Elvira Olaso

Impaired dermal wound healing in discoidin domain receptor 2-deficient mice associated with defective extracellular matrix remodeling

BackgroundThe wounding response relies on tightly regulated crosstalk between recruited fibroblasts and the collagenous extracellular matrix (ECM). Discoidin domain receptor 2 (DDR2) is a tyrosine kinase receptor for fibrillar collagen expressed during pathologic scarring, for example wound healing, arthritis and cancer. We have previously shown that DDR2 phosphorylation drives key wounding responses in skin fibroblasts including proliferation, chemotactic migration and secretion of both metalloproteinases and fibrillar collagen. In this study we compared healing of cutaneous wounds in DDR2+/+ and DDR2-/- mice and analyzed specific fibroblast responses.ResultsCutaneous wound healing was significantly delayed in DDR2-/- mice compared with DDR2+/+ animals. Reduced α-smooth muscle actin (αSMA) expression and matrix metalloproteinase 2 (MMP2) activity in the DDR2-/- wound extracts indicated defective recruitment of skin fibroblasts. DDR2-/- wounds showed decreased tensile strength during healing, which correlated with a significant reduction in collagen content and defective collagen crosslinking. Non-wounded skin in DDR2-/- mice expressed less mRNA of the crosslinking enzymes lysyl oxidase (LOX), lysyl hydroxylase1 (LH1) and matricellular secreted protein, acidic and rich in cysteine (SPARC; also known as osteonectin). Skin fibroblasts isolated from DDR2-/- mice displayed altered mRNA expression of a cluster of collagens, proteoglycans, integrins and MMPs that have been previously correlated with DDR2 expression, and reduced LOX, LH1 and SPARC mRNA levels and proteins. Stable reconstitution of wild-type DDR2 by retroviral infection restored LOX, LH1 and SPARC mRNA and protein levels in DDR2-/- fibroblasts. Contraction of collagen gels was reduced in DDR2-/- fibroblasts, accompanied by significantly reduced phosphorylated SrcY418. Inhibition of either LOX activity by β-aminoproprionitrile or MMP activity by N-[(2R)-2-(hydroxamido carbonylmethyl)-4-methylpentanoyl]-l-tryptophan methylamide (GM6001) reduced collagen gel contraction by skin fibroblasts after DDR2 induction with soluble collagen type I.ConclusionsDDR2 contributes to skin fibroblast responses during tissue injury. Defective synthesis of collagen type I, crosslinking molecules and MMP2 predispose DDR2-/- mice to defective dermal wounding.

Mannose receptor-mediated endothelial cell activation contributes to B16 melanoma cell adhesion and metastasis in liver

The role of mannose receptors from hepatic sinusoidal endothelium (HSE) in liver colonization by B16 melanoma (B16M) cells was studied. The expression of high mannose‐type oligosaccharides on the surface of B16M cells was enhanced by in vitro treatment with 1‐deoximannojirimycin (1‐DMM). There was a significant (P < 0.01) enhancement of hepatic metastasis when B16M cells were 1‐DMM‐treated before being intrasplenically injected into C57BL/6J mice. Intraperitoneal administration of 5 mg/kg recombinant human interleukin‐1 receptor antagonist (rHuIL‐1Ra) inhibited the 1‐DMM‐induced enhancement of metastasis. Expression of high mannose‐type oligosaccharides on the surface of 1‐DMM‐treated B16M cells and their in vitro adhesion to the HSE was significantly correlated (R = 0.82). The addition of either 100 μg/ml mannan or paraformaldehyde (PFA)‐fixed 1‐DMM‐treated B16M cells to cultured HSE for a period of 12 h significantly (P < 0.01) increased the release of IL‐1β from the HSE compared to that liberated by the HSE incubated with either basal medium or PFA‐fixed untreated B16M cells. The same HSE treatments also significantly (P < 0.01) increased the degree of adhesion of other B16M cells to HSE, being abrogated by anti‐mouse vascular cell adhesion molecule‐1 (VCAM‐1) antibodies. The conditioned media from HSE cultures, activated by PFA‐fixed, 1‐DMM‐treated B16M cells significantly (P < 0.01) increased B16M cell proliferation when compared to conditioned media from HSE cultures incubated with PFA‐fixed, untreated B16M cells. Thus, 1‐DMM treatment of B16M cells enhanced the development of hepatic metastasis by IL‐1‐dependent mechanisms. The mechanism is consistent with in vitro mannose receptor‐mediated melanoma cell attachment to the HSE, which subsequently upregulates IL‐1β release, VCAM‐1‐dependent adherence, and melanoma growth factor(s) release by HSE. J. Cell. Physiol. 174:322–330, 1998.

