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Interaction between epidermal growth factor receptor and cyclooxygenase 2mediated pathways and its implications for the chemoprevention of head and neck cancer
1 Department of Hematology/Oncology, Winship Cancer Institute, Emory University and 2 Quest Diagnostics, Atlanta, Georgia
Requests for reprints: Zhuo (Georgia) Chen, Department of Hematology/Oncology, Winship Cancer Institute, Emory University, Room 3086, 1365-C Clifton Road, Atlanta, GA 30322. E-mail: georgia_chen{at}emoryhealthcare.org
| Abstract |
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| Introduction |
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3% of all new cancers in the United States (1), and 90% of these are squamous cell carcinoma [head and neck squamous cell carcinoma (HNSCC)]. Due to its location and anatomic complexity, HNC causes almost inevitable functional and social impairment even before it becomes life threatening. Despite great advances in therapy, the overall survival rate for patients with HNC has not improved significantly, emphasizing the importance of preventive intervention (24). Chemoprevention can be defined as the use of specific agents to suppress, reverse, or prevent carcinogenesis, thus stopping the progression to invasive cancer by modulating the carcinogenic process or by removal (apoptosis) of premalignant cells (5, 6). Recently, the concept of chemoprevention has been substantially incorporated into cancer treatment goals. Progress in clinical trials has shown that the combined preventive approach is more effective than single-agent chemoprevention.
This review will briefly summarize chemopreventive approaches in HNSCC before highlighting a novel and promising chemopreventive modality combining cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors.
| Chemoprevention for HNC |
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HNSCC has been one of the main models for chemopreventive approaches and important issues have been learned from chemopreventive clinical trials. The most extensively studied chemopreventive agents in HNC areretinoids (11). The first randomized clinical trial was conducted by Hong et al. (11) using a high dose of 13-cis-retinoic acid (13-cRA) for a short period in patients with oral premalignant lesions, which showed significant clinical and pathologic responses. In spite of the encouraging results, this trial raised two important issues common in chemopreventive clinical trials. Dose-related toxicity was an important obstacle to treating patients on a long-term basis, and the remission induced by short-term treatment did not last long after cessation of treatment. This observation led to a subsequent low-dose maintenance trial. Lippman et al. (5) treated patients with oral premalignant lesions with high-dose 13-cRA for 3 months and switched to either low-dose 13-cRA or ß-carotene for maintenance. Although the results showed that using low-dose 13-cRA for maintenance could effectively repress disease progression, the long-term follow-up failed to show a difference in the cancer development rate in both groups (11). In terms of prevention of second primary tumor, the first phase III clinical trial using 13-cRA showed a statistically significant suppression of second primary tumor, although there was no significant difference in survival. Subsequent randomized clinical trials using retinoids have failed to show a difference in the development of second primary tumor or survival (11).
Obtaining long-lasting efficacy with low toxicity has been an important issue, provoking combinations of retinoids with other agents or searches for new chemopreventive agents. Other chemopreventive agents that have shown preventive effects include selenium and vitamin E. Recently, Papadimitrakopoulou et al. (12) reported that a combination of 13-cRA, vitamin E, and IFN-
restored advanced laryngeal premalignant lesions. Shin et al. (13, 14) showed that the same combination suppressed the development of second primary tumor and/or recurrence, and achieved an excellent survival rate in stage III/IV HNSCC, making this a promising combination chemopreventive approach. With a better understanding of relevant molecular changes in each carcinogenic step of HNC and increased availability of specific molecular targeting agents, chemoprevention in HNC has evolved to a new era. New agents in this context include COX inhibitors, EGFR tyrosine kinase inhibitors, farnesyl transferase inhibitors, and others (11).
| Rationale for Blocking COX-2 and EGFR Pathways in Chemoprevention of HNC |
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COX-2 Pathway in Carcinogenesis
COX-1 and COX-2 catalyze prostanoid synthesis from arachidonic acid. COX-1 is constitutively expressed in nearly all normal tissues and has a beneficial housekeeping role. COX-2 is undetectable (or at low levels) in most normal tissues but is rapidly induced in response to inflammatory or mitogenic stimuli, including cytokines, growth factors, and tumor promoters (24, 25).
