This study examined the initial behaviour of 48 human oral squamous cell carcinomas (SCC) in cell culture. The early outcome of these cultures (contamination, absence of cell growth, epithelial cell senescence/fibroblast overgrowth, extended keratinocyte growth) did not reflect the clinical characteristics of the tumours of origin. Four new human oral SCC cell lines were characterized more extensively. Each cell line was immortal, 3T3-independent, and expressed low degrees of anchorage independence (CFE less than 4 per cent). Two of the four cell lines were tumorigenic in athymic mice. All of the cell lines expressed keratin intermediate filaments and two showed weak co-expression of vimentin. A wide range of keratins were expressed by the tumour xenografts; cornified keratins (K1, K10) were only expressed in the absence of K19 and vimentin, and vice versa. The nuclear:cytoplasmic ratio and the degree of serum independence correlated with each other and with the STNMP clinical grading of the tumours of origin.

Ki-67 is one of the most famous marker proteins used by histologists to identify proliferating cells. Indeed, over 30 000 articles referring to Ki-67 are listed on PubMed. Here, we review some of the current literature regarding the protein. Despite its clinical importance, our knowledge of the molecular biology and biochemistry of Ki-67 is far from complete, and its exact molecular function(s) remain enigmatic. Furthermore, reports describing Ki-67 function are often contradictory, and it has only recently become clear that this proliferation marker is itself dispensable for cell proliferation. We discuss the unusual organization of the protein and its mRNA and how they relate to various models for its function. In particular, we focus on ways in which the intrinsically disordered structure of Ki-67 might aid in the assembly of the still-mysterious mitotic chromosome periphery compartment by controlling liquid–liquid phase separation of nucleolar proteins and RNAs.

Many regulatory proteins are homo-oligomeric and designing assays that measure selfassembly will provide novel approaches to study protein allostery and screen for novel small molecule modulators of protein interactions. We present an assay to begin to define the biochemical determinants that regulate dimerization of the cancer-associated oncoprotein AGR2. A two sitesandwich microtiter assay ( 2S MTA) was designed using a DyLight800-labeled monoclonal antibody that binds to an epitope in AGR2 to screen for synthetic self-peptides that might regulate dimer stability. Peptides derived from the intrinsically disordered N-terminal region of AGR2 increase in trans oligomer stability as defined using the 2S MTA assay. A DSS-crosslinking assay that traps the AGR2 dimer through K95-K95 adducts confirmed that D45-AGR2 was a more stable dimer using denaturing gel electrophoresis. A titration of wt-AGR2, D45-AGR2 (more stable dimer), and monomeric AGR2 E60A revealed that D45-AGR2 was more active in binding to Reptin than either wt-AGR2 or the AGR2 E60A mutant. Our data have defined a functional role for the AGR2 dimer in the binding to its most well characterized interacting protein, Reptin. The ability to regulate AGR2 oligomerization in trans opens the possibility for developing small molecules that regulate its' biochemical activity as potential cancer therapeutics. The data also highlight the utility of this oligomerization assay to screen chemical libraries for ligands that could regulate AGR2 dimer stability and its' oncogenic potential.