The role of the different epithelial compartments during degeneration and regeneration of the rat prostate is examined on basis of intermediate filament protein (IFP) expression pattern. With the monoclonal antibodies RCK 103 and RGE 53, directed against specific keratins, it was possible to differentiate between the basal (RCK 103+) and luminal (RGE 53+) cells of the prostatic epithelium. After testosterone deprivation, by orchiectomy, an extensive and rapid cell loss was observed which appeared to affect mainly the luminal cells. In the process of prostate regeneration, induced by testosterone administration, using silastic implants, the luminal compartment rapidly regained its normal thickness. A heterogeneous population of morphologically luminal cells was observed showing keratin expression patterns intermediate between basal and luminal cells. These findings support the idea of a relationship between basal and luminal cells as being members of the same lineage of differentiation.

Here we discuss the hypothesis that the RNA components of the Ro ribonucleoproteins (RNPs), the Y RNAs, can be processed into microRNAs (miRNAs). Although Ro RNPs, whose main protein components Ro60 and La are targeted by the immune system in several autoimmune diseases, were discovered many years ago, their function is still poorly understood. Indeed, recent data show that miRNA-sized small RNAs can be generated from Y RNAs. This hypothesis leads also to a model in which Ro60 acts as a modulator in the Y RNA-derived miRNA biogenesis pathway. The implications of these Y RNA-derived miRNAs, which may be specifically produced under pathological circumstances such as in autoimmunity or during viral infections, for the enigmatic function of Ro RNPs are discussed.

To evaluate if there is any consistent relationship between the expression of intermediate filament proteins (IFP), particularly keratins, and the degree of malignancy of prostatic cancer cells, a series of nine Dunning rat prostatic cancer sublines that span the entire spectrum of progression of prostatic cancer were studied immunocytochemically by the use of a variety of antibodies specific for keratins, vimentin, or desmin. For the keratin studies, monoclonal antibodies with either a general reactivity to several keratins or highly specific for either luminal or basal epithelial cells of the normal rat prostate were used. By use of an antibody specific for luminal cell keratin 18, the luminal tumor cells of the well-differentiated, slow-growing H and HI-S sublines were positively stained. In most of the sublines with a more advanced state of progression (i.e., the moderately differentiated, moderately fast growing HI-M; the poorly differentiated, faster growing HI-F; and the anaplastic, very fast growing AT-1, AT-2, and MAT-Lu tumors), however, no expression of keratin specific for luminal cells was detected. In addition, several of the most advanced sublines (i.e., AT-1, AT-2, and MAT-Lu) were negative using any of the keratin antibodies. In contrast, several of the other sublines with the most advanced degree of progression (i.e., the anaplastic, very fast growing MAT-LyLu tumor derived from the AT-1 subline; and the anaplastic, very fast growing AT-3 tumor, derived from the HI-F subline), however, were positively stained with the keratin antibody specific for the luminal cells. By use of the keratin antibody specific for the basal cells of the normal rat prostate, the basal tumor cells of the well-differentiated slow-growing H and HI-S tumor were positively stained. This positive staining for basal cell keratin was also found in the HI-M and HI-F tumors, while the AT-1, AT-2, MAT-Lu, MAT-LyLu, and AT-3 were negative with this antibody. Thus, a loss in staining for basal cell keratin was consistently associated with the most advanced state of tumor progression. Vimentin-positive staining was demonstrated either alone or with keratin-positive staining in part of the epithelial cancer cells of all the sublines. An increase in the positive staining for vimentin was consistently associated with a more advanced state of tumor progression. Desmin-positive staining was found only in smooth cells present within the various tumor sublines.(ABSTRACT TRUNCATED AT 400 WORDS)

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