1.Eupatilin Inhibits Proliferation, Invasion, and Metastasis of Non-small Cell Lung Cancer via EZH2/H3K27me3 Signaling Pathway
Bo XU ; Yihan YU ; Linling HU ; Bo JIANG ; Yu QI ; Shasha YUAN ; Yiling FAN ; Jixian ZHANG ; Qing MIAO
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):58-69
ObjectiveTo investigate the mechanisms by which eupatilin (Eup) inhibits proliferation, invasion, and metastasis of non-small cell lung cancer (NSCLC) through the enhancer of zeste homolog 2/histone H3 lysine 27 trimethylation (EZH2/H3K27me3) signaling pathway. MethodsIn vivo, a subcutaneous xenograft tumor model was established in nude mice using H1299 cells to evaluate the anti-NSCLC effects of Eup. Immunohistochemistry (IHC-P) was used to detect the expression of proliferation- and invasion/metastasis-related proteins, including proliferating cell nuclear antigen (PCNA), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and vascular endothelial growth factor A (VEGFA). In vitro, cell counting kit-8 (CCK-8) assays were performed to determine the viability of H1299 cells treated with different concentrations of Eup (0-200 μmol·L-1) and to select appropriate concentrations. Colony formation and 5-ethynyl-2′-deoxyuridine (EdU) assays were used to evaluate cell proliferation. Wound healing and invasion assays were conducted to assess cell migration and invasion. Human umbilical vein endothelial cell (HUVEC) angiogenesis assays were used to evaluate the effects of Eup on angiogenesis. Transcriptomic analysis was performed to identify the targets of Eup in H1299 cells and to explore its major functions. Molecular docking and molecular dynamics simulations were conducted to predict the binding affinity and interaction stability between Eup and its target proteins. Western blot was used to detect the effects of Eup on the expression levels of EZH2/H3K27me3 pathway-related proteins and proliferation- and invasion/metastasis-related proteins, including PCNA, MMP-2, MMP-9, and VEGFA. ResultsIn the subcutaneous xenograft model, compared with the model group, Eup treatment dose-dependently inhibited the growth of H1299 xenograft tumors, and the tumor inhibition rate was significantly increased (P<0.05). IHC-P results showed that, compared with the model group, high-dose Eup significantly reduced the expression levels of PCNA, MMP-2, MMP-9, and VEGFA in vivo (P<0.05). In vitro, compared with the control group, Eup inhibited the proliferation, invasion, and metastasis of NSCLC cells in a concentration-dependent manner. Transcriptomic analysis further showed that, compared with the control group, Eup significantly downregulated EZH2 expression, and its functional effects were associated with inhibition of tumor metastasis. Molecular docking and molecular dynamics simulations indicated that Eup exhibited strong binding affinity with EZH2 and stable interactions. Western blot results demonstrated that, compared with the model group, Eup significantly inhibited, in a dose-dependent manner, the expression levels of EZH2, H3K27me3, and proliferation- and invasion/metastasis-related proteins (PCNA, MMP-2, MMP-9, and VEGFA) in both in vivo and in vitro experiments (P<0.05). In vitro, compared with the control group, overexpression of EZH2 via plasmid transfection partially reversed the inhibitory effects of Eup on the expression of key proteins involved in proliferation and invasion/metastasis in H1299 cells. ConclusionEup effectively inhibits the proliferation, migration, and invasion of H1299 cells both in vivo and in vitro. The underlying mechanism may be related to inhibition of the EZH2/H3K27me3 signaling pathway and downregulation of proliferation- and invasion/metastasis-related proteins, including PCNA, MMP-2, MMP-9, and VEGFA. Eup may serve as a potential therapeutic agent for suppressing proliferation and invasion/metastasis in NSCLC.
