Uveal melanoma (UM) is the most common intraocular tumor in adults. Nearly half of UM patients develop metastatic disease and often succumb within months because effective therapy is lacking. A novel therapeutic approach has been suggested by the discovery that UM cell lines driven by mutant constitutively active Gq or G11 can be targeted by FR900359 (FR) or YM-254890, which are bioavailable, selective inhibitors of the Gq/11/14 subfamily of heterotrimeric G proteins. Here, we have addressed the therapeutic potential of FR for UM. We found that FR inhibited all oncogenic Gq/11 mutants reported in UM. FR arrested growth of all Gq/11-driven UM cell lines tested, but induced apoptosis only in a few. Similarly, FR inhibited growth of, but did not efficiently kill, UM tumor cells from biopsies of primary or metastatic tumors. FR evoked melanocytic redifferentiation of UM tumor cells with low (class 1), but not high (class 2), metastatic potential. FR administered systemically below its LD 50 strongly inhibited growth of PDX-derived class 1 and class 2 UM tumors in mouse xenograft models and reduced blood pressure transiently. FR did not regress xenografted UM tumors or significantly affect heart rate, liver function, hematopoiesis, or behavior. These results indicated the existence of a therapeutic window in which FR can be explored for treating UM and potentially other diseases caused by constitutively active Gq/11.

No abstract

No abstract

Gradual loss of functional elastin fibers during aging leads to increased arterial stiffening and decreased compliance. Elastin insufficiency in mice and humans has been shown to be associated with arteriopathy and the development of hypertension. However, it is unclear whether elastin insufficiency in the resistance vasculature, as occurs in the renal vascular bed, contributes to age‐related decline in renal function. We hypothesized that elastin insufficiency exacerbates age‐related impairment of renal hemodynamics by accelerating functional and structural changes of the renal microvasculature. We assessed renal hemodynamics in anesthetized young (4‐6‐month‐old) and old (14–16‐month‐old) female wild‐type (WT) and elastin heterozygous (Eln+/‐) mice. Renal autoregulation was assessed by a stepwise increase in renal perfusion pressure (RPP) by simultaneously occluding the superior mesenteric and celiac arteries. Autonomic activity was clamped by continuous infusion of a cocktail containing vasoactive hormones. Baseline systolic blood pressure (SBP; 91.1±4.2 vs 90.1±3.1mmHg) and renal vascular resistance (RVR; 13.1±2.4 vs 10.0±1.5 mmHg/μL/min/g left kidney weight) were elevated in old versus young WT mice. Renal blood flow (RBF; 7.3±1.7 vs 9.8±1.4 μL/min/g left kidney weight), renal plasma flow (RPF; 5±1.2 vs 6±1mL/min/g left kidney weight) and glomerular filtration rate (GFR), all trended lower in old WT mice compared to young WT mice. However, in Eln+/‐mice, SBP was lower in old mice (78.2±9.4 vs 104.6±4.9mmHg), while RVR (13.5± 2.6 vs 14.4±1.1), RBF (6.7±1.2 vs 7.5±0.6), RPF (4.2±0.7 vs 4.5±0.3) and GFR were all similar between young and old mice. Increasing RPP caused a robust RVR and RPF response in young vs old WT mice. In contrast, the maximal changes in RBF (5.8±0.6 vs 5.5±1 μL/min/g left kidney weight), RVR (23.8±2.5 vs 21.8±7.0 mmHg/μL/min/g left kidney weight) were less robust and similar between young and old Eln+/‐mice. Autoregulatory index average values were closer to 0 in young and old Eln+/‐and old WT miceindicating greater impairment of renal autoregulation compared to young WT mice. Correlation analysis between pulse pressure and RBF showed that a high pulse pressure was more positively correlated to high RBF in young and old Eln+/‐mice as well as old WT mice. Together, our data demonstrate that elastin insufficiency accelerates age‐related impairment of renal hemodynamics and autoregulation likely mediated by functional and structural remodeling of the renal microvasculature.

Age-related decline in functional elastin is associated with increased arterial stiffness, a known risk factor for developing cardiovascular disease. While the contribution of elastin insufficiency to the stiffening of conduit arteries is well described, little is known about the impact on the structure and function of the resistance vasculature, which contributes to total peripheral resistance and the regulation of organ perfusion. In this study, we determined how elastin insufficiency impinges on age-related changes in the structure and biomechanical properties of the renal microvasculature, altering renal hemodynamics and the response of the renal vascular bed to changes in renal perfusion pressure (RPP) in female mice. Using Doppler ultrasonography, we found that resistive index and pulsatility index were elevated in young Eln+/− and aged mice. Histological examination showed thinner internal and external elastic laminae, accompanied by increased elastin fragmentation in the medial layer without any calcium deposits in the small intrarenal arteries of kidneys from young Eln+/− and aged mice. Pressure myography of interlobar arteries showed that vessels from young Eln+/− and aged mice had a slight decrease in distensibility during pressure loading but a substantial decline in vascular recoil efficiency upon pressure unloading. To examine whether structural changes in the renal microvasculature influenced renal hemodynamics, we clamped neurohumoral input and increased renal perfusion pressure by simultaneously occluding the superior mesenteric and celiac arteries. Increased renal perfusion pressure caused robust changes in blood pressure in all groups; however, changes in renal vascular resistance and renal blood flow (RBF) were blunted in young Eln+/− and aged mice, accompanied by decreased autoregulatory index, indicating greater impairment of renal autoregulation. Finally, increased pulse pressure in aged Eln+/− mice positively correlated with high renal blood flow. Together, our data show that the loss of elastin negatively affects the structural and functional integrity of the renal microvasculature, ultimately worsening age-related decline in kidney function.