lhrh--his(5)-trp(7)-tyr(8)- and Prostatic-Neoplasms

Serum testosterone suppression during androgen deprivation therapy has been reported to affect the efficacy of androgen deprivation therapy. However, the factors impacting hormonal variations during androgen deprivation therapy remain unclear. Therefore, in this study we investigated the significance of missense polymorphisms in the gene encoding GNRH in men treated with primary androgen deprivation therapy for metastatic prostate cancer.. This study included 80 Japanese patients with metastatic prostate cancer with available serum testosterone levels during androgen deprivation therapy. We examined the association of GNRH1 (rs6185, S20W) and GNRH2 (rs6051545, A16V) gene polymorphisms with clinicopathological parameters, including serum testosterone levels during androgen deprivation therapy, as well as prognosis, including progression-free and overall survival.. The CT and CT/TT alleles in the GNRH2 gene (rs6051545) were associated with higher serum testosterone during androgen deprivation therapy compared with those of the CC allele. Consequently the CT alleles were associated with a higher risk of progression after adjustment for age and serum testosterone during androgen deprivation therapy (HR 1.73, 95% CI 1.00-3.00, p = 0.049).. Taken together these findings suggest that rs6051545 (GNRH2) genetic variation may result in inadequate suppression of serum testosterone during androgen deprivation therapy. This may lead to detrimental effects of androgen deprivation therapy on prognosis in men with metastatic prostate cancer.

Topics: Aged; Alleles; Androgen Antagonists; Disease Progression; DNA, Neoplasm; Follow-Up Studies; Gonadotropin-Releasing Hormone; Humans; Male; Neoplasm Metastasis; Polymorphism, Genetic; Prognosis; Prostatic Neoplasms; Retrospective Studies; Testosterone; Treatment Outcome

Gonadotropin-releasing hormone-I (GnRH-I) has attracted strong attention as a hormonal therapeutic tool, particularly for androgen-dependent prostate cancer patients. However, the androgen-independency of the cancer in advanced stages has spurred researchers to look for new medical treatments. In previous reports, we developed the GnRH-II antagonist Trp-1 to inhibit proliferation and stimulate the autophagic death of various prostate cancer cells, including androgen-independent cells. We further screened many GnRH-II antagonists to identify molecules with higher efficiency. Here, we investigated the effect of SN09-2 on the growth of PC3 prostate cancer cells. SN09-2 reduced the growth of prostate cancer cells but had no effect on cells derived from other tissues. Compared with Trp-1, SN09-2 conspicuously inhibited prostate cancer cell growth, even at low concentrations. SN09-2-induced PC3 cell growth inhibition was associated with decreased membrane potential in mitochondria where the antagonist was accumulated, and increased mitochondrial and cytosolic reactive oxygen species. SN09-2 induced lactate dehydrogenase release into the media and annexin V-staining on the PC3 cell surface, suggesting that the antagonist stimulated prostate cancer cell death by activating apoptotic signaling pathways. Furthermore, cytochrome c release from mitochondria to the cytosol and caspase-3 activation occurred in a concentration- and time-dependent manner. SN09-2 also inhibited the growth of PC3 cells xenotransplanted into nude mice. These results demonstrate that SN09-2 directly induces mitochondrial dysfunction and the consequent ROS generation, leading to not only growth inhibition but also apoptosis of prostate cancer cells.

Topics: Animals; Antinematodal Agents; Apoptosis; Cell Line, Tumor; Cytochromes c; Gonadotropin-Releasing Hormone; Humans; Lactate Dehydrogenases; Male; Mice; Mice, Nude; Oligopeptides; Prostatic Neoplasms; Signal Transduction

Gonadotropin-releasing hormone-I (GnRH-I) is known to directly regulate prostate cancer cell proliferation. However, the role of GnRH-II in prostate cancer is unclear. Here, we investigated the effect of the GnRH-II antagonist trptorelix-1 (Trp-1) on growth of PC3 prostate cancer cells. Trp-1 induced growth inhibition of PC3 cells in vitro and inhibited growth of PC3 cells xenografted into nude mice. FITC-N3, an FITC-conjugated Trp-1 analogue, was largely present in the mitochondria of prostate cancer cells, but not in other cells that are not derived from the prostate. Trp-1-induced PC3 growth inhibition was associated with decreased mitochondrial membrane potential and increased levels of mitochondrial and cytosolic reactive oxygen species (ROS). Growth inhibition was partially prevented by cotreating cells with N-acetyl cysteine, an antioxidant. Cytochrome c release and caspase-3 activation were not detected in Trp-1-treated cells. However, Trp-1 induced autophagosome formation, as seen by increased LysoTracker staining and recruitment of microtubule-associated protein 1 light chain 3 to these new lysosomal compartments. Trp-1-induced autophagy was accompanied by decreased AKT phosphorylation and increased c-Jun NH(2) terminal kinase phosphorylation, two events known to be linked to autophagy. Taken together, these data suggest that Trp-1 directly induces mitochondrial dysfunction and ROS increase, leading to autophagy of prostate cancer cells. GnRH-II antagonists may hold promise in the treatment of prostate cancer.

