Endogenous base damage as a driver of genomic instability in homologous recombination-deficient cancers.

Homologous recombination (HR) is a high-fidelity DNA double-strand break (DSB) repair pathway. Both familial and somatic loss of function mutation(s) in various HR genes predispose to a variety of cancer types, underscoring the importance of error-free repair of DSBs in human physiology. While environmental sources of DSBs have been known, more recent studies have begun to uncover the role of endogenous base damage in leading to these breaks. Base damage repair intermediates often consist of single-strand breaks, which if left unrepaired, can lead to DSBs as the replication fork encounters these lesions. This review summarizes various sources of endogenous base damage and how these lesions are repaired. We highlight how conversion of base repair intermediates, particularly those with 5'or 3' blocked ends, to DSBs can be a predominant source of genomic instability in HR-deficient cancers. We also discuss how endogenous base damage and ensuing DSBs can be exploited to enhance the efficacy of Poly (ADP-ribose) polymerase inhibitors (PARPi), that are widely used in the clinics for the regimen of HR-deficient cancers.

Antifungal metabolites produced by Pseudomonas hunanensis SPT26 effective in biocontrol of fusarium wilt of Lycopersicum esculentum under saline conditions.

In past few years, salinity has become one of the important abiotic stresses in the agricultural fields due to anthropogenic activities. Salinity is leading towards yield losses due to soil infertility and increasing vulnerability of crops to diseases. Fluorescent pseudomonads are a diverse group of soil microorganisms known for promoting plant growth by involving various traits including protecting crops from infection by the phytopathogens. In this investigation, salt tolerant plant growth promoting bacterium Pseudomonas hunanensis SPT26 was selected as an antagonist against Fusarium oxysporum, causal organism of fusarium wilt in tomato. P. hunanensis SPT26 was found capable to produce various antifungal metabolites. Characterization of purified metabolites using Fourier transform infrared spectroscopy (FT-IR) and liquid chromatography-electron spray ionization-mass spectrometry (LC-ESI/MS) showed the production of various antifungal compounds viz., pyrolnitrin, pyochelin and hyroxyphenazine by P. hunanensis SPT26. In the preliminary examination, biocontrol activity of purified antifungal metabolites was checked by dual culture method and results showed 68%, 52% and 65% growth inhibition by pyrolnitrin, 1- hydroxyphenazine and the bacterium (P. hunanensis SPT26) respectively. Images from scanning electron microscopy (SEM) revealed the damage to the mycelia of fungal phytopathogen due to production of antifungal compounds secreted by P. hunanensis SPT26. Application of bioinoculant of P. hunanensis SPT26 and purified metabolites significantly decreased the disease incidence in tomato and increased the plant growth parameters (root and shoot length, antioxidant activity, number of fruits per plant, etc.) under saline conditions. The study reports a novel bioinoculant formulation with the ability to promote plant growth parameters in tomato in presence of phytopathogens even under saline conditions.

Nucleolytic processing of abasic sites underlies PARP inhibitor hypersensitivity in ALC1-deficient BRCA mutant cancer cells.

Clinical success with poly (ADP-ribose) polymerase inhibitors (PARPi) is impeded by inevitable resistance and associated cytotoxicity. Depletion of Amplified in Liver Cancer 1 (ALC1), a chromatin-remodeling enzyme, can overcome these limitations by hypersensitizing BReast CAncer genes 1/2 (BRCA1/2) mutant cells to PARPi. Here, we demonstrate that PARPi hypersensitivity upon ALC1 loss is reliant on its role in promoting the repair of chromatin buried abasic sites. We show that ALC1 enhances the ability of the abasic site processing enzyme, Apurinic/Apyrimidinic endonuclease 1 (APE1) to cleave nucleosome-occluded abasic sites. However, unrepaired abasic sites in ALC1-deficient cells are readily accessed by APE1 at the nucleosome-free replication forks. APE1 cleavage leads to fork breakage and trapping of PARP1/2 upon PARPi treatment, resulting in hypersensitivity. Collectively, our studies reveal how cells overcome the chromatin barrier to repair abasic lesions and uncover cleavage of abasic sites as a mechanism to overcome limitations of PARPi.

