GSE127264
Gene expression of clinical breast cancer cells cultured by sphere and adherent culture methods
Cancer stem-like cells (CSCs) are thought to be responsible for recurrence of tumors and poor prognosis because of their higher tumor initiating ability and drug resistance, though the mechanisms remain still unclear. Here, we show a critical role of mini-chromosome maintenance protein (MCM) 10, a component of DNA replication machinery, in enabling CSCs to deal with DNA replicative stress. Our transcriptomic analysis of patient-derived cultured breast cancer cells revealed that MCM10 is strongly upregulated in CSC-enriched spheroid cells, compared to cancer cells cultured in a regular condition. Elevated MCM10 expression was correlated with worse prognosis of patients with breast cancer. Depletion of MCM10 resulted in not only reduced cell proliferation and tumorigenesis, but also reduced tumor sphere forming efficiency, expression levels of stemness markers, and the tumor initiating ability. These results indicate that MCM10 is essential for maintenance of CSCs as well as for tumor cell proliferation. DNA fiber assay revealed that CSCs have a comparatively high level of DNA replicative stress. Overexpression of MCM10 helped cells to proliferate in a medium containing hydroxyurea (HU), a replicative stress-inducing chemotherapeutic agent. Conversely, MCM10 depletion made cells more fragile to replicative stress induced by HU or mitomycin C (MMC), another replicative stress inducer. Therefore, MCM10 plays critical roles for dealing with the enhanced replicative stress generated in CSCs for their survival, leading to maintenance of tumor initiating ability and drug resistance. We provide a preclinical rationale to target MCM10, the critical mediator for DNA replicative stress, for breast cancer that includes CSCs. Overall design: Conparison of expression between sphere and adherent cells derived from three breast tumors