The tumor microenvironment in liver metastases from colorectal cancer in the context of histologic growth patterns
[eng] Colorectal cancer (CRC) is the third most frequent cancer type in the world and the second cause of death because of cancer. Nowadays, 25% of cases are diagnosed at the metastatic stage (mCRC), and 20-25% of the remaining patients develop metastases during the disease course. Patients with mCR...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2023 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/222516 |
| Acceso en línea: | https://hdl.handle.net/2445/222516 http://hdl.handle.net/10803/694928 |
| Access Level: | acceso abierto |
| Palabra clave: | Histopatologia Immunologia Càncer colorectal Metàstasi Fibroblasts Pathological histology Immunology Colorectal cancer Metastasis |
| Sumario: | [eng] Colorectal cancer (CRC) is the third most frequent cancer type in the world and the second cause of death because of cancer. Nowadays, 25% of cases are diagnosed at the metastatic stage (mCRC), and 20-25% of the remaining patients develop metastases during the disease course. Patients with mCRC have a poor prognosis, as the 5-year survival rate for mCRC is less than 20%. Most CRC metastases appear in the liver (CRLM), for which the only curative treatment is surgery. However, only 30% of patients are suitable for resection. The remaining 70% can only be treated with chemotherapy in combination or not with immunotherapy. This last one has shown discouraging results in the last clinical trials. In view of all this, there is a need for further research in the biology and in new therapeutic strategies focused on CRC liver. CRLMs are characterized by their way of growing in the host organ, as they show three histologic growth patterns (HGPs): desmoplastic, replacement and pushing. The desmoplastic pattern shows a fibrotic rim that separates tumor glands from liver parenchyma. On contrary, in replacement HGP, tumoral cells are in direct contact with hepatocytes. As the pushing pattern is the less common, the classification is usually simplified in desmoplastic (dHGP) and non-desmoplastic (non-dHGP) HGPs. These patterns have different biological aspects. However, their value is due to their utility as a prognostic and predictive marker, as dHGP has been associated with better patient outcomes, as well as a better response to anti-angiogenic treatments. In our study, we aimed to further characterize the biology of CRLM HGPs. As no features of primary tumoral cells have been associated with the appearance of each HGP, we postulated that tumor microenvironment factors may be underlying the observed differences in prognoses. Because of that, in our project, we focused on immune infiltrates and cancer associated fibroblasts present in each HGP. Concerning immune infiltrates, multiplex immunofluorescence (mIHC) let us investigate both lymphoid and myeloid cell subsets in a tissue microarray of 100 CRLM patients. Our results revealed an immunologically active anti-tumoral environment in dHGP, constituted by higher densities of cytotoxic T cells interacting with tumoral cells. On the other hand, higher levels of macrophages, both M1 and M2 polarized, as well as other pro-tumoral cell subsets like Th2 lymphoid cells, non-macrophage CD163+ cells and Calprotectin+ cells, were at higher densities in non-dHGP, suggesting a pro-tumoral immune environment in this HGP. Through mIHC we also investigated several cancer associated fibroblasts (CAFs) subpopulations. Our results showed an enrichment of several COL1A1 expressing CAF subsets in dHGP. This protein from the extracellular matrix is associated with tumor growth restraining and an immune-active environment. Through in vitro experiments, we investigated the two main precursor cells that can give rise to activated fibroblasts in the liver: hepatic stellate cells (HSCs) and portal fibroblasts (PFs). We studied the changes at RNA level of both HSCs and PFs when activated by their co-culture with tumoral cells. The RNAseq results obtained showed differences between i) mesenchymal cells when co-cultured with tumoral cells ii) and the co-cultured conditions when compared when the corresponding monocultures. Moreover, we identified two useful markers to distinguish PF-derived CAFs, MFAP5, and HSC-derived CAFs, F2R. At functional level, PFs showed a higher capacity for recruiting Th2 cells and induce higher proliferation rates in tumor cells. We also assessed in vitro the function of CD90 marker through two subpopulations of CAFs isolated from the same patient, CD90hi and CD90lo, that had shown differences in their secretome. CD90hi cells showed higher expression of Podoplanin, which is associated to macrophage recruiting and M2 polarization. Our assays showed higher capacity of CD90hi cells to recruit monocytes, as well as to polarize them to an M2 phenotype. Altogether, the results of this thesis describe an immune active environment in dHGP and a pro-tumoral immune environment in non-dHGP, which could explain the failure of immunotherapy. This conclusion suggests a need for patient segregation according to HGP and proposes new targets for CRLM treatment. Moreover, both the results obtained about immune infiltrates and cancer associated fibroblasts open doors for interesting new research lines that could lead to understanding the biology underlying the prognostic value of HGPs as well as proposing new therapeutic targets for these patients. |
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