18F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography and 68Ga-prostate-specific Membrane Antigen Positron Emission Tomography/Computed Tomography Imaging in the Evaluation of Rare Entity Adult Embryonal Rhabdomyosarcoma of Prostate.

A 21-year-old male with embryonal rhabdomyosarcoma of the prostate was referred for 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and 68Ga-prostate-specific membrane antigen (PSMA) PET/CT for initial disease staging. The PET scans revealed hypermetabolic and PSMA expressing lobulated mass involving both lobes of the prostate and weakly metabolic and PSMA expressing few bilateral pararectal and external iliac nodes, multiple bilateral lung nodules scattered over the lung parenchyma and multiple bone marrow lesions in both axial and appendicular skeleton. Magnetic resonance imaging prostate showed gross prostatomegaly with large lobulated T2 hyperintense heterogeneously enhancing mass lesion showing restricted diffusion, involving both lobes of the prostate with extraprostatic spread along anterior, posterior, and left lateral margins with evidence of lymph nodal and osseous metastases. The demonstration of increased uptake of 18F-FDG and 68Ga-PSMA in the primary as well as bilateral pararectal and external iliac nodes, multiple bilateral lung nodules, and multiple bone marrow lesions in both axial and appendicular skeleton indicates a potential role of 18F-FDG PET/CT and 68Ga-PSMA PET/CT in disease staging in this rare aggressive tumor of the prostate.

Prospective evaluation of 68 Ga-NODAGA-RGD PET-CT in patients of carcinoma thyroid with thyroglobulin elevated negative radioiodine scintigraphy (TENIS) with a head-to-head comparison with FDG-PET/CT.

BACKGROUND AND AIM: This study aimed to examine the expression of RGD binding integrins in patients of elevated serum thyroglobulin (Tg) level with negative radioiodine scintigraphy (TENIS) employing 68 Ga-NODAGA-RGD PET-CT. MATERIAL AND METHODS: This was a prospective study involving 30 proven cases of TENIS with histopathological diagnosis of differentiated thyroid carcinoma post-surgery. In addition to observing the lesional concentration on 68 Ga-NODAGA-RGD PET-CT, a 4-point visual grading system (grade I-IV), was undertaken to estimate the degree of radiotracer avidity, for potential of theranostics. RESULTS: On 18 F-FDG-PET/CT, the uptake was seen in 182 lesions out of a total of 200 (91%). 68 Ga-NODAGA-RGD PET-CT showed expression in a total of 110/200 (55%) lesions. On patient-specific analysis, 68 Ga-NODAGA-RGD PET-CT was positive for the disease in 21/30 patients (70%) and negative in 9/30 (30%) patients. The overall patient-specific sensitivity and specificity of 68 Ga-NODAGA-RGDPET-CT were 75% and 100%, respectively. 18 F-FDG PET-CT was positive for the disease in 26/30 patients (86.66%) and negative in 4/30 (13.33%) patients. The overall patient-specific sensitivity and specificity of 18 F-FDG-PET/CT were 92.86% and 100%, respectively. The 4-point visual grading system revealed 14/200 (7%) lesions demonstrating Grade I uptake, 49/200 (24.5%) lesions grade II uptake, 17/200 (8.5%) lesions grade III uptake and 40/200 (20%) lesions grade IV uptake. CONCLUSION: The results suggested that RGD-binding integrin is expressed in a sizeable fraction of metastatic lesions of TENIS cases, albeit demonstrating a varying degree of uptake. Out of the soft tissue, lung, and bone lesions, metastatic bone lesions showed more RGD affinity than other sites. The patients with substantial RGD uptake on a 4-point visual grading system may be potential targets for RGD-based therapy.

Rare Presentations of Differentiated Thyroid Cancer Exposing Dr Jekyll and Mr Hyde Nature of an Otherwise Indolent Disease: Case Series.

