Downregulation of human leukocyte antigen Class I expression: An independent prognostic factor in colorectal cancer

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 Conclusions:HLA Class I expression is an independent and sensitive clinical prognostic marker that might be used in CRC patients.