Articular and Extra-Articular Benefits in ACR20 Non-responders at Week 104 Treated With Apremilast: Pooled Analysis of Three Randomized Controlled Trials.

INTRODUCTION: PALACE 1, 2, and 3 were phase 3 studies aimed to evaluate apremilast efficacy and safety in patients with active psoriatic arthritis (PsA) despite prior treatment with conventional disease-modifying anti-rheumatic drugs and/or biologics. The pooled analysis reported here further characterized the clinical outcomes associated with long-term apremilast exposure in patients failing to achieve ≥ 20% improvement in the American College of Rheumatology response criteria (ACR20) at Week 104. METHODS: Patients randomized to apremilast 30 mg twice daily at baseline and classified as ACR20 non-responders (ACR20NRs) or ACR20 responders (ACR20Rs) at Week 104 were included. Efficacy outcomes included change from baseline to Week 104 in ACR core components and other endpoints. RESULTS: At Week 104, a total of 109 patients were ACR20NRs and 193 were ACR20Rs. As expected, the ACR20R group had improvements in all indices assessed. The ACR20NR group demonstrated substantial mean improvements from baseline in swollen joint count (SJC; - 58%), tender joint count (TJC; - 42%), and Physician's Global Assessment of Disease Activity (PhGA; - 44%); resolution of enthesitis (34%) and dactylitis (68%); and achievement of ≥ 75% reduction from baseline Psoriasis Area and Severity Index scores (among patients with psoriasis involving ≥ 3% of the body surface area) (36%). CONCLUSION: Despite not fulfilling a formal ACR20 response at Week 104, ACR20NRs experienced sustained improvements in several PsA core domains, including SJC, TJC, enthesitis, dactylitis, and psoriasis, as well as the PhGA (visual analog scale) scores, with apremilast treatment. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01172938, NCT01212757, and NCT01212770.

Treatment-to-Target With Apremilast in Psoriatic Arthritis: The Probability of Achieving Targets and Comprehensive Control of Disease Manifestations.

OBJECTIVE: The present study was undertaken to evaluate the probability of achieving the Clinical Disease Activity Index for Psoriatic Arthritis (cDAPSA) treatment targets of remission or low disease activity (LDA) with apremilast based on disease activity categories and corresponding responses in arthritis and other domains of psoriatic arthritis (PsA) not included in the cDAPSA. METHODS: Pooled analyses from the Psoriatic Arthritis Long-term Assessment of Clinical Efficacy studies 1, 2, and 3 were performed. Probability analyses assessing the likelihood of achieving cDAPSA treatment targets by week 52 were performed using multiple imputation for discontinuations and missing values. Longitudinal analyses were performed in patients grouped by cDAPSA category at week 52. RESULTS: Among 494 patients in the probability analyses, 46.9% with moderate disease activity and 24.9% with high disease activity at baseline achieved treatment targets (remission or LDA) by week 52. For patients with moderate disease activity at baseline, small improvements (cDAPSA reductions ≥30%) by week 16 were associated with achieving targets. Patients achieving remission or LDA by week 16 had high probabilities of remaining at treatment targets at week 52. Of 375 patients with cDAPSA components available at week 52, achieving targets with apremilast was associated with continuous disease activity improvements and no or mild arthritis and other PsA manifestations. CONCLUSION: The probability of achieving treatment targets (remission or LDA) at week 52 was greater for patients with moderate versus high disease activity at baseline. At a mean level, partial improvements by week 16 were associated with achieving treatment targets. Patients receiving apremilast who achieved cDAPSA targets by week 52 also had no or mild arthritis or other PsA manifestations.

The Apollo 5' exonuclease functions together with TRF2 to protect telomeres from DNA repair.

A major issue in telomere research is to understand how the integrity of chromosome ends is preserved . The human telomeric protein TRF2 coordinates several pathways that prevent checkpoint activation and chromosome fusions. In this work, we identified hSNM1B, here named Apollo, as a novel TRF2-interacting factor. Interestingly, the N-terminal domain of Apollo is closely related to that of Artemis, a factor involved in V(D)J recombination and DNA repair. Both proteins belong to the beta-CASP metallo-beta-lactamase family of DNA caretaker proteins. Apollo appears preferentially localized at telomeres in a TRF2-dependent manner. Reduced levels of Apollo exacerbate the sensitivity of cells to TRF2 inhibition, resulting in severe growth defects and an increased number of telomere-induced DNA-damage foci and telomere fusions. Purified Apollo protein exhibits a 5'-to-3' DNA exonuclease activity. We conclude that Apollo is a novel component of the human telomeric complex and works together with TRF2 to protect chromosome termini from being recognized and processed as DNA damage. These findings unveil a previously undescribed telomere-protection mechanism involving a DNA 5'-to-3' exonuclease.

Targeting assay to study the cis functions of human telomeric proteins: evidence for inhibition of telomerase by TRF1 and for activation of telomere degradation by TRF2.

