The ability to distinguish malignant from indolent
prostate cancer cells is critically important for identification of clinically significant
prostate cancer to minimize unnecessary overtreatment and sufferings endured by patients who have indolent
cancer. Recently, we discovered that loss of
giantin function as the primary Golgi targeting site for endoplasmic reticulum-derived transport vesicles in aggressive
prostate cancer cells caused a shift of the Golgi localization site of α-
mannosidase 1A to 130 KDa
Golgi matrix protein (GM130)-65 KDa Golgi reassembly-stacking
protein (GRASP65) site resulting in emergence of high
mannose N-
glycans on trans-Golgi
enzymes and
cell surface glycoproteins. To extend this observation, we isolated two cell clones (Clone 1 and Clone 2) from high passage LNCaP cells, which exhibited
androgen refractory property missing in low passage LNCaP cells, and characterized their malignant property. We have found that comparing to Clone 2, which does not have cell surface high
mannose N-
glycans and exhibits localization of α-
mannosidase 1A at
giantin site, Clone 1 displays cell surface high
mannose N-
glycans, exhibits localization of α-
mannosidase 1A at GM130-GRASP65 site, and shows a faster rate of closing the
wound in a wound healing assay. The results indicate that Golgi localization of α-
mannosidase 1A at GM130-GRASP65 site and appearance of cell surface high
mannose N-
glycans may serve as markers of malignant
prostate cancer cells.