Melatonin mediates elevated carbon dioxide-induced photosynthesis and thermotolerance in tomato.

Increasing carbon dioxide (CO2 ) promotes photosynthesis and mitigates heat stress-induced deleterious effects on plants, but the regulatory mechanisms remain largely unknown. Here, we found that tomato (Solanum lycopersicum L.) plants treated with high atmospheric CO2 concentrations (600, 800, and 1000 µmol mol-1 ) accumulated increased levels of melatonin (N-acetyl-5-methoxy tryptamine) in their leaves and this response is conserved across many plant species, including Arabidopsis, rice, wheat, mustard, cucumber, watermelon, melon, and hot pepper. Elevated CO2 (eCO2 ; 800 µmol mol-1 ) caused a 6.8-fold increase in leaf melatonin content, and eCO2 -induced melatonin biosynthesis preferentially occurred through chloroplast biosynthetic pathways in tomato plants. Crucially, manipulation of endogenous melatonin levels by genetic means affected the eCO2 -induced accumulation of sugar and starch in tomato leaves. Furthermore, net photosynthetic rate, maximum photochemical efficiency of photosystem II, and transcript levels of chloroplast- and nuclear-encoded photosynthetic genes, such as rbcL, rbcS, rbcA, psaD, petB, and atpA, significantly increased in COMT1 overexpressing (COMT1-OE) tomato plants, but not in melatonin-deficient comt1 mutants at eCO2 conditions. While eCO2 enhanced plant tolerance to heat stress (42°C) in wild-type and COMT1-OE, melatonin deficiency compromised eCO2 -induced thermotolerance in comt1 plants. The expression of heat shock proteins genes increased in COMT1-OE but not in comt1 plants in response to eCO2 under heat stress. Further analysis revealed that eCO2 -induced thermotolerance was closely linked to the melatonin-dependent regulation of reactive oxygen species, redox homeostasis, cellular protein protection, and phytohormone metabolism. This study unveiled a crucial mechanism of elevated CO2 -induced thermotolerance in which melatonin acts as an essential endogenous signaling molecule in tomato plants.

HsfA1a confers pollen thermotolerance through upregulating antioxidant capacity, protein repair, and degradation in Solanum lycopersicum L.

The heat shock transcription factors (Hsfs) play critical roles in plant responses to abiotic stresses. However, the mechanism of Hsfs in the regulation of pollen thermotolerance and their specific biological functions and signaling remain unclear. Herein, we demonstrate that HsfA1a played a key role in tomato pollen thermotolerance. Pollen thermotolerance was reduced in hsfA1a mutants but was increased by hsfA1a overexpression, based on pollen viability and germination. Analyzing the whole transcriptome by RNA-seq data, we found that HsfA1a mainly regulated the genes involved in oxidative stress protection, protein homeostasis regulation and protein modification, as well as the response to biological stress in anthers under heat stress. The accumulation of reactive oxygen species in anthers was enhanced in hsfA1a mutants but decreased in HsfA1a-overexpressing lines. Furthermore, HsfA1a bound to the promoter region of genes involved in redox regulation (Cu/Zn-SOD, GST8, and MDAR1), protein repair (HSP17.6A, HSP70-2, HSP90-2, and HSP101) and degradation (UBP5, UBP18, RPN10a, and ATG10) and regulated the expression of these genes in tomato anthers under heat stress. Our findings suggest that HsfA1a maintains pollen thermotolerance and cellular homeostasis by enhancing antioxidant capacity and protein repair and degradation, ultimately improving pollen viability and fertility.

The E3 Ubiquitin Ligase Gene Sl1 Is Critical for Cadmium Tolerance in Solanum lycopersicum L.

Heavy metal cadmium (Cd) at high concentrations severely disturbs plant growth and development. The E3 ubiquitin ligase involved in protein degradation is critical for plant tolerance to abiotic stress, but the role of E3 ubiquitin ligases in Cd tolerance is largely unknown in tomato. Here, we characterized an E3 ubiquitin ligase gene Sl1, which was highly expressed in roots under Cd stress in our previous study. The subcellular localization of Sl1 revealed that it was located in plasma membranes. In vitro ubiquitination assays confirmed that Sl1 had E3 ubiquitin ligase activity. Knockout of the Sl1 gene by CRISPR/Cas9 genome editing technology reduced while its overexpression increased Cd tolerance as reflected by the changes in the actual quantum efficiency of PSII photochemistry (ΦPSII) and hydrogen peroxide (H2O2) accumulation. Cd-induced increased activities of antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were compromised in sl1 mutants but were enhanced in Sl1 overexpressing lines. Furthermore, the content of Cd in both shoots and roots increased in sl1 mutants while reduced in Sl1 overexpressing plants. Gene expression assays revealed that Sl1 regulated the transcript levels of heavy metal transport-related genes to inhibit Cd accumulation. These findings demonstrate that Sl1 plays a critical role in regulating Cd tolerance by relieving oxidative stress and resisting heavy metal transportation in tomato. The study provides a new understanding of the mechanism of plant tolerance to heavy metal stress.

