CXCR4 Expression and Cancer-associated Fibroblasts May Play an Important Role in the Invasion of Low-grade Endometrioid Carcinoma

Well-differentiated endometrioid carcinoma (EC) is a low-grade cancer with relatively indolent behavior. However, even with well-differentiated histology, it sometimes tends to invade extensively and shows metastatic potential, suggesting that this is a group of cancers with heterogeneous behavior. In contrast, due to its tendency for younger onset, the treatment strategy for EC frequently considers fertility preservation, highlighting the need for a more accurate evaluation of myometrial invasion through biopsy and imaging diagnostics. We previously reported the involvement of the CXCR4–CXCL12 and CXCL14 axes in EC invasion. Accordingly, we investigated whether CXCR4 expression could reflect invasive potential and explored its interaction with cancer-associated fibroblasts that produce chemokines in the tumor microenvironment. Immunohistochemical expression of CXCR4 was assessed in 71 cases of EC (14 of EC confined to the endometrium and 57 of myoinvasive EC), 6 cases of endometrial intraepithelial neoplasia, and 42 cases of noncarcinomatous conditions. CXCR4 expression was significantly higher in myoinvasive EC than in noncancerous conditions, endometrial intraepithelial neoplasia, and endometrium-confined EC. By univariate and multivariate analysis, CXCR4 expression significantly reflected myometrial invasion. CXCR4 expression in the biopsied and resected specimens correlated weakly positively. Invasion and wound-healing assays were performed culturing an EC cell line in a cancer-associated fibroblast-conditioned medium. The invasion and wound-healing potentials were dependent on CXCR4 and cancer-associated fibroblast. Our study demonstrated that CXCR4 expression is an independent factor in myometrial invasion and can support diagnostic evaluation before treatment in the biopsy sample.