All-Trans Retinoic Acid and Doxorubicin Delivery by Folic Acid Modified Polymeric Micelles for the Modulation of Pin1-Mediated DOX-Induced Breast Cancer Stemness and Metastasis

Advances in nanoplatform-based multimodal combination therapy activating STING pathway for enhanced anti-tumor immunotherapy

Activation of the cyclic GMP-AMP synthase(cGAS)-stimulator of interferon genes (STING) has great potential to promote antitumor immunity. As a major effector of the cell to sense and respond to the aberrant presence of cytoplasmic double-stranded DNA (dsDNA), inducing the expression and secretion of type I interferons (IFN) and STING, cGAS-STING signaling pathway establishes an effective natural immune response, which is one of the fundamental mechanisms of host defense in organisms. In addition to the release of heterologous DNA due to pathogen invasion and replication, mitochondrial damage and massive cell death can also cause abnormal leakage of the body's own dsDNA, which is then recognized by the DNA receptor cGAS and activates the cGAS-STING signaling pathway. However, small molecule STING agonists suffer from rapid excretion, low bioavailability, non-specificity and adverse effects, which limits their therapeutic efficacy and in vivo application. Various types of nano-delivery systems, on the other hand, make use of the different unique structures and surface modifications of nanoparticles to circumvent the defects of small molecule STING agonists such as fast metabolism and low bioavailability. Also, the nanoparticles are precisely directed to the focal site, with their own appropriate particle size combined with the characteristics of passive or active targeting. Herein, combined with the cGAS-STING pathway to activate the immune system and kill tumor tissues directly or indirectly, which help maximize the use of the functions of chemotherapy, photothermal therapy(PTT), chemodynamic therapy(CDT), and radiotherapy(RT). In this review, we will discuss the mechanism of action of the cGAS-STING pathway and introduce nanoparticle-mediated tumor combination therapy based on the STING pathway. Collectively, the effective multimodal nanoplatform, which can activate cGAS-STING pathway for enhanced anti-tumor immunotherapy, has promising avenue clinical applications for cancer treatment.

Hypoxia-Responsive Polymersomes for Stemness Reduction in Patient-Derived Solid Tumor Spheroids

Aggressive solid tumors are associated with rapid growth, early hypoxia, a lack of targeted therapies, and a poor prognosis. The hypoxic niches within the rapidly growing solid tumors give rise to a stem-cell-like phenotype with higher metastasis and drug resistance. To overcome the drug resistance of these regions, we used hypoxia-responsive polymersomes with an encapsulated anticancer drug (doxorubicin, Dox) and a stemness modulator (all-trans retinoic acid, ATRA). Reductase enzymes overexpressed in hypoxia reduce the azobenzene linker of the polymers, disrupt the bilayer structure of the polymersomes, and release the encapsulated drugs. We used triple-negative breast cancer (TNBC) as a representative of aggressive and hypoxic solid tumors. We observed that ATRA synergistically enhanced the efficacy of Dox in killing cancer cells. A synergistic combination of the two drug-encapsulated polymersomes reduced the volumes of patient-derived TNBC spheroids by 90%. In contrast, Dox alone decreased the spheroid volumes by 70% and encapsulated ATRA by 19%. Mechanistic studies revealed that ATRA inhibited efflux pumps, leading to a higher concentration of doxorubicin within TNBC cells. In addition, the combination of encapsulated Dox and ATRA significantly decreased stemness expression of the TNBC cells in hypoxia compared to that of Dox alone.

Combating Methotrexate Resistance in Cancer Treatment: A Review on Navigating Pathways and Enhancing Its Efficacy With Fat-Soluble Vitamins

