In previous blog posts, I discuss the importance of formal courses in tumor biology and nutrition for medical students, as well as for practicing physicians, especially oncologists.
We all know that pathogenic bacteria can develop resistance to specific antibiotics. I wonder whether the poor response to specific anti-tumor drugs in some cancer patients, and/or the development of remissions, are related to the ability of cancer cells to undergo heteroploid transformation and the specific selection of a karyotype.
I recall from my research as a cell biologist with the Department of Cancer Research at the University of Saskatchewan in Saskatoon (from 1961 to 1965) where I demonstrated that if a single cancer cell from a cell line was isolated and then allowed to undergo numerous cell divisions in cell culture – I used the tumor cell line called HeLa – that chromosomal analysis of many cells from this population showed cells with varying number of chromosomes. This phenomenon is called heteroploid transformation. Chromosomal values in my experiment ranged from the low 50’s to the 70’s, with a stem cell line in the early 60’s. (Hrushovetz, S.B. Importance of heteroploid transformation in the etiology of neoplasia. Proceedings of the 17th Western Regional Group MRC/NCI. 1963).
For my Master’s degree in Biochemistry from the University of Alberta, I had earlier shown that the addition of specific amino acids to the culture medium on which the cereal plant pathogen – called Helminthosporium sativum – was sub-cultivated could alter the virulence of this pathogen in producing root rot disease. (see publication Phytopathology 47:261-264. 1957).
Alternatively, these experiments could be interpreted as demonstrating that for a pathogen to retain its virulence, it requires the presence of specific nutrients in its environment.