Research progress in tumor angiogenesis and drug resistance in breast cancer

Angiogenesis is considered a hallmark pathophysiological process in tumor development. Aberrant vasculature resulting from tumor angiogenesis plays a critical role in the development of resistance to breast cancer treatments, via exacerbation of tumor hypoxia, decreased effective drug concentrations within tumors, and immune-related mechanisms. Antiangiogenic therapy can counteract these breast cancer resistance factors by promoting tumor vascular normalization. The combination of antiangiogenic therapy with chemotherapy, targeted therapy, or immunotherapy has emerged as a promising approach for overcoming drug resistance in breast cancer. This review examines the mechanisms associated with angiogenesis and the interactions among tumor angiogenesis, the hypoxic tumor microenvironment, drug distribution, and immune mechanisms in breast cancer. Furthermore, this review provides a comprehensive summary of specific antiangiogenic drugs, and relevant studies assessing the reversal of drug resistance in breast cancer. The potential mechanisms underlying these interventions are discussed, and prospects for the clinical application of antiangiogenic therapy to overcome breast cancer treatment resistance are highlighted.

Roles of the tumor microenvironment in the resistance to programmed cell death protein 1 inhibitors in patients with gastric cancer

Despite the continuous developments and advancements in the treatment of gastric cancer(GC),which is one of the most prevalent types of cancer in China,the overall survival is still poor for most patients with advanced GC.In recent years,with the progress in tumor immunology research,attention has shifted toward immunotherapy as a therapeutic approach for GC.Programmed cell death protein 1(PD-1)inhibitors,as novel immunosuppressive medications,have been widely utilized in the treatment of GC.However,many patients are still resistant to PD-1 inhibitors and experience recurrence in the advanced stages of PD-1 immunotherapy.To reduce the occurrence of drug resistance and recurrence in GC patients receiving PD-1 immunotherapy,to maximize the clinical activity of immunosuppressive drugs,and to elicit a lasting immune response,it is essential to research the tumor microenvironment mechanisms leading to PD-1 inhibitor resistance in GC patients.This article reviews the progress in studying the factors influencing the resistance to PD-1 inhibitors in the GC tumor microenvironment,aiming to provide insights and a basis for reducing resistance to PD-1 inhibitors for GC patients in the future.

Erythropoietin-induced hepatocyte receptor A2 regulates effect of pyroptosis on gastrointestinal colorectal cancer occurrence and metastasis resistance

Erythropoietin-induced hepatocyte receptor A2(EphA2)is a receptor tyrosine kinase that plays a key role in the development and progression of a variety of tumors.This article reviews the expression of EphA2 in gastrointestinal(GI)colorectal cancer(CRC)and its regulation of pyroptosis.Pyroptosis is a form of programmed cell death that plays an important role in tumor suppression.Studies have shown that EphA2 regulates pyrodeath through various signaling pathways,affecting the occurrence,development and metastasis of GI CRC.The overexpression of EphA2 is closely related to the aggressiveness and metastasis of GI CRC,and the inhibition of EphA2 can induce pyrodeath and improve the sensitivity of cancer cells to treatment.In addition,EphA2 regulates intercellular communication and the microenvironment through interactions with other cytokines and receptors,further influencing cancer progression.The role of EphA2 in GI CRC and its underlying mechanisms provide us with new perspectives and potential therapeutic targets,which have important implications for future cancer treatment.

Analysis of Pathogen Distribution and Drug Resistance of Nosocomial Infections Accompanied in Patients with Malignant Tumor

Objective： To investigate the pathogen distribution and drug resistance of nosocomial infections accompanied in patients with malignant tumor. Methods： The pathogen culture and drug-sensitivity data of 107 specimens isolated from malignant tumor patients accompanied with nosocomial infection were retrospectively analyzed. Results： Among 118 strains of pathogens isolated from 107 specimens, 77 were gram-negative bacillus（65.3%）, 26 were gram-positive coccus（65.3%）, and 15 were fungus（12.7%）. Eleven specimens were revealed to have combined infection of bacterium and fungus. Gram-negative bacillus showed high sensitivity to amikacin, ciprofloxacin, and tienam. Gram-positive cocci were highly sensitive to tienam and vancomycin. The bacteria were resistant to other antibiotics in different degrees, Vancomycin-resistant staphylococcus was not detected, Candida was sensitive to antifungals. Conclusion： Conditional pathogenic bacteria were mainly responsible for nosocomial infections in malignant tumor patients with considerable drug resistance. This shows that bacterial tests and the rational use of antibiotics should be emphasized in clinical practice to prevent the formation of drug resistant strains and further endogenous infections.

