Over the past few years, study of the rare inherited chromosome instability disorder, Fanconi Anemia (FA), has uncovered a novel DNA damage response pathway. Through the cooperation of multiple ...proteins, this pathway regulates a complicated cellular response to DNA cross-linking agents and other genotoxic stresses. In this article we review recent data identifying new components of the FA pathway that implicate it in several aspects of the DNA damage response, including the direct processing of DNA, translesion synthesis, homologous recombination, and cell cycle regulation. We also discuss new findings that explain how the FA pathway is regulated through the processes of ubiquitination and deubiquitination. We then consider the clinical implications of our current understanding of the FA pathway, particularly in the development and treatment of malignancy in heterozygous carriers of FA mutations or in patients with sporadic cancers. We consider how recent studies of p53-mediated apoptosis and loss of p53 function in models of FA may help explain the clinical features of the disease and finally present a hypothesis to account for the specificity of the FA pathway in the response to DNA cross-links.
Previously we identified a DNA damage response-deficient (DDRD) molecular subtype within breast cancer. A 44-gene assay identifying this subtype was validated as predicting benefit from DNA-damaging ...chemotherapy. This subtype was defined by interferon signaling. In this study, we address the mechanism of this immune response and its possible clinical significance.
We used immunohistochemistry (IHC) to characterize immune infiltration in 184 breast cancer samples, of which 65 were within the DDRD subtype. Isogenic cell lines, which represent DDRD-positive and -negative, were used to study the effects of chemokine release on peripheral blood mononuclear cell (PBMC) migration and the mechanism of immune signaling activation. Finally, we studied the association between the DDRD subtype and expression of the immune-checkpoint protein PD-L1 as detected by IHC. All statistical tests were two-sided.
We found that DDRD breast tumors were associated with CD4+ and CD8+ lymphocytic infiltration (Fisher's exact test P < .001) and that DDRD cells expressed the chemokines CXCL10 and CCL5 3.5- to 11.9-fold more than DNA damage response-proficient cells (P < .01). Conditioned medium from DDRD cells statistically significantly attracted PBMCs when compared with medium from DNA damage response-proficient cells (P < .05), and this was dependent on CXCL10 and CCL5. DDRD cells demonstrated increased cytosolic DNA and constitutive activation of the viral response cGAS/STING/TBK1/IRF3 pathway. Importantly, this pathway was activated in a cell cycle-specific manner. Finally, we demonstrated that S-phase DNA damage activated expression of PD-L1 in a STING-dependent manner.
We propose a novel mechanism of immune infiltration in DDRD tumors, independent of neoantigen production. Activation of this pathway and associated PD-L1 expression may explain the paradoxical lack of T-cell-mediated cytotoxicity observed in DDRD tumors. We provide a rationale for exploration of DDRD in the stratification of patients for immune checkpoint-based therapies.
Human cancers exhibit genomic instability and an increased mutation rate due to underlying defects in DNA repair. Cancer cells are often defective in one of six major DNA repair pathways, namely: ...mismatch repair, base excision repair, nucleotide excision repair, homologous recombination, nonhomologous endjoining and translesion synthesis. The specific DNA repair pathway affected is predictive of the kinds of mutations, the tumor drug sensitivity, and the treatment outcome. The study of rare inherited DNA repair disorders, such as Fanconi anemia, has yielded new insights to drug sensitivity and treatment of sporadic cancers, such as breast or ovarian epithelial tumors, in the general population. The Fanconi anemia pathway is an example of how DNA repair pathways can be deregulated in cancer cells and how biomarkers of the integrity of these pathways could be useful as a guide to cancer management and may be used in the development of novel therapeutic agents.
Background:
The critical lesion size treated with bone marrow stimulation (BMS) for osteochondral lesions of the talus (OLTs) has been 150 mm2 in area or 15 mm in diameter. However, recent ...investigations have failed to detect a significant correlation between the lesion size and clinical outcomes after BMS for OLTs.
Purpose:
To systematically review clinical studies reporting both the lesion size and clinical outcomes after BMS for OLTs.
Study Design:
Systematic review.
Methods:
A systematic search of the MEDLINE and EMBASE databases was performed in March 2015 based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Included studies were evaluated with regard to the level of evidence (LOE), quality of evidence (QOE), lesion size, and clinical outcomes.
