The GNPTG Knockout NCI-H1975 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal cell population featuring targeted disruption of the GNPTG gene in the human NCI-H1975 cell line. This knockout model provides a genetically heterogeneous pool of cells with loss-of-function mutations in GNPTG, enabling functional studies of the gamma subunit of GlcNAc-1-phosphotransferase without clonal biases. The polyclonal format retains genetic diversity, making it suitable for population-level analyses of lysosomal enzyme trafficking and metabolic pathways.
NCI-H1975 is a well-characterized human non-small cell lung cancer (NSCLC) line derived from the lung adenocarcinoma of a non-smoker female. This adherent epithelial cell line harbors oncogenic mutations, including EGFR L858R and T790M, and is commonly employed in lung cancer research. Its lung adenocarcinoma origin and genetic background provide a relevant epithelial context for investigating the interplay between oncogenic signaling and lysosomal homeostasis.
GNPTG encodes the gamma subunit of N-acetylglucosamine-1-phosphotransferase, a heterohexameric enzyme that catalyzes the initial step in mannose-6-phosphate (M6P) recognition marker synthesis. Together with the alpha and beta subunits encoded by GNPTAB, the gamma subunit facilitates the transfer of GlcNAc-1-phosphate to mannose residues on nascent lysosomal hydrolases. This M6P tag is subsequently recognized by cation-independent (MPR300) and cation-dependent (MPR46) mannose-6-phosphate receptors in the trans-Golgi network, directing enzymes such as cathepsin D and beta-glucuronidase to lysosomes. GNPTG expression is transcriptionally regulated by TFEB, the master regulator of lysosomal biogenesis. Loss of GNPTG disrupts M6P formation, impairing receptor-mediated sorting and leading to hypersecretion of lysosomal enzymes and compromised lysosomal function.
In the NCI-H1975 lung adenocarcinoma context, GNPTG knockout can be exploited to dissect the contribution of lysosomal enzyme trafficking to cancer cell metabolism, stress resistance, and autophagy. NCI-H1975 cells rely on autophagy as a survival mechanism, and proper lysosomal acidification and protease delivery are essential for autophagic flux. Disruption of the GNPTG-dependent M6P pathway in this model can be used to engineer mucolipidosis III gamma-like phenotypes, providing a platform for studying lysosomal storage disorders in a cancer background. The knockout cells also offer a system to investigate how impaired lysosomal targeting influences tumor growth pathways, EGFR degradation, and drug sensitivity.
Researchers can employ this model in a variety of experimental contexts, including the study of lysosomal enzyme trafficking, autophagy flux assays using LC3 turnover or tandem fluorescent reporters, cathepsin activity measurements, and lysosomal pH assessment with pH-sensitive dyes. Western blotting for mature versus pro-forms of cathepsin D or beta-glucuronidase can quantify processing defects, while M6P-specific ELISA or immunofluorescence for LAMP1 and MPRs allows visualization of altered lysosomal morphology and receptor distribution. These tools enable detailed interrogations of TFEB-mediated gene programs, effects on autophagic clearance of protein aggregates, and crosstalk between metabolic stress and lysosomal function in cancer cells. For additional information or to request this knockout cell product, please contact Ascent Research.
