ROS-dependent DNA damage and repair during germination of NaCl primed seeds

Iron metabolism and the tumor microenvironment: A new perspective on cancer intervention and therapy (Review)

Iron metabolism plays a crucial role in the tumor microenvironment, influencing various aspects of cancer cell biology and tumor progression. This review discusses the regulatory mechanisms of iron metabolism within the tumor microenvironment and highlights how tumor cells and associated stromal cells manage iron uptake, accumulation and regulation. The sources of iron within tumors and the biological importance of ferroptosis in cancer were explored, focusing on its mechanisms, biological effects and, in particular, its tumor‑suppressive properties. Furthermore, the protective strategies employed by cancer cells to evade ferroptosis were examined. This review also delves into the intricate relationship between iron metabolism and immune modulation within the tumor microenvironment, detailing the impact on tumor‑associated immune cells and immune evasion. The interplay between ferroptosis and immunotherapy is discussed and potential strategies to enhance cancer immunotherapy by modulating iron metabolism are presented. Finally, the current ferroptosis‑based cancer therapeutic approaches were summarized and future directions for therapies that target iron metabolism were proposed.

Exploring the Genotoxic Stress Response in Primed Orphan Legume Seeds Challenged with Heat Stress

BACKGROUND/OBJECTIVES

The increased frequency of extreme weather events related to climate change, including the occurrence of extreme temperatures, severely affects crop yields, impairing global food security. Heat stress resulting from temperatures above 30 °C is associated with poor germination performance and stand establishment. The combination of climate-resilient crop genotypes and tailored seed priming treatments might represent a reliable strategy to overcome such drawbacks. This work explores the potential of hydropriming as a tool to mitigate the heat-stress-mediated impact on germination performance in orphan legumes.

METHODS

For each tested species (Lathyrus sativus L., Pisum sativum var. arvense and Trigonella foenum-graecum L.), two accessions were investigated. Germination tests were performed at 25 °C, 30 °C, 35 °C and 40 °C to assess the heat stress tolerance threshold. Hydropriming was then applied and germination tests were performed at 40 °C to test the impact of the treatment on the seeds' ability to cope with heat stress. An alkaline comet assay and Quantitative Real Time-Polymerase Chain Reaction were performed on embryos excised from primed and control seeds.

RESULTS

Phenotyping at the germination and seedling development stage highlighted the accession-specific beneficial impact of hydropriming under heat stress conditions. In L. sativus seeds, the alkaline comet assay revealed the dynamics of heat stress-induced DNA damage accumulation, as well as the repair patterns promoted by hydropriming. The expression patterns of genes involved in DNA repair and antioxidant response were consistently responsive to the hydropriming and heat wave conditions in L. sativus accessions.

PARP1 inhibitor niraparib exerts synergistic antimyeloma effect with bortezomib through inducing DNA damage and inhibiting DNA repair

Despite the improvements in outcomes for patients with multiple myeloma (MM) over the past decade, the disease remains incurable, and even those patients who initially respond favorably to induction therapy eventually suffer from relapse. Consequently, there is an urgent need for the development of novel therapeutic agents and strategies to enhance the treatment outcomes for patients with MM. The proteasome inhibitor bortezomib (BTZ) elicits endoplasmic reticulum (ER) stress and oxidative stress in MM cells, subsequent DNA damage, ultimately inducing cell apoptosis. Poly (ADP-ribose) polymerase 1 (PARP1) acts as a pivotal enzyme for DNA repair and thus deficient PARP1 renders cells more susceptible to DNA-damaging agents. Conceivably, targeting PARP1 may enhance BTZ-induced DNA damage and cell death in MM cells. In this study, Colony formation, CCK-8, and EdU-labeling assays were conducted to evaluate the effects on MM cell proliferation. The ZIP score was used to assess synergy. Apoptosis and intercellular ROS levels were analyzed using flow cytometry and fluorescence microscopy, respectively. Immunofluorescence and Western blot analyses were used to assess protein expression. The correlation between PARP1 expression levels and the clinical prognosis was examined by tumor-related databases and bioinformatics. The results show that PARP1 is overexpressed in patient MM cells and is associated with a poor prognosis. PARP1 inhibitor niraparib decreases MM cell growth and arrests cell cycle progression at the G2/M phase. When combined with BTZ, it synergistically increases DNA damage, inhibits proliferation, and induces apoptosis. Mechanistically, Niraparib facilitates BTZ-induced ROS elevation, causing DNA double-strand breaks (DSBs), and simultaneously inhibits lesion repair by impeding the expression of repair proteins XRCC1 (X-ray repair cross-complementing protein 1) and POLβ (DNA polymerase beta). Overall, Niraparib plus bortezomib represent a promising approach for treatment of MM.

