London, June 29 Aussie scientists have developed a new therapy that uses minicells to deliver cancer drugs, in order to prevent resistance in cancer cells.
The researchers are confident that the breakthrough could pave way for cheaper cancer treatments with fewer side effects.
While experimenting on mice, the researchers used minicells to deliver cancer drugs to resistant tumours.
The minicells were made from bacteria and contained pieces of genetic material, known as short interference RNA (siRNA), which knockout or 'silence' the drug-resistant genes of tumours.
After a few days, the researchers injected another dose of minicells filled with chemotherapy drugs, which the tumour was previously resistant to.
Dr Himanshu Brahmbhatt, molecular biologist and joint director of the biotechnology company Engeneic, said that cancer cells have an inbuilt mechanism to develop drug resistance over time.
"(Drug resistance) is one of our biggest killers in terms of cancer therapy," Nature magazine quoted him as saying.
He claimed that silencing the genes of the drug-resistant tumour cell makes the cancers sensitive to the chemotherapy again.
Earlier, it was believed that siRNA could pass through cells membranes due to their size, but Brahmbhatt says that the new study has shown that this isn't necessarily the case.
"Bacterial membranes might be quite different because they have protein channels (in their membrane) through which siRNA's can enter (the minicell)," he said.
The outer surface of the minicell membrane is not only packed with gene silencing siRNA, but is also coated with antibodies, which lock onto (antigen) receptors on the tumour cells.
"The cancer cell then swallows the entire minicell," said Brahmbhatt.
He added that once the minicell is inside the cancer cell, its breaks down and the siRNA or the drug floods the interior of the tumour cell.
"That's why we haven't seen any toxic side effects because this is intra-cellular delivery," he said.
The study has shown that the combined minicell therapy can inhibit the growth of drug-resistant tumour xenographs, artificially manufactured tumours, for up to four months.
The findings appear in the online edition of Nature Biotechnology. (ANI)
