Trigger Ferroptosis by increasing cellular IRON & drug ERASTIN.

Lynch’s No1: Hypothesis: Ferroptosis can be triggered in Metastatic Uveal Melanoma patients by increasing cellular IRON and using the ferroptosis inducing drug ERASTIN.

Abstract: Uveal or Ocular melanoma (OM) has a very poor prognosis when it spreads. There is no known cure. A correlation between low iron has been noted with metastatic progression. Unusual OM remission cases have been connected with ferroptopic inducers. Zinc has also been connected with OM and ferroptosis. The drug erastin is known to induce ferroptosis. Ferroptosis is iron dependent. BAP1 loss in OM is known to inhibit ferroptosis. The combination of these factors presents a novel opportunity to treat this disease with erastin and increased iron.

Background: Uveal or Ocular melanoma (OM) is a rare cancer of the eye. Incidence rates are circa 5.1 per million (USA) to as high as 9.5 per million (Ireland) [1] . It can be treated with some success if detected early by radiation or removal. However when it metastasises (50% rate) it has a record of being lethal with death in 2-9 months, a figure holding steady these past years. It has proven not to be responsive to traditional standards of treatment [2].

It has become very popular in this internet age for patients and those around them to search the published online medical literature for items of OM interest. Recently a paper on the therapeutic use of Zinc in cancer was unearthed [3]. More interestingly to this author is that a successful case reported was that of a uveal melanoma patient. This raised the question why did Zinc (Zinc gluconate (50 mg chelated elemental Zn2+)) work in such a fashion.

Zinc intoxication of cells induces ferroptosis in non-small cell lung cancer (NSCLC) cancer cells [4]. Zinc’s relationship with H2O2 is of interest here and raises questions of similarities with the action of acerbic acid (Vitamin C) injections.

Ferroptosis is a new type of cell death that has been discovered in recent years and is usually accompanied by a large amount of iron accumulation and lipid peroxidation during the cell death process; the occurrence of ferroptosis is iron-dependent. Ferroptosis inducing factors can directly or indirectly affect glutathione peroxidase through different pathways, resulting in a decrease in antioxidant capacity and accumulation of lipid reactive oxygen species (ROS) in cells, ultimately leading to oxidative cell death.

On a parallel search evidence was discovered about Artesunate (ART) which is a derivative of artemisinin, the active principle of the Chinese herb Artemisia annua L. Artesunate is approved for the treatment of multidrug-resistant malaria and has an excellent safety profile. It has been shown that Artesunate, apart from its anti-malarial activity, has cytotoxic effects on a number of human cancer cell lines. This report featured an OM patient still alive after 47 months with a median survival of 2-5 months while being treated with ART [5]. ART is described as a ferroptopic agent.

By way of anecdotal evidence from the OM community it has been observed that those who die of metastatic OM tend to have very low iron levels. Those that are living longer tend to have normal iron levels. As ferroptosis requires iron, supplementation for anaemic patients would seem to be necessary. Consideration should be give to iron infusions and or blood transfusions to help achieve the ferroptopic iron levels required.

Loss of the tumour suppressor BRCA1-associated protein 1 (BAP1) is an indicator of metastases in OM [6]. BAP1 inhibits cystine uptake by repressing SLC7A11 expression, leading to elevated lipid peroxidation and ferroptosis [7].

System xc− was recently described as the most upstream node in a novel form of regulated necrotic cell death, called ferroptosis. In this context, the small molecule erastin was reported to target and inhibit system xc−, leading to cysteine starvation, glutathione depletion and consequently ferroptotic cell death. Although the inhibitory effect of erastin towards system xc− is well-documented, nothing is known about its mechanism of action. System xc− is one among many amino acid transporters expressed in the plasma membrane of mammalian cells. This transporter is composed of xCT (SLC7A11), which is the substrate-specific subunit hence the BAP1 loss connection[8].

