Rhodiola rosea extract protects human cortical neurons against glutamate and hydrogen peroxide-induced cell death through reduction in the accumulation of intracellular calcium

The aim of this study was to investigate the neuroprotective effects of a titolated extract from Rhodiola rosea L. (RrE) and of salidroside (Sa), one of the major biologically active compounds extracted from this medicinal plant, against oxidative stressor hydrogen peroxide (H₂O₂) and glutamate (GLU)‐induced cell apoptosis in a human cortical cell line (HCN 1‐A) maintained in culture. The results obtained indicate that exposure of differentiated HCN 1‐A neurons to GLU or H₂O₂ resulted in concentration‐dependent cell death. A 24 h pre‐treatment with RrE significantly increased cell survival and significantly prevented the plasma membrane damage and the morphological disruption caused by GLU or H₂O₂, indicating that neurons treated with RrE were protected from the neurotoxicity induced by the oxidative stressor used. In addition, RrE significantly reduced H₂O₂ or GLU‐induced elevation of intracellular free Ca²⁺ concentration. The results obtained have also shown that Sa caused similar effects in all experimental models used; however, the potency of the action was lower than that of the extract containing corresponding quantities of Sa. These findings indicate that RrE has a neuroprotective effect in cortical neurons and suggest that the antioxidant activity of the RrE, due to the structural features of the synergic active principles they contain, may be responsible for its ability to stabilize cellular Ca²⁺ homeostasis. Copyright © 2011 John Wiley & Sons, Ltd.     

Clinical impact of anti-epidermal growth factor receptor monoclonal antibodies in first-line treatment of metastatic colorectal cancer: meta-analytical estimation and implications for therapeutic strategies

BACKGROUND:

Antiepidermal growth factor receptor (anti‐EGFR) monoclonal antibodies (MoAbs) are indicated for the treatment of metastatic colorectal cancer patients, but some scientific issues concerning their efficacy are currently unsolved.

METHODS:

A literature‐based meta‐analysis was conducted. Hazard ratios (HRs) were extracted from randomized trials for progression‐free survival (PFS) and overall survival (OS); the event‐based risk ratio was derived for response. Sensitivity analyses to look for interactions according to KRAS status and chemotherapy association regimens were performed.

RESULTS:

Eight trials (6609 patients) were identified. A significant interaction according to KRAS status was found for PFS (wild type vs mutant, P = .001) and response rate (wild type vs mutant, P < .0001). The addition of an anti‐EGFR MoAb to first‐line chemotherapy increased PFS in the KRAS wild‐type population (HR, 0.91; 95% confidence interval [CI], 0.84‐0.99; P = .03), and had a detrimental effect in the KRAS mutant population (HR, 1.13; 95% CI, 1.03‐1.25; P = .013). A significant increase in the probability of achieving a response was evident in KRAS wild‐type patients (relative risk, 1.17; 95% CI, 1.04‐1.33; P = .011). In this population, the interaction in response rate according to adopted chemotherapy favored irinotecan‐containing regimens (P = .01), and at meta‐regression analysis the relative increase in response rate was significantly related to PFS (P = .00001) and OS (P = .00193) benefit.

CONCLUSIONS:

The addition of an anti‐EGFR MoAb to first‐line chemotherapy produces a clear benefit in response rate. This advantage is restricted to KRAS wild‐type patients and translates into a small benefit in PFS. At present, irinotecan‐based backbone chemotherapy could be a preferable option. The correlation between activity and survival parameters corroborates the hypothesis that anti‐EGFR MoAbs might be more suitable for patients needing tumoral shrinkage. Cancer 2011;. © 2011 American Cancer Society.     

Family history of cancer and the risk of laryngeal cancer: a case-control study from Italy and Switzerland

Only limited data is available on the relationship between family history of laryngeal and other neoplasms and laryngeal cancer risk. We investigated the issue using data from a multicentre case-control study conducted in Italy and Switzerland between 1992 and 2009 including 852 cases with histologically confirmed laryngeal cancer and 1970 controls admitted to hospital for acute, non neoplastic conditions. Unconditional logistic regression models adjusted for age, sex, study center, education, tobacco smoking, alcohol drinking and number of siblings were used to estimate the odds ratios (ORs) of laryngeal cancer. The multivariate OR was 2.8 (95% confidence interval [CI], 1.5-5.3) in subjects reporting a first-degree relative with laryngeal cancer, as compared to subjects with no family history. The OR was higher when the relative was diagnosed before 60 years of age (OR = 3.5, 95% CI 1.4-8.8). As compared to subjects without family history, non-smokers, and moderate drinkers, the OR was 37.1 (95% CI 9.9-139.4) for current smokers, heavy drinkers, with family history of laryngeal cancer. Family history of colorectal (OR = 1.5, 95% CI 1.0-2.3) and kidney (OR = 3.8, 95% CI 1.2-12.1) cancer were also associated to an increased risk of laryngeal cancer, while no significant increase in risk was found for family history of cancer at all sites, excluding the larynx (OR = 1.1).     

The role of MTHFR and RFC1 polymorphisms on toxicity and outcome of adult patients with hematological malignancies treated with high-dose methotrexate followed by leucovorin rescue

Purpose

In the last years, the influence of different genes involved in metabolism of chemotherapeutic agents has been studied. Methotrexate (MTX) is a key compound of chemotherapeutic regimens used in the treatment of acute lymphoblastic leukemia (ALL), primary central nervous system lymphoma (PCNSL) and Burkitt??s lymphomas (BL). This study aims to evaluate the role of MTHFR C677T and A1298C polymorphisms and G80A reduced folate carrier gene (RFC1) in a cohort of adult patients with lymphoproliferative malignancies submitted to high-dose MTX followed by leucovorin rescue.

