Unravel the role of the extracellular N-nicotinamide methyl transferase (eNNMT) in the modulation of radioresistant prostate cancer (PC) tumour immune microenvironment (TIME)

Primary Supervisor: Dr Agata Carreira/Prof. Ian Mills

Project Overview:

Nicotinamide N-methyltransferase (NNMT) is a metabolic enzyme which catalyses the transfer of methyl groups from S-adenosylmethionine to nicotinamide. NNMT levels correlate with increased radioresistance in several solid tumours, including prostate cancer (PC), although the underlying molecular mechanisms remain poorly characterized. We’ve recently described a “moonlighting” function of this enzyme, which can be secreted by cancer cells (extracellular NNMT – eNNMT) and activate TLR4-dependent NF-kB signalling in macrophages. Preliminary data showed that eNNMT is released by PC cells, but how eNNMT may modulate the PC tumour immune microenvironment (TIME) remains unknown. Importantly, PC is largely refractory to immunotherapeutic interventions mainly due to its tumour-immune microenvironment (TIME) with low infiltration of activated anti-tumour immune cells, which highlights the need for therapeutic strategies that can remodel and activate the PC TIME. Thus, this project aims to elucidate the role of eNNMT in shaping the TIME in radioresistant PC. We will take advantage of NNMT-overexpressing radioresistant human and murine immortalized cells to quantify the eNNMT. Radioresistant murine organoids will also be generated. The cellular models will be engineered to knock-down NNMT levels. Multiplexing immunofluorescence will allow the characterization of tumour masses/tumour immune microenvironment collected from xenograft models transplanted with the mentioned models. The effect of extracellular NNMT on immune populations (murine bone marrows (BMs) and spleens; and human PBMCs) also be assessed by flow cytometry. The MSc student will characterize NNMT-overexpressing PC radioresistant cells, quantify the eNNMT release by ELISA, and stablish co-cultures between cancer and immune cells, to gain insight into the signalling pathways primed by eNNMT.

References:

Ghezzi, B., Fiorilla, I., Carreira, Á., Recco, F., Sorci, L., Avalle, L., Ponzano, A., Mazzola, F., Todesco, A.M., Tommasi, N. and Gasparrini, M., 2025. NAMPT and NNMT released via extracellular vesicles and as soluble mediators are distinguished traits of BRAF inhibitor resistance of melanoma cells impacting on the tumor microenvironment. Cell Communication and Signaling, 23(1), p.348.

https://link.springer.com/article/10.1186/s12964-025-02361-2