Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study shows additional role for abiraterone in blocking tumor growth in CRPC

15.03.2013
As part of an EU-supported IMI-PREDECT consortium (http://www.predect.eu), a Dutch study showed that anti-androgenic properties of the drug abiraterone may provide an additional mechanism of action in blocking tumour growth of castration resistant prostate cancer (CRPC).

The study, which won the first prize for best abstract in oncology at the 28th European Association of Urology (EAU) Congress to be held in Milan from March 15 to 19, demonstrated that although the use of abiraterone can potentially lead to an accumulation of precursor hormones, its anti-androgenic properties may stop precursor hormone-induced androgen receptor (AR) activation.

"Our results show that high concentrations of androgen precursors can drive CRPC growth through direct activation of (overexpressed) AR and not necessarily via the result of (intratumoural) CYP17-metabolism. This suggests that CRPC may not rely solely on de novo androgen synthesis," said lead author Dr. Jan Matthijs Moll of the Erasmus Medical Center, Dept. of Urology in Rotterdam, Netherlands.

Men with castration resistant prostate cancer are a difficult group to treat. Although metastatic prostate cancer may respond well to androgen ablation therapy initially, castration resistance usually develops within three years. Even though circulating testosterone levels are low in these patients, the androgen receptor reactivates, which indicates the AR remains an important target in CRPC.

The Rotterdam-based group has previously demonstrated that conversion of adrenal androgens into testosterone, rather than intratumoural de novo steroidogenesis, is the major source of testosterone in CRPC tumours. [1]

Clinical trials have demonstrated that abiraterone acetate plus prednisone/prednisolone can increase survival in CRPC patients even after chemotherapy [2]. "Blocking androgen synthesis (pregnenolone and progesterone are converted to androgens via CYP17A1 enzymatic activity) in CRPC patients has demonstrated a prolonged survival, but may eventually fail because androgen precursors can activate the AR directly," explained Moll.

In their study, the researchers generated castration resistant clones by long-term culture of VCaP and DuCaP cell lines in steroid-stripped medium (DCC), with or without addition of anti-androgens used in the clinic. Experiments were conducted with a subset of AR-overexpressing CRPC clones to test cell growth and AR-activation in the presence of adrenal androgen precursors, pregnenolone and progesterone or dihydrotestosterone in combinations with increasing levels of abiraterone.

The results showed that high (100 nM) levels of progesterone, but not of pregnenolone, induced cell growth in VCaP and DuCaP CRPC clones, which could not be blocked by low levels of abiraterone (0,1 µM) that are known to fully inhibit CYP17A1 activity (and thus potential subsequent testosterone production).

In a second experiment, the researchers showed that high levels of precursor androgens can directly activate the AR using a model with a fluorescent AR and that ligand-induced AR-translocation from the cytoplasm to the nucleus was slowed down by abiraterone.

"However, high levels of abiraterone (>5 mM) inhibited steroid-induced, but not basal growth of these (CRPC) cells. This finding, together with the observation that DHT-induced growth was inhibited by high levels of abiraterone, indicates that abiraterone can act as an anti-androgen," the researchers wrote.

"We show that abiraterone, a CYP17A1-blocking drug that has recently been approved in the treatment of CRPC, possesses an additional antiandrogenic property and can block androgen precursor-induced AR-activation at higher concentrations than what is needed for CYP17A1 specific inhibition. This may be a good argument to increase abiraterone exposure in the treatment of CRPC," added Moll.

Moll also said that "it is clear that the AR remains the most important target in the treatment of CRPC."

"Blockade of androgen synthesis seems not sufficient to prevent AR activation. New drugs that block AR activation irrespective of the activating ligand may provide new ammunition to last another 'round' for clinicians to treat CRPC," he said. "We believe it is vital to identify which metabolites have the potential to activate the mutated or overexpressed AR present in CRPC, which under normal conditions may not activate the AR. In that perspective, we are currently working together with our partner, Janssen, and other partners within the IMI-PREDECT consortium on developing new model systems for CRPC to further understand its biology and test new potential pathway perturbations that may benefit CRPC patients in the future."

Ivanka Moerkerken | EurekAlert!
Further information:
http://www.uroweb.org

More articles from Health and Medicine:

nachricht Researchers release the brakes on the immune system
18.10.2017 | Rheinische Friedrich-Wilhelms-Universität Bonn

nachricht Norovirus evades immune system by hiding out in rare gut cells
12.10.2017 | University of Pennsylvania School of Medicine

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>