PRODH safeguards human naive pluripotency by limiting mitochondrial oxidative phosphorylation and reactive oxygen species production.

Naive human embryonic stem cells (hESCs) that resemble the pre-implantation epiblasts are fueled by a combination of aerobic glycolysis and oxidative phosphorylation, but their mitochondrial regulators are poorly understood. Here we report that, proline dehydrogenase (PRODH), a mitochondria-localized proline metabolism enzyme, is dramatically upregulated in naive hESCs compared to their primed counterparts. The upregulation of PRODH is induced by a reduction in c-Myc expression that is dependent on PD0325901, a MEK inhibitor routinely present in naive hESC culture media. PRODH knockdown in naive hESCs significantly promoted mitochondrial oxidative phosphorylation (mtOXPHOS) and reactive oxygen species (ROS) production that triggered autophagy, DNA damage, and apoptosis. Remarkably, MitoQ, a mitochondria-targeted antioxidant, effectively restored the pluripotency and proliferation of PRODH-knockdown naive hESCs, indicating that PRODH maintains naive pluripotency by preventing excessive ROS production. Concomitantly, PRODH knockdown significantly slowed down the proteolytic degradation of multiple key mitochondrial electron transport chain complex proteins. Thus, we revealed a crucial role of PRODH in limiting mtOXPHOS and ROS production, and thereby safeguarding naive pluripotency of hESCs.

Influence of sex on outcomes of liver transplantation for hepatocellular carcinoma: a multicenter cohort study in China.

OBJECTIVE: Sex-specific differences are observed in various liver diseases, but the influence of sex on the outcomes of hepatocellular carcinoma (HCC) after liver transplantation (LT) remains to be determined. This study is the first Chinese nationwide investigation of the role of sex in post-LT outcomes in patients with HCC. METHODS: Data for recipients with HCC registered in the China Liver Transplant Registry between January 2015 and December 2020 were analyzed. The associations between donor, recipient, or donor-recipient transplant patterns by sex and the post-LT outcomes were studied with propensity score matching (PSM). The survival associated with different sex-based donor-recipient transplant patterns was further studied. RESULTS: Among 3,769 patients enrolled in this study, the 1-, 3-, and 5-year overall survival (OS) rates of patients with HCC after LT were 96.1%, 86.4%, and 78.5%, respectively, in female recipients, and 95.8%, 79.0%, and 70.7%, respectively, in male recipients after PSM (P = 0.009). However, the OS was comparable between recipients with female donors and male donors. Multivariate analysis indicated that male recipient sex was a risk factor for post-LT survival (HR = 1.381, P = 0.046). Among the donor-recipient transplant patterns, the male-male donor-recipient transplant pattern was associated with the poorest post-LT survival (P < 0.05). CONCLUSIONS: Our findings highlighted that the post-LT outcomes of female recipients were significantly superior to those of male recipients, and the male-male donor-recipient transplant pattern was associated with the poorest post-LT survival. Livers from male donors may provide the most benefit to female recipients. Our results indicate that sex should be considered as a critical factor in organ allocation.

Polyethylene glycol (PEG)-associated immune responses triggered by clinically relevant lipid nanoparticles in rats.

With the large-scale vaccination of lipid nanoparticles (LNP)-based COVID-19 mRNA vaccines, elucidating the potential polyethylene glycol (PEG)-associated immune responses triggered by clinically relevant LNP has become imminent. However, inconsistent findings were observed across very limited population-based studies. Herein we initiated a study using LNP carrier of Comirnaty® as a representative, and simulated real-world clinical practice covering a series of time points and various doses correlated with approved LNP-delivered drugs in a rat model. We demonstrated the time- and dose-dependency of LNP-induced anti-PEG antibodies in rats. As a thymus-independent antigen, LNP unexpectedly induced isotype switch and immune memory, leading to rapid enhancement and longer lasting time of anti-PEG IgM and IgG upon re-injection in rats. Importantly, initial LNP injection accelerated the blood clearance of subsequent dosing in rats. These findings refine our understandings on LNP and possibly other PEG derivatives, and may promote optimization of related premarket guidelines and clinical protocols.