COX-2 has been implicated in carcinogenesis ever since the discovery that intake of nonsteroidal anti-inflammatory drugs that inhibit COX activity also decrease the relative risk for development of colorectal cancer (26). There is also direct evidence for the carcinogenic role of COX-2. Oshima et al. (27) showed that selective genetic elimination of COX-2 protected APC tumor suppressor genedeleted mice from developing intestinal tumors. In humans, COX-2 overexpression has been found in premalignant and malignant lesions in several tumors (17, 18, 25; for review, see 28). In HNC, there is a stepwise increase in COX-2 expression through the normal, hyperplastic, dysplastic, and invasive carcinoma stages, suggesting its carcinogenic role in HNC (17, 18, 29).
COX-2 overexpression contributes to many aspects of carcinogenesis, such as inhibition of apoptosis, promotion of cell proliferation, induction of angiogenesis, and increasing invasiveness, mainly through increasing the amount of prostaglandins, including prostaglandin E2 (PGE2), PGF2
, PGD2, TXA2, PGI2, and PGJ2 (28, 30). Prostaglandins exert their effect mainly by binding to G-proteincoupled receptors, including EP-1, EP-2, EP-3, and EP-4, on cell surfaces (for review, see ref. 31). Each is specifically recognized by certain prostaglandins and activates signaling transduction from extracellular signal regulated kinase (32), phosphatidyl inositol 3-kinase/AKT, and cyclic AMP/protein kinase A (3235). Alternatively, cyclopentenone prostaglandins, such as PGJ2, can bind to the nuclear transcription factor peroxisome proliferator-activated receptor, which regulates expression of several genes involved in cell proliferation (36).
EGFR Signaling Pathway in Cancer Progression
EGFR, a surface receptor with intrinsic tyrosine kinase activity, is one of several known pivotal intermediates in many epithelial malignancies (37). It belongs to the erbB growth factor receptor family. The ligands binding to the extracellular domain of EGFR induce homodimerization of EGFR or heterodimerization with other members of the erbB growth factor receptor family, activating the intrinsic tyrosine kinase and its downstream signaling molecules (38). Potential EGFR downstream signaling pathways include Ras/mitogen-activated protein kinase, phosphatidyl inositol 3-kinase, phospholipase C
, the Src kinase family, Janus kinase, signal transducers, activators of transcription, and others (39). Activation of EGFR is involved in pertinent pleiotropic cellular processes, such as cell proliferation, apoptosis, differentiation, angiogenesis, and motility (3743).
Overexpression of EGFR has been frequently reported in human malignant neoplasms (44). In HNC, expression of EGFR and its ligands, transforming growth factor-
or epidermal growth factor, are up-regulated in histologically normal epithelium adjacent to invasive cancer compared with control normal epithelium in individuals without cancer. Dysplastic lesions overexpress EGFR, and invasive cancer displays a more jumped-up pattern of overexpression (19, 20). All this implicates the EGFR signaling pathway in the early stages of head and neck carcinogenesis and progression. EGFR overexpression is also associated with a poorer prognosis in HNC patients (45).
Interaction between EGFR and COX-2 Pathways
Whereas the pathways by which EGFR and COX-2 contribute to carcinogenesis have been separately considered and targeted, increasing evidence indicates a tight connection between these two pathways (Fig. 1).
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and epidermal growth factor, ligands of EGFR, were found to induce COX-2 expression (4650). Expression of COX-2 is regulated at both the transcriptional and posttranscriptional level. The signaling pathway involved in COX-2 induction via EGFR varies depending on the type of cells and inducers, but the ras/raf/mitogen-activated protein kinase signaling pathways mainly contribute to both increased transcriptional and posttranscriptional control. One explanation for the linkage between EGFR/mitogen-activated protein kinase and transcriptional activation of COX-2 may be the activation of transcription factors such as cyclic AMP response element-binding protein/activating transcription factor and activator protein-1 by mitogen-activated protein kinase signaling (25, 46, 51, 54). Binding sites for these transcription activators have been identified in the COX-2 promoter region.
