In this section, we will primarily discuss the studies aiming to re-polarize

TAMs to M1-type. The agents used and the proteins targeted will be outlined. Those studies for hampering the functions of M2-like TAMs will be discussed in the next section. The NF-κB pathway can positively modulate the transcription of PD0325901 mw Th1-response cytokines in most circumstances. It is known that the attenuated NF-κB activation in TAMs mediates their immunosuppressive M2 property; whereas NF-κB reactivation can redirect TAMs to a tumoricidal M1-like phenotype.[76] By now, several agents with definite roles in activating NF-κB have been reported. They include the agonists of Toll-like receptors (TLRs), anti-CD40 mAb and anti-IL-10R mAb. The TLR agonists are diverse, CHIR 99021 including PolyI:C (for

TLR3), lipopolysaccharide (LPS) and monophosphoryl A (for TLR4), imiquimod and R-848 (for TLR7), and CpG-oligodeoxynucleotide (CpG-ODN, for TLR9). First, PolyI:C is a dsRNA analogy that can reverse tumour-supporting macrophages to tumour-suppressing macrophages via TLR3.[77, 78] Second, LPS is a well-known activator of the NF-κB pathway and is important in the establishment of the M1 phenotype of macrophages. The detoxified derivative of LPS, monophosphoryl lipid A, has also shown promise as an adjuvant of anti-cancer vaccines.[79] Clinical trials of this drug are ongoing. Third, as a ligand for TLR7/8, imiquimod attracts a certain amount of attention, because it could promote the Th1 cytokine production in antigen-presenting cells and enhance the anti-tumour responses of lymphocytes.[80, 81] In a topical therapy for cutaneous squamous cell carcinoma, imiquimod polarized monocytes/macrophages to an M1 pattern.[82] Another agent similar to imiquimod is R-848.[83] Importantly, TLR7/8 agonists can enhance the destruction of antibody-coated tumour cells by macrophages.[83] Finally, CpG-ODN draws considerable attention because it has been widely used as an adjuvant of tumour-specific antigen vaccines, mechanically standing on the basis that the activation

of TLR9 can up-regulate the trans-activity GNE-0877 of NF-κB in macrophages.[84] Synthetic CpG-ODN is a powerful compound in promoting macrophages to produce IL-12, IFN-α/β and TNF-α.[85, 86] Moreover, it has been reported that the combined treatment of CpG-ODN with other agents, such as CCL-16 and anti-IL-10R mAb, rapidly switched infiltrating macrophages from M2 type to M1 type, and triggered innate responses debulking large tumours within 16 hr.[87] Currently, CpG-ODN-based therapies are in clinical trials for the treatment of various cancers.[88-93] The antibodies against the membrane receptors on the up-stream part of the NF-κB pathway are also inspiring for TAM modulation. One such antibody is anti-CD40 mAb.