The micro(nano)plastics perspective: exploring cancer development and therapy

Microplastics, as an emerging environmental pollutant, have received widespread attention for their potential impact on ecosystems and human health. Microplastics are defined as plastic particles less than 5 millimeters in diameter and can be categorized as primary and secondary microplastics. Primary microplastics usually originate directly from industrial production, while secondary microplastics are formed by the degradation of larger plastic items. Microplastics are capable of triggering cytotoxicity and chronic inflammation, and may promote cancer through mechanisms such as pro-inflammatory responses, oxidative stress and endocrine disruption. In addition, improved microplastics bring new perspectives to cancer therapy, and studies of microplastics as drug carriers are underway, showing potential for high targeting and bioavailability. Although current studies suggest an association between microplastics and certain cancers (e.g., lung, liver, and breast cancers), the long-term effects and specific mechanisms still need to be studied. This review aimed at exploring the carcinogenicity of microplastics and their promising applications in cancer therapy provides important directions for future research and emphasizes the need for multidisciplinary collaboration to address this global health challenge.

Hallmarks of DNA Damage Response in Germination Across Model and Crop Species

DNA damage response (DDR) contributes to seed quality by guarding genome integrity in the delicate phases of pre- and post-germination. As a key determinant of stress tolerance and resilience, DDR has notable implications on the wider scale of the agroecosystems challenged by harsh climatic events. The present review focuses on the existing and documented links that interconnect DDR efficiency with an array of molecular hallmarks with biochemical, molecular, and physiological valence within the seed metabolic networks. The expression of genes encoding DDR sensors, transducers, mediators, and effectors is interpreted as a source of conserved hallmarks, along with markers of oxidative damage reflecting the seed's ability to germinate. Similarly, the accumulation patterns of proteins and metabolites that contribute to DNA stability are predictive of seed quality traits. While a list of candidates is presented from multiple models and crop species, their interaction with chromatin dynamics, cell cycle progression, and hormonal regulation provides further levels of analysis to investigate the seed stress response holistically. The identification of novel hallmarks of DDR in seeds constitutes a framework to prompt validation with different experimental systems, to refine the current models of pre-germinative metabolism, and to promote targeted approaches for seed quality evaluation.

Hyposalinity elicits physiological responses and alters intestinal microbiota in Korean rockfish Sebastes schlegelii

Global warming significantly impacts aquatic ecosystems, with changes in the salt environment negatively affecting the physiological responses of fish. We investigated the impact of hyposalinity on the physiological responses and intestinal microbiota of Sebastes schlegelii under the context of increased freshwater influx due to climate change. We focused on the osmoregulatory capacity, oxidative stress responses, and alterations in the intestinal microbiome of S. schlegelii under low-salinity conditions. Our findings revealed compromised osmoregulatory capacity in S. schlegelii under low-salinity conditions, accompanied by the activation of oxidative stress responses, indicating physiological adaptations to cope with environmental stress. Specifically, changes in Na+/K+-ATPase (NKA) activity in gill tissues were associated with decreased osmoregulatory capacity. Furthermore, the analysis of the intestinal microbiome led to significant changes in microbial diversity. Exposure to low-salinity environments led to dysbiosis, with notable decreases in the relative abundance of Gammaproteobacteria at the class level and specific genera such as Enterovibrio, and Photobacterium. Conversely, Bacilli classes, along with genera like Mycoplasma, exhibited increased proportions in fish exposed to low-salinity conditions. These findings underscore the potential impact of environmental salinity changes on the adaptive capacity of fish species, particularly in the context of aquaculture. Moreover, they highlight the importance of considering both physiological and microbial responses in understanding the resilience of aquatic organisms to environmental stress. Additionally, they highlight the importance of intestinal microbiota analyses in understanding the immune system and disease management in fish.

