Alessia Brossa

TRPV4 mediates tumor-derived endothelial cell migration via arachidonic acid-activated actin remodeling

Changes in intracellular calcium [Ca2+]i levels control critical cytosolic and nuclear events that are involved in the initiation and progression of tumor angiogenesis in endothelial cells (ECs). Therefore, the mechanism(s) involved in agonist-induced Ca2+i signaling is a potentially important molecular target for controlling angiogenesis and tumor growth. Several studies have shown that blood vessels in tumors differ from normal vessels in their morphology, blood flow and permeability. We had previously reported a key role for arachidonic acid (AA)-mediated Ca2+ entry in the initial stages of tumor angiogenesis in vitro. In this study we assessed the mechanism involved in AA-induced EC migration. We report that TRPV4, an AA-activated channel, is differentially expressed in EC derived from human breast carcinomas (BTEC) as compared with ‘normal’ EC (HMVEC). BTEC display a significant increase in TRPV4 expression, which was correlated with greater Ca2+ entry, induced by AA or 4αPDD (a selective TRPV4 agonist) in the tumor-derived ECs. Wound-healing assays revealed a key role of TRPV4 in regulating cell migration of BTEC but not HMVEC. Knockdown of TRPV4 expression completely abolished AA-induced BTEC migration, suggesting that TRPV4 mediates the pro-angiogenic effects promoted by AA. Furthermore, pre-incubation of BTEC with AA induced actin remodeling and a subsequent increase in the surface expression of TRPV4. This was consistent with the increased plasma membrane localization of TRPV4 and higher AA-stimulated Ca2+ entry in the migrating cells. Together, the data presented herein demonstrate that: (1) TRPV4 is differentially expressed in tumor-derived versus ‘normal’ EC; (2) TRPV4 has a critical role in the migration of tumor-derived but not ‘normal’ EC migration; and (3) AA induces actin remodeling in BTEC, resulting in a corresponding increase of TRPV4 expression in the plasma membrane. We suggest that the latter is critical for migration of EC and thus in promoting angiogenesis and tumor growth.

Resident Stem Cells and Renal Carcinoma

According to the cancer stem cell hypothesis tumors are maintained by a cancer stem cell population which is able to initiate and maintain tumors. Tumor-initiating stem cells display stem or progenitor cell properties such as self-renewal and capacity to re-establish tumors that recapitulate the tumor of origin. In this paper, we discuss data relative to the presence of cancer stem cells in human renal carcinoma and their possible origin from normal resident stem cells. The cancer stem cells identified in human renal carcinomas are not derived from the normal CD133+ progenitors of the kidney, but rather from a more undifferentiated population that retains a mesenchymal phenotype. This population is able to self-renewal, clonogenicity, and in vivo tumor initiation. Moreover, they retain pluripotent differentiation capability, as they can generate not only the epithelial component of the tumor, but also tumor endothelial cells. This suggests that renal cancer stem cells may contribute to the intratumor vasculogenesis.

The angiostatic molecule Multimerin 2 is processed by MMP-9 to allow sprouting angiogenesis

Angiogenesis is a crucial process occurring under physiological and pathological conditions, including cancer. The development of blood vessels is tightly regulated by a plethora of cytokines, endothelial cell (EC) receptors and extracellular matrix (ECM) components. In this context, we have shown that Multimerin 2 (MMRN2), an ECM molecule specifically secreted by ECs, exerts angiostatic functions by binding VEGFA and other pro-angiogenic cytokines. Here, we demonstrate that during angiogenic stimuli MMRN2 mRNA levels significantly decrease. Furthermore, we provide evidence that MMRN2 is processed by matrix metalloproteinases (MMPs) including MMP-9 and, to a lesser degree, by MMP-2. This proteolytic cleavage correlates with an increased migration of ECs. Accordingly, MMRN2 down-regulation is associated with an increased number of EC pseudopodia at the migrating front and this effect is attenuated using specific MMP-9 inhibitors. The down-modulation of MMRN2 occurs also in the context of tumor-associated angiogenesis. Immunofluorescence performed on tumor sections indicate a broad co-localization of MMP-9 and MMRN2, suggesting that the molecule may be extensively remodeled during tumor angiogenesis. Given the altered expression in tumors and the key role of MMRN2 in blood vessel function, we postulate that analyses of its expression may serve as a marker to predict the efficacy of the treatments. In conclusion, these data further support the role of MMRN2 as a key molecule regulating EC function and sprouting angiogenesis.

