scholarly journals Targeting Genome Stability in Melanoma—A New Approach to an Old Field

2021 ◽  
Vol 22 (7) ◽  
pp. 3485
Author(s):  
Marta Osrodek ◽  
Michal Wozniak
Keyword(s):  
Genome Stability ◽  
Genome Instability ◽  
Checkpoint Inhibitors ◽  
Mapk Pathway ◽  
Rapid Development ◽  
Melanoma Cells ◽  
Old Field ◽  
Number Of Patients ◽  
Recent Developments ◽  
Mapk Inhibitors

Despite recent groundbreaking advances in the treatment of cutaneous melanoma, it remains one of the most treatment-resistant malignancies. Due to resistance to conventional chemotherapy, the therapeutic focus has shifted away from aiming at melanoma genome stability in favor of molecularly targeted therapies. Inhibitors of the RAS/RAF/MEK/ERK (MAPK) pathway significantly slow disease progression. However, long-term clinical benefit is rare due to rapid development of drug resistance. In contrast, immune checkpoint inhibitors provide exceptionally durable responses, but only in a limited number of patients. It has been increasingly recognized that melanoma cells rely on efficient DNA repair for survival upon drug treatment, and that genome instability increases the efficacy of both MAPK inhibitors and immunotherapy. In this review, we discuss recent developments in the field of melanoma research which indicate that targeting genome stability of melanoma cells may serve as a powerful strategy to maximize the efficacy of currently available therapeutics.

scholarly journals Exploring the Structures and Functions of Macromolecular SLX4-Nuclease Complexes in Genome Stability

2021 ◽  
Vol 12 ◽  
Author(s):  
Brandon J. Payliss ◽  
Ayushi Patel ◽  
Anneka C. Sheppard ◽  
Haley D. M. Wyatt
Keyword(s):  
Dna Repair ◽  
Homologous Recombination ◽  
Genome Stability ◽  
Genome Instability ◽  
Strand Break ◽  
Biochemical Properties ◽  
Strand Breaks ◽  
Dna Double Strand Break ◽  
Recent Developments ◽  
And Function

All organisms depend on the ability of cells to accurately duplicate and segregate DNA into progeny. However, DNA is frequently damaged by factors in the environment and from within cells. One of the most dangerous lesions is a DNA double-strand break. Unrepaired breaks are a major driving force for genome instability. Cells contain sophisticated DNA repair networks to counteract the harmful effects of genotoxic agents, thus safeguarding genome integrity. Homologous recombination is a high-fidelity, template-dependent DNA repair pathway essential for the accurate repair of DNA nicks, gaps and double-strand breaks. Accurate homologous recombination depends on the ability of cells to remove branched DNA structures that form during repair, which is achieved through the opposing actions of helicases and structure-selective endonucleases. This review focuses on a structure-selective endonuclease called SLX1-SLX4 and the macromolecular endonuclease complexes that assemble on the SLX4 scaffold. First, we discuss recent developments that illuminate the structure and biochemical properties of this somewhat atypical structure-selective endonuclease. We then summarize the multifaceted roles that are fulfilled by human SLX1-SLX4 and its associated endonucleases in homologous recombination and genome stability. Finally, we discuss recent work on SLX4-binding proteins that may represent integral components of these macromolecular nuclease complexes, emphasizing the structure and function of a protein called SLX4IP.

scholarly journals Quantitative Tyr Phosphoproteomic Analyses Identify Cholesterol as a Master Regulator of Tumor Adaptive Resistance to MAPK Inhibition

2021 ◽  
Author(s):  
Yonghao Yu ◽  
Xu-Dong Wang ◽  
Chiho Kim ◽  
Yajie Zhang ◽  
Smita Rindhe ◽  
...  
Keyword(s):  
Rational Design ◽  
Cholesterol Metabolism ◽  
Mapk Pathway ◽  
Melanoma Cells ◽  
Mapk Signaling ◽  
Binding Motif ◽  
Master Regulator ◽  
Durable Response ◽  
Mapk Inhibitors ◽  
Targeted Inhibition

