Advances in imaging may help gather more datasets on tumor development from a single experiment.
Researchers at Mount Sinai in New York are using advances in tissue preparation, imaging, image analysis, and registration to explore the biology underlying the well-known comorbidity between melanoma and Parkinson’s disease (PD). The project recently garnered a $100,000 pilot grant co-funded by the Michael J. Fox Foundation, also in New York, and the Melanoma Research Alliance, Washington, DC.1
Having melanoma increases risk for PD, and vice versa, said Deanna L. Benson, PhD. She is a professor of neuroscience at the Friedman Brain Institute and director of Microscopy and Advanced Bioimaging Core at Mount Sinai’s Icahn School of Medicine.
Epidemiological studies, usually from the PD perspective, have repeatedly shown an increased risk among patients with PD to have, develop, or have had melanoma, and vice versa.2-4 The link has been known for many years, Benson said. “And we realized that nobody had really delved into it.” Benson is collaborating with cancer researcher Jose Javier Bravo-Cordero, PhD, associate professor of hematology and oncology at Mount Sinai in New York.
“We decided to work on this problem because we thought that maybe together, we could discover the biology that underlies this shared risk.”
Upon starting their research, the investigators quickly realized they could take advantage of technical advances that have occurred in the last few years to analyze tumor development dynamically. Specifically, Benson explained, 2-photon microscopy allows researchers to image tumor-cell behavior intravitally in mice as tumors are growing. “You can label the vasculature, axons, and tumor cells with fluorescent markers. Then you can observe the behavior of those elements and relationships to each other dynamically.”
Typically, Benson said, cancer researchers study tumor composition using different methods applied in several separate experiments. “We found that we were losing data by conducting separate studies for each outcome, and that it would be far more beneficial to incorporate these new technologies to obtain multiple datasets from a single experiment.”
Because 2-photon microscopy cannot access the entire tumor, the project will also incorporate a new fast 3D clearing protocol to visualize the entire tumor.5 “Lipids are removed from a fixed tumor sample, which means you actually render the tumor transparent. Then you use a light sheet microscope to rapidly image through the whole tumor. The idea is that in a fixed sample that has been cleared, we can examine and quantify relationships among each of these tumor-associated components, like vasculature, tumor cells and axons, and those data can be registered and compared to the videos that were captured using 2-photon microscopy.”
Another collaborator, StylianosKosmidis, PhD, adjunct associate research scientist in the Mortimer B. Zucker Mind Brain Behavior Institute at Columbia University in New York, has developed a technique that can reverse the clearing process and permit standard sectioning through and immunolabeling the tumor tissue. These preparations, said Benson, can be viewed at very high magnification, permitting the identification of cell types and other features that can then be registered to the other 2 datasets.
The project’s goal is to develop an imaging-based pipeline to maximize what investigators can learn from tumors in each stage of analysis. “The idea is to capture data at several different levels, from macro to micro, from the same samples.”
Researchers well then use this pipeline to compare tumors growing in wild-type mice to those growing in mice carrying a knock-in of a mutation—specifically the G2019S mutation in the leucine-rich repeat kinase 2 (LRRK2) gene—that greatly increases PD risk in humans. “The single-point mutation increases LRRK2 kinase activity.”
At press time, investigators had begun the process of generating tumors in a mouse model. “We already have experience generating tumors in these mouse models and comparing tumor growth. We’re currently troubleshooting the tissue clearing method this summer, and we should be ready to start with live imaging at the beginning of fall.”
Benson reports no relevant financial interests.
1. Melanoma Research Alliance. Melanoma Research Alliance announces $13 million in grants to advance melanoma prevention, detection & treatment.https://www.curemelanoma.org/assets/Uploads/MRA-Grant-Awards-2022.pdf. May 19, 2022. Accessed June 16, 2022.
2. Olsen JH, Friis S, Frederiksen K. Malignant melanoma and other types of cancer preceding Parkinson disease. Epidemiology. 2006;17(5):582-587. doi:10.1097/01.ede.0000229445.90471.5e
3. Ascherio A, Schwarzschild MA. The epidemiology of Parkinson's disease: risk factors and prevention. Lancet Neurol. 2016;15(12):1257-1272. doi:10.1016/S1474-4422(16)30230-7
4. Dalvin LA, Damento GM, Yawn BP, Abbott BA, Hodge DO, Pulido JS. Parkinson Disease and melanoma: confirming and reexamining an association. Mayo Clin Proc. 2017;92(7):1070-1079. doi:10.1016/j.mayocp.2017.03.014
5. Kosmidis S, Negrean A, Dranovsky A, Losonczy A, Kandel ER. A fast, aqueous, reversible three-day tissue clearing method for adult and embryonic mouse brain and whole body. Cell Rep Methods. 2021;1(7):100090. doi:10.1016/j.crmeth.2021.100090