Arthur Polans

Cells. 2022 Mar 11;11(6):969. doi: 10.3390/cells11060969.

ABSTRACT

Neovascular or wet age-related macular degeneration (nAMD) causes vision loss due to inflammatory and vascular endothelial growth factor (VEGF)-driven neovascularization processes in the choroid. Due to the excess in VEGF levels associated with nAMD, anti-VEGF therapies are utilized for treatment. Unfortunately, not all patients have a sufficient response to such therapies, leaving few if any other treatment options for these patients. Sphingosine-1-phosphate (S1P) is a bioactive lipid mediator found in endothelial cells that participates in modulating barrier function, angiogenesis, and inflammation. S1P, through its receptor (S1PR1) in endothelial cells, prevents illegitimate sprouting angiogenesis during vascular development. In the present paper, we show that, in choroidal endothelial cells, S1PR1 is the most abundantly expressed S1P receptor and agonism of S1PR1-prevented choroidal endothelial cell capillary morphogenesis in culture. Given that nAMD pathogenesis draws from enhanced inflammation and angiogenesis as well as a loss of barrier function, we assessed the impact of S1PR agonism on choroidal neovascularization in vivo. Using laser photocoagulation rupture of Bruch's membrane to induce choroidal neovascularization, we show that S1PR non-selective (FTY720) and S1PR1 selective (CYM5442) agonists significantly inhibit choroidal neovascularization in this model. Thus, utilizing S1PR agonists to temper choroidal neovascularization presents an additional novel use for these agonists presently in clinical use for multiple sclerosis as well as other inflammatory diseases.

PMID:35326420 | PMC:PMC8946992 | DOI:10.3390/cells11060969

J Ocul Pharmacol Ther. 2021 Dec;37(10):545-555. doi: 10.1089/jop.2021.0015. Epub 2021 Sep 28.

ABSTRACT

Purpose: Instability of the tear film leads to evaporative dry eye disease (EDED), but the Harderian gland in some terrestrial vertebrates may produce novel lipids that stabilize the tear film and protect against dry eye. Here, the nonpolar lipids in the Harderian gland and tears of the rabbit but absent in human tears were identified and tested in preclinical studies to determine whether they could treat severe EDED. Methods: Lipids were identified primarily by atmospheric pressure chemical ionization mass spectrometry (MS) and fragmentation MS/MS. An identified lipid was synthesized and formulated as an emulsion and as a cyclodextrin (CD) clathrate. Following doses with test agents and controls, tear film breakup time (TBUT), tear production, corneal fluorescein staining, macrophage infiltration, and goblet cell survival were measured using standard tests at 0, 2 and 4 weeks in an animal model of EDED. Results: The lipid emulsion increased TBUT (P < 0.01) and tear production (P < 0.05), while it decreased corneal staining (P < 0.01) compared to controls. The lipid CD formulation increased TBUT (P < 0.05) and tear production (P < 0.05) but had no significant effect on the remaining test parameters. There were no differences in macrophage infiltration and conjunctival impression cytology scores between the formulations and their vehicle controls. Conclusions: Lipids in the rabbit Harderian gland and tears differ from those identified in human meibum and tears. These unique rabbit lipids may confer a protective effect against EDED and, as supplements to human tears, fulfill a similar role.

PMID:34590914 | PMC:PMC8713569 | DOI:10.1089/jop.2021.0015

Ocul Oncol Pathol. 2017 Dec;4(1):52-56. doi: 10.1159/000475994. Epub 2017 Jul 19.

ABSTRACT

BACKGROUND/AIMS: Establish a reliable rabbit dry eye (DE) model.

METHODS: An interventional cohort study surgically removing glands contributing to the tear film. Eight rabbits were studied after removal of left lacrimal, Harderian, or both glands. Additional rabbits had Meibomian glands in the left eye thermally obstructed. All were followed for 10 weeks with phenol red thread (PRT) and slit-lamp examination with 2% fluorescein. We assessed corneal sensitivity using a Cochet-Bonnet esthesiometer. Outcome measures were severity/duration of reduced PRT, punctate epithelial erosions (PEE), and histologic evidence of corneal pannus.