Development of a Nomogram Model for Treatment of Elderly Patients with Locoregionally Advanced Nasopharyngeal Carcinoma.

(1) Purpose: This study aims to explore risk-adapted treatment for elderly patients with locoregionally advanced nasopharyngeal carcinoma (LA-NPC) according to their pretreatment risk stratification and the degree of comorbidity. (2) Methods: A total of 583 elderly LA-NPC patients diagnosed from January 2011 to January 2018 are retrospectively studied. A nomogram for disease-free survival (DFS) is constructed based on multivariate Cox regression analysis. The performance of the model is evaluated by using the area under the curve (AUC) of the receiver operating characteristic curve and Harrell concordance index (C-index). Then, the entire cohort is divided into different risk groups according to the nomogram cutoff value determined by X-tile analysis. The degree of comorbidities is assessed by the Charlson Comorbidity Index (CCI). Finally, survival rates are estimated and compared by the Kaplan-Meier method and the log-rank test. (3) Results: A nomogram for DFS is constructed with T/N classification, Epstein-Barr virus DNA and albumin. The nomogram shows well prognostic performance and significantly outperformed the tumor-node-metastasis staging system for estimating DFS (AUC, 0.710 vs. 0.607; C-index, 0.668 vs. 0.585; both p < 0.001). The high-risk group generated by nomogram has significantly poorer survival compared with the low-risk group (3-year DFS, 76.7% vs. 44.6%, p < 0.001). For high-risk patients with fewer comorbidities (CCI = 2), chemotherapy combined with radiotherapy is associated with significantly better survival (p < 0.05) than radiotherapy alone. (4) Conclusion: A prognostic nomogram for DFS is constructed with generating two risk groups. Combining risk stratification and the degree of comorbidities can guide risk-adapted treatment for elderly LA-NPC patients.

Individualized elective irradiation of the clinically node-negative neck in definitive radiotherapy for head and neck squamous cell carcinoma.

BACKGROUND: Oral cavity (OC), oropharyngeal (OP), hypopharyngeal (HP), and laryngeal (LA) squamous cell carcinoma (SCC) have a high incidence of regional lymph node metastasis (LNM). Elective irradiation for clinically node-negative neck is routinely administered to treat lymph nodes harboring occult metastasis. However, the optimal elective irradiation schemes are still inconclusive. In this study, we aimed to establish individualized elective irradiation schemes for the ipsilateral and contralateral node-negative neck of these four types of cancer. METHODS: From July 2005 to December 2018, 793 patients with OC-SCC, 464 with OP-SCC, 413 with HP-SCC, and 645 with LA-SCC were recruited retrospectively. Based on the actual incidence of LNM and the tumor characteristics, risk factors for contralateral LNM, as well as node level coverage schemes for elective irradiation, were determined using logistic regression analysis. Additionally, we developed a publicly available online tool to facilitate the widespread clinical use of these schemes. RESULTS: For the ipsilateral node-negative neck, elective irradiation at levels I-III for OC-SCC and levels II-IVa for OP-, HP- and LA-SCC are generally recommended. In addition, level VIIa should be included in patients with OP-SCC. Multivariate analyses revealed that posterior hypopharyngeal wall and post-cricoid region involvement were independently associated with level VIIa metastasis in HP-SCC (all P < 0.05). For the contralateral node-negative neck, multivariate analyses revealed that ipsilateral N2b2-N3, tumors with body midline involvement, and degree of tumor invasion were the independent factors for contralateral LNM (all P < 0.05). In patients who require contralateral neck irradiation, levels I-II are recommended for OC-SCC, and additional level III is recommended for patients with ipsilateral N3 disease. Levels II-III are recommended for OP-, HP-, and LA-SCC, and additional level IVa is recommended for patients with advanced T or ipsilateral N classifications. Furthermore, additional level VIIa is recommended only for OP-SCC with T4 and ipsilateral N3 disease. CONCLUSION: Based on our findings, we suggest that individualized and computer-aided elective irradiation schemes could reduce irradiation volumes in OC-, OP- and HP-SCC patients, as compared to current guidelines, and could thus positively impact the patients' quality of life after radiotherapy.

