Mucinous cancers have fewer genomic alterations than more common classes of breast cancer

Mucinous cancers of the breast are distinguished histologically by their abundant pools of mucin and low degree of nuclear pleomorphism. Relative to the more common breast cancers of no distinctive type (ductal carcinoma), mucinous cancers have a relatively favorable prognosis. In a study of chromosomal changes in mucinous cancers, we evaluated the extent of loss of heterozygosity (LOH) at chromosomal regions commonly deleted in usual infiltrating ductal carcinoma, including markers on chromosomal arms 1p, 1q, 3p, 6q, 8p, 9p, 11p, 11q, 13q, 16q, 17p, and 17q. Remarkably, we found an average frequency of LOH of only 1.9 of these 12 chromosomal arms in 18 cases of mucinous carcinoma, compared to an average frequency of LOH of 6.4 of these same chromosomal arms in cases of infiltrating ductal cancer. In three of the 18 cases of mucinous carcinoma studied, including one case with regional lymph node metastases, no LOH was seen at any of the 12 chromosomal regions studied. We considered the possibility of other chromosomal loci being more commonly affected in mucinous cancers and conducted comparative genomic hybridization on six of the cases. These studies demonstrated a low overall frequency of genomic copy number changes (mean of 3.1 changes per case) and failed to reveal any other chromosomal locus with frequent losses that had not been evaluated by microsatellite analysis. Together, these data indicate that mucinous cancers of the breast do not have the extensive genomic alterations that are typically found in more common variants of breast cancer. Thus, mucinous cancers most likely have less genetic instability than most other forms of breast cancer and the molecular pathogenesis of this form of breast cancer is likely to be substantially different than that of usual ductal breast cancer.     

Staurosporine-induced G(1) arrest in cancer cells depends on an intact pRB but is independent of p16 status

Staurosporine and its derivative 7-hydroxystaurosporine are protein kinase inhibitors that are being considered for treatments of cancers. Several recent studies have shown that cells with defective pRB protein are resistant to the G(1) cell cycle-inhibiting effects of staurosporine compounds. In this study, we examined the effect of staurosporine on two breast cancer-derived and three lung cancer-derived cell lines characterized by deficiencies in the p16 tumor suppressor. All of these p16-deficient cell lines are highly sensitive to staurosporine-induced inhibition of pRB phosphorylation and induction of arrest in G(1). This response is similar to that seen in cultured normal human bronchial epithelial cells and normal mammary epithelial cells, but strikingly different than the staurosporine resistance seen in cancer cells with defective pRB. Interestingly, inhibition of pRB phosphorylation could be seen within 4 h of treatment, suggesting that this inhibition is a consequence of direct effects of staurosporine on protein kinase(s) rather than a result of induction of other cyclin-dependent kinase inhibitors. Our findings suggest that different types of cancer cells have vastly different responses to the staurosporine class of agents, and that evaluation of pRB and p16 will help predict the response of the cancer cells to these agents.     

Pancreatic mucinous cystic neoplasms with sarcomatous stroma: molecular evidence for monoclonal origin with subsequent divergence of the epithelial and sarcomatous components.

Neoplasms with mixed carcinomatous and sarcomatous growth patterns occur in many organs and tissues. The pathogenesis of these cancers is thought to be either the result of two independent neoplastic processes merging to form a single tumor, or a neoplasm of monoclonal origin that develops phenotypic diversity. To address this issue, we characterized molecular alterations in separately microdissected epithelial and sarcomatous areas in three cases of pancreatic mucinous cystic neoplasms with sarcomatous stroma. Using microsatellite markers for six chromosomal loci commonly deleted in infiltrating ductal adenocarcinomas of the pancreas, we found genetic alterations to be virtually identical between the sarcomatous and epithelial components of two of the three neoplasms. In the third neoplasm, we found allelic losses and retentions to be identical at five of the six chromosomal loci, but at a single locus, we noted allelic loss in the neoplastic epithelial component but not the sarcomatous component. The same neoplasms were also analyzed for activating point mutations in codon 12 of the K-ras gene by using mutant-enriched polymerase chain reaction and allele-specific oligonucleotide hybridization. A K-ras mutation was identified in the epithelial component of one of the three neoplasms (the same tumor with an additional allelic loss in the neoplastic epithelial cells), but the sarcomatous component of this tumor was wild-type at codon 12 of K-ras, as were both components of the other two neoplasms. Overall, these results suggest a monoclonal origin with subsequent divergence of the neoplastic epithelial and sarcomatous portions of these neoplasms.     

A survey of domestic animals to detect serological responses against Legionella spp. by indirect fluorescent antibody

One hundred ninety-six (196) animal sera were examined for antibodies against heat-killed antigens of Legionella pneumophila serogroups 1 to 5, L. bozemanii, L. dumoffii, L. gormanii and L. micdadei by the indirect fluorescent antibody technique. Only two animals (1%), both sheep, reacted against L. pneumophila serogroups at a titer of 256. However, 29% of the horses and 24% of the sheep tested were reactive to at least one non-L. pneumophila Legionella spp. antigen at a titer of 256. At a titer of 128, 72% of the pigs, 56% of the sheep and 50% of the horses were reactive to at least one Legionella spp. antigen. Despite the presence of high antibody titers against Legionella antigens, conclusive evidence of infection by these agents in animals is dependent upon further studies.     

A Cell-penetrating Helical Polymer For siRNA Delivery to Mammalian Cells

Cell-penetrating peptides (CPPs) are routinely used for intracellular delivery of a variety of cargo, including drugs, genes, and short interfering RNA (siRNA). Most CPPs are active only upon exposure to acidic environments inside of late endosomes, thereby facilitating the endosomal escape of internalized vectors. Here, we describe the generation of a synthetic polypeptide—PVBLG_n-8—that is able to adopt a helical structure independent of pH. Like other CPPs, the helical structure of PVBLG_n-8 allows the polypeptide to destabilize membranes. However, since the helix is stable at all physiologically relevant pH values between pH 2 and pH 7.4, the membrane permeation properties of PVBLG_n-8 are irreversible. Given its pH-insensitive activity, our results suggest that PVBLG_n-8 is able to facilitate efficient siRNA delivery by causing pore formation in the cell membranes through which either free or complexed siRNA is able to diffuse. This nonspecific form of entry into the cell cytosol may prove useful when trying to deliver siRNA to cells which have proven to be difficult to transfect.