Antiangiogenic Potential of Microbial Metabolite Elaiophylin for Targeting Tumor Angiogenesis

The active components and potential mechanisms of Wuji Wan in the treatment of ethanol-induced gastric ulcer: An integrated metabolomics, network pharmacology and experimental validation

ETHNOPHARMACOLOGICAL RELEVANCE

Wuji Wan (WJW) is a traditional Chinese medicine formula that can be found in the "Prescriptions of Taiping Benevolent Dispensary" that has been employed in treating gastric discomfort, burning epigastric pain, and gastric reflux for hundreds of years and has shown promise for treating gastric ulcers (GUs). However, the active components and mechanism of action against GUs remain unclear.

AIM OF THE STUDY

The aim of this study was to explore the active components of WJW and elucidate the underlying mechanism involved in treating GUs.

MATERIALS AND METHODS

Initially, cell viability was measured by a cell counting kit 8 (CCK-8) assay to evaluate the efficacy of WJW-containing serum in vitro. The gastric ulcer index, ulcer inhibition rate, hematoxylin and staining (H&E), and periodic acid-Schiff (PAS) staining were used to evaluate the therapeutic effect of WJW in vivo. Subsequently, the levels of inflammatory factors and oxidative stress factors were determined using an enzyme-linked immunosorbent assays (ELISA) on in vitro and in vivo samples. Additionally, UPLC-Q Exactive Plus Orbitrap HRMS was used to analyze the components that were absorbed into the blood of WJW and its metabolites. Network pharmacology and metabolomics were subsequently used to identify the targets and pathways. Real-time quantitative PCR (RT‒qPCR) and Western blotting were used to verify the mRNA and protein levels of the key targets and pathways. Finally, the active components were identified by molecular docking to verify the binding stability of the components and key targets.

RESULTS

WJW-containing serum ameliorated ethanol-induced damage in GES-1 cells and promoted cell healing. WJW-containing serum reduced IL-6, TNF-α, MDA, and LDH levels while increasing IL-10, SOD, and T-AOC levels in the cells. Moreover, WJW treatment resulted in decreased IL-6, TNF-α, and MDA levels and increased IL-10, SOD, PGE2, and NO levels in GUs rats. In addition, eight components of WJW were absorbed into the blood. The network pharmacology results revealed 192 common targets for blood entry components and GUs, and KEGG analysis revealed that apoptosis signaling pathways were the main pathways involved in WJW activity against GUs. Metabolomic screening was used to identify 13 differential metabolites. There were 23 common targets for blood entry components, GUs, and differential metabolites, with the key targets TNF (TNF-α), AKT1, PTGS2 (COX2) and MAPK1. WJW significantly inhibited the expression of Bax, Caspase-9, Caspase-3, cleaved Caspase-9, cleaved Caspase-3, TNF-α, COX2, and p-p44/42 MAPK while promoting the expression of Bcl-2 and p-AKT1. Molecular docking revealed that the active components of WJW for the treatment of GUs are berberine, palmatine, coptisine, evodiamine, rutaecarpine, evocarpine, and paeoniflorin.

CONCLUSIONS

WJW treatment reduces inflammation and oxidative stress injury and inhibits apoptosis signaling pathways. The main active components are berberine, palmatine, coptisine, evodiamine, rutaecarpine, evocarpine, and paeoniflorin. In this paper, we provide a new strategy for exploring the active components of traditional Chinese medicine formulas for the treatment of diseases based on target mechanisms.

Modulation of hypoxia-inducible factor-1 signaling pathways in cancer angiogenesis, invasion, and metastasis by natural compounds: a comprehensive and critical review

Tumor cells employ multiple signaling mediators to escape the hypoxic condition and trigger angiogenesis and metastasis. As a critical orchestrate of tumorigenic conditions, hypoxia-inducible factor-1 (HIF-1) is responsible for stimulating several target genes and dysregulated pathways in tumor invasion and migration. Therefore, targeting HIF-1 pathway and cross-talked mediators seems to be a novel strategy in cancer prevention and treatment. In recent decades, tremendous efforts have been made to develop multi-targeted therapies to modulate several dysregulated pathways in cancer angiogenesis, invasion, and metastasis. In this line, natural compounds have shown a bright future in combating angiogenic and metastatic conditions. Among the natural secondary metabolites, we have evaluated the critical potential of phenolic compounds, terpenes/terpenoids, alkaloids, sulfur compounds, marine- and microbe-derived agents in the attenuation of HIF-1, and interconnected pathways in fighting tumor-associated angiogenesis and invasion. This is the first comprehensive review on natural constituents as potential regulators of HIF-1 and interconnected pathways against cancer angiogenesis and metastasis. This review aims to reshape the previous strategies in cancer prevention and treatment.