We investigated the control of telomere length by the human telomeric proteins TRF1 and TRF2. To this end, we established telomerase-positive cell lines in which the targeting of these telomeric proteins to specific telomeres could be induced. We demonstrate that their targeting leads to telomere shortening. This indicates that these proteins act in cis to repress telomere elongation. Inhibition of telomerase activity by a modified oligonucleotide did not further increase the pace of telomere erosion caused by TRF1 targeting, suggesting that telomerase itself is the target of TRF1 regulation. In contrast, TRF2 targeting and telomerase inhibition have additive effects. The possibility that TRF2 can activate a telomeric degradation pathway was directly tested in human primary cells that do not express telomerase. In these cells, overexpression of full-length TRF2 leads to an increased rate of telomere shortening.

The telomerase cycle: normal and pathological aspects.

Telomeres are nucleoprotein complexes that cap the end of eukaryotic chromosomes and are essential for their function and stability. Telomerase, a reverse transcriptase that extends the single-stranded G-rich 3' protruding ends of chromosomes, stabilizes telomere length in germ line cells and regenerative tissues as well as in tumor cells. In the absence of telomerase telomeres shorten with cell division, a process able to trigger cell growth arrest. When telomerase is present in the cell, its activity is tightly regulated at its site of action by factors specifically bound to the telomeric DNA. Recent data indicate that telomeres reorganize during the cell cycle. This review summarizes our current knowledge on how telomeres are dynamically organized and remodeled during cell cycle and stress response, pointing out the conservation and the difference between yeast and human. We then focus on the cellular consequences of telomere modifications in normal and cancer cells. This leads to a discussion of the different roles, seemingly contradictory, of telomeres and telomerase during the initiation and the progression of a cancer.

[Telomere and cancer: what's more at the end?]. / Télomère et cancer: quoi de plus à la fin?

Telomeres are nucleoprotein complexes that cap the end of eukaryotic chromosomes. They are essential for the functions and the stability of the genomes. There is now compelling evidences that telomerase, the enzyme that adds telomeric DNA repeats to chromosome end, is an important player in oncogenesis. The absence of telomerase in somatic tissues is thought to promote genome instability at initial stages of oncogenesis, favoring the emergence of cancer-associated chromosomal abnormalities \; restablishment of telomerase activity is expected afterwards if long term cell cycling is to occur. In addition to telomerase, various factors control the structure and function of telomeres, suggesting that additional telomeric components play important roles during oncogenesis.

Change in nuclear-cytoplasmic localization of a double-bromodomain protein during proliferation and differentiation of mouse spinal cord and dorsal root ganglia.

The human Brd2 (Bromodomain-containing 2) gene codes for a double-bromodomain protein that associates with the cell cycle-driving transcription factors E2F-1 and E2F-2. Expression of mouse Brd2 has been shown previously to be expressed in specific patterns in proliferating cells in the developing alveoli in the mammary gland. In the present study, in situ hybridization and immunohistochemical analyses were used to examine expression of Brd2 in developing neural tissues. Brd2 mRNA was detected in brain vesicles, neural tube, spinal cord and dorsal root ganglia (DRG). Immunostaining proved that the message is translated in these tissues and further revealed that Brd2 protein localizes to the nucleus in proliferating cells, but is cytoplasmic in differentiated neurons that are no longer cycling. Brd2 protein in the nuclei of the proliferating neuronal precursors is excluded from the heterochromatin. These observations are consistent with our previous finding that nuclear localization of Brd2 protein correlates with an active cell cycle in mouse mammary alveoli during the reproductive cycle, and similar results from others in cultured fibroblasts. Our findings are also consistent with the cell cycle progression/transcription coactivator function suggested by the association of Brd2 with E2F-1 and E2F-2.

[The opposite roles of telomerase during initiation and progression of cancers]. / Les rôles opposés de la télomérase pendant l'initiation et la progression des cancers.

Telomeres are nucleoprotein complexes that cap the end of eukaryotic chromosomes. They are essential for the functions and the stability of the genomes. In the absence of telomerase, the enzyme that adds telomeric DNA repeats to chromosome ends, telomeres shorten with cell division, a process thought to contribute to cell senescence. Reciprocally, telomere stabilization in immortalized cells, that usually appears concomitant with detection of telomerase activity, suggests that telomerase is essential for unlimited cell proliferation. Sequential modifications in the function of telomeres play antagonistic functions as far as tumorigenesis is concerned. Telomere dysfunction is thought to promote genome instability at initial stages, favoring the emergence of cancer-associated chromosomal abnormalities; reestablishment of telomere maintenance is expected afterwards if efficient cell cycling is to occur.

Human telomeric position effect is determined by chromosomal context and telomeric chromatin integrity.

We investigated the influence of telomere proximity and composition on the expression of an EGFP reporter gene in human cells. In transient transfection assays, telomeric DNA does not repress EGFP but rather slightly increases its expression. In contrast, in stable cell lines, the same reporter construct is repressed when inserted at a subtelomeric location. The telomeric repression is transiently alleviated by increasing the dosage of the TTAGGG repeat factor 1 (TRF1). Upon a prolongated treatment with trichostatin A, the derepression of the subtelomeric reporter gene correlates with the delocalization of HP1alpha and HP1beta. In contrast, treating the cells with 5 azacytidin, a demethylating agent, or with sirtinol, an inhibitor of the Sir2 family of deacetylase, has no apparent effect on telomeric repression. Overall, position effects at human chromosome ends are dependent on a specific higher-order organization of the telomeric chromatin. The possible involvement of HP1 isoforms is discussed.