Cyclooxygenase-2 (COX-2) Levels Before and After Chemotherapy: A Study in Rectal Cancer

Cyclooxygenase-2 mediates gefitinib resistance in non-small cell lung cancer through the EGFR/PI3K/AKT axis

Gefitinib is a potent inhibitor of EGFR and represents the front-line treatment for non-small cell lung cancer (NSCLC) therapeutics. However, NSCLC patients are prone to develop acquired resistance through as yet, undefined mechanisms of resistance. Here, we investigated the role of COX-2 during gefitinib resistance in NSCLC cells and revealed its underlying mechanism(s) of action. We report the upregulation of COX-2 in gefitinib-resistant NSCLC tissues and cells, which is associated with poor prognosis. In vitro assays in NSCLC cells (PC9/GR) showed that COX-2 facilitates gefitinib resistance in NSCLC cells through its effects on P-gp, MRP1, and BCRP, and cancer cell migration and invasion. In vivo, COX-2 silencing could repress tumor growth. We found that the overexpression of COX-2 enhances the transcription of MMP-2, MMP-7, and MMP-9 which mediates PI3K-AKT activation. In summary, we demonstrate that COX-2 mediates the gefitinib resistance of NSCLC cells through its interaction with EGFR and the PI3K-AKT axis. This highlights COX-2 as a novel molecular target for NSCLC.

Breast cancer cell cyclooxygenase-2 expression alters extracellular matrix structure and function and numbers of cancer associated fibroblasts

Cyclooxygenase-2 (COX-2) is a critically important mediator of inflammation that significantly influences tumor angiogenesis, invasion, and metastasis. We investigated the role of COX-2 expressed by triple negative breast cancer cells in altering the structure and function of the extracellular matrix (ECM). COX-2 downregulation effects on ECM structure and function were investigated using magnetic resonance imaging (MRI) and second harmonic generation (SHG) microscopy of tumors derived from triple negative MDA-MB-231 breast cancer cells, and a derived clone stably expressing a short hairpin (shRNA) molecule downregulating COX-2. MRI of albumin-GdDTPA was used to characterize macromolecular fluid transport in vivo and SHG microscopy was used to quantify collagen 1 (Col1) fiber morphology. COX-2 downregulation decreased Col1 fiber density and altered macromolecular fluid transport. Immunohistochemistry identified significantly fewer activated cancer associated fibroblasts (CAFs) in low COX-2 expressing tumors. Metastatic lung nodules established by COX-2 downregulated cells were infrequent, smaller, and contained fewer Col1 fibers.COX-2 overexpression studies were performed with tumors derived from triple negative SUM-149 breast cancer cells lentivirally transduced to overexpress COX-2. SHG microscopy identified significantly higher Col1 fiber density in COX-2 overexpressing tumors with an increase of CAFs. These data expand upon the roles of COX-2 in shaping the structure and function of the ECM in primary and metastatic tumors, and identify the potential role of COX-2 in modifying the number of CAFs in tumors that may have contributed to the altered ECM.

PTGS2 (Cyclooxygenase-2) expression and survival among colorectal cancer patients: a systematic review

BACKGROUND

Studies have examined whether tumor expression of PTGS2 (also known as COX-2), an enzyme inhibited by nonsteroidal anti-inflammatory drugs such as aspirin, is associated with prognosis in patients with colorectal cancer. However, results to date have been mixed.

METHODS

Using terms for PTGS2 and colorectal cancer, the Medline, Embase, and Web of Science databases were systematically searched for studies published, in any language, until December 2011. Random effects meta-analyses were used to calculate pooled HRs [95% confidence intervals (CI)] for the association between PTGS2 expression and tumor recurrence, colorectal cancer-specific survival, and overall survival.

RESULTS

In total, 29 studies, which had prognostic data on 5,648 patients, met the inclusion criteria. PTGS2-positive patients were at an increased risk of tumor recurrence (n = 9 studies; HR, 2.79; 95% CI, 1.76-4.41; P < 0.001) and had poorer colorectal cancer-specific survival (n = 7; HR, 1.36; 95% CI, 1.02-1.82; P = 0.04). However, there was funnel plot asymmetry, possibly due to publication bias, for the association with cancer-specific survival but less so for recurrence. PTGS2 expression was not associated with overall survival [(n = 16; pooled unadjusted HR, 1.30; 95% CI, 0.94-1.79; P = 0.11) and (n = 9; pooled adjusted HR, 1.02; 95% CI, 0.72-1.45; P = 0.91)].

CONCLUSIONS

PTGS2 expression was associated with an increased risk of tumor recurrence and poorer colorectal cancer-specific survival but not overall survival among patients with colorectal cancer. However, confounding by tumor characteristics such as tumor stage seems likely.

IMPACT

There is insufficient evidence to recommend PTGS2 expression as a prognostic marker in patients with colorectal cancer. Furthermore, studies providing adjusted results are required.

