Notch1 signaling modulates hypoxia-induced multidrug resistance in human laryngeal cancer cells

Laryngeal carcinoma is one of the common malignant tumors of the head and neck. Multidrug resistance (MDR) remains a critical problem in the chemotherapy of patients with laryngeal cancer. This study aims to clarify the role and mechanisms of Notch1 signaling in MDR induced by hypoxia in laryngeal cancer cells. Laryngeal carcinoma cells were cultured under normoxia or hypoxia. Notch1 expression was inhibited by small interfering RNA (siRNA). The mRNA expression of Notch1, Hes1, Hey1, MDR1 and survivin was analyzed by real-time PCR. The protein expression of Notch1, the Notch1 intracellular domain (N1ICD), MDR1/P-gp and survivin was analyzed by Western blotting. Current research has shown that hypoxia can upregulate Notch1 expression and Notch1 signaling activity. Furthermore, suppression of Notch1 expression effectively downregulated Notch1 signaling activity and the expression of the MDR and survivin genes in laryngeal cancer cells under hypoxic conditions (P < 0.05). The Cell Counting Kit-8 (CCK-8) assay results confirmed that the sensitivity of hypoxic laryngeal cancer cells to a variety of drugs could be upregulated by suppressing Notch1 expression (P < 0.05). Additionally, flow cytometry (FCM) showed that suppression of Notch1 expression significantly increased drug-induced apoptosis and intracellular rhodamine 123 (Rh123) accumulation in hypoxic laryngeal carcinoma cells (P < 0.05). Notch1 signalling could be regarded as a pivotal regulator of hypoxia-induced MDR in laryngeal cancer cells through the regulation of survivin-mediated apoptosis resistance and MDR1/P-gp-mediated drug transport.