Role of PKCepsilon in PGF2alpha-stimulated MMP-2 secretion from human ciliary muscle cells

FP and EP2 prostanoid receptor agonist drugs and aqueous humor outflow devices for treating ocular hypertension and glaucoma

Prostaglandin (PG) receptors represent important druggable targets due to the many diverse actions of PGs in the body. From an ocular perspective, the discovery, development, and health agency approvals of prostaglandin F (FP) receptor agonists (FPAs) have revolutionized the medical treatment of ocular hypertension (OHT) and glaucoma. FPAs, such as latanoprost, travoprost, bimatoprost, and tafluprost, powerfully lower and control intraocular pressure (IOP), and became first-line therapeutics to treat this leading cause of blindness in the late 1990s to early 2000s. More recently, a latanoprost-nitric oxide (NO) donor conjugate, latanoprostene bunod, and a novel FP/EP3 receptor dual agonist, sepetaprost (ONO-9054 or DE-126), have also demonstrated robust IOP-reducing activity. Moreover, a selective non-PG prostanoid EP2 receptor agonist, omidenepag isopropyl (OMDI), was discovered, characterized, and has been approved in the United States, Japan and several other Asian countries for treating OHT/glaucoma. FPAs primarily enhance uveoscleral (UVSC) outflow of aqueous humor (AQH) to reduce IOP, but cause darkening of the iris and periorbital skin, uneven thickening and elongation of eyelashes, and deepening of the upper eyelid sulcus during chronic treatment. In contrast, OMDI lowers and controls IOP by activation of both the UVSC and trabecular meshwork outflow pathways, and it has a lower propensity to induce the aforementioned FPA-induced ocular side effects. Another means to address OHT is to physically promote the drainage of the AQH from the anterior chamber of the eye of patients with OHT/glaucoma. This has successfully been achieved by the recent approval and introduction of miniature devices into the anterior chamber by minimally invasive glaucoma surgeries. This review covers the three major aspects mentioned above to highlight the etiology of OHT/glaucoma, and the pharmacotherapeutics and devices that can be used to combat this blinding ocular disease.

The roles of prostaglandin F2 in regulating the expression of matrix metalloproteinase-12 via an insulin growth factor-2-dependent mechanism in sheared chondrocytes

Osteoarthritis (OA) was recently identified as being regulated by the induction of cyclooxygenase-2 (COX-2) in response to high fluid shear stress. Although the metabolic products of COX-2, including prostaglandin (PG)E₂, 15-deoxy-Δ^12,14-PGJ₂ (15d-PGJ₂), and PGF_2α, have been reported to be effective in regulating the occurrence and development of OA by activating matrix metalloproteinases (MMPs), the roles of PGF_2α in OA are largely overlooked. Thus, we showed that high fluid shear stress induced the mRNA expression of MMP-12 via cyclic (c)AMP- and PGF_2α-dependent signaling pathways. Specifically, we found that high fluid shear stress (20 dyn/cm²) significantly increased the expression of MMP-12 at 6 h ( > fivefold), which then slightly decreased until 48 h ( > threefold). In addition, shear stress enhanced the rapid synthesis of PGE₂ and PGF_2α, which generated synergistic effects on the expression of MMP-12 via EP2/EP3-, PGF2α receptor (FPR)-, cAMP- and insulin growth factor-2 (IGF-2)-dependent phosphatidylinositide 3-kinase (PI3-K)/protein kinase B (AKT), c-Jun N-terminal kinase (JNK)/c-Jun, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB)-activating pathways. Prolonged shear stress induced the synthesis of 15d-PGJ₂, which is responsible for suppressing the high levels of MMP-12 at 48 h. These in vitro observations were further validated by in vivo experiments to evaluate the mechanisms of MMP-12 upregulation during the onset of OA by high fluid shear stress. By delineating this signaling pathway, our data provide a targeted therapeutic basis for combating OA.

Shear stress induces cartilage cells to produce hormone-like molecules that activate the expression of an enzyme implicated in the development of osteoarthritis, a degenerative joint disease. Pu Wang and colleagues from Northeastern University in Shenyang, China, exposed human cartilage cells to high fluid shear stress for up to 2 days. This frictional strain rapidly stimulated the production of a proinflammatory enzyme, COX-2, which in turn promoted the synthesis of two hormone-like substances, called prostaglandins. These prostaglandins, PGE₂ and PGF_2α, then induced expression of an osteoarthritis-associated enzyme called MMP-12 that destroys the supporting structure that surrounds cartilage cells. The researchers, working both in human cells and in mouse models, further delineated several intermediate signaling molecules in the pathway linking shear stress with MMP-12 activation, thereby revealing several new potential drug targets for combating osteoarthritis in patients.

