Inhibition of EZH2 alleviates SAHA-induced senescence-associated secretion phenotype in small cell lung cancer cells

Chemotherapy has been widely used in small cell lung cancer (SCLC) treatment in the past decades. However, SCLC is easy to recur after chemotherapy. The senescence of cancer cells during chemotherapy is one of the effective therapeutic strategies to inhibit the progression of cancer. Nevertheless, the senescence-associated secretion phenotype (SASP) promotes chronic inflammation of the cancer microenvironment and further accelerates the progression of tumors. Therefore, inducing the senescence of cancer cells and inhibiting the production of SASP factors during anticancer treatment have become effective therapeutic strategies to improve the anticancer effect of drugs. Here we reported that SCLC cells treated with an FDA-approved HDAC inhibitor SAHA underwent senescence and displayed remarkable SASP. In particular, SAHA promoted the formation of cytoplasmic chromatin fragments (CCFs) in SCLC cells. The increased CCFs in SAHA-treated SCLC cells were related to nuclear porin Tpr, which activated the cGAS-STING pathway, and promoted the secretion of SASP in cancer cells. Inhibition of EZH2 suppressed the increase of CCFs in SAHA-treated SCLC cells, weakened the production of SASP, and increased the antiproliferative effect of SAHA. Overall, our work affords new insight into the secretion of SASP in SCLC and establishes a foundation for constructing a new therapeutic strategy for SCLC patients.