Methotrexate (MTX), a potent analogue and antagonist of folic acid, is a first-line treatment for rheumatoid arthritis, IBD and cancer. The development of MTX resistance contributes to the reduced efficacy and development of adverse reactions, forcing clinicians to withdraw treatment early. This drawback requires combinational approaches to combat the resistance and enhance the efficacy and safety of MTX. To provide a brief overview of MTX resistance and strategies to mitigate its aftereffects in cancer therapy, a literature-based search was conducted using keywords such as cancer pathology, MTX mechanism and resistance, S100A4, folate uptake, folate efflux, P-glycoprotein, beta-catenin and anticancer properties of Vitamins A, D, E and K. Investigations encompassing in vitro studies, in vivo studies and clinical trials were reviewed to identify the mechanisms of resistance induced by MTX and the potential benefits of coadministering fat-soluble vitamins with existing anticancer drugs. Derivates of Vitamin A could target cancer stem cells and increase chemotherapy sensitivity in non-small cell lung cancer. Similarly, calcitriol and cytotoxic medications exhibit additive or synergistic effects. Existing research revealed that fat-soluble vitamins can inhibit drug transporters, such as P-glycoprotein, which inhibit drug efflux, improving chemotherapy efficacy in cancer. As personalised medicine continues to evolve, incorporating combination approaches with MTX and fat-soluble vitamins holds promise for enhancing treatment efficacy, which can counteract MTX resistance via multiple pathways and improve the safety profile.

Innovative nanodelivery systems for targeted breast cancer therapy: overcoming drug delivery challenges and exploring future perspectives

Cancer chemotherapy is often limited by insufficient drug targeting, which can cause severe adverse effects on healthy tissues. The advent of nanodelivery systems offers a potential solution to this issue. It intricately enhances drug accumulation in tumor regions, while optimizing drug solubility, ensuring colloidal stability, and promoting cellular uptake, significantly improving the precision and efficacy of treatment, opening a gentler yet more effective new path for cancer therapy. This article begins with the pathogenesis of breast cancer and extends to the current treatment methods and their shortcomings, exploring in-depth the targeting therapeutic effects of five innovative nanodelivery technologies used in the treatment of breast cancer in recent years. Finally, it discusses the potential opportunities and challenges that nanodelivery systems may face in future development.

Combating Methotrexate Resistance in Cancer Treatment: A Review on Navigating Pathways and Enhancing Its Efficacy With Fat‐Soluble Vitamins

Methotrexate (MTX), a potent analogue and antagonist of folic acid, is a first‐line treatment for rheumatoid arthritis, IBD and cancer. The development of MTX resistance contributes to the reduced efficacy and development of adverse reactions, forcing clinicians to withdraw treatment early. This drawback requires combinational approaches to combat the resistance and enhance the efficacy and safety of MTX. To provide a brief overview of MTX resistance and strategies to mitigate its aftereffects in cancer therapy, a literature‐based search was conducted using keywords such as cancer pathology, MTX mechanism and resistance, S100A4, folate uptake, folate efflux, P‐glycoprotein, beta‐catenin and anticancer properties of Vitamins A, D, E and K. Investigations encompassing in vitro studies, in vivo studies and clinical trials were reviewed to identify the mechanisms of resistance induced by MTX and the potential benefits of coadministering fat‐soluble vitamins with existing anticancer drugs. Derivates of Vitamin A could target cancer stem cells and increase chemotherapy sensitivity in non–small cell lung cancer. Similarly, calcitriol and cytotoxic medications exhibit additive or synergistic effects. Existing research revealed that fat‐soluble vitamins can inhibit drug transporters, such as P‐glycoprotein, which inhibit drug efflux, improving chemotherapy efficacy in cancer. As personalised medicine continues to evolve, incorporating combination approaches with MTX and fat‐soluble vitamins holds promise for enhancing treatment efficacy, which can counteract MTX resistance via multiple pathways and improve the safety profile.

Folic-acid-targeted drug delivery system implementing Angelica gigas polysaccharide: A potential strategy for colorectal cancer treatment

