Gene signature predicting recurrence in oral squamous cell carcinoma is characterized by increased oxidative phosphorylation

Although numerous studies have used systemic approaches to identify prognostic predictors in oral squamous cell carcinoma (OSCC), the effectiveness of these approaches has not been assessed clinically. Further, the mechanism underlying malignant behaviors in OSCC is poorly characterized. This study aimed to develop and verify accurate prognostic predictors for OSCC patients and assess the associated biology. We identified an OSCC‐recurrence‐related gene signature (ORGS) using a Cox regression analysis. Functional enrichment analysis was used to identify enriched pathways and biological processes to reveal the underlying mechanism of OSCC malignant behavior. The ORGS successfully divided OSCC patients into low‐ and high‐risk groups with significantly different overall survivals. Pathway analysis revealed oxidative phosphorylation (OXPHOS) as a signaling pathway associated with the ORGS in OSCC. Interestingly, high OXPHOS status was strongly associated with poor overall survival in OSCC patients. Mediator complex subunit 30 (MED30) was a predicted upstream regulator of OXPHOS, and knockdown of MED30 reduced histone acetylation. We identified that the ORGS was strongly correlated with OXPHOS regulatory processes, suggesting OXPHOS as a key mechanism leading to poor prognosis in OSCC

KML001, a Telomere-Targeting Drug, Sensitizes Glioblastoma Cells to Temozolomide Chemotherapy and Radiotherapy through DNA Damage and Apoptosis

Standard treatment for glioblastoma comprises surgical resection, chemotherapy with temozolomide, and radiotherapy. Nevertheless, majority of glioblastoma patients have recurrence from resistance to the cytotoxic conventional therapies. We examined combinational effects of KML001, an arsenic compound targeting telomeres of chromosomes with temozolomide or irradiation, in glioblastoma cell lines and xenograft models, to overcome the therapeutic limitation of chemoradiation therapy for glioblastoma. Although KML001 alone showed little effects on in vitro survival of glioblastoma cells, cell death by in vitro temozolomide treatment or irradiation was synergistically potentiated by combination with KML001. Since phosphorylated γ-H2AX, cleaved casepase-3, and cleaved PARP were dramatically increased by KML001, the synergistic effects would be mediated by increased DNA damage and subsequent tumor cell apoptosis. Combinatorial effects of KML001 were observed not only in chemo- and radiosensitive glioblastoma cell line, U87MG, but also in the resistant cell line, U251MG. In the U87MG glioblastoma xenograft models, KML001 did not have systemic toxicity but showed synergistic therapeutic effects in combination with temozolomide or irradiation to reduce tumor volumes significantly. These data indicated that KML001 could be a candidate sensitizer to potentiate therapeutic effects of conventional cytotoxic treatment for glioblastoma

Development of a semi-open chamber system for the gas exchange measurement of whole-canopy under steady and unsteady states in cucumber seedlings

Abstract Background Large-scale data on the photosynthetic characteristics of whole crop canopy is crucial for improving yield. However, current data collection methods remain challenging, and the time constraints associated with photosynthetic data collection further complicate matters. Developing a practical yet easy-to-use tool for collecting whole-canopy data is essential to address these challenges. Furthermore, it is necessary to obtain instantaneous measurements of photosynthetic rate over a wide range of CO2 concentrations under an unsteady state to enable faster data collection and obtain reliable biochemical limits of carbon assimilation. This study developed a semi-open chamber system with steady and unsteady state measurement techniques to collect biochemical photosynthetic data from an entire cucumber canopy, emphasizing the correction procedures for CO2 concentration of unsteady state measurements applicable regardless of chamber scale. Results After constructing a semi-open chamber system, we described how to correct measurement errors according to chamber volume. In order to assess the accuracy of the newly developed system, an analysis was conducted to determine the overall measurement error resulting from variations in the reference, sample CO2 concentration, and leakage flow rate. The total measurement error was accurate to no more than 10%. Furthermore, the difference between the photosynthetic rate of the single leaf and that of the whole-canopy was not significant in Rubisco activity-limited carboxylation range. In addition, the Farquhar–von Caemmerer–Berry (FvCB) model parameters and the photosynthetic rate estimation values were compared to evaluate the steady- and unsteady state measurement methods between the cucumber seedlings' single-leaf and whole-canopy. The average root mean square error of the FvCB model in the steady (standard A-Ci response) and unsteady states (800 to 400 ramp) of the chambers was 1.4 and 2.3, respectively. Results show that the developed system is suitable for measuring the gas exchange rate of the cucumber canopy. Conclusions We demonstrate the correction method for measurement errors to enable the gas exchange rate of the whole-canopy even in an unsteady state. The correction method of the measurement system of the gas exchange rate for the whole- canopy can be applied regardless of the volume of the chamber, and it can be applied simply to other chamber systems. In addition, an unsteady state measurement method for fast data collection was also applicable. However, it was deemed necessary to identify a more optimal measurement range by conducting measurements across a broader range of values

