Inhibition of the angiotensin II type 2 receptor AT2R is a novel therapeutic strategy for glioblastoma.

Glioblastoma (GBM) is an aggressive malignant primary brain tumor with limited therapeutic options. We show that the angiotensin II (AngII) type 2 receptor (AT2R) is a therapeutic target for GBM and that AngII, endogenously produced in GBM cells, promotes proliferation through AT2R. We repurposed EMA401, an AT2R antagonist originally developed as a peripherally restricted analgesic, for GBM and showed that it inhibits the proliferation of AT2R-expressing GBM spheroids and blocks their invasiveness and angiogenic capacity. The crystal structure of AT2R bound to EMA401 was determined and revealed the receptor to be in an active-like conformation with helix-VIII blocking G-protein or ß-arrestin recruitment. The architecture and interactions of EMA401 in AT2R differ drastically from complexes of AT2R with other relevant compounds. To enhance central nervous system (CNS) penetration of EMA401, we exploited the crystal structure to design an angiopep-2-tethered EMA401 derivative, A3E. A3E exhibited enhanced CNS penetration, leading to reduced tumor volume, inhibition of proliferation, and increased levels of apoptosis in an orthotopic xenograft model of GBM.

Elevated basal antibody-dependent cell-mediated cytotoxicity (ADCC) and high epidermal growth factor receptor (EGFR) expression predict favourable outcome in patients with locally advanced head and neck cancer treated with cetuximab and radiotherapy.

BACKGROUND: Antibody-dependent cell-mediated cytotoxicity (ADCC) may contribute to the antitumor activity of cetuximab. However, the extent of this contribution is unclear. In this study, we investigated the impact of baseline ADCC on the outcome of patients with locally advanced squamous cell carcinoma treated with cetuximab and radiotherapy. METHODS: We determined baseline ADCC in 28 patients treated with cetuximab and radiotherapy and in 15 patients treated with chemoradiation. We linked the values observed with complete response and with overall survival. We also considered the role of epidermal growth factor receptor (EGFR) expression and studied the combined effect of EGFR and ADCC. RESULTS: We observed a wide range of baseline values of ADCC. Complete response did not correlate with either ADCC or EGFR expression. However, when ADCC and EGFR were considered together using a mixed score, they significantly correlated with achieving a complete response (p = 0.04). High baseline ADCC significantly correlated with outcome compared to low (p = 0.03), but not in patients treated without cetuximab. Patients showing high baseline levels of both ADCC and EGFR3+ achieved the best outcome compared to the others (p = 0.02). CONCLUSIONS: In this study, patients treated with cetuximab and radiotherapy, showing high baseline of both ADCC and EGFR3+, have significant higher probability of achieving a complete response and a long overall survival compared to the others.

Schedule-dependent interaction between temsirolimus and cetuximab in head and neck cancer: a preclinical study.

Aberrant epidermal growth factor receptor (EGFR) signaling is associated with tumor growth in head and neck squamous cell carcinoma (HNSCC) and is a major focus of targeted therapy. The phosphatidylinositol-3-kinase/AKT/mammalian target of the rapamycin (PI3K/AKT/mTOR) signaling pathway is frequently mutated in HNSCC and is involved in disease progression and resistance to EGFR inhibitors. The aim of this study was to assess the antiproliferative effects of mTOR inhibition (temsirolimus) combined with the anti-EGFR monoclonal antibody cetuximab, administered according to different combination schedules. Antiproliferative effects of the combination of temsirolimus and cetuximab were determined on the representative HNSCC CAL33 cell line (PI3KCA H1047R mutated and K-RAS wild-type). In addition, key proteins related to the EGFR pathway (pEGFR/EGFR, pAKT/AKT) and the mTOR pathway (p-p70S6K1, p4E-BP1) were determined to explain the cytotoxic effects. Temsirolimus and cetuximab showed a synergistic effect when administered in combination. Supra-additive effect was lost when the two drugs were administered sequentially, irrespective of which drug was administered first. Synergistic effect of the combination was corroborated by a marked downregulation of pEGFR, significant downregulation of pAKT expression, and a marked diminution of p70S6K1 and p4E-BP1 expression. Our study demonstrated a synergistic effect of temsirolimus and cetuximab administered in combination, well illustrated by a simultaneous blockade of intracellular signaling pathways regulating cell proliferation and survival. These results establish the notion of a schedule dependency for the combined treatment, which can be of importance at the clinical level.