Although targeted inhibition of the MAPK pathway has achieved remarkable patient responses in many cancers with MAPK hyperactivation, the development of resistance has remained a critical challenge. Besides genomic resistance mechanisms, adaptive tumor response also underlies the resistance to targeted MAPK inhibitors. It is being increasingly appreciated that such bypass mechanisms often lead to the activation of many pro-survival kinases, which complicates the rational design of combination therapies. Here we performed global tyrosine phosphoproteomic (pTyr) analyses and demonstrated that targeted inhibition of MAPK signaling in melanoma cells leads to a profound remodeling of the pTyr proteome. Intriguingly, many of these kinases contain a cholesterol binding motif, suggesting that altered cholesterol metabolism might drive, in a coordinated fashion, the activation of these kinases. Indeed, we found a dramatic accumulation of intracellular cholesterol in melanoma cells (with BRAFV600E mutations) and non-small cell lung cancer cells (with KRASG12C mutations) treated with MAPK and KRASG12C inhibitors, respectively. Importantly, depletion of cholesterol not only prevented the MAPK inhibition-induced feedback activation of pTyr singling but also enhanced the cytotoxic effects of MAPK inhibitors, both in vitro and in vivo. Taken together, our findings provide the evidence suggesting that cholesterol functions as a master regulator of the tumor adaptive response to targeted MAPK inhibitors. These results also suggest that MAPK inhibitors could be combined with cholesterol-lowering agents to achieve a more complete and durable response in tumors with hyperactive MAPK signaling.

scholarly journals Chiral Recognition for Chromatography and Membrane-Based Separations: Recent Developments and Future Prospects

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1145
Author(s):  
Yuan Zhao ◽  
Xuecheng Zhu ◽  
Wei Jiang ◽  
Huilin Liu ◽  
Baoguo Sun
Keyword(s):  
Rapid Development ◽  
Chiral Molecules ◽  
Future Prospects ◽  
Chiral Drugs ◽  
Recognition Mechanism ◽  
Practical Applications ◽  
Food Industries ◽  
Global Industry ◽  
Endocrine Disrupting ◽  
Recent Developments

With the rapid development of global industry and increasingly frequent product circulation, the separation and detection of chiral drugs/pesticides are becoming increasingly important. The chiral nature of substances can result in harm to the human body, and the selective endocrine-disrupting effect of drug enantiomers is caused by differential enantiospecific binding to receptors. This review is devoted to the specific recognition and resolution of chiral molecules by chromatography and membrane-based enantioseparation techniques. Chromatographic enantiomer separations with chiral stationary phase (CSP)-based columns and membrane-based enantiomer filtration are detailed. In addition, the unique properties of these chiral resolution methods have been summarized for practical applications in the chemistry, environment, biology, medicine, and food industries. We further discussed the recognition mechanism in analytical enantioseparations and analyzed recent developments and future prospects of chromatographic and membrane-based enantioseparations.

scholarly journals The Efficacy of Anti-PD-L1 Treatment in Melanoma Is Associated with the Expression of the ECM Molecule EMILIN2

2021 ◽  
Vol 22 (14) ◽  
pp. 7511
Author(s):  
Albina Fejza ◽  
Maurizio Polano ◽  
Lucrezia Camicia ◽  
Evelina Poletto ◽  
Greta Carobolante ◽  
...  
Keyword(s):  
Gene Expression ◽  
Effective Treatment ◽  
Immune Checkpoint ◽  
Immune Checkpoint Inhibitors ◽  
Checkpoint Inhibitors ◽  
Tumor Hypoxia ◽  
Melanoma Cells ◽  
Vessel Normalization ◽  
Melanoma Patients

The use of immune checkpoint inhibitors has revolutionized the treatment of melanoma patients, leading to remarkable improvements in the cure. However, to ensure a safe and effective treatment, there is the need to develop markers to identify the patients that would most likely respond to the therapies. The microenvironment is gaining attention in this context, since it can regulate both the immunotherapy efficacyand angiogenesis, which is known to be affected by treatment. Here, we investigated the putative role of the ECM molecule EMILIN-2, a tumor suppressive and pro-angiogenic molecule. We verified that the EMILIN2 expression is variable among melanoma patients and is associated with the response to PD-L1 inhibitors. Consistently, in preclinical settings,the absence of EMILIN-2 is associated with higher PD-L1 expression and increased immunotherapy efficacy. We verified that EMILIN-2 modulates PD-L1 expression in melanoma cells through indirect immune-dependent mechanisms. Notably, upon PD-L1 blockage, Emilin2−/− mice displayed improved intra-tumoral vessel normalization and decreased tumor hypoxia. Finally, we provide evidence indicating that the inclusion of EMILIN2 in a number of gene expression signatures improves their predictive potential, a further indication that the analysis of this molecule may be key for the development of new markers to predict immunotherapy efficacy.

scholarly journals The Evolutionary Landscape of Treatment for BRAFV600E Mutant Metastatic Colorectal Cancer

