
-   In human lung cancer tumors, cathepsins B and D mRNA levels did not correlate with any tumor characteristics. However, in most analyzed tumors, expression of cathepsin D mRNA was downregulated compared with adjacent normal tissue indicating cathepsin D mRNA may be a potential lung cancer marker [PMID: 20722505].
-   RNAseq on small cell lung cancer (SCLC) patients' tumor sample and normal lung tissue showed that an apoptosis-related, gene Cathepsin D (CTSD), was identified to be up-regulated in the low-risk group, and its higher expression correlated with better overall survival in SCLC. Functional enrichment analysis showed that the low-risk group was also enriched in the apoptosis pathway and high immune infiltration of T cells [PMID: 37189142].
-   In lungs of mice exposed to cigarette smoke or control air, there was a significant increase of matrix metalloproteinase (MMP)-12 and Cathepsin D mRNA, compared to air-exposed mice with Cathepsin D being predominantly expressed in macrophages [PMID: 16192742].
