Nikolaos Pissimissis

The kisspeptin (KiSS-1)/GPR54 system in cancer biology

Kisspeptin (KiSS-1) gene, initially described as a melanoma metastasis suppressor gene, encodes a number of peptides (kp-54, kp-14, kp-13, kp-10), which are endogenous ligands to a G protein-coupled receptor, referred as hOT7T175 or AXOR12 or GPR54. So far intensive investigation has provided substantiate evidence supporting the role of KiSS-1/GPR54 system in cancer biology as well as in the regulation of the reproductive function and trophoblast invasion. The precise mechanism by which KiSS-1/GPR54 system is affecting cancer cell growth and metastasis includes complex endocrine, paracrine and autocrine actions. Nevertheless, the detail mechanism of such actions is still under intensive investigation. Herein we review the evidence which support the role of KiSS-1/GPR54 system in cancer biology.

Molecular markers detecting circulating melanoma cells by reverse transcription polymerase chain reaction: methodological pitfalls and clinical relevance

Abstract Herein, we expound the theory of circulating melanoma cells (CMCs) and their detection with reverse transcription polymerase chain reaction as a molecular staging approach. We discuss the molecular markers that have been used for CMC detection focusing on the use of these markers for multiplex detection analysis. Finally, we comment on the contradictory data of CMC detection studies in the literature and we propose possible solutions which may contribute to the clinical significance of CMC detection in patient management. Clin Chem Lab Med 2009;47:1–11.

Detection of the circulating tumor cells in cancer patients

As the presence of tumor cells circulating in the blood is associated with systemic disease and shortened survival, the establishment of a method to detect circulating tumor cells (CTCs) is of critical importance for a more concise staging and follow-up of cancer patients. Recently, the most robust strategies for the determination of CTCs are the PCR-based methods and the CellSearch® system that exploits the immunofluorescent characterization and isolation of cancer cells. Herein, we analyzed the experimental strategies used for determining CTCs with respect to accuracy, sensitivity and reproducibility in cancers of the breast, colon, prostate and melanoma.

Combined androgen blockade therapy can convert RT-PCR detection of prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) transcripts from positive to negative in the peripheral blood of patients with clinically localized prostate cancer and increase biochemical failure-free survival after curative therapy.

BACKGROUND The clinical relevance of positive molecular staging as defined by reverse transcriptase-polymerase chain reaction (RT-PCR) detections of both prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) transcripts in the peripheral blood (PB) of patients with prostate cancer is still debatable. METHODS We analyzed the biochemical failure-free survival (bFFS) of prostate cancer patients with positive molecular staging who underwent immediate curative therapy (Group I, n=39) compared to prostate cancer patients who did convert their positive molecular staging by the administration of combined androgen blockade (CAB) for 12 months prior to curative treatment (Group II, n=15). RESULTS The median bFFS for Group I was 9 months (95% CI 5-13 months) and was significantly lower compared to Group II (>36 months, p<0.001). In Group I, the median time for PSA values of >2.0 ng/mL was 18 months (95% CI 12-21 months, range 12-36 months). Notably, only one patient from Group II reached PSA values>2.0 ng/mL at 36 months post-curative treatment. CONCLUSIONS In patients with clinically localized prostate cancer and positive RT-PCR detection of PSA and PSMA transcripts in PB, CAB can convert positive molecular staging status to negative and by doing so it modifies the post-curative therapy bFFS of patients with clinically localized prostate cancer.

Methods of detection of circulating melanoma cells: A comparative overview

Disease dissemination is the major cause of melanoma-related death. A crucial step in the metastatic process is the intravascular invasion and circulation of melanoma cells in the bloodstream with subsequent development of distant micrometastases that is initially clinically undetectable and will eventually progress into clinically apparent metastasis. Therefore, the use of molecular methods to detect circulating melanoma cells may be of value in risk stratification and clinical management of such patients. Herein, we review the currently applied techniques for the detection, isolation, enrichment and further characterization of circulating melanoma cells from peripheral blood samples in melanoma patients. Furthermore, we provide a brief overview of the various molecular markers currently being evaluated as prognostic indicators of melanoma progression.

Molecular detection of tyrosinase transcripts in peripheral blood from patients with malignant melanoma: correlation of PCR sensitivity threshold with clinical and pathologic disease characteristics.

Abstract Background: Positive molecular detection of tyrosinase transcripts (TYR mRNA) in RNA extracts of peripheral blood (PB) samples from patients with malignant melanoma provides evidence of disease dissemination. Methods: Total RNA extracted from PB was quantified and subjected to RT-PCR under ultra-sensitive and reduced-sensitivity PCR conditions using SSRT-II. Positive TYR mRNA detection in 78 melanoma patients and 40 healthy volunteers was correlated with clinical stage, Breslows evaluation of tumor thickness, Clarks assessment of tumor invasion, the location of the primary tumor site, and tumor histology. The assay sensitivity was evaluated by spiking PB with the melanoma cell line SK-MEL-28. Results: Using ultra-sensitive PCR conditions, eight out of 40 RNA (20%) samples from healthy volunteers and 50 out of 78 RNA (64.1%) samples from melanoma patients tested positive. Using reduced-sensitivity PCR conditions, we found only two positives in 40 RNA samples from healthy subjects and 20 positives in 78 RNA samples (25.6%) from melanoma patients. Only positive PCR samples for the reduced-sensitivity PCR assay correlated significantly with stage IV (metastatic) disease (p=0.0395). There was no significant correlation between positive TYR mRNA samples for either PCR condition (ultra-sensitive and reduced-sensitivity) with Breslows classification of tumor thickness, Clarks assessment of tumor invasion, location of the primary tumor site, and type of tumor histology. Conclusions: We conclude that reduced-sensitivity rather than ultra-sensitive PCR conditions correlate with clinical stage in melanoma patients. Clin Chem Lab Med 2006;44:1403–9.