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Updated: Jun 20, 2026
DNA Vector-based RNA Interference to Study Gene Function in Cancer
Published on: June 4, 2012
A loss-of-function RNA interference screen for molecular targets in cancer
Vu N Ngo1, R Eric Davis, Laurence Lamy
1Metabolism Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Abstract:
The pursuit of novel therapeutic agents in cancer relies on the identification and validation of molecular targets. Hallmarks of cancer include self-sufficiency in growth signals and evasion from apoptosis; genes that regulate these processes may be optimal for therapeutic attack. Here we describe a loss-of-function screen for genes required for the proliferation and survival of cancer cells using an RNA interference library. We used a doxycycline-inducible retroviral vector for the expression of small hairpin RNAs (shRNAs) to construct a library targeting 2,500 human genes. We used retroviral pools from this library to infect cell lines representing two distinct molecular subgroups of diffuse large B-cell lymphoma (DLBCL), termed activated B-cell-like DLBCL and germinal centre B-cell-like DLBCL. Each vector was engineered to contain a unique 60-base-pair 'bar code', allowing the abundance of an individual shRNA vector within a population of transduced cells to be measured using microarrays of the bar-code sequences. We observed that a subset of shRNA vectors was depleted from the transduced cells after three weeks in culture only if shRNA expression was induced. In activated B-cell-like DLBCL cells, but not germinal centre B-cell-like DLBCL cells, shRNAs targeting the NF-kappaB pathway were depleted, in keeping with the essential role of this pathway in the survival of activated B-cell-like DLBCL. This screen uncovered CARD11 as a key upstream signalling component responsible for the constitutive IkappaB kinase activity in activated B-cell-like DLBCL. The methodology that we describe can be used to establish a functional taxonomy of cancer and help reveal new classes of therapeutic targets distinct from known oncogenes.
Insights
This study developed a novel RNA interference screen to identify cancer survival genes. The screen highlighted the NF-kappaB pathway and CARD11 as crucial targets in activated B-cell-like diffuse large B-cell lymphoma.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Cancer therapy development requires identifying and validating molecular targets.
- Genes regulating cancer hallmarks like self-sufficiency in growth signals and apoptosis evasion are prime therapeutic targets.
- Diffuse large B-cell lymphoma (DLBCL) comprises distinct molecular subgroups, including activated B-cell-like (ABC) and germinal center B-cell-like (GCB) DLBCL, with differing survival mechanisms.
Purpose of the Study:
- To perform a functional loss-of-function screen to identify genes essential for cancer cell proliferation and survival.
- To investigate the differential requirements of genes in ABC-DLBCL versus GCB-DLBCL.
- To uncover novel therapeutic targets for cancer, particularly DLBCL.
Main Methods:
- Construction of a doxycycline-inducible retroviral RNA interference (RNAi) library targeting 2,500 human genes.
- Infection of ABC-DLBCL and GCB-DLBCL cell lines with the RNAi library, with each vector containing a unique barcode for abundance measurement.
- Measurement of shRNA vector abundance via barcode microarray analysis after three weeks of induced expression to identify depleted shRNAs, indicating essential genes.
Main Results:
- A subset of shRNA vectors was specifically depleted in transduced cells upon induction, signifying their role in cell survival or proliferation.
- In ABC-DLBCL cells, shRNAs targeting the NF-kappaB pathway were significantly depleted, confirming its critical role in this subtype.
- The screen identified CARD11 as a key upstream signaling component responsible for constitutive IkappaB kinase activity in ABC-DLBCL.
Conclusions:
- The RNAi screening methodology is effective for establishing a functional taxonomy of cancer.
- The study identified the NF-kappaB pathway and CARD11 as critical vulnerabilities in ABC-DLBCL.
- This approach can reveal novel classes of therapeutic targets beyond known oncogenes for cancer treatment.
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