Expression of PPARγ and PTEN in human colorectal cancer: An immunohistochemical study using tissue microarray methodology

Abstract

Abstract. Although aberrations of peroxisome proliferatoractivated receptor γ (PPARγ) and phosphatase and tensin homolog (PTEN) expression have been identified in several other cancer types, certain previous studies have revealed that PPARγ is abundant in normal and malignant tissue in the colon. The question of whether aberrant PTEN is involved in the initial stage or is a later event during colorectal carcinogenesis remains controversial. Relatively few studies have focused on the correlation of expression of PPARγ and PTEN in various tissues. In the present study, paraffin-embedded blocks from 139 patients with CRC, 18 adenomatous polyps and 50 paired paracancerous benign mucosas were selected and analysed in 4 tissue microarray (TMA) blocks comprising 104, 72, 130 and 54 cores, respectively. Expression of PPARγ and PTEN was examined using immunohistochemical staining on TMAs. There were no significant differences in the expression of PPARγ (P=0.055) and PTEN (P=0.100) between the colorectal cancers, adenomas and paracancerous mucosas. However, correlations of PPARγ expression with clinical stage (P=0.004) and PTEN expression with histological grade (P=0.006) and distant metastasis (P=0.015) were demonstrated in the CRC specimens. Although the differences in PPARγ and PTEN protein expression in human colorectal cancer may not be considered as early diagnostic markers, our results indicate that CRCs with a low expression or deletion of PTEN may progress towards invasion and even metastasis; thus, PTEN may have potential as a prognostic marker in human CRC.

PTEN expression profiles in colorectal adenocarcinoma and its precancerous lesions

“…They also reported, similarly to the present study, some well-defined differences in PTEN expression between normal colonic mucosa, adenomatous polyps and CRC. Such a relationship has been noted by other authors as well [21,22].…”

Dysregulation of MicroRNA-543 expression in colorectal cancer promotes tumor migration and invasion

“…Weak expression (cytoplasm and nuclear staining) of PTEN is associated with liver metastasis and poor patient survival in CRC . Similarly, PTEN expression is positively associated with histological grades and distant metastases in CRC . It is well know that PTEN protein plays an important role in cell growth, apoptosis, migration, invasion, and adhesion by negatively regulating several signaling pathways.…”

FOLFIRI and Cetuximab Every Second Week for First-Line Treatment of KRAS Wild-Type Metastatic Colorectal Cancer According to Phosphatase and Tensin Homolog Expression: A Phase II Study

“…9 In addition, other reports have indicated that the loss of PTEN might reflect tumor aggressiveness. 10,11 However, in a series of 173 patients receiving second-or greater line cetuximab treatment, PTEN status was reported to correlate only with overall survival (OS) but not with response or PFS. 12 These findings raise the question of whether the loss of PTEN expression might be a predictive marker of outcome after anti-EGFR treatment or a prognostic marker to identify patient outcomes, regardless of the treatment response.…”