Daily Bulletin

The Conversation

  • Written by Thomas Williams, Research Fellow in Synthetic Biology, Macquarie University

Scientists are successfully experimenting with a creative approach to treat cancer by genetically programming bacteria to invade tumours and destroy cells from within.

In a study published this week in the journal Nature, authors showed programmed bacteria given to mice with aggressive liver cancer were able to destroy themselves while releasing a drug into the tumour at the same time.

Researchers exploited the tumours' poor blood supply, and consequently poor oxygen levels, by using strains of Salmonella enterica (S. enterica) – a bacterial species that can survive when no oxygen is present. The bacteria was drawn to the low-oxygen environment inside the tumour and provided targeted destruction of diseased cells.

Differentiating cancer cells from normal cells is critical to reduce the often awful side-effects of chemotherapy that come about because healthy cells are affected alongside cancerous ones.

The study’s authors showed when this treatment was provided alongside chemotherapy in mice, tumours shrank significantly within 18 days before regrowing.

The use of the engineered bacteria alongside chemotherapy was significantly more effective than chemotherapy alone, but substantial development of this technology is required before it can be employed in humans.

Bacteria and cancer

Traditional cancer treatments such as chemotherapy and surgery have made great strides towards better patient outcomes. Yet we are increasingly recognising the need for new ideas and technologies if we want to truly defeat cancer.

Bacteria are single-celled microorganisms that live everywhere that life exists on earth, including our own bodies. Their cells are around ten times smaller than our own, which means if a single engineered bacterial cell were to attack a tumour, it would have little or no effect.

Therefore, the study’s authors programmed bacteria to effectively count themselves and only attack the tumour when they had the numbers to be effective. This was done using a naturally occurring system called “quorum sensing” where individual cells emit a signalling molecule into the environment.

When there are few other cells in the near vicinity, the signalling molecules exist at a low concentration. As bacterial cells grow and divide, they make more and more of the signalling molecule until it reaches a critical concentration at which every cell in the population simultaneously switches on groups of genes.

In this case, the bacteria turn on genes that result in a self-destruct program. Nearly all the bacterial cells in the population rupture to release an anti-cancer drug called Haemolysin E into the tumour. The drug kills cancer cells by puncturing their membranes and therefore making holes for their inner components to leak out of.

The few bacterial cells that don’t execute the self-destruct function grow again to repeat the process so cycles of tumour attacks are repeated.

Synthetic biology

Bacteria were suggested for use in cancer treatment as early as 1891, but without the tools of synthetic biology this approach would be impossible. Synthetic biologists combine principles from engineering, molecular biology and computer science to reprogram living organisms to perform useful functions.

For example, synthetic biology is being used to engineer microorganisms to produce bio-fuels and chemicals from renewable resources, produce pharmaceuticals and novel drugs and even execute computational tasks for a variety of applications.

Bacteria have evolved to be efficient at replication, and performing functions desired by humans, such as coordinated tumour destruction, is not normally part of their behavioural repertoire. But synthetic biology provides the means to encode entirely new functions in microorganisms with the fine level of control demanded by modern engineering disciplines.

Of course several steps need to be taken before the treatment method shown in the Nature study can become a reality. The efficiency of the engineered bacterial cells' tumour-destroying abilities would need to be dramatically improved to prevent regrowth.

Another consideration is that at the moment there is no mechanism that would prevent the bacteria from evolving to live outside the low-oxygen tumour environment and attacking other parts of the body.

Although this scenario is unlikely because the bacteria would have to compete with the trillions of naturally occurring microorganisms that thrive in the human body, issues like this would need to be addressed before proceeding to further trials.

On the bright side, synthetic biologists are more than capable of engineering the safety mechanisms that would be required to advance this technology to the clinic.

Authors: Thomas Williams, Research Fellow in Synthetic Biology, Macquarie University

Read more http://theconversation.com/new-cancer-treatment-scientists-have-programmed-bacteria-to-kill-cancer-cells-in-mice-62831

Writers Wanted

Racing 2-year-old horses is lucrative, but is it worth the risks?


How to Sanitize Cloth Masks Properly


The Conversation


Ray Hadley's interview with Scott Morrison

RAY HADLEY: Prime Minister, good morning.    PRIME MINISTER: G’day Ray.   HADLEY: I was just referring to this story from the Courier Mail, which you’ve probably caught up with today about t...

Ray Hadley & Scott Morrison - avatar Ray Hadley & Scott Morrison

Prime Minister's Remarks to Joint Party Room

PRIME MINISTER: Well, it is great to be back in the party room, the joint party room. It’s great to have everybody back here. It’s great to officially welcome Garth who joins us. Welcome, Garth...

Scott Morrison - avatar Scott Morrison

Prime Minister Interview with Ben Fordham, 2GB

BEN FORDHAM: Scott Morrison, good morning to you.    PRIME MINISTER: Good morning, Ben. How are you?    FORDHAM: Good. How many days have you got to go?   PRIME MINISTER: I've got another we...

Scott Morrison - avatar Scott Morrison

Business News

Tips to find the best plastic manufacturing supplier for your needs

Plastics are very much an important part of all of our lives, but they’re particularly valuable to a wide variety of industries that rely on their production for their operations. The industries, ...

News Co - avatar News Co

7 foolproof tips for bidding successfully at a property auction

Auctions can be beneficial for prospective buyers, as they are transparent and fair. If you reach the limit you are willing to pay, you can simply walk away. Another benefit of an auction is tha...

Dominique Grubisa - avatar Dominique Grubisa

Getting Ready to Code? These Popular and Easy Programming Languages Can Get You Started

According to HOLP (History Encyclopedia of Programing Languages), there are more than 8,000 programming languages, some dating as far back as the 18th century. Although there might be as many pr...

News Co - avatar News Co

News Co Media Group

Content & Technology Connecting Global Audiences

More Information - Less Opinion