Evaluation of mitochondrial stress following ultraviolet radiation and 5G radiofrequency field exposure in human skin cells

Whether human cells are impacted by environmental electromagnetic fields (EMF) is still a matter of debate. With the deployment of the fifth generation (5G) of mobile communication technologies, the carrier frequency is increasing and the human skin becomes the main biological target. Here, we evaluated the impact of 5G-modulated 3.5 GHz radiofrequency (RF) EMF on mitochondrial stress in human fibroblasts and keratinocytes that were exposed for 24 h at specific absorption rate of 0.25, 1, and 4 W/kg. We assessed cell viability, mitochondrial reactive oxygen species (ROS) production, and membrane polarization. Knowing that human skin is the main target of environmental ultraviolet (UV), using the same read-out, we investigated whether subsequent exposure to 5G signal could alter the capacity of UV-B to damage skin cells. We found a statistically significant reduction in mitochondrial ROS concentration in fibroblasts exposed to 5G signal at 1 W/kg. On the contrary, the RF exposure slightly but statistically significantly enhanced the effects of UV-B radiation specifically in keratinocytes at 0.25 and 1 W/kg. No effect was found on mitochondrial membrane potential or apoptosis in any cell types or exposure conditions suggesting that the type and amplitude of the observed effects are very punctual.

Prognostic and Predictive Biomarkers in Head and Neck Squamous Cell Carcinoma Treated with Radiotherapy-A Systematic Review

Background: Radiotherapy is a mainstay in head and neck squamous cell carcinoma (HNSCC) treatment but is mostly applied without stratification by molecular diagnostics. Development of reliable biomarkers may have the potential to improve radiotherapy (RT) efficacy and reduce toxicity. We conducted a systematic review to summarize the field of biomarkers in HNSCC treated by RT. Methods: Pubmed and EMBASE were searched independently by two researchers following pre-defined inclusion and exclusion criteria. Z curves were generated to investigate publication bias. OncoKB was used for identification of druggable targets. Results: 134 manuscripts remained for data extraction. 12% of tumors were AJCC/UICC stage I-II and 82% were stage III-IV. The most common biomarkers were proteins (39%), DNA (14%) and mRNA (9%). Limiting analysis to prospective data and statistically significant results, we found three potentially druggable targets: ERCC2, PTCH1 and EGFR. Regarding data quality, AJCC/UICC stage was missing in 32% of manuscripts. 73% of studies were retrospective and only 7% were based on prospective randomized trials. Z-curves indicated the presence of publication bias. Conclusion: An abundance of potential biomarkers in HNSCC is available but data quality is limited by retrospective collection, lack of validation and publication bias. Improved study design and reporting quality might accelerate successful development of personalized treatments in HNSCC.

Biodegradable Ultrasmall-in-Nano Architectures Loaded with Cisplatin Prodrug in Combination with Ionizing Radiation Induces DNA Damage and Apoptosis in Pancreatic Ductal Adenocarcinoma

Considering the dismal survival rate, novel therapeutic strategies are warranted to improve the outcome of pancreatic ductal adenocarcinoma (PDAC). Combining nanotechnology for delivery of chemotherapeutics-preferably radiosensitizing agents-is a promising approach to enhance the therapeutic efficacy of chemoradiation. We assessed the effect of biodegradable ultrasmall-in-nano architectures (NAs) containing gold ultra-small nanoparticles (USNPs) enclosed in silica shells loaded with cisplatin prodrug (NAs-cisPt) combined with ionizing radiation (IR). The cytotoxic effects and DNA damage induction were evaluated in PDAC cell lines (MIA PaCa2, SUIT2-028) and primary culture (PDAC3) in vitro and in the chorioallantoic membrane (CAM) in ovo model. Unlike NAs, NAs-cisPt affected the cell viability in MIA PaCa2 and SUIT2-028 cells. Furthermore, NAs-cisPt showed increased γH2AX expression up to 24 h post-IR and reduced β-globin amplifications resulting in apoptosis induction at DNA and protein levels. Similarly, combined treatment of NAs-cisPt + IR in PDAC3 and SUIT2-028 CAM models showed enhanced DNA damage and apoptosis leading to tumor growth delay. Our results demonstrate an increased cytotoxic effect of NAs-cisPt, particularly through its release of the cisplatin prodrug. As cisplatin is a well-known radiosensitizer, administration of cisplatin prodrug in a controlled fashion through encapsulation is a promising new treatment approach which merits further investigation in combination with other radiosensitizing agents.