Endothelial dysfunction and oxidative stress in polycystic kidney disease

Cardiovascular disease (CVD) is the leading cause of premature mortality in ADPKD patients. The aim was to identify potential serum biomarkers associated with the severity of ADPKD. Serum samples from a homogenous group of 61 HALT study A ADPKD patients [early disease group with estimated glomerular filtration rate (eGFR) >60 ml·min(-1)·1.73 m(-2)] were compared with samples from 49 patients from the HALT study B group with moderately advanced disease (eGFR 25-60 ml·min(-1)·1.73 m(-2)). Targeted tandem-mass spectrometry analysis of markers of endothelial dysfunction and oxidative stress was performed and correlated with eGFR and total kidney volume normalized to the body surface area (TKV/BSA). ADPKD patients with eGFR >60 ml·min(-1)·1.73 m(-2) showed higher levels of CVD risk markers asymmetric and symmetric dimethylarginine (ADMA and SDMA), homocysteine, and S-adenosylhomocysteine (SAH) compared with the healthy controls. Upon adjustments for age, sex, systolic blood pressure, and creatinine, SDMA, homocysteine, and SAH remained negatively correlated with eGFR. Resulting cellular methylation power [S-adenosylmethionine (SAM)/SAH ratio] correlated with the reduction of renal function and increase in TKV. Concentrations of prostaglandins (PGs), including oxidative stress marker 8-isoprostane, as well as PGF2α, PGD₂, and PGE₂, were markedly elevated in patients with ADPKD compared with healthy controls. Upon adjustments for age, sex, systolic blood pressure, and creatinine, increased PGD₂ and PGF₂α were associated with reduced eGFR, whereas 8-isoprostane and again PGF₂α were associated with an increase in TKV/BSA. Endothelial dysfunction and oxidative stress are evident early in ADPKD patients, even in those with preserved kidney function. The identified pathways may provide potential therapeutic targets for slowing down the disease progression.

Heparin binding VEGF isoforms attenuate hyperoxic embryonic lung growth retardation via a FLK1-neuropilin-1-PKC dependent pathway

Background

Previous work in our laboratory demonstrated that hyperoxia suppressed the expression of vascular endothelial growth factor (VEGF) by the embryonic lung, leading to increased epithelial cell apoptosis and failure of explant airway growth and branching that was rescued by the addition of Vegf165. The aims of this study were to determine protective pathways by which VEGF isoforms attenuate hyperoxic lung growth retardation and to identify the target cell for VEGF action.

Methods

Timed pregnant CD-1 or fetal liver kinase (FLK1)-eGFP lung explants cultured in 3% or 50% oxygen were treated ± Vegf121, VEGF164/Vegf165 or VEGF188 in the presence or absence of anti-rat neuropilin-1 (NRP1) antibody or GO6983 (protein kinase C (PKC) pan-inhibitor) and lung growth and branching quantified. Immunofluorescence studies were performed to determine apoptosis index and location of FLK1 phosphorylation and western blot studies of lung explants were performed to define the signaling pathways that mediate the protective effects of VEGF.

Results

Heparin-binding VEGF isoforms (VEGF164/Vegf165 and VEGF188) but not Vegf121 selectively reduced epithelial apoptosis and partially rescued lung bud branching and growth. These protective effects required NRP1-dependent FLK1 activation in endothelial cells. Analysis of downstream signaling pathways demonstrated that the VEGF-mediated anti-apoptotic effects were dependent on PKC activation.

Conclusions

Vegf165 activates FLK1-NRP1 signaling in endothelial cells, leading to a PKC-dependent paracrine signal that in turn inhibits epithelial cell apoptosis.

A review on the role of L-carnitine in the management of tamoxifen side effects in treated women with breast cancer

L-carnitine is an antioxidant and is found to be a protective agent against many diseases including cancer. This review illustrates the possible role of L-carnitine as an add-on therapy to breast cancer patients maintained on tamoxifen. The objectives of carnitine treatment are diverse: improving tamoxifen-related side effects, offering better cancer prognosis by reducing the risk of developing cancer recurrence or metastasis, and modulating the growth factors which may be, in part, a prospective illustration to overcome tamoxifen resistance. So, it could be recommended to supplement L-carnitine to breast cancer patients starting tamoxifen treatment.

The activation of matrix metalloproteinase-2 induced by protein kinase C alpha in decidualization

This study investigated the protein kinase C (PKC) and matrix metalloproteinase-2 (MMP-2) in the development of deciduomata in pseudo-pregnant and pregnant rats. The results showed that the expression of MMP-2 was significantly increased from day 2 to day 5 in pseudo-pregnancy and from day 7 to day 9 in pregnancy. To further investigate the correlation between MMP-2 and protein kinase C alpha (PKC alpha), the expression of MMP-2 in the 12-O-tetradecanoylphorbol 13-acetate (TPA)-treated organotypic culture of decidual tissue was determined. The results showed that the active form of MMP-2 was significantly increased in the TPA-treated cultures. Moreover, this response was inhibited by the PKC inhibitor H7, the PKC alpha specific inhibitor Gö-6976 and the translation inhibitor cycloheximide, but not by the transcription inhibitor actinomycin D or the replication inhibitor mitomycin C. In addition, TPA also reversed the MMP-2 expression after by progesterone pretreatment in the primary decidual cells. These findings indicate that PKC alpha may play an important role in the regulation of the MMP-2 expression during decidualization.