Low level of isocitrate dehydrogenase 1 predicts unfavorable postoperative outcomes in patients with clear cell renal cell carcinoma

Postoperative tumor treatment strategies: From basic research to clinical therapy

Despite progression in advanced treatments for malignant tumors, surgery remains the primary treatment intervention, which removes a large portion of firm tumor tissues; however, the postoperative phase poses a possible risk for provincial tumor recurrence and metastasis. Consequently, the prevention of tumor recurrence and metastasis has attracted research attention. In this review, we summarized the postoperative treatment strategies for various tumors from both basic research and clinical perspectives. We delineated the underlying factors contributing to the recurrence of malignant tumors with a substantial prevalence rate, related molecular mechanisms of tumor recurrence post‐surgery, and related means of monitoring recurrence and metastasis after surgery. Furthermore, we described relevant therapeutic approaches for postoperative tumor recurrence, including chemotherapy, radiation therapy, immunotherapy, targeted therapy, and photodynamic therapy. This review focused on the emerging technologies used for postoperative tumor treatment in recent years in terms of functional classification, including the prevention of postoperative tumor recurrence, functional reconstruction, and monitoring of recurrence. Finally, we discussed the future development and deficiencies of postoperative tumor therapy. To understand postoperative treatment strategies for tumors from clinical treatment and basic research and further guide the research directions for postoperative tumors.

Withaferin A Inhibits Liver Cancer Tumorigenesis by Suppressing Aerobic Glycolysis through the p53/IDH1/HIF-1α Signaling Axis

BACKGROUND

The energy supply of certain cancer cells depends on aerobic glycolysis rather than oxidative phosphorylation. Our previous studies have shown that withaferin A (WA), a lactone compound derived from Withania somnifera, suppresses skin carcinogenesis at least partially by stabilizing IDH1 and promoting oxidative phosphorylation. Here, we have extended our studies to evaluate the anti-tumor effect of WA in liver cancer.

METHODS

Differential expression of glycolysis-related genes between liver cancer tissues and normal tissues and prognosis were verified using an online database. Glycolysis-related protein expression was detected using western blot after overexpression and knockdown of IDH1 and mitochondrial membrane potential assay based on JC-1, and mitochondrial complex I activity was also detected. The inhibitory effect of WA on the biological functions of HepG2 cells was detected along with cell viability using MTT assay, scratch assay, clone formation assay, glucose consumption and lactate production assay. Western blot and qRT-PCR were used to detect the expression of proteins and genes related to IDH1, p53 and HIF1α signaling pathways.

RESULTS

We first identified that IDH1 expression was downregulated in human liver cancer cells compared to normal liver cells. Next, we found that treatment of HepG2 cells with WA resulted in significantly increased protein levels of IDH1, accompanied by decreased levels of several glycolytic enzymes. Furthermore, we found that WA stabilized IDH1 proteins by inhibiting the degradation by the proteasome. The tumor suppressor p53 was also upregulated by WA treatment, which played a critical role in the upregulation of IDH1 and downregulation of the glycolysis-related genes. Under hypoxic conditions, glycolysis-related genes were induced, which was suppressed by WA treatment, and IDH1 expression was still maintained at higher levels under hypoxia.

CONCLUSION

Taken together, our results indicated that WA suppresses liver cancer tumorigenesis by p53-mediated IDH1 upregulation, which promotes mitochondrial respiration, thereby inhibiting the HIF-1α pathway and blocking aerobic glycolysis.

Low expression of isocitrate dehydrogenase 1 (IDH1) R132H is associated with advanced pathological features in laryngeal squamous cell carcinoma

INTRODUCTION

Recent developments in genomic sequencing have led to the identification of somatic mutations in isocitrate dehydrogenase 1 (IDH1) in various malignancies. IDH1 R132H is the most common mutation of IDH1, which affects codon 132 and results in the conversion of amino acid residue arginine (R) to histidine (H). This study is designed to evaluate the association between the expression of IDH1 R132H and clinicopathological characteristics in laryngeal squamous cell carcinoma (LSCC).

METHODS

The expression pattern and clinical significance of IDH1 R132H were investigated in tissue microarrays (TMAs) of 50 LSCC tumors as well as adjacent normal tissues using immunohistochemistry. Then the exons of the 12 tumor samples with negative/weak positive staining were sequenced by applying polymerase chain reaction (PCR).

RESULTS

The results demonstrated that the cytoplasmic expression of IDH1 R132H was downregulated in tumor cells compared to adjacent normal tissues. A statistically significant association was found between a low level of cytoplasmic expression of IDH1 R132H protein and an increase in histological grade (p < 0.001), perineural invasion (p = 0.019), and lymph node involvement (p < 0.001). The exon4 sequencing results showed that only one sample was positive for IDH1 R132H mutation. IDH1 R132H expression was observed in 39 (78.0%) LSCC samples.

CONCLUSION

These findings indicate that low cytoplasmic expression of IDH1 R132H may have clinical significance in LSCC patients and is associated with more aggressive tumor behavior and progression of the disease, which can help improve potential treatment in patients with LSCC. Further investigations are needed to understand the biological function of IDH1 R132H and larger sample size to confirm our findings.

