Superoxide dismutase and cytochrome P450 isoenzymes might be associated with higher risk of renal cell carcinoma in male patients

Hint from an Enzymatic Reaction: Superoxide Dismutase Models Efficiently Suppress Colorectal Cancer Cell Proliferation

Superoxide dismutases (SODs) are essential antioxidant enzymes that prevent massive superoxide radical production and thus protect cells from damage induced by free radicals. However, this concept has rarely been applied to directly impede the function of driver oncogenes, thus far. Here, leveraging efforts from SOD model complexes, we report the novel finding of biomimetic copper complexes that efficiently scavenge intracellularly generated free radicals and, thereby, directly access the core consequence of colorectal cancer suppression. We conceived four structurally different SOD-mimicking copper complexes that showed distinct disproportionation reaction rates of intracellular superoxide radical anions. By replenishing SOD models, we observed a dramatic reduction of intracellular reactive oxygen species (ROS) and adenine 5'-triphosphate (ATP) concentrations that led to cell cycle arrest at the G2/M stage and induced apoptosis in vitro and in vivo. Our results showcase how nature-mimicking models can be designed and fine-tuned to serve as a viable chemotherapeutic strategy for cancer treatment.

Retinol Depletion in COVID-19

Background and aims

COVID-19 has been a devastating pandemic. There are indications that vitamin A is depleted during infections. Vitamin A is important in development and immune homeostasis. It has been used successfully in measles, RSV and AIDS infections. In this study, we aimed to measure the serum retinol levels in severe COVID-19 patients to assess the importance of vitamin A in the COVID-19 pathogenesis.

Methods

The serum retinol level was measured in two groups of patients: the COVID-19 group, which consisted of 27 severe COVID-19 patients hospitalized in the intensive care unit with respiratory failure, and the control group, which consisted of 23 patients without COVID-19 symptoms.

Results

The mean serum retinol levels were 0.37 mg/L in the COVID-19 group and 0.52 mg/L in the control group. The difference between the serum retinol levels in the two groups was statistically significant. There was no significant difference in retinol levels between different ages and genders within the COVID-19 group. Comorbidity did not affect serum retinol levels.

Conclusion

The serum retinol level was significantly lower in patients with severe COVID-19, and this difference was independent of age or underlying comorbidity. Our data show that retinol and retinoic acid signaling might be important in immunopathogenesis of COVID-19.

An aggregation-induced emission fluorescence probe for evaluating the effect of CYP450 changes under tumor chemotherapy

Cancer is a complex disease with very high incidence and mortality rates every year. However, cancer drug resistance greatly mitigates the cure rates of tumors, and cytochrome P450 (CYP450) plays an important role in the development of cisplatin resistance. We developed the aggregation-induced emission luminogen (AIEgen) TPE-CYP to monitor the changes in CYP450. The TPE-CYP fluorescent probe was successfully used to assess CYP450 levels in tumor cells and tumor tissue sections. This study presented that CYP450 level in HepG2/DDP cells (cisplatin-resistant cells) was higher than that in HepG2 cells, and the inhibition of CYP450 by 1-ABT effectively improved the tumor resistance. Thus, CYP450 plays a key role in the development of tumor resistance. The synergistic effect of 1-ABT and the chemotherapeutic agent cisplatin was superior to that of cisplatin alone in tumor-bearing mice. The TPE-CYP probe will provide an idea for the clinical implementation of individualized tumor treatment strategies, through the accurate monitoring of CYP450.

Volatilomics Reveals Potential Biomarkers for Identification of Renal Cell Carcinoma: An In Vitro Approach

