Honey has always been used not only as a food/sweetener but also as a medicine since ancient times. The quality and composition depend on many factors, including the botanical origin, the environmental, processing and storage conditions[1]. The nutritional characteristics and the preventive/therapeutic effect of honey are due to its composition: it contains over 180 different types of compounds including water, carbohydrates, enzymes, amino acids, minerals, vitamins and different phytochemicals[2] . Among the different effects on health, those most studied in the scientific literature are its antibacterial activity[3] and the antioxidant capacity[4]. In recent years the potential anticancer effect of honey, in several tumor cell lines, has also been a reason of study[5]. Among different types of honey, Manuka, has shown a high anticancer effect, especially in colon cancer cells (LoVo and HCT-116)[6,7] while it is little known on its effect in cancer stem cells' (CSCs; a rare population of cells within the tumor mass that seem to be responsible for the tumor onset) chemoresistance and the presence of relapse [8]. Therefore, the effect of Manuka honey on CSCs-like was evaluated. In general, CSCs-like were enriched from the monolayer population of HCT-116 through the in vitro sphere forming assay[9]. This honey was able to modify the morphological parameters of the spheroids, reducing the size and volume of the entire culture. The treatment of CSCs-like enriched colonospheres with Manuka honey also led to an intracellular accumulation of ROS and induction of apoptosis. Furthermore, through real-time PCR, down-regulation of ABCG2 gene expression (one of the efflux pumps closely associated with the chemoresistance phenotype) was observed.
References
- DOI: 10.1016/j.lwt.2017.08.079
- DOI: 10.3390/molecules23092322
- DOI: 10.1155/2019/2464507
- DOI: 10.1016/j.jff.2016.05.008
- DOI: 10.1016/j.clnu.2018.12.019
- DOI: 10.1039/c8fo00164b
- DOI: 10.1039/c8fo00165k
- DOI: 10.1016/j.phrs.2018.08.006
- DOI: 10.18632/oncotarget.6261
Some questions: why do you measured ROS after 48h? This time is too long to measure reactive species generation considering the kinetic of these molecules. ROS generation after 48 hr in your sytem could be an artifact or a consequence, the effect of treament not the cause of death.
The second consideration is the concentration of your extract: 75 mg/ml or microg/ml?
In my experience when you use so" huge quantity" of an extract in cell culture medium, there could be many experimental artifacts, such as the generation of ROS with some components in cell culture medium that could explain cell death. So this is an aspecific effect.
What do you think?
Maria Russo
maria.russo@isa.cnr.it
Thank you for your interest and for your comments.
I proceed to measure ROS after 48 h because I want to understand what happened when the formed spheroids start to have some morphological change. This change in morphology it wasn't possible to see before 48 h. It is interesting your comments and maybe it is possible to make experiment for check if, also there isn't change in morphological features of spheroids, there are some effects in ROS generation, also for exemple after 24 hours. In the experiments I used 50 and 75 mg/mL. Before to decide this concentration I tested more or less the same concentrations that in our previous works we used for monolayer culture in the same cell lines, like 10-25 mg/mL, but they don't affect shape or dimensions of spheroids. In fact in 3D culture the drug penetration is really different from 2D culture. I proceed moreover to test the used concentration of Manuka honey also on healty human colon fibroblast (data not shown in this abstract) and they results to be no-cytotoxic for these cells. It is a preliminary work, also because in scientific literature there isn't nothing about CSCs grown like spheroids and the effect on these by honey.
I hope I was clear and answered correctly to what you asked. If you have any other curiosities, I'm available.
Danila Cianciosi
