PP32 OVEREXPRESSION INDUCES NUCLEAR PLEOMORPHISM IN RAT PROSTATIC-CARCINOMA CELLS

Nuclear pleomorphism is an important diagnostic factor in tumour patho logy. Traditionally, nuclear pleomorphism is evaluated qualitatively o r semiquantitatively, often as a component of tumour grade; the molecu lar basis of nuclear pleomorphism, however, remains unclear. In this s tudy, we investigated the quantitative effects on nuclear morphology o f overexpressing pp32, a recently described nuclear phosphoprotein hig hly expressed in self-renewing and neoplastic cell populations, Assess ment of Feulgen-stained transfected and control lines of AT3.1, a rat prostatic carcinoma cell line, using a computerized Cellular Image Ana lysis System (ED CAS-200) showed that stable overexpression of human p p32 in AT3.1 cells is accompanied by marked increases in the coefficie nt of variation of nuclear shape, nuclear size and chromatin textures but not in DNA content. In contrast, stable transfection with control vector, with ms, or with bcl-2 failed to affect nuclear morphology, Ce ll cycle analysis further showed that pp32-related increases in variat ion of nuclear structure manifested principally in G(1). These studies suggest that pp32 plays a role either directly or indirectly in the c ontrol of nuclear shape of G(1) cells.