On the other hand, COX-2 induces transactivation or increased expression of EGFR (55, 56). Transactivation of EGFR by PGE2, a major prostaglandin involved in carcinogenesis, has been well documented but the process seems to be quite complex and cell type dependent. Pai et al. (56) showed that PGE2 transactivated EGFR and triggered the activation of extracellular signal regulated kinase-2 pathways in normal gastric epithelial cells and colon cancer cells, inducing cell proliferation in vitro and in vivo. The G-protein coupled receptor, to which the major prostanoids receptors belong, is involved in EGFR transactivation. The mechanism by which G-protein coupled receptor mediates the transactivation of EGFR has not been clearly defined but the release of EGFR ligand by Src-activated transmembrane metalloproteinase has been suggested (31, 57). Consistent with these findings, Pai et al. (56) observed that PGE2-mediated transactivation of EGFR also involved transforming growth factor-
, likely released by Src-activated metalloproteinase. Complicating these findings, Buchanan et al. (58) reported that the transactivation of EGFR by PGE2 occurred via an intracellular Src-mediated event but not through the release of an extracellular epidermal growth factor-like ligand in colon cancer cell lines. On the other hand, Shao et al. (34) showed that PGE2 activated EGFR through the induction of increased amphiregulin expression, one of the EGFR ligands. They showed that PGE2 activated the cyclic AMP/protein kinase A pathway, which induced expression of amphiregulin in a colon cancer cell line. Induction of EGFR expression by overexpression of COX-1 or COX-2 was reported by Kinoshita et al. (55) in a human colon cancer cell line. There is a recent evidence for EGFR and proliferator-activated receptor transactivation through an Src-dependent pathway (59).
A direct collaborative effect between PGE2 and EGFR on tumor cell phenotypes, such as invasion and proliferation, is also well documented. Shao et al. showed this collaboration between COX-2/PGE2 and EGFR pathways (34, 60), observing synergistic induction of amphiregulin by PGE2 and transforming growth factor-
(34). In a follow-up study, they showed that activation of both PGE2 and EGFR signaling pathways synergistically promoted the growth and migration of colon cancer cells (60). Pai et al. (61) reported that PGE2 enhancement of invasiveness in a colon cancer cell line was mediated by transactivation of c-Met-R (hepatocyte growth factor receptor), partly through the transactivation of EGFR. Buchanan et al. (58) made a similar observation, showing that PGE2-induced cell migration was mediated by the transactivation of EGFR, and associated with intracellular Src activation in colon cancer cells.
It is worth noting that COX inhibitor repressed the EGFR-related pathway and in turn, EGFR inhibitor repressed COX-2 expression, indirectly suggesting their interaction (62, 63). COX inhibitors were reported to block the cell proliferation induced by epidermal growth factor in NIH 3T3 cells, which could be reversed by adding exogenous PGE2 (62). Gefitinib, an EGFR inhibitor, showed inhibition of COX-2 expression in a HNSCC cell line (63). In addition, celecoxib, a selective COX-2 inhibitor, showed a protective effect against HER-2/neu-induced experimental breast cancer, indirectly suggesting a relationship between the epithelial growth factor receptor family and COX-2 (64).
On top of their known interactions, both the EGFR and COX-2 pathways affect the same aspects of carcinogenesis, such as inhibition of apoptosis and induction of angiogenesis. The conclusion that the EGFR and COX-2 pathways directly or indirectly collaborate in pertinent carcinogenic pathways seems justified.
| Therapeutic Implication of Targeting COX-2 and EGFR-Mediated Pathways in Chemoprevention |
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Based on these promising results, many clinical trials of chemoprevention using various COX-2 inhibitors have been conducted in various organs, although mostly in colon. The first chemopreventive trial using a selective COX-2 inhibitor in humans was conducted on familial adenomatous polyposis patients. Familial adenomatous polyposis patients were treated with celecoxib 400 mg bid for 6 months and were compared with a placebo-treated group for their polyp burden. A significant reduction in polyp burden was observed in the celecoxib-treated group (21). Observing the data from this study, the Food and Drug Administration approved celecoxib as an adjuvant therapy for familial adenomatous polyposis patients. Currently, phase II clinical trials are under way to evaluate COX-2 inhibitors for the prevention of recurrence or development of second primary tumor in early-stage HNC patients and the prevention of cancer in patients with oral leukoplakia or dysplasia, using celecoxib.
