Contributions of PARP‐1 rs1136410 C>T polymorphism to the development of cancer

Poly(ADP‐ribose) polymerase‐1 (PARP‐1) is a nuclear chromatin‐associated enzyme involved in the DNA damage response. SNP rs1136410 C>T, the most studied polymorphism in PARP‐1 gene, is highly implicated in the susceptibility of cancer. However, the roles of PARP‐1 rs1136410 C>T on cancer risk vary from different studies. We comprehensively screened all qualified publications from several databases, including PubMed, EMBASE, MEDLINE, CNKI and Wanfang. The searching was updated to April 2020. Our meta‐analysis included 60 articles with 65 studies, comprised of a total of 23 996 cases with cancer and 33 015 controls. Overall, pooled data showed that the PARP‐1 rs1136410 C>T polymorphism was significantly but a border‐line associated with an increased risk of overall cancer (CC vs. TT/TC: OR = 1.11, 95% CI = 1.00‐1.24; C vs T: OR = 1.07, 95% CI = 1.01‐1.14). Subgroup analysis indicated that rs1136410 C allele contributed to high risk among gastric, thyroid, and cervical cancer, but lower risk among brain cancer. Furthermore, increased cancer risk was detected in the subgroups of Asian, controls from population‐based design studies, and HWE ≤ 0.05 studies. Sensitivity analysis and Egger''s test showed that results of the meta‐analysis were fairly stable. The current study indicated that PARP1 rs1136410 C>T polymorphism may have an impact on certain types of cancer susceptibility.     

Attenuation of SARS‐CoV‐2 replication and associated inflammation by concomitant targeting of viral and host cap 2'‐O‐ribose methyltransferases

The SARS‐CoV‐2 infection cycle is a multistage process that relies on functional interactions between the host and the pathogen. Here, we repurposed antiviral drugs against both viral and host enzymes to pharmaceutically block methylation of the viral RNA 2''‐O‐ribose cap needed for viral immune escape. We find that the host cap 2''‐O‐ribose methyltransferase MTr1 can compensate for loss of viral NSP16 methyltransferase in facilitating virus replication. Concomitant inhibition of MTr1 and NSP16 efficiently suppresses SARS‐CoV‐2 replication. Using in silico target‐based drug screening, we identify a bispecific MTr1/NSP16 inhibitor with anti‐SARS‐CoV‐2 activity in vitro and in vivo but with unfavorable side effects. We further show antiviral activity of inhibitors that target independent stages of the host SAM cycle providing the methyltransferase co‐substrate. In particular, the adenosylhomocysteinase (AHCY) inhibitor DZNep is antiviral in in vitro, in ex vivo, and in a mouse infection model and synergizes with existing COVID‐19 treatments. Moreover, DZNep exhibits a strong immunomodulatory effect curbing infection‐induced hyperinflammation and reduces lung fibrosis markers ex vivo. Thus, multispecific and metabolic MTase inhibitors constitute yet unexplored treatment options against COVID‐19.     

DNA asymmetry promotes SUMO modification of the single‐stranded DNA‐binding protein RPA

Repair of DNA double‐stranded breaks by homologous recombination (HR) is dependent on DNA end resection and on post‐translational modification of repair factors. In budding yeast, single‐stranded DNA is coated by replication protein A (RPA) following DNA end resection, and DNA–RPA complexes are then SUMO‐modified by the E3 ligase Siz2 to promote repair. Here, we show using enzymatic assays that DNA duplexes containing 3'' single‐stranded DNA overhangs increase the rate of RPA SUMO modification by Siz2. The SAP domain of Siz2 binds DNA duplexes and makes a key contribution to this process as highlighted by models and a crystal structure of Siz2 and by assays performed using protein mutants. Enzymatic assays performed using DNA that can accommodate multiple RPA proteins suggest a model in which the SUMO‐RPA signal is amplified by successive rounds of Siz2‐dependent SUMO modification of RPA and dissociation of SUMO‐RPA at the junction between single‐ and double‐stranded DNA. Our results provide insights on how DNA architecture scaffolds a substrate and E3 ligase to promote SUMO modification in the context of DNA repair.     

ERCC1 and ERCC2 Haplotype Modulates Induced BPDE-DNA Adducts in Primary Cultured Lymphocytes

Background

Benzo[a]pyrene(B[a]P), and its ultimate metabolite Benzo[a]pyrene 7,8-diol 9,10-epoxide (BPDE), are classic DNA damaging carcinogens. DNA damage caused by BPDE is normally repaired by Nucleotide Excision Repair (NER), of which ERCC1 and ERCC2/XPD exert an indispensable role. Genetic variations in ERCC1 and ERCC2 have been related to DNA repair efficiency. In this study we used lymphocytes from healthy individuals to show that polymorphisms in ERCC1 and ERCC2 are directly associated with decreased DNA repair efficiency.