The identification of noninvasive biomarkers able to detect renal cell carcinoma (RCC) at an early stage remains an unmet clinical need. The recognition that altered metabolism is a core hallmark of cancer boosted metabolomic studies focused in the search for cancer biomarkers. The present work aims to evaluate the performance of the volatile metabolites present in the extracellular medium to discriminate RCC cell lines with distinct histological subtypes (clear cell and papillary) and metastatic potential from non-tumorigenic renal cells. Hence, volatile organic compounds (VOCs) and volatile carbonyl compounds (VCCs) were extracted by headspace solid-phase microextraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). Multivariate and univariate analysis unveiled a panel of metabolites responsible for the separation between groups, mostly belonging to ketones, alcohols, alkanes and aldehydes classes. Some metabolites were found similarly altered for all RCC cell lines compared to non-tumorigenic cells, namely 2-ethylhexanol, tetradecane, formaldehyde, acetone (increased) and cyclohexanone and acetaldehyde (decreased). Furthermore, significantly altered levels of cyclohexanol, decanal, decane, dodecane and 4-methylbenzaldehyde were observed in all metastatic RCC cell lines when compared with the non-metastatic ones. Moreover, some alterations in the volatile composition were also observed between RCC histological subtypes. Overall, our results demonstrate the potential of volatile profiling for identification of noninvasive candidate biomarkers for early RCC diagnosis.

The SOD Mimic MnTnHex-2-PyP5+ Reduces the Viability and Migration of 786-O Human Renal Cancer Cells

Clear-cell renal carcinoma (ccRCC) is the most common type of renal cancer. The importance of oxidative stress in the context of this disease has been described, although there is only little information concerning the role of superoxide dismutase (SOD) enzymes. The importance of SOD in different pathological conditions promoted the development of SOD mimics (SODm). As such, manganese(III) porphyrins can mimic the natural SOD enzymes and scavenge different reactive oxygen species (ROS), thus modulating the cellular redox status. In this study, the exposure of 786-O human renal cancer cells to MnTnHex-2-PyP⁵⁺ (MnP), a very promising SODm, led to a concentration and time-dependent decrease in cell viability and in the cell proliferation indices, as well as to an increase in apoptosis. No relevant effects in terms of micronuclei formation were observed. Moreover, the exposure to MnP resulted in a concentration-dependent increase in intracellular ROS, presumably due to the generation of H₂O₂ by the inherent redox mechanisms of MnP, along with the limited ability of cancer cells to detoxify this species. Although the MnP treatment did not result in a reduction in the collective cell migration, a significant decrease in chemotactic migration was observed. Overall, these results suggest that MnP has a beneficial impact on reducing renal cancer cell viability and migration and warrant further studies regarding SODm-based therapeutic strategies against human renal cancer.

knnAUC: an open-source R package for detecting nonlinear dependence between one continuous variable and one binary variable

BACKGROUND

Testing the dependence of two variables is one of the fundamental tasks in statistics. In this work, we developed an open-source R package (knnAUC) for detecting nonlinear dependence between one continuous variable X and one binary dependent variables Y (0 or 1).

RESULTS

We addressed this problem by using knnAUC (k-nearest neighbors AUC test, the R package is available at https://sourceforge.net/projects/knnauc/ ). In the knnAUC software framework, we first resampled a dataset to get the training and testing dataset according to the sample ratio (from 0 to 1), and then constructed a k-nearest neighbors algorithm classifier to get the yhat estimator (the probability of y = 1) of testy (the true label of testing dataset). Finally, we calculated the AUC (area under the curve of receiver operating characteristic) estimator and tested whether the AUC estimator is greater than 0.5. To evaluate the advantages of knnAUC compared to seven other popular methods, we performed extensive simulations to explore the relationships between eight different methods and compared the false positive rates and statistical power using both simulated and real datasets (Chronic hepatitis B datasets and kidney cancer RNA-seq datasets).

CONCLUSIONS

We concluded that knnAUC is an efficient R package to test non-linear dependence between one continuous variable and one binary dependent variable especially in computational biology area.

Evaluation and prognostic significance of manganese superoxide dismutase in clear cell renal cell carcinoma