Identification of a brand intratumor microbiome signature for predicting prognosis of hepatocellular carcinoma.

PURPOSE: Given that prognosis of hepatocellular carcinoma (HCC) differs dramatically, it is imperative to uncover effective and available prognostic biomarker(s). The intratumor microbiome plays a significant role in the response to tumor microenvironment, we aimed to identify an intratumor microbiome signature for predicting the prognosis of HCC patients accurately and investigate its possible mechanisms subsequently. METHODS: The TCGA HCC microbiome data (TCGA-LIHC-microbiome) was downloaded from cBioPortal. To create an intratumor microbiome-related prognostic signature, univariate and multivariate Cox regression analyses were used to quantify the association of microbial abundance and patients' overall survival (OS), as well as their diseases specific survival (DSS). The performance of the scoring model was evaluated by the area under the ROC curve (AUC). Based on the microbiome-related signature, clinical factors, and multi-omics molecular subtypes on the basis of "icluster" algorithm, nomograms were established to predict OS and DSS. Patients were further clustered into three subtypes based on their microbiome-related characteristics by consensus clustering. Moreover, deconvolution algorithm, weighted correlation network analysis (WGCNA) and gene set variation analysis (GSVA) were used to investigate the potential mechanisms. RESULTS: In TCGA LIHC microbiome data, the abundances of 166 genera among the total 1406 genera were considerably associated with HCC patients' OS. From that filtered dataset we identified a 27-microbe prognostic signature and developed a microbiome-related score (MRS) model. Compared with those in the relatively low-risk group, patients in higher-risk group own a much worse OS (P < 0.0001). Besides, the time-dependent ROC curves with MRS showed excellent predictive efficacy both in OS and DSS. Moreover, MRS is an independent prognostic factor for OS and DSS over clinical factors and multi-omics-based molecular subtypes. The integration of MRS into nomograms significantly improved the efficacy of prognosis prediction (1-year AUC:0.849, 3-year AUC: 0.825, 5-year AUC: 0.822). The analysis of microbiome-based subtypes on their immune characteristics and specific gene modules inferred that the intratumor microbiome may affect the HCC patients' prognosis via modulating the cancer stemness and immune response. CONCLUSION: MRS, a 27 intratumor microbiome-related prognostic model, was successfully established to predict HCC patients overall survive independently. And the possible underlying mechanisms were also investigated to provide a potential intervention strategy.

Intestinal microecology in mice bearing diethylnitrosamine-induced primary hepatocellular carcinoma.

