The HERC4 Knockout NCI-H1975 Polyclonal Cells are a CRISPR/Cas9-edited polyclonal knockout cell population designed to disrupt HERC4 expression in the NCI-H1975 human lung adenocarcinoma cell line. This cryopreserved pool harbors heterogeneous gene disruptions, avoiding clonal selection bias while enabling loss-of-function studies of HERC4-dependent processes without monoclonal artifacts.
NCI-H1975 is a widely used NSCLC model harboring the EGFR L858R mutation, along with TP53 and CDKN2A alterations, making it highly relevant for investigating EGFR-driven lung adenocarcinoma mechanisms and therapeutic responses. These adherent epithelial cells provide a clinically pertinent background for studying how HERC4 deficiency impacts oncogenic signaling, proteostasis, and drug sensitivity in lung cancer.
HERC4 is an E3 ubiquitin ligase that functions within the ubiquitin-proteasome system (UPS). It physically interacts with the UBE2D family of E2 ubiquitin-conjugating enzymes (UBE2D1, UBE2D2, UBE2D3) to catalyze substrate ubiquitination. Upstream signals such as cell stress and DNA damage regulate HERC4 activity, leading to polyubiquitin chain assembly on target proteins, which are then shuttled to the 26S proteasome for degradation. Known substrates include cell cycle regulators; thus, HERC4 plays a pivotal role in modulating protein quality control and cell cycle progression. The canonical pathway involves sequential actions of E1, E2, and HERC4 E3 ligase, ultimately engaging the 20S core and 19S regulatory particles of the proteasome.
In the lung adenocarcinoma background, HERC4 knockout likely disrupts normal degradation of specific substrates, causing their accumulation and possibly leading to cell cycle dysregulation and altered protein homeostasis. Because NSCLC cells often depend on the UPS for growth and survival, HERC4 loss may confer synthetic lethality with proteasome inhibitors or other targeted agents. This polyclonal model captures a spectrum of editing outcomes, reflecting heterogeneity similar to that observed in tumors, and provides a robust platform to evaluate biological responses without clonal bias. It is particularly suited for probing how UPS perturbations intersect with EGFR-mutant signaling networks.
Typical applications include identification of HERC4 substrates via co-immunoprecipitation coupled with mass spectrometry, measurement of proteasome activity, cell cycle analysis by flow cytometry, and proliferation assays (MTT or CellTiter-Glo). Western blotting can assess global ubiquitination patterns, while RNA-seq permits transcriptome-wide profiling. The model also enables drug screening for UPS inhibitors and functional rescue experiments. For technical inquiries, custom assay development, or bulk ordering, please contact Ascent Research.
