Therapeutic targeting of oncogenic transcription factors by natural products in eye cancer

Signaling pathways driving ocular malignancies and their targeting by bioactive phytochemicals

Ocular cancers represent a rare pathology. The American Cancer Society estimates that 3,360 cases of ocular cancer occur annually in the United States. The major types of cancers of the eye include ocular melanoma (also known as uveal melanoma), ocular lymphoma, retinoblastoma, and squamous cell carcinoma. While uveal melanoma is one of the primary intraocular cancers with the highest occurrence in adults, retinoblastoma remains the most common primary intraocular cancer in children, and squamous cell carcinoma presents as the most common conjunctival cancer. The pathophysiology of these diseases involves specific cell signaling pathways. Oncogene mutations, tumor suppressor mutations, chromosome deletions/translocations and altered proteins are all described as causal events in developing ocular cancer. Without proper identification and treatment of these cancers, vision loss, cancer spread, and even death can occur. The current treatments for these cancers involve enucleation, radiation, excision, laser treatment, cryotherapy, immunotherapy, and chemotherapy. These treatments present a significant burden to the patient that includes a possible loss of vision and a myriad of side effects. Therefore, alternatives to traditional therapy are urgently needed. Intercepting the signaling pathways for these cancers with the use of naturally occurring phytochemicals could be a way to relieve both cancer burden and perhaps even prevent cancer occurrence. This research aims to present a comprehensive review of the signaling pathways involved in various ocular cancers, discuss current therapeutic options, and examine the potential of bioactive phytocompounds in the prevention and targeted treatment of ocular neoplasms. The current limitations, challenges, pitfalls, and future research directions are also discussed.

High-Throughput Screening of Natural Product and Synthetic Molecule Libraries for Antibacterial Drug Discovery

Due to the continued emergence of resistance and a lack of new and promising antibiotics, bacterial infection has become a major public threat. High-throughput screening (HTS) allows rapid screening of a large collection of molecules for bioactivity testing and holds promise in antibacterial drug discovery. More than 50% of the antibiotics that are currently available on the market are derived from natural products. However, with the easily discoverable antibiotics being found, finding new antibiotics from natural sources has seen limited success. Finding new natural sources for antibacterial activity testing has also proven to be challenging. In addition to exploring new sources of natural products and synthetic biology, omics technology helped to study the biosynthetic machinery of existing natural sources enabling the construction of unnatural synthesizers of bioactive molecules and the identification of molecular targets of antibacterial agents. On the other hand, newer and smarter strategies have been continuously pursued to screen synthetic molecule libraries for new antibiotics and new druggable targets. Biomimetic conditions are explored to mimic the real infection model to better study the ligand-target interaction to enable the designing of more effective antibacterial drugs. This narrative review describes various traditional and contemporaneous approaches of high-throughput screening of natural products and synthetic molecule libraries for antibacterial drug discovery. It further discusses critical factors for HTS assay design, makes a general recommendation, and discusses possible alternatives to traditional HTS of natural products and synthetic molecule libraries for antibacterial drug discovery.

The Role of Metalloproteinases and Their Tissue Inhibitors on Ocular Diseases: Focusing on Potential Mechanisms

Eye diseases are associated with visual impairment, reduced quality of life, and may even lead to vision loss. The efficacy of available treatment of eye diseases is not satisfactory. The unique environment of the eye related to anatomical and physiological barriers and constraints limits the bioavailability of existing agents. In turn, complex ethiopathogenesis of ocular disorders that used drugs generally are non-disease specific and do not act causally. Therefore, there is a need for the development of a new therapeutic and preventive approach. It seems that matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) have a significant role in the development and progression of eye diseases and could be used in the therapy of these disorders as pharmacological targets. MMPs and TIMPs play an important role in the angiogenesis, epithelial-mesenchymal transition, cell invasion, and migration, which occur in ocular diseases. In this review, we aim to describe the participation of MMPs and TIMPs in the eye diseases, such as age-related macular degeneration, cataract, diabetic retinopathy, dry eye syndrome, glaucoma, and ocular cancers, posterior capsule opacification focusing on potential mechanisms.