CHIP Haploinsufficiency Exacerbates Hepatic Steatosis via Enhanced TXNIP Expression and Endoplasmic Reticulum Stress Responses

TXNIP is a critical regulator of glucose homeostasis, fatty acid synthesis, and cholesterol accumulation in the liver, and it has been reported that metabolic diseases, such as obesity, atherosclerosis, hyperlipidemia, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD), are associated with endoplasmic reticulum (ER) stress. Because CHIP, an E3 ligase, was known to be involved in regulating tissue injury and inflammation in liver, its role in regulating ER stress-induced NAFLD was investigated in two experimental NAFLD models, a tunicamycin (TM)-induced and other diet-induced NAFLD mice models. In the TM-induced NAFLD model, intraperitoneal injection of TM induced liver steatosis in both CHIP+/+ and CHIP+/− mice, but it was severely exacerbated in CHIP+/− mice compared to CHIP+/+ mice. Key regulators of ER stress and de novo lipogenesis were also enhanced in the livers of TM-inoculated CHIP+/− mice. Furthermore, in the diet-induced NAFLD models, CHIP+/− mice developed severely impaired glucose tolerance, insulin resistance and hepatic steatosis compared to CHIP+/+ mice. Interestingly, CHIP promoted ubiquitin-dependent degradation of TXNIP in vitro, and inhibition of TXNIP was further found to alleviate the inflammation and ER stress responses increased by CHIP inhibition. In addition, the expression of TXNIP was increased in mice deficient in CHIP in the TM- and diet-induced models. These findings suggest that CHIP modulates ER stress and inflammatory responses by inhibiting TXNIP, and that CHIP protects against TM- or HF–HS diet-induced NAFLD and serves as a potential therapeutic means for treating liver diseases

Evaluation of Growth and Photosynthetic Rate of Cucumber Seedlings Affected by Far-Red Light Using a Semi-Open Chamber and Imaging System

Far-red light was excluded in photosynthetic photon flux; however, recent studies have shown that it increases photosynthetic capacity. In addition, there were few studies on the whole canopy photosynthetic rate and continuous changes of morphology on cucumber seedlings affected by far-red light. This study evaluated the effect of conventional white LEDs adding far-red light on cucumber seedlings using a semi-open chamber system for the measurement of the whole canopy gas exchange rate, and the Raspberry Pi-based imaging system for the analysis of a continuous image. In the image, through the imaging system, it was confirmed that far-red light promoted the germination rate of cucumber seedlings and enhanced early growth. However, the dry weight of the shoot and root did not increase. The measured net apparent CO2 assimilation rate was improved by an increasing leaf area during the cultivation period. The conventional white LED light source with added far-red light increased the photosynthetic rate of cucumber seedlings’ whole canopy. However, at the early seedling stage, plant height and leaf area of the whole canopy was increased by far-red light, and it was revealed that the image data saturated faster. It was considered that the photosynthetic efficiency decreased due to a shading effect of the limited planting density of the cell tray. The results found that using appropriate far-red light, considering planting density, could increase the photosynthetic rate of the whole canopy of crops, thereby promoting crop growth, but it was judged that the use of far-red light in the early growth stage of cucumber seedlings should be considered carefully

NADH elevation during chronic hypoxia leads to VHL-mediated HIF-1α degradation via SIRT1 inhibition

Abstract Background Under conditions of hypoxia, cancer cells with hypoxia inducible factor-1α (HIF-1α) from heterogeneous tumor cells show greater aggression and progression in an effort to compensate for harsh environmental conditions. Extensive study on the stability of HIF-1α under conditions of acute hypoxia in cancer progression has been conducted, however, understanding of its involvement during the chronic phase is limited. Methods In this study, we investigated the effect of SIRT1 on HIF1 stability in a typical chronic hypoxic conditon that maintains cells for 24 h under hypoxia using Western blotting, co-IP, measurement of intracellular NAD + and NADH levels, semi-quantitative RT-PCR analysis, invasion assay, gene knockdown. Results Here we demonstrated that the high concentration of pyruvate in the medium, which can be easily overlooked, has an effect on the stability of HIF-1α. We also demonstrated that NADH functions as a signal for conveyance of HIF-1α degradation via the SIRT1 and VHL signaling pathway under conditions of chronic hypoxia, which in turn leads to attenuation of hypoxically strengthened invasion and angiogenic activities. A steep increase in the level of NADH occurs during chronic hypoxia, leading to upregulation of acetylation and degradation of HIF-1α via inactivation of SIRT1. Of particular interest, p300-mediated acetylation at lysine 709 of HIF-1α is recogonized by VHL, which leads to degradation of HIF-1α via ubiquitin/proteasome machinary under conditions of chronic hypoxia. In addition, we demonstrated that NADH-elevation-induced acetylation and subsequent degradation of HIF-1α was independent of proline hydroxylation. Conclusions Our findings suggest a critical role of SIRT1 as a metabolic sensor in coordination of hypoxic status via regulation of HIF-1α stability. These results also demonstrate the involvement of VHL in degradation of HIF-1α through recognition of PHD-mediated hydroxylation in normoxia and p300-mediated HIF-1α acetylation in hypoxia

