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Abstract Background Apurinic/apyrimidinic endonuclease 1 (APE1) imparts radio-resistance by repairing isolated lesions via the base excision repair (BER) pathway, but whether and how it is involved in the formation and/or repair of DSBs remains mostly unknown. Methods Immunoblotting, fluorescent immunostaining, and the Comet assay were used to investigate the effect of APE1 on temporal DSB formation. Chromatin extraction, 53BP1 foci and co-immunoprecipitation, and rescue assays were used to evaluate non-homologous end joining (NHEJ) repair and APE1 effects. Colony formation, micronuclei measurements, flow cytometry, and xenograft models were used to examine the effect of APE1 expression on survival and synergistic lethality. Immunohistochemistry was used to detect APE1 and Artemis expression in cervical tumor tissues. Results APE1 is upregulated in cervical tumor tissue compared to paired peri-tumor, and elevated APE1 expression is associated with radio-resistance. APE1 mediates resistance to oxidative genotoxic stress by activating NHEJ repair. APE1, via its endonuclease activity, initiates clustered lesion conversion to DSBs (within 1 h), promoting the activation of the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a key kinase in the DNA damage response (DDR) and NHEJ pathway. APE1 then participates in NHEJ repair directly by interacting with DNA- PKcs. Additionally, APE1 promotes NHEJ activity by decreasing the ubiquitination and degradation of Artemis, a nuclease with a critical role in the NHEJ pathway. Overall, APE1 deficiency leads to DSB accumulation at a late phase following oxidative stress (after 24 h), which also triggers activation of Ataxia-telangiectasia mutated (ATM), another key kinase of the DDR. Inhibition of ATM activity significantly promotes synergistic lethality with oxidative stress in APE1-deficient cells and tumors. Conclusion APE1 promotes NHEJ repair by temporally regulating DBS formation and repair following oxidative stress. This knowledge provides new insights into the design of combinatorial therapies and indicates the timing of administration and maintenance of DDR inhibitors for overcoming radio-resistance.

Chromothripsis is a catastrophic event involving numerous chromosomal rearrangements in confined genomic regions of one or a few chromosomes, causing complex effects on cells via the extensive structural variation. The development of whole-genome sequencing (WGS) has promoted great progress in exploring the mechanism and effect of chromothripsis. However, the gene expression characteristics of tumors undergone chromothripsis have not been well characterized. In this study, we found that the transcriptional profile of five tumor types experiencing chromothripsis is associated with an immune evasion phenotype. A gene set variation analysis (GSVA) was used to develop a CHP score, which is based on differentially expressed gene sets in the TCGA database, revealing that chromothripsis status in multiple cancers is consistent with an abnormal tumor immune microenvironment and immune cell cytotoxicity. Evaluation using four immunotherapy datasets uncovered the ability of the CHP score to predict immunotherapy response in diverse tumor types. In addition, the CHP score was found to be related to resistance against a variety of anti-tumor drugs, including anti-angiogenesis inhibitors and platinum genotoxins, while EGFR pathway inhibitors were found to possibly be sensitizers for high CHP score tumors. Univariate COX regression analysis indicated that the CHP score can be prognostic for several types of tumors. Our study has defined gene expression characteristics of tumors with chromothripsis, supporting the controversial link between chromothripsis and tumor immunity. We also describe the potential value of the CHP score in predicting the efficacy of immunotherapy and other treatments, elevating chromothripsis as a tool in clinical practice.