Creating and screening natural product libraries

Covering: up to 2020The National Cancer Institute of the United States (NCI) has initiated a Cancer Moonshot program entitled the NCI Program for Natural Product Discovery. As part of this effort, the NCI is producing a library of 1 000 000 partially purified natural product fractions which are being plated into 384-well plates and provided to the research community free of charge. As the first 326 000 of these fractions have now been made available, this review seeks to describe the general methods used to collect organisms, extract those organisms, and create a prefractionated library. Importantly, this review also details both cell-based and cell-free bioassay methods and the adaptations necessary to those methods to productively screen natural product libraries. Finally, this review briefly describes post-screen dereplication and compound purification and scale up procedures which can efficiently identify active compounds and produce sufficient quantities of natural products for further pre-clinical development.

A temperature-sensitive phase-change hydrogel of topotecan achieves a long-term sustained antitumor effect on retinoblastoma cells

Background

Retinoblastoma (Rb) is one of the most common malignancies among children. Following early diagnosis and prompt treatment, the clinical outcome or prognosis of Rb is promising. However, the prognosis or survival rates of patients with late-stage Rb remain poor. Current therapeutic strategies for advanced Rb mainly involve the use of advanced chemotherapeutic options. However, the efficacy of these strategies is not satisfactory. Therefore, the development of novel strategies to achieve a more effective antitumor effect on late-stage Rb is of crucial importance.

Methods and materials

Topotecan was dissolved in phosphate-buffered saline and prepared into a temperature-sensitive phase-change hydrogel (termed Topo-Gel). Moreover, Topo-Gel was injected into tumor tissues formed by Y79 cells (an Rb cell line) in nude mice to examine the long-term release and long-acting antitumor effect of Topo-Gel on Rb tumors.

Results

Topo-Gel transforms from liquid to a hydrogel at near body temperatures (phase-change temperature [T_1/2] was 37.23±0.473 °C), and maintains the slow release of topotecan in Rb tumor tissues. Following the subcutaneous injection of Topo-Gel, the treatment induced long-acting inhibition of tumor growth and relieved the adverse effects associated with topotecan. Topo-Gel, a temperature-sensitive phase-change hydrogel, is a slow-release system that prolongs the presence of topotecan in Rb tissues, and preserves the efficacy of topotecan in the long term.

Conclusion

Preparation of topotecan into a temperature-sensitive phase-change hydrogel achieves a long-term sustained antitumor effect on Rb cells, and may be a useful strategy for the treatment of intraocular Rb.

Citrus fruits intake and oral cancer risk: A systematic review and meta-analysis

OBJECTIVE

To quantify the relationship between Citrus intake and risk of cancer of the oral cavity and pharynx.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Ovid MEDLINE, EMBASE, and Web of Science were searched until September 2017. Search terms included Citrus, Citrus aurantifolia, Citrus sinensis, Citrus paradisi, Citrus fruits, Citrus fruits extract, Citrus oil, fruits, oral cancer, mouth cancer, mouth neoplasm.

STUDY SELECTION

The selection of studies and the systematic review were carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A pre-defined inclusion checklist resulted in the inclusion of articles which were (i) published in peer-reviewed scientific journals; (ii) English language; (iii) and included a measure of Citrus fruit intake and risk of oral and pharyngeal cancer. Studies were excluded if (i) preparations derived from other fruits were used, (ii) Citrus intake was combined with intake of other fruits; (iii) in vitro or animal models were used. We also excluded reviews, systematic reviews, meta-analyses, letters, personal opinions, conference abstracts and book chapters.

DATA EXTRACTION

Three reviewers independently performed the extraction of data from studies included.

RESULTS

Seventeen studies met our inclusion criteria and were included in the final review. Pooled analyses showed that those with the highest Citrus fruit intake compared to the lowest intake had a 50% reduction in risk of oral cavity and pharyngeal cancer (OR 0.50; 95% CI 0.43-0.59).

CONCLUSION

The studies included in this review and meta-analysis showed an inverse association between Citrus fruit intake and oral cancer.