The effect of paclitaxel and nab-paclitaxel in combination with anti-angiogenic therapy in breast cancer cell lines.

Taxanes represent a treatment of choice for metastatic breast cancer. Their combination with bevacizumab improved response rate and progression-free survival. We studied in vitro the effect on cell survival of the combination of either paclitaxel or nab-paclitaxel with bevacizumab and we investigated the biological factors involved in the response to treatments. We used two breast cancer cell lines, MCF7 (ER+/HER2-) and MDA-MB-231 (ER-/HER2-), co-cultured with or without HUVEC cells. We analysed cell survival by MTT test, VEGF secretion by ELISA and VEGFR, SPARC, MDR1 expression by western blot. Doses of both taxanes causing a 50 % growth inhibition were higher in MCF7 than MDA-MB-231, suggesting that taxanes are more effective in ER- cell lines. When both cell lines were grown as single culture, the combination bevacizumab+paclitaxel showed a similar anti-proliferative effect compared to paclitaxel alone. The association bevacizumab+nab-paclitaxel was more effective than nab-paclitaxel alone. An increased anti-proliferative effect of bevacizumab+paclitaxel was observed when MDA-MB-231 cells were cultured with HUVEC. We detected an induction of VEGF secretion when MDA-MB-231 cells were treated with either taxanes. Paclitaxel caused a reduction of VEGF in MCF7. SPARC resulted up-regulated in both cell lines treated with bevacizumab+nab-paclitaxel. Nab-paclitaxel seems to play an important role in inhibiting tumor proliferation through albumin-SPARC bound in association with bevacizumab compared to taxanes alone in both breast cancer cells. The addition of bevacizumab to paclitaxel increased its activity only in ER- cells. This difference might be due to their ER status.

Treatment effect of buparlisib, cetuximab and irradiation in wild-type or PI3KCA-mutated head and neck cancer cell lines.

Introduction In complement to anti-EGFR therapy, the targeting of PI3K/AKT/mTOR signaling pathway is of particular interest in the management of Head and Neck Squamous Cell Carcinoma (HNSCC). Here, we assess the effects of PI3K inhibition combined with anti-EGFR monoclonal antibody cetuximab and/or irradiation (RT). Material and methods Anti-proliferative effects of the combination of buparlisib (a specific PI3K inhibitor), cetuximab and RT was determined in two HNSCC cell lines (CAL33, PI3KCA H1047R-mutated and CAL27, PI3KCA wild-type). We examined biochemical factors related to proliferation, apoptosis (caspases), DNA repair (ERCC1, XRCC1) and the PI3K pathway (pEGFR/EGFR, pAKT/AKT, p-p70, p4EBP1). Results The best synergistic combined treatment in inhibiting cell proliferation was sequence 2 (cetuximab followed by buparlisib) in both cell lines. Addition of RT increased sequence 2 anti-proliferative effect only in CAL27. Data on protein expression indicated a possible activation of mTORC2 complex and caspases proteins in CAL27 not seen in CAL33. In CAL33, the synergistic anti-proliferative effect of the two drugs may derive from the higher sensitivity of mutated cells to PI3K targeting. Conclusions Our study demonstrates a synergistic effect of cetuximab followed by buparlisib in both PI3KCA wild-type and mutated cells, even with different intracellular signaling cross-talk depending on mutational status.

Role of IL-8 induced angiogenesis in uveal melanoma.

