While some divers search the depths of the Great Lakes for gold, a band of scientists have found a different kind of treasure at the Lake’s floor. A species of fungus called Alternaria was extracted from sediment collected in Lake Superior, Lake Michigan and Lake Huron. The fungus is showing promising signs that it could eventually be used to target and combat Ewing’s Sarcoma.
Ewing’s Sarcoma is a form of cancer which grows tumors in the bone and surrounding tissue. Although considered rare, it’s the second most common type of bone cancer in children. According to St. Jude’s Children’s Research Hospital, about 200 American children and young adults are diagnosed with Ewing’s Sarcoma each year.
“Each of these tumors,” University of Oklahoma Regents Professor Dr. Robert Cichewicz explains, “They’re different enough that we give them different names: they behave in different ways, they strike people at different times in their life in different organs of the body. The reason for that is because they have different biology. If you can find a compound that messes with that individual set of biological signatures which [in turn] makes that cancer cell line unique, then you’re talking about the potential for developing a [new] drug.”
The process of testing the fungus is a relay. First, sediment is excavated from the Great Lakes. The sediment is sent to labs that isolate the fungus,grow it into a larger supply and extract the natural products. The voyage concludes at a lab where the extracted compounds are tested against cancer cells. Running each leg of this relay are professors: Dr. Mark Luttenton, Dr. Andrew Miller, Dr. Cichewicz and Dr. Susan Mooberry. Each team member represents a different university and area of expertise.
Cichewicz is a Michigan native who attended Grand Valley State University for his Bachelor’s Degree. During his time there, he took several courses with ecologist Dr. Mark Luttenton, who is now an essential part of Cichewicz’ research team. Luttenton is responsible for supplying the fungi by digging up Great Lakes sediment. He then ships it to the labs of Cichewicz and also to plant biologist, Dr. Andrew Miller at the University of Illinois. After Cichewicz and Miller separate and cultivate the Alternaria fungus to extract a chemical compound and ship it to a pharmacology professor, Susan Mooberry at the University of Texas Health San Antonio. Mooberry’s task is to test the compound on Ewing’s Sarcoma cells.
“Because of these collaborations, we’re looking at a chance to actually help people,” Cichewicz said. “The fungus itself; what makes it remarkable to us is the fact that they gain this particular molecule called ultratoxin. We can find lots of things that kill human cells, but we don’t want things that just indiscriminately kill, we want things that kill in a very selective way.”
Having grown up in Michigan, Cichewicz said it was the absence of information on fungi in the Great Lakes that inspired him to look there for a fungus to produce ultratoxin.
“The scientific literature has nothing to say in terms of the fungal diversity sitting right there throughout the Northern United States,” said Cichewicz. Miller confirmed Cichewicz’ assessment that there were only about 13 species of Great Lakes fungi documented in scientific publications.
“I found that just remarkably small given that the Great Lakes are huge, they’re one of the largest freshwater bodies on earth,” he said. “It turned out that the Great Lakes are just this black hole in terms of knowledge about what fungi exist there.”
There are now more than twice as many known species of fungi from the Great Lakes, scooped up by Luttenton. During the screening process, the compound ultratoxin only manifested once, but that was enough to grow and expand that particular Alternaria to extract the compound.
“One of the challenges about fungi is that every fungus has its own unique kind of dietary requirement,” said Cichewicz. “We don’t have time to figure out which every fungus wants specifically.”
Initially, Cichewicz used two-pound cans of potato-based dextrose powder, mixed with water to create “broth media” to keep the fungi alive. One can of that fungal growth nutrient costs $100-150 and can yield around 20 liters.
“It’s a decent amount but given the scale of what we do in the lab we would burn through that really quickly,” said Cichewicz. In an effort to conserve funding and resources, Cichewicz turned to the aisles of Walmart to find a cost-effective food to grow fungi on a larger scale. It took many months of trying every aisle in the grocery store before he tried feeding them plain General Mills Cheerios.
“When you’re going to the checkout, Cichewicz laughs, "with 300 boxes of cheerios inevitably you get the question of ‘well wait where’s the milk?’”
Apparently, the fungi prefer plain Cheerios over generic or sweetened Cheerio varieties. The plain Cheerios are a mixture of different carbohydrates and vitamins, without excessive salt and preservatives, which would kill the Alternaria. Name-brand Cheerios hold their shape better than generic Cheerios, which means there is a greater surface area to maximize fungal growth. Typically, after four weeks of growing, the fungi create fuzzy green and orange “ghost Cheerios,” by taking the shape of the Cheerios they have consumed.
The Cheerio-shaped fungi are immersed in ethyl acetate alcohol to extract the natural products from the fungi. This process is similar to submerging a tea bag in water to infuse the flavors into the brew. The natural products are then purified by chemists to separate the essential molecule to be shipped to Professor Mooberry’s lab at the University of Texas Health-San Antonio to test its effects on cancer cells.Cichewicz has been partnering with Mooberry for many years to develop cancer pharmaceuticals.
“She’s a phenomenal cancer biologist,” praised Cichewicz, “We’ve really been able to form a great partnership of exploring all sorts of fungal sources as well as plants.” Through the combined labors of both labs, they have organized a collection of more than 30,000 fungi.
“We have several leads that are coming out of that we feel quite excited about in terms of their applications to cancer treatment.It’s been phenomenal.”
Their collection has been primarily supplied by two sources: The National Cancer Institute Collection and a citizen science soil collection program called “What’s in Your Backyard.”
“The reality is collecting samples,” Cichewicz said, “you want to get as many places sampled-get out there and get diverse areas but it takes time and money.” The soil collection program Cichewicz started is a free program in which people all over the world can sign up on the website WhatsInYourBackyard.org to receive a soil collection kit, view a detailed video tutorial and eventually track the process of their soil sample once it has been submitted to the lab.
The Citizen Soil Collection program and the ultratoxin research are examples of collaboration enabling a broader scope of possibilities at a lower cost, creating disruptive innovation.
“This has been great forming these partnerships-friendships with people who are obviously great at what they do and can just enhance the work that you do,” said Cichewicz. “I could do natural products all by myself but it would not be anywhere near having the impact it does.”
Since the ultratoxin is still in the discovery stage of drug development, it could take 10-20 years before this chemical compound is put in a plastic, orange cylinder.
“We are seeing all great signs for the molecule right now and we are pushing forward with it, doing further testing,” said Cichewicz. “But it does have a long road ahead of it.”