The drug Erastin triggers oxidative, iron-dependent cell death. Cell death triggered by erastin is significantly inhibited by antioxidants (e.g., α-tocopherol, butylated hydroxytoluene, and β-carotene) and iron chelators, suggesting that ROS- and iron-dependent signaling is required for erastin-induced ferroptosis. Erastin can directly bind to VDAC2/3 in BJeLR cells. Knockdown of VDAC2 and VDAC3, but not VDAC1, leads to erastin resistance. Erastin has the ability to reduce glutathione level by directly inhibiting cystine/glutamate antiporter system Xc− activity, with activation of the ER stress response. Erastin shows a dose-dependent effect, and 30 μM of erastin displays the most dramatic effect[9].

2020 has seen some exciting new research published. One such paper “The epigenetic regulators and metabolic changes in ferroptosis-associated cancer progression” [10] has surfaced. Its a very dense work brimming with information which inter alia connects OM and loss of BAP1 with ferroptosis disruption.

Hypothesis:

It is hypothesised that:

• Metastatic Uveal Melanoma cells can be killed by a process called ferroptosis.
• Available Iron at the cellular level is needed.
• For speed infusions and transfusions should be considered to meet this iron requirement.
• Zinc levels should also be investigated and acted on if appropriate.
• The ability of the body to trigger ferroptosis may be inhibited and may need help.
• The drug Erastin induces ferroptosis but needs iron to be available.
• Its use with increased iron levels should be evaluated firstly in a BAP1 negative metastatic uveal melanoma setting.

No evidence of erastin use in OM has been found in the literature in this exercise. Consideration should be giving to known erastin inhibitors ( LSH, NFS1, GPX4 , SCD1 and FADS2) and their impacts with the suggested patient profile. In the absence of any known viable working therapy this hypotheses should be tested at the earliest opportunity. In particular where all options have been exhausted and the “Right to try before I die” argument comes into play, it should be considered.

Declaration of Competing Interest:

The author declares that he has no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

The author:

Mr. Brendan Lynch is the surviving spouse and carer of a deceased uveal melanoma patient Ms. Belinda Honeyman-Lynch. He has continued the passionate search for a cure. He is an active member in the OM community at national and international levels. He is also a founding member of Ocular Melanoma Ireland (www.ocumirl.org). He is a retired civil servant who's only declared interest is the discovery of a cure for ocular melanoma.

Bibliography

1: Caroline Baily, Valerie O’Neill, Mary Dunne, Moya Cunningham, Giuseppe Gullo, Susan Kennedy, Paul M. Walsh, Sandra Deady, Noel Horgan, Uveal Melanoma in Ireland https://www.researchfoundation.ie/app/uploads/2019/05/Uveal-Melanoma-in-...,

2: Jessica Yang, Daniel K. Manson, Brian P. Marr, and Richard D. Carvajal, Treatment of uveal melanoma: where are we now? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824910/,

3: , Unlocking Zinc’s Potential to Fight Cancer. https://www.cancertreatmentsresearch.com/unlocking-zincs-potential-to-fi...,

4: , Zinc intoxication induces ferroptosis in A549 human lung cells. https://www.ncbi.nlm.nih.gov/pubmed/30968088,

5: Berger TG1, Dieckmann D, Efferth T, Schultz ES, Funk JO, Baur A, Schuler G., Artesunate in the treatment of metastatic uveal melanoma--first experiences. https://www.ncbi.nlm.nih.gov/pubmed/16273263, 2005

6: , Clinical Characteristics of Uveal Melanoma in Patients With Germline BAP1 Mutations. https://www.ncbi.nlm.nih.gov/pubmed/25974357,

7: , BAP1 links metabolic regulation of ferroptosis to tumour suppression. https://www.ncbi.nlm.nih.gov/pubmed/30202049,

8: , The ferroptosis inducer erastin irreversibly inhibits system xc− and synergizes with cisplatin to increase cisplatin’s cytotoxicity in cancer cells. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5772355/,

9: , Erastin is a ferroptosis inducer. Erastin binds and inhibits voltage-dependent anion channels (VDAC2/VDAC3). https://www.medchemexpress.com/Erastin.html,

10: , The epigenetic regulators and metabolicchanges in ferroptosis-associated cancerprogression. https://molecular-cancer.biomedcentral.com/track/pdf/10.1186/s12943-020-... ,