Introduction Uveal melanoma (UM) is a highly vascularised tumour generally treated with radiotherapy (RT). A recent preclinical study from our group [1] demonstrated that RT-associated anti-angiogenic therapy has more than additive effects on cell growth, by modulating vascular endothelial growth factor (VEGF) levels. The pro-angiogenic interleukin-8 (IL-8) is highly expressed in both tumour and endothelial cells and is associated with resistance to VEGF-targeted therapies in various tumour types. The aim of this study is to investigate IL-8 release in response to the anti-angiogenic drug bevacizumab (AV) and RT given alone and in combination. Material and methods The human ocular melanoma cells (OCM-1) and human umbilical vein endothelial cells (HUVEC) were grown in transwell plates. AV was administered at a 2,500 µg/ml dose and cells were irradiated with a 6 Gy dose. IL-8 concentrations were determined by ELISA assay. Protein expression was detected by western blot. Results AV alone or in combination with RT reduces VEGF levels in both cell lines when co-cultured; unexpectedly, RT alone did not increase VEGF levels. In transwell plate AV alone lowered IL-8 secretion in both cell lines. This inhibitory effect was reduced when co-cultured cells are treated with AV + RT, suggesting that RT-induced VEGF may reactivate IL-8 secretion, enhancing an alternative pathway to sustain tumour angiogenesis. Conclusions These data indicate that the UM microenvironment, beside VEGF, can activate IL-8 signalling as an alternative pro-angiogenic pathway.

Combination of bevacizumab and irradiation on uveal melanoma: an in vitro and in vivo preclinical study.

BACKGROUND: Radiotherapy (RT) is the standard treatment for uveal melanoma. However it can cause damage to the retina and optic nerve. This study examined the in vitro and in vivo effects of the anti-VEGF monoclonal antibody bevacizumab associated with radiotherapy (RT) on tumor growth and tumor proliferation and vasculature on OCM-1 human uveal melanoma cell line. METHODS: The anti-proliferative effects of bevacizumab, RT and their combination were tested both in vitro (OCM-1 cells co-cultured with HUVEC cells in Transwell plates) and in vivo (OCM-1 tumor xenografts in nude mice). In addition, treatment effects in vitro on VEGF secretion, as well as treatment effects in vivo on tumor proliferation (Ki67 labelling), tumor vasculature (VEGFR2 labelling) and VEGF tumoral concentration were analyzed. RESULTS: Bevacizumab given alone had a significant impact on tumor growth in vivo (and moderate effects in vitro). The bevacizumab-RT combination had additive effects in vitro (tumor cell proliferation) and in vivo (tumor growth), which translated into a significant decrease in Ki67 expression, VEGFR2 labelling and VEGF tumoral content. CONCLUSIONS: The bevacizumab-RT combination could be a promising clinical option to explore for the management of human uveal melanoma, since it may allow RT dose reduction without loss of antitumor efficacy.

Differential molecular mechanism of docetaxel-octreotide combined treatment according to the docetaxel-resistance status in PC3 prostate cancer cells.

To examine the effect and the molecular mechanisms of the combined treatment of the somatostatin (SST) analogue octreotide with docetaxel: analysis of proliferation, apoptosis and migration in the human prostate cancer cell line PC3, either sensitive (PC3wt) or made resistant to docetaxel (PC3R). We examined the effect of the two drugs individually or in combination on cell proliferation and migration by analysis of apoptosis and cell cycle proteins. The role of octreotide in modulating P-glycoprotein function was examined together with the modulation of SST receptors type 2 and 5 (SSTR2 and SSTR5). We observed an enhanced effect of docetaxel and octreotide given in combination or in sequence compared with either agent alone; this result was particularly evident when docetaxel was given before octreotide in PC3wt and when the two drugs were given together in PC3R cells. In contrast to lanreotide, our data indicate that octreotide does not act as a P-glycoprotein inhibitor in PC3R cells. A role of docetaxel and combined treatment in regulating SSTR2, SSTR5, proliferation and apoptosis gene expression is suggested as the possible mechanism for the enhanced effect observed. In addition, an evaluation of the effect of the combined treatment on cellular migration was examined, showing a moderate loss of invasive properties in PC3R cells. The present results confirm that SST analogues may be combined with docetaxel to increase the antitumour effect in patients with advanced prostate carcinoma.

Loss of reelin expression in breast cancer is epigenetically controlled and associated with poor prognosis.