Abstract Carcinoembryonic antigen (CEA) is not only used to aid the diagnosis of lung cancer, but also help monitor recurrence and determine the prognosis of lung cancer as well as evaluate the therapeutic efficacy for lung cancer. However, studies have also shown that CEA is present at low levels in the serum of patients with benign lung diseases (BLD), which will interfere with the accurate judgment of the disease. Due to difference in sample size, detection methods, cutoff values and sources of BLD, the positive rate of CEA in BLD is different with different literature. Therefore, it is necessary to define CEA levels in patients of different BLD in a large sample study. 4796 patients with BLD were included in this study. The results showed that the CEA levels of 3.1% (149/4796) patients with BLD were elevated, with three cases exceeds 20 ng/mL (0.06%, 3/4796). The results from the literature showed that BLD had a mean positive rate of 5.99% (53/885) and only two cases had CEA above 20 ng/mL. The CEA elevations mainly distributed in chronic obstructive pulmonary disease (COPD), pneumonitis and interstitial lung disease and significantly correlated with age of patients (OR 2.69, 95% CI 1.94–3.73, p

Summary: Background: As the immune-related response evaluation criteria in solid tumors (irRECIST) by imaging greatly underestimated the objective response to immunotherapy, we established the response evaluation criteria in solid tumors based on tumor markers (RecistTM) to explore whether RecistTM can compensate for the deficiencies of the irRECIST criteria. Methods: This was an observational study, which consisted of two parts. The first part (Group A) was a retrospective study including the patients with malignant solid tumors. The second part (Group B) was a prospective study, which were EGFR-negative and ALK-negative patients with stage IIIB-IV non-small cell lung cancer receiving first-line treatment. From January 2017 to September 2020, one hundred and ten patients with a three-time increase in tumor markers receiving immunotherapy were recruited. The treatment response to immunotherapy was evaluated by irRECIST and RecistTM. Efficacy, overall survival (OS), first evaluation time and earliest response time under the different evaluation criteria were compared by statistics. Findings: The treatment response evaluated by the RecistTM criteria was not consistent with that evaluated by the irRECIST criteria (Kappa = 0.386, p

Abstract Background Although originally identified as a putative metastasis suppressor, increasing studies have confirmed a possible role for Nm23-H1 in DNA repair, through the base excision repair and nucleotide excision repair pathways. In this study, we explored whether Nm23-H1 was also involved in double-strand break repair (DSBR). Methods and results We constructed a stable A549-shNm23-H1 cell line with doxycycline-regulated expression of Nm23-H1, and a A549-nNm23-H1 cell line that over expressed a nucleus-localized version of Nm23-H1. Results from both lines confirmed that Nm23-H1 participated in the repair of double-strand breaks induced by X-rays, using Comet and γ-H2AX foci assays. Subsequent studies showed that Nm23-H1 activated the phosphorylation of checkpoint-related proteins including ATM serine/threonine kinase (on S1981), tumor protein p53 (on S15), and checkpoint kinase 2 (Chk2) (on T68). We also detected interactions between Nm23-H1 and the MRE11-RAD50-NBS1 (MRN) complex, as well as Ku80. Moreover, NBS1 and Ku80 levels were comparably higher in Nm23-H1 overexpressing cells than in control cells (t = 14.462, p

Background and objective Recent studies have indicated that Nm23-H1 is found in the nucleus, but previous studies have been based on the overexpression or suppression of Nm23-H1 in the cytoplasm. Due to the lacking nuclear localization signal of Nm23-H1, these results cannot reflect or repeat cells in which Nm23-H1 mainly positioned in nuclei and whether they cause clinical biological effects. Therefore, to explore the effects of transposing Nm23-H1 from the cytoplasm to the nucleus during lung cancer cell proliferation, a vector with a nuclear localization signal of Nm23-H1 was constructed and A549 cells were transfected. Methods Gene recombination technology was used to construct pLentis-CMV-NME1-IRES2-PURO lentiviral vectors using a nuclear localization signal sequence, and the recombinant plasmid was verified using restriction enzyme analysis and sequencing. Nm23-H1 positioning and expression were performed after the stably transfected A549 cells were assessed by Western blot and confocal laser scanning microscope. The A549 cell proliferation was assessed using a cell counting kit-8. Flow cytometry was performed to assess the cell cycle distribution of A549 cells. Results The directional Nm23-H1 lentiviral vector was successfully constructed within the nucleus. Compared with that of the empty vector group, the proliferation rates of the transfection groups at 72 h, 96 h, and 120 h were remarkably increased (P