The effect of cyclooxygenase-2 expression on tumor volume response in patients treated with radiotherapy for uterine cervical cancer

We investigated the correlation between Cyclooxygenase-2 (COX-2) expression and the tumor response in patients with cervical cancer that were treated with curative radiotherapy (RT). Fifty-seven patients with squamous cell carcinoma were treated with concurrent radiochemotherapy (CRCT, n=29) or RT alone (n=28). The response of each patient was evaluated by three serial Magnetic Resonance Imaging examinations: before the start of RT, at four weeks after the start of RT (mid-RT) and at four weeks after the completion of RT (post-RT). Forty-three patients had positive COX-2 expression. The COX-2 negative patients achieved a higher rate of complete response (CR) at mid-RT than did the COX-2 positive patients (28.6% vs. 7.0%, P=0.054), but not at post-RT (64.3% vs. 69.8%). The initial tumor volume was a significant predictor of CR at mid-RT (P=0.003) and post-RT (P=0.004). The multivariate analysis showed that the initial tumor volume (at mid-RT and post-RT) and CRCT (at post-RT) were significant predictors of CR; however, the COX-2 expression was not. In conclusion, the COX-2 expression status has no significant correlation with the tumor response. Further studies on the changes in COX-2 expression levels during RT may be helpful for determination of its role in the tumor response to treatment and patient prognosis.

Cyclooxygenase-2 (COX-2) negatively regulates expression of epidermal growth factor receptor and causes resistance to gefitinib in COX-2-overexpressing cancer cells

Overexpression of cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) has been detected in many types of cancer. Although COX-2 and EGFR are closely related to each other, the exact mechanism of COX-2 in tumors has not been well understood. In this study, we investigated the relationship between COX-2 and EGFR in cancer cells. Using two cell lines stably overexpressing COX-2 (HCT-116-COX-2 and H460-COX-2) and a stable line of COX-2 knockdown MOR-P cells, we analyzed patterns of COX-2 and EGFR expression. To observe the effects of COX-2 on EGFR expression and activity, we did comparative analyses after treatment with various drugs (EGF, celecoxib, prostaglandin E(2), gefitinib, Ro-31-8425, PD98059, and SP600125) in HCT-116-Mock versus HCT-116-COX-2 cells and H460-Mock versus H460-COX-2 cells. Overexpression of COX-2 specifically down-regulated EGFR expression at the level of transcription. COX-2-overexpressing cells have a decreased sensitivity to gefitinib. COX-2 induced activation of extracellular signal-regulated kinase (ERK) and c-Jun NH(2)-terminal kinase (JNK) but suppressed Akt activation. JNK inhibition by SP600125, a specific JNK inhibitor, resulted in restoration of EGFR levels in COX-2-overexpressing cells, whereas ERK inhibition by PD98059 did not. Overexpressed COX-2 negatively regulates EGFR expression via JNK activation, leading to gefitinib resistance. COX-2 may also regulate ERK activity independently of EGFR. Therefore, resistance of COX-2-overexpressing cells to gefitinib may be due to decreased expression of EGFR by JNK activation and EGFR-independent elevation of ERK activity by COX-2. The ability of COX-2 to inhibit EGFR expression and gefitinib effects may have significance in clinical cancer therapy.

Morphological features and molecular markers in rectal cancer from 95 patients included in the European Organisation for Research and Treatment of Cancer 22921 trial: prognostic value and effects of preoperative radio (chemo) therapy

In this study, the prognostic and/or predictive value of different proteins (cyclo-oxygenase 2 (COX-2), Ki67 and cleaved cytokeratin (CK) 18) and fibro-inflammatory changes which might be of importance for the response to treatment were evaluated using tissue micro arrays. Samples were obtained from a subset of 95 patients included in the European Organisation for Research and Treatment of Cancer 22921 clinical trial, which randomised patients with rectal cancer to one of four arms treated with preoperative radiotherapy with or without pre- and/or postoperative chemotherapy. From our results, we can conclude that the addition of preoperative chemotherapy to radiotherapy led to significantly less COX-2 upregulation, less proliferation and more inflammation, as was seen in the resection specimen as well as less invasion and metastasis. For COX-2, Ki67 or cleaved CK18, no predictive or prognostic value could be identified. However, the fibro-inflammatory reaction after preoperative radiochemotherapy correlated with T-downstaging and seems to be an important factor for response.

Absence of cyclooxygenase-2 protein expression is a predictor of tumor regression in rectal cancer treated with preoperative short-term chemoradiotherapy

PURPOSE

Neoadjuvant chemoradiotherapy followed by total mesorectal excision has become the standard of care for patients with locally advanced rectal cancer. This study was designed to determine whether pretreatment cyclooxygenase-2 and p53 protein expression were predictors of histopathologic response in patients with rectal cancer treated with preoperative short-term chemoradiotherapy.

METHODS

Fifty-two patients with low rectal cancer received short-term preoperative chemoradiotherapy (20 Gy given in 5 daily doses of 4 Gy and concurrent administration of Tegafur/Uracil 400 mg/day), followed by total mesorectal excision. Cyclooxygenase-2 and p53 protein expression were measured by immunohistochemistry before and at the time of resection. Tumor regression grading was evaluated according to the criteria by Rodel (Grade 4, complete regression; Grade 3, regression >50 percent; Grade 2, 25-50 percent; Grade 1,<25 percent; and Grade 0, no regression).

RESULTS

Two patients had a pathologic complete response. Good response (Grade 3 + 4) was found in 57.7 percent of the resected specimens. Cyclooxygenase-2 was expressed in 80.8 percent of patients before chemoradiotherapy and in 100 percent after chemoradiotherapy. The rates of good response (Grade 3 + 4) were significantly associated with lack of cyclooxygenase-2 expression before chemoradiotherapy (P = 0.021). However, there was no correlation between p53 protein expression and tumor regression grading.

CONCLUSIONS

Patients with tumor lacking cyclooxygenase-2 expression before chemoradiotherapy are more likely to demonstrate good response to treatment. Cyclooxygenase-2 protein expression may be a marker for response to chemoradiotherapy in patients with rectal cancer.