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Prostate cancer is the most common form of cancer and one of the most common causes of death among men. Suppression of the immune system plays a major role here. Therefore researchers Willem Stoorvogel and Marianne Boes want to develop a vaccine that reverses that suppression. In 2015 they received a Seed Money Grant to start the research.

The immune system is an important defence mechanism against the development of cancer. “Everyone makes tumour cells continuously, perhaps dozens per day,” says Marianne Boes, Associate Professor of Immunology at the Wilhelmina Children's Hospital in Utrecht. “However, the vast majority is tackled by our immune system, preventing early cancer development”

Sperm suppresses rejection response

Therein lies the problem in the case of prostate cancer, according to the research duo. The immune system seems to fall short. “This has to do with reproduction,” says Willem Stoorvogel, Professor of Biochemistry and Cell Biology at the University of Utrecht. “Sperm is a foreign substance to the woman’s body, which would normally be rejected.”

Nature has however found a way to intervene. “There are small membrane vesicles measuring 100 nanometres in semen; so-called prostasomes that can dampen the female immune system, allowing fertilisation to take place. We suspect that these prostasomes also suppress male immunity against prostate tumour cells, which can lead to cancer.”

Applications

The duo wants to see whether this could be a leverage point in the prevention of prostate cancer and received a Seed Money Grant to kick off this research in January 2015. “We first want to see whether our hypothesis is correct that prostasomes suppress certain immune cells,” explains Boes. “And we want to change the composition of prostasomes in such a way that they no longer suppress the immune system, but rather strengthen it. In time, we want to develop a vaccine for men with prostate cancer.”

“The good thing is that we have Veterinary and Human Medicine so close together in Utrecht,” says Stoorvogel. “Prostate cancer also occurs regularly in dogs, so down the road this is where we can begin testing. If it works in dogs, the step to humans is a lot closer.” But first the team will first work on a proof of concept which they can establish thanks to this grant.

“We could also use prostasomes as a biomarker, to indicate the presence of cancer,” Boes continues. “PSA measurements are not very reliable; PSA levels in blood do not always correlate with cancer. Perhaps our research will uncover a reliable alternative.”

This publication is closely related to Utrecht University’s strategic research theme Life Sciences, under the sub-theme Public Health.

Text: Roy Keeris

Second call Seed Money

In 2015 four research projects were approved in the second call Seed Money Life Sciences. The researchers who received a grant in the second call are:

• Antimicrobial drugs optimization by decoration with non-natural sugar variants - Marc Wösten (Veterinary Medicine) / Roland Pieters (Science)
  > Read more in the article Sugars give antibiotics a second chance
   
• Modified autologous prostasomes as a vaccine for prostate cancer - Willem Stoorvogel (Veterinary Medicine) / Marianne Boes (Medicine)
   
• Human lung organoids: a novel model to understand respiratory syncytial virus Bronchiolotis - Louis Bont (Medicine) / Norman Sachs (Hubrecht Institute)
  > Read more in the article Growing ‘mini-lungs’ in the fight against child mortality
   
• Metabolic Requirements for genome integrity in adult stem cells - Boudewijn Burgering (Medicine) / Ruben van Boxtel (Hubrecht Institute)
  > Read more in the article Improving the quality of stem cells for new organs