The E3 ubiquitin ligase gene SlRING1 is essential for plant tolerance to cadmium stress in Solanum lycopersicum.

The E3 ubiquitin ligases participate in the degradation of plant proteins and play a regulatory role in stress response. However, the role of tomato E3 ubiquitin ligase genes in plant response to heavy metal stress remains elusive. Here, we identified 17 tomato E3 ubiquitin ligase genes using blast analysis of highly expressed E3 ubiquitin ligase genes of Arabidopsis thaliana. Through organ expression analysis, three E3 ubiquitin ligase genes with higher expression levels in roots were further screened out, and they were named Sl1, SlRHE1, and SlRING1. Among these three genes, SlRING1 expression was the highest in response to cadmium (Cd) stress. Silencing SlRING1 significantly decreased chlorophyll content, Fv/Fm, photosynthetic rate, and biomass accumulation under Cd stress. The levels of H2O2, electrolyte leakage, and malondialdehyde significantly increased in SlRING1-silenced plants under Cd stress compared with that in non-silenced tomato plants. Cd stress-induced increases in the transcript levels of antioxidant and detoxification genes such as CAT, DHAR, MDHAR, GSH, and PCS were compromised by SlRING1 silencing. Moreover, Cd accumulation in shoots and roots significantly increased in SlRING1-silenced plants compared with non-silenced tomato plants. These findings suggest that SlRING1 plays a positive role in plant tolerance to Cd stress in tomato.

Clinical features and survival outcomes between ascending and descending types of nasopharyngeal carcinoma in the intensity-modulated radiotherapy era: A big-data intelligence platform-based analysis.

PURPOSE: To compare clinical features and survival outcomes in patients with ascending type (type A) and descending type (type D) nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era. MATERIALS AND METHODS: A total of 5194 patients with type A and type D NPC treated at Sun Yat-sen University Cancer Center were randomly selected. Tumors that were mainly advanced local disease (T3-4 stage) with early stage cervical lymph node involvement (N0-1 stage) were determined as type A, while tumors with advanced lymph node disease (N2-3 stage) but early stage local invasion (T1-2 stage) were classified as type D NPC. Kaplan-Meier's analysis was used to evaluate survival rates, and log-rank test survival curves were used for comparison. In the multivariate analysis Cox proportional hazard models were developed. RESULTS: There was a larger proportion of type A tumors (82%) than type D tumors (18%). Compared to patients with type A tumors, those with type D tumors had increased likelihood of distant metastasis, regional recurrence, disease recurrence, and death (P < 0.001 for all), however, not for local recurrence (P < 0.001). The HR (hazard ratio) for death following recurrence of disease for type D tumors were 1.6 compared to type A tumors. Multivariate analysis revealed that elevated EBV DNA, elevated lactate dehydrogenase, alcohol consumption, and no family history of cancer attributed to the development of type D tumors. Annual hazard rate in type A patients increased, peaking at 12-18 months after initial treatment and downward thereafter. Similar trend also occurred in type D during the first 5 years following treatment. Notably, a minor peak was also observed 7-8 years post treatment. CONCLUSIONS: In the IMRT era, recurrence patterns differed across tumor types. Type D NPC had a more aggressive clinical course and worse outcomes compared with type A NPC.

Evolution and Dosimetric Analysis of Magnetic Resonance Imaging-Detected Brain Stem Injury After Intensity Modulated Radiation Therapy in Nasopharyngeal Carcinoma.

