Deeper pigmentation of skin cells protects them from radium and X-ray treatments
contributed by Caroline Edwards
Animals, Cellular biology, Experimental, Fundamental research, Historical figure, Lab, Medicine, North America, Person of Color, Physiology, Race/ethnicity, Societal Relevance, Woman
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Jewel Plummer Cobb. 1956. Effect of in Vitro X Irradiation on Pigmented and Pale Slices of Cloudman S91 Mouse Melanoma as Measured by Subsequent Proliferation in Vivo234. JNCI: Journal of the National Cancer Institute 17(5): 657–666 link
Ellen Elliott. Women in science: Jewel Plummer Cobb (1924-2017) link
Jewel Plummer Cobb was a biologist, cancer researcher, professor, and an advocate for increasing the representation of women and students of color in universities. Cobb’s research included work on the relationship between melanin and skin damage, and on the effects of hormones, ultraviolet light, and chemotherapy agents on cell division.
Biography in brief
Jewel Plummer Cobb grew up in Chicago and matriculated at the University of Michigan, but after being put in segregated housing and excluded from the campus social life, Cobb transferred to Talladega College, a historically black college in Alabama. She graduated in two years with a BA in Biology and went on to earn her masters and doctorate degrees from NYU. She accomplished many things in her life, one of which was successfully culturing cancer cells directly from patient biopsies, which she used to study the effects of different chemotherapy drugs on cellular morphology, migration, and growth. In 1969 Cobb became Dean of Connecticut College and began creating dynamic educational programs that encouraged minority and women students to pursue STEM careers. She started one of the first post-baccalaureate programs for minority students, which supported college graduates wanting to enter post-secondary medical training. Part of her activism was speaking out against the entrenched inequalities she perceived across multiple fields of science, and outlined the subtle and flagrant ways society discourages young women from contributing to scientific progress in “Filters For Women in Science.”
Axes of identity & underrepresentation
I think it is very likely that Cobb has been under-appreciated because of her identity, but didn’t read anything about it specifically
Take home message of study
Cobb looked at the effect of X rays on pigmented and pale slices of melanoma by exposing tissue slices of both pigmented and pale areas of the same tumor to varying doses of X rays, implanting them in mice, and measuring their growth and viability. She found a difference in radiosensitivity of pigmented and pale tissue, and realized it was related to the amount of melanin per unit volume of tissue. Cancer cells with more melanin survived in vitro radiation experiments, while lightly pigmented cells from the same tumor did not.
A stock image of a stained melanoma under the microscope
Key Research Points
This figure shows the diameter of pigmented and pale tumors over several weeks after exposure to three different radiation levels: 2500, 2800 and 3000 r. At 2500 r, the pigmented and pale tumors grew at similar rates, but at higher radiations (especially 3000 r), the radiated pigmented tumor was able to survive and grow throughout the 13 weeks measured, whereas the radiated pale tumor did not persist past 7 weeks.
Cobb found that deeper pigmentation of skin cells protected them from radium and X-ray treatments cancer cells with more melanin survived in vitro radiation experiments, while lightly pigmented cells from the same tumor did not. This is the first evidence for the UVA/UVB shielding properties of melanin, which explains the large disparity in skin cancer rates among people with dark and light skin.