Globally, liver cancer is the second leading cause of death due to malignancy. Alcoholic or nonalcoholic fatty liver, chronic viral hepatitis B or C, which are increasing worldwide year by year, are at high risk for liver cancer
Some people envision how great it would be to have a vaccine specifically for liver cancer that could be injected to prevent the development of liver cancer!
A recent animal study published in Cell Reports found that polyinosinic acid-polycytidylic acid (pIC) was effective in inhibiting primary liver cancer in mice.
What if a liver cancer vaccine is really possible? Let’s take a look at how the study was conducted.
How was this study conducted?
The basic idea of the study was to inject the chemical carcinogen diethylnitrosamine (DEN) to cause liver cancer in experimental mice.
The effect of intraperitoneal injection of a double-stranded RNA, polyinosinic-polycytidylic acid (pIC), on hepatocellular carcinogenesis and progression in diethylnitrosamine-induced mice was examined at various time points in the study, primarily before hepatocarcinogenesis.
All experimental mice were injected with DEN on day 15 of life, and the induced hepatocellular carcinoma was expected to appear at 5 months of age. The same dose of pIC was administered at any time point on day 9, 1 month, 3 months, and 5 months of life.
The effect of DEN on the hepatocellular carcinoma in the mice was estimated to occur at 5 months.
Mice were executed at 8 months, and livers were taken to measure the number, weight, and size of hepatocellular carcinomas.
What are the major findings of this study?
At month 8, the researchers executed all the mice and removed the livers to see how the tumors were growing.
- Mice injected with pIC at 9 days and 1 month had a significant reduction in the number of liver cancers, the size of the liver cancers, and the proportion of the whole liver to their body weight;
- Mice injected with pIC at 3 months of age had a significant reduction in the number and size of liver cancers, but not as a proportion of body weight;
- Mice injected with pIC at 5 months of age had even less cancer-inhibiting effect.
This shows that the earlier pIC is injected, the more pronounced the inhibitory effect on hepatocellular carcinoma in mice, and by the time hepatocellular carcinoma has begun to appear (at 5 months), the effect of pIC injection is too weak.
This means that pIC has a preventive effect against hepatocellular carcinoma, but is not a good deterrent to hepatocellular carcinoma growth if it is already present.
Researchers speculate that the cancer-preventing effects of pIC are related to enhancing the body’s own innate immune system. pIC is able to remove damaged, tumor-turning hepatocytes from the body by reprogramming macrophages and activating immune cells such as natural killer cells, prompting them to turn into apoptotic cells.
What is the significance of this study?
The results of this study suggest that pIC can effectively inhibit hepatocellular carcinogenesis, especially before liver cancer cells form, suggesting that pIC may be a breakthrough in the development of a liver cancer vaccine.
While pIC did not have a significant inhibitory effect on established tumor cells, this does not preclude the use of pIC in future studies of patients with liver cancer, perhaps in combination with other chemotherapeutic agents to enhance efficacy.
While there is still a long way to go from animal studies, to clinical studies, to drugs on the market, this research on pIC brings a glimmer of hope to a large number of people at high risk for liver cancer, making the future even more exciting!