Analysis of active surveillance uptake for localized prostate cancer in Quebec in 2016: A Canadian bicentric study and comparison with 2010 data.

INTRODUCTION: Active surveillance (AS) has emerged as a primary management strategy for low-risk prostate cancer (PC) patients. We aimed to assess AS uptake over a 1-year snapshot throughout Quebec and to compare it to 2010 multicentric Canadian data. METHODS: A retrospective chart review and data collection was performed in 1 academic and 2 non-academic community centres from Quebec, among men identified in 2016 with localized T1c-T2c PC on biopsy, fulfilling NCCN criteria of low-risk (LR)-PC, including very-low-risk (VLR) and non-VLR-PC, and favourable-intermediate risk (FIR)-PC. AS adherence was defined when chosen as initial strategy, without any radical treatment within 6 months. RESULTS: Overall, 259 patients fulfilled the inclusion criteria with 50.2% of VLR-PC patients. At 6 months, 81% patients in the LR group and 65% in the FIR group were considered as adherent to AS, in both centres, but with an increased use of AS in the community centres compared to 2010 data. The rates of AS maintenance decreased at 12 months to respectively 69% and 58%. Among the VLR group, the rate of initiation was 98% and decreased to 85% at 12 months. CONCLUSION: Our data suggest that the majority of low-risk PC patients indeed initiated an AS in 2016, with even a greater proportion of VLR-PC patients compared to 2010. This ideal strategy should be encouraged and improved at 12 months, and assessed with recent data and longer follow-up.

Expression of a human beta-globin transgene in mice with the CACC motif and upstream sequences deleted from the promoter still depends on erythroid Krüppel-like factor.

Mice in which the erythroid Krüppel-like Factor (EKLF) gene is inactivated die in fetal life due to down-regulation of the beta-globin gene. Results have suggested that EKLF functions through the proximal CACC motif of the beta-globin promoter. For example, natural mutations of this element that fail to bind EKLF give reduced gene expression and the ability of EKLF to activate reporter genes in co-transfection assays is dependent on an intact CACC. Here, removal of the CACC motif and upstream promoter sequences from the beta-globin gene resulted in reduced expression in transgenic mice. However, breeding onto an EKLF-/- background demonstrated that a CACC-less beta-globin transgene remains highly dependent on EKLF. Hence, although the beta-globin gene partly depends on the proximal CACC motif for expression, it is unlikely that the major mechanism of gene activation by EKLF is through this element. We also show that a lacZ reporter gene linked to the beta-globin promoter, with or without the CACC box present, is actually expressed higher in EKLF-/- fetuses than in wild type animals, suggesting that EKLF may be able to act as an inhibitor of transcription with certain transgene configurations.

The beta-globin locus control region enhances transcription of but does not confer position-independent expression onto the lacZ gene in transgenic mice.

The beta-globin locus control region (LCR) confers high levels of position-independent, copy number-dependent expression onto globin transgenes. Here > 40 independent transgenic mouse lines and founders that carried the LCR in cis with the beta-globin gene promoter driving a lacZ reporter gene were studied. Expression of the lacZ transgene was assayed by measuring beta-galactosidase enzyme activity in fetal liver extracts, the levels of which correlated with the quantity of lacZ mRNA determined using RNase protection assays. Unexpectedly, expression of the lacZ transgene was found to show strong position effects, varying as much as 700-fold per transgene copy. These position effects occurred even if the whole beta-globin gene was incorporated as part of the lacZ reporter gene. Moreover, DNase I-hypersensitive sites appeared in the transgene LCR in high expressing but not in low expressing lines, suggesting that the LCR itself was position dependent. In contrast, MEL cell clones, in which transcriptionally active integration sites were selected for, gave < 13-fold variation in expression per copy of an LCR-lacZ construct. These results show that the lacZ reporter affects the ability of the LCR to activate chromatin in mice and that culture cells are not an adequate model for position-independent gene expression studies.

