Missing expression of pRb2/p130 in human retinoblastomas is associated with reduced apoptosis and lesser differentiation.

Purpose: Although the retinoblastoma gene (RB/p105) has been intensely investigated as a prototype suppressor gene in humans, mutational data on the Rb family member pRb2/p130 (p130) has only recently been reported. A protective role against apoptosis has been suggested for pRb/p105, both in vitro and in vivo. However, only limited information is available on the role of pRb2/p130 in controlling apoptosis.

Expression of the ALK protein by anaplastic large-cell lymphomas correlates with high proliferative activity.

A variable fraction of anaplastic large-cell lymphomas (ALCLs) exhibits a t(2;5)(p23;q35) translocation that results in expression of the chimeric hyperphosphorylated protein NPM-ALK (p80). Tumor cells expressing NPM-ALK exhibit markedly enhanced proliferative activity, but comparative cellular kinetic studies on ALK(+) (ALK lymphomas) and ALK(-) lymphomas are lacking. The present study showed that ALK(+) lymphomas, detected with the monoclonal antibody ALKc (n = 17), had significantly higher average values for the proliferation-associated parameters mitotic index, ana/telophase index, growth index (x x mitotic index - apoptotic index, assuming x = 3), percentages of Ki-67(+) cells and fraction of cells expressing cyclin A or B or the cell cycle-regulatory protein p34(cdc2) than did ALK(-) ALCLs (n = 15).

Immunogold visualization of actin near the coated pits at the apical surface of human mammary epithelial cells.

This ultrastructural study of both the normal human breast tissue and differentiated mammary carcinoma (NOS) epithelial cells has revealed pictures demonstrating luminal receptor-mediated endocytosis. By application of immunogold anti-actin labeling, actin surrounding the fusion ring of coated pits was visualized. However, the coated membrane was not actin labeled.

Expression of p34(cdc2) and cyclins A and B compared to other proliferative features of non-Hodgkin's lymphomas: a multivariate cluster analysis.

In view of recent knowledge on proteins regulating the cell cycle, we re-evaluated proliferative features of 98 diffusely growing non-Hodgkin's lymphomas. The combined use of 5 proliferation-associated variables (mitotic indices and percentages of Ki-67(+), p34(cdc2+), cyclin A(+) and cyclin B(+) cells) and their entry into a multivariate cluster analysis separated, without overlaps, the entire cohort into 3 groups (clusters) with (1) low, (2) intermediate and (3) high proliferative activity. Conversely, bivariate plots exposed considerable cluster overlaps.

Oncocytic (Hürthle cell) tumors of the thyroid: distinct growth patterns comparedẁith clinicopathological features.

Neoplastic growth results from cell production that exceeds cell loss. We registered mitotic and apoptotic indices (MI and AI) in 97 immunohistochemically verified oncocytic (Hürthle cell) tumors of the thyroid (OT; 50 adenomas [OA], 20 atypical adenomas [aOA], and 27 carcinomas [OC]) and compared these kinetic data with histological diagnoses and other parameters. MI, although very low in all, was significantly higher in carcinomas than in adenomas.