Results:
Twenty-five studies with 1868 ankles were included; 88% were either LOE 3 or 4, and 96% did not have good QOE. The mean area was 103.8 ± 10.2 mm2 in 20 studies, and the mean diameter was 10.0 ± 3.2 mm in 5 studies. The mean American Orthopaedic Foot and Ankle Society score improved from 62.4 ± 7.9 preoperatively to 83.9 ± 9.2 at a mean 54.1-month follow-up in 14 studies reporting both preoperative and postoperative scores with a mean follow-up of more than 2 years. A significant correlation was found in 3 studies, with a mean lesion area of 107.4 ± 10.4 mm2, while none was reported in 8 studies, with a mean lesion area of 85.3 ± 9.2 mm2. The lesion diameter significantly correlated with clinical outcomes in 2 studies (mean diameter, 10.2 ± 3.2 mm), whereas none was found in 2 studies (mean diameter, 8.8 ± 0.0 mm). However, the reported lesion size measurement method and evaluation method of clinical outcomes widely varied among the studies.
Conclusion:
An assessment of the currently available data does suggest that BMS may best be reserved for OLT sizes less than 107.4 mm2 in area and/or 10.2 mm in diameter. Future development in legitimate prognostic size guidelines based on high-quality evidence that correlate with outcomes will surely provide patients with the best potential for successful long-term outcomes.
Cardiac auscultation is a key clinical skill, particularly for the diagnosis of valvular heart disease (VHD). However, its utility has declined due to the widespread availability of echocardiography ...and diminishing emphasis on the importance of clinical examination. We aim to determine the contemporary accuracy of auscultation for diagnosing VHD in primary care.
Cardiac auscultation was undertaken by one of two experienced general practitioners (primary care/family doctors) in a subset of 251 asymptomatic participants aged >65 years undergoing echocardiography within a large community-based screening study of subjects with no known VHD. Investigators were blinded to the echocardiographic findings. Newly detected VHD was classified as mild (mild regurgitation of any valve or aortic sclerosis) or significant (at least moderate regurgitation or mild stenosis of any valve).
Newly identified VHD was common, with mild disease in 170/251 participants (68%) and significant disease in 36/251 (14%). The sensitivity of auscultation was low for the diagnosis of mild VHD (32%) but slightly higher for significant VHD (44%), with specificities of 67% and 69%, respectively. Likelihood ratios were not statistically significant for the diagnosis of either mild or significant VHD in the overall cohort, but showed possible value for auscultation in non-overweight subjects (body mass index <25 kg/m
).
Cardiac auscultation has limited accuracy for the detection of VHD in asymptomatic patients and is a poor diagnostic screening tool in primary care, particularly for overweight subjects. Ensuring easy access to echocardiography in patients with symptoms suggesting VHD is likely to represent a better diagnostic strategy.
In countries with the best cancer outcomes, approximately 60% of patients receive radiotherapy as part of their treatment, which is one of the most cost-effective cancer treatments. Notably, around ...40% of cancer cures include the use of radiotherapy, either as a single modality or combined with other treatments. Radiotherapy can provide enormous benefit to patients with cancer. In the past decade, significant technical advances, such as image-guided radiotherapy, intensity-modulated radiotherapy, stereotactic radiotherapy, and proton therapy enable higher doses of radiotherapy to be delivered to the tumour with significantly lower doses to normal surrounding tissues. However, apart from the combination of traditional cytotoxic chemotherapy with radiotherapy, little progress has been made in identifying and defining optimal targeted therapy and radiotherapy combinations to improve the efficacy of cancer treatment. The National Cancer Research Institute Clinical and Translational Radiotherapy Research Working Group (CTRad) formed a Joint Working Group with representatives from academia, industry, patient groups and regulatory bodies to address this lack of progress and to publish recommendations for future clinical research. Herein, we highlight the Working Group's consensus recommendations to increase the number of novel drugs being successfully registered in combination with radiotherapy to improve clinical outcomes for patients with cancer.