However, notable cardiovascular toxicity was reported for specific COX-2 inhibitors recently, which resulted in reevaluation of the clinical use of COX-2 inhibitors (79).3 Studies of COX-2specific inhibitors, including celecoxib, showed that COX-2 inhibitors increased the thromboembolic cardiovascular risks. A hypothetical explanation is that, unlike nonselective nonsteroidal anti-inflammatory drugs, COX-2 inhibitors could not inhibit platelet aggregation (80, 81). Due to concerns about cardiovascular complications associated with long-term use of COX-2 inhibitors, in December 2004, the National Cancer Institute announced the early cessation of a large colorectal cancer prevention clinical trial with celecoxib.3 But in April 2005, the Food and Drug Administration announced restricted use of nonsteroidal anti-inflammatory drugs, including celecoxib, by providing revised labels to include more specific information about the potential cardiovascular and gastrointestinal risks.4
EGFR as a Target of Therapeutic or Chemopreventive Agents
A variety of strategies have been developed to block EGFR specifically, including monoclonal antibodies, tyrosine kinase inhibitors, ligand-linked immunotoxins, and antisense approaches (37, 82, 83). Among those strategies, monoclonal antibodies, such as IMC-225 (Cetuximab), and tyrosine kinase inhibitors, such as ZD1839 (Iressa or Gefitinib), and OSI-774 (Tarceva or Erlotinib) have shown promising efficacy and are currently being used in clinical studies singly or in combination with other chemotherapeutic agents or radiotherapy. The antineoplastic effects of EGFR inhibitors include inhibition of cell cycle progression, induction of apoptosis, inhibition of angiogenesis, and decreasing metastasis (40, 84). In HNC, EGFR inhibition also showed growth inhibition and inhibition of metastasis in in vitro and in vivo experiments (8489).
Like other anticancer agents, EGFR inhibitor toxicity was also reported. The main toxic effects of EGFR tyrosine kinase inhibitors, such as OSI-774 and ZD1839, include headache, diarrhea, and skin rash (22, 90, 91). Rare association with interstitial lung disease was also observed using ZD1839 (92, 93).
Combined Chemopreventive Therapy Using COX-2 and EGFR Inhibitors
Because the underlying genetic mechanisms of many malignant neoplasms are possibly multipath processes combined with complex cross-talk between pathways, specific blocking of single molecular targets would not outwit the variability and complexity of genetic alterations in cancer. Combined treatments using appropriate multiagents may be more effective than single agent treatments. In terms of chemoprevention, combining low doses of drugs too toxic for single use may result in negligible toxicity while eluding drug resistance, resulting in an elegant strategy that is both effective and safe.
Considering the tight connection of the COX-2 and EGFR pathways, the combination of their particular inhibitors may block both pathways in a synergistic or additive manner. This idea has been supported by in vitro and in vivo studies combining COX-2 and EGFR inhibitors (Table 1). Tortora et al. (94) showed a supra-additive inhibitory effect on tumor growth and angiogenesis by combined treatment with SC-236 (COX-2 inhibitor), ZD1839, and protein kinase A antisense in human colon and breast cancer cell lines and a colon cancer xenograft. We also observed a synergistic growth-inhibitory effect by combining celecoxib and ZD1839 in HNSCC in vitro (95) and in vivo (96). The combination of celecoxib and ZD1839 augmented G1 cell cycle arrest and further suppressed phosphorylation of EGFR downstream signaling molecules, such as EGFR, extracellular signal regulated kinase, and AKT. This synergistic growth inhibitory effect was also observed in a breast cancer cell line. De Luca et al. (97) found a synergistic growth inhibitory effect on breast cancer cell lines with a combination of rofecoxib and ZD1839. As with our observation, this effect was associated with significant further inactivation of AKT and extracellular signal regulated kinase.
