Embryonic Origin and Subclonal Evolution of Tumor-Associated Macrophages Imply Preventive Care for Cancer.

Macrophages are widely distributed in tissues and function in homeostasis. During cancer development, tumor-associated macrophages (TAMs) dominatingly support disease progression and resistance to therapy by promoting tumor proliferation, angiogenesis, metastasis, and immunosuppression, thereby making TAMs a target for tumor immunotherapy. Here, we started with evidence that TAMs are highly plastic and heterogeneous in phenotype and function in response to microenvironmental cues. We pointed out that efforts to tear off the heterogeneous "camouflage" in TAMs conduce to target de facto protumoral TAMs efficiently. In particular, several fate-mapping models suggest that most tissue-resident macrophages (TRMs) are generated from embryonic progenitors, and new paradigms uncover the ontogeny of TAMs. First, TAMs from embryonic modeling of TRMs and circulating monocytes have distinct transcriptional profiling and function, suggesting that the ontogeny of TAMs is responsible for the functional heterogeneity of TAMs, in addition to microenvironmental cues. Second, metabolic remodeling helps determine the mechanism of phenotypic and functional characteristics in TAMs, including metabolic bias from macrophages' ontogeny in macrophages' functional plasticity under physiological and pathological conditions. Both models aim at dissecting the ontogeny-related metabolic regulation in the phenotypic and functional heterogeneity in TAMs. We argue that gleaning from the single-cell transcriptomics on subclonal TAMs' origins may help understand the classification of TAMs' population in subclonal evolution and their distinct roles in tumor development. We envision that TAM-subclone-specific metabolic reprogramming may round-up with future cancer therapies.

[Synergistic effect of targeted inhibition of MEK/ERK and PI3K/AKT survival signaling pathways on induction of apoptosis in melanoma].

OBJECTIVE: The treatment of metastatic melanoma by conventional chemotherapeutic agents remains unsatisfactory. The present study was undertaken to reveal the role of co-inhibition of survival signaling pathways in apoptosis of melanoma cells. METHODS: A panel of human melanoma cell lines and fresh melanoma isolates was assessed for their sensitivity to the MEK inhibitor U0126 and/or AKT inhibitor LY294002. The proliferation and apoptosis of the cells were examined after treatment with the inhibitors. RESULTS: Constitutive activation of ERK1/2 and AKT was closely related to concentrations of serum in the culture medium (extracellular signals). The sensitivity of melanoma cells to apoptosis induced by inhibition of MEK/ERK was not correlated with the active BRAF mutation (BRAF(V600E)). Inhibition of MEK/ERK predominantly induced apoptosis; whereas inhibition of PI3K/AKT primarily inhibited proliferation. Co-inhibition of MEK/ERK1/2 and PI3K/AKT synergistically induced apoptosis. CONCLUSION: Co-targeting MEK/ERK and PI3K/AKT pathways may further improve treatment for melanoma.