On the other hand, the story becomes more interesting, if the experimental results obtained contradict the hypothesis and do not match the earlier published results. This is all the more interesting!!! Most of the times, it so happens that contradictory results challenge a young researcher, especially a Ph.D. student when the Ph.D. student tries giving up or else changes the topic of research for ease or convenience. However, this is not the right temperament for doing science.
When confronted with contradictory results, it becomes all the more interesting for adding life to the piece of work. By adding life, I mean to make more sense out of the data. During such times, one needs to relook into the data, of course, validate the same with enough replicates and then do a brainstorming. Most of the times, one can reach a very interesting mechanism that might be responsible for the contradictory result.
I am giving a specific example. Breast Cancer Stem cells and triple negative breast cancer cells express high levels of pluripotency markers such as Oct 4, Nanog and Sox 2. This is a blanket statement. However, single cell analyses from breast tumor tissue samples have shown a hierarchical presence of CSC markers, pluripotency markers and EMT markers depending on the stages of differentiation. Also, it varies as per the type of breast cancer that correlates with the cell lines, as well (ER-positive/Luminal-MCF7 cell line and ER-negative/Basal-MDMMB231 cell line) (Akrap et al. 2016). In this work, the authors demonstrated that in triple negative breast cancer (TNBC) CSCs, proliferation is associated with differentiation, accordingly, quiescent CSCs maintain CSC phenotype and proliferating CSCs lose CSC phenotype. More recently, the role of Vitamin C in enhancing the CSC phenotype has been published by Ramezankhani et al. (2018). Ramezankhani et al demonstrated the downregulation of pluripotency markers such as Oct 4, along-with an upregulation of cancer stemness/aggressiveness in the TNBC cell line MDAMB231 when treated with Vitamin C + miR 302/367 (mi RNA that have been established to reprogram a cell into a pluripotent stem cell). The dose of Vitamin C used by Ramezankhani et al is 100 ug/ ml that corresponds to 0.56 millimolar.
Hence, the above two literature have contradictory findings in which one is stating the upregulation of pluripotency markers in breast CSCs and the other one is stating downregulation. Accordingly, one needs to check the differentiation/quiescent status of the breast CSCs, especially in case of TNBCs. Moreover, the threshold concentration of Vitamin C that can cause the upregulation versus downregulation of pluripotency and/or stemness markers. In fact, our own work has shown an opposing effects-proliferation versus apoptosis of colon cancer stem cells when treated with low (5-25 micromolar) versus high (100-500 micromolar) concentrations of Vitamin C respectively (Sen et al. 2017).
Taken together, it all boils down to how one can assimilate the information, the published one, as well as, their own data to reach the final conclusion.
References:
- Akrap, N., Andersson, D., Bom, E., Gregersson, P., Ståhlberg, A., & Landberg, G. (2016). Identification of distinct breast cancer stem cell populations based on single-cell analyses of functionally enriched stem and progenitor pools. Stem cell reports, 6(1), 121-136.
- Ramezankhani, B., Taha, M. F., & Javeri, A. (2018). Vitamin C counteracts miR‐302/367‐induced reprogramming of human breast cancer cells and restores their invasive and proliferative capacity. Journal of Cellular Physiology.DOI: 10.1002/jcp.27081
- Sen, U., Shenoy P, S., & Bose, B. (2017). Opposing effects of low versus high concentrations of water soluble vitamins/dietary ingredients Vitamin C and niacin on colon cancer stem cells (CSCs). Cell biology international, 41(10), 1127-1145.
