Tumour-intrinsic alterations and stromal matrix remodelling promote Wnt-niche independence during diffuse-type gastric cancer progression
Menée notamment à partir de l'analyse transcriptomique spatiale d'échantillons tumoraux à différents stades d'un cancer gastrique héréditaire de type diffus et menée à l'aide d'un modèle d'organoïde, cette étude met en évidence un mécanisme par lequel la modification de la matrice extracellulaire et l'expression, par les cellules cancéreuses, de ligands de protéines Wnt favorisent la voie de signalisation Wnt durant la progression tumorale et permettent l'expansion des cellules cancéreuses indifférenciées nécessaires au développement de tumeurs hautement prolifératives et métastatiques
Background : Development of diffuse-type gastric cancer (DGC) starts with intramucosal lesions that are primarily composed of differentiated, non-proliferative signet ring cells (SRCs). These indolent lesions can advance into highly proliferative and metastatic tumours, which requires suppression of DGC cell differentiation.
Objective : Our goal was to identify molecular changes contributing to the progression of indolent to aggressive DGC lesions.
Design : We conducted spatial transcriptomic analysis of patient tumours at different stages of hereditary DGC, comparing transcriptional differences in tumour cell populations and tumour-associated cells. We performed functional analysis of identified changes in a human gastric (CDH1KO) organoid model recapitulating DGC initiation.
Results : Our analysis reveals that distinct DGC cell populations exhibit varying levels of Wnt-signalling activity, and high levels of Wnt signalling prevent differentiation into SRCs. We identify multiple adaptations during DGC progression that converge on Wnt signalling, allowing tumour cells to remain in an undifferentiated state as they disseminate away from the gastric stem cell niche. First, DGC cells establish a cell-autonomous source for Wnt-pathway activation through upregulated expression of Wnt-ligands and ‘secreted frizzled-related protein 2’ (SFRP2) that potentiates ligand-induced Wnt signalling. Second, early tumour development is marked by extracellular matrix remodelling, including increased deposition of collagen I whose interactions with DGC cells suppress their differentiation in the absence of exogenous Wnt ligands.
Conclusions : Our findings demonstrate that tumour cell-derived ligand expression and extracellular matrix remodelling sustain Wnt signalling during DGC progression. These complementary mechanisms promote niche independence enabling expansion of undifferentiated DGC cells needed for the development of advanced tumours.
Gut 2024