ABSTRACT: Differentiated thyroid carcinoma (DTC) usually manifests as an indolent cancer with good prognosis. However, rarely uncommon sites of metastatic involvement can worsen the prognosis and require aggressive therapeutic approach. Here in, we describe 5 patients (3 women and 2 men) harboring rare sites of metastatic involvement from DTC including the adrenals, colon, kidneys, urinary bladder, brachial plexus, and superior vena cava with contiguous right atrial involvement. The awareness of such rare sites of involvement from DTC is imperative for treating clinicians to plan individualistic approach in management including multiprong therapies for better patient care.

A high-content flow cytometry and dual CRISPR-Cas9 based platform to quantify genetic interactions.

Probing epistasis between two genes can be a critical first step in identifying the molecular players in a cellular pathway. The advent of CRISPR-Cas mediated genetic screen has enabled studying of these genetic interactions at a genomic scale. However, when combining depletion of two genes using CRISPR Cas9, reduced targeting efficiencies due to competition for Cas loading and recombination in the cloning step have emerged as key challenges. Moreover, given conventional CRISPR screens typically involve comparison between the initial and final time point, it is difficult to parse the time kinetics with which a perturbed genetic interaction impacts viability, and it also becomes challenging to assess epistasis with essential genes. Here, we discuss a high-throughput flow-based approach to study genetic interactions. By utilizing two different Cas9 orthologs and monitoring viability at multiple time points, this approach helps to effectively mitigate the limitations of Cas9 competition and enables assessment of genetic interactions with both essential and non-essential genes at a high temporal resolution.

Exogenous application of nanocarrier-mediated double-stranded RNA manipulates physiological traits and defence response against bacterial diseases.

Stability and delivery are major challenges associated with exogenous double-stranded RNA (dsRNA) application into plants. We report the encapsulation and delivery of dsRNA in cationic poly-aspartic acid-derived polymer (CPP6) into plant cells. CPP6 stabilizes the dsRNAs during long exposure at varied temperatures and pH, and protects against RNase A degradation. CPP6 helps dsRNA uptake through roots or foliar spray and facilitates systemic movement to induce endogenous gene silencing. The fluorescence of Arabidopsis GFP-overexpressing transgenic plants was significantly reduced after infiltration with gfp-dsRNA-CPP6 by silencing of the transgene compared to plants treated only with gfp-dsRNA. The plant endogenous genes flowering locus T (FT) and phytochrome interacting factor 4 (PIF4) were downregulated by a foliar spray of ft-dsRNA-CPP6 and pif4-dsRNA-CPP6 in Arabidopsis, with delayed flowering and enhanced biomass. The rice PDS gene targeted by pds-dsRNA-CPP6 through root uptake was effectively silenced and plants showed a dwarf and albino phenotype. The NaCl-induced OsbZIP23 was targeted through root uptake of bzip23-dsRNA-CPP6 and showed reduced transcripts and seedling growth compared to treatment with naked dsRNA. The negative regulators of plant defence SDIR1 and SWEET14 were targeted through foliar spray to provide durable resistance against bacterial leaf blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo). Overall, the study demonstrates that transient silencing of plant endogenous genes using polymer-encapsulated dsRNA provides prolonged and durable resistance against Xoo, which could be a promising tool for crop protection and for sustaining productivity.

68 Ga-PSMA-11 PET/CT and 64 CuCl 2 PET/CT Help in Identifying Rare Metastatic Site of Penile Shaft in a Patient of Carcinoma Prostate.

ABSTRACT: A 71-year-old man, presenting with complaints of burning sensation and pain during urination, finally diagnosed with prostate carcinoma. Ultrasonography of the abdomen and pelvis revealed prostatomegaly. Serum PSA level was elevated, and TRUS-guided biopsy demonstrated acinar adenocarcinoma (Gleason score: 5 + 4 = 9). 68 Ga-PSMA-11 PET/CT for initial staging showed PSMA-avid enlarged prostate, pelvic lymphadenopathy, and focal PSMA uptake in the left side of the shaft of the penis. The patient also underwent a 64 CuCl 2 PET/CT, which demonstrated similar findings of enlarged prostate and adenopathy with focally increased tracer uptake in the shaft of the penis coinciding with the lesion observed on 68 Ga-PSMA-11 PET/CT, thereby detecting a rare metastatic site from carcinoma prostate.