Reduced expression of DRAM2/TMEM77 in tumor cells interferes with cell death

Area of Science:

• Cell Biology
• Molecular Biology
• Oncology

Background:

• Autophagy's role in tumorigenesis is debated, with some evidence suggesting inhibition promotes tumor formation.
• Damage-regulated autophagy regulator (DRAM) is a known p53-mediated apoptosis effector.
• The existence of other DRAM-like molecules linking autophagy and apoptosis was investigated.

Purpose of the Study:

• To identify and characterize novel DRAM-homologous proteins.
• To investigate the role of DRAM2 in apoptosis and its potential involvement in ovarian tumorigenesis.

Main Methods:

• Cloning of a novel DRAM-homologous protein, DRAM2.
• Analysis of DRAM2 expression in ovarian tumors.
• Investigation of DRAM2 localization and co-localization with DRAM.
• Assessment of cell death induction upon DRAM or DRAM2 expression/co-expression.
• Evaluation of cell death changes upon silencing of endogenous DRAM2.

Main Results:

• A novel DRAM-homologous protein, DRAM2, was identified.
• DRAM2 expression was found to be down-regulated in ovarian tumors.
• DRAM2 localizes to the lysosome and co-localizes with DRAM.
• Individual expression of DRAM or DRAM2 did not induce cell death.
• Co-expression of DRAM2 with DRAM significantly induced cell death.
• Silencing of endogenous DRAM2 attenuated cell death, indicating its involvement in the process.

Conclusions:

• DRAM2 is a novel protein involved in cell death pathways.
• Reduced expression of DRAM2 may contribute to enhanced cell survival in tumor cells, potentially promoting ovarian tumorigenesis.