OBJECTIVE: To explore the characteristics of intestinal microecology in hepatocellular carcinoma (HCC) model mice. METHODS: C57BL/6 male mice aged 2 weeks were divided into normal control group and HCC model group. Mice in HCC model group were exposed to a single intraperitoneal injection of diethylnitrosamine (DEN) 2 weeks after birth; the surviving mice were intraperitoneally injected with 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP), once every 2 weeks for 8 times starting from the 4 th week after birth. Mice in each group were randomly selected and sacrificed at 10 th, 18 th and 32 nd weeks after birth, respectively, the liver tissue samples were obtained for histopathological examination. At the 32 nd week, all mice in both groups were sacrificed and the feces samples were collected under sterile conditions right before the sacrifice. The feces samples were sequenced for the V3-V4 hypervariable regions of the 16S rRNA gene, and the species abundance, flora diversity and phenotype, as well as flora correlation and functional prediction were analyzed. RESULTS: Alpha diversity analysis showed that all Good's coverage reached the maximum value of 1.00, and the differences in the Observed features, Chao1 index, Shannon index and Simpson index of the intestinal flora of mice between normal control group and HCC model group were all statistically significant (all P<0.05). Beta diversity analysis showed that PCoA based on weighted or unweighted Unifrac distances all yielded R>0, confirming that the intra-group differences of the samples were less than the inter-group differences; the trend of separation between the two groups was significant ( P<0.05). Bacteroidetes, Firmicutes, Actinobacteria and Patescibacteria were the dominant taxa at the phylum level in both normal control group and HCC model group. However, compared with normal control group, the abundance of Bacteroidetes in HCC model group was significantly decreased ( P<0.01), while the abundance of Patescibacteria was significantly increased ( P<0.05). Moreover, the dominant taxa at the genus level in normal control group mainly included Muribaculaceae_unclassified, Paramuribaculum, Muribaculum, Lachnospiraceae_NK4A 136 group, Olsenella. The dominant taxa at the genus level in HCC model group mainly included Akkermansia, Dubosiella, Muribaculaceae_unclassified, Lachnospiraceae_NK4A 136 group, Coriobacteriaceae_UCG-002. There were 30 genera with statistically significant differences in relative abundance at the genus level between the two groups (all P<0.05). LEfSe analysis of the intestinal flora of mice in the two groups revealed a total of 14 multi-level differential taxa (all P<0.05, LDA score>4.0), which were mainly enriched in Bacteroidetes. The enrichment of 10 differential taxa including Bacteroidetes, Bacteroidia, Bacteroidales, Muribaculaceae, etc. were found in normal control group, and the enrichment of 4 differential taxa including Dubosiella, Peptostreptococus, etc. were found in HCC model group. There were both positive and negative correlations between the dominant intestinal genera in normal control group (|rho|>0.5, P<0.05), while the correlations of the dominant intestinal genera in HCC model group, being less complex than that in normal control group, were all positive. The relative abundance of gram positive and mobile element containing in the intestinal flora of mice in HCC model group was significantly up-regulated compared with normal control group (both P<0.05), while that of gram negative ( P<0.05) and pathogenic potential ( P<0.05) was significantly down-regulated. The metabolic pathways of the intestinal flora in the two groups were significantly different. For instance, 18 metabolic pathways were enriched in normal control group (all P<0.005), including those related to energy metabolism, cell division, nucleotide metabolism, etc., while 12 metabolic pathways were enriched in HCC model group (all P<0.005), including those related to energy metabolism, amino acid metabolism, carbohydrate metabolism, etc. Conclusions: The amount of intestinal flora in DEN-induced primary HCC model mice decreased, and the composition, correlation, phenotype and function of the intestinal flora in mice were significantly altered. Bacteroidetes at the phylum level, as well as several microbial taxa at the genus level such as Muribaculaceae_unclassified, Muribaculum, Peptostreptococus and Dubosiella could be closely associated with DEN-induced primary HCC in mice.

A nanotherapeutic strategy to overcome chemoresistance to irinotecan/7-ethyl-10-hydroxy-camptothecin in colorectal cancer.