Pigmented Microbial Extract (PMB) from Exiguobacterium Species MB2 Strain (PMB1) and Bacillus subtilis Strain MB1 (PMB2) Inhibited Breast Cancer Cells Growth In Vivo and In Vitro

Breast cancer (BC) continues to be one of the major causes of cancer deaths in women. Progress has been made in targeting hormone and growth factor receptor-positive BCs with clinical efficacy and success. However, little progress has been made to develop a clinically viable treatment for the triple-negative BC cases (TNBCs). The current study aims to identify potent agents that can target TNBCs. Extracts from microbial sources have been reported to contain pharmacological agents that can selectively inhibit cancer cell growth. We have screened and identified pigmented microbial extracts (PMBs) that can inhibit BC cell proliferation by targeting legumain (LGMN). LGMN is an oncogenic protein expressed not only in malignant cells but also in tumor microenvironment cells, including tumor-associated macrophages. An LGMN inhibition assay was performed, and microbial extracts were evaluated for in vitro anticancer activity in BC cell lines, angiogenesis assay with chick chorioallantoic membrane (CAM), and tumor xenograft models in Swiss albino mice. We have identified that PMB from the Exiguobacterium (PMB1), inhibits BC growth more potently than PMB2, from the Bacillus subtilis strain. The analysis of PMB1 by GC-MS showed the presence of a variety of fatty acids and fatty-acid derivatives, small molecule phenolics, and aldehydes. PMB1 inhibited the activity of oncogenic legumain in BC cells and induced cell cycle arrest and apoptosis. PMB1 reduced the angiogenesis and inhibited BC cell migration. In mice, intraperitoneal administration of PMB1 retarded the growth of xenografted Ehrlich ascites mammary tumors and mitigated the proliferation of tumor cells in the peritoneal cavity in vivo. In summary, our findings demonstrate the high antitumor potential of PMB1.

Elaiophylin Elicits Robust Anti-Tumor Responses via Apoptosis Induction and Attenuation of Proliferation, Migration, Invasion, and Angiogenesis in Pancreatic Cancer Cells

Pancreatic cancer remains a formidable challenge in oncology due to its aggressive nature and limited treatment options. In this study, we investigate the potential therapeutic efficacy of elaiophylin, a novel compound, in targeting BxPC-3 and PANC-1 pancreatic cancer cells. We comprehensively explore elaiophylin's impact on apoptosis induction, proliferation inhibition, migration suppression, invasion attenuation, and angiogenesis inhibition, key processes contributing to cancer progression and metastasis. The results demonstrate that elaiophylin exerts potent pro-apoptotic effects, inducing a substantial increase in apoptotic cells. Additionally, elaiophylin significantly inhibits proliferation, migration, and invasion of BxPC-3 and PANC-1 cells. Furthermore, elaiophylin exhibits remarkable anti-angiogenic activity, effectively disrupting tube formation in HUVECs. Moreover, elaiophylin significantly inhibits the Wnt/β-Catenin signaling pathway. Our findings collectively demonstrate the multifaceted potential of elaiophylin as a promising therapeutic agent against pancreatic cancer via inhibition of the Wnt/β-Catenin signaling pathway. By targeting diverse cellular processes crucial for cancer progression, elaiophylin emerges as a prospective candidate for future targeted therapies. Further investigation of the in vivo efficacy of elaiophylin is warranted, potentially paving the way for novel and effective treatment approaches in pancreatic cancer management.

A Network Comprised of miR-15b and miR-29a Is Involved in Vascular Endothelial Growth Factor Pathway Regulation in Thymus Adipose Tissue from Elderly Ischemic Cardiomyopathy Subjects

