The ABCB1 Knockout 143B Polyclonal Cells comprise a CRISPR/Cas9-mediated gene-disrupted population derived from the human 143B osteosarcoma cell line, designed to ablate P-glycoprotein (P-gp) function. This polyclonal knockout pool delivers a heterogeneous loss-of-function model that avoids clonal selection bias, enabling robust investigations of ATP-binding cassette (ABC) transporter biology and multidrug resistance (MDR). By disrupting the ABCB1 locus, the cells eliminate the primary efflux pump responsible for xenobiotic and cytotoxic drug clearance, making them an ideal tool for assessing transporter-dependent drug sensitivity, substrate specificity, and chemosensitizer efficacy in a bone-cancer context.
The parental 143B cell line, a highly tumorigenic and metastatic derivative of HOS human osteosarcoma, serves as a well-characterized model for bone metastasis and aggressive osteosarcoma progression. Its rapid growth and reproducible metastatic behavior in vivo provide a physiologically relevant platform for studying drug-transporter interactions within the bone tumor microenvironment. Combining the 143B background with ABCB1 disruption creates a powerful system to dissect how P-gp activity modulates chemotherapeutic response and to screen modulators that may reverse drug resistance in osteosarcoma.
ABCB1 encodes P-glycoprotein, an ATP-dependent efflux transporter that actively expels a broad spectrum of structurally diverse hydrophobic compounds, including anticancer agents such as doxorubicin and paclitaxel. Its expression is regulated upstream by transcription factors p53, NF-??B, YB-1, and nuclear receptors PXR (NR1I2) and CAR (NR1I3), and is further modulated by MAPK and PI3K/Akt signaling cascades. Active P-gp localizes to the plasma membrane, where it interacts with cholesterol, caveolin-1, ERM proteins (ezrin, radixin, moesin), annexin A2, and CD44, facilitating functional complex formation and efflux activity. Downstream, P-gp reduces intracellular drug accumulation, diminishing drug efficacy and conferring cellular protection against xenotoxins. The knockout model disrupts this axis, restoring intracellular retention of fluorescent substrates such as rhodamine 123 and calcein-AM, which can be quantified by flow cytometry or fluorescence-based assays.
In the 143B osteosarcoma context, ABCB1 knockout markedly sensitizes cells to conventional chemotherapeutics and clarifies the contribution of P-gp to broad-spectrum MDR. Without functional efflux capacity, drug accumulation increases, allowing direct correlation between transporter loss and drug-induced cytotoxicity. This system is particularly valuable for investigating resistance mechanisms in bone cancers, where high P-gp expression often limits therapeutic success, and for evaluating candidate chemosensitizers that may synergize with standard regimens.
Researchers can employ these polyclonal knockout cells for MDR pathway dissection, drug-transporter functional assays, and high-throughput chemosensitizer screening. Validation can be performed via Western blotting to confirm P-gp loss, RT-qPCR for ABCB1 mRNA quantification, and functional efflux assays using rhodamine 123 or calcein-AM. Parallel cytotoxicity assays with doxorubicin or paclitaxel, combined with ATPase activity measurements, enable comprehensive pharmacodynamic profiling. These applications support pharmacokinetic modeling, substrate specificity analysis, and the development of strategies to overcome MDR in osteosarcoma and beyond. For product inquiries or technical support, please contact Ascent Research.
