In the described investigation, we unexpectedly found that the BT-549 breast cancer cell line with a high frequency of MN formation presented a low SASP phenotype but high autophagic activity, and subsequent experiments showed that its high DNA autophagy mediated by cGAS and cytosol-free DNA was closely related to MN formation and DNA damage, and inhibition of DNA autophagy could suppress its growth and survival. The gene discussed is CGAS; the disease is breast carcinoma.