Methods

ERCC1 (rs3212986 and rs11615) and ERCC2 (rs13181, rs1799793 and rs238406) were genotyped in 818 healthy Han individuals from the northeast of China. BPDE induced DNA adducts in lymphocytes were assessed by high performance liquid chromatography (HPLC) in 282 randomly selected participants. The effect of ERCC1 rs3212986 and ERCC2 rs238406 on DNA damage caused by B[a]P was assessed with a modified comet assay.

Results

We found that the variant genotypes of ERCC1 rs3212986 and ERCC2 rs238406 were associated with the high levels of BPDE-DNA adducts. Especially ERCC1 rs3212986 A-allele variant was significantly associated with the high BPDE-DNA adducts. Haplotype analysis showed that the ERCC1 haplotype AC (OR = 2.36, 95% CI = 1.84–2.97), ERCC2 haplotype AGA (OR = 1.51, 95% CI = 1.06–2.15) and haplotype block AGAAC (OR = 5.28, 95% CI = 2.95–9.43), AGCAC (OR = 1.35 95% CI = 1.13–1.60) were linked with high BPDE-DNA adducts. In addition, we found that the combined minor alleles of ERCC1 rs3212986 and ERCC2 rs238406 were associated with a reduced DNA repair capacity.

Conclusions

Our results suggest that the variant genotypes of ERCC1 rs3212986 and ERCC2 rs238406 are associated with decreased repair efficiency of BPDE induced DNA damage, and may be predictive for an individual’s DNA repair capacity in response to environmental carcinogens.     

Characterizing heterogeneity of non‐small cell lung tumour microenvironment to identify signature prognostic genes

Growing evidence has highlighted the immune response as an important feature of carcinogenesis and therapeutic efficacy in non‐small cell lung cancer (NSCLC). This study focused on the characterization of immune infiltration profiling in patients with NSCLC and its correlation with survival outcome. All TCGA samples were divided into three heterogeneous clusters based on immune cell profiles: cluster 1 (''low infiltration'' cluster), cluster 2 (''heterogeneous infiltration'' cluster) and cluster 3 (''high infiltration'' cluster). The immune cells were responsible for a significantly favourable prognosis for the ''high infiltration'' community. Cluster 1 had the lowest cytotoxic activity, tumour‐infiltrating lymphocytes and interferon‐gamma (IFN‐γ), as well as immune checkpoint molecules expressions. In addition, MHC‐I and immune co‐stimulator were also found to have lower cluster 1 expressions, indicating a possible immune escape mechanism. A total of 43 differentially expressed genes (DEGs) that overlapped among the groups were determined based on three clusters. Finally, based on a univariate Cox regression model, prognostic immune‐related genes were identified and combined to construct a risk score model able to predict overall survival (OS) rates in the validation datasets.     

The determination of relationship between “excision repair cross-complementing group 1” (ERCC1) gene T19007C and C8092A single nucleotide polymorphisms and clinicopathological parameters in non-small cell lung cancer

DNA repair plays a key role in prevention of carcinogenesis and one of the most important DNA repair mechanisms is nucleotide excision repair (NER) pathway. This pathway includes a number of genes such as excision repair cross-complementing group 1 (ERCC1) gene which are responsible for the 5′ incision of damaged DNA. A reduced DNA repair capacity associated with ERCC1 mRNA level has been observed in lung carcinogenesis. Two single nucleotide polymorphisms (SNPs) in ERCC1 gene, T19007C (rs11615) and C8092A (rs3212986), reportedly predict to affect the mRNA of ERCC1 in non-small cell lung cancer (NSCLC). To examine the role of two common SNPs in ERCC1 gene further, we conducted this study where 80 cases histopatologically diagnosed as NSCLC were genotyped. Genomic DNA was extracted from formalin-fixed, paraffin embedded tissues and two SNPs were analyzed using real-time PCR. The distributions of TT, TC, and CC genotypes of the T19007C SNP were 40, 44 and 16%, respectively. Significantly increased frequency of the patients carrying at least one 19007C allele was observed in early stage compared to advanced stage (P = 0.002). And also, the frequency of TC and CC genotypes significantly increased in younger patients compared to older patients (P = 0.035). Regarding C8092A SNP, the distribution of CC, CA, and AA genotypes was 38, 51 and 11%, respectively. There was no significant difference in the genotype distribution between C8092A SNP and clinicopathological parameters. This study indicated that harboring at least one 19007C allele may have protective effect in NSCLC.     

