| 1. |
- Alkasalias, Twana, et al.
(författare)
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RhoA knockout fibroblasts lose tumor-inhibitory capacity in vitro and promote tumor growth in vivo
- 2017
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 114:8, s. E1413-E1421
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Tidskriftsartikel (refereegranskat)abstract
- Fibroblasts are a main player in the tumor-inhibitory microenvironment. Upon tumor initiation and progression, fibroblasts can lose their tumor-inhibitory capacity and promote tumor growth. The molecular mechanisms that underlie this switch have not been defined completely. Previously, we identified four proteins over-expressed in cancer-associated fibroblasts and linked to Rho GTPase signaling. Here, we show that knocking out the Ras homolog family member A (RhoA) gene in normal fibroblasts decreased their tumor-inhibitory capacity, as judged by neighbor suppression in vitro and accompanied by promotion of tumor growth in vivo. This also induced PC3 cancer cell motility and increased colony size in 2D cultures. RhoA knockout in fibroblasts induced vimentin intermediate filament reorganization, accompanied by reduced contractile force and increased stiffness of cells. There was also loss of wide F-actin stress fibers and large focal adhesions. In addition, we observed a significant loss of a-smooth muscle actin, which indicates a difference between RhoA knockout fibroblasts and classic cancer-associated fibroblasts. In 3D collagen matrix, RhoA knockout reduced fibroblast branching and meshwork formation and resulted in more compactly clustered tumor-cell colonies in coculture with PC3 cells, which might boost tumor stem-like properties. Coculturing RhoA knockout fibroblasts and PC3 cells induced expression of proinflammatory genes in both. Inflammatory mediators may induce tumor cell stemness. Network enrichment analysis of transcriptomic changes, however, revealed that the Rho signaling pathway per se was significantly triggered only after coculturing with tumor cells. Taken together, our findings in vivo and in vitro indicate that Rho signaling governs the inhibitory effects by fibroblasts on tumor-cell growth.
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| 2. |
- Alkasalias, Twana
(författare)
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Tumor microenvironment : the paradoxical action of fibroblasts
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The term tumor refers to an abnormal and pathological tissue characterized by a massive cell growth; it comprises various populations of transformed and malignant cells. These cells cross-communicate with each other and with different types of cells in the surrounding microenvironment. The nature of communication and interactions within the tumor microenvironment (TME) directs the fate of transformed cells via inducing pro- or antitumorigenic signals. Consequently, these cells will either succeed or fail to progress into a malignant growth phenotype. In the TME, fibroblasts are considered as one of the major cellular compartments and the primary source of non-cellular elements, including the extracellular matrix (ECM) and soluble factors. It has been shown that tumor cells can recruit fibroblasts to induce growth-stimulatory signals. On the other hand, normal fibroblasts may also act as tumor growth repressors. However, these actions have not been thoroughly addressed. The results of this thesis demonstrate the dual functionality of fibroblasts in the TME. First, we examined the phenomenon, whereby the normal fibroblasts inhibit tumor growth and development. We found that fibroblasts reduced tumor cell proliferation and motility through two sets of signals, the first set involved transmembrane proteins and the ECM. The second set was only effective after induction of the first signal, and included soluble factors secreted upon direct contact of the fibroblasts and tumor cells. Next, we uncovered the signaling pathways that were involved in the process of tumor growth inhibition and fibroblasts activation. We revealed a switch in fibroblasts from tumor suppressive cells to ones characterized by tumor stimulatory functions. Genetic ablation of the RhoA gene in fibroblasts significantly reduced tumor cell proliferation and motility in vitro, and induced tumor cell clustering in 3D-collagen matrix. Loosing of the suppressive function was accompanied by gaining a tumor inducing ability, since RhoA deficient fibroblasts enhanced tumor initiation and development by a small number of PC3 prostate cancer cells injected subcutaneously into immunodeficient mice. In addition, knocking out the RhoA gene altered the cytoskeletal organization and reduced αSMA expression in fibroblasts. These changes conferred the cells stiffer but less contractile compared to control cells. Furthermore, upon the crosstalk with tumor cells, the RhoA deficient fibroblasts overexpressed several pro-inflammatory genes encoding for IL6, IL8, CXCL1, CXCL5, and CCL5. Such a biochemical and mechanical shift in the fibroblasts reflected their protumorigenic phenotype. Using patient-derived cancer-associated fibroblasts (CAFs). We demonstrated that CAFs rescued tumor cells from apoptosis and could even enhance their growth under cis-platinum treatment. Beside the molecular mechanistic results, this thesis introduces a comprehensive quantitative live-cell imaging tool to investigate tumor cellfibroblast interactions dynamically, providing the opportunity to measure and observe cellular proliferation, motility, and phenotypic plasticity simultaneously. Taken together, the current thesis uncovers two opposite effects of fibroblasts on tumor growth. These results emphasize the demand for targeting both CAFs and tumor cells to treat and cure cancer patients and may open novel avenues for cancer prevention approaches.
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| 3. |
- Liu, Caifeng, et al.