The Association of Single-Nucleotide Polymorphism rs13181 in ERCC2 with Risk and Prognosis of Nasopharyngeal Carcinoma in an Endemic Chinese Population

Objective

We examined whether the single-nucleotide polymorphism (SNP) rs13181 in the gene encoding excision repair cross complementation group 2 (ERCC2) is associated with the risk and prognosis of nasopharyngeal carcinoma (NPC).

Methods

SNPs at rs13181 were genotyped in 439 NPC patients (NPC group) and 431 age- and gender-matched cancer-free controls (control group) from a region of China where NPC is endemic, and frequencies of GG, GT and TT genotypes were compared between the two groups in the case–control study. In a subset of 365 NPC cases, SNPs were examined for potential correlation with tumor-free survival time (TFS) and overall survival (OS).

Results

Relative to NPC risk with a TT genotype, NPC risk was similar with GT + GG genotypes (OR 1.052, 95% CI 0.656–1.688), after adjusting for gender, age, smoking history, and immunoglobin A against Epstein-Barr virus capsid antigen (EBV-VCA-IgA) status. Univariate analysis showed that the GG or GT genotype was associated with significantly worse TFS (p<0.001) and OS (p=0.010) than the TT genotype. Prognosis was significantly worse for men than for women (TFS, p=0.045; OS, p=0.031), for T3–T4 classification than for T1–T2 (TFS, p=0.009; OS, p=0.007), for N3 than for N0+N1+N2 (TFS, p<0.001; OS, p<0.001). Based on multivariate analysis, independent risk factors for poor TFS were GG or GT genotype (HR 2.629, 95% CI 1.625–4.254, p<0.001), T3–T4 classification (HR 2.146, 95% CI 1.244–3.701, p=0.006) and N3 (HR 2.527, 95% CI 1.574–4.059, p<0.001). GG or GT genotype (HR 2.217, 95% CI 1.283–3.832, p=0.004), gender (HR 1.989, 95% CI 1.046–3.785, p=0.036), T3–T4 (HR 2.431, 95% CI 1.306–4.526, p=0.005) and N3 (HR 2.693, 95% CI 1.637–4.432, p<0.001) were independent risk factors for poor OS.

Conclusion

The rs13181 SNP in ERCC2 does not appear to be associated with NPC risk, but it may serve as an independent prognostic factor for NPC recurrence and death.

ERCC2 gene single-nucleotide polymorphism as a prognostic factor for locally advanced head and neck carcinomas after definitive cisplatin-based radiochemotherapy

Identifying patients with locally advanced head and neck carcinoma on high risk of recurrence after definitive concurrent radiochemotherapy is of key importance for the selection for consolidation therapy and for individualized treatment intensification. In this multicenter study we analyzed recurrence-associated single-nucleotide polymorphisms (SNPs) in DNA repair genes in tumor DNA from 132 patients with locally advanced head and neck carcinoma (LadHnSCC). Patients were treated with definitive radiotherapy and simultaneous cisplatin-based chemotherapy at six partner sites of the German Cancer Consortium (DKTK) Radiation Oncology Group from 2005 to 2011. For validation, a group of 20 patients was available. Score selection method using proportional hazard analysis and leave-one-out cross-validation were performed to identify markers associated with outcome. The SNPs rs1799793 and rs13181 were associated with survival and the same SNPs and in addition rs17655 with freedom from loco-regional relapse (ffLRR) in the trainings datasets from all patients. The homozygote major rs1799793 genotype at the ERCC2 gene was associated with better (Hazard ratio (HR): 0.418 (0.234-0.744), p = 0.003) and the homozygote minor rs13181 genotype at ERCC2 with worse survival (HR: 2.074, 95% CI (1.177-3.658), p = 0.017) in comparison to the other genotypes. At the ffLRR endpoint, rs1799793 and rs13181 had comparable prognostic value. The rs1799793 and rs13181 genotypes passed the leave-one-out cross-validation procedure and associated with survival and ffLRR in patients with LadHnSCC treated with definitive radiochemotherapy. While findings were confirmed in a small validation dataset, further validation is underway within a prospective biomarker study of the DKTK.