Clinical development of 7-ethyl-10­hydroxy-camptothecin (SN38), the active metabolite of irinotecan (CPT-11), is hindered by its insolubility and poor stability. Another obstacle is that tumors could become resistant to SN38/CPT-11 through multiple mechanisms involving breast cancer resistance protein (BCRP). Herein one of the most potent and selective BCRP inhibitors, Ko143, is encapsulated into a recently constructed prodrug PEG-S-S-SN38 displaying a high and fixed drug loading, multiple intratumoral stimuli (oxidative stress, GSH and esterase)-responsive drug release and significant in vitro and in vivo superiorities over CPT-11. The obtained "combo" for simultaneous delivery of SN38 and Ko143, named as BI@PEG-SN38, has a high SN38 loading efficacy (14.85 wt.%) and a good Ko143 encapsulation efficacy (3.79%). Through generating panels of human colorectal cancer models expressing altered levels of BCRP via lentiviral transfection and CRISPR-Cas9, characteristics of different drug formulations are carefully evaluated. Impressively, BI@PEG-SN38 nanoparticles effectively reverse chemoresistance to CPT-11 (resistance index dropping from ∼274.00-456.00 to ∼1.70-4.68) and PEG-S-S-SN38 (resistance index dropping from ∼5.83-14.00 to ∼1.70-4.68) in three BCRP-overexpressing cancer cell lines. More importantly, reversal of BCRP-mediated chemoresistance to CPT-11 (P values lower than 0.001-0.0001) and PEG-S-S-SN38 (P values lower than 0.01-0.001) by BI@PEG-SN38 nanoparticles are further confirmed with two panels of colorectal cancer xenograft models in vivo. As the first nano-formulation of Ko143 and the first systemic co-delivery vehicle of SN38/CPT-11 and a BCRP inhibitor, BI@PEG-SN38 provides a new approach for resolving the bottlenecks for clinical translation of SN38 and numerous "chemosensitizers" like Ko143, and exhibits promising applicability in precision cancer medicine. STATEMENT OF SIGNIFICANCE: To resolve the bottlenecks in clinical application of anticancer agents SN38/CPT-11 and the most potent breast cancer resistant protein (BCRP) inhibitor Ko143, a "combo" nanotherapeutic simultaneously delivering SN38 and Ko143 was constructed and named as BI@PEG-SN38. By generating panels of colorectal cancer models, we demonstrate that BI@PEG-SN38 nanoparticles effectively and selectively reversed BCRP-mediated tumor resistance to SN38/CPT-11 in vitro and in vivo. As the first nano-formulation of Ko143 and the first systemic co-delivery vehicle of SN38/CPT-11 and a BCRP inhibitor, BI@PEG-SN38 provides a new strategy for clinical development of SN38 and numerous "chemosensitizers", and exhibits promising applicability in precision cancer medicine. Panels of cancer cell lines established here provides a useful platform for BCRP- and cancer-related research and technology development.

The Role of Formyl Peptide Receptor 1 in Uterine Contraction During Parturition.

Parturition involves the transformation of the quiescent myometrium into a highly excitable and contractile state, a process that is driven by changes in myometrial gene expression. This study aimed to identify myometrial transcriptomic signatures and potential novel hub genes in parturition, which have great significance for understanding the underlying mechanisms of successful parturition and treating labor-associated pathologies such as preterm birth. In our study, comparative transcriptome analysis was carried out on human myometrial tissues collected from women undergoing caesarean section at term in the presence (TL = 8) and absence of labor (TNL = 8). A total of 582 differentially expressed genes (DEGs) between TL and TNL tissues were identified. Gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG) and gene set enrichment analysis (GSEA) revealed that the DEGs were enriched in signal transduction, regulation of signaling receptor activity, inflammatory response, cytokine-cytokine receptor interaction, IL-17 signaling pathway, TNF signaling pathway, among others. Thus, transcriptome analysis of the myometrium during term labor revealed that labor onset was associated with an inflammatory response. Moreover, protein-protein interactions network analysis identified FPR1, CXCL8, CXCL1, BDKRB2, BDKRB1, and CXCL2 as the hub genes associated with onset of labor. Formyl peptide receptor 1 (FPR1) was highly expressed in laboring myometrial tissues, with the activation of FPR1 in vitro experiments resulting in increased myometrial contraction. Our findings demonstrate the novel role of FPR1 as a modulator of myometrial contraction.

Lipid Metabolism in Tumor-Associated Natural Killer Cells.

Accumulative data demonstrate that during the initiation and progression of tumors, several types of cellular components in tumor microenvironment, including tumor cells and immune cells, exhibit malfunctions in cellular energy metabolism. For instance, lipid metabolism impairments in immune cells are crucial in coordinating immunosuppression and tumor immune escape. In particular, excessive lipids have been shown to exhibit negative effects on innate immunity. Previous studies on lipid metabolism in immune cells are mainly focused on macrophages and T lymphocytes. Although natural killer (NK) cells are major players in the innate elimination of virus, bacteria, and tumor cells, available literature reports related with lipid metabolism in NK cells and tumor-associated NK (TANK) cells are very sparse. Despite these, the importance and clinical relevance of the crosstalk among lipid metabolism, NK/TANK cells, and tumors have been clearly indicated. In this chapter, following a general description of NK and TANK cells, our knowledge on the regulation of lipid metabolism in NK cells is reviewed, with an emphasis on the roles of mTOR and SREBP signaling. Then the interactions between lipid metabolism and NK/TANK cells under pathological conditions, e.g., obesity and cancer, were carefully introduced. As there is an urgent need to reveal more regulators and to clarify detailed molecular mechanisms by which lipid metabolism interacts with NK/TANK cells, several categories of potential regulators/pathways, as well as the challenges and perspectives in this emerging field, are discussed.

