Role of p53 transcription factor in determining the efficacy of telomerase inhibitors in cancer treatment.

AIM: Telomerase expression is unique to cancer cells, making it a promising target for therapy. However, a major drawback of telomerase inhibition is that it affects cancer cell proliferation only when telomeres shorten, creating a lag phase post-continuous drug treatment. Acute cytotoxicity of telomerase inhibitors is dependent on their ability to induce DNA damage. p53 senses DNA damage and is the primary effector required for sensitizing cells towards apoptosis. MAIN METHODS: Isogenic p53+/+ and p53-/- ovarian cancer cell lines were generated using the CRISPR/Cas9 system and the anti-cancer effect of telomerase inhibitors MST-312 and BIBR1532 were determined. Flow cytometry, real-time PCR, and western blot were performed to study cell cycle, apoptosis, and gene expression. KEY FINDINGS: We report that MST-312 exhibits p53-dependent cytotoxicity, while BIBR1532 exhibits p53-independent cytotoxicity. Colony-forming ability also confirms the p53-dependent effect of MST-312. Re-expression of p53 in p53-/- cells could rescue MST-312 sensitivity. In p53+/+ cells, MST-312 causes S phase arrest and activation of p53-dependent target genes like anti-apoptosis markers (Fas and Puma) and cell cycle markers (p21 and cyclinB). In p53-/- cells, MST-312 causes S/G2/M arrest. BIBR1532 induces S/G2/M phase cell cycle arrest irrespective of p53 status. This correlates with the expression of the DNA damage marker (γ-H2AX). Long-term continuous treatment with MST-312 or BIBR1532 results in p53-independent telomere shortening. SIGNIFICANCE: In summary, we demonstrate that acute anti-cancer effects of MST-312 are dependent on p53 expression. Hence, it is important to consider the p53 expression status in cancer cells when selecting and administering telomerase inhibitors.

Optimization of Performance Parameters of the TAGGG Telomere Length Assay.

Telomeres are repetitive sequences which are present at chromosomal ends; their shortening is a characteristic feature of human somatic cells. Shortening occurs due to a problem with end replication and the absence of the telomerase enzyme, which is responsible for maintaining telomere length. Interestingly, telomeres also shorten in response to various internal physiological processes, like oxidative stress and inflammation, which may be impacted due to extracellular agents like pollutants, infectious agents, nutrients, or radiation. Thus, telomere length serves as an excellent biomarker of aging and various physiological health parameters. The TAGGG telomere length assay kit is used to quantify average telomere lengths using the telomere restriction fragment (TRF) assay and is highly reproducible. However, it is an expensive method, and because of this, it is not employed routinely for large sample numbers. Here, we describe a detailed protocol for an optimized and cost-effective measurement of telomere length using Southern blots or TRF analysis and non-radioactive chemiluminescence-based detection.

Evaluation of cardiac biomarkers in children with acute severe bronchial Asthma-A prospective study from tertiary care center in northern India.

OBJECTIVES: During the attacks of acute severe bronchial asthma there are marked cardiopulmonary changes leading to hypoxia. The study aims to find the incidence of myocardial dysfunction in patients of acute severe bronchial asthma based on cardiac enzyme levels at admission and see whether the myocardial damage is transient or persistent even after stabilization of the patient based on enzyme levels at discharge. MATERIALS AND METHODS: This prospective, case control study was done at Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University between October 2016 to May 2018. Sixty pediatric patients of acute severe bronchial asthma were taken as cases and 15 age and sex matched children served as controls. Blood samples were collected in Ethylene diamine tetra acetic acid vials before the start of treatment, for measurement of cardiac biomarkers Troponin I (TnI), Brain natriuretic peptide (BNP) and Creatine Kinase-muscle/brain (CK-MB) and repeat samples were taken before discharge. RESULTS: Fifty percent of the cases had abnormal TnI levels, 15% had abnormal CK-MB levels and 8.3% had abnormal BNP levels at admission. At discharge, only 1 (1.7%) case had abnormal levels of CK-MB, whereas the levels of TnI and BNP normalized in all. The level of cardiac biomarkers were significantly raised at admission when compared to discharge values (p value < 0.001). CONCLUSIONS: The raised cardiac biomarkers suggest myocardial stress during acute exacerbation of bronchial asthma. Though, the present study showed that the changes are of transient nature, larger follow up studies are required to document any permanent damage to myocardium.

Chest wall tuberculosis - A clinical and imaging experience.

AIMS: Tuberculous infection of the thoracic cage is rare and is difficult to discern clinically or on radiographs. This study aims to describe the common sites and the imaging appearances of chest wall tuberculosis. MATERIALS AND METHODS: A retrospective review of the clinical and imaging records of 12 confirmed cases of thoracic cage tuberculosis (excluding that of the spine), seen over the last 7 years, was performed. Imaging studies available included radiographs, ultrasonographies (USGs), and computed tomography (CT) scans. Pathological confirmation was obtained in all cases. RESULTS: All patients had clinical signs and symptoms localized to the site of involvement, whether it was the sternum, sternoclavicular joints, or ribs. CT scan revealed sternal destruction in three patients and osteolytic lesions with sclerosis of the articular surfaces of the sternoclavicular joints in two patients. In five patients with rib lesions, USG elegantly demonstrated the bone destruction underlying the cold abscess. All cases were confirmed to be of tuberculous origin by pathology studies of the aspirated/curetted material, obtained by CT / USG guidance. CONCLUSIONS: Tuberculous etiology should be considered for patients presenting with atypical sites of skeletal inflammation. CT scan plays an important role in the evaluation of these patients. However, the use of USG for demonstrating rib destruction in a chest wall cold abscess has so far been under-emphasized, as has been the role of CT and USG guided aspiration in confirming the aetiology.