The HMOX1 Knockout CAL-27 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population derived from the CAL-27 human tongue squamous cell carcinoma line. This product consists of a heterogeneous pool of cells with targeted disruptions in the HMOX1 gene, resulting in loss of heme oxygenase-1 (HO-1) function. The polyclonal format avoids clonal artifacts and maintains genetic diversity, ideal for pooled loss-of-function studies.
CAL-27 is a well-characterized human tongue squamous cell carcinoma line widely used as a model for oral squamous cell carcinoma (OSCC), the most common head and neck malignancy. These cells exhibit epithelial morphology, invasive capacity, and chemoresistance traits relevant to OSCC. In this context, HMOX1 is frequently overexpressed and contributes to tumor cell adaptation to oxidative stress and chemotherapy.
HMOX1 encodes heme oxygenase-1, which catalyzes heme degradation into biliverdin, carbon monoxide (CO), and iron. Biliverdin is reduced to bilirubin by BLVRA/B, providing potent antioxidant activity; CO signals through NF-??B inhibition and vasodilation; iron is sequestered by ferritin. HMOX1 expression is transcriptionally regulated via Nrf2?CKEAP1: under oxidative stress, Nrf2 dissociates from KEAP1, translocates to the nucleus, and binds ARE elements with small Maf proteins to induce target genes. Additional regulators include HIF-1??, AP-1, and the repressor Bach1, which competes for ARE binding. Interacting factors such as cytochrome P450 reductase donate electrons for catalysis.
In CAL-27 cells, HMOX1 knockout abolishes this cytoprotective response, blocking heme degradation and depleting biliverdin/CO production. This results in elevated reactive oxygen species (ROS), enhanced lipid peroxidation, and increased susceptibility to ferroptosis inducers like erastin. Loss of NF-??B inhibition by CO further promotes inflammation. Given the frequent upregulation of HO-1 in OSCC and its association with chemoresistance, this model enables dissection of heme metabolism contributions to drug resistance and redox homeostasis in a heterogeneous cell population.
Applications include RT-qPCR and western blotting for HMOX1 expression, heme oxygenase activity assays, ROS quantification with DCFDA, and lipid peroxidation detection. Cell viability assays under oxidative stress and ferroptosis induction, along with drug sensitivity testing using cisplatin or erastin, support chemoresistance studies. The model also facilitates interrogation of the Nrf2?CKEAP1 pathway in oral cancer. For further details and technical support, please contact Ascent Research.