Methods

We performed the analysis of these polymorphisms on genomic DNA with RFLP?CPCR.

Results

Patients carrying MTHFR A1298C variant showed decreased hepatic and hematological toxicity (P?=?0.03). Overall survival (OS) and progression-free survival (PFS) between homozygous wild-type and variant patients for the RFC1 G₈₀A were significantly different (P?=?0.035 and P?=?0.02, respectively). A significant correlation between hematological toxicity and age (P?=?0.003) was observed. There was no significant influence of MTHFR C677T genotype on toxicity, OS and PFS.

Conclusions

Leucovorin rescue given after high-dose MTX probably accounts for the lack of influence of C677T polymorphism. To better define a role of RFC1 polymorphism on patients outcome, it would be worthwhile to perform a study on intracellular MTX level and RFC1 substrate binding affinities in different genotypes.     

Preclinical evaluation of the novel 7-substituted camptothecin Namitecan (ST1968) in paediatric tumour models

Purpose

The present study aimed to evaluate the new water soluble camptothecin analogue Namitecan (ST1968) in preclinical paediatric tumour models of the nervous system comprehensive of neuroblastoma, primitive neuroectodermal tumours/PNET and medulloblastoma where the drug was compared to Irinotecan.

Methods

Cellular sensitivity to the drug was assessed by MTT and clonogenic assays. Propidium iodide staining was used for cell cycle perturbation studies. The genotoxic effects were quantified by Comet assay, whereas apoptosis was assessed by PARP cleavage and sub-G1 accumulation. Tumour response was investigated in xenograft models in nude mice.

Results

The cellular response to Namitecan was heterogeneous with IC₅₀ (2?h) ranging between 0.14 and 13.26???M, whereas SN38 (the active metabolite of Irinotecan) appeared more effective (IC₅₀: 0.03?C11.7???M). Interestingly, prolonged drug incubation times up to 72?h enhanced Namitecan cytotoxicity, with similar colony inhibition curves between the two analogues (IC₅₀, nM-SN38: 0.9?±?0.2; Namitecan: 0.7?±?0.4). DNA damage, accumulation in late-S/G2 phases and induction of apoptosis appeared important players of Namitecan cytotoxicity in our models. In vivo, Namitecan was superior to Irinotecan in three out of five xenograft models, with reversible weight loss (10?%). In the sensitive SK-N-AS xenograft, Namitecan showed a high retention in tumours consistently with: high antitumour response, rapid drug-mediated DNA damage (60?% mean TailDNA after 1?h from drug inoculation), persistent cell cycle perturbation (60?C40?% G2 accumulation after 48?C72?h, respectively) and apoptosis. Studies with Namitecan and platinum agents in this model showed a significant enhancement of antitumour activity of the drugs combination versus single agents.

Conclusions

Our preclinical data strongly support the interest of further investigations on the well-tolerated Namitecan either as a single agent or in combination in paediatric oncology.     

Mitochondrial fission induces glycolytic reprogramming in cancer-associated myofibroblasts, driving stromal lactate production, and early tumor growth

Recent studies have suggested that cancer cells behave as metabolic parasites, by inducing oxidative stress in adjacent normal fibroblasts. More specifically, oncogenic mutations in cancer cells lead to ROS production and the "secretion" of hydrogen peroxide species. Oxidative stress in stromal fibroblasts then induces their metabolic conversion into cancer-associated fibroblasts. Such oxidative stress drives the onset of autophagy, mitophagy, and aerobic glycolysis in fibroblasts, resulting in the local production of high-energy mitochondrial fuels (such as L-lactate, ketone bodies, and glutamine). These recycled nutrients are then transferred to cancer cells, where they are efficiently burned via oxidative mitochondrial metabolism (OXPHOS). We have termed this new energy-transfer mechanism "Two-Compartment Tumor Metabolism", to reflect that the production and consumption of nutrients (L-lactate and other catabolites) is highly compartmentalized. Thus, high-energy onco-catabolites are produced by the tumor stroma. Here, we used a genetic approach to stringently test this energy-transfer hypothesis. First, we generated hTERT-immortalized fibroblasts which were genetically re-programmed towards catabolic metabolism. Metabolic re-programming towards glycolytic metabolism was achieved by the recombinant over-expression of MFF (mitochondrial fission factor). MFF over-expression results in extensive mitochondrial fragmentation, driving mitochondrial dysfunction. Our results directly show that MFFfibroblasts undergo oxidative stress, with increased ROS production, and the onset of autophagy and mitophagy, both catabolic processes. Mechanistically, oxidative stress induces autophagy via NF-kB activation, also providing a link with inflammation. As a consequence MFF-fibroblasts showed intracellular ATP depletion and the extracellular secretion of L-lactate, a critical onco-catabolite. MFF-fibroblasts also showed signs of myofibroblast differentiation, with the expression of SMA and calponin. Importantly, MFF-fibroblasts signficantly promoted early tumor growth (up to 6.5-fold), despite a 20% overall reduction in angiogenesis. Thus, catabolic metabolism in cancer-associated fibroblasts may be a critical event during tumor intiation, allowing accelerated tumor growth, especially prior to the onset of neoangiogenesis.     

Will Hsp90 inhibitors prove effective in BRAF-mutant melanomas?

The RAF inhibitor vemurafenib has unprecedented activity in BRAF-mutant melanomas, but resistance invariably develops. As Hsp90 is required for the stability of several of the oncoproteins that mediate RAF inhibitor resistance, inhibitors of this cellular chaperone may be effective in patients with intrinsic or acquired resistance to RAF inhibitors.