The study focuses on the development of folate-targeted conjugates utilizing Angelica gigas polysaccharide (F2) as a drug carrier for colorectal cancer therapy. We synthesized F2-C-5-FU conjugates by linking carboxymethyl-5-fluorouracil (C-5-FU) with folic acid (FA) through ester bonding. The drug release behavior of F2-C-5-FU-FA was pH-dependent, favoring release under alkaline conditions. After 96 h in phosphate buffer (pH 7.4), the conjugate exhibited a cumulative release of 54.7%, which was higher compared to other pH environments. In vitro, F2-C-5-FU-FA showed enhanced cytotoxicity and increased cellular uptake in folate receptor-positive HCT-116 cells compared to A549 cells. The conjugate also induced G2/M cell cycle arrest and modulated the BAX/BCL-2 mRNA expression ratio through the MAPK and NF-κB signaling pathways. In vivo, F2-C-5-FU-FA increased tumor fluorescence intensity, prolonged drug circulation, and reduced organ toxicity to non-target organs. The treatment promoted cancer cell apoptosis by inhibiting the expression of apoptosis-related proteins. Overall, F2-C-5-FU-FA conjugates demonstrate potential as an effective drug delivery system for targeted colorectal cancer therapy.

The mechanisms of Pin1 as targets for cancer therapy

Targeted therapy has considerable promise for the effective eradication of cancer at the primary tumor site prior to subsequent metastasis. Using this therapeutic approach, gaining an understanding of mechanistic cancer models is essential for facilitating the inhibition or suppression of tumor growth. Among different oncogenes and proteins, the protein interacting with never-in-mitosis kinase-1 (Pin1) is particularly important. The interaction between Pin1 and phosphorylated threonine-proline motifs results in significant alterations in protein structure and function. In this review, we provide a comprehensive summary of the processes involving Pin1 and its mechanisms in the context of cancer therapy. Pin1 enhances signaling pathways in a number of different human cancers and plays a pivotal role in the suppressive mechanisms relevant to cancer treatment. It is essential for the regulation of proline-directed phosphorylation and for modulating tumor suppressors. Inhibitors of Pin1, particularly naturally occurring substances, have been found to inhibit the carcinogenic activity of Pin1, and consequently this protein could represent an excellent candidate for novel cancer treatment strategies, offering a valuable therapeutic target in carcinogenesis and treatment resistance.

Two Different Responsive Organosilica Nanocarriers to Combine Chemo- and Immunotherapy against Cancer

The combination of chemo- and immunotherapy was recently demonstrated to improve a patient's response to therapy, giving rise to an emerging cancer treatment known as chemoimmunotherapy (CIT). Despite the promising benefits of CIT, the most important challenges are (i) the simultaneous or time-controlled delivery of two drugs and (ii) the selective uptake into different cells for each of the drugs: cancer cells for the chemotherapeutic and macrophages for the immunostimulation actives. Herein, a delivery strategy based on morphologically different stimuli-responsive breakable organosilica nanocarriers is exploited to transport two distinct drugs in the different cells using different times of delivery. We employ stimulus-sensitive, PEGylated organosilica nanocages to encapsulate the chemotherapeutic agent doxorubicin, which is preferentially taken up by tumor cells vs macrophages. On the other hand, similar size mesoporous organosilica nanoparticles, preferentially internalized by macrophages, are filled with the immunostimulator resiquimod. The administration in a sequential manner of the two different nanocarriers allowed us to assess the integrated effect of the combined therapy versus treatment with a single drug. In vitro work clearly shows an important reduction of tumor cell viability when both chemo- and immunotherapeutic agents are delivered.

Advances in Drug Delivery Systems for the Treatment of Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a common and catastrophic hematological neoplasm with high mortality rates. Conventional therapies, including chemotherapy, hematopoietic stem cell transplantation (HSCT), immune therapy, and targeted agents, have unsatisfactory outcomes for AML patients due to drug toxicity, off-target effects, drug resistance, drug side effects, and AML relapse and refractoriness. These intrinsic limitations of current treatments have promoted the development and application of nanomedicine for more effective and safer leukemia therapy. In this review, the classification of nanoparticles applied in AML therapy, including liposomes, polymersomes, micelles, dendrimers, and inorganic nanoparticles, is reviewed. In addition, various strategies for enhancing therapeutic targetability in nanomedicine, including the use of conjugating ligands, biomimetic-nanotechnology, and bone marrow targeting, which indicates the potential to reverse drug resistance, are discussed. The application of nanomedicine for assisting immunotherapy is also involved. Finally, the advantages and possible challenges of nanomedicine for the transition from the preclinical phase to the clinical phase are discussed.

