Interplay between oncogene-induced DNA damage response and heterochromatin in senescence and cancer

Area of Science:

• Cellular senescence research
• Cancer biology
• Epigenetics

Background:

• Cellular senescence is established by DNA damage response (DDR) and senescence-associated heterochromatic foci (SAHF).
• SAHF formation is critical in oncogene-induced senescence but its role in other senescence types is unclear.

Purpose of the Study:

• To investigate the role of SAHF in different senescence pathways.
• To explore the relationship between oncogene-induced heterochromatin, DDR, and cancer therapy.

Main Methods:

• Studied human fibroblasts resistant to p16(INK4a) induction.
• Utilized oncogene activation, replicative senescence, and various senescence-inducing stimuli.
• Investigated the roles of DNA replication, ATR, ATM, and p53.
• Analyzed heterochromatin markers in human cancers.
• Used pharmacological and genetic methods to perturb heterochromatin.
• Administered histone deacetylase inhibitors (HDACi) in vivo.

Main Results:

• SAHF preferentially form after oncogene activation, not during replicative senescence or other stimuli.
• Oncogene-induced SAHF formation requires DNA replication and ATR kinase.
• Inactivating ATM or p53 allows proliferation of oncogene-expressing cells with heterochromatin.
• Human cancers exhibit higher heterochromatin marker levels than normal tissues.
• Perturbing heterochromatin in oncogene-expressing cells enhances DDR and apoptosis.
• HDACi treatment in vivo leads to heterochromatin relaxation, increased DDR, apoptosis, and tumor regression.

Conclusions:

• Oncogenic stress-induced heterochromatin restrains the DNA damage response.
• Chromatin modification drugs may enhance cancer therapies by targeting heterochromatin and DDR.
• Tumor chromatin and DDR status are important considerations for therapeutic strategies.