This study explores the specific role and underlying mechanisms of ALDH5A1 in the chemoresistance of esophageal squamous cell carcinoma (ESCC). The levels of cleaved caspase-3, 4-hydroxynonenal (4-HNE), intracellular Fe2+, and lipid reactive oxygen species (ROS) were evaluated via immunofluorescence. Cell viability and migration were quantified using cell counting kit-8 assays and wound healing assays, respectively. Flow cytometry was utilized to analyze cell apoptosis and ROS production. The concentrations of malondialdehyde (MDA) and reduced glutathione were determined by enzyme-linked immunosorbent assay. Proteome profiling was performed using data-independent acquisition. Additionally, a xenograft mouse model of ESCC was established to investigate the relationship between ALDH5A1 expression and the cisplatin (DDP)-resistance mechanism in vivo. ALDH5A1 is overexpressed in both ESCC patients and ESCC/DDP cells. Silencing of ALDH5A1 significantly enhances the inhibitory effects of DDP treatment on the viability and migration of KYSE30/DDP and KYSE150/DDP cells and promotes apoptosis. Furthermore, it intensifies DDP\'s suppressive effects on tumor volume and weight in nude mice. Gene ontology biological process analysis has shown that ferroptosis plays a crucial role in both KYSE30/DDP cells and KYSE30/DDP cells transfected with si-ALDH5A1. Our in vitro and in vivo experiments demonstrate that DDP treatment promotes the accumulation of ROS, lipid ROS, MDA, LPO, and intracellular Fe2+ content, increases the levels of proteins that promote ferroptosis (ACSL4 and FTH1), and decreases the expression of anti-ferroptosis proteins (SLC7A11, FTL, and GPX4). Silencing of ALDH5A1 further amplifies the regulatory effects of DDP both in vitro and in vivo. ALDH5A1 potentially acts as an oncogene in ESCC chemoresistance. Silencing of ALDH5A1 can reduce DDP resistance in ESCC through promoting ferroptosis signaling pathways. These findings suggest a promising strategy for the treatment of ESCC in clinical practice.

Thyroid cancer is the most common endocrine carcinoma, with papillary thyroid carcinoma (PTC) accounting for 80%-90% of thyroid cancers. Accumulating studies reported that mitochondria plays an important role in the regulation of cell proliferation. ALDH5A1, may function as an oncogene or tumour suppressor in various human cancers, and the role of ALDH5A1 in PTC is still unclear. The aim of this study was to investigate the clinical significance of ALDH5A1 expression and its functions in PTC. In this present study, we studied ALDH5A1 expression on primary papillary thyroid carcinoma (PTC) in The Cancer Genome Atlas (TCGA) database. Results showed that the levels of ALDH5A1 were found positively correlated with tumour stage, metastasis, lymph node stage, and higher levels of ALDH5A1 demonstrated poor disease-free survival (DFS). Immunohistochemistry (IHC) revealed that significantly higher expression of ALDH5A1 was found in PTC tissues. On the other hand, knockdown of ALDH5A1 significantly inhibited PTC cell proliferation, migration and invasion detection found the migration and invasion of cells also were hindered when ALDH5A1 level was reduced. The knockdown of ALDH5A1 inhibited the expression of Vimentin and promoted the expression of E-cadherin. In brief, knockdown of ALDH5A1may act as a novel molecular target for the prevention and treatment of PTC. SIGNIFICANCE OF THE STUDY: The present study focused on the role and the potential mechanism of ALDH5A1 in papillary thyroid carcinoma. We demonstrated that reduced expression of ALDH5A1 might inhibit the progression of TC by inhibiting cell proliferation, migration and invasion and reversing epithelial-mesenchymal transition (EMT). The findings ensured the interaction relation between ALDH5A1 and EMT in PTC, providing a novel biological marker for PTC and enriching the potential strategies for TC treatment.

Observed variations in drug responses among patients may result from differences in heritable genetic traits or from alterations in the epigenetic regulation of drug metabolizing enzymes and transporters (DMETs). MicroRNAs (miRNAs), a group of small non-coding RNAs, provide an epigenetic mechanism for fine-tuning the expression of targeted DMET genes by regulating the efficiency of protein translation and by decreasing mRNA stability via enhanced degradation. In the current study we systematically screened 374 important genes encoding DMETs for potential response elements to hsa-miR-29a-3p, a highly abundant miRNA in human liver. RNA electrophoresis mobility shift assays displayed direct interactions between hsa-miR-29a-3p and its cognate targets within the mRNA transcripts for the ABCC6, SLC22A7 and ALDH5A1 genes. The expression of luciferase reporter genes containing the 3\'-UTRs of SLC22A7 or ALDH5A1 and the expression of endogenous SLC22A7 and ALDH5A1 were each suppressed by transfection with hsa-miR-29a-3p mimics. Importantly, chemically-induced up-regulation of hsa-miR-29a-3p correlated inversely with the expression of SLC22A7 and ALDH5A1. However, our studies failed to detect suppressive effects of hsa-miR-29a-3p on ABCC6 expression, which might be explained by the notion that the interaction of hsa-miR-29a-3p and ABCC6 mRNA was unable to recruit ribonucleoproteins to form a RNA-induced silencing complex.