Reelin is a secreted, signaling protein associated with neuronal cell positioning and migration. Recently, reelin was found to be epigenetically silenced in gastric and pancreatic cancers in which down-regulation was associated with increased migratory ability and reduced survival. Here we analyzed reelin expression by immunohistochemistry in 17 normal breast tissue samples from reduction mammoplasties and in two independent tissue microarrays of 136 and more than 2000 breast cancer biopsy samples, respectively. Results were analyzed with regard to clinical parameters, including BRE (Bloom, Richardson, Elston) grade, nodal status, estrogen receptor and HER2 status, and overall survival. Reelin was expressed in the luminal epithelium and myoepithelium of the normal human breast but not in cancerous breasts. Loss of reelin protein expression correlated significantly with decreased survival (P=0.01) and positive lymph node status (P<0.001). By measuring reelin expression and promoter methylation status in 39 primary breast tumors, as well as in breast cancer-derived cell lines before and after decitabine treatment, we established that reelin expression levels correlated inversely with promoter methylation status, whereas demethylation increased reelin mRNA expression in vitro. Reelin overexpression in MDA-MB231 cells, as well as incubation with recombinant reelin, suppressed cell migration, invadopodia formation, and invasiveness in vitro. We conclude that reelin may play an important role in controlling invasiveness and metastatic potential of breast cancer cells and that its expression is controlled by promoter methylation.

The renin angiotensin system (RAS) mediates bifunctional growth regulation in melanoma and is a novel target for therapeutic intervention.

Despite emergence of new systemic therapies, metastatic melanoma remains a challenging and often fatal form of skin cancer. The renin-angiotensin system (RAS) is a major physiological regulatory pathway controlling salt-water equilibrium, intravascular volume and blood pressure. Biological effects of the RAS are mediated by the vasoactive hormone angiotensin II (AngII) via two receptor subtypes, AT1R (encoded by AGTR1) and AT2R (encoded by AGTR2). We report decreasing expression and increasing CpG island methylation of AGTR1 in metastatic versus primary melanoma and detection in serum of methylated genomic DNA from the AGTR1 CpG island in metastatic melanoma implying that AGTR1 encodes a tumour suppressor function in melanoma. Consistent with this hypothesis, antagonism of AT1R using losartan or shRNA-mediated knockdown in melanoma cell lines expressing AGTR1 resulted in acquisition of the ability to proliferate in serum-free conditions. Conversely, ectopic expression of AGTR1 in cell lines lacking endogenous expression inhibits proliferation irrespective of the presence of AngII implying a ligand-independent suppressor function for AT1R. Treatment of melanoma cell lines expressing endogenous AT2R with either AngII or the AT2R-selective agonist Y6AII induces proliferation in serum-free conditions whereas the AT2R-specific antagonists PD123319 and EMA401 inhibit melanoma growth and angiogenesis and potentiate inhibitors of BRAF and MEK in cells with BRAF V600 mutations. Our results demonstrate that the RAS has both oncogenic and tumour suppressor functions in melanoma. Pharmacological inhibition of AT2R may provide therapeutic opportunities in melanomas expressing this receptor and AGTR1 CpG island methylation in serum may serve as a novel biomarker of metastatic melanoma.

Collagen Prolyl Hydroxylases Are Bifunctional Growth Regulators in Melanoma.

Appropriate post-translational processing of collagen requires prolyl hydroxylation, catalyzed by collagen prolyl 3-hydroxylase and collagen prolyl 4-hydroxylase, and is essential for normal cell function. Here we have investigated the expression, transcriptional regulation, and function of the collagen prolyl 3-hydroxylase and collagen prolyl 4-hydroxylase families in melanoma. We show that the collagen prolyl 3-hydroxylase family exemplified by Leprel1 and Leprel2 is subject to methylation-dependent transcriptional silencing in primary and metastatic melanoma consistent with a tumor suppressor function. In contrast, although there is transcriptional silencing of P4HA3 in a subset of melanomas, the collagen prolyl 4-hydroxylase family members P4HA1, P4HA2, and P4HA3 are often overexpressed in melanoma, expression being prognostic of worse clinical outcomes. Consistent with tumor suppressor function, ectopic expression of Leprel1 and Leprel2 inhibits melanoma proliferation, whereas P4HA2 and P4HA3 increase proliferation, and particularly invasiveness, of melanoma cells. Pharmacological inhibition with multiple selective collagen prolyl 4-hydroxylase inhibitors reduces proliferation and inhibits invasiveness of melanoma cells. Together, our data identify the collagen prolyl 3-hydroxylase and collagen prolyl 4-hydroxylase families as potentially important regulators of melanoma growth and invasiveness and suggest that selective inhibition of collagen prolyl 4-hydroxylase is an attractive strategy to reduce the invasive properties of melanoma cells.