Differential sensitivity of prostate tumor derived endothelial cells to sorafenib and sunitinib

BackgroundProstate cancer is the second leading cause of male cancer death in developed countries. Although the role of angiogenesis in its progression is well established, the efficacy of anti-angiogenic therapy is not clearly proved. Whether this could depend on differential responses between tumor and normal endothelial cells has not been tested.MethodsWe isolated and characterized three lines of endothelial cells from prostate cancer and we tested the effect of Sunitinib and Sorafenib, and the combined treatment with the anti-androgen Casodex, on their angiogenic functions.ResultsEndothelial cells isolated from prostate tumors showed angiogenic properties and expression of androgen and vascular endothelial cell growth factor receptors. Sunitinib affected their proliferation, survival and motility while Sorafenib only showed a minor effect. At variance, Sunitinib and Sorafenib showed similar cytotoxic and anti-angiogenic effects on normal endothelial cells. Sorafenib and Sunitinib inhibited vascular endothelial cell growth factor receptor2 phosphorylation of prostate cancer endothelial cells, while they differentially modulated Akt phosphorylation as no inhibitory effect of Sorafenib was observed on Akt activation. The combined treatment of Casodex reverted the observed resistance to Sorafenib both on cell viability and on Akt activation, whereas it did not modify the response to Sunitinib.ConclusionsOur study demonstrates a resistant behavior of endothelial cells isolated from prostate cancer to Sorafenib, but not Sunitinib. Moreover, it shows the benefit of a multi-target therapy combining anti-angiogenic and anti-hormonal drugs to overcome resistance.

Role of CD133 Molecule in Wnt Response and Renal Repair

Renal repair after injury is dependent on clonal expansion of proliferation‐competent cells. In the human kidney, the expression of CD133 characterizes a population of resident scattered cells with resistance to damage and ability to proliferate. However, the biological function of the CD133 molecule is unknown. By RNA sequencing, we found that cells undergoing cisplatin damage lost the CD133 signature and acquired metanephric mesenchymal and regenerative genes such as SNAIL1, KLF4, SOX9, and WNT3. CD133 was reacquired in the recovery phase. In CD133‐Kd cells, lack of CD133 limited cell proliferation after injury and was specifically correlated with deregulation of Wnt signaling and E‐cadherin pathway. By immunoprecipitation, CD133 appeared to form a complex with E‐cadherin and β‐catenin. In parallel, CD133‐Kd cells showed lower β‐catenin levels in basal condition and after Wnt pathway activation and reduced TCF/LEF promoter activation in respect to CD133+ cells. Finally, the lack of CD133 impaired generation of nephrospheres while favoring senescence. These data indicate that CD133 may act as a permissive factor for β‐catenin signaling, preventing its degradation in the cytoplasm. Therefore, CD133 itself appears to play a functional role in renal tubular repair through maintenance of proliferative response and control of senescence. Stem Cells Translational Medicine 2018;7:283–294

