Biological efects of South African plant extracts on RBBp6 as anti-cancer therapy in lung cancer

摘要

Plant extracts contain compounds, which are anti-cancer agents, that possess anti-tumour activity. Most of these compounds are known to hinder the activation of cell cycle and induce cell death. During various types of stress in a normal cell, p53 and Rb enhance programmed cell death to prevent human tumour cells from forming. However, programmed cell death is not enhanced in the presence of RBBp6 or Mdm2. Thus, cell cycle will be enhanced, resulting to abnormal cells proliferating and causing cancerous cells or tumours. RBBp6 is a p53-associated cellular protein and retinoblastoma binding protein containing a conserved N-terminal ring-finger domain, which takes part in p53 degradation. RBBp6 is highly expressed in lung cancer and may be a promising target for treating cancer. The aim is to use plant extracts to regulate the expression of RBBp6, switching it off from being pro-carcinogenic to becoming an anti-carcinogenic protein in lung cancer cells. Two cancer cell lines (Lsqr1 and A549) were cultured and treated with Euphorbia mauritanica and Kedrostis hirtella extracts. A MTT assay was used to determine 50% cell death, which was induced by 5 μg/ml and 10 μg/ml of the Euphorbia mauritanica and Kedrostis hirtella extracts after 22 hrs and 24 hrs, respectively. Molecular analysis using gel DNA fragmentation showed smeared DNA due to necrosis and a fragmented DNA induced by apoptosis. The quantity of cells undergoing apoptosis and necrosis was measured by flow cytometry, which showed a higher percentage of necrotic cells compared to apoptotic cells. Real-time PCR was used in order to analyse the RBBp6 expression in lung cancer cells treated with the plant extract. The results of the present study showed no change or an insignificant decreased in the expression of RBBp6 in lung cancer cells treated with the extracts. Therefore, plant extracts used in this research have no effect on RBBp6 as anti-cancer therapy.