301

ANXA1

ANX1|LPC1;annexin A1;ANXA1;annexin A1

annexin I (lipocortin I)|annexin-1|calpactin II|calpactin-2|chromobindin-9|lipocortin I|p35|phospholipase A2 inhibitory protein

9q12-q21.2|9q21.13

protein-coding

Count: 1; Generif

Stress proteins protect cells against the effects of heat stress, such as cell death and DNA damage. We wished to determine if Annexin-1 (ANXA1) could mediate heat-induced growth arrest and DNA damage in MCF7 breast cancer cells. Heat induced a significant growth arrest at 4h-24h. Growth arrest and heat-induced DNA damage were significantly inhibited in MCF7 cells over-expressing ANXA1. These effects were associated with enhanced ERK activation and reduction in JNK phosphorylation. This study demonstrates that ANXA1, which we recently reported as a possible tumor suppressor gene, can protect cells from heat-induced growth arrest and DNA damage.CI - Copyright (c) 2010 Elsevier Ireland Ltd. All rights reserved.

BACKGROUND: Although reduced expression levels of annexin I (ANX I) protein is a common finding in all stages of prostate cancer a causative relationship between ANX I dysregulation and prostate cancer development has yet to be established. METHODS: Annexin I expression was restored in LNCaP and MDA PCa 2b that normally express low or undetectable levels of ANX I protein. The impact of restoring ANX I expression on cell viability, colony formation in soft agar, apoptosis, and extracellular signal-regulated kinases (ERK), p38, c-Jun N-terminal kinases (JNK) activation was examined. RESULTS: Restoring ANX I expression reduced cell viability, colony formation, in addition to inducing apoptosis. The proliferative response of epidermal growth factor was blocked by restoring ANX I expression. Furthermore, increasing basal and induced levels of phosphorylated p38 and JNK were observed in prostate cancer cells following restoration of ANX I expression. CONCLUSIONS: Annexin I may have tumor suppressor functions in prostate cancer. The pro-apoptotic effect of ANX I involves the activation of p38 and JNK, which appears to shift the balance of signal transduction away from proliferation and toward apoptosis.

PURPOSE: The purpose is to characterize alterations of the annexin I gene, its mRNA, and protein expression in esophageal squamous cell carcinoma. EXPERIMENTAL DESIGN: Fifty-six cases of esophageal squamous cell carcinoma were analyzed using four microsatellite markers flanking the annexin I gene (9q11-q21) to identify loss of heterozygosity. In addition, we performed (a) single-strand conformation polymorphism and DNA sequencing along the entire promoter sequence and coding region to identify mutations, (b) real-time quantitative reverse transcription-PCR of RNA from frozen esophageal squamous cell carcinoma tissue (n = 37) and in situ hybridization (n = 5) on selected cases to assess mRNA expression, and (c) immunohistochemistry (n = 44) to evaluate protein expression. The prevalence of the allelic variants identified in the first 56 patients was refined in 80 additional esophageal squamous cell carcinoma patients and 232 healthy individuals. RESULTS: Forty-six of 56 (82%) esophageal squamous cell carcinoma patients showed loss of an allele at one or more of the four microsatellite markers; however, only one (silent) mutation was seen. Two intragenic variants were identified with high frequency of allelic loss (A58G, 64%; L109L, 69%). Thirty of 37 (81%) esophageal squamous cell carcinoma patients showed reduced annexin I mRNA expression, which was confirmed by in situ hybridization, whereas annexin I protein expression was reduced in 79% of poorly differentiated tumor cell foci but in only 5% of well-differentiated tumor foci, although allelic loss on chromosome 9 was found in both tumor grades. CONCLUSIONS: Allelic loss of annexin I occurs frequently, whereas somatic mutations are rare, suggesting that annexin I is not inactivated in esophageal squamous cell carcinoma via a two-hit mechanism. A decrease in annexin I protein expression was confirmed, consistent with a quantitative decrease in mRNA expression, and appeared to be related to tumor cell differentiation. We conclude that annexin I is not the tumor suppressor gene corresponding to the high levels of loss of heterozygosity observed on chromosome 9 in esophageal squamous cell carcinoma; however, dysregulation of mRNA and protein levels is associated with this tumor type.