Panagiotis J. Vlachostergios

Erratum to: Bortezomib represses HIF-1α protein expression and nuclear accumulation by inhibiting both PI3K/Akt/TOR and MAPK pathways in prostate cancer cells

Bortezomib represents the first proteasome inhibitor (PI) with demonstrated antitumor activity in the clinical setting, particularly for treatment of hematological malignancies. At the preclinical level, its action is shown to be mediated by induction of growth arrest and apoptosis in many tumor types, including androgen-dependent (AD) and androgen-independent (AI) prostate cancer (PCa) cells. Hypoxia-inducible factor-1α (HIF-1α), which is directly involved in tumor growth, is one of the most studied and promising molecular targets for anti-cancer therapy and is often overexpressed in PCa. Bortezomib has been reported to impair tumor growth by also inhibiting HIF-1α. In this study, we investigated the effect of bortezomib on the expression, activity and localization of HIF-1α in LNCaP (AD) and PC3 (AI) PCa cells. First, we show that hypoxic upregulation of HIF-1α protein levels and activity involves both the PI3K/Akt/mTOR and p44/42 MAPK pathways. Second, bortezomib inhibits expression of HIF-1α protein under both normoxic and hypoxic conditions, represses HIF-1 transcriptional activity and attenuates the release of vascular endothelial growth factor. These effects correlate with the ability of bortezomib to cause dephosphorylation of phospho-Akt, phospho-p70S6K, and phospho-S6RP, thus inactivating a pathway known to be required for HIF-1α protein expression at the translational level. Furthermore, bortezomib also abrogates p44/42 MAPK phosphorylation, which results to reduced nuclear translocation of HIF-1α. Taken together, these results suggest that bortezomib inhibits HIF-1α protein synthesis and its nuclear targeting through suppression of PI3K/Akt/mTOR and MAPK pathways, respectively, in both AD and AI PCa cells.

Mini Nutritional Assessment (MNA) and biochemical markers of cachexia in metastatic lung cancer patients: Interrelations and associations with prognosis

PURPOSEnLung cancer patients frequently present with weight loss in the context of the cachexia syndrome. Despite its high clinical significance, definite diagnostic criteria of cachexia are lacking. Nutritional screening questionnaires, like the Mini Nutritional Assessment (MNA), have been proposed for the timely diagnosis of the syndrome. The aim of this study was to evaluate the correlation of MNA with laboratory markers of inflammation/cachexia in patients with metastatic lung cancer. The prognostic value of the measured parameters was also examined.nnnPATIENTS AND METHODSnPatients with metastatic lung cancer referred for systemic therapy were eligible. Baseline clinical characteristics were recorded and nutritional status was assessed using MNA. Blood samples were also collected and the following parameters were measured: hemoglobin (Hb), albumin (Alb), C-reactive protein (CRP), ghrelin, adiponectin, leptin and insulin growth factor I (IGF-I).nnnRESULTSnTotally, 115 patients (101 males) [median age 66 years (range 32-86)] were evaluated. According to MNA score, 27 (23.5%) patients were well nourished, 59 (51.3%) were at nutritional risk and 29 (25.2%) were already malnourished at diagnosis. MNA correlated with the following parameters: Hb (p=0.001), albumin (p<0.001), CRP (p=0.002), adiponectin (p=0.037) and leptin (p=0.008). After a median follow up of 38.2 months, multivariate analysis revealed that age (p=0.008), number of metastatic sites (p<0.001), MNA (p=0.044) and leptin (p=0.004) independently correlated with overall survival.nnnCONCLUSIONSnBased on the MNA, the majority of patients were either malnourished or at nutritional risk. MNA correlated with laboratory parameters related to inflammation/cachexia and was independently associated with survival.

