AUF1 is upregulated by angiotensin II to destabilize cardiac Kv4.3 channel mRNA

Expression of cardiac myocyte Kv4 channels (Kv4.3 for human, Kv4.2 and Kv4.3 for rodents) is downregulated with hypertrophy in vivo leading to a decrease in the transient outward current (Ito). This effect is recapitulated in vitro with rat neonatal cardiac myocytes treated with angiotensin II (Ang II), which acts via AT₁ receptors, NADPH oxidase and p38 MAP kinase to destabilize the 3′ untranslated region (3′UTR) of the Kv4.3 channel messenger RNA (mRNA). Here deletion analysis and mutagenesis identify an AU-rich element (ARE) in the Kv4.3 3′UTR that is required for Ang II-induced destabilization. Overexpression of AUF1 (ARE/poly-(U)-binding/degradation factor 1), an RNA destabilizing protein, mimics and occludes the Ang II effect, while RNA interference targeted against AUF1 blocks the Ang II effect on the Kv4.3 3′UTR. Ang II upregulates AUF1 by activating AT₁ receptors, NADPH oxidase and p38 MAP kinase. Finally, pull-down assays establish that Ang II increases AUF1 binding to the ARE required for destabilization, while binding of the mRNA stabilizing protein HuR is unaffected. Hence, Ang II acts via AT₁ receptors, NADPH oxidase and p38 MAP kinase to upregulate AUF1, which in turn binds to an ARE in the Kv4.3 3′UTR to destabilize the channel mRNA.     

Evaluation of Factors in Relation with the Non-Compliance to Curative Intent Radiotherapy among Patients of Head and Neck Carcinoma: A Study from the Kumaon Region of India

Introduction:

Radiotherapy (RT)-based curative regimens for head and neck squamous cell carcinomas (HNSCC) deliver a dose of 66–70 Gray (Gy) over a period of 6–7 weeks, and incomplete treatments are unlikely to result in cure. Non-compliance to RT is major contributory factor to treatment failure.

Aims:

To assess the proportion of patients who do not complete planned treatment after initiation of curative RT. This study also aims to explore a possible relationship of non-compliance due to socio-economic, disease-related and treatment-related factors.

Materials and Methods:

The records of HNSCC patients treated from January 2012–December 2013 were audited. Data from the treatment records were to collect patient-related, disease-related, and social demographic parameters. Of the patients who had not completed treatment, the reasons behind the same were investigated.

Results:

Of the 324 patients of HNSCC who were initiated on radical RT, a total of 76 patients were found to have discontinued treatment without authorization of the treating clinician. There was no significant predilection for treatment non-compliance with regards to patient age, educational status, religion, site of the disease, use of neoadjuvant chemotherapy, or use of concurrent chemotherapy. There tended to be a higher association of treatment non-compliance among patients residing >100 km away from the treatment center, patients hailing from hilly regions, patients without the below poverty line (BPL) card, unemployed patients, and patients with stage IV-A/B disease. Of the 76 patients who did not complete treatment, telephonic questionnaire could be obtained from 54 patients. Causes for non-compliance included preference for traditional healers (22.2%), fear of toxicity (7.4%), logistic reasons (18.5%), financial reasons (24.1%), and lack of interest/faith in RT (5.6%).

Conclusion:

There is a high incidence of treatment default among patients of HNSCC during RT in this region. The revelation of the higher propensity for treatment default among patients from distant, hilly regions, unemployed, patients without BPL cards, and stages-IVA/IVB highlights the need for specific interventions for these special populations.