Arabidopsis DNA glycosylase MBD4L improves recovery of aged seeds

DNA glycosylases initiate the base excision repair (BER) pathway by catalyzing the removal of damaged or mismatched bases from DNA. The Arabidopsis DNA glycosylase methyl-CpG-binding domain protein 4 like (MBD4L) is a nuclear enzyme triggering BER in response to the genotoxic agents 5-fluorouracil and 5-bromouracil. To date, the involvement of MBD4L in plant physiological processes has not been analyzed. To address this, we studied the enzyme functions in seeds. We found that imbibition induced the MBD4L gene expression by generating two alternative transcripts, MBD4L.3 and MBD4L.4. Gene activation was stronger in aged than in non-aged seeds. Seeds from mbd4l-1 mutants displayed germination failures when maintained under control or ageing conditions, while 35S:MBD4L.3/mbd4l-1 and 35S:MBD4L.4/mbd4l-1 seeds reversed these phenotypes. Seed nuclear DNA repair, assessed by comet assays, was exacerbated in an MBD4L-dependent manner at 24 h post-imbibition. Under this condition, the BER genes ARP, APE1L, and LIG1 showed higher expression in 35S:MBD4L.3/mbd4l-1 and 35S:MBD4L.4/mbd4l-1 than in mbd4l-1 seeds, suggesting that these components could coordinate with MBD4L to repair damaged DNA bases in seeds. Interestingly, the ATM, ATR, BRCA1, RAD51, and WEE1 genes associated with the DNA damage response (DDR) pathway were activated in mbd4l-1, but not in 35S:MBD4L.3/mbd4l-1 or 35S:MBD4L.4/mbd4l-1 seeds. These results indicate that MBD4L is a key enzyme of a BER cascade that operates during seed imbibition, whose deficiency would cause genomic damage detected by DDR, generating a delay or reduction in germination.

Melatonin Priming Promotes Crop Seed Germination and Seedling Establishment Under Flooding Stress by Mediating ABA, GA, and ROS Cascades

Both seed germination and subsequent seedling establishment are key checkpoints during the life cycle of seed plants, yet flooding stress markedly inhibits both processes, leading to economic losses from agricultural production. Here, we report that melatonin (MT) seed priming treatment enhances the performance of seeds from several crops, including soybean, wheat, maize, and alfalfa, under flooding stress. Transcriptome analysis revealed that MT priming promotes seed germination and seedling establishment associated with changes in abscisic acid (ABA), gibberellin (GA), and reactive oxygen species (ROS) biosynthesis and signaling pathways. Real-time quantitative RT-PCR (qRT-PCR) analysis confirmed that MT priming increases the expression levels of GA biosynthesis genes, ABA catabolism genes, and ROS biosynthesis genes while decreasing the expression of positive ABA regulatory genes. Further, measurements of ABA and GA concentrations are consistent with these trends. Following MT priming, quantification of ROS metabolism-related enzyme activities and the concentrations of H2O2 and superoxide anions (O2 -) after MT priming were consistent with the results of transcriptome analysis and qRT-PCR. Finally, exogenous application of GA, fluridone (an ABA biosynthesis inhibitor), or H2O2 partially rescued the poor germination of non-primed seeds under flooding stress. Collectively, this study uncovers the application and molecular mechanisms underlying MT priming in modulating crop seed vigor under flooding stress.

Aging-Induced Reduction in Safflower Seed Germination via Impaired Energy Metabolism and Genetic Integrity Is Partially Restored by Sucrose and DA-6 Treatment

