Title: Cancer-associated fibroblasts: culprits or victims in cannibalism of oral squamous cell carcinoma cells?
Funder: The Academy of Medical Sciences

Abstract: The purpose of this study is to evaluate whether cancer-associated fibroblasts (CAF) promote cannibalistic activity of oral cancer cells and/or act as targets of these cells. TCC has been described for more than a century through histomorphological analyses of cell-in-cell structures in tumours. However, only in recent years, the improvement of 3D culture methods have allowed us to study the homotypic and heterotypic interactions that occur in the tumor microenvironment, associated with malignant tumour progression. Recent reports in breast cancer have provided evidence that mesenchymal stem cells, which share several features with CAF, promote TCC and malignant behaviour in 3D co-cultures. To date, little is known of the mechanisms underlying TCC in oral cancer, and nothing is known of the contribution of CAF. Given the evidence that TCC selects and/or maintains a more aggressive malignant cell population, and, knowing that CAFs represent an abundant population that plays a fundamental role in modulating malignant cell behavior, understanding the influence of CAF on TCC will reveal new aspects of oral cancer biology and could identify novel biomarkers and/or therapeutic targets. To address this, oral squamous cell carcinoma (OSCC; the most common form of oral cancer) spheroids will be established from OSCC-cell and CAF cocultures. Tumour cells and fibroblasts will be labeled with fluorescent dyes (Blue and Green, respectively) and the interaction between these cells will be studied through flow cytometry and high content screening. The identification and location of cell-in-cell structures will be performed on confocal microscopy, through immunostaining for pan-cytokeratins (epithelial phenotype cells), vimentin (mesenchymal phenotype cells) and p16INK4A (cell senescence), respectively. Next, we will evaluate the effects of the interaction between OSCC and CAF on cancer cell behaviour and their gene expression, using RNAseq and Proteomics to identify key molecular pathways involved. This will provide a platform to improve disease outcomes by developing novel therapeutic targets and prognostic biomarkers identified here in subsequent studies building on the collaboration fostered by this award.

Lay abstract: Oral (mouth) cancer is a major public health problem in Brazil and a priority of the Ministry of Health. Rates are also rising throughout the western world, including in the UK. Despite this, oral cancer is one of the least studied cancers in the world. As a result, there are limited treatment options, with surgery often being the only hope of cure; unfortunately this can have consequences such as facial deformities and problems with eating and speech. For many years, pathologists studying oral cancer have noticed the presence of what are called ‘cell-in-cell’ structures, and that these tend to be found in more aggressive (faster growing and/or spreading) tumours. Cell-in-cell structures are formed when cancer cells eat (cannibalise) other cells. This gives ‘cannibal’ cells an advantage and is thought to lead to tumours which grow faster and spread more easily. The behaviour of tumours depends on the interaction between cancer cells and other non-cancerous cells surrounding them, such as cancer-associated fibroblasts (CAF). The presence of CAF around a tumour is one of the biggest predictors, along with the presence of cannibal cells, of a tumour being more difficult to treat. In this project, we will assess whether CAFs are a target and/or promoters of cannibalism in OSCC. We think this will identify specific molecules and features of the tumours that might indicate how aggressively a tumour will behave or be targets of new drugs, improving survival and quality of life for people with oral cancer.

Research activity codes: 2.1 BIOLOGICAL AND ENDOGENOUS FACTORS
Health categories: CANCER AND NEOPLASMS