Expression of Human Placenta-specific 1 (PLAC1) in CHO-K1 Cells

Background: placenta-specific 1 (plac1), as a new cancer/testis antigen (cta), is frequently expressed in a variety of cancers and localized to cytoplasm and plasma membrane. surface expression of cancer target antigens is of great importance that enables antibody-mediated cancer immunotherapy. the aim of the current study was to express the intact human plac1 protein on plasma membrane of a eukaryotic cell as a model for future anti-plac1-based cancer immunotherapy. methods: in the first approach, entire human plac1 gene including its own signal peptide (sp) was cloned into pires2-egfp and lego-ig2 vectors and expressed in cho-k1 cells. in the second approach, cytosolic and signal-anchor (sa) sequence of transferrin receptor protein 1 (tfr1) were fused to extracellular portion of plac1 and expressed as above. expression of plac1 was then assessed using reverse transcription polymerase chain reaction (rt-pcr), western blot (wb), immunocytochemistry (icc), immunofluorescence (if) and flow cytometry (fc). results: the first approach resulted in the expression of plac1 in submembranous but not in the surface of transfected cho-k1 cells. using the chimeric human plac1 construct, the same intracellular expression pattern was observed. conclusion: these results indicated that there are some yet unknown plac1 localization signals employed by cancer cells for surface expression of plac1.