Diffuse gliomas in patients aged 55 years or over: A suggestion for IDH mutation testing

Diffuse gliomas are defined on the isocitrate dehydrogenase (IDH) gene (IDH) mutational mutational status. The most frequent IDH mutation is IDH1 R132H, which is detectable by immunohistochemistry; other IDH mutations are rare (10%). IDH mutant gliomas have better prognosis. Further, IDH wild-type low-grade (II/III) gliomas have clinical behaviors similar to those of glioblastoma (GBM) and it was suggested that they are submitted to similar post-surgical treatment. The incidence of IDH mutant gliomas (2%) and that of GBMs with non-canonical IDH mutations (< 1%) are very low in patients ≥ 55 years. For this reason, it was suggested that immunohistochemistry against IDH1 R132H is sufficient to classify GBM as IDH wild-type in this age group. However, no indication was provided for IDH mutational testing in low-grade diffuse gliomas. To address this issue, 273 diffuse gliomas were tested for IDH1 R132H immunohistochemistry. 2/4 diffuse astrocytomas (DAs), 4/9 anaplastic astrocytomas (AAs), 2/256 GBMs, and 4/4 oligodendrogliomas had positive staining. No other IDH mutations were found in immuno-negative low-grade cases by DNA sequencing. To validate our findings, we considered 311 diffuse gliomas in patients ≥ 55 years in The Cancer Genome Atlas database. Fifty-five out of 311 gliomas had IDH R132H mutations (9/16 DAs; 8/48 AAs; 3/211 GBMs; 35/36 oligodendrogliomas), one DA, and one oligodendroglioma had other IDH mutations. IDH mutant gliomas had significantly higher frequency of O-6-methylguanine-DNA methyltransferase promoter methylation (P = 0.0008) and longer overall survival (P < 0.0001). In conclusion, low-grade gliomas are a minor part of gliomas (117/584) in patients ≥ 55 years, albeit they represent most IDH mutant gliomas in this age group (64/69 cases). IDH non-canonical mutations can be found in immunonegative low-grade gliomas (2/54). In view of its significance for prognosis and therapeutic management, our results suggest that IDH mutational status is assessed in all diffuse gliomas in patients ≥ 55 years by immunohistochemistry, followed by IDH sequencing in low-grade immunonegative cases.

Tumor-facing hepatocytes significantly contribute to mild hyperthermia-induced targeting of rat liver metastasis by PLGA-NPs

The effect of mild hyperthermia (MHT) on nanoparticle (NP) accumulation in rat model liver metastasis and the contribution of neoplastic and non-neoplastic cells were characterized. CdSe/ZnS QD-doped poly(lactic-co-glycolic acid) (PLGA) NPs (155 ± 10 nm) were delivered via the ileocolic vein to metastatic livers 15 min after localized MW irradiation (1 min, 41 °C) or in normothermia (37 °C, NT). Quantitative analysis of tissue sections by confocal fluorescence microscopy 1 h after NP injection showed no NP tumor accumulation in NT. On the contrary, MHT increased NP association with tumor, compared to normal tissue. Counterstaining of specific markers showed that the MHT effect is due to an increased NP endocytosis not only by tumor cells, but also by hepatocytes at the growing tumor edge and, to a minor extent, by tumor-associated macrophages. High-NP capturing hepatocytes, close to the tumor, may be a relevant phenomenon in MHT-induced increased targeting of NPs to liver metastasis, influencing their therapeutic efficacy.

Dopamine-derived quinones affect the structure of the redox sensor DJ-1 through modifications at Cys-106 and Cys-53

The physiological role of DJ-1, a protein involved in familial Parkinson disease is still controversial. One of the hypotheses proposed indicates a sensor role for oxidative stress, through oxidation of a conserved cysteine residue (Cys-106). The association of DJ-1 mutations with Parkinson disease suggests a loss of function, specific to dopaminergic neurons. Under oxidative conditions, highly reactive dopamine quinones (DAQs) can be produced, which can modify cysteine residues. In cellular models, DJ-1 was found covalently modified by dopamine. We analyzed the structural modifications induced on human DJ-1 by DAQs in vitro. We described the structural perturbations induced by DAQ adduct formation on each of the three cysteine residues of DJ-1 using specific mutants. Cys-53 is the most reactive residue and forms a covalent dimer also in SH-SY5Y DJ-1-transfected cells, but modification of Cys-106 induces the most severe structural perturbations; Cys-46 is not reactive. The relevance of these covalent modifications to the several functions ascribed to DJ-1 is discussed in the context of the cell response to a dopamine-derived oxidative insult.