Cancers ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 137
Author(s):  
Gianluca Mauri ◽  
Erica Bonazzina ◽  
Alessio Amatu ◽  
Federica Tosi ◽  
Katia Bencardino ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Metastatic Colorectal Cancer ◽  
Checkpoint Inhibitors ◽  
Mapk Pathway ◽  
Treatment Options ◽  
Braf Inhibitor ◽  
Current Treatment ◽  
Cytotoxic Chemotherapy ◽  
Cytotoxic Agents ◽  
Poor Prognostic Factor

The BRAFV600E mutation is found in 8–10% of metastatic colorectal cancer (mCRC) patients and it is recognized as a poor prognostic factor with a median overall survival inferior to 20 months. At present, besides immune checkpoint inhibitors (CPIs) for those tumors with concomitant MSI-H status, recommended treatment options include cytotoxic chemotherapy + anti-VEGF in the first line setting, and a combination of EGFR and a BRAF inhibitor (cetuximab plus encorafenib) in second line. However, even with the latter targeted approach, acquired resistance limits the possibility of more than an incremental benefit and survival is still dismal. In this review, we discuss current treatment options for this subset of patients and perform a systematic review of ongoing clinical trials. Overall, we identified six emerging strategies: targeting MAPK pathway (monotherapy or combinations), targeting MAPK pathway combined with cytotoxic agents, intensive cytotoxic regimen combinations, targeted agents combined with CPIs, oxidative stress induction, and cytotoxic agents combined with antiangiogenic drugs and CPIs. In the future, the integration of new therapeutic strategies targeting key players in the BRAFV600E oncogenic pathways with current treatment approach based on cytotoxic chemotherapy and surgery is likely to redefine the treatment landscape of these CRC patients.

scholarly journals PD-L1 Expression after Neoadjuvant Chemotherapy in Triple-Negative Breast Cancers Is Associated with Aggressive Residual Disease, Suggesting a Potential for Immunotherapy

Cancers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 746
Author(s):  
Beatriz Grandal ◽  
Manon Mangiardi-Veltin ◽  
Enora Laas ◽  
Marick Laé ◽  
Didier Meseure ◽  
...  
Keyword(s):  
Neoadjuvant Chemotherapy ◽  
Triple Negative ◽  
Residual Disease ◽  
Checkpoint Inhibitors ◽  
Rapid Development ◽  
Complete Response ◽  
Tumor Burden ◽  
Small Subset ◽  
Breast Cancers ◽  
Residual Cancer Burden

The consequences of neoadjuvant chemotherapy (NAC) for PD-L1 activity in triple-negative breast cancers (TNBC) are not well-understood. This is an important issue as PD-LI might act as a biomarker for immune checkpoint inhibitors’ (ICI) efficacy, at a time where ICI are undergoing rapid development and could be beneficial in patients who do not achieve a pathological complete response. We used immunohistochemistry to assess PD-L1 expression in surgical specimens (E1L3N clone, cutoff for positivity: ≥1%) on both tumor (PD-L1-TC) and immune cells (PD-L1-IC) from a cohort of T1-T3NxM0 TNBCs treated with NAC. PD-L1-TC was detected in 17 cases (19.1%) and PD-L1-IC in 14 cases (15.7%). None of the baseline characteristics of the tumor or the patient were associated with PD-L1 positivity, except for pre-NAC stromal TIL levels, which were higher in post-NAC PD-L1-TC-positive than in negative tumors. PD-L1-TC were significantly associated with a higher residual cancer burden (p = 0.035) and aggressive post-NAC tumor characteristics, whereas PD-L1-IC were not. PD-L1 expression was not associated with relapse-free survival (RFS) (PD-L1-TC, p = 0.25, and PD-L1-IC, p = 0.95) or overall survival (OS) (PD-L1-TC, p = 0.48, and PD-L1-IC, p = 0.58), but high Ki67 levels after NAC were strongly associated with a poor prognosis (RFS, p = 0.0014, and OS, p = 0.001). A small subset of TNBC patients displaying PD-L1 expression in the context of an extensive post-NAC tumor burden could benefit from ICI treatment after standard NAC.

scholarly journals 363 Vactosertib and durvalumab as second or later line treatment for PD-L1 positive non-small cell lung cancer: interim result