2.Anti-lung Cancer Mechanisms of Yang-warming Herbs and Formulas: A Review
Bo XU ; Yu QI ; Jixian ZHANG ; Linling HU ; Bo JIANG ; Yilong ZOU ; Cunyu FAN ; Yiling FAN ; Qing MIAO ; Yihan YU
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):70-79
Lung cancer, particularly non-small cell lung cancer (NSCLC), is the malignant tumor with the highest incidence and mortality in China and worldwide. In 2022, the global number of deaths reached 1.8 million, accounting for 18.7% of all cancer-related deaths, seriously threatening human health and life, and posing a severe challenge for prevention and treatment. Although treatment strategies for lung cancer have been continuously enriched in recent years, and progress has been made in targeted therapy and immunotherapy, long-term survival benefits remain limited due to primary or acquired drug resistance, low immune responsiveness, and chemotherapy-related toxicities. Therefore, there is an urgent need to explore safe and effective adjunctive therapeutic strategies. Traditional Chinese medicine (TCM), with its advantages of holistic regulation and individualized syndrome differentiation, has played an increasingly prominent role in comprehensive cancer treatment. TCM holds that "Yang deficiency leads to accumulation" is a key pathogenesis of tumors. Based on the theory that "Yang transforms Qi, while Yin forms substance", deficiency of Yang Qi results in impaired warming and transformation functions, leading to internal accumulation of Yin-cold. This is closely related to dysregulation of the immune microenvironment, "cold tumor" characteristics, and dysfunction of the neuroendocrine system in modern medicine. Accordingly, the therapeutic strategy of "warming Yang, supporting healthy Qi, and combating cancer" has gained increasing attention. In recent years, commonly used Yang-warming Chinese herbs, including Aconiti Lateralis Radix Praeparata, Zingiberis Rhizoma, Cinnamomi Cortex, Epimedii Folium, and Psoraleae Fructus, as well as their active constituents, have achieved notable progress in anti-lung cancer research by regulating multiple signaling pathways, inducing apoptosis, inhibiting metastasis, and reversing drug resistance. In addition, Yang-warming formulae such as Sini Tang and Yanghe Tang have shown promising effects in alleviating myelosuppression, improving cancer-related fatigue, managing malignant pleural effusion, and relieving cancer pain. These therapies exhibit toxicity-reducing and efficacy-enhancing effects, significantly improving patients' quality of life and survival benefits. To systematically summarize the roles and mechanisms of Yang-warming Chinese herbal medicines and compound formulae in lung cancer, this paper provides a comprehensive review of recent advances, aiming to offer insights for the clinical practice of TCM in the prevention and treatment of lung cancer.
3.Eupatilin Inhibits Proliferation, Invasion, and Metastasis of Non-small Cell Lung Cancer via EZH2/H3K27me3 Signaling Pathway
Bo XU ; Yihan YU ; Linling HU ; Bo JIANG ; Yu QI ; Shasha YUAN ; Yiling FAN ; Jixian ZHANG ; Qing MIAO
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):58-69
ObjectiveTo investigate the mechanisms by which eupatilin (Eup) inhibits proliferation, invasion, and metastasis of non-small cell lung cancer (NSCLC) through the enhancer of zeste homolog 2/histone H3 lysine 27 trimethylation (EZH2/H3K27me3) signaling pathway. MethodsIn vivo, a subcutaneous xenograft tumor model was established in nude mice using H1299 cells to evaluate the anti-NSCLC effects of Eup. Immunohistochemistry (IHC-P) was used to detect the expression of proliferation- and invasion/metastasis-related proteins, including proliferating cell nuclear antigen (PCNA), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and vascular endothelial growth factor A (VEGFA). In vitro, cell counting kit-8 (CCK-8) assays were performed to determine the viability of H1299 cells treated with different concentrations of Eup (0-200 μmol·L-1) and to select appropriate concentrations. Colony formation and 5-ethynyl-2′-deoxyuridine (EdU) assays were used to evaluate cell proliferation. Wound healing and invasion assays were conducted to assess cell migration and invasion. Human umbilical vein endothelial cell (HUVEC) angiogenesis assays were used to evaluate the effects of Eup on angiogenesis. Transcriptomic analysis was performed to identify the targets of Eup in H1299 cells and to explore its major functions. Molecular docking and molecular dynamics simulations were conducted to predict the binding affinity and interaction stability between Eup and its target proteins. Western blot was used to detect the effects of Eup on the expression levels of EZH2/H3K27me3 pathway-related proteins and proliferation- and invasion/metastasis-related proteins, including PCNA, MMP-2, MMP-9, and VEGFA. ResultsIn the subcutaneous xenograft model, compared with the model group, Eup treatment dose-dependently inhibited the growth of H1299 xenograft tumors, and the tumor inhibition rate was significantly increased (P<0.05). IHC-P results showed that, compared with the model group, high-dose Eup significantly reduced the expression levels of PCNA, MMP-2, MMP-9, and VEGFA in vivo (P<0.05). In vitro, compared with the control group, Eup inhibited the proliferation, invasion, and metastasis of NSCLC cells in a concentration-dependent manner. Transcriptomic analysis further showed that, compared with the control group, Eup significantly downregulated EZH2 expression, and its functional effects were associated with inhibition of tumor metastasis. Molecular docking and molecular dynamics simulations indicated that Eup exhibited strong binding affinity with EZH2 and stable interactions. Western blot results demonstrated that, compared with the model group, Eup significantly inhibited, in a dose-dependent manner, the expression levels of EZH2, H3K27me3, and proliferation- and invasion/metastasis-related proteins (PCNA, MMP-2, MMP-9, and VEGFA) in both in vivo and in vitro experiments (P<0.05). In vitro, compared with the control group, overexpression of EZH2 via plasmid transfection partially reversed the inhibitory effects of Eup on the expression of key proteins involved in proliferation and invasion/metastasis in H1299 cells. ConclusionEup effectively inhibits the proliferation, migration, and invasion of H1299 cells both in vivo and in vitro. The underlying mechanism may be related to inhibition of the EZH2/H3K27me3 signaling pathway and downregulation of proliferation- and invasion/metastasis-related proteins, including PCNA, MMP-2, MMP-9, and VEGFA. Eup may serve as a potential therapeutic agent for suppressing proliferation and invasion/metastasis in NSCLC.
