Deficiency of SDHC promotes metastasis by reprogramming fatty acid metabolism in colorectal cancer.

BACKGROUND: Several studies have demonstrated a strong correlation between impaired Succinate dehydrogenase (SDH) function and the advancement of tumors. As a subunit of SDH, succinate dehydrogenase complex subunit C (SDHC) has been revealed to play tumor suppressive roles in several cancers, while its specific role in colorectal cancer (CRC) still needs further investigation. METHODS: Online database were utilized to investigate the expression of SDHC in colorectal cancer and to assess its correlation with patient prognosis. Cell metastasis was assessed using transwell and wound healing assays, while tumor metastasis was studied in a nude mice model in vivo. Drug screening and RNA sequencing were carried out to reveal the tumor suppressor mechanism of SDHC. Triglycerides, neutral lipids and fatty acid oxidation were measured using the Triglyceride Assay Kit, BODIPY 493/503 and Colorimetric Fatty Acid Oxidation Rate Assay Kit, respectively. The expression levels of enzymes involved in fatty acid metabolism and the PI3K/AKT signaling pathway were determined by quantitative real-time PCR and western blot. RESULTS: Downregulation of SDHC was found to be closely associated with a poor prognosis in CRC. SDHC knockdown promoted CRC metastasis both in vitro and in vivo. Through drug screening and Gene set enrichment analysis, it was discovered that SDHC downregulation was positively associated with the fatty acid metabolism pathways significantly. The effects of SDHC silencing on metastasis were reversed when fatty acid synthesis was blocked. Subsequent experiments revealed that SDHC silencing activated the PI3K/AKT signaling axis, leading to lipid accumulation by upregulating the expression of aldehyde dehydrogenase 3 family member A2 (ALDH3A2) and reduction of fatty acid oxidation rate by suppressing the expression of acyl-coenzyme A oxidase 1 (ACOX1) and carnitine palmitoyltransferase 1A (CPT1A). CONCLUSIONS: SDHC deficiency could potentially enhance CRC metastasis by modulating the PI3K/AKT pathways and reprogramming lipid metabolism.

[Correlation between serum iron level and overall survival of oral cancer].

OBJECTIVE: To explore the correlation between serum iron(Fe) and the overall survival of oral cancer. METHODS: Patients with oral cancer who met the inclusion criteria in the Department of Oral and Maxillofacial Surgery of the First Affiliated Hospital of Fujian Medical University from January 2010 to April 2017 were collected. The average age was(57.12±13.94) years old, including 489 males(65.46%), 258 females(34.54%) and 564 cases of squamous cell carcinoma(77.90%). Overall survival rates were calculated by Kaplan-Meier method. Survival difference was compared by log-rank test. Cox regression model was used to estimate the hazard ratio(HRs) and 95% confidence intervals(95%CIs). RESULTS: The distributions of serum iron level were non-normal distribution(P<0.001), and the serum iron level is expressed as 13.9(10.3, 17.8)µmol/L in M(P25, P75). According to X-tile, the optimal cut-off value of serum iron was 15.3 µmol/L, used as a criterion to group patients. The result showed that the mortality risk of patients with oral cancer in high serum iron level(Fe>15.3 µmol/L) was 0.72 times of patients in lower one(Fe≤15.3 µmol/L)(95%CI 0.52-0.99). Stratified analysis suggested that serum iron was a good predictor of patients with oral cancer aged 60 years(HR=0.62, 95%CI 0.39-0.99), male(HR=0.66, 95%CI 0.44-0.98), with TNM stage I-II(HR=0.42, 95%CI 0.20-0.88) and squamous cell of pathological type(HR=0.69, 95%CI 0.49-0.97). CONCLUSION: Serum iron is closely related to the overall survival of oral cancer, patients with high serum iron have a lower risk of death.