Circular RNA hsa_circ_0008003 facilitates tumorigenesis and development of non‐small cell lung carcinoma via modulating miR‐488/ZNF281 axis

As one of the most aggressive malignancies, non‐small cell lung carcinoma (NSCLC) has high risks of death. It has been demonstrated that circRNAs accelerate NSCLC progression, but the underlying molecular mechanisms of circRNAs in NSCLC were still obscure. In the first place, the circRNA microarray of NSCLC was investigated in this study, and hsa_circ_0008003 (circ‐0008003) was chosen as the research object. Then, it was unveiled that the expression of circ‐0008003 examined via qRT‐PCR was elevated in tumour tissues relative to the non‐tumour tissues, which was associated with TNM stage and lymphatic metastasis in NSCLC. Additionally, the prognosis of NSCLC patients with high circ‐0008003 level was poor. Besides, circ‐0008003 silencing dampened the invasion and proliferation of NSCLC cells. Next, according to the mechanistic studies, circ‐0008003 functioned as a ceRNA of ZNF281 in NSCLC by acting as the endogenous sponge for miR‐488, which was proved to be a tumour suppressor in NSCLC. Additionally, ZNF281 overexpression and miR‐488 suppression recovered the influences of repressed circ‐0008003 on NSCLC cellular processes. It was validated in this research that circ‐0008003 triggered tumour formation in NSCLC, which was adjusted via miR‐488/ZNF281 axis, casting a novel light on the resultful target for treating NSCLC and predicting the prognosis.     

On‐site genetic analysis for species identification using lab‐on‐a‐chip

This paper presents a microfluidic device capable of performing genetic analysis on dung samples to identify White Rhinoceros (Ceratotherium simum). The development of a microfluidic device, which can be used in the field, offers a portable and cost‐effective solution for DNA analysis and species identification to aid conservation efforts. Optimization of the DNA extraction processes produced equivalent yields compared to conventional kit‐based methods within just 5 minutes. The use of a color‐changing loop‐mediated isothermal amplification reaction for simultaneous detection of the cytochrome B sequence of C. simum enabled positive results to be obtained within as little as 30 minutes. Field testing was performed at Knowsley Safari to demonstrate real‐world applicability of the microfluidic device for testing of biological samples.     

Interleukin‐37 improves T‐cell‐mediated immunity and chimeric antigen receptor T‐cell therapy in aged backgrounds

Aging‐associated declines in innate and adaptive immune responses are well documented and pose a risk for the growing aging population, which is predicted to comprise greater than 40 percent of the world''s population by 2050. Efforts have been made to improve immunity in aged populations; however, safe and effective protocols to accomplish this goal have not been universally established. Aging‐associated chronic inflammation is postulated to compromise immunity in aged mice and humans. Interleukin‐37 (IL‐37) is a potent anti‐inflammatory cytokine, and we present data demonstrating that IL‐37 gene expression levels in human monocytes significantly decline with age. Furthermore, we demonstrate that transgenic expression of interleukin‐37 (IL‐37) in aged mice reduces or prevents aging‐associated chronic inflammation, splenomegaly, and accumulation of myeloid cells (macrophages and dendritic cells) in the bone marrow and spleen. Additionally, we show that IL‐37 expression decreases the surface expression of programmed cell death protein 1 (PD‐1) and augments cytokine production from aged T‐cells. Improved T‐cell function coincided with a youthful restoration of Pdcd1, Lat, and Stat4 gene expression levels in CD4⁺ T‐cells and Lat in CD8⁺ T‐cells when aged mice were treated with recombinant IL‐37 (rIL‐37) but not control immunoglobin (Control Ig). Importantly, IL‐37‐mediated rejuvenation of aged endogenous T‐cells was also observed in aged chimeric antigen receptor (CAR) T‐cells, where improved function significantly extended the survival of mice transplanted with leukemia cells. Collectively, these data demonstrate the potency of IL‐37 in boosting the function of aged T‐cells and highlight its therapeutic potential to overcome aging‐associated immunosenescence.     