Seed storage underpins global agriculture and the seed trade and revealing the mechanisms of seed aging is essential for enhancing seed longevity management. Safflower is a multipurpose oil crop, rich in unsaturated fatty acids that are at high risk of peroxidation as a contributory factor to seed aging. However, the molecular mechanisms responsible for safflower seed viability loss are not yet elucidated. We used controlled deterioration (CDT) conditions of 60% relative humidity and 50 °C to reduce germination in freshly harvested safflower seeds and analyzed aged seeds using biochemical and molecular techniques. While seed malondialdehyde (MDA) and fatty acid content increased significantly during CDT, catalase activity and soluble sugar content decreased. KEGG analysis of gene function and qPCR validation indicated that aging severely impaired several key functional and biosynthetic pathways including glycolysis, fatty acid metabolism, antioxidant activity, and DNA replication and repair. Furthermore, exogenous sucrose and diethyl aminoethyl hexanoate (DA-6) treatment partially promoted germination in aged seeds, further demonstrating the vital role of impaired sugar and fatty acid metabolism during the aging and recovery processes. We concluded that energy metabolism and genetic integrity are impaired during aging, which contributes to the loss of seed vigor. Such energy metabolic pathways as glycolysis, fatty acid degradation, and the tricarboxylic acid cycle (TCA) are impaired, especially fatty acids produced by the hydrolysis of triacylglycerols during aging, as they are not efficiently converted to sucrose via the glyoxylate cycle to provide energy supply for safflower seed germination and seedling growth. At the same time, the reduced capacity for nucleotide synthesis capacity and the deterioration of DNA repair ability further aggravate the damage to DNA, reducing seed vitality.

Ultrasonic seed treatment improved seed germination, growth, and yield of rice by modulating associated physio-biochemical mechanisms

Ultrasonic seed (US) treatment could alter seed germination mechanism, however, US induced alterations in morph-physiological attributes and yield of fragrant rice were rarely reported. In the present study, the seeds of three fragrant rice cultivars viz., Xiangyaxiangzhan, Meixiangzhan 2, Ruanhuayou 6100 and one non-fragrant rice viz., Wufengyou 615 were exposed to ultrasonic waves at 20-40 kHz for 1.5 min (T) whereas the seeds without exposure were taken as control (CK). Results showed that US treatment caused minor cracks on seed surface while improved seed germination rate (1.79 %-11.09 %) and 3-indoleacetic acid (IAA) (3.36 %-46.91 %). Furthermore, peroxidase (POD) activity and methionine sulfoxide reductase activity was increased by 29.15 %-74.13 % and 11.26 %-20.87 %, respectively; however, methionine sulfoxide reductase related protein repairing gene MSRA4 was down-regulated by 17.93 % -41.04 % under T, compared to CK. Besides, US treatment also improved soluble protein in flag leaf (0.92 %-40.79 %), photosynthesis (3.37 %-16.46 %), biomass (5.17 %-31.87 %), as well as 2-acetyl-1-pyrroline content (4.77 %-15.48 %) in rice grains. In addition, multivariate analysis showed that the dry weight at the maturity stage were significantly related to the POD, glutathione reductase (GR) activity, IAA, and abscisic acid (ABA) content while germination rate was positively related to the GR activity, ABA content, and yield, but which were negatively related to the IAA and gibberellic acid content.

Novel roles of PIWI proteins and PIWI-interacting RNAs in human health and diseases

Non-coding RNA has aroused great research interest recently, they play a wide range of biological functions, such as regulating cell cycle, cell proliferation, and intracellular substance metabolism. Piwi-interacting RNAs (piRNAs) are emerging small non-coding RNAs that are 24-31 nucleotides in length. Previous studies on piRNAs were mainly limited to evaluating the binding to the PIWI protein family to play the biological role. However, recent studies have shed more lights on piRNA functions; aberrant piRNAs play unique roles in many human diseases, including diverse lethal cancers. Therefore, understanding the mechanism of piRNAs expression and the specific functional roles of piRNAs in human diseases is crucial for developing its clinical applications. Presently, research on piRNAs mainly focuses on their cancer-specific functions but lacks investigation of their expressions and epigenetic modifications. This review discusses piRNA's biogenesis and functional roles and the recent progress of functions of piRNA/PIWI protein complexes in human diseases. Video Abstract.

Profiling of Barley, Wheat, and Rye FPG and OGG1 Genes during Grain Germination

This research is about the profiling of barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), and rye (Secale cereale L.) FPG and OGG1 genes during grain germination. During seed germination, reactive oxygen species accumulate, which leads to DNA damage. In the base excision repair (BER) system, the enzymes formamidopyrimidine DNA glycosylase (FPG) and 8-oxoguanine DNA glycosylase (OGG1), among others, are responsible for repairing such damage. We decided to check how the expression of genes encoding these two enzymes changes in germinating grains. Spring varieties of barley, wheat, and rye from the previous growing season were used in the study. Expression level changes were checked using Real-Time PCR. After analyzing the obtained results, the maximum expression levels of FPG and OGG1 genes during germination were determined for barley, wheat, and rye. The results of the study show differences in expression levels specific to each species. The highest expression was observed at different time points for each of them. There were no differences in the highest expression for FPG and OGG1 within one species. In conclusion, the research provides information on how the level of FPG and OGG1 gene expression changes during the germination process in cereals. This is the first study looking at the expression levels of these two genes in cereals.