Resveratrol prevents inflammation-dependent hepatic melanoma metastasis by inhibiting the secretion and effects of interleukin-18

BackgroundImplantation and growth of metastatic cancer cells at distant organs is promoted by inflammation-dependent mechanisms. A hepatic melanoma metastasis model where a majority of metastases are generated via interleukin-18-dependent mechanisms was used to test whether anti-inflammatory properties of resveratrol can interfere with mechanisms of metastasis.MethodsTwo experimental treatment schedules were used: 1) Mice received one daily oral dose of 1 mg/kg resveratrol after cancer cell injection and the metastasis number and volume were determined on day 12. 2) Mice received one daily oral dose of 1 mg/kg resveratrol along the 5 days prior to the injection of cancer cells and both interleukin-18 (IL-18) concentration in the hepatic blood and microvascular retention of luciferase-transfected B16M cells were determined on the 18th hour. In vitro, primary cultured hepatic sinusoidal endothelial cells were treated with B16M-conditioned medium to mimic their in vivo activation by tumor-derived factors and the effect of resveratrol on IL-18 secretion, on vascular cell adhesion molecule-1 (VCAM-1) expression and on tumor cell adhesion were studied. The effect of resveratrol on melanoma cell activation by IL-18 was also studied.ResultsResveratrol remarkably inhibited hepatic retention and metastatic growth of melanoma cells by 50% and 75%, respectively. The mechanism involved IL-18 blockade at three levels: First, resveratrol prevented IL-18 augmentation in the blood of melanoma cell-infiltrated livers. Second, resveratrol inhibited IL-18-dependent expression of VCAM-1 by tumor-activated hepatic sinusoidal endothelium, preventing melanoma cell adhesion to the microvasculature. Third, resveratrol inhibited adhesion- and proliferation-stimulating effects of IL-18 on metastatic melanoma cells through hydrogen peroxide-dependent nuclear factor-kappaB translocation blockade on these cells.ConclusionsThese results demonstrate multiple sites for therapeutic intervention using resveratrol within the prometastatic microenvironment generated by tumor-induced hepatic IL-18, and suggest a remarkable effect of resveratrol in the prevention of inflammation-dependent melanoma metastasis in the liver.

Discoidin domain receptor 2 deficiency predisposes hepatic tissue to colon carcinoma metastasis

Background The transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts is a major mechanism for stroma development in hepatic metastasis, but their regulatory pathways remain unclear. Transdifferentiated HSCs from fibrotic liver express high levels of the fibrillar collagen receptor discoidin domain receptor 2 (DDR2), but it is unclear if DDR2 plays a direct profibrogenic role in the tumour microenvironment. Aim To assess the impact of DDR2 on the prometastatic role of HSC-derived myofibroblasts. Methods Hepatic metastases were induced in DDR2−/− and DDR2+/+ mice by intrasplenic injection of MCA38 colon carcinoma cells, and their growth and features were characterised. Stromagenic, angiogenic and cancer cell proliferation responses were quantified in metastases by immunohistochemistry. The adhesion-, migration- and proliferation-stimulating activities of supernatants from primary cultured DDR2−/− and DDR2+/+ HSCs, incubated in MCA38 cell-conditioned medium, were evaluated in primary cultured liver sinusoidal endothelium cells (LSECs) and MCA38 cells. Gene expression signatures from freshly isolated DDR2−/− and DDR2+/+ HSCs were compared and DDR2-regulated genes were studied by RT-PCR under basal conditions and after stimulation with MCA38 tumour-conditioned media. Results Metastases were increased three fold in DDR2−/− livers, and contained a higher density of α−smooth muscle actin-expressing myofibroblasts, CD31-expressing microvessels and Ki67-expressing MCA38 cells than metastases in DDR2+/+ livers. Media conditioned by MCA38-activated DDR2−/− HSCs significantly increased adhesion, migration and proliferation of LSECs and MCA38 cells, compared with DDR2+/+ HSCs. DDR2 deficiency in HSCs led to decreased gene expression of interferon γ-inducing factor interleukin (IL)-18 and insulin-like growth factor-I; and increased gene expression of prometastatic factors IL-10, transforming growth factor (TGF)β and vascular endothelial growth factor (VEGF), bone morphogenetic protein-7 and syndecan-1. MC38 tumour-conditioned media further exacerbated expression changes in DDR2-dependent IL-10, TGFβ and VEGF genes. Conclusion DDR2 deficiency fosters the myofibroblast transdifferentiation of tumour-activated HSCs, generating a prometastatic microenvironment in the liver via HSC-derived factors. These findings underscore the role of stromal cells in conditioning the hepatic microenvironment for metastases through altered receptor–stroma interactions.

