Mast cells (MCs) are tissue resident sentinels that orchestrate inflammation in response to infection and allergens. They are also frequently observed in tumors, suggesting their contribution in the transition from persistent inflammation to carcinoma. However, the role of MCs in the contest of colorectal cancer (CRC) microenvironment is still debated. In particular, whether different subsets of MCs infiltrate the tumor in different stages of disease progression and whether and how MCs affects tumor development has not been clarified yet.
To gain insight into this issue we will use a conventional model of colitis-induced CRC. We will focus on MC phenotype and functions both in term of granule-stored specific proteases and ability to produce different pro-inflammatory cytokines and pro-angiogenic factors in order to characterize discrete subsets of MCs in tumor microenvironment and their impact on disease progression.
Understanding the role of MCs in tumor development and progression would be of critical importance for the development of new targeted therapies for CRC.
Colorectal cancer (CRC) development and progression are the results of accumulation of genetic alterations as well as the establishment of a pro-tumoral microenvironment.
Due to the complexity of CRC pathogenesis, the identification of novel cellular and molecular players offers the opportunity to discover new biomarkers of prognostic value and/or new targets for therapeutic intervention.
Among different types of immune cells infiltrate CRC, mast cells (MCs) are one of the earliest recruited, suggesting their contribution to tumor progression. However, the role of MCs in tumorigenesis remains controversial: MC-derived mediators can either exert anti-tumorigenic functions, limiting tumor growth, or pro-tumorigenic functions, promoting tumor progression and spread.
Two different subsets of MCs have been identified mainly based on their granule content and their localization. MCs that are predominant in connective tissue and are characterized by granules containing mainly mast cell proteases (MCP) -4, -5 and -6 in mouse and by granules containing both tryptase and chymase in human and MCs localized in mucosal layers that are endowed with MCP-1 and -2 in mouse and tryptase in human. However, due to MC capability to respond to a plethora of different stimuli, MC phenotype and functions may be modulated depending on microenvironment. Little is currently known about the possibility that different MC subsets have different effector functions in terms of cytokine production. Thus, understanding how MC subset distribution and functionality change during CRC progression will allow us to make progress in understanding new mechanisms underlying the pathogenesis of CRC.
We propose to employ a multiparametric flow cytometry approach and RNAscope technology combined to immunofluorescence to identify novel MC subsets with peculiar functional competence and to understand how their functionality is deregulated in the context of inflammation-driven CRC.
Compared to immunohistochemistry, that represent one of the classical approaches in the study of MCs, these technique offer the opportunity to have quantitative data reflecting the whole organ and at the same time define MC activation status in term of cytokine production as well as the spatial relation between inflammatory cells and pathologic tissues.
Globally, our project, by applying traditional and emerging approaches in the study of MC subsets, will dissect their function at various stages of CRC, offering the opportunity to discover novel potential marker of prognostic value and/or new targets for therapeutic intervention.