Drug resistance limits the effectiveness of oesophageal adenocarcinoma (OAC) chemotherapies, leading to a poor prognosis for this disease. Elucidation of the underlying resistance mechanisms is key ...to enabling the identification of more effective treatments. This study, therefore, aims to identify novel therapeutic and/or chemotherapy sensitising drug targets in OAC. Transcriptional data from a cohort of 273 pre-treatment OAC biopsies, from patients who received neoadjuvant chemotherapy followed by surgical resection, were analysed using gene set enrichment analysis (GSEA) to determine differential gene expression between responding and non-responding OAC tumours. From this, 80 genes were selected for high-throughput siRNA screening in OAC cell lines with or without standard chemotherapy treatment. In parallel, cell viability assays were performed using a panel of FDA-approved drugs and combination index (CI) values were calculated to evaluate drug synergy with standard chemotherapy. Mechanisms of synergy were investigated using western blot, propidium iodide flow cytometry, and proliferation assays. Taken together, the screens identified that targeting Src, using either siRNA or the small molecule inhibitor dasatinib, enhanced the efficacy of chemotherapy in OAC cells. Further in vitro functional analysis confirmed Src inhibition to be synergistic with standard OAC chemotherapies, 5-fluorouracil (5-FU), and cisplatin (CDDP). In conclusion, a compound screen together with a functional genomic approach identified Src as a potential chemosensitising target in OAC, which could be assessed in a clinical study for poor prognosis OAC patients.
DNA repair deficient tumor cells have been shown to accumulate high levels of DNA damage. Consequently, these cells become hyper-dependent on DNA damage response pathways, including the ...CHK1-kinase-mediated response. These observations suggest that DNA repair deficient tumors should exhibit increased sensitivity to CHK1 inhibition. Here we offer experimental evidence in support of this hypothesis.
Using isogenic pairs of cell lines differing only in the Fanconi Anemia (FA) DNA repair pathway, we showed that FA deficient cell lines were hypersensitive to CHK1 silencing by independent siRNAs as well as CHK1 pharmacologic inhibition by Gö6976 and UCN-01. In parallel, an siRNA screen designed to identify gene silencings synthetically lethal with CHK1 inhibition identified genes required for FA pathway function. To confirm these findings in vivo, we demonstrated that whole zebrafish embryos, depleted for FANCD2 by a morpholino approach, were hypersensitive to Gö6976. Silencing of FA genes led to hyper-activation of CHK1 and vice versa. Furthermore, inactivation of CHK1 in FA deficient cell lines caused increased accumulation of DNA strand and chromosomal breakages. These results suggest that the functions subserved by CHK1 and the FA pathway mutually compensate in maintaining genome integrity. As CHK1 inhibition has been under clinical trial in combination with cisplatin, we showed that the FA specific tumoricidal effect of CHK1 inhibition and cisplatin was synergistic.
Taken together, these results suggest CHK1 inhibition as a strategy for targeting FA deficient tumors.
Formalin fixation and paraffin embedding (FFPE) is the most commonly used method worldwide for tissue storage. This method preserves the tissue integrity but causes extensive damage to nucleic acids ...stored within the tissue. As methods for measuring gene expression such as RT-PCR and microarray are adopted into clinical practice there is an increasing necessity to access the wealth of information locked in the Formalin fixation and paraffin embedding archives. This paper reviews the progress in this field and discusses the unique opportunities that exist for the application of these techniques in the development of personalized medicine.
Recognising Lung Cancer in Primary Care Bradley, Stephen H.; Kennedy, Martyn P. T.; Neal, Richard D.
Advances in therapy,
01/2019, Letnik:
36, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Significant advances in the management of both early and advanced stage lung cancer have not yet led to the scale of improved outcomes which have been achieved in other cancers over the last ...40 years. Diagnosis of lung cancer at the earliest stage of disease is strongly associated with improved survival. Therefore, although recent advances in oncology may herald breakthroughs in effective treatment, achieving early diagnosis will remain crucial to obtaining optimal outcomes. This is challenging, as most lung cancer symptoms are non-specific or are common respiratory symptoms which usually represent benign disease. Identification of patients at risk of lung cancer who require further investigation is an important responsibility for general practitioners (GPs). Diagnosis has historically relied upon plain chest X-ray (CXR), organised in response to symptoms. The sensitivity of this modality, however, compares unfavourably with that of computed tomography (CT). In some jurisdictions screening high-risk individuals with low dose CT (LDCT) is now recommended. However uptake remains low and the eligibility for screening programmes is restricted. Therefore, even if screening is widely adopted, most patients will continue to be diagnosed after presenting with symptoms. Achieving early diagnosis requires GPs to maintain an appropriate level of suspicion and readiness to investigate in high-risk patients or those with non-resolving symptoms. This article discusses the early detection of lung cancer from a primary care perspective. We outline risk factors and epidemiology, the role of screening and offer guidance on the recognition of symptomatic presentation and the investigation and referral of suspected lung cancer.
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