Liposome-enabled bufalin and doxorubicin combination therapy for trastuzumab-resistant breast cancer with a focus on cancer stem cells

Breast cancer stem cells (BCSCs) play a key role in therapeutic resistance in breast cancer treatments and disease recurrence. This study aimed to develop a combination therapy loaded with pH-sensitive liposomes to kill both BCSCs and the okbulk cancer cells using trastuzumab-sensitive and resistant human epidermal growth factor receptor 2 positive (HER2+) breast cancer cell models. The anti-BCSCs effect and cytotoxicity of all-trans retinoic acid, salinomycin, and bufalin alone or in combination with doxorubicin were compared in HER2+ cell line BT-474 and a validated trastuzumab-resistant cell line, BT-474R. The most potent anti-BCSC agent was selected and loaded into a pH-sensitive liposome system. The effects of the liposomal combination on BCSCs and bulk cancer cells were assessed. Compared with BT-474, the aldehyde dehydrogenase positive BCSC population was elevated in BT-474R (3.9 vs. 23.1%). Bufalin was the most potent agent and suppressed tumorigenesis of BCSCs by ∼50%, and showed strong synergism with doxorubicin in both BT-474 and BT-474R cell lines. The liposomal combination of bufalin and doxorubicin significantly reduced the BCSC population size by 85%, and inhibited both tumorigenesis and self-renewal, although it had little effect on the migration and invasiveness. The cytotoxicity against the bulk cancer cells was also enhanced by the liposomal combination than either formulation alone in both cell lines (p < 0.001). The liposomal bufalin and doxorubicin combination therapy may effectively target both BCSCs and bulk cancer cells for a better outcome in trastuzumab-resistant HER2+ breast cancer.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

In situ injectable hydrogel encapsulating Mn/NO-based immune nano-activator for prevention of postoperative tumor recurrence

Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor resection cavity. The MPB-NO@DOX + ATRA gel was fabricated by mixing a thrombin solution, a fibrinogen solution containing all-trans retinoic acid (ATRA), and a Mn/NO-based immune nano-activator termed MPB-NO@DOX. ATRA promoted the differentiation of cancer stem cells, inhibited cancer cell migration, and affected the polarization of tumor-associated macrophages. The outer MnO2 shell disintegrated due to its reaction with glutathione and hydrogen peroxide in the cytoplasm to release Mn2+ and produce O2, resulting in the release of doxorubicin (DOX). The released DOX entered the nucleus and destroyed DNA, and the fragmented DNA cooperated with Mn2+ to activate the cGAS-STING pathway and stimulate an anti-tumor immune response. In addition, when MPB-NO@DOX was exposed to 808 nm laser irradiation, the Fe-NO bond was broken to release NO, which downregulated the expression of PD-L1 on the surface of tumor cells and reversed the immunosuppressive tumor microenvironment. In conclusion, the MPB-NO@DOX + ATRA gel exhibited excellent anti-tumor efficacy. The results of this study demonstrated the great potential of in situ injectable hydrogels in preventing postoperative tumor recurrence.

Optimized DOX Drug Deliveries via Chitosan-Mediated Nanoparticles and Stimuli Responses in Cancer Chemotherapy: A Review

Chitosan nanoparticles (NPs) serve as useful multidrug delivery carriers in cancer chemotherapy. Chitosan has considerable potential in drug delivery systems (DDSs) for targeting tumor cells. Doxorubicin (DOX) has limited application due to its resistance and lack of specificity. Chitosan NPs have been used for DOX delivery because of their biocompatibility, biodegradability, drug encapsulation efficiency, and target specificity. In this review, various types of chitosan derivatives are discussed in DDSs to enhance the effectiveness of cancer treatments. Modified chitosan-DOX NP drug deliveries with other compounds also increase the penetration and efficiency of DOX against tumor cells. We also highlight the endogenous stimuli (pH, redox, enzyme) and exogenous stimuli (light, magnetic, ultrasound), and their positive effect on DOX drug delivery via chitosan NPs. Our study sheds light on the importance of chitosan NPs for DOX drug delivery in cancer treatment and may inspire the development of more effective approaches for cancer chemotherapy.

