Anticancer activity of stingless bee propolis on human cancer cells

Abstract

The present research work entitled “Anticancer activity of stingless bee propolis on human cancer cell line” was carried out in the Department of Plant Biotechnology, College of Agriculture, Vellayani, Thiruvananthapuram and Department of Genomic Science, Central University of Kerala during 2020-2021, with the objective to study the effect of propolis collected from two different genera of Stingless bees, viz., Lisotrigona sp. and Tetragonula spp. on human cancer cell line- A549. Crude propolis samples were collected from the nest of three species of stingless bees Lisotrigona sp. (Kollam), Tetragonula calophyllae (Thiruvananthapuram) and Tetragonula travancorica (Thiruvananthapuram). Propolis samples were macerated at room temperature and extracted with 95% ethanol. MTT assay was performed and IC-50 values were calculated in-order to determine the influence of propolis on the proliferation of human cancer cell line. Five different concentrations of propolis, viz., 150µg/ml, 300µg/ml, 450µg/ml, 600µg/ml and 900µg/ml respectively, were added to A549 cells for a period of 24 hrs. Cells treated with the propolis extracted from Lisotrigona sp, T. calophyllae and T. travancorica obtained IC50 values of 485.822 ug/ml, 236.6095 ug/ml and 294.223 ug/ml respectively. It was observed that, propolis treatment had an inhibitory effect on A549 cells after 24 hrs treatment in relative to the control. When the cells were treated with the right concentration of propolis, marked difference in their morphology was observed. The cells appeared to shrink and were floating.Quality and quantity of the samples were analyzed through nanodrop, which gave an absorbance value of 1.8 to 2.0 for all the samples. The concentration of the samples observed was between 30-200 ngµl-1 . The RNA samples were then subjected to cDNA conversion (iScriptTM cDNA Synthesis Kit). The cDNA of control and treated samples were then subjected qRT PCR. The real-time quantitative PCR (qPCR) was performed with the Applied Biosystems PCR system in a total volume of 10 µl and expression of different genes was studied. Gene expression analysis revealed that propolis taken from Lisotrigona sp. treated VIM was downregulated and it indicates that the cell migration and EMT formation are suppressed. propolis taken from T. calophyllae downregulated the expression of NODAL and it shows the inhibition of EMT formation. propolis taken from Lisotrigona sp. showed upregulation of CDX2 expression indicating that propolis from Lisotrigona sp. inhibits cell proliferation. 59 To conclude, the result of the study proved that, propolis obtained from the stingless bee Lisotrigona sp. showed more inhibitory effect on cancer cell line- A549 compared to Tetragonula spp.