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20 polyps, nearly half the mice treated with both agents developed no polyps at all. In HNC, we observed that pretreatment with celecoxib and ZD1839 before tumor injection results in significant tumor growth delay and inhibition compared with control and single-drugtreated groups (96). The same effect could usually be achieved by at least more than double dose of ZD1839 alone (50 mg/kg in the combination versus 150 mg/kg as a single drug; refs. 96, 99). Combining COX-2 and EGFR inhibitors seems to impede or avert several carcinogenic steps with lower toxicity. As observed previously, cellular proliferation is also more efficiently repressed by this combinational strategy. It may inhibit further progression of genetic instability and make abnormal cells more vulnerable to apoptotic cell death. Synergistic inhibition of angiogenesis has also been achieved. It is rational to expect that inhibiting both pathways with a low dose of each inhibitor would reduce toxicity, because the toxicity from COX-2 inhibitor and EGFR inhibitor have unrelated mechanisms. Based on preclinical studies, several clinical trials using a combination of COX-2 and EGFR inhibitors are either ongoing or pending activation. Two phase I trials using COX-2 and EGFR tyrosine kinase inhibitors were reported in the American Society of Clinical Oncology meetings of last year and this year (100, 101). The first trial enrolled 12 patients with advanced metastatic and recurrent HNSCC (100). Three of nine evaluable patients showed partial response with no dose-limiting toxicities up to the reporting date. The second trial involved 15 patients with advanced NSCLC (101). The combined drugs were well tolerated. Four of 12 evaluable patients showed partial response and three showed stable disease with no unanticipated toxicities. At present, a randomized multicenter trial using celecoxib and EKB-569 (EGFR tyrosine kinase inhibitor) for preventing oral cancer in patients with oral leukoplakia is pending at the M. D. Anderson Cancer Center (28). We are also planning phase I/II chemopreventive clinical trials using a combination of OSI-774 (Tarceva) and celecoxib for former smokers with premalignant lesions and patients with early stage (stage I/II) HNSCC to prevent HNSCC and second primary and recurrent tumors, respectively. Once launched, these clinical trials will provide valuable information on toxicity, response rate, and appropriate biomarkers for using the combination of COX-2 and EGFR inhibitors in cancer clinics.
| Future Prospects and Conclusions |
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In conclusion, an expanding body of evidence shows tight interaction between the EGFR and COX-2 pathways, which may provide a target for a synergistic inhibitory effect on cancer cell growth using EGFR and COX-2 inhibitors in combination. This combination approach is a promising novel strategy for the chemoprevention of HNC, which may achieve more effective cancer prevention with less drug toxicity or drug resistance than monotherapy with either drug.
| Footnotes |
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The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
3 Department of Health and Human Services. NIH halts use of COX-2 inhibitor in large cancer prevention trial. NIH News, December 17, 2004. Available at http://www.nih.gov/news/pr/dec2004. ![]()
4 The Food and Drug Administration announces series of changes to the class of marketed nonsteroidal anti-inflammatory drugs. Food and Drug Administration News, April 7, 2005. Available at http://www.fda.gov/bbs/topics/news/2005. ![]()
Received 9/20/04; revised 7/13/05; accepted 7/15/05.
| References |
|---|
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|
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, 13-cis-retinoic acid, and
-tocopherol in locally advanced head and neck squamous cell carcinoma: novel bioadjuvant phase II trial. J Clin Oncol 2001;19:30107.
2a (IFN-
2a), 13-cis-retinoic acid (13-cRA), and
-tocopherol (
-TF) for locally advanced squamous cell carcinoma of the head and neck (SCCHN): long term follow-up. Proc Am Soc Clin Oncol 2003;22:496.
