Since therapy‐induced senescence (TIS) can either support or inhibit cancer progression, identifying which types of chemotherapeutic agents can produce the strongest anti‐tumor TIS is an important issue. Here, cyclin‐dependent kinase4/6 inhibitors (CDK4/6i)‐induced senescence was compared to the TIS induced by conventional DNA‐damaging agents. Despite both types of agents eliciting a similar degree of senescence, we observed increased expression of the senescence‐associated secretory phenotype (SASP) and ligands related to pro‐tumor immunity (IL6, CXCL8, TGFβ, CD274, and CEACAM1) and angiogenesis (VEGFA) mainly in TIS induced by DNA‐damaging agents rather than by CDK4/6i. Additionally, although all agents increased the expression of anti‐tumor immunomodulatory proteins related to antigen presentation (MHC‐I, B2M) and T cell chemokines (CXCL9, 10, 11), CDK4/6i‐induced senescent cells still maintained this expression at a similar or even higher intensity than cells treated with DNA‐damaging agents, despite the absence of nuclear factor‐kappa‐B (NF‐κB) and p53 activation. These data suggest that in contrast with DNA‐damaging agents, which augment the pro‐tumorigenic microenvironment via pro‐inflammatory SASP, CDK4/6i can generate TIS only with antitumor immunomodulatory proteins.

Choi YW, et al. J Korean Med Sci. 2014 Nov;29(11):1493-1500. http://dx.doi.org/10.3346/jkms.2014.29.11.1493

Accumulating evidence indicates a link between diabetes and cancer. Selective estrogen receptor modulators (SERMs) may increase diabetes risk via antiestrogen effects. This study investigated incident diabetes risk of SERM treatment and its effects on metastatic cancer and death prevention in breast cancer survivors. This retrospective cohort study included female patients with early-stage breast cancer, treated with or without SERMs, between 2008 and 2020 in a tertiary care hospital in Korea. Four propensity score-matched comparison pairs were designed: SERM use versus non-use, long-term use (≥1500 days) versus non-use, tamoxifen use versus non-use, and toremifene use versus non-use; then, logistic regression analysis was performed for risk analysis. SERMs in general were not associated with an elevated risk of diabetes; however, when used for ≥1500 days, SERMs—especially toremifene—substantially increased diabetes risk in breast cancer patients (OR 1.63, p = 0.048). Meanwhile, long-term SERM treatment was effective at preventing metastatic cancer (OR 0.20, p < 0.001) and death (OR 0.13, p < 0.001). SERM treatment, albeit generally safe and effective, may increase diabetes risk with its long-term use in women with breast cancer. Further studies are required to verify the association between toremifene treatment and incident diabetes.

Choi YW, et al. J Korean Med Sci. 2015 Oct;30(10):1416-1422. http://dx.doi.org/10.3346/jkms.2015.30.10.1416

The transcriptional regulation of p53-dependent genes in response to DNA damage is critical for effective DNA repair and cell survival. We previously established that RSF1 (remodeling and spacing factor 1) is necessary for p53-dependent gene transcription in response to DNA strand breaks. Here, we further elucidate that the role of RSF1 in p53 regulation by demonstrating that its depletion results in a reduction in the acetylated-Lys(K)382 level of p53, which governs its transcriptional activity. RSF1 was co-precipitated with p300 acetyltransferase upon etoposide treatment. Chromatin immunoprecipitation assays on the upstream region of CDKN1A gene revealed reduced p300 and TBP accumulation, which were accompanied with low H3H27ac and H3K4me1 levels in RSF1 knockout cells. Moreover, RSF1 depletion led to a reduced accumulation of SSRP1 and SPT16, subunits of FACT complex at the promoter of CDKN1A gene. These findings suggest that RSF1 promotes p53-dependent p21 gene transcription by facilitating the accumulation of p300 acetyltransferase at the enhancer and FACT at the promoter region of CDKN1A gene, respectively.