pH-Sensitive nanodiamond co-delivery of retinal and doxorubicin boosts breast cancer chemotherapy

Herein for the first time we take the advantage of nanodiamonds (NDs) to covalently immobilize all-trans retinal (NPA) by an imine bond, allowing pH-mediated drug release. DOX is then physically adsorbed onto NPA to form an NPA@D co-loaded double drug in the sodium citrate medium, which is also susceptible to pH-triggered DOX dissociation. The cytotoxicity results showed that NPA@D could markedly inhibit the growth of DOX-sensitive MCF-7 cells in a synergetic way compared to the NP@D system of single-loaded DOX, while NPA basically showed no cytotoxicity and weak inhibition of migration. In addition, NPA@D can overcome the drug resistance of MCF-7/ADR cells, indicating that this nanodrug could evade the pumping of DOX by drug-resistant cells, but free DOX is nearly ineffective against these cells. More importantly, the fluorescence imaging of tumor-bearing mice in vivo and ex vivo demonstrated that the NPA@D was mainly accumulated in the tumor site rather than any other organ by intraperitoneal injection after 24 h, in which the fluorescence intensity of NPA@D was 19 times that of the free DOX, suggesting that a far reduced off-target effect and side effects would be expected. Therefore, this work presents a new paradigm for improving chemotherapy and reversing drug resistance using the ND platform for co-delivery of DOX and ATR.

ATRA ameliorates fibrosis by suppressing the pro-fibrotic molecule Fra2/AP-1 in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune connective tissue disease that leads to irreversible fibrosis of the skin and the internal organs. The etiology of SSc is complex, its pathophysiology is poorly understood, and clinical therapeutic options are restricted. Thus, research into medications and targets for treating fibrosis is essential and urgent. Fos-related antigen 2 (Fra2) is a transcription factor that is a member of the activator protein-1 family. Fra2 transgenic mice were shown to have spontaneous fibrosis. All-trans retinoic acid (ATRA) is a vitamin A intermediate metabolite and ligand for the retinoic acid receptor (RAR), which possesses anti-inflammatory and anti-proliferative properties. Recent research has demonstrated that ATRA also has an anti-fibrotic effect. However, the exact mechanism is not fully understood. Interestingly, we identified potential binding sites for the transcription factor RARα to the promoter region of the FRA2 gene through JASPAR and PROMO databases. In this study, the pro-fibrotic effect of Fra2 in SSc is confirmed. SSc dermal fibroblasts and bleomycin-induced fibrotic tissues of SSc animals exhibit increased levels of Fra2. Inhibition of Fra2 expression in SSc dermal fibroblasts with Fra2 siRNA markedly decreased collagen I expression. ATRA reduced the expressions of Fra2, collagen I, and α-smooth muscle actin(α-SMA) in SSc dermal fibroblasts and bleomycin-induced fibrotic tissues of SSc mice. In addition, chromatin immunoprecipitation and dual-luciferase assays demonstrated that retinoic acid receptor RARα binds to the FRA2 promoter and modulates its transcriptional activity. ATRA decreases collagen I expression both in vivo and in vitro via the reduction of Fra2 expression. This work establishes the rationale for expanding the use of ATRA in the treatment of SSc and indicates that Fra2 can be used as an anti-fibrotic target.

Nattokinase-Mediated Regulation of Tumor Physical Microenvironment to Enhance Chemotherapy, Radiotherapy, and CAR-T Therapy of Solid Tumor