DUSP2 methylation is a candidate biomarker of outcome in head and neck cancer.

BACKGROUND: Biomarkers predictive of response to chemoradiotherapy (CRT) regimens for locally advanced head and neck squamous cell carcinoma (LA-HNSCC) are urgently required to identify patients in whom this approach is likely to be effective. TP53 mutations and epidermal growth factor (EGFR) overexpression are common markers of disease. Dual-specificity-phosphatase-2 (DUSP2) has an essential role in cell proliferation, cancer and immune responses. METHODS: Aberrant DUSP2 methylation was investigated by pyrosequencing in 5 HNSCC cell lines, 112 LA-HNSCC tumours. EGFR was investigated by immunohistochemistry and TP53 was analysed by sequencing. RESULTS: We demonstrate methylation-dependent transcriptional silencing of DUSP2 in HNSCC cell lines. In LA-HNSCC patients, aberrant methylation in the DUSP2 CpG island was present in 51/112 cases (45.5%). LA-HNSCC cases with wild-type TP53, overexpression of EGFR and unmethylated DUSP2 had the worst overall survival (P≤0.001). CONCLUSIONS: DUSP2 methylation, when combined with EGFR and TP53, is a candidate biomarker of clinical outcome in LA-HNSCC treated with CRT.

Inhibition of the Polyamine Synthesis Pathway Is Synthetically Lethal with Loss of Argininosuccinate Synthase 1.

Argininosuccinate synthase 1 (ASS1) is the rate-limiting enzyme for arginine biosynthesis. ASS1 expression is lost in a range of tumor types, including 50% of malignant pleural mesotheliomas. Starving ASS1-deficient cells of arginine with arginine blockers such as ADI-PEG20 can induce selective lethality and has shown great promise in the clinical setting. We have generated a model of ADI-PEG20 resistance in mesothelioma cells. This resistance is mediated through re-expression of ASS1 via demethylation of the ASS1 promoter. Through coordinated transcriptomic and metabolomic profiling, we have shown that ASS1-deficient cells have decreased levels of acetylated polyamine metabolites, together with a compensatory increase in the expression of polyamine biosynthetic enzymes. Upon arginine deprivation, polyamine metabolites are decreased in the ASS1-deficient cells and in plasma isolated from ASS1-deficient mesothelioma patients. We identify a synthetic lethal dependence between ASS1 deficiency and polyamine metabolism, which could potentially be exploited for the treatment of ASS1-negative cancers.

E1 detection as prognosticator in human papillomavirus-positive head and neck cancers.

PURPOSE: HPV-related locally advanced head and neck cancers (LA-HNCs) show a good prognosis. This study aimed to investigate the HPV prevalence in LA-HNCs and compare the prognostic value of E1, E6 and L1 genomic viral fragments and p16, individually and in combination, in order to find the best prognosticator in terms of overall survival (OS) and progression-free survival (PFS). PATIENTS AND METHODS: HPV16 was searched in 255 LA-HNC formalin-fixed paraffin-embedded tumor tissues, 89 oropharyngeal cancers (OPCs), and 166 non-OPCs by DNA-PCR with 3 primer pairs. p16 was analyzed by immunohistochemistry in 235 patients. RESULTS: The prevalence of positive samples decreased constantly from E6 to L1 and E1 in both OPCs and non-OPCs. Each LA-HNC patient highlighted variable positivity for each fragment. OPCs showed a higher prevalence of positive samples compared to non-OPCs.Positive coexistence of all the fragments was more common in OPCs (31.5%) than non-OPCs (4.2%), and E1 detection was always associated with E6 and L1. E1-positive OPCs showed improved OS (p = 0.012) and PFS (p = 0.036), while L1- or E6-positive ones did not. p16-positive patients were more prevalent in the OPC (29.8%) than the non-OPC group (7.3%) (p<0.0001) and its prognostic value was not superior to that of E1. However, the multivariate Cox analysis which included E1, L1, E6 status and p16 expression did not show a significant p value. CONCLUSIONS: Though HPV16 positivity measured by DNA-PCR was higher for L1 and E6, they performed weakly as prognosticators; E1 might become a strong prognostic marker for OS and PFS in OPCs.