Involvement of Tricarboxylic Acid Cycle Metabolites in Kidney Diseases

Mitochondria are complex organelles that orchestrate several functions in the cell. The primary function recognized is energy production; however, other functions involve the communication with the rest of the cell through reactive oxygen species (ROS), calcium influx, mitochondrial DNA (mtDNA), adenosine triphosphate (ATP) levels, cytochrome c release, and also through tricarboxylic acid (TCA) metabolites. Kidney function highly depends on mitochondria; hence mitochondrial dysfunction is associated with kidney diseases. In addition to oxidative phosphorylation impairment, other mitochondrial abnormalities have been described in kidney diseases, such as induction of mitophagy, intrinsic pathway of apoptosis, and releasing molecules to communicate to the rest of the cell. The TCA cycle is a metabolic pathway whose primary function is to generate electrons to feed the electron transport system (ETS) to drives energy production. However, TCA cycle metabolites can also release from mitochondria or produced in the cytosol to exert different functions and modify cell behavior. Here we review the involvement of some of the functions of TCA metabolites in kidney diseases.

NADPH homeostasis in cancer: functions, mechanisms and therapeutic implications

Nicotinamide adenine dinucleotide phosphate (NADPH) is an essential electron donor in all organisms, and provides the reducing power for anabolic reactions and redox balance. NADPH homeostasis is regulated by varied signaling pathways and several metabolic enzymes that undergo adaptive alteration in cancer cells. The metabolic reprogramming of NADPH renders cancer cells both highly dependent on this metabolic network for antioxidant capacity and more susceptible to oxidative stress. Modulating the unique NADPH homeostasis of cancer cells might be an effective strategy to eliminate these cells. In this review, we summarize the current existing literatures on NADPH homeostasis, including its biological functions, regulatory mechanisms and the corresponding therapeutic interventions in human cancers, providing insights into therapeutic implications of targeting NADPH metabolism and the associated mechanism for cancer therapy.

Low Expression of Single-stranded DNA Binding Protein 2 (SSBP2) Predicts Unfavourable Postoperative Outcomes in Patients With Clear Cell Renal Cell Carcinoma

BACKGROUND

Single-stranded DNA binding protein 2 (SSBP2) is a subunit of a single-stranded DNA binding complex, which is involved in the maintenance of hematopoietic stem cells and stress responses. Numerous studies have suggested that SSBP2 functions as a tumor suppressor and is silenced through a pathway mediated by promoter hypermethylation. However, the role of SSBP2 in human renal cell carcinoma has not been reported, to date. Herein, we investigated the clinicopathological significance of SSBP2 expression in clear cell renal cell carcinoma (ccRCC).

MATERIALS AND METHODS

We constructed tissue micro arrays consisting of 173 ccRCC tissues, and SSBP2 expression was evaluated semi-quantitatively based on the staining intensity and the proportion of stained cells. Regarding statistical analysis, the tissues were divided into two groups according to SSBP2 expression, and correlation of SSBP2 expression with various clinicopathological characteristics and patient outcomes was evaluated.

RESULTS

Low SSBP2 expression was observed in 114 of 175 (65.9%) of ccRCC cases, and low SSBP2 expression was significantly correlated with larger tumor size (p=0.005, Chi-square test), higher WHO/ISUP histological grade (p<0.001, Chi-square test), tumor necrosis (p=0.008, Chi-square test), sarcomatoid change (p=0.021, Chi-square test), and higher pT AJCC stage (p=0.002, Chi-square test). Kaplan-Meier survival curves revealed that patients with low SSBP2 expression had worse recurrence-free survival (p=0.041, log-rank test).

CONCLUSION

ccRCC with low SSBP2 expression was associated with adverse clinicopathological characteristics and poor patient outcomes.

Urinary Metabolomics Validates Metabolic Differentiation Between Renal Cell Carcinoma Stages and Reveals a Unique Metabolic Profile for Oncocytomas

Renal cell carcinoma (RCC) is a heterogeneous malignancy which often develops and progresses asymptomatically. Benign oncocytomas are morphologically similar to malignant chromophobe RCC and distinguishing between these two forms on cross-sectional imaging remains a challenge. Therefore, RCC-specific biomarkers are urgently required for accurate and non-invasive, pre-surgical diagnosis of benign lesions. We have previously shown that dysregulation in glycolytic and tricarboxylic acid cycle intermediates can distinguish benign lesions from RCC in a stage-specific manner. In this study, preoperative fasting urine samples from patients with renal masses were assessed by ¹H nuclear magnetic resonance (NMR). Significant alterations in levels of tricarboxylic acid cycle intermediates, carnitines and its derivatives were detected in RCC relative to benign masses and in oncocytomas vs. chromophobe RCC. Orthogonal Partial Least Square Discriminant Analysis plots confirmed stage discrimination between benign vs. pT1 (R2 = 0.42, Q2 = 0.27) and benign vs. pT3 (R2 = 0.48, Q2 = 0.32) and showed separation for oncocytomas vs. chromophobe RCC (R2 = 0.81, Q2 = 0.57) and oncocytomas vs. clear cell RCC (R2 = 0.32, Q2 = 0.20). This study validates our previously described metabolic profile distinguishing benign tumors from RCC and presents a novel metabolic signature for oncocytomas which may be exploited for diagnosis before cross-sectional imaging.