Predictive value of ERCC1 single-nucleotide polymorphism in patients receiving platinum-based chemotherapy for locally-advanced and advanced non-small cell lung cancer--a pilot study

Platinum-based chemotherapy is the main type of I-line treatment of advanced and non-operative NSCLC patients without EGFR gene mutation. The excision repair cross-complementation group 1 (ERCC1) is an enzyme that executes the incision of the damaged DNA strand and removes platinum-induced DNA adducts. We investigated whether ERCC1 gene polymorphism has an effect on the response to chemotherapy and survival in 43 patients with NSCLC treated with platinum-based chemotherapy. ERCC1 19007 T>C SNPs were assessed using a PCR-RFLP methods in DNA isolated from peripheral blood lymphocytes. Disease control occurred significantly (p = 0.045) more frequently in patients with CC or CT genotype compared to patients with TT genotype. Median PFS and OS for CC homozygous were 4 and 10.5 months, 4 and 12.5 months for CT heterozygous, but only 0.3 and 1.5 months for TT homozygous patients, respectively. The probability of PFS was significantly higher (HR = 0.438, 95% CI: 0.084-0.881, p = 0.03) and probability of OS was insignificantlyhigher (HR = 0.503, 95% CI: 0.129-1.137, p = 0.084) in patients with CC or CT genotype than in patients with TT genotype. Uncommon TT genotype of ERCC1 19007 T>C polymorphism could predict poor response and shortening of progression free survival in NSCLC patients treated with platinum-based I-line chemotherapy. The analysis of this polymorphism may serve as a promising tool in the qualification of advanced NSCLC patients for appropriate chemotherapy.     

RNA‐binding protein RBM47 stabilizes IFNAR1 mRNA to potentiate host antiviral activity

The type I interferon (IFN‐I, IFN‐α/β)‐mediated immune response is the first line of host defense against invading viruses. IFN‐α/β binds to IFN‐α/β receptors (IFNARs) and triggers the expression of IFN‐stimulated genes (ISGs). Thus, stabilization of IFNARs is important for prolonging antiviral activity. Here, we report the induction of an RNA‐binding motif‐containing protein, RBM47, upon viral infection or interferon stimulation. Using multiple virus infection models, we demonstrate that RBM47 has broad‐spectrum antiviral activity in vitro and in vivo. RBM47 has no noticeable impact on IFN production, but significantly activates the IFN‐stimulated response element (ISRE) and enhances the expression of interferon‐stimulated genes (ISGs). Mechanistically, RBM47 binds to the 3''UTR of IFNAR1 mRNA, increases mRNA stability, and retards the degradation of IFNAR1. In summary, this study suggests that RBM47 is an interferon‐inducible RNA‐binding protein that plays an essential role in enhancing host IFN downstream signaling.     

A virus‐derived microRNA targets immune response genes during SARS‐CoV‐2 infection

SARS‐CoV‐2 infection results in impaired interferon response in patients with severe COVID‐19. However, how SARS‐CoV‐2 interferes with host immune responses is incompletely understood. Here, we sequence small RNAs from SARS‐CoV‐2‐infected human cells and identify a microRNA (miRNA) derived from a recently evolved region of the viral genome. We show that the virus‐derived miRNA produces two miRNA isoforms in infected cells by the enzyme Dicer, which are loaded into Argonaute proteins. Moreover, the predominant miRNA isoform targets the 3′UTR of interferon‐stimulated genes and represses their expression in a miRNA‐like fashion. Finally, the two viral miRNA isoforms were detected in nasopharyngeal swabs from COVID‐19 patients. We propose that SARS‐CoV‐2 can potentially employ a virus‐derived miRNA to hijack the host miRNA machinery, which could help to evade the interferon‐mediated immune response.     

O‐GlcNAcylation of TDP‐43 suppresses proteinopathies and promotes TDP‐43’s mRNA splicing activity

Pathological TDP‐43 aggregation is characteristic of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD‐TDP); however, how TDP‐43 aggregation and function are regulated remain poorly understood. Here, we show that O‐GlcNAc transferase OGT‐mediated O‐GlcNAcylation of TDP‐43 suppresses ALS‐associated proteinopathies and promotes TDP‐43''s splicing function. Biochemical and cell‐based assays indicate that OGT''s catalytic activity suppresses TDP‐43 aggregation and hyperphosphorylation, whereas abolishment of TDP‐43 O‐GlcNAcylation impairs its RNA splicing activity. We further show that TDP‐43 mutations in the O‐GlcNAcylation sites improve locomotion defects of larvae and adult flies and extend adult life spans, following TDP‐43 overexpression in Drosophila motor neurons. We finally demonstrate that O‐GlcNAcylation of TDP‐43 promotes proper splicing of many mRNAs, including STMN2, which is required for normal axonal outgrowth and regeneration. Our findings suggest that O‐GlcNAcylation might be a target for the treatment of TDP‐43‐linked pathogenesis.     

