Three isoforms of annexin I are preferentially expressed in normal esophageal epithelia but down-regulated in esophageal squamous cell carcinomas

Abstract

The development and progression of human cancer are believed to be due to the alterations of multiple genes or/ and their protein products. For identifying the proteins associated with esophageal cancer, we analysed the protein profiles of 24 pairs of esophageal squamous cell carcinomas/matched adjacent normal epithelia. Microdissection of routinely unstained frozen sections was performed to purify cancerous and epithelial cells. The protein expression profiles were obtained by twodimensional electrophoresis. Selected proteins dysregulated in tumors were identified by MALDI-TOF-MS. Three isoforms of annexin I were detected in normal esophageal mucosa and down-regulated in esophageal squamous cell carcinomas. RT -PCR analysis showed annexin I mRNA levels were significantly reduced in 17 out of 24 carcinomas. Immunohistochemistry demonstrated that annexin I appeared strong positive in all normal epithelia layers except basal cells. In cancer tissues, decreased expression of annexin I was observed in 12 out of 16 well differentiated tumors, 16 out of 17 moderately differentiated tumors, and 3 out of 3 poorly differentiated tumors as compared with the corresponding normal esophageal epithelia. There was a significant correlation between annexin I expression and the status of tumor differentiation. Well differentiated tumors presented stronger immunohistochemical reaction than moderately and poorly differentiated tumors. These data suggested that there existed three different isoforms of annexin I in normal esophageal epithelia, which may be the results of post-translational modification. Downexpression of three annexin I isoforms was a frequent event in esophageal carcinogenesis.

MicroRNA-196a targets annexin A1: a microRNA-mediated mechanism of annexin A1 downregulation in cancers

“…Western blotting and immunohistochemical analysis showed a drastic decrease or complete loss of ANXA1 levels in esophageal tumors and high-grade dysplasia when compared to the paired normal epithelium, implying that ANXA1 plays a functional role in maintaining the normal status of esophageal epithelium (Paweletz et al, 2000). A comparative protein profiling study also identified lower ANXA1 protein levels in esophageal carcinomas than in the paired normal epithelia (Xia et al, 2002). In their study, ANXA1 levels were found to be suppressed in 75% of welldifferentiated, 94% of moderately differentiated and 100% of the poorly differentiated tumors analysed, thus correlating with the extent of tumor differentiation.…”

“…In esophageal cancers, several published reports confirm that the loss of ANXA1 is an early event in tumorigenesis (Paweletz et al, 2000;Xia et al, 2002;Hu et al, 2004). Western blotting and immunohistochemical analysis showed a drastic decrease or complete loss of ANXA1 levels in esophageal tumors and high-grade dysplasia when compared to the paired normal epithelium, implying that ANXA1 plays a functional role in maintaining the normal status of esophageal epithelium (Paweletz et al, 2000).…”

“…In light of the report that ANXA1 mRNA levels progressively decrease from normal esophageal epithelium to Barrett's esophagus (BE) and from BE to adenocarcinoma (Kimchi et al, 2005), it would be interesting to determine if miR-196a level can be used as early marker of esophageal cancer. Though our study predominantly focused on esophageal adenocarcinomas, previous studies have reported an association between ANXA1 loss and tumorigenesis of squamous cell carcinoma of the esophagus (Paweletz et al, 2000;Xia et al, 2002;Hu et al, 2004). It is conceivable that miR-196a plays a similar role in this other major subtype of esophageal cancer as seen in adenocarcinoma subtype.…”

“…The inverse correlation was statistically significant (Pearson's correlation À0.64, P ¼ 0.047). Loss of ANXA1 expression is a frequent molecular change observed in esophageal cancer (Paweletz et al, 2000;Xia et al, 2002;Hu et al, 2004). To further confirm this observation and to investigate the possible role of miR-196a in this molecular change, the levels of ANXA1 mRNA and miR-196a were analysed in paired normal (esophageal or gastric) and tumor tissues from 10 patients.…”

“…Suppression or loss of ANXA1 expression reported in different cancers such as prostate (Kang et al, 2002), breast (Shen et al, 2006), esophageal cancers (Paweletz et al, 2000;Xia et al, 2002;Hu et al, 2004) and B-cell non-Hodgkin's lymphoma (Vishwanatha et al, 2004) attributes tumor suppressive function to ANXA1 in these cancers. Furthermore, ANXA1 overexpression promoted caspase-mediated apoptosis in bronchoalveolar cells (Debret et al, 2003) and macrophages (Solito et al, 2001) and facilitated H 2 O 2 -induced apoptosis in thymocytes (Sakamoto et al, 1996).…”