Bortezomib overcomes MGMT-related resistance of glioblastoma cell lines to temozolomide in a schedule-dependent manner

SummaryDevelopment of drug resistance after standard chemotherapy for glioblastoma multiforme (GBM) with temozolomide (TMZ) is associated with poor prognosis of GBM patients and is at least partially mediated by a direct DNA repair pathway involving O6-methylguanine methyltransferase (MGMT). This enzyme is under post-translational control by a multisubunit proteolytic cellular machinery, the 26S proteasome. Inhibition of the proteasome by bortezomib (BZ), a boronic acid dipeptide already in clinical use for the treatment of myeloma, has been demonstrated to induce growth arrest and apoptosis in GBM cells. In this study we investigated the effect of sequential treatment with BZ and TMZ on cell proliferation-viability and apoptosis of the human T98G and U87 GBM cell lines. We also tested for an effect of treatment on MGMT expression and important upstream regulators of the latter, including nuclear factor kappa B (NFκB), p44/42 mitogen-activated protein kinase (MAPK), p53, signal transducer and activator of transcription 3 (STAT3) and hypoxia-inducible factor 1α (HIF-1α). The sequence of drug administration for maximal cytotoxicity favored BZ prior to TMZ in T98G cells while the opposite was the case for U87 cells. Maximal efficacy was associated with downregulation of MGMT, reduced IκBα-mediated proteasome-dependent nuclear accumulation of NFκB, attenuation of p44/42 MAPK, AKT and STAT3 activation, and stabilization of p53 and inactive HIF-1α. Collectively, these results suggest that proteasome inhibition by BZ overcomes MGMT-mediated GBM chemoresistance, with scheduling of administration being critical for obtaining the maximal tumoricidal effect of combination with TMZ.

The Glasgow Prognostic Score (GPS) predicts toxicity and efficacy in platinum-based treated patients with metastatic lung cancer

PURPOSEnLung cancer is the most common cause of cancer death. A cumulative prognostic score based on C-reactive protein and albumin, termed the Glasgow Prognostic Score (GPS), indicates the presence of systemic inflammatory response. GPS has been proposed as a powerful prognostic tool for patients with various types of malignant tumors, including lung cancer. The aim of this study was to assess the predictive value of baseline GPS in terms of toxicity and response in lung cancer patients treated with platinum-based chemotherapy.nnnPATIENTS AND METHODSnPatients referred to our institution for consideration of first-line platinum-based treatment were eligible. Demographics and disease-related characteristics were recorded. Toxicity was graded according to NCI CTCAE version 3.0 throughout first-line therapy. GPS was calculated before the onset of treatment and was related to the development of toxicity. Response to first-line therapy and survival data were also collected.nnnRESULTSnTotally, 96 lung cancer patients were accrued. GPS was associated with increased mucositis p=0.004), neurotoxicity (p=0.038), neutropenia (p=0.02), dose reductions or/ and need for granulocyte colony-stimulating factor (G-CSF) support (p=0.005), toxicity-related termination of treatment (p=0.001) and chemotherapy-related toxic deaths (p=0.013). GPS was associated with overall survival (p=0.016) and progression-free survival (p=0.016) as well as response to treatment (p=0.05).nnnCONCLUSIONSnOur data demonstrate that GPS assessment is predictive of the most important aspects of platinum-related toxicity and this may partly explain its associations with poor clinical outcome in patients with metastatic lung cancer.

Evidence of association between methylenetetrahydrofolate reductase gene and susceptibility to breast cancer: a candidate-gene association study in a South-eastern European population.

The methylenetetrahydrofolate reductase (MTHFR) gene has been proposed as a candidate gene for breast cancer (BC). However, the specific role of MTHFR polymorphisms and haplotypes has not been fully clarified and replicated. We examined the association of two common MTHFR polymorphisms (C677T and A1298C) and their haplotypes in a candidate-gene association study, involving 300 female patients with BC and 283 healthy women. The single locus analysis for the two polymorphisms revealed an association only for the C677T polymorphism [odds ratio (95% confidence interval), OR=2.05 (1.21-3.48)], but adjustment for age diminished this association [OR=1.76 (0.92-3.42)]. The menopausal status showed no significant effect in the association between the MTHFR polymorphisms and BC. The analysis of haplotypes showed an association for the C677-A1298 haplotypes (p=0.04). The available evidence from our study may support a contributory role of MTHFR polymorphisms in BC development. Future larger studies may help in elucidating the genetics of BC further.