CAAT/enhancer-binding proteins are involved in beta-globin gene expression and are differentially expressed in murine erythroleukemia and K562 cells.

Acting in cis with the beta-globin locus control region, the CAAT box of the beta-globin gene promoter stimulates transcription 10-fold in murine erythroleukemia (MEL) cells but is without effect in K562 cells. Our previous studies suggested that of four proteins from MEL cells that bind to this CAAT box region (CP1, GATA-1, and two factors that were denoted DSFr and DSF1) DSFr is involved in the up-regulation of transcription. In the present report, the DSFr protein in MEL cells was identified as C/EBPgamma through expression cloning and antibody studies. C/EBPgamma DNA binding activity could not be detected in K562 cells. However, K562 cells, but not MEL cells, were found to express LIP, which is a truncated form of C/EBPbeta and is an inhibitor of transcription. Thus, the differential expression of C/EBP members could account for the ability of the beta-globin CAAT box to stimulate transcription in MEL cells, but not function in K562 cells. Juxtaposing a specific C/EBP binding sequence next to the beta-globin promoter, in constructs in which the CAAT box had been rendered inactive by mutation or deletion, restored full promoter activity in MEL cells only if CP1 still bound to the promoter. In conjunction with previous mutation analyses, these results suggest that C/EBPgamma may collaborate with CP1 to enhance transcription through the beta-globin CAAT box.

Activation of the beta-globin promoter by the locus control region correlates with binding of a novel factor to the CAAT box in murine erythroleukemia cells but not in K562 cells.

Four distinct factors in extracts from murine erythroleukemia (MEL) cells interacted with the human beta-globin gene promoter CAAT box: CP1, GATA-1, and two novel factors, denoted a and b, one of which is highly inducible in the MEL system. GATA-1 binding to the CAAT element was very unstable (half-life < 1 min), whereas bindings of a, b, and CP1 were comparatively stable, with half-lives of 18, 19, and 3.5 min, respectively. Stable transfections of MEL cells showed that in the presence of the beta-globin locus control region (LCR), the wild-type CAAT box, a mutant which bound to GATA-1 with increased stability over the normal sequences, and a mutant which bound a, b, and CP1 specifically could all stimulate transcription greater than ninefold over that induced by a null CAAT mutation in both uninduced and terminally differentiated MEL cells. A mutant which bound the a and b factors specifically gave only a twofold stimulation of promoter activity, and this lower activity correlated with a decrease in the stability of binding of the b protein. On the other hand, CP1 binding alone did not stimulate transcription. Taken together, these results suggest that in the context of the wild-type beta-globin CAAT element the b factor stimulates transcription directed by the LCR in MEL cells, although the LCR can also function through more stable GATA-1-binding sequences. However, in K562 cells, the wild-type beta-globin CAAT box alone was unable to stimulate gene expression directed by the LCR and high levels of transcription were obtained only upon inclusion of more upstream beta-globin promoter sequences. In contrast, a construct containing only the A gamma-globin CAAT box region did give high expression levels in K562 cells. Thus, there is a fundamental difference in the way the LCR functions in these two model systems in terms of its requirements at the promoter level.

Deletions in the dystrophin gene: analysis of Duchenne and Becker muscular dystrophy patients in Quebec.

We have analyzed patient DNA samples in 77 unrelated Duchenne (DMD) and Becker (BMD) muscular dystrophy families, 73 of which were of French Canadian origin. We show that the frequency (68%) and distribution of deletions within the dystrophin gene was neither random nor unique in this population. We localized 33% of the deletions to the proximal portion of the dystrophin gene while 63% involved the exons spanning introns 43 through 55 with breakpoint clusters occurring within introns 44 and 50. Whether the dystrophin open reading frame (ORF) is maintained constrains the distribution of DMD/BMD deletions such that BMD deletions tend to be strikingly homogeneous. Finally, the conservation of the dystrophin ORF and the severity of the clinical phenotype were concordant in 95% of the DMD/BMD deletions documented by this work.