Seed Nano-Priming with Calcium Oxide Maintains the Redox State by Boosting the Antioxidant Defense System in Water-Stressed Carom (Trachyspermum ammi L.) Plants to Confer Drought Tolerance

This paper explores the potential of nano seed priming with calcium oxide nanoparticles in maintaining the redox status in carom (Trachyspermum ammi L.) plants by modulating non-enzymatic antioxidants and enzymatic antioxidants. Calcium oxide nanoparticles were prepared in four testing regimes comprising 25, 50, 75, and 100 ppm along with the control treatment of 0 ppm (distilled water). Priming was performed by soaking the carom seeds in the aerated water, and plants were grown under split plots corresponding to drought and water. Seed priming with 75 ppm CaONPs reduced hydrogen peroxide, malondialdehyde contents and electrolyte leakage by 23.3%, 35.9% and 31.6%, respectively, in the water-stressed carom plants. The glutathione s-transferase, superoxide dismutase and peroxidase functions improved under water stress by 42.3%, 24.1% and 44.8%, respectively, in the carom plants raised through 100 ppm primed seeds with CaO_NPs. Priming induced better Ca²⁺ signaling, which affected the enzymes of the ascorbate glutathione cycle, enabling them to maintain redox status in the carom plants exposed to drought stress. The morpho-agronomic traits of carom plants in terms of number of umbels, hundred seeds weights, shoot and root length and biomass improved significantly upon seed priming treatments. Seed priming with CaO_NPs is a viable strategy to combat reactive oxygen species-mediated damages in the carom plants.

Molecular dynamics of seed priming at the crossroads between basic and applied research

The potential of seed priming is still not fully exploited. Our limited knowledge of the molecular dynamics of seed pre-germinative metabolism is the main hindrance to more effective new-generation techniques. Climate change and other recent global crises are disrupting food security. To cope with the current demand for increased food, feed, and biofuel production, while preserving sustainability, continuous technological innovation should be provided to the agri-food sector. Seed priming, a pre-sowing technique used to increase seed vigor, has become a valuable tool due to its potential to enhance germination and stress resilience under changing environments. Successful priming protocols result from the ability to properly act on the seed pre-germinative metabolism and stimulate events that are crucial for seed quality. However, the technique still requires constant optimization, and researchers are committed to addressing some key open questions to overcome such drawbacks. In this review, an update of the current scientific and technical knowledge related to seed priming is provided. The rehydration-dehydration cycle associated with priming treatments can be described in terms of metabolic pathways that are triggered, modulated, or turned off, depending on the seed physiological stage. Understanding the ways seed priming affects, either positively or negatively, such metabolic pathways and impacts gene expression and protein/metabolite accumulation/depletion represents an essential step toward the identification of novel seed quality hallmarks. The need to expand the basic knowledge on the molecular mechanisms ruling the seed response to priming is underlined along with the strong potential of applied research on primed seeds as a source of seed quality hallmarks. This route will hasten the implementation of seed priming techniques needed to support sustainable agriculture systems.

Sunflower Bark Extract as a Biostimulant Suppresses Reactive Oxygen Species in Salt-Stressed Arabidopsis

A survey of plant-based wastes identified sunflower (Helianthus annuus) bark extract (SBE), produced via twin-screw extrusion, as a potential biostimulant. The addition of SBE to Arabidopsis (Arabidopsis thaliana) seedlings cultured in vitro showed a dose-dependent response, with high concentrations causing severe growth inhibition. However, when priming seeds with SBE, a small but significant increase in leaf area was observed at a dose of 0.5 g of lyophilized powder per liter. This optimal concentration of SBE in the culturing medium alleviated the growth inhibition caused by 100 mM NaCl. The recovery in shoot growth was accompanied by a pronounced increase in photosynthetic pigment levels and a stabilization of osmotic homeostasis. SBE-primed leaf discs also showed a similar protective effect. SBE mitigated salt stress by reducing the production of reactive oxygen species (ROS) (e.g., hydrogen peroxide) by about 30% and developing more expanded true leaves. This reduction in ROS levels was due to the presence of antioxidative agents in SBE and by activating ROS-eliminating enzymes. Polyphenols, carbohydrates, proteins, and other bioactive compounds detected in SBE may have contributed to the cellular redox homeostasis in salt-stressed plants, thus promoting early leaf development by relieving shoot apical meristem arrest. Sunflower stalks from which SBE is prepared can therefore potentially be valorized as a source to produce biostimulants for improving salt stress tolerance in crops.

