Page 46 - Hormel Report 2023

Rebecca Morris, PhD
“With most techniques in science we can learn new things, but with a microscope we can see them. Thus, we can visualize stem cells with fluorescence microscopy and follow them when they are behaving normally, as
well as when they become the roots of cancer.”
Rebecca Morris
46 | THE HORMEL INSTITUTE Stem Cells and Cancer
PROFESSOR
// UNIVERSITY OF MINNESOTA
Tantalizing evidence has supported the existence of epithelial cells in blood and bone marrow since the advent of reverse
transcription polymerase chain reaction. First discovered in patients with breast and prostate cancer, these circulating epithelial cells were quickly identified as metastatic epithelial cells. Perplexingly, however, traces of cytokeratin mRNAs were also found in the blood and bone marrow of many normal volunteers. These were dismissed as artifacts, or metastases from an occult tumor, or in some cases, circulating fetal cells. Our interest in these rare circulating epithelial cells was ignited by our recently published data demonstrating that cells of bone marrow origin are recruited to chronically hy- perplastic epidermis and developing cutaneous neoplasms where they became as epidermal cells. They produced epidermal cytokeratins, proliferated, differentiated, desquamated, and persisted as epithelial cells over many months, still maintaining the green fluorescent protein or the Y-chromosome of their bone marrow origin. We are currently isolating and characterizing these cells in vitro, in vivo, and in silico.
Current Research Projects:
Non-melanoma skin cancers (NMSCs) are a serious and growing public health problem despite a plethora of sunscreens and repeated calls for sun avoidance. In some patients, NMSCs become intractable and ultimately deadly leading us to wonder whether some of the cancer cells might originate in the bone marrow, an incubator for numerous stem and progenitor cells. We have explored the role of bone marrow derived cells (BMDCs) in cuta- neous malignancy. We used allogeneic bone marrow transplantation (BMT) and a multistage cutaneous carcinogenesis model to probe recruitment of BMDCs in skin tumors initiated with the carcinogen, dimethylbenz[a]anthracene (DMBA), and promoted with 12-O-tetradeca- noylphorbol-13-acetate (TPA). Donor BMDCs clustered in the recipient lesional epithelium, expressed cytokeratins, proliferated, and stratified. We detected cytokeratin induction
in plastic-adherent bone marrow cells (BMCs) cultured in the presence of filter-separated keratinocytes (KCs) and bone morphogenetic