Inverse baseline expression pattern of the NEP/neuropeptides and NFκB/proteasome pathways in androgen-dependent and androgen-independent prostate cancer cells

BackgroundCastration-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.MethodsWe 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.ResultsAt 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.ConclusionsOur 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.

The ubiquitin-proteasome system in glioma cell cycle control

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.

The ubiquitin‐proteasome system in cancer, a major player in DNA repair. Part 2: transcriptional regulation

•u2002 Introduction •u2002 Transcriptional modifications of DNA repair by UPS ‐u2002 TCR pathway (NER) ‐u2002 Protein‐DNA adducts repair ‐u2002 BER, NER pathways ‐u2002 MMR pathway ‐u2002 MGMT repair pathway ‐u2002 DSBR pathway ‐u2002 FA pathway •u2002 DNA repair as part of UPS‐related stress response •u2002 Conclusions and future perspectives

Baseline Plasma Levels of Interleukin-8 in Stage IV Non-Small-Cell Lung Cancer Patients: Relationship With Nutritional Status and Prognosis

Interleukin (IL)-8 promotes cellular proliferation and angiogenesis in patients with non-small-cell lung cancer (NSCLC) and may be related to cachexia. Our aim was to investigate the relationship of IL-8 levels with nutritional status, and clinical outcome of patients with NSCLC. Patients with metastatic NSCLC referred for first-line therapy were eligible. Baseline IL-8 levels were measured in plasma. The Mini Nutritional Assessment (MNA) was used for the evaluation of the nutritional status, and patients were classified into 3 groups: A (score 24–30) “well nourished,” B (score 17–23.5) “risk of malnutrition,” and C (0–16.5) “malnourishment.” Response to first-line chemotherapy, time-to-tumor progression (TTP), and overall survival (OS) were also recorded. In total, 114 patients (101 males, 88.5%; mean age = 67.5 yr) were evaluated. Performance status was 0–1 in 62% of the patients. According to the MNA, the majority of patients (71%) was either at nutritional risk or malnourished. IL-8 levels were significantly different between MNA groups (P = 0.023) and correlated with TTP (P = 0.013) and OS (P = 0.001) in univariate analysis. Baseline IL-8 levels correlate with the nutritional status of patients with metastatic NSCLC, suggesting that this cytokine may be related with cachexia.

Bortezomib downregulates MGMT expression in T98G glioblastoma cells.

The efficacy of treatment for glioblastoma multiforme is currently limited by the development of resistance, particularly, but not exclusively, due to the expression of the DNA repair enzyme O6-methylguanine methyltransferase (MGMT) in a significant proportion of astrocytic tumors. MGMT is post-translationally regulated by the 26S proteasome, a multi-subunit organelle responsible for degradation of misfolded cellular proteins. The boronic acid dipeptide bortezomib is the first and only proteasome inhibitor in clinical use so far, and has been reported as a strategy to restrict growth and promote apoptosis of glioblastoma cells. In this study we investigated the effect of bortezomib on MGMT expression in T98G cells, looking for an effect on the nuclear factor kappa B (NFκB) pathway, which is a major player in MGMT regulation and is also under tight control by the ubiquitin–proteasome system. Administration of bortezomib led to a significant reduction of T98G cell viability and induction of DNA fragmentation. These effects coincided with reduced expression of MGMT transcript levels, and a decrease in cellular amount and IκBα-mediated, proteasomal activity-dependent nuclear translocation of NFκB. In addition, bortezomib-induced phosphorylation of the translation initiation factor 2alpha (eIF2α) was in parallel with translational repression of MGMT. Taken together, these results suggest a novel role for bortezomib as a potent MGMT inhibitor and support its ongoing testing as a chemosensitizer in glioblastoma.