Topics: Animals; Autophagy; Caspase 3; Cell Growth Processes; Cell Line, Tumor; Cytochromes c; Female; Gonadotropin-Releasing Hormone; HeLa Cells; Humans; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Mitochondria; Oligopeptides; Prostatic Neoplasms; Reactive Oxygen Species

GnRH II has important functional effects in steroid hormone-dependent tumours. Here we investigated the expression and regulation of GnRH II in prostate cancer. GnRH II protein was equally expressed in benign (73%) and malignant (78%) biopsies studied in a prostate tissue microarray (P = 0.779). There was no relationship between expression and clinical parameters in the cancer cohort. GnRH II was, however, significantly reduced in tumour biopsies following hormone ablation. This was further investigated in a prostate xenograft model where androgens increased GnRH II levels, while their withdrawal reduced it. In cell lines, we confirmed high levels of GnRH II in androgen receptor (AR)-positive LNCaP cells but low levels in AR-negative PC3 cells. In LNCaP cells, GnRH II induction by androgens was blocked by the AR inhibitor casodex, but not by cycloheximide treatment. Sequence analysis subsequently revealed a putative androgen response element in the upstream region of the GnRH II gene and direct interaction with the AR was confirmed in chromatin immunoprecipitation experiments. Finally, to test whether the effects of GnRH II were dependent on AR expression, LNCaP and PC3 cells were exposed to exogenous peptide. In both cell lines, GnRH II inhibited cell proliferation and migration, suggesting that its function is independent of AR status. These results provide evidence that GnRH II is widely expressed in prostate cancer and is an AR-regulated gene. Further studies are warranted to characterise the effects of GnRH II on prostate cancer cells and investigate its potential value as a novel therapy.

Topics: Androgens; Animals; Base Sequence; Binding Sites; Cell Proliferation; Gene Expression Regulation, Neoplastic; Gonadotropin-Releasing Hormone; Humans; Male; Mice; Mice, Nude; Molecular Sequence Data; Neoplasm Invasiveness; Neoplasms, Hormone-Dependent; Prostatic Neoplasms; Receptors, Androgen; Response Elements; Transplantation, Heterologous; Tumor Cells, Cultured

GnRH is known to directly regulate prostate cancer cell proliferation, but the precise mechanism of action of the peptide is still under investigation.. This study demonstrates differential effects of GnRH-I and GnRH-II on androgen-independent human prostate cancer cells.. Both GnRH-I and GnRH-II increased the intracellular Ca(2+) concentration ([Ca(2+)](i)) either through Ca(2+) influx from external Ca(2+) source or via mobilization of Ca(2+) from internal Ca(2+) stores. Interestingly, the [Ca(2+)](i) increase was mediated by activation of the ryanodine receptor but not the inositol trisphosphate receptor. Trptorelix-1, a novel GnRH-II antagonist but not cetrorelix, a classical GnRH-I antagonist, completely inhibited the GnRH-II-induced [Ca(2+)](i) increase. Concurrently at high concentrations, trptorelix-1 and cetrorelix inhibited GnRH-I-induced [Ca(2+)](i) increase, whereas at low concentrations they exerted an agonistic action, inducing Ca(2+) influx. High concentrations of trptorelix-1 but not cetrorelix-induced prostate cancer cell death, probably through an apoptotic process. Using photoaffinity labeling with (125)I-[azidobenzoyl-D-Lys(6)]GnRH-II, we observed that an 80-kDa protein specifically bound to GnRH-II.. This study suggests the existence of a novel GnRH-II binding protein, in addition to a conventional GnRH-I receptor, in prostate cancer cells. These data may facilitate the development of innovatory therapeutic drugs for the treatment of prostate cancer.

Topics: Apoptosis; Calcium; Gonadotropin-Releasing Hormone; Humans; Inositol Phosphates; Male; Photoaffinity Labels; Prostatic Neoplasms; Receptors, LHRH; Reverse Transcriptase Polymerase Chain Reaction; Ryanodine Receptor Calcium Release Channel; Signal Transduction