As the human thymus ages, it undergoes a transformation into adipose tissue known as TAT. Interestingly, in previous research, we observed elevated levels of vascular endothelial growth factor A (VEGFA) in TAT from patients with ischemic cardiomyopathy (IC), particularly in those over 70 years old. Moreover, in contrast to subcutaneous adipose tissue (SAT), TAT in elderly individuals exhibits enhanced angiogenic properties and the ability to stimulate tube formation. This makes TAT a promising candidate for angiogenic therapies and the regeneration of ischemic tissues following coronary surgery. MicroRNAs (miRNAs) have emerged as attractive therapeutic targets, especially those that regulate angiogenic processes. The study's purpose is to determine the miRNA network associated with both the VEGFA pathway regulation and the enrichment of age-linked angiogenesis in the TAT. RT-PCR was used to analyze angiogenic miRNAs and the expression levels of their predicted target genes in both TAT and SAT from elderly and middle-aged patients treated with coronary artery bypass graft surgery. miRTargetLink Human was used to search for miRNAs and their target genes. PANTHER was used to annotate the biological processes of the predicted targets. The expression of miR-15b-5p and miR-29a-3p was significantly upregulated in the TAT of elderly compared with middle-aged patients. Interestingly, VEGFA and other angiogenic targets were significantly upregulated in the TAT of elderly patients. Specifically: JAG1, PDGFC, VEGFA, FGF2, KDR, NOTCH2, FOS, PDGFRA, PDGFRB, and RHOB were upregulated, while PIK3CG and WNT7A were downregulated. Our results provide strong evidence of a miRNA/mRNA interaction network linked with age-associated TAT angiogenic enrichment in patients with IC.

Elaiophylin Inhibits Tumorigenesis of Human Lung Adenocarcinoma by Inhibiting Mitophagy via Suppression of SIRT1/Nrf2 Signaling

Lung adenocarcinoma (LADC), the most common type of lung cancer, is still one of the most aggressive and rapidly fatal tumor types, even though achievements in new therapeutic approaches have been developed. Elaiophylin as a C2 symmetrically glycosylated 16 macrolides has been reported to be a late-stage autophagy inhibitor with a potent anti-tumor effect on various cancers. This study investigated the anti-tumor effect of elaiophylin on human LADC for the first time in in vitro and in vivo models. The in vitro study in LADC A549 cells showed that elaiophylin significantly inhibited cell viability and induced cell apoptosis through the suppression of mitophagy and induction of cellular and mitochondrial oxidative stress. Proteomic analysis and molecular docking assay implicated that SIRT1 was likely the direct target of elaiophylin in A549 cells. Further mechanistic study verified that elaiophylin reduced Nrf2 deacetylation, expression, and transcriptional activity as well as cytoplasm translocation by downregulating SIRT1 expression and deacetylase activity. Additionally, SIRT1/Nrf2 activation could attenuate elaiophylin-induced mitophagy inhibition and oxidative stress. The in vivo study in the A549-xenograft mice model showed that the anti-tumor effect of elaiophylin was accompanied by the decreased expressions of SIRT1, Nrf2, Parkin, and PINK1. Thus, the present study reports that elaiophylin has potent anti-tumor properties in LADC, which effect is likely mediated through suppressing the SIRT1/Nrf2 signaling. In conclusion, elaiophylin may be a novel drug candidate for LADC and SIRT1 may be a new therapeutic target for such devastating malignancy.

Assessment of the Potential of Sarcandra glabra (Thunb.) Nakai. in Treating Ethanol-Induced Gastric Ulcer in Rats Based on Metabolomics and Network Analysis

Gastric ulcer (GU) is one of the most commonly diagnosed diseases worldwide, threatening human health and seriously affecting quality of life. Reports have shown that the Chinese herbal medicine Sarcandra glabra (Thunb.) Nakai (SGN) can treat GU. However, its pharmacological effects deserve further validation; in addition, its mechanism of action is unclear. An acute gastric ulcer (AGU) rat model induced by alcohol was used to evaluate the gastroprotective effect of SGN by analysis of the histopathological changes in stomach tissue and related cytokine levels; the potential mechanisms of action of SGN were investigated via serum metabolomics and network pharmacology. Differential metabolites of rat serum were identified by metabolomics and the metabolic pathways of the identified metabolites were enriched via MetaboAnalyst. Furthermore, the critical ingredients and candidate targets of SGN anti-AGU were elucidated. A compound-reaction-enzyme-gene network was established using Cytoscape version 3.8.2 based on integrated analysis of metabolomics and network pharmacology. Finally, molecular docking was applied to verify the acquired key targets. The results showed that SGN exerted a certain gastroprotective effect via multiple pathways and targets. The effects of SGN were mainly caused by the key active ingredients isofraxidin, rosmarinic, and caffeic acid, which regulate hub targets, such as PTGS2, MAPK1, and KDR, which maintain the homeostasis of related metabolites. Signal pathways involved energy metabolism as well as immune and amino acid metabolism. Overall, the multi-omics techniques were proven to be promising tools in illuminating the mechanism of action of SGN in protecting against diseases. This integrated strategy provides a basis for further research and clinical application of SGN.