Differential Gene Expression and Withanolides Biosynthesis During in vitro and ex vitro Growth of Withania somnifera (L.) Dunal

Ashwagandha (Withania somnifera L. Dunal) is a medicinally important plant with withanolides as its major bioactive compounds, abundant in the roots and leaves. We examined the influence of plant growth regulators (PGRs) on direct organogenesis, adventitious root development, withanolide biosynthetic pathway gene expression, withanolide contents, and metabolites during vegetative and reproductive growth phases under in vitro and ex vitro conditions. The highest shooting responses were observed with 6-benzylaminopurine (BAP) (2.0 mg L-1) + Kinetin (KIN) (1.5 mg L-1) supplementation. Furthermore, BAP (2.0 mg L-1) + KIN (1.5 mg L-1) + gibberellic acid (GA3) (0.5 mg L-1) exhibited better elongation responses with in vitro flowering. Half-strength MS medium with indole-3-butyric acid (IBA) (1.5 mg L-1) exhibited the highest rooting responses and IBA (1.0 mg L-1) with highest fruits, and overall biomass. Higher contents of withaferin A (WFA) [∼8.2 mg g-1 dry weight (DW)] were detected in the reproductive phase, whereas substantially lower WFA contents (∼1.10 mg g-1 DW) were detected in the vegetative phase. Cycloartenol synthase (CAS) (P = 0.0025), sterol methyltransferase (SMT) (P = 0.0059), and 1-deoxy-D-xylulose-5-phosphate reductase (DXR) (P = 0.0375) genes resulted in a significant fold change in expression during the reproductive phase. The liquid chromatography-mass spectrometry (LC-MS) analysis revealed metabolites that were common (177) and distinct in reproductive (218) and vegetative (167) phases. Adventitious roots cultured using varying concentrations of indole-3-acetic acid (IAA) (0.5 mg L-1) + IBA (1.0 mg L-1) + GA3 (0.2 mg L-1) exhibited the highest biomass, and IAA (0.5 mg L-1) + IBA (1.0 mg L-1) exhibited the highest withanolides content. Overall, our findings demonstrate the peculiarity of withanolide biosynthesis during distinct growth phases, which is relevant for the large-scale production of withanolides.

Epigenetic Marks, DNA Damage Markers, or Both? The Impact of Desiccation and Accelerated Aging on Nucleobase Modifications in Plant Genomic DNA

Modifications of DNA nucleobases are present in all forms of life. The purpose of these modifications in eukaryotic cells, however, is not always clear. Although the role of 5-methylcytosine (m⁵C) in epigenetic regulation and the maintenance of stability in plant genomes is becoming better understood, knowledge pertaining to the origin and function of oxidized nucleobases is still scarce. The formation of 5-hydroxymetylcytosine (hm⁵C) in plant genomes is especially debatable. DNA modifications, functioning as regulatory factors or serving as DNA injury markers, may have an effect on DNA structure and the interaction of genomic DNA with proteins. Thus, these modifications can influence plant development and adaptation to environmental stress. Here, for the first time, the changes in DNA global levels of m⁵C, hm⁵C, and 8-oxo-7,8-dihydroguanine (8-oxoG) measured by ELISA have been documented in recalcitrant embryonic axes subjected to desiccation and accelerated aging. We demonstrated that tissue desiccation induces a similar trend in changes in the global level of hm⁵C and 8-oxoG, which may suggest that they both originate from the activity of reactive oxygen species (ROS). Our study supports the premise that m⁵C can serve as a marker of plant tissue viability whereas oxidized nucleobases, although indicating a cellular redox state, cannot.