RESULTS: Fluorescein staining demonstrated signs of dryness including PEE in all of the interventional eyes. The subjective measurement of epithelial erosions correlated with decreased tear production. PRT measurements in the control eyes averaged 31.54 mm (±1.83) and 22.71 mm (±1.60) in the eight left eyes, without loss of corneal sensitivity.

CONCLUSIONS: Surgical removal of either the Harderian or lacrimal gland results in statistically significant decreases in tear volume and the development of severe DE. Removal of both glands results in the occurrence of a DE of comparable severity/duration to removal of either the lacrimal or Harderian gland alone. Meibomian gland obstruction contributes less to the DE model.

PMID:29344500 | PMC:PMC5757560 | DOI:10.1159/000475994

J Neurosurg. 2017 May;126(5):1448-1460. doi: 10.3171/2016.1.JNS152077. Epub 2016 Jul 15.

ABSTRACT

OBJECTIVE Glioblastoma multiforme (GBM) is an aggressive brain cancer with median survival of less than 2 years with current treatment. Glioblastomas exhibit extensive intratumoral and interpatient heterogeneity, suggesting that successful therapies should produce broad anticancer activities. Therefore, the natural nontoxic pleiotropic agent, resveratrol, was studied for antitumorigenic effects against GBM. METHODS Resveratrol's effects on cell proliferation, sphere-forming ability, and invasion were tested using multiple patient-derived GBM stem-like cell (GSC) lines and established U87 glioma cells, and changes in oncogenic AKT and tumor suppressive p53 were analyzed. Resveratrol was also tested in vivo against U87 glioma flank xenografts in mice by using multiple delivery methods, including direct tumor injection. Finally, resveratrol was delivered directly to brain tissue to determine toxicity and achievable drug concentrations in the brain parenchyma. RESULTS Resveratrol significantly inhibited proliferation in U87 glioma and multiple patient-derived GSC lines, demonstrating similar inhibitory concentrations across these phenotypically heterogeneous lines. Resveratrol also inhibited the sphere-forming ability suggesting anti-stem cell effects. Additionally, resveratrol blocked U87 glioma and GSC invasion in an in vitro Matrigel Transwell assay at doses similar to those mediating antiproliferative effects. In U87 glioma cells and GSCs, resveratrol reduced AKT phosphorylation and induced p53 expression and activation that led to transcription of downstream p53 target genes. Resveratrol administration via oral gavage or ad libitum in the water supply significantly suppressed GBM xenograft growth; intratumoral or peritumoral resveratrol injection further suppressed growth and approximated tumor regression. Intracranial resveratrol injection resulted in 100-fold higher local drug concentration compared with intravenous delivery, and with no apparent toxicity. CONCLUSIONS Resveratrol potently inhibited GBM and GSC growth and infiltration, acting partially via AKT deactivation and p53 induction, and suppressed glioblastoma growth in vivo. The ability of resveratrol to modulate AKT and p53, as well as reportedly many other antitumorigenic pathways, is attractive for therapy against a genetically heterogeneous tumor such as GBM. Although resveratrol exhibits low bioavailability when administered orally or intravenously, novel delivery methods such as direct injection (i.e., convection-enhanced delivery) could potentially be used to achieve and maintain therapeutic doses in the brain. Resveratrol's nontoxic nature and broad anti-GBM effects make it a compelling candidate to supplement current GBM therapies.

PMID:27419830 | PMC:PMC5237623 | DOI:10.3171/2016.1.JNS152077

Toxicol Appl Pharmacol. 2015 Nov 1;288(3):453-62. doi: 10.1016/j.taap.2015.08.016. Epub 2015 Sep 1.