Correlation of TP53 and MDM2 genotypes and clinical outcome in platinum-treated head and neck cancer patients with more than 10 years' follow-up.

PURPOSE: Adequate biomarkers are still required to optimize therapy in patients with locally advanced head and neck squamous carcinomas (HNSCC) treated with chemoradiotherapy (CRT). METHODS: We updated the follow-up of 66 HNSCC patients treated with CRT we described more than 10 years ago, focusing on SNP Arg/Pro (R/P) at codon 72 and somatic mutations in TP53 and on SNP309 in the MDM2 gene. RESULTS: In wild-type TP53 cases, overall survival (OS) was longer in 72RR and less favorable in 72PP (p = 0.005); when TP53 was mutated, OS was longest in 72PP and less favorable in 72RR and 72RP (p = 0.058). Median OS was significantly shorter in patients with MDM2 SNP309 GG or GT genotypes compared with the TT genotype (p = 0.002). CONCLUSIONS: TP53 SNP72 may be useful in selecting patients for CRT, but has to be related to somatic TP53 mutations. The MDM2 SNP309, easily determined in peripheral blood, might be more convenient as a predictive biomarker.

Reoxygenation Reverses Hypoxia-related Radioresistance in Head and Neck Cancer Cell Lines.

BACKGROUND/AIM: Head and neck cancer (HNC) is characterized by epidermal growth factor receptor (EGFR) overexpression and radiotherapy (RT) resistance. Cancer cells are able to survive and proliferate in hypoxic conditions. Hypoxia can be transiently interrupted by phases of reoxygenation. This work aimed to analyze the reoxygenation effect on proliferation in response to radiation in HNC cells. MATERIALS AND METHODS: HNC cell lines CAL33 and CAL166 were subjected to an 8-Gy radiation dose in hypoxia and/or after reoxygenation. Cell proliferation and molecular factors involved in response to treatments were studied. RESULTS: Cytotoxicity test confirmed radioresistance in hypoxia and highlighted that reoxygenation before RT restores sensitivity in both cell lines. Our results showed a similar proliferation inhibition effect and EGFR modulation but a different cell death mechanism in the two cell lines after treatment. CONCLUSION: Reoxygenation before RT rescued radiosensitivity in HNC cells.

The relevance of ADCC for EGFR targeting: A review of the literature and a clinically-applicable method of assessment in patients.

BACKGROUND: Advances in the understanding of tumor biology have led to the development of targeted therapies as monoclonal antibodies (MoAbs) in clinical oncology. Among their suggested mechanisms of action monoclonal antibodies (IgG1) selectively directed against tumor membrane receptors mediate of antibody-dependent cellular cytotoxicity (ADCC) by triggering Fc-γRIII on natural killer (NK) cells. METHODS: This study reviews the clinical context of ADCC measurement with a particular focus on EGFR targeting and describes an ex vivo ADCC method applied to MoAbs (cetuximab and panitumumab), against epidermal growth factor receptor (EGFR). The test performance was evaluated on different target cells lines (CAL166, A431, HNO91, CAL27), with different effector cells (peripheral blood mononuclear cells or natural killers -NK-) and in various experimental conditions, in order to establish a truly clinically applicable method. RESULTS: Using the experience available in the published literature, we optimized all variables involved in the experimental design: target cells type, numbers and ratio target cells and NK cells (effector cells) per well, time of exposure and repeatability. CONCLUSION: ADCC measurement may be of clinical relevance in the context of treatment with MoAbs. This study describes a non-radioactive method which has proven satisfactory in terms of sensitivity, reproducibility, feasibility and cost effectiveness for the measurement of ADCC activity mediated by NK with an orientation towards the EGFR target.

MGMT promoter methylation and glioblastoma: a comparison of analytical methods and of tumor specimens.