Application of star poly(ethylene glycol) derivatives in drug delivery and controlled release.

Multi-arm star poly(ethylene glycol) (PEG) polymers have a number of advantages over linear PEG polymers when used as carriers for drug delivery and controlled release. For instance, they have more terminals that can be modified to form multi-functional delivery systems with significantly increased drug loading. They can form micelles with higher stability and lower critical micelle concentration (CMC), which helps to improve the blood circulation and reduce the unfavorable burst drug release. Moreover, star PEG polymers can form three-dimensional hydrogels with controllable size and adjustable functions through cross-linking. Indeed, these unique advantages of star PEG polymers have promoted investigations on star PEG-based drug delivery systems. Herein, for the first time, we carefully reviewed the advances on the research and development of star PEG polymers, especially the 4-, 6- and 8-armed star PEG polymers, in delivery and controlled release of a series of bioactive agents, including both small molecules and biomacromolecules. Opportunities and challenges for successful translation of star PEG-based drug formulations into clinical use were also discussed.

Advances in delivery of Irinotecan (CPT-11) active metabolite 7-ethyl-10-hydroxycamptothecin.

CPT-11 is a first-line chemotherapy for advanced or metastatic colorectal cancers. 7-Ethyl-10-hydroxycamptothecin (SN38), the active metabolite of CPT-11, has an anticancer efficacy 100-1000 folds more than CPT-11 in vitro. However, the drawbacks such as ultralow solubility and poor stability, greatly limit the clinical applications of SN38. Recently, SN38-based nanomedicines have greatly improved the pharmaceutical and therapeutic characteristics of SN38. In addition, these nanosized delivery systems can target tumor tissues via the EPR effect and/or active-targeting strategies, thereby significantly improving anticancer efficacy, reducing side effects and reversing drug resistance. This review focuses on the advances of nano-delivery systems for SN38. We categorize the published studies into two groups, physical encapsulation and chemical conjugation, for the development of SN38 nano-delivery systems, and particularly summarize those for active tumor targeting. The advantages and shortcomings of current SN38 nano-delivery systems, aiming to develop more potent SN38 nano-delivery systems, are also discussed.

Cancer Immunotherapy Based on Natural Killer Cells: Current Progress and New Opportunities.

Cancer immunotherapy has been firmly established as a new milestone for cancer therapy, with the development of multiple immune cells as therapeutic tools. Natural killer (NK) cells are innate immune cells endowed with potent cytolytic activity against tumors, and meanwhile act as regulatory cells for the immune system. The efficacy of NK cell-mediated immunotherapy can be enhanced by immune stimulants such as cytokines and antibodies, and adoptive transfer of activated NK cells expanded ex vivo. In addition, NK cells can arm themselves with chimeric antigen receptors (CARs), which may greatly enhance their anti-tumor activity. Most recently, extracellular vesicles (EVs) derived from NK cells show promising anti-tumor effects in preclinical studies. Herein, we carefully review the current progress in these NK cell-based immunotherapeutic strategies (NK cells combined with stimulants, adoptive transfer of NK cells, CAR-NK cells, and NK EVs) for the treatment of cancers, and discussed the challenges and opportunities for opening a new horizon for cancer immunotherapy.

Six-gene Assay as a new biomarker in the blood of patients with colorectal cancer: establishment and clinical validation.