Presence of osteoinductive factors in bovine colostrum

New approaches in the treatment of skeletal defects may benefit from the use of soluble biological factors. We previously standardized a derivative of bovine colostrum (SBCD), deprived of casein and fat and rich in cytokines. In the present study, we tested its possible use as an adjuvant in bone healing. SBCD contained factors involved in stromal cell stimulation and differentiation and induced cytokine production from stimulated mesenchymal stem cells (MSCs). In vitro, SBCD promoted proliferation, migration and, in association with osteogenic factors, osteogenic differentiation of osteoblastic and MSCs. In in vivo experiments of subcutaneous Matrigel injection in mice, SBCD plus hydroxyapatite, but not hydroxyapatite nor SBCD alone, induced recruitment of macrophages and stromal cells. After 60 days, plugs containing SBCD and hydroxyapatite were densely calcified and diffusely positive for osteocalcin, supporting the occurrence of an early osteogenic process. These results indicate that SBCD is a rich source of factors with osteoinductive properties. Graphical Abstract Induction of osteogenic differentiation by a standardized a derivative of bovine colostrum was tested in vitro and in vivo.

Effect of the monoclonal antibody TRC105 in combination with Sunitinib on renal tumor derived endothelial cells

Anti-angiogenic therapy is an important strategy to limit growth, development and expansion of solid tumors. However, resistance to VEGF-targeting agents may develop, due to activation of alternative pro-angiogenic pathways, indicating the need of multiple target strategy. Here we obtained tumor endothelial cells (TEC) either from total renal carcinomas or from renal cancer stem cells (CSC-TEC) and we tested the effect of a CD105 targeting monoclonal antibody, TRC105, alone or in association with anti-VEGF drugs. We demonstrated that TRC105 impaired the ability of TEC and CSC-TEC to organize in tubular structures, whereas it did not limit proliferation or survival. The combination of TRC105 with different anti-angiogenic drugs showed a synergistic effect of TRC105 only in combination with the tyrosine kinase inhibitor Sunitinib. In particular, TRC105 plus Sunitinib reduced tubulogenesis, proliferation and survival of CSC-TEC and tumor-derived TEC in a similar manner. At a molecular level, we showed that the combination of TRC105 and Sunitinib induced the phosphorylation of Smad 2/3 to promote endothelial cell death. Moreover, TRC105 enhanced the inhibitory effect of Sunitinib on VEGF signaling and reduced VEGFR2-Akt-Creb activation, suggesting a molecular cooperation between the two drugs. Our results highlight that the combined inhibition of VEGF and TGF-β pathway may have a potential use in renal cell carcinoma therapy.

Extracellular vesicles from human liver stem cells inhibit tumor angiogenesis: HLSC extracellular vesicles inhibit tumor angiogenesis

Human liver stem‐like cells (HLSC) and derived extracellular vesicles (EVs) were previously shown to exhibit anti‐tumor activity. In our study, we investigated whether HLSC‐derived EVs (HLSC‐EVs) were able to inhibit tumor angiogenesis in vitro and in vivo, in comparison with EVs derived from mesenchymal stem cells (MSC‐EVs). The results obtained indicated that HLSC‐EVs, but not MSC‐EVs, inhibited the angiogenic properties of tumor‐derived endothelial cells (TEC) both in vitro and in vivo in a model of subcutaneous implantation in Matrigel. Treatment of TEC with HLSC‐EVs led to the down‐regulation of pro‐angiogenic genes. Since HLSC‐EVs carry a specific set of microRNAs (miRNAs) that could target these genes, we investigated their potential role by transfecting TEC with HLSC‐EV specific miRNAs. We observed that four miRNAs, namely miR‐15a, miR‐181b, miR‐320c and miR‐874, significantly inhibited the angiogenic properties of TEC in vitro, and decreased the expression of some predicted target genes (ITGB3, FGF1, EPHB4 and PLAU). In parallel, TEC treated with HLSC‐EVs significantly enhanced expression of miR‐15a, miR‐181b, miR‐320c and miR‐874 associated with the down‐regulation of FGF1 and PLAU. In summary, HLSC‐EVs possess an anti‐tumorigenic effect, based on their ability to inhibit tumor angiogenesis.