Tumor-associated macrophage (TAMs) are paramount for tumor progression and immune tolerance in the tumor microenvironment of various types of cancer, including liver cancer. The aim of the present study was to investigate the effect of vascular endothelial growth factor (VEGF) inhibition on TAM polarization and function during their interactions with macrophages and liver cancer cells. TAMs were induced by culturing M0 macrophages with cancer cell-conditioned medium. TAMs cultured with cancer cell-conditioned medium and vascular endothelial growth factor (VEGF) inhibitor were defined as modified TAMs, and the expression levels of TAM-associated markers and VEGF receptor 2 were evaluated using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The effects of TAMs and modified TAMs on cancer cell proliferation and migration were investigated using conditioned medium. Programmed death-ligand 1 (PD-L1) mRNA expression in modified TAMs and cancer cells cultured in modified TAM-conditioned medium (TAM-CM) for 48 h was examined using RT-qPCR. In order to investigate signaling pathways in macrophages, western blot analysis was performed. CD163 and CD206 and M2 macrophage marker expression was upregulated in TAMs and modified TAMs. Modified TAM-CM exhibited a decreased ability to promote cancer cell proliferation and migration in comparison with the use of TAM-CM. The VEGF concentration was significantly higher in the TAMs than in M0 macrophages; however, the modified TAMs displayed a significantly lower VEGF secretion than TAMs. PD-L1 expression was decreased in modified TAMs as compared with TAMs. Western blot analysis revealed that the Akt/mTOR signaling pathway was significantly suppressed in the modified TAMs compared with TAMs. It was observed that TAMs cultured in a VEGF-depleted environment displayed lower secretion levels of cytokines involved in tumor progression and a decreased immune tolerance-inducing ability. On the whole, the results of the present study suggested that VEGF inhibition in TAMs may be a potential therapeutic target for liver cancer.

Irradiation with a specific wavelength of light using light-emitting diodes (LEDs) has various effects on cells and organisms. Recently, the antitumor effects of visible blue light on tumor cells were reported; however, the mechanism and effects on the tumor microenvironment remain unclear. Human colon cancer cells (HCT-116) were injected into the rectal wall of nude mice. Tumors were irradiated with a 465-nm LED light at 30 mW/cm 2 for 30 min. Tumor volumes and the expression levels of opsin 3 (Opn3), autophagy-related factors, cancer-associated fibroblast (CAF) markers, and programmed cell death 1-ligand (PD-L1) were measured. Additionally, human intestinal fibroblasts were cultured in HCT116-conditioned medium (CM) to prepare CAFs. CAFs were divided into an LED group and a control group, and the effect of the LED light on CAF activation in colon cancer cells was examined. Irradiation with blue LED light suppressed tumor growth; Opn3 expression was localized to the cell membrane in the LED group. Irradiated tumors exhibited increased autophagy-related gene expression. Furthermore, in the LED group, TGF-β and α-SMA expression levels in the fibroblasts were decreased. Regarding CAFs, α-SMA and IL-6 expression levels were decreased in the LED group. HCT-116 cells cultured in CAF-CM with LED irradiation showed no enhanced migration or invasion. In the HCT-116 cells cultured in CM of CAFs irradiated with LED, the relative increase in PD-L1 expression was lower than that noted in the CAF-CM without LED irradiation. Blue LED light may have a direct antitumor effect on colon cancer and also an inhibitory effect on CAFs.

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Background The role of the immune system in locally advanced rectal cancer (LARC) following preoperative chemoradiotherapy (CRT) has been widely investigated in recent years. This study examined the prognostic significance of indoleamine-pyrrole 2,3-dioxygenase (IDO) expression in patients with LARC who received preoperative CRT. Methods Ninety patients with LARC who underwent preoperative CRT and curative resection were enrolled. IDO and programmed death-ligand 1 (PD-L1) expression was evaluated by immunohistochemistry. Results Clinicopathological factors did not significantly differ between patients with positive or negative IDO expression, excluding the correlation of positive IDO expression with better tumor differentiation (p = 0.02). IDO expression was not associated with pathological response (p = 0.44), but it was associated with PD-L1 expression. The 5-year overall survival (OS) rate was significantly worse in the IDO-positive group than in the IDO-negative group (64.8% vs. 85.4%, p = 0.02). Univariate analysis identified IDO and PD-L1 expression (p = 0.02), surgical procedure (p = 0.01), final pathological stage (p = 0.003), lymph node metastasis (p < 0.001), and lymphatic invasion (p = 0.002) as significant prognostic factors for OS. Multivariate analysis revealed that IDO expression (HR: 7.10, p = 0.0006), surgical procedure (HR: 5.03, p = 0.01), lymph node metastasis (HR: 2.37, p = 0.04) and lymphatic invasion (HR: 4.97, p = 0.01) were independent prognostic indicators. Disease-free survival was not correlated with IDO or PD-L1 expression. Conclusions IDO expression in patients with LARC who received preoperative CRT could be a potential prognostic indicator. IDO expression could be a useful marker for specifying individual treatment strategies in LARC.