Gettysburg College alumnus John Pawelek ’63 and a team of researchers have released a study that may answer the question of how cancer cells travel from the site of a tumor to other organs and tissues in the human body.
The research team, comprising Yale Cancer Center scientists and colleagues at the Denver Police Crime Lab and the University of Colorado, has found evidence that a human metastatic tumor can arise when a leukocyte (white blood cell) and a cancer cell fuse to form a genetic hybrid. Their study was published in the peer reviewed online journal PLoS ONE.
Their work explores a theory that was proposed as an explanation for metastasis more than a century ago. Until now, the theory was unproven in human cancer because genetic differences between cells from the same patient cannot be distinguished.
“Our results provide the first proof in humans of a theory, proposed in 1911 by a German pathologist, that metastasis can occur when a leukocyte and cancer cell fuse and form a genetic hybrid,” said Pawelek, a member of the research faculty in the Department of Dermatology, Yale School of Medicine. “This could open the way to new therapy targets, but much work needs to be done to determine how fusion occurs, the frequency of such hybrids in human cancers, and the potential role of hybrids in metastasis.”
Pawelek reconnected with Gettysburg College after being invited to a departmental reception for faculty and students by Prof. Kazuo Hiraizumi, chair of biology at the time. Kazuo introduced him to Prof. Ralph Sorenson, which led to Pawelek attending Sorenson’s cell biology course and giving some lectures on cancer at the end of the year—a mini-tradition that happily continues today.
Sorenson, who said Pawelek’s findings “challenge the way most scientists think about metastasis,” credits Pawelek as a guiding influence in the design of the cell biology lab course and research conducted at Gettysburg College.
“He (Pawelek) encouraged us to think about phagocytosis (cells eating cells),” Sorensen said. Their operating thesis is that if cancer cells are indeed fusion products between macrophages and the primary cancer cell, then metastatic cell lines should display one of the cardinal features of macrophages, the ability to undergo phagocytosis.
Sorensen set out to establish a research protocol (assay) and a method of observing this feeding behavior using fluorescent beads, which are ingested by the melanoma cell. It is research that has been ongoing. Mary Fakunle ’12 and Shane Swink ’13 worked with Sorensen on independent but related projects in each of their senior years. Fakunle is a researcher at the National Institute on Drug Abuse in Baltimore. Swink will begin a masters program in Biomedical Science at the Philadelphia College of Osteopathic Medicine in the fall.
Pawelek values his collaboration with Gettysburg College alumni and undergraduates. "It has been a real pleasure to re-connect with Biology at Gettysburg after so many years, but the icing on the cake has been helping to advise Ralph’s honor students,” he said. “They are now working on projects directly related to my cancer cell fusion studies at Yale. Indeed, we are now analyzing some of their samples in our own lab. It is my fond hope that someday soon we will be able publish it altogether in a grand Gettysburg-Yale partnership."
This summer senior biology major Mariah Johnson’14 and Sorensen are exploring a different tracking method using fluorescent stains that will help them—and perhaps Pawelek—further understand fusion in melanoma. In the lab, melanoma cells eat neighboring melanoma cells.
“So far, the instances we have seen of fluorescent cells within non-fluorescent cells strongly indicate the cells are eating their siblings. Metastatic tumor cells utilize glucose very inefficiently and the eating of their neighbors may provide the food supply necessary for the secondary tumor to survive.” Sorensen said.
Johnson said research drew her into primary literature and made her realize how important her class work is. It also accelerated her career plans.
“I had planned to spend one or two years [after graduation in 2014] working as a laboratory technician, but now I am applying to graduate school this fall,” Johnson said. “I hope to eventually balance research and teaching biology to undergraduates.”
Their summer research is supported by a grant from the Howard Hughes Medical Institute (HHMI) and a College research and professional development grant to Sorensen. Posted: Thu, 1 Aug 2013