Characterization of the human Ly‐6 antigens, the newly annotated member Ly‐6K included, as molecular markers for head‐and‐neck squamous cell carcinoma

Abstract

The E48 antigen is a successfully explored molecular marker for the diagnosis and therapy of HNSCC. The applicability of E48 as an HNSCC-associated antigen, however, is restricted due to its heterogeneous expression in 30% of tumors; and identification of additional target antigens is therefore desired. E48 belongs to the Ly-6 antigen family, comprising a group of highly homologous, low m.w., GPIanchored surface proteins, of which some show tissue-restricted expression patterns. To identify novel human HNSCC-associated Ly-6 members with squamous cell-associated expression patterns, we performed comprehensive gene-screening consisting of BLAST searches within GenBank databases, followed by expression analysis. Using this approach, the Ly-6K gene could be annotated as a novel member of the human Ly-6 family. Expression of the human Ly-6 genes E48, Ly-6K, PSCA, GML, RIG-E, G6C and Ly-6H was prescreened by qualitative RT-PCR and subsequently analyzed by quantitative RT-PCR in normal keratinocytes, HNSCC cell lines, normal mucosa, HNSCC tumors as well as normal peripheral blood and bone marrow cells. PSCA was highly expressed in normal mucosa, but 100-fold decreased expression was seen in HNSCC. For Ly-6H, GML and G6C, no or very low expression was observed in keratinocytes and HNSCC. Expression of RIG-E was high in normal and malignant squamous cells and in peripheral blood and bone marrow cells, thus limiting its applicability as an HNSCC-associated marker. In contrast, besides the E48 gene, the Ly-6K gene also appeared to be selectively expressed in HNSCC and normal squamous cells. Moreover, expression of Ly-6K was shown in HNSCC cell lines, in which no E48 expression could be detected. These data justify further evaluation of Ly-6K as potential target antigen for the diagnosis and therapy of HNSCC.

The Regulatory Mechanism of the LY6K Gene Expression in Human Breast Cancer Cells

“…LY6K has been reported as a testicular cancer antigen that is not only a target antigen for head-and-neck squamous cell carcinoma but also a diagnostic marker for breast cancer and a serologic biomarker and therapeutic target for lung and esophageal carcinomas (7)(8)(9). Activating LY6K results in an increase in cell invasive motility and metastasis, whereas a low level of LY6K reduces cell mobility in breast cancer cells (12).…”

“…The LY6K was first identified as a molecular marker for head-and-neck squamous cell carcinoma (7). Previous studies have shown that cancer-testis antigen LY6K could be a diagnostic biomarker and a therapeutic target for breast cancer, nonsmall cell lung carcinoma, bladder cancer, and esophageal squamous cell carcinoma (8 -11).…”

High incidence of EMMPRIN expression in human tumors

“…HNSCC cell lines (except JCRB 1027 SAT) were kindly provided by Dr. R. H. Brakenhoff (Department of Otolaryngology/Head-Neck Surgery, VUMC Amsterdam, the Netherlands). [19][20][21] The HNSCC cell line JCRB 1027 SAT was obtained from the Japan Health Science Foundation, Health Science Research Resources Bank. Cells were grown as monolayers (except DU4475 cells) in DMEM medium (Invitrogen, Karlsruhe, Germany) supplemented with 10% fetal calf serum (PAA Labora-tories GmbH, Pasching, Austria) and 2 mM L-glutamine (Invitrogen) at 37°C in a humidified 10% CO 2 atmosphere.…”

Phase I clinical trial of vaccination with LY6K-derived peptide in patients with advanced gastric cancer

“…LY6K overexpression has been confirmed in several malignancies including head and neck squamous cell carcinomas as well as breast, lung, bladder, and esophageal cancers [12,13,[15][16][17][18][19]. LY6K overexpression is associated with a poorer prognosis in patients with non-small cell lung carcinomas as well as those with esophageal squamous cell carcinomas [12].…”

“…To determine the status of LY6K protein in clinical gastric cancer samples embedded in paraffin blocks, we performed immunohistochemistry as described previously [12,15,16]. Briefly, rabbit polyclonal antihuman LY6K antibodies (TM38) were applied to the sections after blocking endogenous peroxidases and proteins.…”