This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Sloss, C. M. Articles by Cusack, J. C. PubMed PubMed Citation Articles by Sloss, C. M. Articles by Cusack, J. C., Jr.

Proteasome Inhibition Activates Epidermal Growth Factor Receptor (EGFR) and EGFR-Independent Mitogenic Kinase Signaling Pathways in Pancreatic Cancer Cells

Authors' Affiliations: ¹ Division of Surgical Oncology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts and ² Nereus Pharmaceuticals, San Diego, California

Requests for reprints: James C. Cusack, Jr., Division of Surgical Oncology, Massachusetts General Hospital, Yawkey 7th Floor, 55 Fruit Street, Boston, MA 02114. Phone: 617-724-4093; Fax: 617-724-3895; E-mail: jcusack{at}partners.org.

Purpose: In the current study, we investigate the activation of antiapoptotic signaling pathways in response to proteasome inhibitor treatment in pancreatic cancer and evaluate the use of concomitant inhibition of these pathways to augment proteasome inhibitor treatment responses.

Experimental Design: Pancreatic cancer cell lines and mouse flank xenografts were treated with proteasome inhibitor alone or in combination with chemotherapeutic compounds (gemcitabine, erlotinib, and bevacizumab), induction of apoptosis and effects on tumor growth were assessed. The effect of bortezomib (a first-generation proteasome inhibitor) and NPI-0052 (a second-generation proteasome inhibitor) treatment on key pancreatic mitogenic and antiapoptotic pathways [epidermal growth factor receptor, extracellular signal-regulated kinase, and phosphoinositide-3-kinase (PI3K)/AKT] was determined and the ability of inhibitors of these pathways to enhance the effects of proteasome inhibition was assessed in vitro and in vivo.

Results: Our data showed that proteasome inhibitor treatment activates antiapoptotic and mitogenic signaling pathways (epidermal growth factor receptor, extracellular signal-regulated kinase, c-Jun-NH₂-kinase, and PI3K/AKT) in pancreatic cancer. Additionally, we found that activation of these pathways impairs tumor response to proteasome inhibitor treatment and inhibition of the c-Jun-NH₂-kinase and PI3K/AKT pathways increases the antitumor effects of proteasome inhibitor treatment.

Conclusion: These preclinical studies suggest that targeting proteasome inhibitor–induced antiapoptotic signaling pathways in combination with proteasome inhibition may augment treatment response in highly resistant solid organ malignancies. Further evaluation of these novel treatment combinations in clinical trials is warranted.