Downregulation of discoidin domain receptor 2 in A375 human melanoma cells reduces its experimental liver metastasis ability

Discoidin domain receptors (DDR1 and DDR2) are tyrosine kinase receptors for fibrillar collagen implicated in postnatal development, tissue repair, and primary and metastatic cancer progression. While DDR1 has been described in tumor cells, DDR2 has been localized in the tumor stroma, but its presence in the tumor cells remains unknown. The aim of this study was to elucidate the role of DDR2 signaling in tumor cells during hepatic metastasis progression. DDR2 expression and phosphorylation in cultured human A375 melanoma cells was documented by Western blot analysis. A375 cells were stably transfected with a small interfering RNA (siRNA) against DDR2 and two clones were selected: A375R2-70 and A375R2-40, with 70 and 40% of the DDR2 protein expression respectively, compared to mock-transfected cells (A375R2-100). Development of experimental liver metastasis by intrasplenic inoculation of A375R2-70 and A37R2-40 clones was reduced by 60 and 75%, respectively, measured as tumor volume, compared to livers injected with A375R2-100 cells. Accordingly, A375R2-70 and A37R2-40 clones showed reduced in vitro gelatinase activity and JNK phosphorylation, compared to mock transfected cells, with maximal inhibition in A375R2-40. Additionally, A375 melanoma, SK-HEP hepatoma and HT-29 colon carcinoma human cell lines transiently transfected with siRNA against DDR2 also showed reduced proliferation and migration rates compared to mock-transfected ones. In conclusion, DDR2 promotes A375 melanoma metastasis to the liver and the underlying mechanism implicates regulation of metalloproteinase release, cell growth and chemotactic invasion of the host tissue.

Role of discoidin domain receptor 2 in wound healing.

Until recently, collagen interactions with cells had been ascribed to integrins. The identification of the Discoidin Domain Receptor (DDR) family as collagen receptors represents a new paradigm in the regulation of collagen-cell interactions. How DDR signaling is biochemically linked to specific cell regulatory functions remains largely unknown. Moreover, the characteristic slow and substained phosphorylation of DDRs and the elevated expression of DDR2 in the myofibroblasts of healing wounds suggest a role for DDR2 in physiological and pathological wound healing. In fact, DDR2 signaling regulates cell proliferation and extracellular matrix synthesis, which are key aspects of fibroblast contribution to tissue healing. In this review we summarize evidence in favor of this concept.

Abstract B10: LFA-1/ICAM-1 interaction switches on an orchestrated prometastatic microenvironmental shift during experimental liver metastasis of colon C26 cancer cells.

