Abstract
Castration resistant prostate cancer (CRPC) is an advanced stage of the prostate cancer. Patients suffering from the CRPC exhibit castration levels of testosterone, increasing levels of prostate specific antigen (PSA) and presence of metastases.
Circulating tumor cells (CTCs) are rare cells detached from the primary tumor into the blood stream. They are an important part of the metastatic process.
The presence of CTCs is thus highly probable in the blood of the patients with CRPC and it may allow us to study the role of CTCs in the metastatic process. Our aim is to monitor the presence of CTCs in the blood of the patients with CRPC in the different stages of the treatment.
Ultimately, by comparing our data with the clinical information we shall evaluate the potential of CTCs as a prognostic marker for CRPC. We enriched the fraction of CTCs from the peripheral blood of the patients by the immunomagnetic beads coated with antibodies against EpCAM and HER-2 (AdnaGen, Germany).
We isolated mRNA from this fraction (AdnaGen, Germany). Using the PCR methods we determined the expression of tumor-associated genes: PSMA, PSA and EGFR.
Blood samples were drawn at the time of CRPC diagnosis, after the 4th cycle of systemic therapy and after the complete treatment. Ten patients with CRPC have been tested for the presence of CTCs.
Initially, all of them were identified as CTCs positive with high levels of expression of PSA. PSMA and EGFR have been expressed in very different levels.
This shows that the CTCs are heterogeneous and could be used as a marker for personalised therapy. After the 4th cycle of systemic therapy, we observed a decrease in the levels of the studied genes.
One patient was even CTC negative. Our first results indicate that the CTCs can possibly serve as a powerful prognostic marker and as a marker for the therapy efficiency for the CRPC patients.
We believe that further results will reveal the possibility of their use in personalised medicine.