Crosstalk between cancer and different cancer stroma subtypes promotes the infiltration of tumor-associated macrophages into the tumor microenvironment of oral squamous cell carcinoma

Tumor-associated macrophages (TAMs) are linked to the progression of numerous types of cancer. However, the effects of the tumor microenvironment (TME) of oral squamous cell carcinoma (OSCC), particularly the cancer stroma on TAMs, remains to be elucidated. In the present study, the effects of verrucous SCC-associated stromal cells (VSCC-SCs), SCC-associated stromal cells (SCC-SCs) and human dermal fibroblasts (HDFs) on the differentiation, proliferation and migration of macrophages in vitro was assayed using Giemsa staining, and immunofluorescence, MTS and Transwell (migration) assays, respectively. The combined results suggested that both VSCC-SCs and SCC-SCs promoted the differentiation of macrophages into M2 type TAMs, as well as the proliferation and migration of macrophages following crosstalk with HSC-3 cells in vitro. Moreover, the SCC-SCs exerted a more prominent effect on TAMs than the VSCC-SCs. Immunohistochemical staining was used to examine the expression of CD34, CD45, CD11b and CD163 to assay the effects of VSCC-SCs, SCC-SCs and HDFs on microvessel density (MVD) and the infiltration of CD45(+) monocytes, CD11b(+) TAMs and CD163(+) M2 type macrophages. The results suggested that both VSCC-SCs and SCC-SCs promoted MVD and the infiltration of CD45(+) monocytes, CD11b(+) TAMs and CD163(+) M2 type TAMs into the TME of OSCC following crosstalk with HSC-3 cells in vivo. The SCC-SCs exerted a more prominent promoting effect than the VSCC-SCs. Finally, the potential genes underlying the differential effects of VSCC-SCs and SCC-SCs on the infiltration of TAMs were investigated using microarray analysis. The results revealed that interleukin 1 beta, bone morphogenetic protein 4, interleukin 6 and C-X-C motif chemokine ligand 12 had great potential to mediate the differential effects of VSCC-SCs and SCC-SCs on TAM infiltration. On the whole, the findings presented herein, demonstrate that both VSCC-SCs and SCC-SCs promote the infiltration of TAMs into the TME of OSCC following crosstalk with HSC-3 cells; the SCC-SCs were found to exert a more prominent promoting effect. This may represent a potential regulatory mechanism for the infiltration of TAMs into the TME of OSCC.