ABSTRACT
Background & objectives: Transforming growth factor-beta (TGF-ß) signalling pathway has been reported to be involved in metastasis and at the same time has been considered compellingly an important mediator of epithelial-to-mesenchymal transition (EMT). Besides, EMT process is maintained by zinc-finger E-box-binding homeobox 1 (ZEB1) gene which is induced by TGF-ß pathway. TGF-ß has been shown to be associated with elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) phenomenon, which is one of the prognostic biomarkers of colorectal cancer (CRC). This study was conducted to determine the link among ZEB1-induced TGF-ß, EMAST status and metastasis. Methods: The expression level of ZEB1 was evaluated using quantitative reverse transcription (qRT) real-time PCR in 122 formalin fixed paraffin-embedded tissues of CRC sample with known EMAST status and TGF-ß/Smad-dependent pathways. The association among ZEB1 expression, TGF-ß signalling pathway, EMAST status and metastatic behaviour was examined. Results: ZEB1 gene expression level was higher in tumour tissues as compared to normal samples (P<0.045). In addition, ZEB1 positive expression level was associated significantly with metastasis (P=0.05), EMAST+ status (P=0.052) and activated TGF-ß signalling pathway (P=0.002). Interpretation & conclusions: Our results validated significant association between activated TGF-ß signalling pathway and EMAST+ phenotype with higher expression of ZEB1 and higher level of metastasis.
Subject(s)
Colorectal Neoplasms , Zinc Finger E-box-Binding Homeobox 1 , Humans , Cell Line, Tumor , Colorectal Neoplasms/genetics , Colorectal Neoplasms/pathology , Epithelial-Mesenchymal Transition , Microsatellite Repeats/genetics , Neoplasm Metastasis , Transforming Growth Factor beta/metabolism , Zinc Finger E-box-Binding Homeobox 1/genetics , Zinc Finger E-box-Binding Homeobox 1/metabolismABSTRACT
AIM: In the present study, we evaluated the clinical prognostic value of human leukocyte antigen (HLA (Class I tumor cell expression in a series of colorectal cancer (CRC) patients and also explored the association of this expression profile with molecular features such as mutation status of KRAS and BRAF, microsatellite stability status, and clinicopathological characteristics of the patients. PATIENTS AND METHODS: Formalin-fixed paraffin-embedded tumor tissue of 258 CRC patient's sections were immunohistochemically stained and subsequently quantified for HLA Class I expression by the tumor cells. Determination of microsatellite instability (MSI) tumor status was ascertained using mononucleotide repeat microsatellite targets. KRAS and BRAF mutations were screened by polymerase chain reaction (PCR)-sequencing and cast-PCR, respectively. RESULTS: HLA Class I expression was normal in 91 cases (35.3%), downregulated in 119 (46.1%), and loss of expression in 48 (18.6%) cases. Forty (15.5%) tumors were MSI-H (MSH), 49 were MSI-L (19%), and 169 were microsatellite stable (MSS) (65.5%). Thirty-six (14%) and 15 (5.8%) of the patients exhibited mutation in the KRAS and BRAF, respectively. It was found that patients with downregulated expression of HLA Class I were associated with Stage II tumors (P < 0.001) and a MSS tumor status (P < 0.001), while patients with loss of expression were associated with MSH status (P < 0.001). Univariate and multivariate analyses revealed that HLA Class I downregulated expression was an independent prognostic parameter for shorter overall patient survival time (hazard ratio: 1.8, P = 0.003). CONCLUSIONS: HLA Class I expression is an independent and sensitive clinical prognostic marker that might be used in CRC patients.