4.Anti-lung Cancer Mechanisms of Yang-warming Herbs and Formulas: A Review
Bo XU ; Yu QI ; Jixian ZHANG ; Linling HU ; Bo JIANG ; Yilong ZOU ; Cunyu FAN ; Yiling FAN ; Qing MIAO ; Yihan YU
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(10):70-79
Lung cancer, particularly non-small cell lung cancer (NSCLC), is the malignant tumor with the highest incidence and mortality in China and worldwide. In 2022, the global number of deaths reached 1.8 million, accounting for 18.7% of all cancer-related deaths, seriously threatening human health and life, and posing a severe challenge for prevention and treatment. Although treatment strategies for lung cancer have been continuously enriched in recent years, and progress has been made in targeted therapy and immunotherapy, long-term survival benefits remain limited due to primary or acquired drug resistance, low immune responsiveness, and chemotherapy-related toxicities. Therefore, there is an urgent need to explore safe and effective adjunctive therapeutic strategies. Traditional Chinese medicine (TCM), with its advantages of holistic regulation and individualized syndrome differentiation, has played an increasingly prominent role in comprehensive cancer treatment. TCM holds that "Yang deficiency leads to accumulation" is a key pathogenesis of tumors. Based on the theory that "Yang transforms Qi, while Yin forms substance", deficiency of Yang Qi results in impaired warming and transformation functions, leading to internal accumulation of Yin-cold. This is closely related to dysregulation of the immune microenvironment, "cold tumor" characteristics, and dysfunction of the neuroendocrine system in modern medicine. Accordingly, the therapeutic strategy of "warming Yang, supporting healthy Qi, and combating cancer" has gained increasing attention. In recent years, commonly used Yang-warming Chinese herbs, including Aconiti Lateralis Radix Praeparata, Zingiberis Rhizoma, Cinnamomi Cortex, Epimedii Folium, and Psoraleae Fructus, as well as their active constituents, have achieved notable progress in anti-lung cancer research by regulating multiple signaling pathways, inducing apoptosis, inhibiting metastasis, and reversing drug resistance. In addition, Yang-warming formulae such as Sini Tang and Yanghe Tang have shown promising effects in alleviating myelosuppression, improving cancer-related fatigue, managing malignant pleural effusion, and relieving cancer pain. These therapies exhibit toxicity-reducing and efficacy-enhancing effects, significantly improving patients' quality of life and survival benefits. To systematically summarize the roles and mechanisms of Yang-warming Chinese herbal medicines and compound formulae in lung cancer, this paper provides a comprehensive review of recent advances, aiming to offer insights for the clinical practice of TCM in the prevention and treatment of lung cancer.