Functional Activity of Circulating Phagocytes as Potential Pretreatment Marker of Tumor Drug Resistance

The aim of this work was a study of the functional activity of neutrophils and peripheral blood monocytes in rats with the transplanted Walker carcinosarcoma as potential predictors of the sensitivity of this tumor to doxorubicin treatment. This study provides an evidence that such indices of the functional activity of circulating phagocytes of the tumor-bearing rats as the quantity and the phagocytosis intensity of monocytes, as well as the intensity of ROS production by monocytes and neutrophils, may reflect the degree of sensitivity of the tumor to doxorubicin. So it was shown that the growth of the resistant tumor caused a significant increase of the number of circulating phagocytic cells and the intensity of phagocytosis by more than 100% (p < 0.001) compared with the corresponding indices of intact rats and rats with the parental variant of the tumor. The ability of blood mono-cytes and neutrophils of rats with a resistant tumor to produce ROS was also significantly different from that in intact rats and animals with the parental carcinosarcoma variant. The predictive value of these indices is especially important in the dynamic monitoring of the development of tumor drug resistance during long-term cancer chemotherapy. Considering the standard 2 - 3 week interval between the courses of cancer therapy and the short lifetime of circulating phagocytes, an assessment of the indices of their functional activity before each subsequent course can be considered as a pretreatment assessment. Meanwhile, further studies are needed to determine the spectrum of malignant neoplasms for which the degree of tumor drug resistance correlates with the functional activity of circulating phagocytes.

Subpopulation cooperation renders drug resistance of hepatobiliary tumor organoids

Hepatobiliary tumors are of high grade of heterogeneity, which is recognized as a key contributor to drug resistance and poor disease prognosis. However, the intrinsic mechanism between heterogeneity and drug response in hepatobiliary tumor is still largely unknown. Using tumor organoid models, Wang and her colleagues have found that cooperation among distinct subpopulations might be a key mechanism for drug resistance in hepatobiliary tumor.

Histone modification as a drug resistance driver in brain tumors

Patients with brain tumors,specifically,malignant forms such as glioblastoma,medulloblastoma and ependymoma,exhibit dismal survival rates despite advances in treatment strategies.Chemotherapeutics,the primary adjuvant treatment for human brain tumors following surgery,commonly lack efficacy due to either intrinsic or acquired drug resistance.New treatments targeting epigenetic factors are being explored.Post-translational histone modification provides a critical regulatory platform for processes such as chromosome condensation and segregation,apoptosis,gene transcription,and DNA replication and repair.This work reviews how aberrant histone modifications and alterations in histone-modifying enzymes can drive the acquisition of drug resistance in brain tumors.Elucidating these mechanisms should lead to new treatments for overcoming drug resistance.

Effects of Taxotere on invasive potential and multidrug resistance phenotype in pancreatic carcinoma cell line SUIT-2

INTRODUCTIONDevelopment of drug-resistance to chemotherapyand subsequent metastasis of tumor are primarilyresponsible for treatment failure and the death fromcancer. There have been many previous studies onthe relationship between expression of multidrugresistance (MDR) phenotype P-glycoprotein (P-gp)and the malignant properties of tumors, but theresults are often conflicting[1-8]. The difference intumor types or MDR phenotype induced by specificagents might account for this discrepancy. Taxotere(TXT), a member of the family of taxanes, hasantitumor activity through its effect of promotingthe polymerization of tubulin[9,10].

Tumor microenvironment involvement in colorectal cancer progression via Wnt/β-catenin pathway:Providing understanding of the complex mechanisms of chemoresistance

Colorectal cancer(CRC)continues to be one of the main causes of death from cancer because patients progress unfavorably due to resistance to current therapies.Dysregulation of the Wnt/β-catenin pathway plays a fundamental role in the genesis and progression of several types of cancer,including CRC.In many subtypes of CRC,hyperactivation of theβ-catenin pathway is associated with mutations of the adenomatous polyposis coli gene.However,it can also be associated with other causes.In recent years,studies of the tumor microenvironment(TME)have demonstrated its importance in the development and progression of CRC.In this tumor nest,several cell types,structures,and biomolecules interact with neoplastic cells to pave the way for the spread of the disease.Cross-communications between tumor cells and the TME are then established primarily through paracrine factors,which trigger the activation of numerous signaling pathways.Crucial advances in the field of oncology have been made in the last decade.This Minireview aims to actualize what is known about the central role of the Wnt/β-catenin pathway in CRC chemoresistance and aggressiveness,focusing on crosscommunication between CRC cells and the TME.Through this analysis,our main objective was to increase the understanding of this complex disease considering a more global context.Since many treatments for advanced CRC fail due to mechanisms involving chemoresistance,the data here exposed and analyzed are of great interest for the development of novel and effective therapies.