The antioxidant enzyme manganese superoxide dismutase (MnSOD) is up-regulated in renal cell carcinoma (RCC) and has been implicated in multiple stages of RCC tumorigenesis and progression. However, the prognostic significance of MnSOD in RCC has not been fully elucidated. This study aimed to investigate the expression profile of MnSOD in clear cell RCC (ccRCC) tissues and evaluate the clinical significance of this enzyme in ccRCC patients. MnSOD mRNA was assessed in 42 ccRCC and 33 normal kidney tissues using the Oncomine database, and its protein was detected in 145 ccRCCs and 3 normal tissues by immunohistochemistry staining. The Oncomine database confirmed higher MnSOD mRNA expression in ccRCC than in normal tissues, and immunohistochemistry analysis revealed that MnSOD protein expression was inversely associated with pathologic grade, clinical stage, tumor size, M status, and cancer-specific survival. In addition, univariate survival analysis demonstrated that high-grade, late-stage, large tumors, stage M₁, and low MnSOD expression were associated with a poorer prognosis for cancer-specific survival, and further multivariate analysis revealed that tumor grade, stage, M₁ stage, and MnSOD were identified as independent prognostic factors for cancer-specific survival in patients with ccRCC. Collectively, these findings imply that MnSOD is a promising prognostic marker in ccRCC and implies that oxidative stress might be involved in the tumorigenesis and progression of ccRCC.

Identification of metabolism-associated genes and pathways involved in different stages of clear cell renal cell carcinoma

The lack of early diagnostic markers and novel therapeutic targets for clear cell renal cell carcinoma (ccRCC) negatively affects patient prognosis. Cancer metabolism is an attractive area for the understanding of the molecular mechanism of carcinogenesis. The present study attempted to identify metabolic changes from the view of the expression of metabolism-associated genes between control samples and those of ccRCC at different disease stages. Data concerning ccRCC gene expression obtained by RNA-sequencing was obtained from The Cancer Genome Atlas and data on metabolism-associated genes were extracted using the Recon2 model. Following analysis of differential gene expression, multiple differentially expressed metabolic genes at each tumor-node-metastasis disease stage were identified, compared with control non-disease samples: Metabolic genes (305) were differentially expressed in stage I disease, 323 in stage II disease, 355 in stage III disease and 363 in stage IV disease. Following enrichment analysis for differential metabolic genes, 22 metabolic pathways were identified to be dysregulated in multiple stages of ccRCC. Abnormalities in hormone, vitamin, glucose and lipid metabolism were present in the early stages of the disease, with dysregulation to reactive oxygen species detoxification and amino acid metabolism pathways occurring with advanced disease stages, particularly to valine, leucine, and isoleucine metabolism, which was substantially dysregulated in stage IV disease. The xenobiotic metabolism pathway, associated with multiple cytochrome P450 family genes, was dysregulated in each stage of the disease. This pathway is worthy of substantial attention since it may aid understanding of drug resistance in ccRCC. The results of the present study offer information to aid further research into early diagnostic biomarkers and therapeutic targets of ccRCC.

LC-MS/MS Analysis Unravels Deep Oxidation of Manganese Superoxide Dismutase in Kidney Cancer

Manganese superoxide dismutase (MNSOD) is one of the major scavengers of reactive oxygen species (ROS) in mitochondria with pivotal regulatory role in ischemic disorders, inflammation and cancer. Here we report oxidative modification of MNSOD in human renal cell carcinoma (RCC) by the shotgun method using data-dependent liquid chromatography tandem mass spectrometry (LC-MS/MS). While 5816 and 5571 proteins were identified in cancer and adjacent tissues, respectively, 208 proteins were found to be up- or down-regulated (p < 0.05). Ontological category, interaction network and Western blotting suggested a close correlation between RCC-mediated proteins and oxidoreductases such as MNSOD. Markedly, oxidative modifications of MNSOD were identified at histidine (H⁵⁴ and H⁵⁵), tyrosine (Y⁵⁸), tryptophan (W¹⁴⁷, W¹⁴⁹, W²⁰⁵ and W²¹⁰) and asparagine (N²⁰⁶ and N²⁰⁹) residues additional to methionine. These oxidative insults were located at three hotspots near the hydrophobic pocket of the manganese binding site, of which the oxidation of Y⁵⁸, W¹⁴⁷ and W¹⁴⁹ was up-regulated around three folds and the oxidation of H⁵⁴ and H⁵⁵ was detected in the cancer tissues only (p < 0.05). When normalized to MNSOD expression levels, relative MNSOD enzymatic activity was decreased in cancer tissues, suggesting impairment of MNSOD enzymatic activity in kidney cancer due to modifications. Thus, LC-MS/MS analysis revealed multiple oxidative modifications of MNSOD at different amino acid residues that might mediate the regulation of the superoxide radicals, mitochondrial ROS scavenging and MNSOD activity in kidney cancer.