Elaiophylin Inhibits Tumorigenesis of Human Uveal Melanoma by Suppressing Mitophagy and Inducing Oxidative Stress via Modulating SIRT1/FoxO3a Signaling

Uveal melanoma (UM) is the most common primary intraocular tumor in adults, which is associated with poor prognosis. Up to 50% of UM patients develop metastasis. Therapeutics that have proven effective in cutaneous melanoma have little success in treating UM, possibly due to its low mutational burden. Therefore, new drug therapies are highly desired for UM. Our in vitro studies showed that Elaiophylin, a late-stage autophagy inhibitor, exhibited an outstanding anticancer activity in human UM cell lines and human UM primary cells through suppressing mitophagy, inducing oxidative stress and leading to autophagic cell death. Our mechanistic study revealed that Elaiophylin exerted its effect by down-regulating SIRT1 and thus influencing deacetylation and mitochondrial localization of FoxO3a. In our confirmatory experiments, SRT1720, a SIRT1 specific activator, could attenuate Elaiophylin-induced inhibition of mitophagy and elevation of oxidative stress, and such effects was partly reversed by FoxO3a knockdown. Our further in vivo studies showed that Elaiophylin dramatically inhibited tumor growth in the human UM xenograft mouse model, which was accompanied with a decreased SIRT1 expression. Thus, the current study is the first to demonstrate that Elaiophylin has a potent anti-cancer effect against UM, which activity is possibly mediated through regulating SIRT1-FoxO3a signaling axis. And Elaiophylin may be a new and promising drug candidate to treat human UM.

Microvascular Experimentation in the Chick Chorioallantoic Membrane as a Model for Screening Angiogenic Agents including from Gene-Modified Cells

The chick chorioallantoic membrane (CAM) assay model of angiogenesis has been highlighted as a relatively quick, low cost and effective model for the study of pro-angiogenic and anti-angiogenic factors. The chick CAM is a highly vascularised extraembryonic membrane which functions for gas exchange, nutrient exchange and waste removal for the growing chick embryo. It is beneficial as it can function as a treatment screening tool, which bridges the gap between cell based in vitro studies and in vivo animal experimentation. In this review, we explore the benefits and drawbacks of the CAM assay to study microcirculation, by the investigation of each distinct stage of the CAM assay procedure, including cultivation techniques, treatment applications and methods of determining an angiogenic response using this assay. We detail the angiogenic effect of treatments, including drugs, metabolites, genes and cells used in conjunction with the CAM assay, while also highlighting the testing of genetically modified cells. We also present a detailed exploration of the advantages and limitations of different CAM analysis techniques, including visual assessment, histological and molecular analysis along with vascular casting methods and live blood flow observations.

Elaiophylin Is a Potent Hsp90/ Cdc37 Protein Interface Inhibitor with K-Ras Nanocluster Selectivity

The natural product elaiophylin is a macrodiolide with a broad range of biological activities. However, no direct target of elaiophylin in eukaryotes has been described so far, which hinders a systematic explanation of its astonishing activity range. We recently showed that the related conglobatin A, a protein–protein interface inhibitor of the interaction between the N-terminus of Hsp90 and its cochaperone Cdc37, blocks cancer stem cell properties by selectively inhibiting K-Ras4B but not H-Ras. Here, we elaborated that elaiophylin likewise disrupts the Hsp90/ Cdc37 interaction, without affecting the ATP-pocket of Hsp90. Similarly to conglobatin A, elaiophylin decreased expression levels of the Hsp90 client HIF1α, a transcription factor with various downstream targets, including galectin-3. Galectin-3 is a nanocluster scaffold of K-Ras, which explains the K-Ras selectivity of Hsp90 inhibitors. In agreement with this K-Ras targeting and the potent effect on other Hsp90 clients, we observed with elaiophylin treatment a submicromolar IC₅₀ for MDA-MB-231 and MIA-PaCa-2 3D spheroid formation. Finally, a strong inhibition of MDA-MB-231 cells grown in the chorioallantoic membrane (CAM) microtumor model was determined. These results suggest that several other macrodiolides may have the Hsp90/ Cdc37 interface as a target site.