Co-delivery of resveratrol and docetaxel via polymeric micelles to improve the treatment of drug-resistant tumors

Co-delivery of anti-cancer drugs is promising to improve the efficacy of cancer treatment.This study was aiming to investigate the potential of concurrent delivery of resveratrol(RES)and docetaxel(DTX)via polymeric nanocarriers to treat breast cancer.To this end,methoxyl poly(ethylene glycol)-poly(D,L-lactide)copolymer(mPEG-PDLA)was prepared and characterized using FTIR and 1H NMR,and their molecular weights were determined by GPC.Isobologram analysis and combination index calculation were performed to find the optimal ratio between RES and DTX to against human breast adenocarcinoma cell line(MCF-7 cells).Subsequently,RES and DTX were loaded in the mPEG-PDLA micelles simultaneously,and the morphology,particle size distribution,in vitro release,pharmacokinetic profiles,as well as cytotoxicity to the MCF-7 cells were characterized.IC50 of RES and DTX in MCF-7 cells were determined to be 23.0μg/ml and 10.4μg/ml,respectively,while a lower IC50 of 4.8μg/ml of the combination of RES and DTX was obtained.The combination of RES and DTX at a ratio of 1:1(w/w)generated stronger synergistic effect than other ratios in the MCF-7 cells.RES and DTX loaded mPEG-PDLA micelles exhibited prolonged release profiles,and enhanced cytotoxicity in vitro against MCF-7 cells.The AUC(0→t)of DTX and RES in mPEG-PDLA micelles after i.v.administration to rats were 3.0-fold and 1.6-fold higher than that of i.v.injections of the individual drugs.These findings indicated that the co-delivery of RES and DTX using mPEG-PDLA micelles could have better treatment of tumors.

Distribution and drug resistance of pathogenic bacteria isolated from cancer hospital in 2013

Objective： To understand distribution and drug resistance of pathogenic bacteria from a specialized cancer hospital in 2013 in order to provide a basis for rational clinical antimicrobial agents. Methods： Pathogenic bacteria identification and drug sensitivity tests were performed with a VITEK 2 compact automatic identification system and data were analyzed using WHONET5.6 software.Results： Of the 1,378 strains tested, 980 were Gram-negative bacilli, accounting for 71.1%, in which Klebsiella pneumonia, Escherichia coli and Pseudomonas aeruginosa were the dominant strains. We found 328 Gram-positive coccus, accounting for 23.8%, in which the amount of Staphylococcus aureus was the highest. We identified 46 fungi, accounting for 4.1%. According to the departmental distribution within the hospital, the surgical departments isolated the major strains, accounting for 49.7%. According to disease types, lung cancer, intestinal cancer and esophagus cancer were the top three, accounting for 20.9%, 17.3% and 14.2%, respectively. No strains were resistant to imipenem, ertapenem or vancomycin.Conclusions： Pathogenic bacteria isolated from the specialized cancer hospital have different resistance rates compared to commonly used antimicrobial agents; therefore antimicrobial agents to reduce the morbidity and mortality of infections should be used.

Anticancer Drug Resistance of HeLa Cells Transfected With Rat Glutathione S-transferase pi Gene

To establish a cytologic expressing system of rat glutathione S-transferase pi (GST-pi) cDNA for detecting the resistance of HeLa cells to anticancer drugs. Methods The assessment was made with various anticancer drugs (adriamycin, mitomycin, cisplatinum and vincristine) that showed different cytotoxicities in transfectant HeLa cells with pSV-GT containing rat GST-pi cDNA (HeLa/pSV-GT) or control pSV-neo (HeLa/pSV-neo). Expression levels of GST-pi mRNA in HeLa/pSV-GT and HeLa/pSV-neo were measured by in situ hybridization using Digoxin-labelled cDNA probe. Results HeLa/pSV-GT expressed significantly high degree of GST-pi mRNA, whereas both HeLa/pSV-neo and HeLa cells had very low expression. Cytotoxicities of HeLa/pSV-GT and HeLa/pSV-neo with 4 anticancer drugs were measured by MTT assay. Drug concentrations for yielding 50% inhibition (IC50) in HeLa/pSV-GT by adriamycin, mitomycin and cisplatinum were 70.13 靏/mL, 10.95 靏/mL and 16.52 靏/mL, respectively. In contrast, IC50 in HeLa/pSV-neo was 10.34 靏/mL, 7.48 靏/mL and 13.70 靏/mL, respectively. The cytotoxicities of vincristine on both HeLa/pSV-GT and HeLa/pSV-neo were not significantly different. Conclusions Our findings suggest that HeLa/pSV-GT containing rat GST-pi cDNA is resistant to some anticancer drugs due to overexpression of GST-pi. Also, HeLa/pSV-GT cell line could serve as a useful cytogenetic model for further research.

