The apoptosis inducing effects of Sutherlandia spp. extracts on an oesophageal cancer cell line

• Published in: Journal of ethnopharmacology 2011-10, Vol.137 (3), p.1250-1260
• Main Authors: Skerman, Nicola B., Joubert, Annie M., Cronjé, Marianne J.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - metabolism; Amino Acid Chloromethyl Ketones - pharmacology; Antineoplastic Agents, Phytogenic - isolation & purification; Antineoplastic Agents, Phytogenic - pharmacology; Apoptosis; Apoptosis - drug effects; Cancer bush; Caspase 3 - metabolism; Caspase 7 - metabolism; Caspase Inhibitors; Cell Line, Tumor; Cell Shape - drug effects; Cell Survival - drug effects; Cysteine Proteinase Inhibitors - pharmacology; Cytochromes c - metabolism; Dose-Response Relationship, Drug; Esophageal Neoplasms - metabolism; Esophageal Neoplasms - pathology; Fabaceae - chemistry; Flow Cytometry; Humans; Leukocytes, Mononuclear - drug effects; Leukocytes, Mononuclear - pathology; Oesophageal cancer; Phosphatidylserines - metabolism; Plant Extracts - isolation & purification; Plant Extracts - pharmacology; Plants, Medicinal; Protein Transport; Spectrometry, Fluorescence; Sutherlandia frutescens; Time Factors
• ISSN: 0378-8741; 1872-7573
• DOI: 10.1016/j.jep.2011.07.054

Oesophageal cancer is the ninth most common cancer in the world and the second most common cancer among South African men. It also has one of the lowest possibilities of cure, with the 5-year survival rate estimated to be only 10% overall. Sutherlandia frutescens, or the “cancer bush”, is a medicinal plant indigenous to southern Africa that is believed to have anti-cancer and anti-proliferative properties. The aim of this study was to investigate the potential apoptosis-inducing effects of two S. frutescens extracts and one Sutherlandia tomentosa extract on the SNO oesophageal cancer cell line. Cell viability and morphology of SNO cells were evaluated following exposure to the extracts. Apoptotic markers including cytochrome c translocation and phosphatidylserine externalisation were quantified by flow cytometry. The activity of caspases 3 and 7 was evaluated with spectrofluorometry. Apoptosis was evaluated in the presence of the pan-caspase inhibitor, Z-VAD-fmk. The effect of the extracts was compared to non-cancerous peripheral blood mononuclear cells (PBMCs). Time– and dose–response studies were conducted to establish treatment conditions of 2.5 and 5mg/ml of crude plant extracts. Microscopy studies revealed that S. frutescens- and S. tomentosa-treated SNO cells had morphological features characteristic of apoptosis. Annexin V/propidium iodide flow cytometry confirmed that the extracts do, in fact, induce apoptosis in the SNO cells. Caspase inhibition studies seem to indicate that extracts A (S. frutescens (L.) R. Br. subsp. microphylla from Colesberg), B (S. frutescens (L.) R. Br. subsp. microphylla from Platvlei) and C (S. tomentosa Eckl. & Zeyh from Stil Bay) are able to induce caspase-dependent as well as -independent cell death. The S. frutescens and S. tomentosa extracts were found to be more cytotoxic to cancerous SNO cells when compared to the PBMCs. S. frutescens and S. tomentosa extracts show promise as apoptosis-inducing anti-cancer agents.