Therapeutic applications and biological activities of bacterial bioactive extracts

Bacteria are rich in a wide variety of secondary metabolites, such as pigments, alkaloids, antibiotics, and others. These bioactive microbial products serve a great application in human and animal health. Their molecular diversity allows these natural products to possess several therapeutic attributes and biological functions. That's why the current natural drug industry focuses on uncovering all the possible ailments and diseases that could be combated by bacterial extracts and their secondary metabolites. In this paper, we review the major utilizations of bacterial natural products for the treatment of cancer, inflammatory diseases, allergies, autoimmune diseases, infections and other diseases that threaten public health. We also elaborate on the identified biological activities of bacterial secondary metabolites including antibacterial, antifungal, antiviral and antioxidant activities all of which are essential nowadays with the emergence of drug-resistant microbial pathogens. Throughout this review, we discuss the possible mechanisms of actions in which bacterial-derived biologically active molecular entities could possess healing properties to inspire the development of new therapeutic agents in academia and industry.

Novel Nargenicin A1 Analog Inhibits Angiogenesis by Downregulating the Endothelial VEGF/VEGFR2 Signaling and Tumoral HIF-1α/VEGF Pathway

Targeting angiogenesis is an attractive strategy for the treatment of angiogenesis-related diseases, including cancer. We previously identified 23-demethyl 8,13-deoxynargenicin (compound 9) as a novel nargenicin A1 analog with potential anticancer activity. In this study, we investigated the antiangiogenic activity and mode of action of compound 9. This compound was found to effectively inhibit in vitro angiogenic characteristics, including the proliferation, invasion, capillary tube formation, and adhesion of human umbilical vein endothelial cells (HUVECs) stimulated by vascular endothelial growth factor (VEGF). Furthermore, compound 9 suppressed the neovascularization of the chorioallantoic membrane of growing chick embryos in vivo. Notably, the antiangiogenic properties of compound 9 were related to the downregulation of VEGF/VEGFR2-mediated downstream signaling pathways, as well as matrix metalloproteinase (MMP)-2 and MMP-9 expression in HUVECs. In addition, compound 9 was found to decrease the in vitro AGS gastric cancer cell-induced angiogenesis of HUVECs by blocking hypoxia-inducible factor-1α (HIF-1α) and VEGF expression in AGS cells. Collectively, our findings demonstrate for the first time that compound 9 is a promising antiangiogenic agent targeting both VEGF/VEGFR2 signaling in ECs and HIF-1α/VEGF pathway in tumor cells.

Natural Occurrence, Bioactivity and Biosynthesis of Elaiophylin Analogues

Elaiophylins belong to a special family of 16-membered macrodiolides with C₂-symmetry. They have exhibited remarkable biological activities, such as antimicrobial, anthelmintic, anticancer, immunosuppressive, anti-inflammatory, antiviral, and α-glucosidase inhibitory activities. A member of elaiophylins, efomycin M, is as a specific small molecule inhibitor of selectin in preclinical trial for the treatment of psoriasis, ischemia-reperfusion, and allergy. The biosynthetic investigation of elaiophylins has uncovered a unique thioesterase, which is responsible for the formation of C₂-symmetric diolide. We herein summarize the natural occurrence, bioactivity, and biosynthesis of elaiophylins covering the literatures from 1959 to 2019. Hopefully, this review will inspire further research interests of these compounds and encourage the discovery of new analogues by metabolic engineering or genome mining.

Efomycins K and L From a Termite-Associated Streptomyces sp. M56 and Their Putative Biosynthetic Origin

Two new elaiophylin derivatives, efomycins K (1) and L (2), and five known elaiophylin derivatives (3–7) were isolated from the termite-associated Streptomyces sp. M56. The structures were determined by 1D and 2D NMR and HR-ESIMS analyses and comparative CD spectroscopy. The putative gene cluster responsible for the production of the elaiophylin and efomycin derivatives was identified based on significant homology to related clusters. Phylogenetic analysis of gene cluster domains was used to provide a biosynthetic rational for these new derivatives and to demonstrate how a single biosynthetic pathway can produce diverse structures.