Colorectal cancer (CRC) is the second most common cancer in men and the third most common cancer in women. Although long-term survival has improved over the past 30 years, at least 50% of patients with CRC will develop metastases after diagnosis. In this study, we examined whether quantifying the mRNA of six CRC-related genes in the blood could improve disease assessment through detection of circulating tumor cells (CTC), and thereby improve progression prediction in relapsed CRC patients. Cell spiking assay and RT-PCR were performed with blood samples from healthy volunteers spiked with six CRC cell lines to generate an algorithm, herein called the Six-gene Assay, based on six genes (CEA, EpCAM, CK19, MUC1, EGFR and C-Met) for CTC detection. The CTCs of 50 relapsed CRC patients were then respectively measured by CEA Gene Assay (single-gene assay control) and Six-gene Assay. Subsequently, receiver operating characteristic analysis of the CTC panel performance in diagnosing CRC was conducted for both assays. Moreover, the 2-year progression-free survival (PFS) of all patients was collected, and the application of CEA Gene Assay and Six-gene Assay in predicting PFS was carefully evaluated with different CTC cutoff values. Encouragingly, we successfully constructed the first multiple gene-based algorithm, named the Six-gene Assay, for CTC detection in CRC patients. Six-gene Assay was more sensitive than CEA Gene Assay; for instance, in 50 CRC patients, the positive rate of Six-gene Assay in CTC detection was 82%, whereas that of CEA Gene Assay was only 70%. Moreover, Six-gene Assay was more sensitive and accurate than CEA Gene Assay in diagnosing CRC as well as predicting the 2-year PFS of CRC patients. Statistical analysis demonstrated that CTC numbers measured by Six-gene Assay were significantly associated with 2-year PFS. This novel Six-gene Assay improves the definition of disease status and correlates with PFS in relapsed CRC, and thus holds promise for future clinical applications.

Functionalized Nanoparticles Efficiently Enhancing the Targeted Delivery, Tumor Penetration, and Anticancer Activity of 7-Ethyl-10-Hydroxycamptothecin.

The enhanced permeability and retention (EPR) effect of tumors is much more complex than initially defined, and it alone is not sufficient for targeted delivery of nanosized agents. Meanwhile, poor tumor penetration is another major challenge for the treatment of solid tumors using nanoparticles. Development of delivery systems for SN38, the active metabolite of CPT-11 in human and a very potent anticancer molecule, has become an attractive research area. PEGx -p(HEMASN38)y (x and y are viable), a prodrug synthesized by using polyethylene glycol (PEG) as initiator and SN38 as monomer through atom transfer radical polymeration (ATRP) method, is previously reported. Using PEG2.4K -p(HEMASN38)3K as a model prodrug, herein an active-targeted strategy decorated with cys-arg-gly-asp-lys (CRGDK), a peptide specifically binds to neuropilin-1 overexpressed by tumor vessels and tumor cells, is successfully established to further improve the delivery and efficacy of SN38. CRGDK-functionalized PEG2.4K -p(HEMASN38)3K (C-SN38) nanoparticles and nonfunctionalized control (B-SN38) are prepared with two distinct sizes, 30 and 100 nm. Their physiochemical and biological characteristics are investigated in vitro and in vivo with multiple tumor models. It is demonstrated for the first time that CRGDK functionalization can be a promising strategy for efficient delivery of SN38, and C-SN38 is a potent drug candidate for the treatment of neuropilin-1 overexpressing tumors.

Terminating the criminal collaboration in pancreatic cancer: Nanoparticle-based synergistic therapy for overcoming fibroblast-induced drug resistance.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with a dismal overall prognosis mainly unchanged over the past decades. PDAC is generally refractory to conventional treatments, and thus novel therapies are urgently needed. Recently, accumulating evidence has indicated that human pancreatic stellate cells (PSCs) facilitate PDAC development and drug resistance through paracrine activation of hedgehog pathway. Here, we report that smart SN38 (active metabolite of irinotecan) polymeric prodrug-based nanoparticles effectively encapsulate the commercial hedgehog pathway inhibitor GDC-0449 for co-delivery. More intriguingly, we obtained size-tunable nanoparticles with increased GDC-0449 loading efficiency by simply extending the chain length of the hydrophobic SN38 block. To better evaluate the efficacy and investigate the synergistic mechanisms, we immortalized human PSCs and established fibroblast-containing models in vitro and in vivo. In PSCs, BxPC-3 cells and MIA PaCa-2 cells, GDC-0449 suppressed the co-culture induced up-regulations of the two drug resistance contributors: sonic hedgehog transcription factor glioma-associated protein1 (GLI-1) and UGT1A glucuronosyltransferase. Importantly, the nanoparticle-mediated co-delivery system exhibited potent antitumor efficacy with enhanced apoptosis and reduced collagen, α-SMA and GLI-1 expression in tumor tissues. These findings reveal a potential strategy to utilize nanoparticle-mediated drug co-delivery platform as an effective combination therapy for fibroblast-enriched PDAC.