Drug resistance and new therapies in colorectal cancer

Colorectal cancer(CRC) is often diagnosed at an advanced stage when tumor cell dissemination has taken place. Chemo-and targeted therapies provide only a limited increase of overall survival for these patients. The major reason for clinical outcome finds its origin in therapy resistance. Escape mechanisms to both chemo-and targeted therapy remain the main culprits. Here, we evaluate major resistant mechanisms and elaborate on potential new therapies. Amongst promising therapies is α-amanitin antibodydrug conjugate targeting hemizygous p53 loss. It becomes clear that a dynamic interaction with the tumor microenvironment exists and that this dictates therapeutic outcome. In addition, CRC displays a limited response to checkpoint inhibitors, as only a minority of patients with microsatellite instable high tumors is susceptible. In this review, we highlight new developments with clinical potentials to augment responses to checkpoint inhibitors.

Systemic therapy in gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs)are the most common type of soft tissue sarcoma in the gastrointestinal tract.Most GISTs have been attributed to activated gain-of-function mutations in either KIT or platelet-derived growth factor receptorα,making these molecular features essential targets for therapeutic interventions.Although surgery is the standard treatment for localized GISTs,patients often experience relapse and disease progression even after surgery.In recent years,targeted therapy has significantly improved the prognosis of patients with advanced GISTs.Imatinib mesylate,a KIT inhibitor,is the first-line treatment for advanced GISTs and has revolutionized the treatment of this disease.However,drug resistance remains a major issue with imatinib treatment,as a significant majority of patients become resistant to imatinib either after initiation or after 2–3 years of treatment.Consequently,novel tyrosine kinase inhibitors such as sunitinib,regorafenib,ripretinib,and avapritinib have been introduced to address drug resistance.Immunotherapy has emerged as a potential approach for the treatment of advanced GISTs.This review comprehensively summarizes the pathogenesis of GISTs and the development of targeted therapies and immunotherapies,provides an overview of the emergence of drug resistance in advanced GISTs,and discusses the challenges and prospects associated with the treatment of GISTs.

EFFECT OF ASCORBIC ACID ON DNA SYNTHESIS,INTRACELLULAR ACCUMULATION OF ADM AND ADM RESISTANCE OF TUMOR CELL LINES

Objective: To determine the effect of ascorbic acid (AA) on DNA synthesis, intracellular accumulation of ADM and ADM resistance of tumor cell lines. Methods: K562, K562/ADM and KB cell lines were used to study the effect of ascorbic acid on DNA synthesis, intracellular accumulation of ADM and ADM resistance by fluid scintillometry, MTT method, spectrofluorophotometry and immunocytochemistry. Results: Results showed that AA was capable of inhibiting DNA synthesis of K562 and K562/ADM in a dosedependence fashion, but not KB cell line, and significantly reducing ADM sensitivity in K562 and KB cell lines, as well as potentiating obviously ADM resistance in K562/ADM cell line. Conclusion: These effects of AA may be closely correlated with significant elevation of intracellular accumulation of ADM in KB cell line, and significant reduction of that in K562 and K562/ADM cell lines but possibly not correlated with the expression of Pglycoprotein.

Mechanism and reversal strategies of immune checkpoint blockers drug resistance

Recent years,the immune checkpoint blockers(ICBs)become more and more important in tumor therapy with the development of tumor immunology and achieved significant clinical effects in various solid tumors.ICBs is a type of tumor immunotherapy method which controls and clears tumor by activating the autoimmune system and restoring the body's normal anti-tumor immune response.However,the resistance of ICBs cannot be ignored and still faces many challenges.The mechanism and the solution of ICBs resistance need to be further research.