SIRT1 interacts with and protects glyceraldehyde-3-phosphate dehydrogenase (GAPDH) from nuclear translocation: Implications for cell survival after irradiation

Upon apoptotic stimulation, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a cytosolic enzyme normally active in glycolysis, translocates into the nucleus and activates an apoptotic cascade therein. In the present work, we show that SIRT1 prevents nuclear translocation of GAPDH via interaction with GAPDH. SIRT1 depletion triggered nuclear translocation of cytosolic GAPDH even in the absence of apoptotic stress. Such translocation was not, however, observed when SIRT1 enzymatic activity was inhibited, indicating that SIRT1 protein per se, rather than the deacetylase activity of the protein, is required to inhibit GAPDH translocation. Upon irradiation, SIRT1 prevented irradiation-induced nuclear translocation of GAPDH, accompanied by interaction of SIRT1 and GAPDH. Thus, SIRT1 functions to retain GAPDH in the cytosol, protecting the enzyme from nuclear translocation via interaction with these two proteins. This serves as a mechanism whereby SIRT1 regulates cell survival upon induction of apoptotic stress by means that include irradiation. (c) 2012 Elsevier Inc. All rights reserved

Mitomycin C and doxorubicin elicit conflicting signals by causing accumulation of cyclin E prior to p21(WAF1/CIP1) elevation in human hepatocellular carcinoma cells

Proteins involved in the G, phase of the cell cycle are aberrantly expressed, sometimes in mutated forms, in human cancers including human hepatocellular carcinoma. Upon attack by a DNA-damaging anticancer drug, a cell arrests at the G, phase; this is a safety feature prohibiting entry of DNA-damaged cells into S-phase. p21(WAF1/CIP1) prevents damaged cells from progressing to the next cell cycle. Here, we show that, in response to mitomycin C and doxorubicin, human hepatocellular carcinoma cells generate conflicting signals, mediated by cycl in E and p21(WAF1/CIP1), which respectively accelerates and represses cell cycle transition. Exposure to these anticancer drugs led to rapid accumulation of cyclin E in both p53-proficient HepG2 and p53-deficient Hep3B cells. Such anticancer drug-induced cyclin E accumulation influenced the G(1)-S-phase transition, but not DNA fragmentation-mediated death. In p53-proficient HepG2 cells, accumulation of cyclin E was followed by an increase in the level of p53-dependent p21(WAF1/CIP1), thereby inhibiting further the G(1)-S-phase transition. Sublethal drug concentrations also induced rapid accumulation of cyclin E. but p21(WAF1/CIP1) accumulation was delayed, further facilitating the CO-phase transition. Eventually, most cells arrested in G(2)/M. Thus, mitomycin C- or doxorubicin-induced conflicting signals, mediated by cyclin E and p21(WAF1/CIP1), are in play in human hepatocellular carcinoma cells. Damaged G, cells either immediately enter S-phase, or do not do so at all, depending on the extent of DNA damage

Clonal cell populations unresponsive to radiosensitization induced by telomerase inhibition

A combination of a radiotherapeutic regimen with telomerase inhibition is valuable when tumor cells are to be sensitized to radiation. Here, we describe cell clones unresponsive to radiosensitization after telomere shortening. After extensive division of individual transformed clones of mTERC(-/-) cells, about 22% of clones were unresponsive to radiosensitization even though telomerase action was inhibited. The telomere lengths of unsensitized mTERC(-/-) clones were reduced, as were those of most sensitized clones. However, the unsensitized clones did not exhibit chromosomal end-to-end fusion to the extent noted in all sensitized clones. Thus, a defense mechanism preventing telomere erosion is operative even when telomeres become shorter under conditions of telomerase deficiency, and results in unresponsiveness to the radiosensitization generally mediated by telomere shortening. (C) 2010 Elsevier Inc. All rights reserved