It is already well known that hypermethylation of the O6-methylguanine DNA methyltransferase (MGMT) gene promoter is a predictive biomarker of response to temozolomide treatment and of favorable outcomes in terms of overall survival (OS) and progression-free survival (PFS) in glioblastoma (GBM) patients. Nevertheless, MGMT methylation status has not currently been introduced into routine clinical practice, as the choice of the ideal technique and tissue sample specimen is still controversial. The aim of this study was to compare 2 analytical methods, methylation-specific polymerase chain reaction (MSP) and pyrosequencing (PSQ), and their use on 2 different tissue type samples, snap-frozen and formalin-fixed paraffin-embedded (FFPE), obtained from a single-center and uniformly treated cohort of 46 GBM patients. We obtained methylation data from all frozen tissues, while no results were obtained for 5 FFPE samples. The highest concordance for methylation was found on frozen tissues (88.5%, 23/26 samples), using PSQ (76.7%, 23/30 samples). Moreover, we confirmed that OS and PFS for patients carrying methylation of the MGMT promoter were longer than for patients with an unmethylated promoter. In conclusion, we considered MSP a limited technique for FFPE tissues due to the high risk of false-positive results; in contrast, our data indicated PSQ as the most powerful method to stratify methylated/unmethylated patients as it allows reaching quantitative results with high sensitivity and specificity. Furthermore, frozen tumor tissues were shown to be the best specimens for MGMT methylation analysis, due to the low DNA degradation and homogeneity in methylation throughout the tumor.

A PNA-mediated clamping PCR for routine detection of KRAS mutations in colorectal carcinoma.

The detection of somatic mutations in a tumor represents a valuable tool for tumor characterization and provides the clinicians with information for setting up the most appropriate therapy. KRAS mutations in codons 12 and 13 are important biomarkers routinely analyzed in the clinic for the management of anti-EGFR treatment in colorectal carcinoma (CRC). Here we report a sensitive and inexpensive assay for KRAS mutations based on a PNA-mediated PCR clamping. The assay displays very high sensitivity (0.7%) and specificity (96.7%) when compared to traditional sequencing (SS) and pyrosequencing (PS), two of the most commonly and routinely used methods employed today by diagnostic laboratories. Furthermore, the PNA assay requires only basic and low-cost laboratory equipment, in contrast with all the most recent PCR-based technologies, which are highly sensitive but also much more expensive. Finally, despite the PNA assay does not allow for the definition of specific mutations, it is the cheapest and easiest screening method to firstly stratify wild-type and mutated patients, information that is strictly necessary to clinicians for the management of CRC and anti-EGFR treatment.

Prognostic and therapeutic impact of argininosuccinate synthetase 1 control in bladder cancer as monitored longitudinally by PET imaging.

Targeted therapies have yet to have significant impact on the survival of patients with bladder cancer. In this study, we focused on the urea cycle enzyme argininosuccinate synthetase 1 (ASS1) as a therapeutic target in bladder cancer, based on our discovery of the prognostic and functional import of ASS1 in this setting. ASS1 expression status in bladder tumors from 183 Caucasian and 295 Asian patients was analyzed, along with its hypothesized prognostic impact and association with clinicopathologic features, including tumor size and invasion. Furthermore, the genetics, biology, and therapeutic implications of ASS1 loss were investigated in urothelial cancer cells. We detected ASS1 negativity in 40% of bladder cancers, in which multivariate analysis indicated worse disease-specific and metastasis-free survival. ASS1 loss secondary to epigenetic silencing was accompanied by increased tumor cell proliferation and invasion, consistent with a tumor-suppressor role for ASS1. In developing a treatment approach, we identified a novel targeted antimetabolite strategy to exploit arginine deprivation with pegylated arginine deiminase (ADI-PEG20) as a therapeutic. ADI-PEG20 was synthetically lethal in ASS1-methylated bladder cells and its exposure was associated with a marked reduction in intracellular levels of thymidine, due to suppression of both uptake and de novo synthesis. We found that thymidine uptake correlated with thymidine kinase-1 protein levels and that thymidine levels were imageable with [(18)F]-fluoro-L-thymidine (FLT)-positron emission tomography (PET). In contrast, inhibition of de novo synthesis was linked to decreased expression of thymidylate synthase and dihydrofolate reductase. Notably, inhibition of de novo synthesis was associated with potentiation of ADI-PEG20 activity by the antifolate drug pemetrexed. Taken together, our findings argue that arginine deprivation combined with antifolates warrants clinical investigation in ASS1-negative urothelial and related cancers, using FLT-PET as an early surrogate marker of response.