formation and tumorigenicity of colon epithelial cells. CONCLUSION: In the colon epithelium, terminal differentiation associates with the coordinated upregulation of miR-200c and miR-203, which cooperate to suppress BMI1 and disable the expansion capacity of epithelial cells.

Adipose tissue is a component of the tumor microenvironment and is involved in tumor progression. We have previously shown that adipokine adipsin (CFD) functions as an enhancer of tumor proliferation and cancer stem cell (CSC) properties in breast cancers. We established the Cfd-knockout (KO) mice and the mammary adipose tissue-derived stem cells (mADSCs) from them. Cfd-KO in mADSCs significantly reduced their ability to enhance tumorsphere formation of breast cancer patient-derived xenograft (PDX) cells, which was restored by the addition of Cfd in the culture medium. Hepatocyte growth factor (HGF) was expressed and secreted from mADSCs in a Cfd-dependent manner. HGF rescued the reduced ability of Cfd-KO mADSCs to promote tumorsphere formation in vitro and tumor formation in vivo by breast cancer PDX cells. These results suggest that HGF is a downstream effector of Cfd in mADSCs that enhances the CSC properties in breast cancers.