Cyclooxygenase-2 and the inflammogenesis of breast cancer

Abstract

Cohesive scientific evidence from molecular, animal, and human investigations supports the hypothesis that constitutive overexpression of cyclooxygenase-2 (COX-2) is a ubiquitous driver of mammary carcinogenesis, and reciprocally, that COX-2 blockade has strong potential for breast cancer prevention and therapy. Key findings include the following: (1) COX-2 is constitutively expressed throughout breast cancer development and expression intensifies with stage at detection, cancer progression and metastasis; (2) essential features of mammary carcinogenesis (mutagenesis, mitogenesis, angiogenesis, reduced apoptosis, metastasis and immunosuppression) are linked to COX-2-driven prostaglandin E2 (PGE-2) biosynthesis; (3) upregulation of COX-2 and PGE-2 expression induces transcription of CYP-19 and aromatase-catalyzed estrogen biosynthesis which stimulates unbridled mitogenesis; (4) extrahepatic CYP-1B1 in mammary adipose tissue converts paracrine estrogen to carcinogenic quinones with mutagenic impact; and (5) agents that inhibit COX-2 reduce the risk of breast cancer in women without disease and reduce recurrence risk and mortality in women with breast cancer. Recent sharp increases in global breast cancer incidence and mortality are likely driven by chronic inflammation of mammary adipose and upregulation of COX-2 associated with the obesity pandemic. The totality of evidence clearly supports the supposition that mammary carcinogenesis often evolves as a progressive series of highly specific cellular and molecular changes in response to induction of constitutive overexpression of COX-2 and the prostaglandin cascade in the "inflammogenesis of breast cancer". Key words: Breast Cancer; Cyclooxygenase-2; Nonsteroidal anti-inflammatory drugs; Inflammogenesis; Estrogen; Aromatase Core tip: Mammary carcinogenesis often evolves as a series of highly specific cellular and molecular changes in response to induction of constitutive over-expression of cyclooxygenase-2 (COX-2) and the prostaglandin cascade; reciprocally, agents that block COX-2 have significant value in the chemoprevention and therapy of breast cancer.Harris RE, Casto BC, Harris ZM. Cyclooxygenase-2 and the inflammogenesis of breast cancer. World J Clin Oncol 2014; 5(4): 677-692 Available from: URL: http://www.wjgnet.com/2218-4333/full/v5/ i4/677.htm DOI: http://dx.doi.org/10.5306/wjco.v5.i4.677 INTRODUCTIONMore than a century ago, Virchow et al [1,2] chronic inflammation leads to cancer development by increasing cellular proliferation [3] . Various models of carcinogenesis have been proposed involving inflammatory stimuli and mediators of wound healing [4][5][6] . The recent discovery of the inducible cyclooxygenase-2 (COX-2) gene has rekindled interest in the causal link between inflammation and cancer, and various models of carcinogenesis have been proposed involving inflammatory stimuli and COX-2 expression [7][8][9][10] . The current review synthesizes and interprets the accumulating body of evidence supporting COX-2 driven inflammogenesis as a ge...

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