PURPOSE: To evaluate the evolution of radiation-induced brain stem injury (BSI) in patients with nasopharyngeal carcinoma (NPC) treated with intensity modulated radiation therapy (IMRT) and to identify the critical dosimetric predictors of BSI. METHODS AND MATERIALS: A total of 6288 NPC patients treated with IMRT between 2009 and 2015 were retrospectively reviewed. Among these 6288 patients, 24 had radiation-induced BSI, which manifested as edematous lesions and contrast-enhanced lesions (CLs) on magnetic resonance imaging. Latency, symptoms, and evolution of BSI were assessed. Critical dosimetric predictors of BSI were identified using a penalized regression model with performance evaluated by receiver operating characteristic curve analysis. RESULTS: Median BSI latency was 14.5 months (range, 7.6-37.5 months), and 9 out of 24 patients (37.5%) were clinically symptomatic. Edematous lesions and CLs were both present in all patients. Necrosis was significantly more common in larger CLs (P = .007). After median follow-up of 12.5 months, 13 out of 24 patients (54.2%) had complete remission, and 5 out of 24 patients (20.8%) had partial remission. Remission was unaffected by whether or not symptomatic treatment was given. Maximum point dose (Dmax) was identified as the critical predictor of BSI (area under the receiver operating curve = 0.898), with the optimal cutoff equivalent dose in 2-Gy fractions (D2) being 67.4 Gy (sensitivity = 0.833, 20 out of 24; specificity = 0.835, 5234 out of 6264). Patients with Dmax ≥67.4 Gy (D2) were significantly more likely to develop BSI (odds ratio = 25.29; 95% CI, 8.63-74.14; P < .001) than those with Dmax <67.4 Gy (D2). CONCLUSIONS: In patients with NPC treated with IMRT, BSI generally tends to improve over time. Dmax = 67.4 Gy (D2) appears to be the dose constraint for brain stem, potentially providing clinicians with greater choice and flexibility when balancing the tumor target coverage and brain stem protection. Further studies are needed to validate our findings.

Identification and characterization of new Muscodor endophytes from gramineous plants in Xishuangbanna, China.

The endophytic fungi Muscodor spp. produce volatile organic compounds (VOCs) which can inhibit and even kill pathogenic fungi, bacteria, and nematodes. Nine endophytic fungal strains, isolated from the shoots of gramineous plants including Arthraxon hispidus, Eleusine indica, Oplismenus undulatifolius, and Oryza granulata, were identified as Muscodor through phylogenetic analysis of the internal transcribed spacer. Through an SPSS K-means cluster analysis, the nine Muscodor strains were divided into four groups based on the antifungal activities of the VOCs produced by these fungi determined by a two-section confrontation test. The first group contains the strains Y-L-54, W-S-41, Y-S-35, W-T-27, and Y-L-56, which showed the strongest activity. The second and third groups contain W-S-35 and Y-L-43, which showed stronger and moderate activity, respectively. The fourth group contains W-S-38 and N-L-7, which were the weakest in inhibiting the tested pathogens. Thirty-five compounds and the relative amounts of VOCs were determined by SPME-GC-MS and comparison with the NIST14 mass spectrometry database and Agilent MassHunter qualitative and quantitative analyses. These 35 compounds were classified into two different categories: (a) the product of fatty acid degradation, and (b) the intermediate and final metabolite of the metabolic pathway with the precursor of mevalonic acid. SPSS clustering analysis showed that the chemical components of VOCs might be correlated with their bioactivity rather than their phylogenetic assignment and some of the identified compounds might be responsible for antifungal activity. In conclusion, new Muscodor endophytes were recorded in tropical gramineous plants and a number of strains showed remarkable bioactive properties. Therefore, they have important potential applications in the fields of plant disease control.

Risk Assessment of Secondary Primary Malignancies in Nasopharyngeal Carcinoma: A Big-Data Intelligence Platform-Based Analysis of 6,377 Long-term Survivors from an Endemic Area Treated with Intensity-Modulated Radiation Therapy during 2003-2013.

PURPOSE: The incidence, risk factors and survival impact of secondary primary malignancies (SPMs) among survivors of nasopharyngeal carcinoma (NPC) treated with definitive intensity-modulated radiation therapy (IMRT) with or without chemotherapy are poorly characterized. METHODS AND MATERIALS: Consecutive patients (n=6,377) from the big-data intelligence platform at Sun Yat-sen University Cancer Center, China (in a high-incidence area) with newly diagnosed non-metastatic pathologically proven non-keratinizing undifferentiated NPC treated with IMRT±chemotherapy between January 2003 and June 2013 were retrospectively analyzed. Cumulative incidence of SPMs was calculated using the Kaplan-Meier method. Cox proportional hazards model was used to identify potential risk factors for SPMs and assess whether SPMs affect overall survival. RESULTS: Of the 6,377 patients, 189 (3.0%) suffered SPMs (median follow-up, 62 months). One-, 2-, 3-, 4-, and 5-cumulative risks of SPMs were 0.4%, 0.9%, 1.6%, 2.2%, and 2.6%, respectively. Latency from start of IMRT to SPMs diagnosis was 37 months (range, 6 to 102 months). In patients with SPMs, 14.3% suffered SPMs within 1 year post-IMRT: 1-3 years, 38.1%; 3-5 years, 33.9%; and >5 years, 13.7%. Lung cancer was the most common SPM (50/6,377, 0.78%). Multivariate analysis demonstrated sex (male, 64% increase), age (≥50 years, 68% increase), and smoking history (41% increase) were significant risk factors for SPMs, and SPMs were associated with poorer overall survival. CONCLUSION: This large cohort study confirms SPMs a dreadful complication for long-term survivors of NPC treated with IMRT. SPMs negatively impact overall survival in NPC. Close follow-up is recommended for older male survivors with a smoking history.