The therapy of solid tumors is always hampered by the intrinsic tumor physical microenvironment (TPME) featured with compact and rigid extracellular matrix (ECM) microstructures. Herein, we introduce nattokinase (NKase), a thrombolytic healthcare drug, to comprehensively regulate the TPME for versatile enhancement of various therapy modalities. Intratumoral injection of NKase not only degrades the major ECM component fibronectin but also inhibits cancer-associated fibroblasts (CAFs) in generating fibrosis, resulting in decreased tumor stiffness, enhanced perfusion, and hypoxia alleviation. The NKase-mediated regulation of the TPME significantly promotes the tumoral accumulation of therapeutic agents, leading to efficient chemotherapy without inducing side effects. Additionally, the enhancement of tumor radiotherapy based on radiosensitizers was also achieved by the pretreatment of intratumorally injected NKase, which could be ascribed to the elevated oxygen saturation level in NKase-treated tumors. Moreover, a xenografted human breast MDB-MA-231 tumor model is established to evaluate the influence of NKase on chimeric antigen receptor (CAR)-T cell therapy, illustrating that the pretreatment of NKase could boost the infiltration of CAR-T cells into tumors and thus be a benefit for tumor inhibition. These findings demonstrate the great promise of the NKase-regulated TPME as a translational strategy for universal enhancement of therapeutic efficacy in solid tumors by various treatments.

Smart Chondroitin Sulfate Micelles for Effective Targeted Delivery of Doxorubicin Against Breast Cancer Metastasis

Introduction

Metastasis is a major challenge in breast cancer therapy. The successful chemotherapy of breast cancer largely depends on the ability to block the metastatic process. Herein, we designed a dual-targeting and stimuli-responsive drug delivery system for targeted drug delivery against breast cancer metastasis.

Methods

AS1411 aptamer-modified chondroitin sulfate A-ss-deoxycholic acid (ACSSD) was synthesized, and the unmodified CSSD was used as the control. Chemotherapeutic drug doxorubicin (DOX)-containing ACSSD (D-ACSSD) micelles were prepared by a dialysis method. The ACSSD conjugate was confirmed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), dynamic light scattering (DLS), and transmission electron microscopy (TEM). In vitro cellular uptake and cytotoxicity of D-ACSSD micelles were studied by confocal laser scanning microscopy (CLSM) and MTT assay in breast tumor cells. The inhibition capability of D-ACSSD micelles in cell migration and invasion was carried out in 4T1 cells. In vivo antitumor activity of DOX-containing micelles was investigated in metastatic 4T1-bearing Balb/c mice.

Results

D-ACSSD and DOX-loaded CSSD (D-CSSD) micelles exhibited high drug encapsulation content and reduction-responsive characteristics. D-ACSSD micelles were spherical in shape. Compared with D-CSSD, D-ACSSD showed higher cellular uptake and more potent killing activity in 4T1 and MDA-MB-231 cells. Additionally, D-ACSSD exhibited stronger inhibitory effects on the invasion and migration of highly metastatic 4T1 cells than unmodified D-CSSD. Among the DOX-containing formulations, D-ACSSD micelles presented the most effective inhibition of tumor growth and lung metastasis in orthotopic 4T1-bearing mice in vivo. It also revealed that ACSSD micelles did not exhibit obvious systemic toxicity.

Conclusion

The smart D-ACSSD micelles could be a promising delivery system for the therapy of metastatic breast cancer.

Novel pH-sensitive nanoparticles based on prodrug strategy to delivery All-Trans Retinoic Acid for breast cancer

Developing chemotherapy with nanoparticle-based prodrugs provides promising strategies for improving the safety and delivery of anti-cancer drugs therapeutics and effective cancer treatment. Herein, we developed a pH-sensitive prodrug delivery system (All-Trans-Retinoic Acid (ATRA) grafted poly (β-amino esters) (PBAE) copolymers, ATRA-g-PBAE) for delivery of ATRA with some physicochemical and biological properties. The in vitro release of ATRA-g-PBAE prodrug nanoparticles (PNPs) was sustained-release and pH-sensitive. The cytotoxicity and uptake of different preparations in vitro were evaluated on MCF-7 cells at pH 7.4 and 5.5. The carrier PBAE had no cytotoxicity, and ATRA-g-PBAE PNPs could significantly inhibit cell growth at pH 5.5. MCF-7 cells treated with Cy5.5 grafted PBAE (Cy5.5-PBAE) showed stronger fluorescence signals at pH 5.5. Meanwhile, ATRA-g-PBAE PNPs entered the cell via a clathrin-mediated endocytic pathway. Subsequently, PBAE protonation facilitated the escape of PNPs from the lysosome and released the drug. ATRA-g-PBAE seems promising as a novel pH-sensitive prodrug to overcome the limitations of ATRA for breast cancer therapy.