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A388-A388
Author(s):  
Byoung Chul Cho ◽  
Ki Hyeong Lee ◽  
Ji-Youn Han ◽  
Byoung Yong Shim ◽  
Hye Ryun Kim ◽  
...  
Keyword(s):  
Immune Checkpoint ◽  
Objective Response Rate ◽  
Immune Checkpoint Inhibitors ◽  
Advanced Nsclc ◽  
Response Rate ◽  
Checkpoint Inhibitors ◽  
Objective Response ◽  
Platinum Based Chemotherapy ◽  
Number Of Patients ◽  
Anti Tumor Activity

BackgroundTargeting transforming growth factor-β (TGF-β) is reported to augment the efficacy of immune checkpoint inhibitors (ICIs) through either enhanced anti-tumor immunity or the correction of tumor microenvironment (TME). Therefore, the combination of vactosertib, a highly selective TGF-β RI kinase inhibitor, and durvalumab is anticipated to improve anti-tumor activity of the ICI. A phase 1b/2a study was conducted to evaluate the combination of vactosertib and durvalumab in patients with advanced NSCLC who progressed after platinum-based chemotherapy.MethodsPatients were treated with vactosertib at a dose of 200 mg twice daily (five days on and two days off) and durvalumab at a dose of 1500 mg every four weeks. Eligible patients were ≥19 years old with good performance status (ECOG 0–1) and have no prior exposure to immune checkpoint inhibitors or other TGF- β R1 kinase inhibitors. The objectives of this analysis were to evaluate the safety, antitumor activity including objective response rate (ORR), duration of response (DOR), and time to response (TTR) as well as circulating pharmacodynamic biomarkers related to TGF-β signaling. Response was assessed per RECIST (v1.1).ResultsBy August 4 2020, twenty-six PD-L1 positive (SP263 assay) patients were analyzed. Median age was 61.5 years (range 48–83), 69.2% were male, median number of previous lines of chemotherapy was 1 (range 1–4), and all patients were PD-L1 positive (15 patients with PD-L1≥25% and 11 patients with PD-L1 1–24%). The most frequently reported treatment-related adverse events (TRAE) were itching (38.5%) and skin rash (34.6%), but no Gr≥3 itching and rash were observed. Each case of the following was reported as Grade 3 TRAEs: adrenal insufficiency, anemia, and pneumonitis; Grade 4 TRAE, CPK increase, was observed in one patient. Objective response rate was 30.8% and 40.0% in patients with PD-L1≥1% and ≥25% respectively. Circulating PAI-1 and CTGF evaluated in 15 patients decreased significantly on Cycle 1 day 5. Ongoing biomarker results will be presented.ConclusionsThe combination of vactosertib and durvalumab has demonstrated a manageable safety profile and encouraging anti-tumor activity as a potential therapeutic strategy in patients with advanced NSCLC. The efficacy outcomes of this combination in a larger number of patients with advanced NSCLC will be followed.Trial RegistrationNCT03732274Ethics ApprovalThe study was approved by Ethics Board of Severance Hospital (4-2018-0892), National Cancer Center (NCC2019-0057), St. Vincent’s Hospital (VC19MDDF0205), and Chungbuk National University Hospital (2019-08-015).

scholarly journals Determinants of resistance to VEGF-TKI and immune checkpoint inhibitors in metastatic renal cell carcinoma

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Revati Sharma ◽  
Elif Kadife ◽  
Mark Myers ◽  
George Kannourakis ◽  
Prashanth Prithviraj ◽  
...  
Keyword(s):  
Renal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Immune Checkpoint ◽  
Renal Cell ◽  
Immune Checkpoint Inhibitors ◽  
Kinase Inhibitors ◽  
Checkpoint Inhibitors ◽  
Resistance Mechanisms ◽  
Number Of Patients ◽  
Angiogenesis Pathway

AbstractVascular endothelial growth factor tyrosine kinase inhibitors (VEGF-TKIs) have been the mainstay of treatment for patients with advanced renal cell carcinoma (RCC). Despite its early promising results in decreasing or delaying the progression of RCC in patients, VEGF-TKIs have provided modest benefits in terms of disease-free progression, as 70% of the patients who initially respond to the treatment later develop drug resistance, with 30% of the patients innately resistant to VEGF-TKIs. In the past decade, several molecular and genetic mechanisms of VEGF-TKI resistance have been reported. One of the mechanisms of VEGF-TKIs is inhibition of the classical angiogenesis pathway. However, recent studies have shown the restoration of an alternative angiogenesis pathway in modulating resistance. Further, in the last 5 years, immune checkpoint inhibitors (ICIs) have revolutionized RCC treatment. Although some patients exhibit potent responses, a non-negligible number of patients are innately resistant or develop resistance within a few months to ICI therapy. Hence, an understanding of the mechanisms of VEGF-TKI and ICI resistance will help in formulating useful knowledge about developing effective treatment strategies for patients with advanced RCC. In this article, we review recent findings on the emerging understanding of RCC pathology, VEGF-TKI and ICI resistance mechanisms, and potential avenues to overcome these resistance mechanisms through rationally designed combination therapies.