The detrimental effects of radiotherapy interruption on local control after concurrent chemoradiotherapy for advanced T-stage nasopharyngeal carcinoma: an observational, prospective analysis.

BACKGROUND: Previous studies have reported radiotherapy interruption (RTI) is associated with poor local control in two-dimensional radiotherapy (2DRT) era. However, it remains unclear whether RTI still affects local control for advanced T stage (T3-4) in the intensity-modulated radiation therapy (IMRT) era. We aim to evaluate whether RTI affects local control for T3-4 NPC treated with definitive IMRT. METHODS: In this observational prospective study, 447 T3-4 NPC patients treated with IMRT plus concurrent chemotherapy were included. All patients completed the planned radiotherapy course, and RTI was defined as the actual time taken to finish the prescribed course of radiotherapy minus the planned radiotherapy time. Receiver operating characteristic (ROC) curve was used for determined the cutoff point of RTI. The effects of RTI on local control were analyzed in multivariate analysis. RESULTS: At 5 years, the local relapse-free survival (LRFS) and overall survival (OS) rates were 93.7 and 85.7%, respectively. The cutoff RTI for LRFS was 5.5 days by ROC curve. Compared to patients with RTI >  5 days, patients with RTI ≤ 5 days had a significantly lower rate of LRFS (97% vs. 83%; P < 0.001). In multivariate analysis, RTI was a risk factor independently associated with LRFS (HR = 9.64, 95% CI, 4.10-22.65), but not for OS (HR = 1.09, 95% CI, 0.84-1.64). CONCLUSIONS: The current analysis demonstrates a significant correlation between prolonged RTI and local control in NPC, even when concurrent chemotherapy is used. We consider that attention to RTI seems to be warranted for patients with advanced T-stage NPC in the era of IMRT.

Melatonin alleviates low-sulfur stress by promoting sulfur homeostasis in tomato plants.

Despite involvement of melatonin (MT) in plant growth and stress tolerance, its role in sulfur (S) acquisition and assimilation remains unclear. Here we report that low-S conditions cause serious growth inhibition by reducing chlorophyll content, photosynthesis and biomass accumulation. S deficiency evoked oxidative stress leading to the cell structural alterations and DNA damage. In contrast, MT supplementation to the S-deprived plants resulted in a significant diminution in reactive oxygen species (ROS) accumulation, thereby mitigating S deficiency-induced damages to cellular macromolecules and ultrastructures. Moreover, MT promoted S uptake and assimilation by regulating the expression of genes encoding enzymes involved in S transport and metabolism. MT also protected cells from ROS-induced damage by regulating 2-cysteine peroxiredoxin and biosynthesis of S-compounds. These results provide strong evidence that MT can enhance plant tolerance to low-S-induced stress by improving S uptake, metabolism and redox homeostasis, and thus advocating beneficial effects of MT on increasing the sulfur utilization efficiency.

Delineation of Neck Clinical Target Volume Specific to Nasopharyngeal Carcinoma Based on Lymph Node Distribution and the International Consensus Guidelines.

