Bevacizumab exerts anti-angiogenic effects in cancer patients by inhibiting vascular endothelial growth factor (VEGF). However, its use is still limited due to the development of resistance to the treatment. Such resistance can be regulated by various factors, although the underlying mechanisms remain incompletely understood. Here we show that bone marrow-derived fibrocyte-like cells, defined as alpha-1 type I collagen-positive and CXCR4-positive cells, contribute to the acquired resistance to bevacizumab. In mouse models of malignant pleural mesothelioma and lung cancer, fibrocyte-like cells mediate the resistance to bevacizumab as the main producer of fibroblast growth factor 2. In clinical specimens of lung cancer, the number of fibrocyte-like cells is significantly increased in bevacizumab-treated tumours, and correlates with the number of treatment cycles, as well as CD31-positive vessels. Our results identify fibrocyte-like cells as a promising cell biomarker and a potential therapeutic target to overcome resistance to anti-VEGF therapy.

Surfactant protein A (SP-A) is a large multimeric protein found in the lungs. In addition to its immunoregulatory function in infectious respiratory diseases, SP-A is also used as a marker of lung adenocarcinoma. Despite the finding that SP-A expression levels in cancer cells has a relationship with patient prognosis, the function of SP-A in lung cancer progression is unknown. We investigated the role of SP-A in lung cancer progression by introducing the SP-A gene into human lung adenocarcinoma cell lines. SP-A gene transduction suppressed the progression of tumor in subcutaneous xenograft or lung metastasis mouse models. Immunohistochemical analysis showed that the number of M1 antitumor tumor-associated macrophages (TAMs) was increased and the number of M2 tumor-promoting TAMs was not changed in the tumor tissue produced by SP-Aeexpressing cells. In addition, natural killer (NK) cells were also increased and activated in the SP-Aeexpressing tumor. Moreover, SP-A did not inhibit tumor progression in mice depleted of NK cells. Taking into account that SP-A did not directly activate NK cells, these results suggest that SP-A inhibited lung cancer progression by recruiting and activating NK cells via controlling the polarization of TAMs. (Am J Pathol 2013 http:// dx

Antibodies against immune checkpoint inhibitors such as anti-programmed cell death protein 1 (PD-1) and anti-programmed death ligand 1 (PD-L1) play a key role in the treatment of advanced lung cancer. To examine the clinical benefits of these agents, preclinical and clinical studies have been conducted to identify definitive biomarkers associated with cancer status. Analysis of the blood and feces of tumor patients has attracted attention in recent studies attempting to identify non-invasive biomarkers such as cytokines, soluble PD-L1, peripheral blood mononuclear cells, and gut microbiota. These factors are believed to interact with each other to produce synergistic effects and contribute to the formation of the tumor immune microenvironment through the seven steps of the cancer immunity cycle. The immunogram was first introduced as a novel indicator to define the immunity status of cancer patients. In this review, we discuss the progress in the identification of predictive biomarkers as well as future prospects for anti-PD-1/PD-L1 therapy.

Thymidine phosphorylase (TP), a rate-limiting enzyme in thymidine catabolism, plays a pivotal role in tumor progression; however, the mechanisms underlying this role are not fully understood. Here, we found that TP-mediated thymidine catabolism could supply the carbon source in the glycolytic pathway and thus contribute to cell survival under conditions of nutrient deprivation. In TP-expressing cells, thymidine was converted to metabolites, including glucose 6-phosphate, lactate, 5-phospho-α-D-ribose 1-diphosphate, and serine, via the glycolytic pathway both in vitro and in vivo. These thymidine-derived metabolites were required for the survival of cells under low-glucose conditions. Furthermore, activation of thymidine catabolism was observed in human gastric cancer. These findings demonstrate that thymidine can serve as a glycolytic pathway substrate in human cancer cells.

Notch signaling regulates cell-fate decisions during development and postnatal life. Little is known, however, about the role of Delta-like-4 (Dll4)-Notch signaling between cancer cells, or how this signaling affects cancer metastasis. We, therefore, assessed the role of Dll4-Notch signaling in cancer metastasis. We generated a soluble Dll4 fused to the IgG1 constant region (Dll4-Fc) that acts as a blocker of Dll4-Notch signaling and introduced it into human small cell lung cancer (SCLC) cell lines expressing either high levels (SBC-3 and H1048) or low levels (SBC-5) of Dll4. The effects of Dll4-Fc on metastasis of SCLC were evaluated using a mouse model. Although Dll4-Fc had no effect on the liver metastasis of SBC-5, the number of liver metastasis inoculated with SBC-3 and H1048 cells expressing Dll4-Fc was significantly lower than that injected with control cells. To study the molecular mechanisms of the effects of Dll4-Fc on liver metastasis, a PCR array analysis was conducted. Because the expression of NF-kB target genes was affected by Dll4-Fc, we conducted an electrophoretic mobility shift assay and observed that NF-kB activities, both with and without stimulation by TNF-a, were downregulated in Dll4-Fc-overexpressing SBC-3 and H1048 cells compared with control cells. Moreover, Dll4-Fc attenuates, at least in part, the classical and alternative NF-kB activation pathway by reducing Notch1 signaling. These results suggest that Dll4-Notch signaling in cancer cells plays a critical role in liver metastasis of SCLC by regulating NF-kB signaling.