O-GlcNAc transferase couples MRE11 to transcriptionally active chromatin to suppress DNA damage.

BACKGROUND: Transcription, metabolism and DNA damage response are tightly regulated to preserve the genomic integrity, and O-GlcNAc transferase (OGT) is positioned to connect the three. Prostate cancer is the most common cancer in men, and androgen-ablation therapy halts disease progression. However, a significant number of prostate cancer patients develop resistance against anti-androgens, and this incurable disease is termed castration-resistant prostate cancer (CRPC). We have shown that combined inhibition of OGT and the transcription elongation kinase CDK9 induce CRPC-selective anti-proliferative effects. Here, we explain the functional basis for these combinatorial effects. METHODS: We used comprehensive mass spectrometry profiling of short-term CDK9 inhibitor effects on O-GlcNAcylated proteins in an isogenic cell line system that models transition from PC to CRPC. In addition, we used both ChIP-seq and RNA-seq profiling, and pulldown experiments in multiple CRPC models. Finally, we validated our findings in prostate cancer patient samples. RESULTS: Inhibition of CDK9 results in an OGT-dependent remodeling of the proteome in prostate cancer cells. More specifically, the activity of the DNA damage repair protein MRE11 is regulated in response to CDK9 inhibition in an OGT-dependent manner. MRE11 is enriched at the O-GlcNAc-marked loci. CDK9 inhibition does not decrease the expression of mRNAs whose genes are bound by both O-GlcNAc and MRE11. Combined inhibition of CDK9 and OGT or MRE11 further decreases RNA polymerase II activity, induces DNA damage signaling, and blocks the survival of prostate cancer cells. These effects are seen in CRPC cells but not in normal prostate cells. Mechanistically, OGT activity is required for MRE11 chromatin-loading in cells treated with CDK9 inhibitor. Finally, we show that MRE11 and O-GlcNAc are enriched at the prostate cancer-specific small nucleotide polymorphic sites, and the loss of MRE11 activity results in a hyper-mutator phenotype in patient tumors. CONCLUSIONS: Both OGT and MRE11 are essential for the repair of CDK9 inhibitor-induced DNA damage. Our study raises the possibility of targeting CDK9 to elicit DNA damage in CRPC setting as an adjuvant to other treatments.

Inhibition of CDK9 activity compromises global splicing in prostate cancer cells.

Cyclin-dependent kinase 9 (CDK9) phosphorylates RNA polymerase II to promote productive transcription elongation. Here we show that short-term CDK9 inhibition affects the splicing of thousands of mRNAs. CDK9 inhibition impairs global splicing and there is no evidence for a coordinated response between the alternative splicing and the overall transcriptome. Alternative splicing is a feature of aggressive prostate cancer (CRPC) and enables the generation of the anti-androgen resistant version of the ligand-independent androgen receptor, AR-v7. We show that CDK9 inhibition results in the loss of AR and AR-v7 expression due to the defects in splicing, which sensitizes CRPC cells to androgen deprivation. Finally, we demonstrate that CDK9 expression increases as PC cells develop CRPC-phenotype both in vitro and also in patient samples. To conclude, here we show that CDK9 inhibition compromises splicing in PC cells, which can be capitalized on by targeting the PC-specific addiction androgen receptor.

Comorbidities of chronic rhinosinusitis in children and adults.

BACKGROUND: Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nose and paranasal sinuses lasting ≥12 weeks. CRS may exist with (CRSwNP) or without (CRSsNP) nasal polyps. The aim was to evaluate conditions associated with CRS in a randomized hospital cohort. We hypothesized that comorbidities and surgical procedures differ between pediatric and adult patients. METHODS: This study consisted of hospital registry data of a random sample of rhinosinusitis patients (age range 0-89 years) with the diagnosis of J32 or J33, correspondingly, registered during outpatient visits from 2005 to 2019 (n = 1461). The covariates of interest were collected from electronic health records based on ICD-10 codes and keyword searches. RESULTS: Among pediatric patients (n = 104), the relative proportions of CRSsNP and CRSwNP were 86% and 14% respectively. The relative proportions of adult patients (n = 1357) with CRSsNP and CRSwNP were 60% and 40%, respectively. The following comorbidities significantly differed (p < 0.05) between pediatric and adult populations: allergy, chronic otitis media, and tonsillar diseases. In total, 41 % of the children and 46% of the adults underwent baseline endoscopic sinus surgery (ESS). Additional surgeries of the ear, nose and pharynx were significantly more common among children compared with adults. Risk of revision after baseline ESS was associated (p < 0.05) with allergy, asthma, eosinophilia, CRSwNP, immunodeficiency or its suspicion, non-steroidal anti-inflammatory drug exacerbated respiratory disease, and number of any diseases ≥2. CONCLUSIONS: Our study showed that comorbidities differ between pediatric and adult rhinosinusitis patients, as allergy, asthma and allergy, chronic otitis media, mental health disorders, and tonsils disease were significantly more prevalent among pediatric patients. Children and adults were equally treated with ESS. Notably, children underwent additional surgery on adenoids and tonsils more frequently. The effectiveness of ESS in multimorbid adults should be assessed at an individual level.

Risk factors of NSAID-exacerbated respiratory disease: A population-based study.

BACKGROUND: Asthma with NSAID-exacerbated respiratory disease (NERD) is associated with uncontrolled or severe asthma. NERD patients are more prone to severe allergic reactions and their asthma exacerbations lead to hospitalisations twice as often compared to patients with non-NERD-asthma. NERD patients are prone to recurrent nasal polyposis requiring frequent endoscopic sinus surgeries. However, the early risk factors of NERD are not fully understood. The aim was to identify risk factors of NERD among patients with adult-onset asthma. METHODS: We used data from 1350 population-based adult asthmatics with adult-onset asthma from Finnish national registers. NERD was defined as self-reported wheeze or other typical respiratory symptoms after ingestion of NSAIDs. Thirty-six covariates covering several domains (personal characteristics, life-style, early life factors, asthma characteristics and multimorbidities) were selected based on literature and were studied in association with NERD using logistic regressions. RESULTS: The study population included 153 (11.3%) asthmatics with NERD. Thirty-six covariates were entered in univariate logistic regression analysis, in which 23 were associated with NERD (p < 0.05). These variables were entered in a multivariable logistic regression model in which allergic respiratory symptoms, female sex, osteoarthritis, difficult asthma, nasal polyps, second-hand smoke exposure at home, having 3 or more older siblings and being overweight were significantly associated with asthma with NERD (p < 0.05). Overweight decreased the risk of NERD, other factors increased it. CONCLUSION: According to our study, risk factors of NERD in part are associated with female sex, BMI, exposure to tobacco smoke, allergy, orthopaedic disorders and infection history, and their early recognition might thus be important to manage the burden of NERD.