Expression Interplay Between Cathepsin B and Its Natural Inhibitor Stefin A in Cancer and Embryonic Cell Lines

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Cathepsin B (CTSB) is a protease involved in cellular processes, but promotes cancer invasion and metastasis.
• Stefin A (STFA) is a natural inhibitor of CTSB.
• Dysregulation of CTSB and STFA is implicated in cancer progression.

Purpose of the Study:

• To investigate the regulatory relationship between CTSB and STFA in renal cancer cells.
• To elucidate the impact of CTSB expression and activity on STFA levels and localization.
• To compare the CTSB/STFA balance in cancer cells versus noncancerous embryonic cells.

Main Methods:

• Examined mRNA and protein expression of CTSB and STFA in Hek293T, 769p, and Du145 cell lines.
• Utilized CTSB gain-of-function, loss-of-function, and biochemical inhibition.
• Assessed reciprocal subcellular localization of CTSB and STFA.

Main Results:

• Cancer cells display impaired regulation of CTSB and STFA gene expression.
• Exogenous CTSB expression significantly alters STFA levels, indicating a feedback mechanism.
• The CTSB-STFA relationship is maintained at the protein level, suggesting translational regulation.

Conclusions:

• Aberrant CTSB expression influences its inhibitor STFA in cancer cells.
• Complex regulatory mechanisms exist at both transcriptional and translational levels.
• Understanding the CTSB/STFA balance offers insights into kidney cancer biology and progression.