Cyclooxygenase-2 inhibition: effects on tumour growth, cell cycling and lymphangiogenesis in a xenograft model of breast cancer

Abstract

Cyclooxygenase-2 (COX-2) is associated with poor-prognosis breast cancer. We used a nude mouse xenograft model to determine the effects of COX-2 inhibition in breast cancer. Oestrogen receptor (ER)-positive MCF7/HER2-18 and ER-negative MDAMB231 breast cancer cell lines were injected into nude mice and allowed to form tumours. Mice then received either chow containing Celecoxib (a COX-2 inhibitor) or control and tumour growth measured. Tumour proliferation, apoptosis, COX-2, lymphangiogenesis and angiogenesis were assessed by immunohistochemistry (IHC), Western blotting or Q-PCR. Celecoxib inhibited median tumour growth in MCF7/HER2-18 (58.7%, P ¼ 0.029) and MDAMB231 (46.3%, P ¼ 0.0002) cell lines compared to control. Cyclooxygenase-2 expression decreased following Celecoxib treatment (MCF7/HER2-18 median control 65.3% vs treated 22.5%, P ¼ 0.0001). Celecoxib increased apoptosis in MCF7/HER2-18 tumours (TUNEL 0.52% control vs 0.73% treated, P ¼ 0.0004) via inactivation of AKT (median pAKT ser473 57.3% control vs 35.5% treated, P ¼ 0.0001 -confirmed at Western blotting). Q-PCR demonstrated decreased podoplanin RNA (lymphangiogenesis marker) in the MCF7/HER2-18 -median 2.9 copies treated vs 66.6 control (P ¼ 0.05) and MDAMB231-treated groups -median 160.7 copies vs 0.05 control copies (P ¼ 0.015), confirmed at IHC. Cyclooxygenase-2 is associated with high levels of activated AKT ser473 and lymphangiogenesis in breast cancer. Cyclooxygenase-2 inhibition decreases tumour growth, and may potentially decrease recurrence, by inactivating AKT and decreasing lymphangiogenesis.

Targeting COX-2 and EP4 to control tumor growth, angiogenesis, lymphangiogenesis and metastasis to the lungs and lymph nodes in a breast cancer model

“…36 Additionally, we show that system is also exquisitely suited to measuring tumor-associated lymphangiogenesis and lymphatic metastasis to local and distant nodes. Although human cancer cell xenografts in immunodeficient mice have been utilized to study tumor-associated lymphangiogenesis and/or lymphatic metastasis, 41,42 to our knowledge, ours is the first syngeneic breast cancer model in immune competent mice showing rapid and spontaneous metastasis of the primary tumor to regional and distant lymph nodes, mimicking aggressive breast cancer in the human. Using this model, this study demonstrated that an EP4 antagonist ONO-AE3-208, but not EP1 antagonist ONO-8713 was highly and equally effective as a COX-2 inhibitor celecoxib in inhibiting primary tumor growth, tumor-associated angiogenesis and lymphangiogenesis, and metastasis to the lymph nodes and the lungs.…”

Preparation of polylactide-co-glycolide nanoparticles incorporating celecoxib and their antitumor activity against brain tumor cells

“…In other reports, expression of COX-2 protein was also not specifically inhibited by celecoxib. 41,42 Barnes et al 41 reported that COX-2 protein expression was decreased by treatment with celecoxib. However, it seems that the decreased COX-2 expression and antiproliferative effect of celecoxib treatment is more related to apoptosis of tumor cells rather than specific inhibition of COX-2 expression by celecoxib.…”

“…However, it seems that the decreased COX-2 expression and antiproliferative effect of celecoxib treatment is more related to apoptosis of tumor cells rather than specific inhibition of COX-2 expression by celecoxib. 41,42 Celecoxib is known to inhibit expression of non-COX-2 targets, such as carbonic anhydrases, 3-phosphoinositide-dependent protein kinase-1, sarcoplasmic/endoplasmic reticulum, and calcium ATPase in tumor cells. Furthermore, celecoxib is known to increase apoptosis of tumor cells via inactivation of Akt, which is a member of the serine/threonine kinase family.…”

A Randomized, Placebo-Controlled, Phase II, Presurgical Biomarker Trial of Celecoxib Versus Exemestane in Postmenopausal Breast Cancer Patients

“…COX-2 is widely expressed in both invasive and preinvasive breast lesions (11) and PGE2 biosynthesis is considered one check point in the mammary carcinogenesis pathway. Moreover, increased PGE2 levels stimulate aromatase transcription (12). Therefore, NSAIDs and selective anti-COX-2 inhibitors may reduce breast cancer risk through the downregulation of aromatase expression (13).…”