The prevalence of secondary hyperparathyroidism (SHPT) in advanced chronic kidney disease (CKD) exceeds 80%. Our previous study indicated that photodynamic therapy (PDT) has potential for treating SHPT. Long noncoding RNA (lncRNA) is involved in various oxidative stress and apoptotic processes, but the molecular mechanism remains unreported. In this study, we found that PDT induced apoptosis in SHPT through reactive oxygen species (ROS) accumulation. The expression of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and heme oxygenase 1 (HO-1) within SHPT was upregulated after PDT. Inhibition of MALAT1 increased PDT-induced ROS, which promoted the apoptosis. Pearson correlation analysis confirmed that there was a positive correlation between MALAT1 and HO-1, and MALAT1 inhibition down-regulated HO-1, whereas concomitant overexpression of HO-1 was able to eliminate the PDT-induced ROS and inhibit apoptosis. The direct binding of MALAT1 to Kelch-like ECH-associated protein 1 (Keap1) protein was confirmed by high-throughput sequencing, RNA pulldown, silver staining and western blotting assays. Si-Keap1 was able to rescue the down-regulation of HO-1 caused by MALAT1 inhibition, restoring the elimination of ROS by HO-1 and attenuating the effect of PDT. In addition, PDT effectively reduced parathyroid hormone (PTH) secretion in SHPT rats, and this effect was further enhanced in combination with MALAT1 inhibitors. Overall, MALAT1 activates downstream HO-1 expression by binding to Keap1, thereby reducing ROS and inhibiting apoptosis, which in turn mediates PDT resistance in SHPT. Inhibition of MALAT1 significantly enhanced the efficacy of PDT, suggesting a potential therapeutic target for improving PDT for SHPT outcomes.
Background The aim of this study was to identify changes in gene expression before and after 5-aminolevulinic acid-mediated photodynamic therapy (5-ALA-PDT) and to investigate the potential mechanism of 5-ALA-PDT based on ribonucleic acid sequencing (RNA-Seq) analysis. Methods Secondary hyperparathyroidism (SHPT) primary cells were isolated from surgically excised specimens and exposed to laser light. The transcription profiles of SHPT primary cells were identified through RNA-Seq. Differentially expressed genes (DEGs) were identified. Enrichment of functions and signaling pathway analysis were performed based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Quantitative real-time polymerase chain reaction (RT-qPCR) and western blot analysis were used to validate genes based on RNA-Seq results. Results In total, 1320 DEGs were identified, of which 1019 genes were upregulated and 301 genes were downregulated. GO and KEGG pathway analyses identified significantly enriched pathways in DEGs, including TGF beta in extracellular matrix (ECM), negative regulation of triglyceride biosynthetic process, protein heterodimerization activity, systemic lupus erythematosus, ECM–receptor interaction, focal adhesion and protein digestion and absorption. Protein–protein interaction (PPI) network analyses identified potential heat shock protein (HSP) interactions among the DEGs. Eight HSP genes were also identified that were most likely involved in 5-ALA-PDT, which were further validated by RT-qPCR and western blotting. Conclusions The findings of this descriptive study reveal changes in the transcriptome profile during 5-ALA-PDT, suggesting that gene expression and mutation, signaling pathways, and the molecular network are altered in SHPT primary cells. The above findings provide new insight for further studies on the mechanisms underlying 5-ALA-PDT in SHPT. Graphical abstract
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