Friday February 26 2010
The exotic bitter melon is unusual in look and taste
An extract of bitter melon “can block breast cancer” reported BBC News. Its website reported on research that suggests it “turns off signals telling the breast cancer cells to divide, and switched on signals encouraging them to commit suicide”.
The study underlying this news story looked at the effect of an extract of the exotic bitter melon fruit on breast cancer cells that were grown in culture. It found that the extract halted division of the cells and triggered a type of ‘cell suicide’ where the cells make proteins that induce their own death.
However, this was very preliminary research and its direct relevance to humans is very limited without much more research. The research also failed to identify the key ingredients in bitter melon that caused these effects on cells. Overall, this research has provided no evidence to suggest that eating bitter melon or bitter melon extract can prevent or treat breast cancer.
Where did the story come from?
This US research was carried out by Dr Ratna Ray and colleagues from Saint Louis University and the University of Hawaii. The study was financially supported by funding from Saint Louis University. The study was published in the peer-reviewed journal, Cancer Research.
This research was covered well by the BBC, which emphasised the very preliminary nature of this research. The Independent also covered the story concisely but did not specify that this work was done using cultured cells in a laboratory. Its statement that “bitter melon extract significantly induced death in breast cancer cells and decreased their growth and spread” could be misinterpreted as referring to the tumour cells of a cancer patient.
What kind of research was this?
This was a laboratory study looking at how a concentrated extract of bitter melon affected human breast cancer cells in culture. It also compared how exposure to bitter melon extract (BME) affected non-cancerous human cells.
The researchers report that extract of bitter melon (Momordica charantia) has sugar- and fat-lowering properties.
What did the research involve?
The researchers used two types of human breast cancer cell lines, MCF-7 and MDA-MB-231. They also examined a non-cancerous human breast cell line known as HMEC cells.
To prepare the BME the researchers liquidised bitter melons in a household juicer and centrifuged the contents to remove any solids, leaving liquid BME.
The researchers added the extract to the cells in increasing concentrations and measured cell death. They did this by either looking at whether the membrane surrounding the cell was intact or by looking for markers of a type of programmed cell death called apoptosis. In apoptosis a stimulus will trigger a cell to switch on genes that will cause it to die.
What were the basic results?
When cell death was measured by looking at cell membrane integrity, 80% of the MCF-7 and MDA-MB-231 cancer cells had died within 48 hours of treatment with two parts BME to 100 parts cell culture medium (the liquid that covers cells in culture and provides their nutrients). At the same BME concentration the non-cancerous HMEC cells did not die, even after five days.
Programmed cell death involves a combination of proteins that can promote or prevent cell death. When exposed to BME the MCF-7 and MDA-MB-231 cancer cells had raised levels in the protein, catalase, that is produced during programmed cell death. The cancer cells also showed reduced levels of three proteins that prevent programmed cell death (survivin, XIAP and claspin).
Cancer cells divide frequently, causing tumours to grow. The researchers found that cell division was partially halted when treated with BME for 24 hours. The amount of two proteins involved in cell division - cyclin B1 and cyclin D1 - was also lowered.
How did the researchers interpret the results?
The researchers suggest that BME inhibits cell growth and causes breast cancer cells to die through programmed cell death. They suggest that BME affects several proteins involved in controlling cell division and cell death, and that these signalling pathways may have a combined effect to induce breast cancer cell death. They further add that BME “can be used as a dietary supplement for prevention of breast cancer”.
This was a basic laboratory study that found that putting bitter melon extract on breast cancer cells in culture caused cell death. As this study was conducted on cells in the laboratory there is limited relevance to humans without further research. It does not provide sufficient evidence to suggest that BME supplements or consuming bitter melon can prevent or treat breast cancer.
Cells grown in cell culture can behave very differently to those in the human body. Even in culture, cells’ behaviour can vary depending on the type of nutrient-containing liquid (medium) they are grown in. A limitation of the present study is that the cancerous and non-cancerous cells were grown in different types of medium, which may have affected their response to the BME.
A further limitation of the study is that it did not isolate which chemical or chemicals in BME caused the effects observed. Much more additional research is needed to assess whether chemicals within bitter melon have any potential in breast cancer drug development or any ability to prevent cancer when ingested.