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By Joey Garcia, University Communications and Marketing 

Deep beneath the icy waters surrounding Antarctica, a small marine organism may hold clues to a future cancer treatment. Researchers from USF recently returned from a six-week expedition in one of the most remote environments on Earth to study a species of ascidian, or sea squirt, that contains a bacterium capable of killing melanoma cancer cells.

The discovery was first made 20 years ago by USF chemistry Professor Bill Baker, whose research uncovered the organism鈥檚 remarkable cancer-fighting potential. He鈥檚 now once again helping lead efforts to better understand the compound and explore whether it could someday contribute to new therapies for patients battling melanoma, one of the deadliest forms of skin cancer.

More than half of FDA-approved drugs originate from natural sources. We first discovered this ascidian produces a bacterium that contains a toxic compound that kills melanoma cancer cells while not harming normal human cells. That selectivity is critical in drug development because you want to treat the disease without harming the patient.

Bill Baker
USF Chemistry Professor

Baker鈥檚 previous marine discoveries have led to patented compounds with potential applications against diseases including drug-resistant malaria, cancer and antibiotic-resistant infections 鈥� underscoring the pharmaceutical promise hidden within ocean organisms.

RETURNING TO ANTARCTICA

For the Baker Lab, Antarctica provides a unique environment for studying organisms with potential medical applications, including those relevant to melanoma research. The lab has specifically focused on marine invertebrates because many rely on chemical defenses to survive in the harsh ocean environment, producing compounds that can deter predators and disease.  

鈥淭he continent is unique because it has been geographically and environmentally isolated for millions of years,鈥� Baker said. 鈥淎s a result, species in Antarctica have had time to evolve independently, leading to highly specialized organisms. The ascidians we study are adapted specifically to this environment and are not found anywhere else.鈥�

As Baker advised the 2026 expedition from land, USF was represented in Antarctica by diving safety officer Ben Meister and postdoctoral researcher Sam Afoullouss from the Baker Lab. 

 鈥淥ur expedition focused on determining where the ascidian鈥檚 melanoma-killing bacterium occurs and how widespread it is,鈥� Afoullouss said. 鈥淲e also wanted to understand how it lives inside the organism and how that connects to the compounds linked to melanoma research.鈥�

The findings could help researchers determine how the compounds are produced naturally and whether they can eventually be harnessed for medical applications.

EXPLORING THE ANTARCTIC FLOOR

The ascidians in the expedition are typically found at depths between 60 and 80 feet, often along sloped or vertical seafloor surfaces where water currents are strong. These currents help deliver nutrients that sustain the organisms. 

Collecting the ascidians required multiple dives and the use of two remotely operated vehicles to explore deeper waters to identify new collection sites, while also helping map the distribution of ascidians across different depths and locations along the Antarctic Peninsula.

鈥淥n average, our dives were about 25 to 35 minutes at a time with a maximum of 130 feet,鈥� Meister said. 鈥淏ut in Antarctica, you鈥檙e dealing with ice, leopard seals, changing seas and sometimes very limited visibility. Every dive must be carefully planned to balance getting the work done while keeping everyone safe.鈥�

That level of planning is essential not only for safety but also to ensure samples are collected efficiently and preserved for lab analysis where they can be studied for their chemical and biological properties. Preserving the integrity of the samples is important because even small changes in the organisms or bacteria could affect scientists鈥� understanding of how the compound functions. 

COLLABORATIVE TEAM SCIENCE

Now that the expedition has returned to land, the research enters its most critical phase.

Divided among multiple teams, the specimens move through a series of analyses, with researchers focusing on DNA, chemistry and biological assessments. This process could take months to years but is essential for translating early discoveries into meaningful scientific progress, particularly in fields like cancer research where multiple areas of expertise are required.

鈥淭his research is important both environmentally and medically,鈥� Baker said. 鈥淲e are learning how organisms use symbiosis to survive in extreme conditions, which is still largely unknown in cold-water ecosystems like Antarctica. Understanding the source and function of this compound is critical if we hope to develop it into a drug.鈥�

Discoveries like this represent the early stages of a long process, but they could eventually help researchers identify new ways to treat complex diseases.