SPP1 + macrophages in colorectal cancer: Markers of malignancy and promising therapeutic targets

The Landscape of SPP1+ Macrophages Across Tissues and Diseases: A Comprehensive Review

Macrophages play a critical role in shaping the immune landscape of various diseases, with secreted phosphoprotein 1 (SPP1)-expressing macrophages emerging as a distinct subset implicated in both cancerous and non-cancerous conditions. Leveraging recent advances in single-cell RNA sequencing, numerous studies have identified SPP1+ macrophages across diverse pathological contexts, shedding light on their functional heterogeneity. In cancer, SPP1+ tumour-associated macrophages contribute to tumour growth, angiogenesis, and immune evasion, often interacting with T cells and stromal components to sustain an immunosuppressive microenvironment. Conversely, in non-cancerous diseases, these macrophages exhibit both profibrotic and disease-promoting properties, depending on the tissue context. This review provides a comprehensive synthesis of the latest findings on SPP1+ macrophages, highlighting their roles in tumour progression, immune suppression, tissue remodelling, and fibrosis. By comparing their shared traits and tissue-specific differences, we explore how SPP1+ macrophages adapt to distinct microenvironments and influence disease progression. Understanding their conserved and context-dependent functions may open new avenues for therapeutic targeting.

Targeting of TAMs: can we be more clever than cancer cells?

АBSTRACT: With increasing incidence and geography, cancer is one of the leading causes of death, reduced quality of life and disability worldwide. Principal progress in the development of new anticancer therapies, in improving the efficiency of immunotherapeutic tools, and in the personification of conventional therapies needs to consider cancer-specific and patient-specific programming of innate immunity. Intratumoral TAMs and their precursors, resident macrophages and monocytes, are principal regulators of tumor progression and therapy resistance. Our review summarizes the accumulated evidence for the subpopulations of TAMs and their increasing number of biomarkers, indicating their predictive value for the clinical parameters of carcinogenesis and therapy resistance, with a focus on solid cancers of non-infectious etiology. We present the state-of-the-art knowledge about the tumor-supporting functions of TAMs at all stages of tumor progression and highlight biomarkers, recently identified by single-cell and spatial analytical methods, that discriminate between tumor-promoting and tumor-inhibiting TAMs, where both subtypes express a combination of prototype M1 and M2 genes. Our review focuses on novel mechanisms involved in the crosstalk among epigenetic, signaling, transcriptional and metabolic pathways in TAMs. Particular attention has been given to the recently identified link between cancer cell metabolism and the epigenetic programming of TAMs by histone lactylation, which can be responsible for the unlimited protumoral programming of TAMs. Finally, we explain how TAMs interfere with currently used anticancer therapeutics and summarize the most advanced data from clinical trials, which we divide into four categories: inhibition of TAM survival and differentiation, inhibition of monocyte/TAM recruitment into tumors, functional reprogramming of TAMs, and genetic enhancement of macrophages.