Gene expression data in MDA231-LM2 breast cancer cells cultured as oncospheres

In advanced malignancies, cancer cells have acquired capabilities to resist a variety of stress-inducing insults. We show that c-Jun N-terminal kinase (JNK) stress signaling is highly active in cancer cells from patients with late stage breast cancer and promotes tumor growth and metastasis in mouse models. Transcriptomic analysis revealed that JNK activity induces genes associated with extracellular matrix (ECM), wound healing and mammary stem cells. The ECM proteins and niche components osteopontin (SPP1) and tenascin C (TNC) are induced by JNK signaling and promote metastatic colonization of the lungs. Notably, treatment with chemotherapeutic drugs induces JNK activity in breast cancer cells, reinforcing the production of SPP1 and TNC. Inhibition of JNK or reduction of SPP1 or TNC expression sensitizes primary tumors and metastases in mice to chemotherapy. We used Affymetrix microarrays to investigate gene expression changes upon culturing metastatic breast cancer cells as oncospheres, in ultra-low adhesive plates in the absence of serum, in contrast to regular monolayer culture conditions. Gene expression in MDA231-LM2 cells grown as oncospheres (seeded on ultra-low adhesive plates under serum-free conditions) was compared to gene expression in the same cells grown as a monolayer. Layer cultures were grown for 48 hours and oncospheres were collected 4 days after seeding.