PURPOSE: To establish the regional lymph node (LN) distribution probability map and draw the neck clinical target volume specific to nasopharyngeal carcinoma (NPC). METHODS AND MATERIALS: One thousand patients with pathologically proven NPC were enrolled from January 2010 to December 2011. The center point of the LNs with a minimal axial diameter of ≥4 mm was marked on a single treatment planning computed tomography scan. The neck LN levels I to X using the 2013 updated international consensus guidelines were also contoured. LN distribution probability maps and distribution curves were established. The relationships between the LN distribution and consensus guidelines were analyzed to propose modifications for clinical target volume boundaries specific to NPC. RESULTS: A total of 10,651 LNs from 959 patients were marked. Based on the distribution of LNs and consensus guidelines, most of the LN levels defined in the 2013 updated consensus guidelines were confirmed to be comprehensive and applicable for NPC. However, for level Vb, 13.3% of cases (11 of 83) had LNs beyond the posteromedial border. For level VIIa (retropharyngeal LN), 1.5% of cases (12 of 819) had LNs above the cranial boundary, and 5 cases had LNs that emerged in the medial group. Moreover, we confirmed that no LN had been detected in certain areas of levels Ib, II, IVa, and Vc. Accordingly, a new level VIIc was proposed to include the medial group of retropharyngeal LNs, moderately extended boundaries for levels Vb and VIIa were recommended, and reduced boundaries are possibly adaptable for levels Ib, II, IV, and Vc. CONCLUSIONS: Most LN levels in the 2013 updated consensus guidelines are comprehensive and applicable for NPC. We have proposed a new level VIIc to include a medial group of retropharyngeal LNs, recommended moderate extended boundaries for levels Vb and VIIa, and suggested that the boundaries for levels Ib, II, IV, and Vc might be reduced.

Melatonin Alleviates High Temperature-Induced Pollen Abortion in Solanum lycopersicum.

Melatonin is a pleiotropic signal molecule that plays critical roles in regulating plant growth and development, as well as providing physiological protections against various environmental stresses. Nonetheless, the mechanisms for melatonin-mediated pollen thermotolerance remain largely unknown. In this study, we report that irrigation treatment with melatonin (20 µM) effectively ameliorated high temperature-induced inactivation of pollen and inhibition of pollen germination in tomato (Solanum lycopersicum) plants. Melatonin alleviated reactive oxygen species production in tomato anthers under high temperature by the up-regulation of the transcription and activities of several antioxidant enzymes. Transmission electron micrograph results showed that high temperature-induced pollen abortion is associated with a premature degeneration of the tapetum cells and the formation of defective pollen grains with degenerated nuclei at the early uninuclear microspore stage, whilst melatonin protected degradation of organelles by enhancing the expression of heat shock protein genes to refold unfolded proteins and the expression of autophagy-related genes and formation of autophagosomes to degrade denatured proteins. These findings suggest a novel function of melatonin to protect pollen activity under high temperature and support the potential effects of melatonin on reproductive development of plants.

Optimal cumulative cisplatin dose in nasopharyngeal carcinoma patients receiving additional induction chemotherapy.

To clarify the optimal cumulative cisplatin dose (CCD) in locoregionally-advanced nasopharyngel carcinoma (NPC) patients receiving induction chemotherapy (IC) plus concurrent chemoradiotherapy (CCRT). Using the NPC-specific database from the established big-data intelligence platform at Sun Yat-Sen University Cancer Center, 583 non-disseminated, locoregionally-advanced NPC patients receiving IC plus CCRT were enrolled. Propensity score matching (PSM) analysis was conducted to control for confounding factors. The median CCD was 160 mg/m2 after IC (range, 40-300 mg/m2 ); only 74 patients (12.7%) achieved CCD >200 mg/m2 . Patients receiving >200 mg/m2 CCD did not show significantly improved 5-year overall survival (OS) (HR = 1.19; 95% confidence intervals [CI] 0.69-2.06, P = .53) and progression-free survival (PFS) (HR = 1.03; 95% CI: 0.63-1.68, P = .92) compared with patients receiving <200 mg/m2 CCD. Further investigations of the potential of median CCD (160 mg/m2 ) to yield survival benefits revealed that there were no significant differences in survival endpoints between patients receiving CCD >160 mg/m2 and CCD < 160 mg/m2 in both the original and PSM cohorts. In addition, subgroup analysis indicated a favorable PFS, but not OS, with higher cisplatin administration in patients with pretreatment Epstein-Barr virus deoxyribonucleic acid (EBV DNA) <1000 copies/mL (HR = 0.26, 95% CI: 0.07-0.93, P = .03) and receiving <3 IC cycles (HR = 0.59, 95% CI 0.33-1.07, P = .08). Our analysis of real world data provided references for the optimal CCD in locoregionally-advanced NPC receiving additional IC. The causal relationship between 200 mg/m2 CCD and improved survival was not defined; 160 mg/m2 CCD might be enough. However, for patients with EBV DNA <1000 copy/mL and receiving <3 IC cycles, a higher dose might be necessary.

