2 Compounds in Coffee Seen to Slow Growth of Prostate Cancer in Early Study

Two compounds found in coffee might be able to slow the growth and migration of prostate cancers, a pilot study conducted in drug-resistant cancer cells and a mouse model report.

As such, two possible therapeutic candidates for drug-resistant prostate cancers may have been identified in this work, which also helps in explaining why findings in some studies show regular coffee drinkers with lower prostate cancer risks.

The compounds, kahweol acetate and cafestol, were seen, in a dose-dependent manner, to slow the progression of prostate tumors that are resistant to standard therapy in mice. Researchers in Japan plan to continue with this line of study.

The study, “Coffee diterpenes kahweol acetate and cafestol synergistically inhibit the proliferation and migration of prostate cancer cells,” was published in The Prostate and presented at the recent 2019 Annual European Association of Urology (EAU) Congress, held in Barcelona.

Some evidence suggests a link between drinking certain types of coffee and a lower risk of some cancers, including prostate cancer. A grouped analysis of studies, which included 864,012 subjects, estimated that regular coffee drinkers were 11% less likely to develop prostate cancer than those who rarely or never drank it.

But coffee is made of a complex mixture of more than 1,000 compounds, and we know little about which are responsible for its potential anti-cancer effects.

This gap sparked the attention of a team of scientists at Kanazawa University Graduate School of Medical Science.

They investigated in more detail the anti-cancer activity of six coffee compounds: kahweol acetate, cafestol, caffeine, caffeic acid, chlorogenic acid, and trigonelline hydrochloride.

Several human prostate cancer cell lines, cultured in the lab, were exposed to each compound, and their ability to inhibit cell proliferation and migration was measured.

Cell migration is often addressed in cancer studies because the movement of tumor cells into surrounding tissues and blood vessels is an initial step in tumor spread (metastasis).

Some of these cancer cell lines were drug-resistant and mimicked castration-resistant prostate cancer (CRPC), including one that does not respond to common chemotherapy treatments such as Jevtana (cabazitaxel), by Sanofi Genzyme.

From the six tested compounds, only two – kahweol acetate and cafestol – proved to have anti-proliferative and anti-migration effects against cancer cells.

These two compounds are naturally found in Arabica coffee, but the brewing process affects whether they remain in coffee or not. Espresso or Turkish coffee retain the two, whereas filtered coffee takes them off.

Researchers then tested both compounds on human prostate cancer cells transplanted to mice, a so-called xenograft model. They compared tumor progression in mice treated with kahweol acetate and cafestol, alone or in combination, to its progression in untreated mice.

Each agent alone slowed the growth of cancer cells, but a combination of the two seemed best at slowing tumor progression in the animals. After 11 days, the tumors in the untreated group were around three and a half times larger (342% growth), while those in mice given both kahweol acetate and cafestol were slightly one and a half times larger (167% growth) than at the start.

“It is important to keep these findings in perspective. This is a pilot study, so this work shows that the use of these compounds is scientifically feasible, but needs further investigation; it does not mean that the findings can yet be applied to humans,” Hiroaki Iwamoto, a researcher at the Kanazawa University school and the study’s leader, said in a EAU press release.

“These are promising findings, but they should not make people change their coffee consumption,” added Atsushi Mizokami, also a professor there and senior study author.

Coffee can have health benefits but also can be a cause of problems like rising blood pressure and restlessness, and researchers need to learn more about mechanisms behind these findings before they can think about clinical applications, he said.

What the study shows “is that these compounds appear to have an effect on drug resistant prostate cancer cells in the right circumstances, and that they too need further investigation. We are currently considering how we might test these findings in a larger sample, and then in humans,” Iwamoto added.