The results provide direct genetic evidence that COX-2 plays a key role in tumorigenesis, and indicate that COX-2-selective inhibitors can be a new class of therapeutic agents for colorectal polyposis and cancer.
Overexpression of cyclooxygenase-2 (COX-2) has been implicated in carcinogenesis of human colorectal cancer which is one of the leading types of cancer in Western countries.
In the following article, the phenotypes of the two Ptgs (genes coding for COX-1 and COX-2) knockouts are summarized, and recent studies to investigate the effects of COX deficiency on cancer susceptibility, inflammatory response, gastric ulceration, and female reproductive processes are discussed.
Overexpression of COX-2 in cancer tissues compared with matched non-cancerous tissues was found in 70% of cases and was significantly associated with lymphatic involvement, lymph node metastasis and advanced tumor stage.
We investigated the expression of COX-2 and prostaglandin (PG) E((2)) production in two human skin epidermal cancer cell lines: cutaneous squamous cell carcinoma, HSC-5, and eccrine carcinoma, EcCa.
Both gastrin and CCK(B)-R mRNA were detected by RT-PCR in the cancer tissue and similarly COX-2 mRNA and protein were found in most of cancers and in the HP infected antral mucosa but not in HP eradicated patients in whom only cancer tissue but not gastric mucosa expressed COX-2.
These data suggest that COX-2 expression might regulate carcinogenesis of bile duct epithelial cells in inflammatory regions and tumor progression in this cancer.
Taken together, our results suggest that overexpression of mPGES in addition to COX-2 contributes to increased amounts of PGE(2) in colorectal adenomas and cancer.
Both gastrin and CCKB-R mRNA were detected in the cancer tissue and at the resection margin and similarly COX-2 mRNA was expressed in most cancers and resection margin but not in bronchial mucosa where only COX-1 was found.
We propose that pretreatment with selective Cox-2 inhibitors may be useful in the prevention of multidrug resistance in response to cancer chemotherapy and should be further evaluated.
Normal-appearing breast epithelia adjacent to cancer expressed COX-2 in 81% of cases and was generally focal and of similar or decreased intensity relative to adjacent neoplastic epithelia.
Gastrin and CCK(B)-R mRNA were detected in the cancer tissue and the resection margin and similarly COX-2 mRNA was expressed in most of cancers and their resection margin but not in intact colonic mucosa where only COX-1 was detected.
These data indicate that COX-2 is up-regulated in human thyroid cancer, but not in benign thyroid nodules, and suggest that COX-2 expression may serve as a marker of malignancy in thyroid nodules.
Collectively, these results suggest that overexpression of COX-2 is a frequent phenomenon in hypopharyngeal carcinoma and may play a role in tumorigenesis of this cancer.
Several studies indicate that phospholipase A(2) (PLA(2)) expression and/or activation account for the high levels of arachidonic acid (AA) detected in cancer and, together with the elevated expression of cyclooxygenase-2, lead to cell proliferation and tumor formation.