Evaluation of pro- and anti-tumor effects induced by three colony-stimulating factors, G-CSF, GM-CSF and M-CSF, in bladder cancer cells: Is G-CSF a friend of bladder cancer cells?

Cytotoxic chemotherapy is the standard treatment for patients with advanced bladder cancer. However, this treatment can cause transient and prolonged neutropenia, which can result in fatal infection. Three recombinant human colony-stimulating factors (CSFs), granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF), and macrophage CSF (M-CSF), are currently available to reduce the duration and degree of neutropenia. The present study investigated the pro- and anti-tumor effects of these three CSFs and the changes in molecular profiles. Xenograft tumors in athymic mice were generated by subcutaneously inoculating the human bladder cancer cell lines MGH-U3 and UM-UC-3. A total of 2 weeks after cell inoculation, mice were randomly divided into four groups (control, G-CSF, GM-CSF and M-CSF) and treated thrice a week for 2 weeks. Tumor growth during monitoring and tumor weight at the time of euthanization were significantly higher in mice treated with G-CSF and lower in mice treated with GM-CSF compared with the control mice. Tumors were examined by immunostaining with antibodies against proteins associated tumor proliferation (Ki-67), angiogenesis [CD31 and vascular endothelial growth factor (VEGF)], anti-immunity (CD204) and epithelial-mesenchymal transition (EMT; E-cadherin). Immunohistochemical staining revealed that tumor proliferation, angiogenesis, recruitment of M2 macrophages and EMT were promoted by G-CSF, whereas lymphangiogenesis and recruitment of M2 macrophages were inhibited by GM-CSF. Treatment-associated changes in serum pro- and anti-tumoral cytokines and chemokines were evaluated by enzyme-linked immunosorbent assay (ELISA)-based arrays. In the ELISA for serum, the levels of cytokines associated with angiogenesis (interleukin-6 and VEGF), and EMT (transforming growth factor-beta 1 and -beta 2) were elevated in mice treated with G-CSF. Treatment with GM-CSF and M-CSF also affected the level of these cytokines characteristically. The current results indicate that administration of exogenous G-CSF to patients with bladder cancer promotes tumor growth through promotion of cell proliferation, angiogenesis, recruitment of M2 macrophages and enhancement of EMT through the modulation of the tumor microenvironment.