NF-κB: Governing Macrophages in Cancer

Tumor-associated macrophages (TAMs) are the major component of the tumor microenvironment (TME), where they sustain tumor progression and or-tumor immunity. Due to their plasticity, macrophages can exhibit anti- or pro-tumor functions through the expression of different gene sets leading to distinct macrophage phenotypes: M1-like or pro-inflammatory and M2-like or anti-inflammatory. NF-κB transcription factors are central regulators of TAMs in cancers, where they often drive macrophage polarization toward an M2-like phenotype. Therefore, the NF-κB pathway is an attractive therapeutic target for cancer immunotherapy in a wide range of human tumors. Hence, targeting NF-κB pathway in the myeloid compartment is a potential clinical strategy to overcome microenvironment-induced immunosuppression and increase anti-tumor immunity. In this review, we discuss the role of NF-κB as a key driver of macrophage functions in tumors as well as the principal strategies to overcome tumor immunosuppression by targeting the NF-κB pathway.

The NF-κB Pharmacopeia: Novel Strategies to Subdue an Intractable Target

NF-κB transcription factors are major drivers of tumor initiation and progression. NF-κB signaling is constitutively activated by genetic alterations or environmental signals in many human cancers, where it contributes to almost all hallmarks of malignancy, including sustained proliferation, cell death resistance, tumor-promoting inflammation, metabolic reprogramming, tissue invasion, angiogenesis, and metastasis. As such, the NF-κB pathway is an attractive therapeutic target in a broad range of human cancers, as well as in numerous non-malignant diseases. Currently, however, there is no clinically useful NF-κB inhibitor to treat oncological patients, owing to the preclusive, on-target toxicities of systemic NF-κB blockade. In this review, we discuss the principal and most promising strategies being developed to circumvent the inherent limitations of conventional IκB kinase (IKK)/NF-κB-targeting drugs, focusing on new molecules that target upstream regulators or downstream effectors of oncogenic NF-κB signaling, as well as agents targeting individual NF-κB subunits.

NF-κB: blending metabolism, immunity, and inflammation

The procurement and management of nutrients and ability to fight infections are fundamental requirements for survival. These defense responses are bioenergetically costly, requiring the immune system to balance protection against pathogens with the need to maintain metabolic homeostasis. NF-κB transcription factors are central regulators of immunity and inflammation. Over the last two decades, these factors have emerged as a pivotal node coordinating the immune and metabolic systems in physiology and the etiopathogenesis of major threats to human health, including cancer, autoimmunity, chronic inflammation, and others. In this review, we discuss recent advances in understanding how NF-κB-dependent metabolic programs control inflammation, metabolism, and immunity and how improved knowledge of them may lead to better diagnostics and therapeutics for widespread human diseases.

New Insights into Cancer Targeted Therapy: Nodal and Cripto-1 as Attractive Candidates

The transforming growth factor beta (TGF-β) signaling is fundamental for correct embryonic development. However, alterations of this pathway have been correlated with oncogenesis, tumor progression and sustaining of cancer stem cells (CSCs). Cripto-1 (CR-1) and Nodal are two embryonic proteins involved in TGF-β signaling. Their expression is almost undetectable in terminally differentiated cells, but they are often re-expressed in tumor cells, especially in CSCs. Moreover, cancer cells that show high levels of CR-1 and/or Nodal display more aggressive phenotypes in vitro, while in vivo their expression correlates with a worse prognosis in several human cancers. The ability to target CSCs still represents an unmet medical need for the complete eradication of certain types of tumors. Given the prognostic role and the selective expression of CR-1 and Nodal on cancer cells, they represent archetypes for targeted therapy. The aim of this review is to clarify the role of CR-1 and Nodal in cancer stem populations and to summarize the current therapeutic strategy to target CSCs using monoclonal antibodies (mAbs) or other molecular tools to interfere with these two proteins.