Gli1 Expression with Survival in Esophageal Adenocarcinoma

Short Communication

Austin J Cancer Clin Res 2015;2(2): 1031.

Gli1 Expression with Survival in Esophageal Adenocarcinoma

Okereke IC1*, Fan QL2, Pulikal A2, Kohtz P2 and Xie J2

1Division of Thoracic Surgery, Department of Surgery, Warren Alpert Medical School of Brown University, USA

2Departments of Pediatrics, Biochemistry and Molecular Biology and Surgery, Indiana University School of Medicine, USA

*Corresponding author: Ikenna Okereke, Division of Thoracic Surgery, Department of Surgery, Warren Alpert Medical School of Brown University, 2 Dudley St., Suite 470, Providence, RI 02903, USA.

Received: February 16, 2015; Accepted: March 13, 2015; Published: March 26, 2015


Esophageal adenocarcinoma (EAC) is the fastest growing cancer over the last decade in the US, but the exact mechanisms responsible for EAC remain elusive. Identification of specific biomarkers for EAC has significant impacts on early detection of EAC and potential novel cancer therapeutics. The sonic hedgehog (Hh) signaling pathway is known to be activated in esophageal squamous cell carcinomas but its specific role in EAC remains unknown. Our goal was to determine the association between Hh signaling activation and outcomes in patients with EAC.

A total of 761 patients underwent esophagectomy at a tertiary care institution from 1993 to 2011. Of this group, 28 patients underwent esophagectomy alone for EAC, without neoadjuvant chemoradiation treatment. Portions of their tumor were freshly frozen and stored for later use. Expression of Hh target genes or ligands was determined in each tumor using real-time polymerase chain reaction (Gli1, Gli2, Shh and Ihh). Demographics, pathologic data and survival were recorded.

Mean patient age was 66. There were no perioperative mortalities. Expression of Gli1 was significantly related to poor overall survival (p = 0.048) but was not related to age (p = 0.53) or gender (p = 0.19). Of all the genes analyzed, expression of Gli1 is significantly correlated to poor survival. Based on our data, we propose to perform novel clinical trials to treat patients with activated Hh signaling in EAC.

Keywords: Esophageal cancer; Hedgehog; Biomarkers; Tumorigenesis


Esophageal cancer is the most rapidly growing solid organ malignancy, while the incidence of many other cancer types have had a diminishing prevalence overall. Almost 18,000 people each year in the United States are affected by esophageal cancer [1]. Due to delayed diagnosis and usual advanced stage at presentation, the prognosis of EAC is generally poor. Adenocarcinoma of the esophagus predominates in the United States, whereas squamous cell cancer is more prevalent in the eastern hemisphere [2].

Current treatments of esophageal cancer are dependent upon the stage at diagnosis. Early stage disease is generally treated with surgical resection alone. For locally advanced disease, the treatment option is generally a combination of chemotherapy, radiation treatment and surgery [3]. Stage IV esophageal cancer, on the other hand, is usually treated with chemotherapy.

Initially identified as an important development signaling pathway, activation of Hh signaling has been reported in many solid organ tumors [4,5]. Hh ligands bind to the “patched” receptor, which triggers a signaling cascade leading to expression of Hh targets [6]. Specifically, two of these targets, glioma-associated oncogene 1 and glioma-associated oncogene 2 (Gli1 and Gli2), have been implicated in development of multiple cancers when overexpressed, including esophageal cancer, basal cell cancer, pancreatic cancer [7-9]. Overexpression of Hh targets has been associated with the development of esophageal squamous cell cancer [10]. Furthermore, high levels of Gli1 have been correlated with poor survival in esophageal squamous cell cancer [11]. It remains unclear the exact role of Hh signaling in esophageal adenocarcinoma. In this study, our goal was to examine the association of hedgehog signaling gene expression and outcome in esophageal adenocarcinoma.

Material and Methods

Tumor specimens

From 1993 through 2011, 761 patients underwent esophagectomy at Indiana University School of Medicine. After institutional review board approval, twenty-eight of these patients who underwent esophagectomy alone for esophageal adenocarcinoma had portions of their primary tumor freshly frozen to -80 degrees Celsius and stored for use. None of these patients had chemoradiation treatment prior to surgical resection. Pathologic evaluation of histology and stage was determined by an expert pathologist in all cases. Demographic variables, pathologic results and survival data were analyzed retrospectively. Statistical analysis of survival was performed using Kaplan-Meier, logistic regression, and Cox proportional analyses. Ap value of 0.05 or less was regarded as statistically significant.

Real-time PCR analyses

To measure the expression of Gli1 and Gli2, RNA was extracted from each specimen and reverse-transcribed to cDNA. Thereafter, real-time PCR was performed using tagman primers/probes to analyze the relative expression of Gli1, Gli2, Shh and Ihh compared to GAPDH expression. Several specimens had matched esophageal tissue surrounding the tumor, and were included in the analysis. Expression levels of these genes were then correlated to pathologic and survival data.


Analyses of patient information

A list of patient demographics is shown in Table 1. Eighty-six percent of patients (24/28) were male. Median age was 67 (43-83) yrs. No patient underwent neoadjuvant chemoradiation treatment. Patients who had a T stage of 3 or greater or nodal metastases received adjuvant chemoradiation treatment. In total, fifty-seven percent of patients (16/28) received adjuvant chemoradiation treatment. Median follow-up was 21.6 months. There were no perioperative mortalities.