APE1 promotes proliferation and migration of cutaneous squamous cell carcinoma

A recognition-induced three-dimensional bipedal DNA walker for highly sensitive detection of APE1

In contrast to the unipedal DNA walker, a bipedal DNA walker features a broader walking area and exhibits faster walking kinetics, leading to enhanced amplification efficiency. In this study, we designed a stochastic three-dimensional (3D) bipedal DNA walker, capable of navigating AuNP-based 3D tracks, driven by exonuclease III (Exo III). This detection system enables the linear detection of the non-invasive biomarker apurinic/apyrimidinic endonuclease 1 (APE1) activity across a range of 0 to 120 U per mL, with a detection limit of 0.03 U per mL. The platform not only offers a novel DNA walker for sensitive APE1 detection in cell lysate but also facilitates the precise assessment of NCA's inhibitory effect on APE1. This research holds promise for future screening of other potential APE1 inhibitors.

APE1 promotes radiation resistance against radiation-induced pyroptosis by inhibiting the STING pathway in lung adenocarcinoma

Mammalian apurinic/apyrimidinic endonuclease 1 (APE1, APEX1) is a multifunctional enzyme that maintains cellular homeostasis. It is involved in the base excision repair (BER) pathway and plays a key role in radiation-induced DNA damage response. However, the relationship between APE1-driven radiation resistance and pyroptosis in lung adenocarcinoma (LUAD) cells and the underlying molecular mechanisms remain unclear. We found that APE1 was significantly upregulated in LUAD tissues compared to para-carcinoma tissues and promoted the proliferation and invasion of LUAD cells in vitro and in vivo. Mechanistically, APE1 inhibited pyroptosis by inactivating the interferon gene stimulator (STING) pathway via direct interaction with AIM2 and DDX41, as detected by RNA-seq and co-immunoprecipitation. APE1 protects LUAD cells against radiation-induced damage and induces radio-resistance by targeting the STING pathway. It can induce pyroptosis and is negatively regulated by interactions with AIM2 and DDX41. Therefore, APE1 inhibitors should be considered to enhance the radiosensitivity of LUAD cells and improve patient prognosis and therapeutic outcomes. Thus, APE1 play a role in the tumor immune microenvironment and in tumor immunotherapy.

APE-1/Ref-1 Inhibition Blocks Malignant Pleural Mesothelioma Cell Proliferation and Migration: Crosstalk between Oxidative Stress and Epithelial Mesenchymal Transition (EMT) in Driving Carcinogenesis and Metastasis

Malignant pleural mesothelioma (MPM) is an aggressive cancer associated with asbestos exposure. MPM pathogenesis has been related both to oxidative stress, evoked by and in response to asbestos fibers exposure, and epithelial mesenchymal transition (EMT), an event induced by oxidative stress itself and related to cancer proliferation and metastasis. Asbestos-related primary oxidative damage is counteracted in the lungs by various redox-sensitive factors, often hyperactivated in some cancers. Among these redox-sensitive factors, Apurinic-apyrimidinic endonuclease 1 (APE-1)/Redox effector factor 1 (Ref-1) has been demonstrated to be overexpressed in MPM and lung cancer, but the molecular mechanism has not yet been fully understood. Moreover, asbestos exposure has been associated with induced EMT events, via some EMT transcription factors, such as Twist, Zeb-1 and Snail-1, in possible crosstalk with oxidative stress and inflammation events. To demonstrate this hypothesis, we inhibited/silenced Ref-1 in MPM cells; as a consequence, both EMT (Twist, Zeb-1 and Snail-1) markers and cellular migration/proliferation were significantly inhibited. Taken as a whole, these results show, for the first time, crosstalk between oxidative stress and EMT in MPM carcinogenesis and invasiveness, thus improving the knowledge to better address a preventive and therapeutic approach against this aggressive cancer.

Revisiting Two Decades of Research Focused on Targeting APE1 for Cancer Therapy: The Pros and Cons

APE1 is an essential endodeoxyribonuclease of the base excision repair pathway that maintains genome stability. It was identified as a pivotal factor favoring tumor progression and chemoresistance through the control of gene expression by a redox-based mechanism. APE1 is overexpressed and serum-secreted in different cancers, representing a prognostic and predictive factor and a promising non-invasive biomarker. Strategies directly targeting APE1 functions led to the identification of inhibitors showing potential therapeutic value, some of which are currently in clinical trials. Interestingly, evidence indicates novel roles of APE1 in RNA metabolism that are still not fully understood, including its activity in processing damaged RNA in chemoresistant phenotypes, regulating onco-miRNA maturation, and oxidized RNA decay. Recent data point out a control role for APE1 in the expression and sorting of onco-miRNAs within secreted extracellular vesicles. This review is focused on giving a portrait of the pros and cons of the last two decades of research aiming at the identification of inhibitors of the redox or DNA-repair functions of APE1 for the definition of novel targeted therapies for cancer. We will discuss the new perspectives in cancer therapy emerging from the unexpected finding of the APE1 role in miRNA processing for personalized therapy.