Lin DT, Subbaramaiah K, Shah JP, Dannenberg AJ, Boyle JO. Cyclooxygenase-2: a novel molecular target for the prevention and treatment of HNC. Head Neck 2002;24:7929.[CrossRef][Medline]
Ford AC, Grandis JR. Targeting epidermal growth factor receptor in HNC. Head Neck 2003;25:6773.[CrossRef][Medline]
Chan G, Boyle JO, Yang EK, et al. Cyclooxygenase-2 expression is up-regulated in squamous cell carcinoma of the head and neck. Cancer Res 1999;9:9914.
Renkonen J, Wolff H, Paavonen T. Expression of cyclooxygenase-2 in human tongue carcinoma and its precursor lesions. Virchows Arch 2002;440:5947.[CrossRef][Medline]
Shin DM, Ro JY, Hong WK, Hittleman WN. Dysregulation of epidermal growth factor receptor expression in premalignant lesions during head and neck tumorigenesis. Cancer Res 1994;54:31539.
and epidermal growth factor receptor protein expression in progression of premalignant lesions to head and neck squamous cell carcinoma. Clin Cancer Res 1998;4:1320.[Abstract]
Steinbach G, Lynch PM, Phillips RK, et al. The effect of celecoxib, a cyclooxygenase-2 inhibitor, in familial adenomatous polyposis. N Engl J Med 2000;342:194652.
716 knockout mice by inhibition of cyclooxygenase 2 (COX-2). Cell 1996;87:8039.[CrossRef][Medline]
Dannenberg AJ, Lippman SM, Mann JR, Subbaramaiah K, DuBois RN. Cyclooxygenase-2 and epidermal growth factor receptor: pharmacologic targets for chemoprevention. J Clin Oncol 2005;23:25466.
716 knockout mice. Nat Med 2001;7:104851.[CrossRef][Medline]
Shao J, Lee SB, Guo H, Evers BM, Sheng H. Prostaglandin E2 stimulates the growth of colon cancer cells via induction of amphiregulin. Cancer Res 2003;63:521823.
and transforming growth factor
in normal human epidermal keratinocytes and squamous carcinoma cells: role of mitogen-activated protein kinases. J Biol Chem 1999;274:2913848.
and phorbol ester. J Clin Invest 1994;93:4938.
Chen LC, Chen BK, Chang JM, Chang WC. Essential role of c-Jun induction and coactivator p300 in epidermal growth factor-induced gene expression of cyclooxygenase-2 in human epidermoid carcinoma A431 cells. Biochim Biophys Acta 2004;1683:3848.[Medline]
Kinoshita T, Takahashi Y, Sakashita T, Inoue H, Tanabe T, Yoshimoto T. Growth stimulation and induction of epidermal growth factor receptor by overproduction of cyclooxygenase 1 and 2 in human colon carcinoma cells. Biochim Biophys Acta 1999;438:12030.
Pai R, Soreghan B, Szabo IL, Pavelka M, Baatar D, Tarnawski AS. Prostaglandin E2 transactivates EGF receptor: a novel mechanism for promoting colon cancer growth and gastrointestinal hypertrophy. Nat Med 2002;8:28993.[CrossRef][Medline]
Luttrell LM, Daaka Y, Lefkowitz RJ. Regulation of tyrosine kinase cascades by G-protein coupled receptors. Curr Opin Cell Biol 1999;11:17783.[CrossRef][Medline]
Buchanan FG, Wang D, Bargiacchi F, DuBois RN. Prostaglandin E2 regulates cell migration via the intracellular activation of the epidermal growth factor receptor. J Biol Chem 2003;278:354517.
]-dependent suppression of helicobacter pyliori interference with gastric mucin synthesis. Inflammopharmacology 2004;12:17788.[CrossRef][Medline]
Shao J, Evers BM, Sheng H. Prostaglandin E2 synergistically enhances receptor tyrosine kinase-dependent signaling system in colon cancer cells. J Biol Chem 2004;279:1428793.This article has been cited by other articles:
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