Hypoxia and Noncoding RNAs in Taxane Resistance

Taxanes are chemotherapeutic drugs employed in the clinic to treat a variety of malignancies. Despite their overall efficacy, cancer cells often display resistance to taxanes. Therefore, new strategies to increase the effectiveness of taxane-based chemotherapeutics are urgently needed. Multiple molecular players are linked to taxane resistance; these include efflux pumps, DNA repair mechanisms, and hypoxia-related pathways. In addition, emerging evidence indicates that both non-coding RNAs and epigenetic effectors might also be implicated in taxane resistance. Here we focus on the causes of taxane resistance, with the aim to envisage an integrated model of the 'taxane resistance phenome'. This model could help the development of novel therapeutic strategies to treat taxane-resistant neoplasms.

XPD-The Lynchpin of NER: Molecule, Gene, Polymorphisms, and Role in Colorectal Carcinogenesis

In mammals the bulky DNA adduct lesions known to result in deleterious phenotypes are acted upon and removed from the genomic DNA by nucleotide excision repair (NER) pathway. TFIIH multi-protein complex with its important helicase–Xeroderma Pigmentosum Protein (XPD) serves as the pivotal factor for opening up of the damaged lesion DNA site and carry out the repair process. The initial damage verification step of the TFIIH is in part dependent upon the helicase activity of XPD. Besides, XPD is also actively involved in the initiation steps of transcription and in the regulation of the cell cycle and apoptosis. In this review, we will be exploring the new insights in scientific research on the functioning of the NER pathway, the role of TFIIH as the central complex of NER, the pivotal helicase XPD as the lynchpin of NER and the effects of various single nucleotide polymorphisms (SNPs) of XPD on its functioning and their consequent role in colorectal carcinogenesis.

ERCC2/XPD Lys751Gln alter DNA repair efficiency of platinum-induced DNA damage through P53 pathway

Platinum-based treatment causes Pt-DNA adducts which lead to cell death. The platinum-induced DNA damage is recognized and repaired by the nucleotide excision repair (NER) system of which ERCC2/XPD is a critical enzyme. Single nucleotide polymorphisms in ERCC2/XPD have been found to be associated with platinum resistance. The aim of the present study was to investigate whether ERCC2/XPD Lys751Gln (rs13181) polymorphism is causally related to DNA repair capacity of platinum-induced DNA damage. First, cDNA clones expressing different genotypes of the polymorphism was transfected to an ERCC2/XPD defective CHO cell line (UV5). Second, all cells were treated with cisplatin. Cellular survival rate were investigated by MTT growth inhibition assay, DNA damage levels were investigated by comet assay and RAD51 staining. The distribution of cell cycle and the change of apoptosis rates were detected by a flow cytometric method (FCM). Finally, P53mRNA and phospho-P53 protein levels were further investigated in order to explore a possible explanation. As expected, there was a significantly increased in viability of UV5^{ERCC2 (AA)} as compared to UV5^{ERCC2 (CC)} after cisplatin treatment. The DNA damage level of UV5^{ERCC2 (AA)} was significant decreased compared to UV5^{ERCC2 (CC)} at 24 h of treatment. Mutation of ERCC2rs13181 AA to CC causes a prolonged S phase in cell cycle. UV5^{ERCC2 (AA)} alleviated the apoptosis compared to UV5^{ERCC2 (CC)}, meanwhile P53mRNA levels in UV^{ERCC2 (AA)} was also lower when compared UV5^{ERCC2 (CC)}. It co-incides with a prolonged high expression of phospho-P53, which is relevant for cell cycle regulation, apoptosis, and the DNA damage response (DDR). We concluded that ERCC2/XPD rs13181 polymorphism is possibly related to the DNA repair capacity of platinum-induced DNA damage. This functional study provides some clues to clarify the relationship between cisplatin resistance and ERCC2/XPDrs13181 polymorphism.

