Search

Abstract A major determinant of cell fate is regulation of cell cycle. Tight regulation of this process is lost during the course of development and progression of various tumors. The ubiquitin-proteasome system (UPS) constitutes a universal protein degradation pathway, essential for the consistent recycling of a plethora of proteins with distinct structural and functional roles within the cell, including cell cycle regulation. High grade tumors, such as glioblastomas have an inherent potential of escaping cell cycle control mechanisms and are often refractory to conventional treatment. Here, we review the association of UPS with several UPS-targeted proteins and pathways involved in regulation of the cell cycle in malignant gliomas, and discuss the potential role of UPS inhibitors in reinstitution of cell cycle control.

Abstract Background The aim was to compare two standard chemotherapy regimens combined with bevacizumab as first-line treatment in patients with metastatic colorectal cancer. Methods Patients previously untreated for metastatic disease were randomized in: group A (irinotecan, capecitabine, bevacizumab, every 3 weeks; XELIRI-bevacizumab) and group B (irinotecan, leucovorin, fluorouracil, bevacizumab, every 2 weeks; FOLFIRI-bevacizumab). Primary endpoint was progression-free survival (PFS). Plasma concentrations of nitric oxide, osteopontin, TGF-β1 and VEGF-A were measured at baseline and during treatment. Results Among 285 eligible patients, 143 were randomized to group A and 142 to group B. Fifty-five patients (38.5%) in group A and 57 (40.1%) in group B responded (p = 0.81). After a median follow-up of 42 months, median PFS was 10.2 and 10.8 months (p = 0.74), while median OS was 20.0 and 25.3 months (p = 0.099), for groups A and B, respectively. Most frequent grade 3–4 toxicities (group A vs group B) were neutropenia (13% vs 22%, p = 0.053) and diarrhea (19% vs 11%, p = 0.082). Baseline plasma osteopontin concentrations demonstrated prognostic significance for both PFS and OS. Conclusions This trial did not show significant differences in efficacy between the groups. However, the toxicity profile was different. Baseline plasma osteopontin concentrations demonstrated independent prognostic significance. (Registration number: ACTRN12610000270011)

Abstract Background Upregulation of nuclear factor kappa B (NFκB) activity and neuroendocrine differentiation are two mechanisms known to be involved in prostate cancer (PC) progression to castration resistance. We have observed that major components of these pathways, including NFκB, proteasome, neutral endopeptidase (NEP) and endothelin 1 (ET-1), exhibit an inverse and mirror image pattern in androgen-dependent (AD) and -independent (AI) states in vitro. Methods We have now investigated for evidence of a direct mechanistic connection between these pathways with the use of immunocytochemistry (ICC), western blot analysis, electrophoretic mobility shift assay (EMSA) and proteasome activity assessment. Results Neuropeptide (NP) stimulation induced nuclear translocation of NFκB in a dose-dependent manner in AI cells, also evident as reduced total inhibitor κB (IκB) levels and increased DNA binding in EMSA. These effects were preceded by increased 20 S proteasome activity at lower doses and at earlier times and were at least partially reversed under conditions of NP deprivation induced by specific NP receptor inhibitors, as well as NFκB, IκB kinase (IKK) and proteasome inhibitors. AD cells showed no appreciable nuclear translocation upon NP stimulation, with less intense DNA binding signal on EMSA. Conclusions Our results support evidence for a direct mechanistic connection between the NPs and NFκB/proteasome signaling pathways, with a distinct NP-induced profile in the more aggressive AI cancer state.

Abstract Background Castration-resistance in prostate cancer (PC) is a critical event hallmarking a switch to a more aggressive phenotype. Neuroendocrine differentiation and upregulation of NFκB transcriptional activity are two mechanisms that have been independently linked to this process. Methods We investigated these two pathways together using in vitro models of androgen-dependent (AD) and androgen-independent (AI) PC. We measured cellular levels, activity and surface expression of Neutral Endopeptidase (NEP), levels of secreted Endothelin-1 (ET-1), levels, sub-cellular localisation and DNA binding ability of NFκB, and proteasomal activity in human native PC cell lines (LnCaP and PC-3) modelling AD and AI states. Results At baseline, AD cells were found to have high NEP expression and activity and low secreted ET-1. In contrast, they exhibited a low-level activation of the NFκB pathway associated with comparatively low 20S proteasome activity. The AI cells showed the exact mirror image, namely increased proteasomal activity resulting in a canonical pathway-mediated NFκB activation, and minimal NEP activity with increased levels of secreted ET-1. Conclusions Our results seem to support evidence for divergent patterns of expression of the NFκB/proteasome pathway with relation to components of the NEP/neuropeptide axis in PC cells of different level of androgen dependence. NEP and ET-1 are inversely and directly related to an activated state of the NFκB/proteasome pathway, respectively. A combination therapy targeting both pathways may ultimately prove to be of benefit in clinical practice.

