African cobra venom proteins show promise as cancer cell membrane disruptors

Researchers have long suspected that snake venom contains compounds capable of killing cancer cells, yet despite decades of investigation, not a single venom-derived drug has made it through regulatory approval at the FDA or European Medicines Agency. A new study from PLOS Neglected Tropical Diseases offers a detailed look at why some venom proteins show such promise—and how they actually work at the molecular level.

Scientists at multiple institutions isolated and tested four families of proteins extracted from the venom of Naja ashei, an African spitting cobra. They focused on two cancer cell lines: HL-60 cells, derived from leukemia, and SK-N-SH cells, from neuroblastoma. The choice was deliberate. These two cancers represent some of the hardest to treat, with notoriously low survival rates. More importantly, the two cell types have fundamentally different membrane compositions—different ratios of cholesterol, different balances of saturated and unsaturated fatty acids—which meant the researchers could observe whether venom proteins attack cancer membranes in a general way or in ways specific to each cell type.

The team purified three protein families from the cobra venom using chromatography and mass spectrometry: phospholipase A₂ (PLA₂), snake venom metalloproteinases (SVMP), and cysteine-rich secretory proteins (CRISP). They then subjected these proteins to a series of increasingly complex tests. First, they used a technique called Langmuir monolayer analysis to watch how each protein affected artificial lipid membranes that mimicked the composition of real cancer cell membranes. Next, they measured changes in electrical charge on liposome surfaces—synthetic spheres of lipid that model cell membranes. Finally, they exposed actual cancer cells to the venom proteins and measured how much of an enzyme called lactate dehydrogenase leaked out, a direct indicator of membrane damage.

The results showed a clear hierarchy of destructive power. Phospholipase A₂ emerged as the most aggressive membrane disruptor. When applied to neuroblastoma cell membrane models at the highest tested concentration, PLA₂ reduced the membrane's resistance to compression by more than 50 percent—a dramatic loss of structural integrity. The protein also increased the surface area occupied by individual lipid molecules by up to 14.3 percent, suggesting it was forcing the membrane's building blocks apart. SVMP and CRISP caused measurable damage too, but less severe. In the leukemia cell model, the effects were somewhat muted across all three protein families, suggesting that the higher cholesterol content and greater saturation of those membranes made them more resistant to disruption.

When the researchers moved to living cells, the pattern held but with an important twist. In HL-60 leukemia cells, all three protein families triggered detectable membrane damage, with CRISP showing the strongest effect at lower concentrations. But in SK-N-SH neuroblastoma cells, something unexpected happened: the proteins actually reduced enzyme leakage at low concentrations, suggesting they were somehow protecting the membrane rather than destroying it. The researchers note that neuroblastoma cells have a higher proportion of saturated fatty acids, which may create a more rigid, less vulnerable membrane structure. They also point to published evidence that some venom toxins can paradoxically promote cell survival in certain cancer lines, a reminder that the relationship between venom and cancer cells is more nuanced than simple toxicity.

The study's broader significance lies in its systematic mapping of how different venom proteins interact with cancer cell membranes at multiple scales—from the physics of lipid packing to the biochemistry of actual cell damage. The researchers deliberately excluded calcium ions from their model membrane experiments to isolate the structural effects of PLA₂ from its enzymatic effects, revealing that the protein can destabilize membranes through physical disruption alone, independent of its well-known ability to chemically break down lipids. This finding opens new avenues for understanding how venom proteins might be engineered or modified into therapeutic agents.

Yet the path from laboratory discovery to approved drug remains long. The authors note that despite growing evidence of venom toxins' cytotoxic activity against cancer, the translation into clinical medicine has stalled. The work suggests that future therapies inspired by cobra venom might need to be tailored to specific cancer types, since membrane composition—and therefore vulnerability to venom proteins—varies significantly between leukemias, neuroblastomas, and other malignancies. The next phase will likely involve testing whether these proteins can be modified to enhance their selectivity for cancer cells while minimizing damage to healthy tissue, a challenge that has slowed venom-based drug development for years.