Periodic Reporting for period 1 - FiBRO (Fibroblasts in the Biology of Rectal Cancer Progression)
Reporting period: 2016-05-01 to 2018-04-30
The main aim of the Marie Curie IF-FIBRO project was to elucidate the molecular changes that CRT could be exerting on the tumor stroma, particularly in the population of Cancer Associated Fibroblasts or CAFs. This, with the goal of understanding how stromal modifications can alter tumor development and aggressiveness and patient’s prognosis. Increasing knowledge in the process of tumor progression will have a clear impact in future’s medicine and society as it will determine the development of new diagnostic markers and targeted cancer therapies.
Description of main results so far
I have performed primary cultures from fibroblasts (CAFs and normal fibroblasts, NAFs) from 9 different rectal cancer patients, before and after radiotherapy. From those samples, I have obtained both intracellular protein extracts. Also, I have generated a system to purify extracellular matrix proteins from the primary cultures. In this system, cells are always plated on a soft substrate (30KPa), thus preventing the normal CAFs from getting activated. Together with the proteomics facility in Curie, we have performed proteomics for the samples available so far. Although this work is not finished yet, preliminary results point to a specific pattern of matrix protein expression in CAFs after radiotherapy.
Fibronectin (FN1) was among one of the most CAF expressed proteins. We have found that this protein plays an important role in the process of tumor metastasis, particularly in the process of circulating tumor cell (CTC) extravasation. Especially in tumor bearing mice, fibronectin was present in the form of aggregates attached to the walls of hepatic blood vessels. This specific location facilitates the attachment of CTCs and their extravasation to form new metastatic lesions. Indeed, cancer cells expressing Talin1, a protein that is involved in the formation of focal adhesions (structures used by the cells to attach Fibronectin), was key to allow CTC attachment to this fibronectin-based structures. Patients having higher levels of Talin1 in CTCs, showed a worse prognostic compared with those expressing less Talin1. In this work (Barbazan et al, Cancer Research, 2017), we concluded that both focal adhesion proteins in cancer cells, as well as hepatic fibronectin, could confer new targets against tumor dissemination.
Moreover, we have developed other methods to study tumor cell migration and invasion in 3D (Staneva R, Barbazan J, et al, Methods Mol Biol, 2018). Using some of these systems, we have evaluated how CAFs (pre and post-CRT) determine tumor invasion and stemness properties. Although these results have not been published yet, preliminary results point towards a cancer cell stemness promoting phenotype after radiotherapy.
References
- Barbazán J, Alonso-Alconada L, Elkhatib N, Geraldo S, Gurchenkov V, Glentis A, Van Niel G, Palmulli R, Fernández B, Viano P, Garcia-Caballero T, Lopez-Lopez R, Abal M & Vignjevic D. Liver metastasis is facilitated by the adherence of circulating tumor cells to vascular fibronectin deposits. Cancer Research, 2017. DOI: 10.1158/0008-5472.CAN-16-1917
- Staneva R, Barbazan J, Simon A, Vignjevic DM, Krndja D. Cell migration in tissues: Explant culture and live imaging. Methods Mol Biol, 2018.
DOI: 10.1007/978-1-4939-7701-7_13.
The final results of FiBRO will determine the global role of CRT-derived CAFs in the behavior of cancer cells, and we expect the generation of new markers for therapy resistance evaluation, and possibly new therapeutic targets that could be tested.