S, Balakrishnan A, Katakia YT, Chatterjee S, Nagasundaram N. A marine sponge associated fungal metabolite monacolin X suppresses angiogenesis by down regulating VEGFR2 signaling

Cancer is one of the leading causes of global death and there is an urgent need for the development of cancer treatment; targeting VEGFR2 could be one of the promising therapies. In the present study, previously isolated marine fungal metabolite monacolin X, suppresses in vitro angiogenic characteristics such as proliferation, migration, adhesion, invasion and tube formation of HUVECs when stimulated by VEGF, at a non-toxic concentration. Monacolin X downregulated VEGFR2, PKCα and PKCη mRNA expression. Further, monacolin X inhibited in vivo angiogenesis in CAM assay, vascular sprouting in aortic ring, decreased ISV and SIV length and diameter in Tg (Kdr:EGFP)/ko1 zebrafish embryos. Monacolin X showed reduced protein expression of pVEGFR2, pAKT1, pMAPKAPK2, pFAK and pERK1 in breast cancer lines and in DMBA induced mammary carcinoma in SD rats showed tumor regression and anti-angiogenesis ability via decrease pVEGFR2 and pAKT1 protein expression. In silico studies also revealed monacolin X ability to bind to crucial amino acid Cys 919 in the active site of VEGFR2 suggesting it to be a potent VEGFR2 inhibitor.

Cancer is one of the leading causes of global deaths and there is an urgent need for the development cancer treatment; targeting VEGFR2 could be one of the promising therapies.

Near-Infrared Fluorescent Peptides with High Tumor Selectivity: Novel Probes for Image-Guided Surgical Resection of Orthotopic Glioma

The complete excision of glioblastomas with maximal retention of surrounding normal tissues can have a positive effect on the survival status and quality of life of patients. Near-infrared fluorescence (NIRF) optical imaging of the tumor vasculature offers a noninvasive method for detection of early stage glioblastoma and efficient monitoring of therapeutic responses. The aim of this study was to develop a novel NIRF imaging probe as a visualization tool for image-guided surgical resection of orthotopic glioblastoma. In this study, Cy5.5-RKL, Cy5.5-NKL, and Cy5.5-DKL probes were successfully synthesized, and their properties were investigated in vitro and in vivo. In vivo, Cy5.5-RKL and Cy5.5-NKL were able to detect U87MG xenografts for at least 8 h post injection. The maximum tumor-to-muscle ratios of Cy5.5-RKL and Cy5.5-NKL were 7.65 ± 0.72 and 5.43 ± 0.72, respectively. Of the probes, Cy5.5-RKL displayed the best delineation of the boundaries between orthotopic glioblastomas and normal brain tissue at 8 h p.i. In conclusion, NIRF imaging using Cy5.5-RKL is promising not only for diagnostic purposes but also for use in image-guided surgery for orthotopic glioblastoma or other superficial tumors.

Research Progress of Angiogenesis in Atherosclerotic Plaque in Chinese Medicine and Western Medicine

Angiogenesis in atherosclerotic plaque plays a critical role in the mechanism of atherosclerotic physiopathology. Present consensus shows that angiogenesis in atherosclerotic plaque is mainly resulted in hypoxia, inflammation and some pro-angiogenic factors. The homeostasis in plaque, which is hypoxic and infiltrated by inflammatory cells, may lead to angiogenesis, increase the plaque instability and the incidence rate of vascular events. This article reviews the progression of pathogenetic mechanism, physiopathological significance, relevant detecting technique and corresponding therapeutic methods of Chinese and Western medicine of angiogenesis in atherosclerotic plaque, so as to provide more theoretical basis for atherosclerotic clinical treatment.

Efficacy of inverso isomer of CendR peptide on tumor tissue penetration

The dense extracellular matrix and high interstitial fluid pressure of tumor tissues prevent the ability of anti-tumor agents to penetrate deep into the tumor parenchyma for treatment effects. C-end rule (CendR) peptides can enhance the permeability of tumor blood vessels and tumor tissues via binding to neuropilin-1 (NRP-1), thus aiding in drug delivery. In this study, we selected one of the CendR peptides (sequence RGERPPR) as the parent l-peptide and substituted d-amino acids for the l-amino acids to synthesize its inverso peptide _D(RGERPPR). We investigated the NRP-1 binding activity and tumor-penetrating ability of _D(RGERPPR). We found that the binding affinity of _D(RGERPPR) with NRP-1 and the cellular uptake was significantly higher than that of RGERPPR. Evans Blue tests revealed that _D(RGERPPR) exhibited improved tumor-penetrating ability in C6, U87 and A549 tumor-bearing nude mice. Using nude mice bearing A549 xenograft tumors as a model, we found that the rate of tumor growth in the group co-administered with _D(RGERPPR) and gemcitabine (Gem) was significantly lower than the gemcitabine-treated group with a tumor suppression rate (TSR%) of 55.4%. Together, our results demonstrate that _D(RGERPPR) is a potential tumor-penetrating peptide.