Proposal of a Pretreatment Nomogram for Predicting Local Recurrence after Intensity-Modulated Radiation Therapy in T4 Nasopharyngeal Carcinoma: A Retrospective Review of 415 Chinese Patients.

PURPOSE: Local relapse-free survival (LRFS) differs widely among patients with T4 category nasopharyngeal carcinoma (NPC). We aimed to build a nomogram incorporating clinicopathological information to predict LRFS in T4 NPC after definitive intensity-modulated radiation therapy (IMRT). MATERIALS AND METHODS: Retrospective study of 415 Chinese patients with non-metastatic T4 NPC treated with definitive IMRT with or without chemotherapy at our cancer center between October 2009 and September 2013. The nomogram for LRFS at 3 and 5 years was generated based on multivariate Cox proportional hazards regression, and validated using bootstrap resampling, assessing discriminative performance using the concordance index (C-index) and determining calibration ability via calibration curves. RESULTS: Five-year LRFS was 88.8%. We identified and incorporated four independent prognostic factors for LRFS: ethmoid sinus invasion, primary gross tumor volume, age, and pretreatment body mass index. The C-index of the nomogram for local recurrence was 0.732 (95% confidence interval, 0.726 to 0.738), indicating excellent predictive accuracy. The calibration curve revealed excellent agreement between nomogram-predicted and observed LRFS probabilities. Risk subgroups based on total point score cutoff values enabled effective discrimination of LRFS. CONCLUSION: This pretreatment nomogram enables clinicians to accurately predict LRFS in T4 NPC after definitive IMRT, and could help to facilitate personalized patient counselling and treatment strategies.

Prognostic values of the integrated model incorporating the volume of metastatic regional cervical lymph node and pretreatment serum Epstein-Barr virus DNA copy number in predicting distant metastasis in patients with N1 nasopharyngeal carcinoma.

BACKGROUND: According to the 7th edition of the American Joint Committee on Cancer (AJCC) staging system, over 50% of patients with nasopharyngeal carcinoma (NPC) have N1 disease at initial diagnosis. However, patients with N1 NPC are relatively under-researched, and the metastasis risk of this group is not well-stratified. This study aimed to evaluate the prognostic values of gross tumor volume of metastatic regional lymph node (GTVnd) and pretreatment serum copy number of Epstein-Barr virus (EBV) DNA in predicting distant metastasis of patients with N1 NPC, and to develop an integrated prognostic model that incorporates GTVnd and EBV DNA copy number for this group of patients. METHODS: The medical records of 787 newly diagnosed patients with nonmetastatic, histologically proven N1 NPC who were treated at Sun Yat-sen University Cancer Center between November 2009 and February 2012 were analyzed. Computed tomography-derived GTVnd was measured using the summation-of-area technique. Blood samples were collected before treatment to quantify plasma EBV DNA. The receiver operating characteristic (ROC) curve analysis was used to evaluate the cut-off point for GTVnd, and the area under the ROC curve was used to assess the predicted validity of GTVnd. The survival rates were assessed by Kaplan-Meier analysis, and the survival curves were compared using a log-rank test. Multivariate analysis was conducted using the Cox proportional hazard regression model. RESULTS: The 5-year distant metastasis-free survival (DMFS) rates for patients with GTVnd > 18.9 vs. ≤ 18.9 mL were 82.2% vs. 93.2% (P < 0.001), and for patients with EBV DNA copy number > 4000 vs. ≤ 4000 copies/mL were 83.5% vs. 93.9% (P < 0.001). After adjusting for GTVnd, EBV DNA copy number, and T category in the Cox regression model, both GTVnd > 18.9 mL and EBV DNA copy number > 4000 copies/mL were significantly associated with poor prognosis (both P < 0.05). According to combination of GTVnd and EBV DNA copy number, all patients were divided into low-, moderate-, and high-risk groups, with the 5-year DMFS rates of 96.1, 87.4, and 73.8%, respectively (P < 0.001). Multivariate analysis confirmed the prognostic value of this model for distant metastatic risk stratification (hazard ratio [HR], 4.17; 95% confidence interval [CI] 2.34-7.59; P < 0.001). CONCLUSIONS: GTVnd and serum EBV DNA copy number are independent prognostic factors for predicting distant metastasis in NPC patients with N1 disease. The prognostic model incorporating GTVnd and EBV DNA copy number may improve metastatic risk stratification for this group of patients.