ABSTRACT

Paclitaxel, etoposide, vincristine and doxorubicin are examples of natural products being used as chemotherapeutics but with adverse side effects that limit their therapeutic window. Natural products derived from plants and having low toxicity, such as quercetin, resveratrol, epigallocatechin gallate and piceatannol, have been shown to inhibit tumor cell growth both in vitro and in pre-clinical models of cancer, but their mechanisms of action have not been fully elucidated, thus restricting their use as prototypes for developing synthetic analogs with improved anti-cancer properties. We and others have demonstrated that one of the earliest and consistent events upon exposure of tumor cells to these less toxic natural products is a rise in cytoplasmic calcium, activating several pro-apoptotic pathways. We describe here a G protein/inositol 1,4,5-trisphosphate pathway (InsP3) in MDA-MB-231 human breast cancer cells that mediates between these less toxic natural products and the release of calcium from the endoplasmic reticulum. Further, we demonstrate that this elevation of intracellular calcium modulates p53 activity and the subsequent transcription of several pro-apoptotic genes encoding PIG8, CD95, PIDD, TP53INP, RRM2B, Noxa, p21 and PUMA. We conclude from our findings that less toxic natural products likely bind to a G protein coupled receptor that activates a G protein-mediated and calcium-dependent pathway resulting selectively in tumor cell death.

PMID:26341291 | PMC:PMC4620942 | DOI:10.1016/j.taap.2015.08.016

Molecules. 2014 Oct 30;19(11):17578-603. doi: 10.3390/molecules191117578.

ABSTRACT

The objective of this study was to determine whether resveratrol or a defined, reconstituted grape powder can attenuate the formation of new blood vessels in a mouse model of choroidal neovascularization (CNV). To accomplish this objective, C57BL/6J mice were randomized into control or treatment groups which received either resveratrol or grape powder by daily oral gavage, resveratrol or grape powder delivered ad libitum through the drinking water, or resveratrol by slow release via implanted osmotic pumps. A laser was used to rupture Bruch's membrane to induce CNV which was then detected in sclerochoroidal eyecups stained with antibodies against intercellular adhesion molecule-2. CNV area was measured using fluorescence microscopy and Image J software. Ad libitum delivery of both resveratrol and grape powder was shown to significantly reduce the extent of CNV by 68% and 57%, respectively. Parallel experiments conducted in vitro demonstrated that resveratrol activates p53 and inactivates Akt/protein kinase B in choroidal endothelial cells, contributing to its anti-proliferative and anti-migratory properties. In addition resveratrol was shown to inhibit the formation of endothelial cell networks, augmenting its overall anti-angiogenic effects. The non-toxic nature of resveratrol makes it an especially attractive candidate for the prevention and/or treatment of CNV.

PMID:25361423 | PMC:PMC4313391 | DOI:10.3390/molecules191117578

Invest Ophthalmol Vis Sci. 2014 Oct 22;55(10):6649-50. doi: 10.1167/iovs.14-14843.

NO ABSTRACT

PMID:25338685 | DOI:10.1167/iovs.14-14843

PLoS One. 2013;8(3):e59156. doi: 10.1371/journal.pone.0059156. Epub 2013 Mar 19.