A multi-stimuli responsive nanoparticulate SN38 prodrug for cancer chemotherapy.

Modification of drug delivery systems (DDSs) with stimuli-responsive elements could significantly increase the tumor-specific delivery of anticancer drugs. Herein we synthesized a novel multiple stimuli-responsive SN38 prodrug, named PEG-S-S-SN38, by conjugating PEG (MW: 2000) and SN38 with disulfide bonds and carbonic ester linkages as linkers for efficient delivery of SN38. The amphiphilic PEG-S-S-SN38, with a high SN38 loading content, could self-assemble into nanoparticles (NPs) with a stable diameter of ∼73 nm. PEG-S-S-SN38 NPs release SN38 very slowly at physiological pH, while they quickly release SN38 in the presence of GSH, esterase and H2O2, all of which are abundant in the cytoplasm of cancer cells. PEG-S-S-SN38 NPs could be quickly internalized into tumor cells, achieve vesicular escape and nuclear localization, and exhibit remarkable in vitro anticancer activity similar to SN38. Encouragingly, PEG-S-S-SN38 NPs exhibit the same effects on cell cycle regulations as SN38 in vitro. Most importantly, the inhibition rate of tumor growth induced by PEG-S-S-SN38 NPs in a xenograft tumor model reached 72.49% ± 6.26%, which was nearly double that of the corresponding clinical drug CPT-11 (38.64% ± 13.04%) at a dosage equivalent to 10 mg kg-1 SN38. Our data suggest that the multi-stimuli responsiveness of PEG-S-S-SN38 NPs remarkably enhances their therapeutic activity against heterogeneous or mixed cell population in tumors, making this new DDS a promising alternative to CPT-11 for cancer treatment.

Fulvestrant reverses doxorubicin resistance in multidrug-resistant breast cell lines independent of estrogen receptor expression.

Drug resistance, a major obstacle to successful cancer chemotherapy, frequently occurs in recurrent or metastatic breast cancer and results in poor clinical response. Fulvestrant is a new type of selective estrogen receptor (ER) downregulator and a promising endocrine therapy for breast cancer. In this study, we evaluated the combination treatment of fulvestrant and doxorubicin in ER-negative multidrug-resistant (MDR) breast cancer cell lines Bads­200 and Bats­72. Fulvestrant potentiated doxorubicin-induced cytotoxicity, apoptosis and G2/M arrest with upregulation of cyclin B1. It functioned as a substrate for P-glycoprotein (P-gp) without affecting its expression. Furthermore, fulvestrant not only restored the intracellular accumulation of doxorubicin but also relocalized it to the nuclei in Bats­72 and Bads­200 cells, which may be another potential mechanism of reversal of P-gp mediated doxorubicin resistance. These results indicated that the combination of fulvestrant and doxorubicin-based chemotherapy may be feasible and effective for patients with advanced breast cancer.

Self-Assembling Doxorubicin Prodrug Forming Nanoparticles and Effectively Reversing Drug Resistance In Vitro and In Vivo.