Intercellular adhesion molecule (ICAM)-1 is the main counter-receptor for the lymphocyte function associated antigen (LFA)-1. However, the role this interaction plays during liver metastasis of colorectal cancer cells and its underlying mechanisms remain unclear. Previously, we showed that mannose receptor (ManR) stimulation on liver sinusoidal endothelial cells (LSECs) resulted in a reduced cytotoxic potential of liver infiltrating lymphocytes (LIL) towards C26 murine colon carcinoma cells. Using ICAM-1 specific siRNAs in vivo, we aimed to study the role of hepatic ICAM-1 in the prometastatic shift of the liver microenvironment. Livers of control and silenced mice, 24 hours and 14 days after C26 cell inoculation, were compared for: percentage of detained C26 cells, number and volume of metastatic foci, levels of recruited immune, myofibroblastic and inflammatory cells and whole liver expression of pro-inflammatory genes. Detained cancer cells and metastatic foci number were reduced in silenced mice compared to controls, along with a decrease in myeloid suppressor cells and recruited macrophages and myofibroblasts. On the contrary, significant higher numbers of lymphocytic cells were observed in mice with reduced ICAM-1. Finally, silencing of ICAM1 resulted in altered total liver mRNA levels of proinflammatory factors in the tumor-bearing mice. Therefore, an orchestrated prometastatic program might be switched on in the liver microenvironment by LFA-1/ICAM-1 interaction which, in turn, could lead not only to a reduced antitumor citotoxicity but, also, to activation of the stromal compartment favoring tumor progression, and, opening liver9s doors to tumor cells to aggressively metastasize. Based on these results, LFA-1/ICAM-1 interaction arises as a potential therapeutic target in cancer treatment. Citation Format: Aitor Benedicto, Joana Marquez, Elvira Olaso, Beatriz Arteta. LFA-1/ICAM-1 interaction switches on an orchestrated prometastatic microenvironmental shift during experimental liver metastasis of colon C26 cancer cells.. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr B10. doi:10.1158/1538-7445.CHTME14-B10

Decreased expression of the β 2 integrin on tumor cells is associated with a reduction in liver metastasis of colorectal cancer in mice

BackgroundLymphocyte Function-Associated Antigen-1 (LFA-1; CD18/CD11a) is one of the main adhesion molecules used by immune cells to infiltrate the liver under inflammatory conditions. Recently, the expression of this integrin has also been reported on several solid tumors, including colorectal cancer. However, its functional role in the metastatic progression to the liver remains unknown. Using in vitro assays and an experimental orthotopic in vivo model of liver metastasis, we aimed to elucidate the role of tumor LFA-1 in the metastatic progression by means of the partial depletion of the β2 subunit of LFA-1, required for integrin activation, firm adhesion and signaling.MethodsTo do so, we evaluated the effects of β2 reduction on the murine colon carcinoma C26 cell line on their pro-metastatic features in vitro and their metastatic potential in vivo in a mouse model of colon carcinoma metastasis to the liver.ResultsThe reduction in β2 integrin expression correlated with a slower proliferation, and a reduced adhesion and migration of C26 cells in an in vitro setting. Additionally, tumor cells with a reduced in β2 integrin expression were unable to activate the liver sinusoidal endothelial cells (LSECs). This resulted in a recovery of the cytotoxic potential of liver lymphocytes which is compromised by LSECs activated by C26 cells. This was related to the abrogation of RNA expression of inflammatory and angiogenic cytokines by C26 cells after their activation with sICAM-1, the main ligand of β2αL. Furthermore, in vivo tumor cell retention and metastasis were profoundly reduced, along with a decrease in the recruitment and infiltration of myeloid derived suppressor cells (MDSCs) and lymphocytes to the liver.ConclusionTaken together, our findings uncovered the modulatory role for the tumor β2 subunit of the LFA-1 integrin in the metastatic progression of colorectal cancer to the liver by impairing activation of liver endothelium and thus, the local immune response in the liver. Besides, this integrin also showed to be critical in vivo for tumor cell retention, cytokine release, leukocyte recruitment and metastasis development. These data support a therapeutical potential of the integrin LFA-1 as a target for the treatment of colorectal liver metastasis.

Discoidin Domain Receptors in Liver Fibrosis

Hepatic fibrosis results from an altered balance of extracellular matrix (ECM) synthesis and degradation that is skewed toward an accumulation of a collagenous ECM following chronic injury. Fibrosis from persistent injury may progress to cirrhosis, an end-stage lesion, which may lead to liver failure and death. Research is focused on receptor tyrosine kinases (RTKs) as new targets for antifibrotic therapies. Among them, discoidin domain receptors (DDRs) attract much attention because they represent a new paradigm of RTK signaling in response to ECM instead of soluble factors.