cCMP causes caspase-dependent apoptosis in mouse lymphoma cell lines

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Cyclic CMP (cCMP) is a cyclic pyrimidine nucleotide known to activate cyclic AMP-dependent protein kinase (PKA) and cyclic GMP-dependent protein kinase (PKG).
• In S49 lymphoma cells, cyclic AMP (cAMP) induces apoptosis through PKA activation.
• The specific role of cCMP in apoptosis, particularly its signaling pathways and target proteins, remains incompletely understood.

Purpose of the Study:

• To investigate the effect of cCMP on apoptosis in S49 mouse lymphoma cells, including PKA-deficient variants.
• To elucidate the signaling pathways and molecular mechanisms by which cCMP induces apoptosis.
• To determine whether cCMP-mediated apoptosis is dependent on PKA, PKG, or other known cyclic nucleotide signaling pathways.

Main Methods:

• Treatment of S49 wild-type and PKA-deficient S49kin(-) lymphoma cells with the cell-permeable cCMP analog, cCMP-AM.
• Assessment of apoptosis induction, caspase activation, and mitochondrial cytochrome c release.
• Analysis of the involvement of intrinsic and extrinsic apoptotic pathways, ER stress, autophagy, and gene expression changes (Gadd45α, cFos, Nr4A1).

Main Results:

• cCMP-AM induced apoptosis in S49 cells independently of PKA and PKG.
• cCMP-induced apoptosis was caspase-dependent, proceeded via the intrinsic pathway, involved cytochrome c release and ER stress activation, but not the extrinsic pathway.
• cCMP-AM altered the expression of apoptotic-related genes (Gadd45α) and immediate early response genes (cFos, Nr4A1) in S49 wild-type cells.

Conclusions:

• cCMP induces apoptosis in S49 lymphoma cells through a caspase-dependent intrinsic pathway, independent of PKA and PKG.
• The mechanism involves mitochondrial dysfunction and ER stress activation, but not the extrinsic apoptotic pathway or autophagy.
• cCMP represents a novel inducer of apoptosis in these cells, acting independently of previously identified cCMP target proteins.