scholarly journals Characterization of metabolic responses, genetic variations, and microsatellite instability in ammonia-stressed CHO cells grown in fed-batch cultures

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Dylan G. Chitwood ◽  
Qinghua Wang ◽  
Kathryn Elliott ◽  
Aiyana Bullock ◽  
Dwon Jordana ◽  
...  
Keyword(s):  
Microsatellite Instability ◽  
Microsatellite Loci ◽  
Cho Cells ◽  
Genome Stability ◽  
De Novo ◽  
Genome Instability ◽  
Chinese Hamster ◽  
Functional Genes ◽  
Nucleotide Polymorphisms ◽  
De Novo Mutations

Abstract Background As bioprocess intensification has increased over the last 30 years, yields from mammalian cell processes have increased from 10’s of milligrams to over 10’s of grams per liter. Most of these gains in productivity can be attributed to increasing cell densities within bioreactors. As such, strategies have been developed to minimize accumulation of metabolic wastes, such as lactate and ammonia. Unfortunately, neither cell growth nor biopharmaceutical production can occur without some waste metabolite accumulation. Inevitably, metabolic waste accumulation leads to decline and termination of the culture. While it is understood that the accumulation of these unwanted compounds imparts a suboptimal culture environment, little is known about the genotoxic properties of these compounds that may lead to global genome instability. In this study, we examined the effects of high and moderate extracellular ammonia on the physiology and genomic integrity of Chinese hamster ovary (CHO) cells. Results Through whole genome sequencing, we discovered 2394 variant sites within functional genes comprised of both single nucleotide polymorphisms and insertion/deletion mutations as a result of ammonia stress with high or moderate impact on functional genes. Furthermore, several of these de novo mutations were found in genes whose functions are to maintain genome stability, such as Tp53, Tnfsf11, Brca1, as well as Nfkb1. Furthermore, we characterized microsatellite content of the cultures using the CriGri-PICR Chinese hamster genome assembly and discovered an abundance of microsatellite loci that are not replicated faithfully in the ammonia-stressed cultures. Unfaithful replication of these loci is a signature of microsatellite instability. With rigorous filtering, we found 124 candidate microsatellite loci that may be suitable for further investigation to determine whether these loci may be reliable biomarkers to predict genome instability in CHO cultures. Conclusion This study advances our knowledge with regards to the effects of ammonia accumulation on CHO cell culture performance by identifying ammonia-sensitive genes linked to genome stability and lays the foundation for the development of a new diagnostic tool for assessing genome stability.

scholarly journals NME3 Regulates Mitochondria to Reduce ROS-Mediated Genome Instability

2020 ◽  
Vol 21 (14) ◽  
pp. 5048
Author(s):  
Chih-Wei Chen ◽  
Ning Tsao ◽  
Wei Zhang ◽  
Zee-Fen Chang
Keyword(s):  
Oxidative Stress ◽  
Dna Repair ◽  
Genome Stability ◽  
Nuclear Dna ◽  
Genome Instability ◽  
Mitochondrial Fission ◽  
Nucleoside Diphosphate Kinase ◽  
Mitochondrial Fusion ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Oxidative Stress

NME3 is a member of the nucleoside diphosphate kinase (NDPK) family that binds to the mitochondrial outer membrane to stimulate mitochondrial fusion. In this study, we showed that NME3 knockdown delayed DNA repair without reducing the cellular levels of nucleotide triphosphates. Further analyses revealed that NME3 knockdown increased fragmentation of mitochondria, which in turn led to mitochondrial oxidative stress-mediated DNA single-strand breaks (SSBs) in nuclear DNA. Re-expression of wild-type NME3 or inhibition of mitochondrial fission markedly reduced SSBs and facilitated DNA repair in NME3 knockdown cells, while expression of N-terminal deleted mutant defective in mitochondrial binding had no rescue effect. We further showed that disruption of mitochondrial fusion by knockdown of NME4 or MFN1 also caused mitochondrial oxidative stress-mediated genome instability. In conclusion, the contribution of NME3 to redox-regulated genome stability lies in its function in mitochondrial fusion.

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