5.Analysis of Toxicity Characteristics and Rational Drug Use of Polygoni Multiflori Radix
Qiongyi FU ; Yupu QI ; Yu HUAN ; Yagang SONG ; Xiangxiang WU ; Mingsan MIAO
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(3):222-231
ObjectivePolygoni Multiflori Radix is a commonly used tonic traditional Chinese medicine (TCM) in clinical practice, but liver injury has often been reported in recent years. Some related preparations containing Polygoni Multiflori Radix have been reported by the National Medical Products Administration many times for the risk of liver injury. This has caused extensive discussion on the potential toxicity of TCM in China and abroad, which has limited the clinical use of Polygoni Multiflori Radix to some extent. To understand the adverse reactions of Polygoni Multiflori Radix, the safe and rational use of Polygoni Multiflori Radix in clinical practice was discussed. MethodsThe pharmacovigilance thought of modern Chinese medicine and the TCM pharmacovigilance system framework of ''identification of poison, use of poison, anti-poison, and detoxification'' were employed to mine the relevant toxicity records, usage and dosage, processing compatibility, and contraindication of taking Polygoni Multiflori Radix in ancient books. The drug safety information of Polygoni Multiflori Radix was summarized by comparing with modern reports. ResultsA total of 74 ancient books related to Polygoni Multiflori Radix were included, suggesting that the toxicity of Polygoni Multiflori Radix was recognized in ancient times. The main chemical components of Polygoni Multiflori Radix had both efficacy and toxicity, and the adverse reactions may be related to long-term use, excessive use, and individual differences. The results showed that the toxic components of Polygoni Multiflori Radix could be reduced by peeling, steaming with black beans, and processing without iron tools. The toxic effects of Polygoni Multiflori Radix could be reduced by the compatibility of Polygoni Multiflori Radix with Poria, Psoraleae Fructus, and Cistanches Herba. ConclusionReasonable dosage, standard processing, correct compatibility, and syndrome differentiation are the key points to standardize the use of Polygoni Multiflori Radix and reduce the incidence of adverse reactions. Clinically, the toxicity classification of TCM should be strengthened, and the susceptible population should be prioritized. The detection indicators and early warning mechanisms should be improved, and precise drug dosage and course of treatment should be guaranteed. These measures can ensure the safe use of Polygoni Multiflori Radix.
6.Analysis of Toxicity Characteristics and Rational Drug Use of Polygoni Multiflori Radix
Qiongyi FU ; Yupu QI ; Yu HUAN ; Yagang SONG ; Xiangxiang WU ; Mingsan MIAO
Chinese Journal of Experimental Traditional Medical Formulae 2026;32(3):222-231
ObjectivePolygoni Multiflori Radix is a commonly used tonic traditional Chinese medicine (TCM) in clinical practice, but liver injury has often been reported in recent years. Some related preparations containing Polygoni Multiflori Radix have been reported by the National Medical Products Administration many times for the risk of liver injury. This has caused extensive discussion on the potential toxicity of TCM in China and abroad, which has limited the clinical use of Polygoni Multiflori Radix to some extent. To understand the adverse reactions of Polygoni Multiflori Radix, the safe and rational use of Polygoni Multiflori Radix in clinical practice was discussed. MethodsThe pharmacovigilance thought of modern Chinese medicine and the TCM pharmacovigilance system framework of ''identification of poison, use of poison, anti-poison, and detoxification'' were employed to mine the relevant toxicity records, usage and dosage, processing compatibility, and contraindication of taking Polygoni Multiflori Radix in ancient books. The drug safety information of Polygoni Multiflori Radix was summarized by comparing with modern reports. ResultsA total of 74 ancient books related to Polygoni Multiflori Radix were included, suggesting that the toxicity of Polygoni Multiflori Radix was recognized in ancient times. The main chemical components of Polygoni Multiflori Radix had both efficacy and toxicity, and the adverse reactions may be related to long-term use, excessive use, and individual differences. The results showed that the toxic components of Polygoni Multiflori Radix could be reduced by peeling, steaming with black beans, and processing without iron tools. The toxic effects of Polygoni Multiflori Radix could be reduced by the compatibility of Polygoni Multiflori Radix with Poria, Psoraleae Fructus, and Cistanches Herba. ConclusionReasonable dosage, standard processing, correct compatibility, and syndrome differentiation are the key points to standardize the use of Polygoni Multiflori Radix and reduce the incidence of adverse reactions. Clinically, the toxicity classification of TCM should be strengthened, and the susceptible population should be prioritized. The detection indicators and early warning mechanisms should be improved, and precise drug dosage and course of treatment should be guaranteed. These measures can ensure the safe use of Polygoni Multiflori Radix.