On the use of pharmacogenetics in cancer treatment and clinical trials

There are an increasing number of studies devoted to the identification of associations between anticancer drug efficacy and toxicity and common polymorphisms present in the patients' genome. However, many articles presenting the results of such studies do not bring the simple and necessary background information allowing the evaluation of the relevance of the study, its significance and its potential importance for patients' treatment. This position paper first addresses clinical oncologists with the aim of giving them the basic knowledge on pharmacogenetics and on the potential use of gene polymorphisms as predictive biomarkers in routine and clinical research. A secondary objective is to give molecular biologists some recommendations on how to conceive protocols and how to publish their results when they develop pharmacogenetic studies appended to clinical trials or with autonomous goals.

Association between ERCC2 polymorphisms and glioma risk: a meta-analysis

ERCC2 is an essential component of the nucleotide excision repair pathway which is involved in the effective maintenance of genome integrity. Association studies on ERCC2 polymorphisms and glioma risk have yielded inconclusive results. This meta-analysis was performed to gain a better insight into the relationship between ERCC2 polymorphisms and glioma risk. A systematic literature search updated to December 2, 2013 was performed in the Pubmed and EMBASE databases. Crude pooled odds ratios (ORs) with their corresponding 95% confidence intervals (95% CIs) were used to estimate the association between ERCC2 polymorphisms and glioma risk under a suitable effect model according to heterogeneity. All analyses were performed using Review Manager 5 (version 5.2) and STATA (version 12.0). The combined results demonstrated rs13181 to be significantly associated with glioma risk (G allele versus T allele: OR=1.15, 95% CI=1.05-1.26, P=0.002; dominant model: OR=1.22, 95% CI=1.07-1.39, P=0.002; recessive model: OR=1.18, 95% CI=0.98-1.41, P=0.070). We also found that rs13181 acts in an allele dose-dependent manner (GG versus TT: OR=1.30, 95% CI=1.07-1.57, P=0.009; TG versus TT: OR=1.20, 95%=CI 1.05-1.37, P=0.009; trend test, P=0.004). However, no evidence was found in analyses for the association between other 3 ERCC2 polymorphisms (rs238406, rs1799793, and rs1052555) and susceptibility to glioma development. Our meta-analysis suggests that rs13181 is significantly associated with glioma risk in an allele dose-dependent manner, whereas, 3 other ERCC2 polymorphisms (rs238406, rs1799793, and rs1052555) may have no influence.

No association between XRCC3 Thr241Met and XPD Lys751Gln polymorphisms and the risk of colorectal cancer in West Algerian population: a case-control study

Colorectal cancer (CRC) is a complex and multifactorial disease, in which genetic and environmental factors both seem to play a part. Many epidemiological studies have explored the association between genetic polymorphisms of X-ray repair cross-complementing group 3 (XRCC3) (Thr241Met) and Xeroderma pigmentosum group D (XPD) lysine to glutamine at codon 751 (Lys751Gln) and risk of CRC in various populations; however, the results are controversial. We conducted this case-control study in a West Algerian population to assess the potential role of this genetic polymorphism on the risk of CRC in this population. Genomic DNA was extracted from blood samples collected from 129 sporadic CRC patients and 148 normal controls. The polymorphisms were determined by pyrosequencing technique. The distribution of XRCC3 Thr241Met and XPD Lys751Gln genotypes among controls did not differ significantly from those predicted by the Hardy-Weinberg distribution (p > 0.05). There were no significant differences in the genotypes distribution and allele frequencies between CRC patients and controls. A significant association was found between the combined heterozygous of XRCC3 and homozygous variant of XPD gene and CRC. This is the first study on DNA repair genetic polymorphisms in West Algerian population, and it suggests that the XRCC3 Thr241Met and XPD Lys751Gln polymorphisms may not be associated with the CRC risk in this population.