Chlorin e6 mediated photodynamic therapy triggers resistance through ATM-related DNA damage response in lung cancer cells

OBJECTIVE

Photodynamic therapy (PDT) has emerged as a promising strategy in the treatment of malignant tumors due to its high selectivity, non-toxicity, and non-invasiveness. However, PDT can also induce DNA damage and subsequent repair response, which may reduce the efficacy of PDT. In the present study, we sought to explore the effect of chlorin e6 (Ce6)-mediated PDT on DNA damage and DNA damage response (DDR) in lung cancer cells. In addition, the effect of PDT combined with ATM inhibitor on molecules of DDR and the possibility of improving the efficacy of PDT were further investigated.

MATERIALS AND METHODS

In the in vitro study, lewis cells were submitted to Ce6 treatment (2, 4, 8, 16, 32 μg/mL). To determine the concentration of Ce6, uptake and toxicity of Ce6 mediated PDT were detected using flow cytometry (FACS), Confocal microscopy, and CCK-8. In the subsequent research, 8 μg/mL of Ce6 was the treatment condition for inducing PDT. The different post-irradiation placement times were further grouped under this condition (2, 4, 6, 12 h). Cellular reactive oxygen species (ROS), damage of DNA were measured by DCFH-DA probe, comet assay respectively. Then the expression of p-ATM, p53, and γ-H2A.X proteins related to DNA damage response, was detected by WB. The efficacy of Ce6 induced PDT was also demonstrated by Annexin-V/PI staining as well as the expression of PCNA, cleaved-caspase-3. On this basis, ATM inhibitor was applied to treat lewis cells combined with Ce6 (2, 4 h) to investigate whether the efficacy of PDT induced by Ce6 can be improved after the ATM-related DDR was blocked. The cell viability, apoptosis, and expression of associated proteins were assayed.

RESULTS

At 2-4 h after PDT treatment, ROS was dramatically elevated in lewis cells, DNA double-strand breaks (DDSB) occurred, as well as up-regulation of DDR proteins γ-H2A.X, p-ATM, and p53. At the same time, lewis cells did not undergo significant apoptosis. After ATM inhibition, the DDR was significantly blocked within 2-4 hours after Ce6 induced PDT, along with a pronounced decrease in cell viability followed by a prominent increase of apoptosis.

CONCLUSION

Ce6-mediated PDT generates ROS in a short period time, thus inducing DNA damage, ATM-related DDR as well as promoting resistance of lung cancer cells to PDT. Combining ATM inhibitor with PDT could effectively inhibit the DDR induced by PDT, thereby enhancing the efficacy. This study reveals a new resistance mechanism of PDT and proposes an intervention strategy.

Effects of nonylphenol exposure on histological changes, apoptosis and time-course transcriptome in gills of white shrimp Litopenaeus vannamei

Nonylphenol (NP) is considered as one of the persistent organic pollutants (POPs) in the environment. Pacific white shrimp Litopenaeus vannamei is the predominant species in China, which is frequently affected by environmental pollutants. However, potential toxicity mechanism of NP in shrimp has not been comprehensively studied. To explore the physiological changes and molecular mechanism involved in NP exposure of shrimp, we analyzed histological alterations, apoptosis and transcriptional responses of L.vannamei subjected to NP. Results indicated that significant changes in the histoarchitecture of the gills were observed after NP exposure for 3, 12 and 48 h. Apoptosis was also detected in a time-dependent manner. Numerous differentially expressed genes (DEGs) were obtained at 3 h, 12 h and 48 h after exposure. On the basis of the expression patterns over the time course, these DEGs were classified into 12 clusters. GO and KEGG enrichment analysis of these DEGs was carried out and a dynamic and global view was obtained in shrimp after NP exposure on a transcriptome level. In addition, 15 DEGs involved in immune response, apoptosis, DNA repair, osmoregulation etc. were selected for qRT-PCR validation. The expression patterns of these DEGs kept a well consistent with the high-throughput data at different timepoints, which confirmed the accuracy and reliability of the transcriptome data. All the results demonstrated that NP exposure might lead to impairments of biological functions in gills, alter immune and antioxidant response, compromise DNA repair and anti-apoptosis abilities of shrimp, cause severe histopathological changes and eventually trigger apoptosis. The present study enriched the information on the toxicity mechanism of crustaceans in response to NP exposure.