(författare)
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A Zebrafish Model Discovers a Novel Mechanism of Stromal Fibroblast-Mediated Cancer Metastasis
- 2017
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Ingår i: Clinical Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 1078-0432 .- 1557-3265. ; 23:16, s. 4769-4779
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Cancer metastasis can occur at the early stage of tumor development when a primary tumor is at the microscopic size. In particular, the interaction of malignant cells with other cell types including cancer-associated fibroblasts (CAF) in promoting metastasis at the early stage of tumor development remains largely unknown. Here, we investigated the role of CAFs in facilitating the initial events of cancer metastasis when primary tumors were at microscopic sizes. Experimental Design: Multicolor-coded cancer cells and CAFs were coimplanted into the transparent zebrafish body and metastasis at a single-cell level was monitored in living animals. Healthy fibroblasts, tumor factor-educated fibroblasts, and CAFs isolated from various tumors were tested for their ability to facilitate metastasis. Results: We showed that CAFs promoted cancer cell metastasis at the very early stage during primary tumor development. When a primary tumor was at the microscopic size consisting of a few hundred cells, CAFs were able to hijack cancer cells for dissemination from the primary site. Surprisingly, a majority of metastatic cancer cells remained in tight association with CAFs in the circulation. Furthermore, stimulation of non-metastasis-promoting normal fibroblasts with TGF-B, FGF-2, HGF, and PDGF-BB led to acquisition of their metastatic capacity. Conclusions: Cancer metastasis occurs at the very early stage of tumor formation consisting of only a few hundred cells. CAFs are the key cellular determinant for metastasis. Our findings provide novel mechanistic insights on CAFs in promoting cancer metastasis and targeting CAFs for cancer therapy should be aimed at the early stage during cancer development. (C) 2017 AACR.
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| 4. |
- Moyano-Galceran, Lidia, et al.
(författare)
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Adaptive RSK-EphA2-GPRC5A signaling switch triggers chemotherapy resistance in ovarian cancer.
- 2020
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Ingår i: EMBO Molecular Medicine. - : EMBO. - 1757-4676 .- 1757-4684. ; 12:4
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Tidskriftsartikel (refereegranskat)abstract
- Metastatic cancers commonly activate adaptive chemotherapy resistance, attributed to both microenvironment-dependent phenotypic plasticity and genetic characteristics of cancer cells. However, the contribution of chemotherapy itself to the non-genetic resistance mechanisms was long neglected. Using high-grade serous ovarian cancer (HGSC) patient material and cell lines, we describe here an unexpectedly robust cisplatin and carboplatin chemotherapy-induced ERK1/2-RSK1/2-EphA2-GPRC5A signaling switch associated with cancer cell intrinsic and acquired chemoresistance. Mechanistically, pharmacological inhibition or knockdown of RSK1/2 prevented oncogenic EphA2-S897 phosphorylation and EphA2-GPRC5A co-regulation, thereby facilitating a signaling shift to the canonical tumor-suppressive tyrosine phosphorylation and consequent downregulation of EphA2. In combination with platinum, RSK inhibitors effectively sensitized even the most platinum-resistant EphA2high , GPRC5Ahigh cells to the therapy-induced apoptosis. In HGSC patient tumors, this orphan receptor GPRC5A was expressed exclusively in cancer cells and associated with chemotherapy resistance and poor survival. Our results reveal a kinase signaling pathway uniquely activated by platinum to elicit adaptive resistance. They further identify GPRC5A as a marker for abysmal HGSC outcome and putative vulnerability of the chemo-resistant cells to RSK1/2-EphA2-pS897 pathway inhibition.
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| 5. |
- Ujvari, Dorina, et al.
(författare)
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Prokineticin 1 is up-regulated by insulin in decidualizing human endometrial stromal cells
- 2018
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Ingår i: Journal of Cellular and Molecular Medicine (Print). - : WILEY. - 1582-1838 .- 1582-4934. ; 22:1, s. 163-172
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Tidskriftsartikel (refereegranskat)abstract
- Prokineticin 1 (PROK1), a hypoxia-regulated angiogenic factor, has emerged as a crucial regulator of embryo implantation and placentation. Dysregulation of PROK1 has been linked to recurrent pregnancy loss, pre-eclampsia, foetal growth restriction and preterm birth. These pregnancy complications are common in women with obesity and polycystic ovary syndrome, i.e. conditions associated with insulin resistance and compensatory hyperinsulinaemia. We investigated the effect of insulin on PROK1 expression during in vitro decidualization. Endometrial stromal cells were isolated from six healthy, regularly menstruating women and decidualized in vitro. Insulin induced a significant dose-dependent up-regulation of PROK1 on both mRNA and protein level in decidualizing endometrial stromal cells. This up-regulation was mediated by hypoxia-inducible factor 1-alpha (HIF1 alpha) via the phosphatidylinositol 3-kinase (PI3K) pathway. Furthermore, we demonstrated that PROK1 did not affect the viability, but significantly inhibited the migration of endometrial stromal cells and the migratory and invasive capacity of trophoblast cell lines. This in vitro study provides new insights into the regulation of PROK1 by insulin in human decidualizing endometrial stromal cells, the action of PROK1 on migration of endometrial stromal cells, as well as migration and invasion of trophoblasts. We speculate that hyperinsulinaemia may be involved in the mechanisms by which PROK1 is linked to placenta-related pregnancy complications.
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