Biology subjects

Gariboldi, M.

Publications and source records attributed to Gariboldi, M..

4 recordsLinked to original sources

bioRxiv2022

The nanomechanical fingerprint of colorectal-derived peritoneal metastasis

Peritoneal metastases (PM) are one of the most common routes of dissemination for colorectal cancer (CRC) and remain a lethal disease with a poor prognosis. The compositional, mechanical and structural properties of the extracellular matrix (ECM) play an important role in cancer development; studying how these properties change during the progression of the disease is crucial to understand CRC-PM development. The elastic properties of ECMs derived from human samples of normal and neoplastic PM in different pathological conditions were studied by atomic force microscopy (AFM); results were correlated to patients clinical data and to the expression of ECM components related to metastatic spread. Our results show that PM progression is accompanied by stiffening of ECM as a common feature; spatially resolved mechanical analysis highlighted significant spatial heterogeneity of the elastic properties of both normal and neoplastic ECMs, which show significant overlap in the two conditions. On the micrometre scale, ECMs that are considered normal according to the pathological classification possess stiffer spatial domains, which are typically associated with cancer associated fibroblasts (CAF) activity and tumour development in neoplastic matrices; on the other hand, softer regions are found in neoplastic ECMs on the same scales. Our results support the hypothesis that local changes (stiffening) in the normal ECM can create the ground for growth and spread from the tumour of invading metastatic cells. Mechanical changes correlate well with the presence of CAF and an increase in collagen deposition, which are well known markers of cancer progression. Furthermore, we have found correlations between the mechanical properties of the ECM and patients clinical data like age, sex, presence of mutations in BRAF and KRAS genes and tumour grade. Overall, our findings suggest that the mechanical phenotyping of the PM-ECM has the potential for predicting tumour development.

biophysics↗

bioRxiv2022

Gut microbiota composition in colorectal cancer patients is genetically regulated

The risk of colorectal cancer (CRC) depends on environmental and genetic factors. Among environmental factors, an imbalance in the gut microbiota can increase CRC risk. Also, microbiota is influenced by host genetics. However, it is not known if germline variants influence CRC development by modulating microbiota composition. We investigated germline variants associated with the abundance of bacterial populations in the normal (non-involved) colorectal mucosa of 93 CRC patients and evaluated their possible role in disease. Using a multivariable linear regression, we assessed the association between germline variants identified by genome wide genotyping and bacteria abundances determined by 16S rRNA gene sequencing. We identified 37 germline variants associated with the abundance of the genera Bacteroides, Ruminococcus, Akkermansia, Faecalibacterium and Gemmiger and with alpha diversity. These variants are correlated with the expression of 58 genes involved in inflammatory responses, cell adhesion, apoptosis and barrier integrity. Genes and bacteria appear to be involved in the same processes. In fact, expression of the pro-inflammatory genes GAL, GSDMD and LY6H was correlated with the abundance of Bacteroides, which has pro-inflammatory properties; abundance of the anti-inflammatory genus Faecalibacterium correlated with expression of KAZN, with barrier-enhancing functions. Both the microbiota composition and local inflammation are regulated, at least partially, by the same germline variants. These variants may regulate the microenvironment in which bacteria grow and predispose to the development of cancer. Identification of these variants is the first step to identifying higher-risk individuals and proposing tailored preventive treatments that increase beneficial bacterial populations. Authors summaryGenetic variants describe the variation in the DNA sequence in our genomes and are unique for each person. These variants modify the risk of developing colorectal cancer (CRC) by regulating genes that participate in CRC-associated mechanisms. CRC risk is also affected by microbiota (the microorganisms residing in ourselves). A balanced microbiota helps perform our normal body functions, but can induce cancer, if this balance is lost. Microbiota is affected by factors such as pollution and diet, but is also regulated by genetic variants. However, can genetic variants predispose to cancer risk by regulating microbiota? To answer this question, we sequenced the genetic variants of 93 CRC patients and examined the composition of their intestinal microbiota. We identified variants that regulate the presence of benefic or pathogenic bacteria. The same variants also affect the expression of genes that participate in inflammation, immunity and integrity of intestinal tissue. We found that genetic variants regulate gene expression and microbiota at the same time, predisposing to a higher or lower CRC risk. People with variants predisposing to a higher risk may be benefitted by tailored preventive treatments that increase beneficial bacteria.

genetics↗

bioRxiv2022

Force sensing on cells and tissues by atomic force microscopy

Biosensors are aimed to detect tiny physical and chemical stimuli in biological systems. Physical forces are ubiquitous, being implied in all cellular processes, including cell adhesion, migration, and differentiation. Given the strong interplay between cells and their microenvironment, the extracellular matrix (ECM), the structural and mechanical properties of the ECM play an important role in the transmission of external stimuli to single cells within the tissue. Vice versa, also cells themselves use self-generated forces to probe the biophysical properties of the ECM. ECM mechanics influences cell fate, regulates tissue development and show peculiar features in health and disease conditions of living organisms. Force sensing in biological systems is therefore crucial to dissect and understand complex biological processes, such as mechanotransduction. Atomic Force Microscopy (AFM), which can both sense and apply forces at the nanoscale, with sub-nanoNewton sensitivity, represents an enabling technology and a crucial experimental tool in biophysics and mechanobiology. In this work, we report on the application of AFM to study of biomechanical fingerprints of different components of biological systems, such as the ECM, the whole cell, and cellular components, like the nucleus and the glycocalyx. We show that physical observables like the (spatially resolved) Youngs modulus of elasticity of ECMs or cells, and the effective thickness and stiffness of the glycocalyx, can be quantitatively characterised by AFM. Their modification can be correlated to changes of the microenvironment, physio-pathological conditions, or gene regulation.

biophysics↗

bioRxiv2021

Decellularized Normal and Tumor Scaffolds for Cancer Organoid Cultures as a Model of Colorectal Peritoneal Metastases

Peritoneal metastases (PM) from colorectal cancer (CRC) are associated with poor survival. The extracellular matrix (ECM) plays a fundamental role in modulating the homing of CRC metastases to the peritoneum. The mechanisms underlying the interactions between metastatic cells and the ECM, however, remain poorly understood and the number of in vitro models available for the study of the peritoneal metastatic process is limited. Here, we show that decellularized ECM of the peritoneal cavity allows the growth of organoids obtained from PM, favoring the development of three-dimensional nodules that maintain the characteristics of in vivo PM. Organoids preferentially grow on scaffolds obtained from neoplastic peritoneum, which are characterized by greater stiffness than normal scaffolds. A gene expression analysis of organoids grown on different substrates reflected faithfully the clinical and biological characteristics of the organoids. An impact of the ECM on the response to standard chemotherapy treatment for PM was also observed. SignificanceEvidence of the value of ex vivo 3D models obtained by combining patient-derived extracellular matrices depleted of cellular components and organoids to mimic the metastatic niche, to be used as a tool to develop new therapeutic strategies in a biologically relevant context, to personalize treatments and increase their efficacy.

cancer biology↗