Doxorubicin (DOX) is a widely used chemotherapeutic drug to treat a range of cancers. However, its unfavorable effects, particularly the cardiotoxicity and the induction of multidrug resistance (MDR), significantly limit its clinical applications. Herein, a novel doxorubicin prodrug, PEG2K -DOX, is synthesized by conjugating a deprotonated doxorubicin molecule with the polyethylene glycol (PEG, MW: 2K) chain via pH-responsive hydrazone bond, and its potential as a better alternative than doxorubicin is evaluated. The data show that the amphiphilic PEG2K -DOX can self-assemble into stable nanoparticles with a high and fixed doxorubicin loading content (≈20 wt%), a favorable size of 91.5 nm with a narrow polydispersity (PDI = 0.14), good stability, and pH-dependent release behavior due to the acid-cleavable linkage between PEG and doxorubicin. Although doxorubicin hardly accumulates in MDR cells, PEG2K -DOX nanoparticles significantly increase the cellular uptake and cell-killing activity of doxorubicin in two MDR cancer cell lines MCF-7/ADR and KBv200, with the IC50 values dropped to 1.130% and 42.467% of doxorubicin, respectively. More impressively, PEG2K -DOX nanoparticles exhibit significantly improved plasma pharmacokinetics, increased in vivo therapeutic efficacy against MDR xenograft tumors, and better in vivo safety compared with doxorubicin. PEG2K -DOX nanoparticles hold the promise to become a better alternative than doxorubicin for cancer treatment, especially for MDR tumors.

Non-viral Delivery Systems for the Application in p53 Cancer Gene Therapy.

A key barrier to the development of gene therapy remains the lack of safe, efficient and easily controllable vehicles for gene delivery. The fundamental problems associated with the viral vehicles, e.g. lack of specificity and immunogenic potential, have driven the development of non-viral systems of gene delivery. In the last decade, studies on p53 gene replacement therapy have dominated the literature. Although clinical trials of p53 gene therapy have achieved limited success, it remains the only tumor suppressor gene to be evaluated formally in clinical trials for cancer treatment, with increasing focus on delivery using non-viral systems. In this article, we particularly review current investigations on p53 gene delivery using non-viral methods, including both physical and chemical approaches, with an emphasis on the latter. The existing opportunities and challenges for successful p53 cancer gene therapy are also discussed.

The Role of Micelle Size in Tumor Accumulation, Penetration, and Treatment.

The specific sizes that determine optimal nanoparticle tumor accumulation, penetration, and treatment remain inconclusive because many studies compared nanoparticles with multiple physicochemical variables (e.g., chemical structures, shapes, and other physical properties) in addition to the size. In this study, we synthesized amphiphilic block copolymers of 7-ethyl-10-hydroxylcamptothecin (SN38) prodrug and fabricated micelles with sizes ranging from 20 to 300 nm from a single copolymer. The as-prepared micelles had exactly the same chemical structures and similar physical properties except for size, which provided an ideal platform for a systematic investigation of the size effects in cancer drug delivery. We found that the micelle's blood circulation time and tumor accumulation increased with the increase in their diameters, with optimal diameter range of 100 to 160 nm. However, the much higher tumor accumulation of the large micelles (100 nm) did not result in significantly improved therapeutic efficacy, because the large micelles had poorer tumor penetration than the small ones (30 nm). An optimal size that balances drug accumulation and penetration in tumors is critical for improving the therapeutic efficacy of nanoparticulate drugs.

Targeting arginine metabolism pathway to treat arginine-dependent cancers.

The significant disparities in metabolism between tumor and normal cells have inspired the development of metabolism-based anti-tumor therapeutics. Arginine is a semi-essential amino acid because normal cells can not only synthesize arginine de novo but also take up extracellular arginine. Several types of tumors have abnormalities in arginine metabolism enzymes and completely rely on extracellular arginine to support necessary biological processes. This property is referred to as arginine auxotrophy. Taking advantage of characteristic arginine auxotrophy in tumors, arginine deprivation, which is generally induced by the use of arginine deiminase (ADI) and arginase I, has been investigated as a novel strategy for cancer therapy. Arginine deprivation demonstrated promising efficacy against arginine-auxotrophic tumors. By integrating perspectives from both clinical oncologists and laboratory scientists, this article reviews the important aspects of arginine deprivation as a promising anticancer therapy.