Apurinic/apyrimidinic endonuclease 1 mRNA level in peripheral blood neutrophils is associated with asthma

Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunc-tional key protein. Recent studies suggest APE1 is closely associated with in-flammatory response, but its role in asthma remains unknown. We recruited 116 patients with asthma, including 50 with severe asthma (NSA) and 66 with non-severe asthma (SA), and 140 controls. Serum APE1 was detected using the ELISA method. APE1 mRNA in peripheral blood neutrophils and eosinophils were detected using real-time PCR assays. Compared to healthy controls, we observed significant elevations of serum APE1 mRNA levels in peripheral neu-trophils (~1.75 folds increase, p<0.05) and eosinophils (~2.2 folds increase, p<0.05) in patients with asthma. The peripheral blood neutrophil APE1 mRNA can distinguish asthmatic patients from healthy controls with the area under the curve (AUC) 0.893 and a 95% confidence interval (CI) 0.847-0.938 (p < 0.001). Also the APE1 mRNA can identify severe asthma from non-severe asth-ma (AUC 0.759, 95% CI, 0.674-0.846; p < 0.001). However, The serum APE1 and eosinophil mRNA levels did not correlate with asthma incidence and sever-ity. Our finding confirms the association between APE1 and asthma and sug-gests that peripheral blood neutrophil APE1 mRNA may be used as a marker for this condition.

Investigating Cutaneous Squamous Cell Carcinoma in vitro and in vivo: Novel 3D Tools and Animal Models

Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients’ care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion. Extensive efforts have been made in developing new models allowing to study the molecular pathogenesis of solid tumors, including cSCC tumors. Traditionally, in vitro studies were performed with cells grown in a two-dimensional context, which, however, does not represent the complexity of tumor in vivo. In the recent years, new in vitro models have been developed aiming to mimic the three-dimensionality (3D) of the tumor, allowing the evaluation of tumor cell-cell and tumor-microenvironment interaction in an in vivo-like setting. These models include spheroids, organotypic cultures, skin reconstructs and organoids. Although 3D models demonstrate high potential to enhance the overall knowledge in cancer research, they lack systemic components which may be solved only by using animal models. Zebrafish is emerging as an alternative xenotransplant model in cancer research, offering a high-throughput approach for drug screening and real-time in vivo imaging to study cell invasion. Moreover, several categories of mouse models were developed for pre-clinical purpose, including xeno- and syngeneic transplantation models, autochthonous models of chemically or UV-induced skin squamous carcinogenesis, and genetically engineered mouse models (GEMMs) of cSCC. These models have been instrumental in examining the molecular mechanisms of cSCC and drug response in an in vivo setting. The present review proposes an overview of in vitro, particularly 3D, and in vivo models and their application in cutaneous SCC research.

MicroRNA-486-3p promotes the proliferation and metastasis of cutaneous squamous cell carcinoma by suppressing flotillin-2

BACKGROUND

Dysregulation of miR-486-3p was related to the growth and development of a variety of cancers, but the specific function of miR-486-3p in cutaneous squamous cell carcinoma (cSCC) is not to be confirmed yet.

OBJECTIVE

Our present study aimed to validate the potential molecular mechanisms of miR-486-3p in cSCC and the potential of miR-486-3p as a novel target for future treatment.

METHODS

Human cSCC samples and normal skin tissues were applied to determine the expression level of miR-486-3p and FLOT2 by fluorescence in situ hybridization (FISH) and quantitative reverse transcription PCR (qRT-PCR), respectively. As well as BALB/C nude mouse tumor model, three cSCC cells lines including HSC-1, HSC-5 and A431 were utilized to demonstrate the potential function of miR-486-3p and FLOT2 in tumorigenesis.

RESULTS

Our experimental results showed that miR-486-3p was highly expressed both in tumor samples and cell lines of cSCC. Upregulation of miR-486-3p enhanced the proliferation and migration ability of cSCC cell lines and promoted tumorigenicity in vivo. Furthermore, we confirmed that FLOT2 was a direct targeted gene of miR-486-3p. In contrary to the expression level of miR-486-3p, FLOT2 was low expressed in cSCC patient specimens and cell lines. Knockdown of FLOT2 promoted tumorigenesis of cSCC; whereas FLOT2 reversed the tumor-promoting effect of miR-486-3p.

CONCLUSION

Our data exhibited that miR-486-3p exerted its effects on carcinogenesis as an oncogene in cSCC via suppression of FLOT2. This discovery will develop new therapeutic targets of cSCC.

Anti-Cancer Activity of Phytochemicals Targeting Hypoxia-Inducible Factor-1 Alpha

Hypoxia-inducible factor-1 alpha (HIF-1α) is overexpressed in cancer, leading to a poor prognosis in patients. Diverse cellular factors are able to regulate HIF-1α expression in hypoxia and even in non-hypoxic conditions, affecting its progression and malignant characteristics by regulating the expression of the HIF-1α target genes that are involved in cell survival, angiogenesis, metabolism, therapeutic resistance, et cetera. Numerous studies have exhibited the anti-cancer effect of HIF-1α inhibition itself and the augmentation of anti-cancer treatment efficacy by interfering with HIF-1α-mediated signaling. The anti-cancer effect of plant-derived phytochemicals has been evaluated, and they have been found to possess significant therapeutic potentials against numerous cancer types. A better understanding of phytochemicals is indispensable for establishing advanced strategies for cancer therapy. This article reviews the anti-cancer effect of phytochemicals in connection with HIF-1α regulation.