Colorectal cancer is the number one cancer in Singapore and the third most commonly occurring cancer in the world. It is characterised by the uncontrolled growth of cells in the epithelial tissue of the large intestine. Like other cancers, treatment options for colorectal cancer haven't changed much over the years and is still restricted to chemotherapy, radiotherapy and surgery.
In a news release issued on Monday (Nov 9), NTU said that a team led by Professor Teoh Swee Hin harnessed the Clostridium sporogenes (C. sporogenes) bacteria in its dead form, and its secretions, to effectively destroy colon tumour cells.
In a 72-hour experiment, the inactive bacteria were able to reduce the growth of colon tumour cells by 74 per cent. The team tested the secretions harvested from a live bacteria culture and these secretions reduced the growth of colon tumour cells by as much as 83 per cent.
NTU said that traditional cancer treatments like chemotherapy and radiotherapy do not work well in the colon due to reduced blood flow and lack of oxygen and nutrient flow. It said that these therapies use oxygen molecules to damage the DNA of cancer cells and rely on blood flow to transport therapeutic drugs to the tumour. The team conducted the experiments in artificially-created environments resembling the inside of a human body, rather than on a flat surface in a petri-dish.
"In contrast, the NTU team showed that dead C. sporogenes bacteria can kill tumour cells in an oxygen-starved tumour microenvironment," said NTU.
"We found that even when the C. sporogenes bacteria is dead, its natural toxicity continues to kill cancer cells, unlike the conventional chemotherapy drugs which need oxygen to work," explained Prof Teoh.
Prof Teoh said that other research groups have experimented with live bacteria to destroy cancer cells, but this treatment posed a risk of infection as live bacteria will grow and proliferate.
"In the NTU study, as the bacteria were already killed by heat, there was no risk of the bacteria multiplying and causing more harm than the desired dose meant to kill colorectal cancer cells."
Professor James Best, Dean of NTU's Lee Kong Chian School of Medicine, said: "This is a significant discovery that potentially opens a new avenue to tackle this very common cancer, which is difficult to treat after it has spread. While it is early days, this exciting research finding provides hope of a new treatment option for millions of people affected by bowel cancer each year."
This study was published in the journal Scientific Reports in October: https://www.nature.com/articles/srep15681