ABSTRACT

For many cancers, the lack of potency and the toxicity of current drugs limits the dose achievable in patients and the efficacy of treatment. Among them, retinoblastoma is a rare cancer of the eye for which better chemotherapeutic options are needed. Combination therapy is a compelling approach to enhance the efficacy of current treatment, however clinical trials to test rationally designed combinations of approved drugs are slow and expensive, and limited by our lack of in-depth knowledge of drug specificity. Since many patients already turn to nutraceuticals in hopes of improving their condition, we hypothesized that certain approved drugs could potentially synergize with widely consumed supplements. Following this hypothesis, we devised an alternative screening strategy aimed at taking advantage of a bait compound such as a nutraceutical with potential therapeutic benefits but low potency, by screening chemical libraries for approved drugs that synergize with this companion effector. As a proof of concept, we sought to identify approved drugs with synergetic therapeutic effects toward retinoblastoma cells in combination with the antioxidant resveratrol, popular as a supplement. We systematically tested FDA-approved drugs and known bioactives seeking to identify such pairs, which led to uncovering only a few additive combinations; but to our surprise, we identified a class of anticancer drugs widely used in the clinic whose therapeutic effect is antagonized with resveratrol. Our observations could explain in part why some patients do not respond well to treatment. Our results validate this alternative approach, and we expect that our companion effector strategy could significantly impact both drug discovery and the nutraceutical industry.

PMID:23527118 | PMC:PMC3602587 | DOI:10.1371/journal.pone.0059156

Int Immunopharmacol. 2011 Nov;11(11):1877-86. doi: 10.1016/j.intimp.2011.07.019. Epub 2011 Aug 18.

ABSTRACT

We evaluated the anti-tumor effect of Resveratrol (RV) on M21 and NXS2 tumor cell lines and its immunosuppressive activity on human and murine immune cells to determine the potential for combining RV and immunotherapy. In vitro, concentrations of RV≥25 mcM, inhibited cell proliferation, blocked DNA synthesis and induced G1 phase arrest in tumor and immune cells. RV at 12-50 mcM inhibited antibody dependent cell mediated cytotoxicity (ADCC) of tumor cells facilitated by the hu14.18-IL2 immunocytokine (IC). The in vivo anti-tumor and immunomodulating activity of RV given systemically were assessed in mice. Results showed that this RV regimen inhibited the growth of NXS2 tumors in vivo but did not appear to interfere with blood cell count, splenocyte or macrophage function. Thus, RV may be a candidate for combining with immunotherapy.

PMID:21854876 | PMC:PMC3204008 | DOI:10.1016/j.intimp.2011.07.019

Melanoma Res. 2011 Jun;21(3):180-7. doi: 10.1097/CMR.0b013e3283456dfc.

ABSTRACT

Resveratrol, a nontoxic natural product, exhibits multifaceted biological effects including antimutagenic and anticancer properties. We examined the effect of resveratrol on the expression and activation of Akt/protein kinase B and its impact on melanoma cell migration and invasiveness. We also explored the use of resveratrol as an antimalignant treatment option against skin melanoma in mouse models of the disease. Akt expression and activity were determined by a combination of real-time PCR and western blot analysis. Cell lines stably expressing Akt or a dominant negative variant were used to further establish the role of Akt during the response to resveratrol. Wound healing and transwell assays were used as in-vitro correlates of melanoma cell migration and invasiveness. The efficacy of resveratrol in the treatment of melanoma was assessed in two syngeneic mouse models. Resveratrol downregulated and inactivated Akt in B16F10 and B16BL6 melanoma cells. Resveratrol also inhibited the migratory and invasive properties of these highly malignant cells. The reduction of cell migration and invasion, however, was reversed in cell lines overexpressing Akt or after cotreatment with pharmacological inhibitors that blocked Akt degradation. Dominant-negative Akt cells were more sensitive to resveratrol and had diminished migratory properties. Oral treatment with resveratrol reduced primary tumor volume, Akt expression, and the propensity for metastasis in syngeneic mouse models of melanoma. These results suggest that resveratrol can reduce the malignant properties of highly invasive melanoma cells by inactivating Akt. The nontoxic targeting of Akt by resveratrol makes it an attractive treatment option for melanoma.

PMID:21407133 | PMC:PMC3086957 | DOI:10.1097/CMR.0b013e3283456dfc

J Agric Food Chem. 2011 May 11;59(9):4979-86. doi: 10.1021/jf104901g. Epub 2011 Apr 12.