Natural Products-Based Nanoformulations: A New Approach Targeting CSCs to Cancer Therapy

Cancer stem cells (CSCs) lead to the occurrence and progression of cancer due to their strong tumorigenic, self-renewal, and multidirectional differentiation abilities. Existing cancer treatment methods cannot effectively kill or inhibit CSCs but instead enrich them and produce stronger proliferation, invasion, and metastasis capabilities, resulting in cancer recurrence and treatment resistance, which has become a difficult problem in clinical treatment. Therefore, targeting CSCs may be the most promising approach for comprehensive cancer therapy in the future. A variety of natural products (NP) have significant antitumor effects and have been identified to target and inhibit CSCs. However, pharmacokinetic defects and off-target effects have greatly hindered their clinical translation. NP-based nanoformulations (NPNs) have tremendous potential to overcome the disadvantages of NP against CSCs through site-specific delivery and by improving their pharmacokinetic parameters. In this review, we summarize the recent progress of NPNs targeting CSCs in cancer therapy, looking forward to transforming preclinical research results into clinical applications and bringing new prospects for cancer treatment.

Targeting prolyl isomerase Pin1 as a promising strategy to overcome resistance to cancer therapies

The development of tumor therapeutic resistance is one of the important reasons for the failure of antitumor therapy. Starting with multiple targets and multiple signaling pathways is helpful in understanding the mechanism of tumor resistance. The overexpression of prolyl isomerase Pin1 is highly correlated with the malignancy of cancer, since Pin1 controls many oncogenes and tumor suppressors, as well as a variety of cancer-driving signaling pathways. Strikingly, numerous studies have shown that Pin1 is directly involved in therapeutic resistance. In this review, we mainly summarize the functions and mechanisms of Pin1 in therapeutic resistance of multifarious cancers, such as breast, liver, and pancreatic carcinomas. Furtherly, from the perspective of Pin1-driven cancer signaling pathways including Raf/MEK/ERK, PI3K/Akt, Wnt/β-catenin, NF-κB, as well as Pin1 inhibitors containing juglone, epigallocatechin-3-gallate (EGCG), all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), it is better to demonstrate the important potential role and mechanism of Pin1 in resistance and sensitization to cancer therapies. It will provide new therapeutic approaches for clinical reversal and prevention of tumor resistance by employing synergistic administration of Pin1 inhibitors and chemotherapeutics, implementing combination therapy of Pin1-related cancer signaling pathway inhibitors and Pin1 inhibitors, and exploiting novel Pin1-specific inhibitors.

Development of a prognostic signature based on immune-related genes and the correlation with immune microenvironment in breast cancer

Breast cancer (BC) is an inflammatory tumor caused by a variety of pathological factors, and is still the most common malignant tumor in women. Immune-related genes (IRGs) play a prominent role in the oncogenesis and progression of BC, and are of tumor-specific expression patterns that would benefit the prognosis evaluation. However, there were no systematic studies concerning the possibilities of IRGs in BC prognosis. In this study, the Cancer Genome Atlas (TCGA) database was used to integrate the expression profiles of IRG with the overall survival (OS) rate of 1039 breast cancer patients. The Cox regression analysis was used to predict the survival-related IRGs in BC. Then, we successfully screened a total of 6 IRGs, including PSME2, ULBP2, IGHE, SCG2, SDC1, and SSTR1, and accordingly constructed a prognosis prediction model of BC. Based on the IRG-related model, the BC patients were divided into high- and low-risk groups, and the association between the prognostic model and tumor immune microenvironment (TME) was further explored. The prognostic model reflected the infiltration of various immune cells. Moreover, the low-risk group was found to be with higher immunophenoscore and distinct mutation signatures compared with the high-risk group. The histological validation showed that SDC1, as well as M2 macrophage biomarker CD206, were both of higher abundance in BC samples of high-risk patients, compared with those of low-risk patients. Our results identify the clinically significant IRGs and demonstrate the importance of the IRG-based immune prognostic model in BC monitoring, prognosis prediction, and therapy.