Increased expression of tumor necrosis factor-α is associated with advanced colorectal cancer stages

Abstract

Aim: To detect the expression of tumor necrosis factor-α (TNF-α) in colorectal cancer (CRC) cells among Saudi patients, and correlate its expression with clinical stages of cancer.

Methods: Archival tissue specimens were collected from 30 patients with CRC who had undergone surgical intervention at King Khalid University Hospital. Patient demographic information, including age and gender, tumor sites, and histological type of CRC, was recorded. To measure TNF-α mRNA expression in CRC, total RNA was extracted from tumor formalin-fixed, paraffin-embedded, and adjacent normal tissues. Reverse transcription and reverse transcription polymerase chain reaction were performed. Colorectal tissue microarrays were constructed to investigate the protein expression of TNF-α by immunohistochemistry.

Results: The relative expression of TNF-α mRNA in colorectal cancer was significantly higher than that seen in adjacent normal colorectal tissue. High TNF-α gene expression was associated with Stage III and IV neoplasms when compared with earlier tumor stages (P = 0.004). Eighty-three percent of patients (25/30) showed strong TNF-α positive staining, while only 10% (n = 3/30) of patients showed weak staining, and 7% (n = 2/30) were negative. We showed the presence of elevated TNF-α gene expression in cancer cells, which strongly correlated with advanced stages of tumor.

Conclusion: High levels of TNF-α expression could be an independent diagnostic indicator of colorectal cancer, and targeting TNF-α might be a promising prognostic tool by assessment of the clinical stages of CRC.

Keywords: Colorectal cancer; Immunohistochemistry; Real time polymerase chain reaction; Tumor necrosis factor-α; mRNA.

Figure 1

Image analysis of immunohistochemistry. Representative images showing how image analysis was performed on cores immunostained for tumor necrosis factor-α. A: A square field is selected; B: A color markup overlay produced by the color deconvolution algorithm reflecting the intensity ranges of the Diaminobenzedine (brown) stain; blue, negative; yellow, weak positive; orange, medium positive; red, strong positive. Scale bar = 100 mm.

Figure 2

Tumor necrosis factor-α gene expression in colorectal cancer by real time polymerase chain reaction. Tumor necrosis factor-α (TNF-α) gene expression shows a statistically significant difference expression between advanced and early stages of colorectal cancer (P = 0.004).

Figure 3

Semi-quantitative evaluation of tumor necrosis factor-α protein expression. A: Percentage of samples showing no staining, weak or strong immunohistochemistry staining; B, D and E: Representative microscopic images of tumor necrosis factor-α (TNF-α) immunohistochemical expression of by tumor cells (cytoplasmic staining pattern, is pointed by arrow; B: No staining in normal colon mucosa; C: Weak; D-E: Strong cytoplasmic staining. TNF-α expression is increased in basal tumor cells. In advanced stage tumor TNF-α expression was strong D-E (magnification, × 400).