ABSTRACT

Resveratrol, a nontoxic polyphenol, has been shown to inhibit tumor growth in a xenograft mouse model of neuroblasoma. However, resveratrol is rapidly metabolized, mainly to its glucuronidated and sulfated derivatives. This study demonstrates that resveratrol alone, and not the glucuronidated or sulfated metabolites, is taken up into tumor cells, induces a rise in [Ca(2+)](i), and ultimately leads to a decrease in tumor cell viability. A new water-soluble resveratrol formulation was delivered directly at the site of the tumor in a neuroblastoma mouse model. The amount of unmodified resveratrol associated with the tumor increased more than 1000-fold. The increase of unmodified resveratrol associated with the tumor resulted in tumor regression. The number of residual tumor cells that remained viable also decreased as the ratio of the metabolites relative to unmodified resveratrol declined.

PMID:21401048 | PMC:PMC3099401 | DOI:10.1021/jf104901g

Cancer Immunol Immunother. 2011 May;60(5):731-8. doi: 10.1007/s00262-011-0971-0. Epub 2011 Feb 22.

ABSTRACT

We investigated the anti-tumor effect of peritumoral resveratrol in combination with immunotherapy in vivo in neuroblastoma-bearing mice. Subcutaneous NXS2 tumors were induced in A/J mice. On day 10, some mice received 15 mcg of intravenous immunocytokine for 5 days, mice received 20 mg of peritumoral resveratrol twice a week (starting on day 12) for a total of 5 injections, and a separate group received a combination of both regimens. Tumor progression and survival were assessed every 3-4 days. Blood and primary tumor tissue samples were collected on day 20 for Complete Blood Count and CD45 immunohistochemistry and histology, respectively. The primary tumor regressed in all mice receiving peritumoral resveratrol. Most of these mice receiving peritumoral resveratrol alone developed metastatic tumors and recurrence of the primary tumor after cessation of therapy. When resveratrol and immunocytokine regimens were combined, 61% of the mice receiving this combination therapy resolved their primary tumors and survived without developing metastatic tumors, compared to 15 and 13% receiving resveratrol or immunocytokine alone, respectively. None of the therapeutic regimes prevented lymphocyte infiltration or affected the complete blood count. Greater necrosis was observed microscopically in tumors from mice receiving the combination therapy. These results demonstrate that the combination therapy of peritumoral resveratrol plus intravenous immunocytokine provides better anti-tumor effects in this model than either therapy alone.

PMID:21340652 | PMC:PMC3094716 | DOI:10.1007/s00262-011-0971-0

Clin Cancer Res. 2010 Dec 15;16(24):5942-8. doi: 10.1158/1078-0432.CCR-10-1486. Epub 2010 Nov 2.

ABSTRACT

Low cancer survival rates and the serious side effects often associated with current chemotherapeutics highlight the need for new and effective nontoxic anticancer agents. Since 1997 when Jang and colleagues first described resveratrol's ability to inhibit carcinogenesis, it has consistently proven effective at tumor inhibition in diverse human cancer models. This finding has raised the hope that resveratrol would pioneer a novel class of nontoxic chemotherapeutics. As a consequence of initial basic and preclinical studies, resveratrol is now being extensively promoted in the unregulated nutraceutical sector. However, some fundamental aspects of resveratrol's action need to be understood before it can be developed into a clinically viable anticancer drug. These areas pertain to the key mechanism(s) by which resveratrol potentiates its antitumor effects. Current research suggests that these mechanisms might be through novel pathways, requiring an understanding of cellular uptake, sentinel targets, and in vivo biological networks. The metabolism of resveratrol and its bioavailability also warrant further consideration in light of recent in vitro and in vivo studies. Finally, we need to appreciate the sorts of information about resveratrol that may translate between different disease entities. We present a critical discussion of these issues and suggest important experiments that could pave the way to the successful translation of resveratrol to the clinic.

PMID:21045084 | PMC:PMC3057445 | DOI:10.1158/1078-0432.CCR-10-1486