C1632 suppresses the migration and proliferation of non‐small‐cell lung cancer cells involving LIN28 and FGFR1 pathway

Chemoresistance and migration represent major obstacles in the therapy of non‐small‐cell lung cancer (NSCLC), which accounts for approximately 85% of lung cancer patients in clinic. In the present study, we report that the compound C1632 is preferentially distributed in the lung after oral administration in vivo with high bioavailability and limited inhibitory effects on CYP450 isoenzymes. We found that C1632 could simultaneously inhibit the expression of LIN28 and block FGFR1 signalling transduction in NSCLC A549 and A549R cells, resulting in significant decreases in the phosphorylation of focal adhesion kinase and the expression of matrix metalloproteinase‐9. Consequently, C1632 effectively inhibited the migration and invasion of A549 and A549R cells. Meanwhile, C1632 significantly suppressed the cell viability and the colony formation of A549 and A549R cells by inhibiting DNA replication and inducing G0/G1 cell cycle arrest. Interestingly, compared with A549 cells, C1632 possesses the same or even better anti‐migration and anti‐proliferation effects on A549R cells, regardless of drug resistance. In addition, C1632 also displayed the capacity to inhibit the growth of A549R xenograft tumours in mice. Altogether, these findings reveal the potential of C1632 as a promising anti‐NSCLC agent, especially for chemotherapy‐resistant NSCLC treatment.     

Genetic prediction of ICU hospitalization and mortality in COVID‐19 patients using artificial neural networks

There is an unmet need of models for early prediction of morbidity and mortality of Coronavirus disease‐19 (COVID‐19). We aimed to a) identify complement‐related genetic variants associated with the clinical outcomes of ICU hospitalization and death, b) develop an artificial neural network (ANN) predicting these outcomes and c) validate whether complement‐related variants are associated with an impaired complement phenotype. We prospectively recruited consecutive adult patients of Caucasian origin, hospitalized due to COVID‐19. Through targeted next‐generation sequencing, we identified variants in complement factor H/CFH, CFB, CFH‐related, CFD, CD55, C3, C5, CFI, CD46, thrombomodulin/THBD, and A Disintegrin and Metalloproteinase with Thrombospondin motifs (ADAMTS13). Among 381 variants in 133 patients, we identified 5 critical variants associated with severe COVID‐19: rs2547438 (C3), rs2250656 (C3), rs1042580 (THBD), rs800292 (CFH) and rs414628 (CFHR1). Using age, gender and presence or absence of each variant, we developed an ANN predicting morbidity and mortality in 89.47% of the examined population. Furthermore, THBD and C3a levels were significantly increased in severe COVID‐19 patients and those harbouring relevant variants. Thus, we reveal for the first time an ANN accurately predicting ICU hospitalization and death in COVID‐19 patients, based on genetic variants in complement genes, age and gender. Importantly, we confirm that genetic dysregulation is associated with impaired complement phenotype.     

Population genetic structure and evolution of Batesian mimicry in Papilio polytes from the Ryukyu Islands,Japan, analyzed by genotyping‐by‐sequencing

Batesian mimicry is a striking example of Darwinian evolution, in which a mimetic species resembles toxic or unpalatable model species, thereby receiving protection from predators. In some species exhibiting Batesian mimicry, nonmimetic individuals coexist as polymorphism in the same population despite the benefits of mimicry. In a previous study, we proposed that the abundance of mimics is limited by that of the models, leading to polymorphic Batesian mimicry in the swallowtail butterfly, Papilio polytes, on the Ryukyu Islands in Japan. We found that their mimic ratios (MRs), which varied among the Islands, were explained by the model abundance of each habitat, rather than isolation by distance or phylogenetic constraint based on the mitochondrial DNA (mtDNA) analysis. In the present study, this possibility was reexamined based on hundreds of nuclear single nucleotide polymorphisms (SNPs) of 93 P. polytes individuals from five Islands of the Ryukyus. We found that the population genetic and phylogenetic structures of P. polytes largely corresponded to the geographic arrangement of the habitat Islands, and the genetic distances among island populations show significant correlation with the geographic distances, which was not evident by the mtDNA‐based analysis. A partial Mantel test controlling for the present SNP‐based genetic distances revealed that the MRs of P. polytes were strongly correlated with the model abundance of each island, implying that negative frequency‐dependent selection interacting with model species shaped and maintained the mimetic polymorphism. Taken together, our results support the possibility that predation pressure, not isolation by distance or other neutral factors, is a major driving force of evolution of the Batesian mimicry in P. polytes from the Ryukyus.     

