The antioxidant function of Bcl-2 preserves cytoskeletal stability of cells with defective respiratory complex I.

Human thyroid carcinoma XTC.UC1 cells harbor a homoplasmic frameshift mutation in the MT-ND1 subunit of respiratory complex I. When forced to use exclusively oxidative phosphorylation for energy production by inhibiting glycolysis, these cells triggered a caspase-independent cell death pathway, which was associated to a significant imbalance in glutathione homeostasis and a cleavage of the actin cytoskeleton. Overexpression of the anti-apoptotic Bcl-2 protein significantly increased the level of endogenous reduced glutathione, thus preventing its oxidation after the metabolic stress. Furthermore, Bcl-2 completely inhibited actin cleavage and increased cell adhesion, but was unable to improve cellular viability. Similar effects were obtained when XTC.UC1 cells were incubated with exogenous glutathione. We hence propose that Bcl-2 can safeguard cytoskeletal stability through an antioxidant function.

Rare mtDNA variants in Leber hereditary optic neuropathy families with recurrence of myoclonus.

OBJECTIVE: To investigate the mechanisms underlying myoclonus in Leber hereditary optic neuropathy (LHON). METHODS: Five patients and one unaffected carrier from two Italian families bearing the homoplasmic 11778/ND4 and 3460/ND1 mutations underwent a uniform investigation including neurophysiologic studies, muscle biopsy, serum lactic acid after exercise, and muscle ((31)P) and cerebral ((1)H) magnetic resonance spectroscopy (MRS). Biochemical investigations on fibroblasts and complete mitochondrial DNA (mtDNA) sequences of both families were also performed. RESULTS: All six individuals had myoclonus. In spite of a normal EEG background and the absence of giant SEPs and C reflex, EEG-EMG back-averaging showed a preceding jerk-locked EEG potential, consistent with a cortical generator of the myoclonus. Specific comorbidities in the 11778/ND4 family included muscular cramps and psychiatric disorders, whereas features common to both families were migraine and cardiologic abnormalities. Signs of mitochondrial proliferation were seen in muscle biopsies and lactic acid elevation was observed in four of six patients. (31)P-MRS was abnormal in five of six patients and (1)H-MRS showed ventricular accumulation of lactic acid in three of six patients. Fibroblast ATP depletion was evident at 48 hours incubation with galactose in LHON/myoclonus patients. Sequence analysis revealed haplogroup T2 (11778/ND4 family) and U4a (3460/ND1 family) mtDNAs. A functional role for the non-synonymous 4136A>G/ND1, 9139G>A/ATPase6, and 15773G>A/cyt b variants was supported by amino acid conservation analysis. CONCLUSIONS: Myoclonus and other comorbidities characterized our Leber hereditary optic neuropathy (LHON) families. Functional investigations disclosed a bioenergetic impairment in all individuals. Our sequence analysis suggests that the LHON plus phenotype in our cases may relate to the synergic role of mtDNA variants.

Concerted escalation of dose and dosing duration in a phase I study of the oral camptothecin gimatecan (ST1481) in patients with advanced solid tumors.

BACKGROUND: Gimatecan is an orally bioavailable camptothecin analogue with preclinical findings of promising antitumor activity. A phase I design of concerted dose escalation and dosing duration was implemented to assess the potential schedule dependency of tolerability that emerged from animal studies. PATIENTS AND METHODS: Gimatecan was given daily for five consecutive days per week for 1, 2 or 3 weeks every 28 days. Plasma levels of total gimatecan were measured on the first and the last day of treatment in each schedule. RESULTS: Overall, 108 patients were treated with 0.8-7.2 mg/m(2) of gimatecan per cycle. The main toxicity was myelosuppression with dose-limiting thrombocytopenia. In the 1-, 2- and 3-week schedule, the maximum tolerated doses were 4.5, 5.6 and 6.4 mg/m(2). Diarrhea and asthenia were of low grade and of minor clinical relevance, while the higher incidence of nausea and vomiting in the 1-week schedule required the use of antiemetic prophylaxis. Due to the prolonged half-life (approximately 77 h), the plasma concentration of gimatecan increased from the first to the last day of dosing. Six partial responses were observed. CONCLUSIONS: Tolerability of gimatecan was schedule dependent. Further testing with schedules taking into account its long persistence in human plasma is worthwhile.

