Multicellular spheroid-based tumor cell model as a preclinical tool to study therapy-induced senescence

A better understanding of the complex metabolic reprogramming induced by radio- and chemotherapy is essential to define the pathways involved in treatment resistance and senescence development, which contribute to cancer development. New insights on the metabolic reprogramming linked to senescence may derive from Matrix-assisted Laser Desorption/Ionization-Mass Spectrometry (MALDI-MSI), a label-free technique that enables the characterization of the spatial distribution of multiple endogenous species in tissue and artificial spheroids.
MCF7 cells-originated spheroids have been developed to be used as a model to study the effects of radio- and chemotherapy. In fact, 3D multicellular tumor spheroids can better simulate the spatial structure, hypoxia and nutrient gradient, extracellular matrix (ECM) deposition and drug resistance mechanisms of tumors in vivo. Such model can be applied for high-throughput therapy-induced senescence screening and evaluation, relevant for cancer progression, and can also be utilized to initiate a series of fundamental research programs regarding cell and drug targeting and immune mechanisms.

Here, we show the acquisition of images related to outer and inner characterizing lipids in MCF7 spheroids with IMS. Representatively, MCF7 spheroids display a concentric, layered structure consisting of a necrotic core, a resting cells layer and an outer border of proliferating cells. Here we highlight a signal at m/z 909 (by negative ion mode), which is specifically linked to the proliferative regions (Fig. A), and another signal at m/z 863, enriched in the necrotic core in MCF7 spheroids (Fig. B).
The challenge now is recognize senescent cells within the spheroids and to define a panel of m/z signals that derive unequivocally from senescent cells only. This would enable the detection of senescent cells in a complex structure such as the tumor microenvironment in a label-free and relatively quick way, which in turn would allow the targeting and eventual elimination of these cells.