Cancer research captivates high schooler in HHMI-funded Student and Teacher Program at NIH. Grants in Action
After school, most high school seniors favor diversions like malls, movies or hanging out with friends. Henrietta Ocheni prefers doing cancer research.
That's not to say that the 18-year-old senior at Walter Johnson High School in Bethesda, Md., is single-minded about what she enjoys. In addition to participating in the HHMI-sponsored Student and Teacher Program (STP) at the National Institutes of Health, Ocheni finds time to sing in a gospel choir and to preside over her school's French Honor Society and Black Student Union. "Sometimes I even go to the mall or the movies," she insists.
Yet four afternoons a week Ocheni can be found in the National Cancer Institute's Laboratory of Cellular Carcinogenesis and Tumor Promotion, isolating proteins, culturing skin-cancer cells or running sophisticated lab tests to measure the effects of an enzyme inhibitor.
Working alongside her preceptor or instructor, postdoctoral fellow Elizabeth Joseloff, Ocheni has focused on an enzyme called protein kinase C delta (PKC∂). PKC∂ helps regulate the normal cycle of cell growth, differentiation and death. In normal cells, it may function as a tumor suppressor. But phosphorylation, a biochemical reaction that results in the addition of phosphate molecules, inactivates PKC∂ in certain tumor cells, permitting them to proliferate uncontrolled.
"The question was, what phosphorylates PKC∂?" Ocheni says. She has spent this school year seeking the answer.
In STP the students learn to define a scientific problem and state a testable hypothesis. Then, with guidance from the NIH scientists who serve as their preceptors, the students design and carry out experiments, analyze data, draw conclusions and present their findings at a HHMI dinner symposium and an annual NIH Poster Day.
This year's symposium is scheduled for Thursday, May 6, at HHMI headquarters in Chevy Chase, Md. Guests will include Montgomery County Schools Superintendent Paul L. Vance, HHMI President Purnell W. Choppin, U.S. Rep. Connie Morella, State Sen. Leonard Teitelbaum, members of the Montgomery County Board of Education and the Montgomery County Council, parents and science teachers.
As she prepares to present her research before this audience, Ocheni's stage fright is surpassed by her enthusiasm for what she has learned, not only about PKC∂ but also about another enzyme called src kinase and other molecular players in the drama of skin cancer. She has caught a glimpse of one of the hottest topics in basic science research today: signal transduction, the way a cascade of biochemical triggers act as switches, turning certain molecules on and others off.
"I learned to do tissue culture to isolate proteins from cells, to perform western blotting that measures the levels of PKC∂ and src kinase, and to conduct immunoprecipitation assays to analyze the phosphorylation effects of src on PKC∂," she explains. "Then we treated two kinds of benign skin cells with a src inhibitor. We found that the src inhibitor does not affect overall levels of src kinase or PKC∂, but the inhibitor does decrease phosphorylation of PKC∂. We concluded that the src kinases are involved in phosphorylation of PKC∂ ."
The answer to her first research question helped Ocheni formulate her next one: "If we prevent phosphorylation of PKC∂ by using a src inhibitor, what will the biological effects be on cell differentiation and the cell cycle. In other words, can we reverse the process?"
Ocheni will spend this summer before she leaves for college working with Joseloff on the answer to that question.
During their year together, student and preceptor have caused unexpected turns in each other's career paths.
Ocheni, who emigrated from Nigeria with her family when she was 10, says she has always wanted to be a doctor but, until her STP experience, had never considered medical research. "In school I only got to work in the lab for about half an hour every two weeks, and the experiments usually worked," she says. "When I got to NCI, I found out that experiments sometimes don't work, and sometimes you learn more from the ones that don't."
Before this year, Ocheni knew she liked science. "But I did not know what it takes to be a researcher. Now I like it even better." Of Joseloff, she says: "She helped me set goals, to know that this is really what I want to do." Now aiming for both M.D. and Ph.D. degrees, Ocheni wants to conduct research and practice clinical medicine.
Joseloff earned a Ph.D. in cancer biology at the University of Arizona before coming to NCI to do postdoctoral research. She expected to spend the rest of her working life in a research lab, but she has so enjoyed guiding Ocheni that now she's considering teaching as well.
"Henrietta is an incredible student, really sharp and highly motivated, very curious and such a hard worker," Joseloff says. "It's been wonderful to see her develop." Joseloff is eager to welcome another STP intern into her lab.