Caspase-independent death of Leber's hereditary optic neuropathy cybrids is driven by energetic failure and mediated by AIF and Endonuclease G.

Leber's hereditary optic neuropathy (LHON) is associated with mitochondrial DNA point mutations affecting different subunits of complex I. By replacing glucose with galactose in the medium, cybrids harboring each of the three LHON pathogenic mutations (11778/ND4, 3460/ND1, 14484/ND6) suffered a profound ATP depletion over a few hours and underwent apoptotic cell death, which was caspase-independent. Control cybrids were unaffected. In addition to cytochrome c, apoptosis inducing factor (AIF) and endonuclease G (EndoG) were also released from the mitochondria into the cytosol in LHON cybrids, but not in control cells. Exposure of isolated nuclei to cytosolic fractions from LHON cybrids maintained in galactose medium caused nuclear fragmentation, which was strongly reduced by immuno-depletion with anti-AIF and anti-EndoG antibodies. In conclusion, the caspase-independent death of LHON cybrids incubated in galactose medium is triggered by rapid ATP depletion and mediated by AIF and EndoG.

Early predictors of peripheral neurotoxicity in cisplatin and paclitaxel combination chemotherapy.

BACKGROUND: We investigated the possible use of clinical signs of chemotherapy-induced peripheral neurotoxicity (CIPN) or of nerve growth factor (NGF) circulating levels to predict the final outcome of CIPN. PATIENTS AND METHODS: Sixty-two women affected by locally advanced squamous cervical carcinoma treated with TP (paclitaxel 175 mg/m2 over a 3 h infusion plus cisplatin 75 mg/m2) or TIP (TP plus ifosphamide 5 mg/m2) were examined and scored according to the Total Neuropathy Score (TNS), before and during chemotherapy. RESULTS: A correlation with the final severity of CIPN was observed with vibration perception and deep tendon reflex evaluation, while pin sensibility, strength, and autonomic symptoms and signs were not informative. A highly significant correlation existed between the decrease in circulating levels of NGF and the severity of CIPN (r = -0.579; P < 0.001; 95% confidence limits -0.702 to -0.423). However, circulating levels of NGF were not effective as predictors of the final neurological outcome of each patient. CONCLUSION: Our study indicates that a precise clinical evaluation of the peripheral nervous system of patients treated with platinum and taxane combination polychemotherapy not only gives reliable information regarding the course of CIPN, but also can be used to predict the final neurological outcome of the treatment.

Grading of chemotherapy-induced peripheral neurotoxicity using the Total Neuropathy Scale.

The authors compared clinically based neurotoxicity scales with the Total Neuropathy Scale, with the aim of improving the grading of the severity of chemotherapy-induced peripheral neuropathy (CIPN). The severity of CIPN was evaluated in a series of 60 women treated with cisplatin- and paclitaxel-based chemotherapy. A reduced version of TNS (TNSr) was also compared. The authors concluded that the TNS and TNSr can be used to assess the severity of CIPN effectively, and the results of this evaluation can be reliably correlated with the oncologic grading of sensory peripheral neurotoxicity.

Clinical value of CA 19-9 (carbohydrate antigen) in gastrointestinal adenocarcinoma.

CA 19-9 and CEA serum levels were determined before and 7 days after surgery in 140 patients with gastrointestinal adenocarcinoma, and in 70 patients with gastrointestinal non neoplastic diseases. CA 19-9 test was shown to be positive in 37.9% of colorectal cancer, in 32.6% of gastric cancer and in 77.8% of pancreatic cancer. CA 19-9 test was also shown to be more sensitive for colonic cancer with respect to rectal cancer (40.9% vs. 23.5%). CA 19-9 test is more sensitive and specific than CEA. In particular, the reported results suggest the clinical value of CA 19-9 test in the diagnosis of pancreatic adenocarcinoma and as a suitable parameter in the follow-up of gastrointestinal cancer.