Genome-wide gene expression profile analyses identify CTTN as a potential prognostic marker in esophageal cancer

Abstract

Aim: Esophageal squamous cell carcinoma (ESCC) is one of the most common fatal malignances of the digestive tract. Its prognosis is poor mainly due to the lack of reliable markers for early detection and prognostic prediction. Here we aim to identify the molecules involved in ESCC carcinogenesis and those as potential markers for prognosis and as new molecular therapeutic targets.

Methods: We performed genome-wide gene expression profile analyses of 10 primary ESCCs and their adjacent normal tissues by cDNA microarrays representing 47,000 transcripts and variants. Candidate genes were then validated by semi quantitative reverse transcription-PCR (RT-PCR), tissue microarrays (TMAs) and immunohistochemistry (IHC) staining.

Results: Using an arbitrary cutoff line of signal log ratio of ≥1.5 or ≤-1.5, we observed 549 up-regulated genes and 766 down-regulated genes in ESCCs compared with normal esophageal tissues. The functions of 302 differentially expressed genes were associated with cell metabolism, cell adhesion and immune response. Several candidate deregulated genes including four overexpressed (CTTN, DMRT2, MCM10 and SCYA26) and two underexpressed (HMGCS2 and SORBS2) were subsequently verified, which can be served as biomarkers for ESCC. Moreover, overexpression of cortactin (CTTN) was observed in 126/198 (63.6%) of ESCC cases and was significantly associated with lymph node metastasis (P = 0.000), pathologic stage (P = 0.000) and poor survival (P<0.001) of ESCC patients. Furthermore, a significant correlation between CTTN overexpression and shorter disease-specific survival rate was found in different subgroups of ESCC patient stratified by the pathologic stage (P<0.05).

Conclusion: Our data provide valuable information for establishing molecules as candidates for prognostic and/or as therapeutic targets.

Figure 1. The differential expression of CTNN in ESCC.

(A) Semiquantitative reverse transcription-PCR (RT-PCR) was applied to compare expression status of CTTN, DMRT2, MCM10, SCYA26, HMGCS2 and SORBS2 between 8 pairs of primary ESCC tumor samples and matched normal esophageal epithelia. GAPDH was used as an internal control. (B) Representative of CTNN expression in a pair of ESCC (right) and adjacent normal tissue (left) detected by immunostaining with anti-CTNN antibody (brown). The slide was counterstained with hematoxylin (Original magnification: upper ×100, bottom ×200).

Figure 2. Kaplan-Meier plots for the Disease-specific survival rate of ESCC patients.

(A) Kaplan-Meier plots for the Disease-specific survival (DSS) rate of ESCC patients with (n = 126, green line) or without (n = 72, blue line) CTNN overexpression. (B) Kaplan-Meier plots for the DSS rate of ESCC patients with pathologic stage I+IIA (n = 113, blue line) or IIB+III (n = 85, green line).

Figure 3. Kaplan-Meier plots for the DSS rate in ESCC patients subgrouped into pathologic stage I-IIA (A) and pathologic stage IIB-III (B) as differentiated by with (+) or without (−)-CTTN overexpression.