Patient- and treatment-related risk factors associated with neck muscle spasm in nasopharyngeal carcinoma patients after intensity-modulated radiotherapy.

BACKGROUND: To evaluate the incidence of neck muscle spasm in nasopharyngeal carcinoma (NPC) patients that received intensity-modulated radiotherapy (IMRT), and to analyse the patient- and treatment-related risk factors associated with neck muscle spasm. METHODS: A sample of 152 IMRT-treated, biopsy-proven, nondisseminated NPC patients were retrospectively analysed. All had documented IMRT treatment plans and had returned for follow-up review at 4 years post-radiotherapy. Spasm of the sternocleidomastoid (SCM) muscle was graded from 0 to 3 (absent to severe) and this grade served as the clinical endpoint. Risk factors were identified using logistic regression analysis. RESULTS: Within 4 years of radiotherapy, neck muscle spasm developed in 23.68% of the patients; Grades 0, 1, 2 and 3 were respectively assigned to 83.55, 7.57, 6.58 and 2.30% of assessed SCMs. Multivariate analysis indicated that gender, N stage, V60 (percentage of SCM volume that received >60 Gy) were independent prognostic variables, and that the optimal threshold for using V60 to predict neck muscle spasm was 61.92% (sensitivity = 0.900, specificity = 0.953). CONCLUSIONS: Gender, N stage and V60 were independent predictive factors for post-radiotherapy neck muscle spasm, and a V60 of ≤61.92% in the SCM was relatively safe.

Combined prognostic value of pretreatment anemia and cervical node necrosis in patients with nasopharyngeal carcinoma receiving intensity-modulated radiotherapy: A large-scale retrospective study.

This study investigated the combined prognostic value of pretreatment anemia and cervical node necrosis (CNN) in patients with nasopharyngeal carcinoma (NPC). Retrospective review of 1302 patients with newly diagnosed nonmetastatic NPC treated with intensity-modulated radiotherapy (IMRT) ± chemotherapy. Patients were classified into four groups according to anemia and CNN status. Survival was compared using the log-rank test. Independent prognostic factors were identified using the Cox proportional hazards model. The primary end-point was overall survival (OS); secondary end-points were disease-free survival (DFS), locoregional relapse-free survival (LRRFS), and distant metastasis-free survival (DMFS). Pretreatment anemia was an independent, adverse prognostic factor for DMFS; pretreatment CNN was an independent adverse prognostic factor for all end-points. Five-year survival for non-anemia and non-CNN, anemia, CNN, and anemia and CNN groups were: OS (93.1%, 87.2%, 82.9%, 76.3%, P < 0.001), DFS (87.0%, 84.0%, 73.9%, 64.6%, P < 0.001), DMFS (94.1%, 92.1%, 82.4%, 72.5%, P < 0.001), and LRRFS (92.8%, 92.4%, 88.7%, 84.0%, P = 0.012). The non-anemia and non-CNN group had best survival outcomes; anemia and CNN group, the poorest. Multivariate analysis demonstrated combined anemia and CNN was an independent prognostic factor for OS, DFS, DMFS, and LRRFS (P < 0.05). The combination of anemia and CNN is an independent adverse prognostic factor in patients with NPC treated using IMRT ± chemotherapy. Assessment of pretreatment anemia and CNN improved risk stratification, especially for patients with anemia and CNN who have poorest prognosis. This study may aid the design of individualized treatment plans to improve treatment outcomes.

Responses of Plant Proteins to Heavy Metal Stress-A Review.

Plants respond to environmental pollutants such as heavy metal(s) by triggering the expression of genes that encode proteins involved in stress response. Toxic metal ions profoundly affect the cellular protein homeostasis by interfering with the folding process and aggregation of nascent or non-native proteins leading to decreased cell viability. However, plants possess a range of ubiquitous cellular surveillance systems that enable them to efficiently detoxify heavy metals toward enhanced tolerance to metal stress. As proteins constitute the major workhorses of living cells, the chelation of metal ions in cytosol with phytochelatins and metallothioneins followed by compartmentalization of metals in the vacuoles as well as the repair of stress-damaged proteins or removal and degradation of proteins that fail to achieve their native conformations are critical for plant tolerance to heavy metal stress. In this review, we provide a broad overview of recent advances in cellular protein research with regards to heavy metal tolerance in plants. We also discuss how plants maintain functional and healthy proteomes for survival under such capricious surroundings.