7.Monte Carlo simulation study of the effect of filter on radiotherapy dosimetry in superficial X-ray therapy apparatus
Li TAO ; Hui ZHANG ; Yikai WU ; Junyi LIU ; Miao QI ; Ning GAO ; Yankui CHANG ; Xi PEI ; Zhi CHEN ; Xie XU
Chinese Journal of Radiological Medicine and Protection 2025;45(3):194-201
Objective:To explore the dosimetry optimization strategy based on filter thickness and shape selection for the bulb superficial X-ray radiotherapy unit.Methods:Monte Carlo code TOPAS was used to model tubular equipment, and the dose distribution from six X-ray energies (50-150 kV) and five conventional aluminum filters (0.5-3.0 mm) with different thickness were simulated in the water model. The percentage depth dose (PDD) curve along the central axis, the center-axis profile dose at different depths, and the lateral dose distribution were analyzed. The dose distribution of three different designs of aluminum filters (conventional cylindrical, conical and oblique cylindrical filters) was compared to evaluate the effect of dosimetric optimization of different filter shapes.Results:Under the same energy, increasing the thickness of the filter can optimize the superficial skin dose, and the optimization effect of depth dose uniformity can be increased by 26% at a depth of 5.5 mm at 70 kV energy. The raised, flat and inclined dose distribution modes can be achieved by using conventional cylindrical, conical and inclined aluminum filters.Conclusions:By selecting the appropriate X-ray energy and filter thickness, an ideal dose distribution matching the tumor depth can be achieved. The application of personalized filters is also of great significance for diverse target areas.
8.Treatment plan optimization for intensity-modulated brachytherapy based on the conjugate gradient algorithm
Miao QI ; Junyi LIU ; Shijun LI ; Yankui CHANG ; Jieping ZHOU ; Bing YAN ; Yong CHENG ; Aidong WU ; Xi PEI ; Xie XU
Chinese Journal of Radiological Medicine and Protection 2025;45(1):56-62
Objective:To investigate the application of the conjugate gradient (CG) algorithm to treatment plan optimization for intensity-modulated brachytherapy (IMBT).Methods:The general Monte Carlo software TOPAS was utilized to simulate the 192Ir source of IMBT, and the unit dose contribution matrix was calculated. An objective function was established using the weighted least squares method and was solved using the CG algorithm to achieve optimized IMBT treatment plans. The optimization was validated using five clinical cervical cancer cases under modulation width 60°. The dose distributions of IMBT treatment plans under 45°, 60°, 90°, 120°, and 180° modulation widths were compared using the Wilcoxon test to determine the optimal IMBT treatment plan for cervical cancer treatment. Results:The CG algorithm successfully optimized IMBT treatment plans under modulation width 60° for five cases within 22.2 s on average. On the premise of sufficient target dose coverage, the average D2 cm 3 values of the bladder and rectum in IMBT treatment plans were 3.66 and 1.97 Gy, respectively, representing reductions of 0.54 and 0.69 Gy compared to traditional brachytherapy plans. For the five modulation widths, the D90% values of all IMBT treatment plans reached 6 Gy, without statistically significant differences ( P > 0.05). The average D2 cm 3 values of the bladder in IMBT treatment plans were significantly lower than those in the traditional brachytherapy plans( P<0.05), with modulation width 60° associated with the greatest reduction of 0.61 Gy. In contrast, the average D2 cm 3 values of the rectum under 45°, 60°, and 90° modulation widths decreased by 0.63, 0.54, and 0.45 Gy, respectively, compared to traditional plans, with statistically significant differences( P<0.05). Conclusions:The CG method enables rapid achievement of optimized IMBT treatment plans that meet clinical requirements, and modulation width 60° contributes to valid dosimetric optimization. This study can serve as a guide for the clinical implementation of IMBT.
