A trilocus sequence typing scheme for hospital epidemiology and subspecies differentiation of an important nosocomial pathogen, Enterococcus faecalis.

In this study, we present a trilocus sequence typing (TLST) scheme based on intragenic regions of two antigenic genes, ace and salA (encoding a collagen/laminin adhesin and a cell wall-associated antigen, respectively), and a gene associated with antibiotic resistance, lsa (encoding a putative ABC transporter), for subspecies differentiation of Enterococcus faecalis. Each of the alleles was analyzed using 50 E. faecalis isolates representing 42 diverse multilocus sequence types (ST(M); based on seven housekeeping genes) and four groups of clonally linked (by pulsed-field gel electrophoresis [PFGE]) isolates. The allelic profiles and/or concatenated sequences of the three genes agreed with multilocus sequence typing (MLST) results for typing of 49 of the 50 isolates; in addition to the one exception, two isolates were found to have identical TLST types but were single-locus variants (differing by a single nucleotide) by MLST and were therefore also classified as clonally related by MLST. TLST was also comparable to PFGE for establishing short-term epidemiological relationships, typing all isolates classified as clonally related by PFGE with the same type. TLST was then applied to representative isolates (of each PFGE subtype and isolation year) of a collection of 48 hospital isolates and demonstrated the same relationships between isolates of an outbreak strain as those found by MLST and PFGE. In conclusion, the TLST scheme described here was shown to be successful for investigating short-term epidemiology in a hospital setting and may provide an alternative to MLST for discriminating isolates.

Effects of galectin-1 and galectin-3 expression on prostate cancer cell adhesion, differentiation, proliferation, and tumorigenicity

The vertebrate $\beta$-galactoside-binding lectins galectin-1 and galectin-3 have been proposed to function in diverse cellular processes such as adhesion, proliferation, differentiation, and tumorigenesis. Experiments were initiated to further study the functional properties of these molecules. A prostate cancer cell line, LNCaP, was identified which expressed neither galectin. This line was stably transfected with cDNA for either galectin-1 or galectin-3. The resultant clones were used to study effects on critical cell processes. LNCaP cells expressing galectin-1 on the surface were found to bind more rapidly than control lines to the human extracellular matrix proteins laminin and fibronectin, although overall binding was not increased. To analyze effects on differentiation, LNCaP cells were studied which had either been transfected with galectin-1 or which had been induced to express endogenous galectin-1 by treatment with the differentiation agent sodium butyrate. In both cases, cells displayed a slower rate of growth and increased rate of apoptosis. A transient decrease in expression of prostate specific antigen was seen in the butyrate treated cells but not in the transfected cells. To investigate the role of galectins in the process of malignant transformation and progression, immunohistochemical analysis was performed on formalin-fixed, paraffin-embedded sections of human prostate tissue, the premalignant lesion prostatic intraepithelial neoplasia, primary adenocarcinoma of the prostate, and foci of metastatic prostate cancer. Galectin-1 expression was relatively constant throughout in contrast to galectin-3 which demonstrated significantly less expression in primary and metastatic tumors. LNCaP cells transfected with galectin-3 cDNA displayed lower proliferation rates, increased spontaneous apoptosis, and G1 growth phase arrest compared to controls. Four of six galectin-3 lines tested were less tumorigenic in nude mice than controls. The following conclusions are drawn regarding the role of galectin-1 and galectin-3 expression in the context of prostate cancer: (1) galectin-1 may participate in the early stages of cancer cell adhesion to extracellular matrix proteins; (2) galectin-1 expression results in a differentiated phenotype and may contribute to differentiation induction by butyrate; (3) galectin-3 expression correlates inversely with prostate cell tumorigenesis and prostate cancer metastasis. ^