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Biology Corner: Brazilian wasp venom kills cancer cells

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Biology Corner CER
September 1, 2015 in Chemistry / Biochemistry Brazilian social wasp Polybia paulista. Credit: Prof. Mario Palma/Sao Paulo State University

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The social wasp Polybia paulista protects itself against predators by producing venom known to contain a powerful cancer-fighting ingredient. A study reveals exactly how the venom's toxin—called MP1 (Polybia-MP1)—selectively kills cancer cells without harming normal cells. MP1 interacts with lipids that are abnormally distributed on the surface of cancer cells, creating gaping holes that allow molecules crucial for cell function to leak out.

MP1 acts against microbial pathogens by disrupting the bacterial cell membrane. The antimicrobial peptide shows promise for protecting humans from cancer; it can inhibit the growth of prostate and bladder cancer cells. However, until now, it was not clear how MP1 selectively destroys cancer cells without harming normal cells.

Researchers suspected that the reason might have something to do with the unique properties of cancer cell membranes. In healthy cell membranes, phospholipids called phosphatidylserine (PS) and phosphatidylethanolamine (PE) are located in the inner membrane leaflet facing the inside of the cell. But in cancer cells, PS and PE are embedded in the outer membrane leaflet facing the cell surroundings.

The researchers tested their theory by creating model membranes, some of which contained PE and/or PS, and exposing them to MP1. The presence of PS increased the binding of MP1 to the membrane and the presence of PE enhanced MP1's ability to quickly disrupt the membrane, increasing the size of holes. These large pores allowed molecules like RNA and proteins to leak out of the cell.

In future studies, the researchers plan to alter MP1's amino acid sequence to examine how the peptide's structure relates to its function and further improve the peptide's selectivity and potency for clinical purposes. "Understanding the mechanism of action of this peptide will help in translational studies to further assess the potential for this peptide to be used in medicine," Beales says. "As it has been shown to be selective to cancer cells and non-toxic to normal cells in the lab, this peptide has the potential to be safe, but further work would be required to prove that."
1

What it the Evidence? Select all that apply

MP1 acts against microbial pathogens by disrupting the bacterial cell membrane.
The antimicrobial peptide shows promise for protecting humans from cancer; it can inhibit the growth of prostate and bladder cancer cells.
However, until now, it was not clear how MP1 selectively destroys cancer cells without harming normal cells.
Researchers suspected that the reason might have something to do with the unique properties of cancer cell membranes.
In healthy cell membranes, phospholipids called phosphatidylserine (PS) and phosphatidylethanolamine (PE) are located in the inner membrane leaflet facing the inside of the cell.
But in cancer cells, PS and PE are embedded in the outer membrane leaflet facing the cell surroundings.
The researchers tested their theory by creating model membranes, some of which contained PE and/or PS, and exposing them to MP1.
The presence of PS increased the binding of MP1 to the membrane and the presence of PE enhanced MP1's ability to quickly disrupt the membrane, increasing the size of holes.
These large pores allowed molecules like RNA and proteins to leak out of the cell.
In future studies, the researchers plan to alter MP1's amino acid sequence to examine how the peptide's structure relates to its function and further improve the peptide's selectivity and potency for clinical purposes. "Understanding the mechanism of action of this peptide will help in translational studies to further assess the potential for this peptide to be used in medicine," Beales says. "As it has been shown to be selective to cancer cells and non-toxic to normal cells in the lab, this peptide has the potential to be safe, but further work would be required to prove that."
1

What it the Reasoning behind the research? Select all that apply

MP1 acts against microbial pathogens by disrupting the bacterial cell membrane.
The antimicrobial peptide shows promise for protecting humans from cancer; it can inhibit the growth of prostate and bladder cancer cells.
However, until now, it was not clear how MP1 selectively destroys cancer cells without harming normal cells.
Researchers suspected that the reason might have something to do with the unique properties of cancer cell membranes.
In healthy cell membranes, phospholipids called phosphatidylserine (PS) and phosphatidylethanolamine (PE) are located in the inner membrane leaflet facing the inside of the cell.
But in cancer cells, PS and PE are embedded in the outer membrane leaflet facing the cell surroundings.
The researchers tested their theory by creating model membranes, some of which contained PE and/or PS, and exposing them to MP1.
The presence of PS increased the binding of MP1 to the membrane and the presence of PE enhanced MP1's ability to quickly disrupt the membrane, increasing the size of holes.
These large pores allowed molecules like RNA and proteins to leak out of the cell.
In future studies, the researchers plan to alter MP1's amino acid sequence to examine how the peptide's structure relates to its function and further improve the peptide's selectivity and potency for clinical purposes. "Understanding the mechanism of action of this peptide will help in translational studies to further assess the potential for this peptide to be used in medicine," Beales says. "As it has been shown to be selective to cancer cells and non-toxic to normal cells in the lab, this peptide has the potential to be safe, but further work would be required to prove that."
9

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