9.Textual Research and Application of Famous Classical Formula Huopo Xialingtang
Miao YU ; Huikang ZHANG ; Xiaofan QI ; Fuping LI ; Jichun ZHOU
Chinese Journal of Experimental Traditional Medical Formulae 2025;31(3):192-200
Huopo Xialingtang is a famous classical formula for treating dampness and warmth, which is included in the Catalogue of Ancient Famous Classical Formulas(The First Batch). In this paper, bibliometric methods was used to collect the literature related to Huopo Xialingtang, and 16 items of related literature were retrieved, involving five medical books, which were used to textual research on the origin, name, composition, drug dosage, preparation method, processing and main treatment symptoms of this formula. The results indicated that Huopo Xialingtang was originated from Yiyuan written by Shi Funan in the Qing dynasty, and and was later named and extended by He Lianchen. The composition of the proposed formula was consistent with the record of Yiyuan, and the origin of each Chinese materia medica was basically clear. Houpo was the dried bark and root bark of Magnolia officinalis, Zexie was the dried tubers of Alisma orientale, Kuxingren was the dried mature seeds of Prunus armeniaca, Doukou was the dried mature fruits of Amomum kravanh, the origin of Tuhuoxiang was consistent with the 2018 edition of Shanghai Standards of Processing Chinese Crud Drugs, and the origins of the remaining Chinese medicines were consistent with the 2020 edition of Chinese Pharmacopoeia. The converted dose of each Chinese medicine was 7.46 g for Agastache rugosa, 3.73 g for Magnoliae Officinalis Cortex, 8.39 g for Pinelliae Rhizoma Praeparatum cum Zingibere et Alumine, 11.19 g for Poria, 11.19 g for Armeniacae Semen Amarum, 14.92 g for Coicis Semen, 2.61 g for Amomi Fructus Rotundus, 5.60 g for Polyporus, 5.60 g for Alismatis Rhizoma, 14.92 g for Tetrapanacis Medulla. Huopo Xialingtang was initially used for the treatment of dampness and warmth at the beginning of the disease, and was later expanded to treat dampness obstruction, dampness-warming dysentery and so on, but always with the dampness-heat in the lungs and spleen as the pathogenesis. In modern times, the clinical application is more extensive, used in digestive, respiratory, endocrine, nervous system and other types of diseases, especially for chronic gastritis, stomach pain and fever. By combing the ancient literature of Huopo Xialingtang, we verified the origin of the formula and determined the key information of the prescription, which can provide literature reference for the clinical application and drug development of this formula.
10.Studies on the Design and Activity of Anticancer Peptides Based on the Weak Acidic Microenvironment of Tumors
Yue-Qi NIE ; Miao JIANG ; Hui-Yan WU ; Chang-Hao DING ; Wei REN ; Jun-Yi CHANG ; Ke CHEN ; Shao-Long DU ; Peng ZHANG ; Zhong-Hua LIU
Chinese Journal of Biochemistry and Molecular Biology 2025;41(10):1380-1391
Lung cancer poses a serious threat to global public health security.Chemotherapy,as the main strategy for cancer treatment,faces challenges such as high toxicity and drug resistance.Anticancer peptides have the potential of being developed into new anticancer drugs due to their advantages of broad-spectrum anticancer activity,rapid action,and difficulty in generating drug resistance,but they also face shortcomings such as weak activity and strong toxic side effects.The weakly acidic microenvironment of tumors(pH 6.5-6.8)provides a good idea for the design of anticancer peptides of high-efficiency and low-toxicity.Previously,we designed the acid-sensitive antibacterial peptide pHly-1 using the wolf spider(Lycosa singoriensis)toxin Lycosin-Ⅰ as a template.In this study,we found that pHly-1 also had acid-sensitive anticancer activity.Further alanine scanning analysis of pHly-1 was carried out,and we ob-tained a mutant pHTP-2 with better acid sensitivity,whose IC50(half maximal inhibitory concentration)against A549 cells was 15.68 μmol/L at pH 6.6 and was greater than 100 μmol/L at pH 7.4.At pH 6.6,pHTP-2 could act on various lung cancer cell lines and induce the death of A549 cells by rapid ly-sis;at pH 7.4,500 μmol/L pHTP-2 had weak toxicity to red blood cells(the hemolysis rate was ap-proximately 38%)and primary myocardial cells(the inhibition rate was 49.7%,with P<0.05).Analy-sis of its charge,particle size,morphology,and secondary structure showed that at pH 6.6,the histidine in the sequence of pHTP-2 was protonated,increasing the positive charge(P<0.01),decreasing the hy-drated particle size(P<0.05)and forming an α-helical structure to induce membrane lysis of A549 cells.At pH 7.4,it was deprotonated,the positive charge decreases,a β-sheet structure was formed and self-aggregation occurred,limiting its effect on the A549 cell membrane and showing weak activity.In summary,pHTP-2 could respond to the weakly acidic microenvironment of tumors to exert selective cyto-toxic activity,effectively overcoming the shortcomings of anticancer peptides such as low efficiency and high toxicity.Our findings suggest that it is a high-quality lead molecule for anticancer drugs.

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