A subset of prostate basal cells lacks the expression of corresponding phenotypic markers

Immunohistochemical staining for cytokeratin (CK) 34ssE12 has been routinely used to elucidate prostate basal cells for differentiation between non-invasive and invasive lesions. Our previous studies, however, revealed that some morphologically distinct basal cells observed on H&E-stained sections completely lacked CK34ssE12 expression. Our current study attempted to assess whether these basal cells would also lack the expression of other phenotypic markers, and whether basal cell alterations would affect the proliferation status of the associated tumor cells. Consecutive sections from prostate tumors with large basal cell clusters that were morphologically distinct in H&E sections but were completely negative for CK 34ssE12 were morphologically and immunohistochemically assessed with a panel of basal cell phenotypic and other markers. In addition to CK 34ssE12, these basal cells also completely lacked the expression of other phenotypic markers, including CK5, CK14, p63, and maspin, in contrast to adjacent basal cells, which were strongly positive for these markers. Tumors surrounded by basal cell layers that lack the expression of basal cell phenotypic markers showed a significantly higher rate of cell proliferation and mast cell infiltration than their counterparts. These findings suggest that basal cells might be targets of a variety of pathological alterations, which could significantly impact biological presentations of associated tumor cells.