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Updated: Aug 11, 2026
Evaluating the Effectiveness of Cancer Drug Sensitization In Vitro and In Vivo
Published on: February 6, 2015
Proteasome inhibition sensitizes non-small-cell lung cancer to gemcitabine-induced apoptosis
Chadrick E Denlinger1, Brian K Rundall, Michael D Keller
1Department of Thoracic and Cardiovascular Surgery, University of Virginia, Charlottesville, Virginia 22908-0679, USA.
Background:
My colleagues and I have previously shown that chemotherapy activates the antiapoptotic transcription factor nuclear factor (NF)-kappaB in non-small-cell lung cancer (NSCLC). We hypothesized that inhibition of NF-kappaB by using the proteasome inhibitor bortezomib (Velcade) would sensitize NSCLC to gemcitabine-induced apoptosis.
Methods:
Tumorigenic NSCLC cell lines (H157 and A549) were treated with nothing, gemcitabine, bortezomib, or both compounds. NF-kappaB activity was determined by nuclear p65 protein levels, electrophoretic mobility shift assays, and reverse transcription-polymerase chain reaction of the NF-kappaB-regulated genes interleukin-8, c-IAP2, and Bcl-xL. The p21 and p53 protein levels were determined in similarly treated cells. Cell-cycle dysregulation was assessed by fluorescence-activated cell sorting analysis. Cell death and apoptosis were quantified by clonogenic assays, caspase-3 activation, and DNA fragmentation. NSCLC A549 xenografts were generated and treated as noted previously. Tumor growth was assessed over a 4-week treatment period. Statistical analysis was performed with analysis of variance.
Results:
Gemcitabine enhanced nuclear p65 levels, NF-kappaB binding to DNA, and transcription of all NF-kappaB-regulated genes. Bortezomib inhibited each of these effects. Combined gemcitabine and bortezomib enhanced p21 and p53 expression and induced S-phase and G2/M cell-cycle arrests, respectively. Combined treatment killed 80% of the NSCLC cells and induced apoptosis, as determined by caspase-3 activation (p = 0.05) and DNA fragmentation (p = 0.02). NSCLC xenografts treated with combination therapy grew significantly slower than xenografts treated with gemcitabine alone (p = 0.02).
Conclusions:
Bortezomib inhibits gemcitabine-induced activation of NF-kappaB and sensitizes NSCLC to death in vitro and in vivo. This combined treatment strategy warrants further investigation and may represent a reasonable treatment strategy for select patients with NSCLC given the current clinical availability of both drugs.
Insights
Inhibition of nuclear factor-kappaB (NF-κB) with bortezomib sensitizes non-small-cell lung cancer (NSCLC) to gemcitabine, enhancing apoptosis and slowing tumor growth. This combination therapy shows promise for NSCLC treatment.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Therapeutics
Background:
- Chemotherapy activates nuclear factor-kappaB (NF-κB), an antiapoptotic transcription factor, in non-small-cell lung cancer (NSCLC).
- Inhibiting NF-κB may sensitize NSCLC to chemotherapy-induced apoptosis.
Purpose of the Study:
- To investigate if bortezomib, a proteasome inhibitor, can inhibit NF-κB and sensitize NSCLC to gemcitabine-induced apoptosis.
- To evaluate the efficacy of combined gemcitabine and bortezomib treatment in NSCLC cell lines and xenografts.
Main Methods:
- NSCLC cell lines (H157, A549) were treated with gemcitabine, bortezomib, or both.
- NF-κB activity, protein levels (p53, p21), cell-cycle progression, and apoptosis were assessed.
- NSCLC xenografts were treated, and tumor growth was monitored over 4 weeks.
Main Results:
- Gemcitabine increased NF-κB activity; bortezomib inhibited this effect.
- Combined treatment enhanced p53 and p21 expression, induced cell-cycle arrest, and led to 80% NSCLC cell death via apoptosis.
- Combination therapy significantly slowed xenograft tumor growth compared to gemcitabine alone.
Conclusions:
- Bortezomib effectively inhibits gemcitabine-induced NF-κB activation in NSCLC.
- The combination of bortezomib and gemcitabine demonstrates significant anti-cancer activity in vitro and in vivo.
- This combined treatment strategy warrants further clinical investigation for NSCLC patients.
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