Taxotere resistance in SUIT Taxotere resistance in pancreatic carcinoma cell line SUIT 2 and its sublines

AIM: To investigate the specific mechanisms of intrinsic and acquired resistance to taxotere (TXT) in pancreatic adenocarcinoma (PAC). METHODS: MTT assay was used to detect the sensitivity of PAC cell line SUIT-2 and its sublines (S-007, S-013, S-020, S-028 and TXT selected SUIT-2 cell line, S2/TXT) to TXT. Mdr1 (P-gp), multidrug resistance associated protein (MRP), lung resistance protein (LRP) and beta-tubulin isotype gene expressions were detected by RT-PCR. The functionality of P-gp and MRP was tested using their specific blocker verapamil (Ver) and indomethacin (IMC), respectively. The transporter activity of P-gp was also confirmed by Rhodamine 123 accumulation assay. RESULTS: S-020 and S2/TXT were found to be significantly resistant to TXT(19 and 9.5-fold to their parental cell line SUIT-2, respectively). RT-PCR demonstrated strong expression of Mdr1 in these two cell lines, but weaker expression or no expression in other cells lines. MRP and LRP expressions were found in most of these cell lines. The TXT-resistance in S2-020 and S2/TXT could be reversed almost completely by Ver, but not by IMC. Flow cytometry showed that Ver increased the accumulation of Rhodamine-123 in these two cell lines. Compared with S-020 and SUIT-2, the levels of beta-tubulin isotype II, III expressions in S-2/TXT were increased remarkably. CONCLUSION: The both intrinsic and acquired TXT-related drug resistance in these PAC cell lines is mainly mediated by P-gp, but had no relationship to MRP and LRP expressions. The increases of beta-tubulin isotype II, III might be collateral changes that occur when the SUIT-2 cells are treated with TXT.

Overcoming EGFR-TKI resistance by targeting the tumor microenvironment

Targeted therapy has ushered in a new era of precision medicine for non-small cell lung cancer(NSCLC).Currently,epidermal growth factor receptor(EGFR)-tyrosine kinase inhibitors(TKIs)stand as the recommended first-line therapy for advanced NSCLC harboring sensitive EGFR mutations.Nevertheless,most patients inevitably confront the challenge of drug resistance.This phenomenon arises not solely from intrinsic alterations within cancer cells but also from the intricate dynamics of the tumor microenvironment and the complex interactions that occur between cancer cells and their immediate surroundings.This review consolidates the current knowledge regarding EGFR-TKI resistance mechanisms,with a specific emphasis on unraveling the role played by the tumor microenvironment.In addition,the review delineates strategic approaches to surmount TKI resistance,thereby enriching the understanding of the interplay between therapeutic agents and the intricate milieu surrounding cancer cells.

Tumor-Penetrating and Mitochondria-Targeted Drug Delivery Overcomes Doxorubicin Resistance in Lung Cancer

As one of the major challenges in tumor chemotherapy,multidrug resistance typically correlates with the poor drug penetration within tumor tissues and drug efflux by the ATP-driven efflux pumps in tumor cells.Herein,we design a kind of near-infrared(NIR)light-and acidity-activated micellar i PUTDN nanoparticle for mitochondria-targeting doxorubicin(DOX)delivery to combat DOX resistance in small-cell lung cancer.While the PEGylated i PUTDN nanoparticles can keep stealth in blood circulation,NIR irradiation at the tumor region can peel off the PEG shell from the nanoparticles,and the exposed i RGD can facilitate deep tumor penetration of the nanoparticles.After being internalized by DOX-resistant H69AR cells,the poly(β-aminoester)s(PAE)-based nanoparticles can release the triphenylphosphonium(TPP)-conjugated DOX(TDOX)into the cytosol,which can further accumulate in mitochondria with the aid of TPP.Consequently,the mitochondrial membrane potential and ATP content are both reduced in DOX-resistant H69AR cells.The in vivo therapeutic results show that TDOX-loaded nanoparticles with the aid of NIR light irradiation can effectively suppress the DOX-resistant small-cell lung cancer without noticeable adverse effects.

Emerging roles of 3D-culture systems in tackling tumor drug resistance

Drug resistance that affects patients universally is a major challenge in cancer therapy.The development of drug resistance in cancer cells is a multifactor event,and its process involves numerous mechanisms that allow these cells to evade the effect of treatments.As a result,the need to understand the molecular mechanisms underlying cancer drug sensitivity is imperative.Traditional 2D cell culture systems have been utilized to study drug resistance,but they often fail to mimic the 3D milieu and the architecture of real tissues and cell-cell interactions.As a result of this,3D cell culture systems are now considered a comprehensive model to study drug resistance in vitro.Cancer cells exhibit an in vivo behavior when grown in a three-dimensional environment and react to therapy more physiologically.In this review,we discuss the relevance of main 3D culture systems in the study of potential approaches to overcome drug resistance and in the identification of personalized drug targets with the aim of developing patient-specific treatment strategies that can be put in place when resistance emerges.