Novel long non‐coding RNA CYB561‐5 promotes aerobic glycolysis and tumorigenesis by interacting with basigin in non‐small cell lung cancer

Abnormally expressed long non‐coding RNAs (lncRNAs) have been recognized as potential diagnostic biomarkers or therapeutic targets in non‐small cell lung cancer (NSCLC). The role of the novel lnc‐CYB561‐5 in NSCLC and its specific biological activity remain unknown. In this study, lncRNAs highly expressed in NSCLC tissue samples compared with paired adjacent normal tissue samples and atypical adenomatous hyperplasia were identified by RNA‐seq analysis. Lnc‐CYB561‐5 is highly expressed in human NSCLC and is associated with a poor prognosis in lung adenocarcinoma. In vivo, downregulation of lnc‐CYB561‐5 significantly decreases tumour growth and metastasis. In vitro, lnc‐CYB561‐5 knockdown treatment inhibits cell migration, invasion and proliferation ability, as well as glycolysis rates. In addition, RNA pulldown and RNA immunoprecipitation (RIP) assays show that basigin (Bsg) protein interacts with lnc‐CYB561‐5. Overall, this study demonstrates that lnc‐CYB561‐5 is an oncogene in NSCLC, which is involved in the regulation of cell proliferation and metastasis. Lnc‐CYB561‐5 interacts with Bsg to promote the expression of Hk2 and Pfk1 and further lead to metabolic reprogramming of NSCLC cells.     

Polymorphisms in ERCC1 and XPF Genes and Risk of Gastric Cancer in an Eastern Chinese Population

Background

Inherited functional single nucleotide polymorphisms (SNPs) in DNA repair genes may alter DNA repair capacity and thus contribute to cancer risk.

Methods

Three ERCC1 functional SNPs (rs2298881C>A, rs3212986C>A and rs11615G>A) and two XPF/ERCC4 functional SNPs (rs2276466C>G and rs6498486A>C) were genotyped for 1125 gastric adenocarcinoma cases and 1196 cancer-free controls by Taqman assays. Odds ratios (OR) and 95% confidence intervals (CI) were used to estimate risk associations, and false-positive report probabilities (FPRP) were calculated for assessing significant findings.

Results

ERCC1 rs2298881C and rs11615A variant genotypes were associated with increased gastric cancer risk (adjusted OR = 1.33, 95% CI = 1.05–1.67 for rs2298881 AC/CC and adjusted OR = 1.23, 95% CI = 1.05–1.46 for rs11615 AG/AA, compared with their common genotype AA and GG, respectively). Patients with 2–3 ERCC1 risk genotypes had significant increased risk (adjusted OR = 1.56, 95% CI = 1.27–1.93), compared with those with 0–1 ERCC1 risk genotypes, and this risk was more significantly in subgroups of never drinkers, non-gastric cardia adenocarcinoma (NGCA) and clinical stage I+II. All these risks were not observed for XPF SNPs.

Conclusions

These findings suggest that functional ERCC1 SNPs may contribute to risk of gastric cancer. Larger and well-designed studies with different ethnic populations are needed to validate our findings.     

A new family of CRISPR‐type V nucleases with C‐rich PAM recognition

Most CRISPR‐type V nucleases are stimulated to cleave double‐stranded (ds) DNA targets by a T‐rich PAM, which restricts their targeting range. Here, we identify and characterize a new family of type V RNA‐guided nuclease, Cas12l, that exclusively recognizes a C‐rich (5''‐CCY‐3′) PAM. The organization of genes within its CRISPR locus is similar to type II‐B CRISPR‐Cas9 systems, but both sequence analysis and functional studies establish it as a new family of type V effector. Biochemical experiments show that Cas12l nucleases function optimally between 37 and 52°C, depending on the ortholog, and preferentially cut supercoiled DNA. Like other type V nucleases, it exhibits collateral nonspecific ssDNA and ssRNA cleavage activity that is triggered by ssDNA or dsDNA target recognition. Finally, we show that one family member, Asp2Cas12l, functions in a heterologous cellular environment, altogether, suggesting that this new group of CRISPR‐associated nucleases may be harnessed as genome editing reagents.