Abstract Background Sunitinib is an oral, multitargeted tyrosine kinase inhibitor that has been approved for the treatment of metastatic renal cell carcinoma. Although the majority of sunitinib-treated patients receive a clinical benefit, almost a third of the patients will not respond. Currently there is no available marker that can predict for response in these patients. Methods We estimated the plasma levels of NT-pro-BNP (the N-terminal precursor of brain natriuretic peptide) in 36 patients that were treated with sunitinib for metastatic clear-cell renal carcinoma. Results From the 36 patients, 9 had progressive disease and 27 obtained a clinical benefit (objective response or disease stabilization). Increases in plasma NT-pro-BNP were strongly correlated to clinical outcome. Patients with disease progression increased plasma BNP at statistically significant higher levels than patients that obtained a clinical benefit, and this was evident from the first 15 days of treatment (a three-fold increase in patients with progressive disease compared to stable NT-pro-BNP levels in patients with clinical benefit, p < 0.0001). Median progression-free survival was 12.0 months in patients with less than 1.5 fold increases (n = 22) and 3.9 months in patients with more than 1.5 fold increases in plasma NT-pro-BNP (n = 13) (log-rank test, p = 0.001). Conclusions This is the first time that a potential "surrogate marker" has been reported with such a clear correlation to clinical benefit at an early time of treatment. Due to the relative small number of accessed patients, this observation needs to be further addressed on larger cohorts. More analyses, including multivariate analyses are needed before such an observation can be used in clinical practice.

Abstract Introduction Primary osteosarcoma is one of the rare tumors affecting the urinary bladder. The occurrence of osteosarcoma in a patient with a long history of transitional cell carcinoma of the bladder is even more uncommon. Case presentation We present the case of a 74-year-old Greek man who was diagnosed with osteosarcoma 10 years after he had been diagnosed with transitional cell carcinoma of the bladder from which he had been free from recurrences for the past three years. Our patient was treated for the osteosarcoma with transurethral resection of bladder tumor and external beam radiation therapy. He died eight months after the diagnosis, suffering poor quality of life in the last months. Conclusion Osteosarcoma of the bladder has a dismal prognosis. External beam radiation therapy as an adjunct to transurethral resection of bladder tumor not only provides no benefit to patients with primary osteosarcoma of urinary bladder, but also may be associated with poor quality of life.

Abstract Background The treatment paradigm in advanced renal cell carcinoma (RCC) has changed in the recent years. Sunitinib has been established as a new standard for first-line therapy. We studied the prognostic significance of baseline characteristics and we compared the risk stratification with the established Memorial Sloan Kettering Cancer Center (MSKCC) model. Methods This is a retrospective analysis of patients treated in six Greek Oncology Units of HECOG. Inclusion criteria were: advanced renal cell carcinoma not amenable to surgery and treatment with Sunitinib. Previous cytokine therapy but no targeted agents were allowed. Overall survival (OS) was the major end point. Significance of prognostic factors was evaluated with multivariate cox regression analysis. A model was developed to stratify patients according to risk. Results One hundred and nine patients were included. Median follow up has been 15.8 months and median OS 17.1 months (95% CI: 13.7-20.6). Time from diagnosis to the start of Sunitinib (12 months, p = 0.001), number of metastatic sites (1 vs. >1, p = 0.003) and performance status (PS) (1, p = 0.001) were independently associated with OS. Stratification in two risk groups ("low" risk: 0 or 1 risk factors; "high" risk: 2 or 3 risk factors) resulted in distinctly different OS (median not reached [NR] vs. 10.8 [95% confidence interval (CI): 8.3-13.3], p < 0.001). The application of the MSKCC risk criteria resulted in stratification into 3 groups (low and intermediate and poor risk) with distinctly different prognosis underlying its validity. Nevertheless, MSKCC model did not show an improved prognostic performance over the model developed by this analysis. Conclusions Studies on risk stratification of patients with advanced RCC treated with targeted therapies are warranted. Our results suggest that a simpler than the MSKCC model can be developed. Such models should be further validated.