Regulating intracellular ROS signal by a dual pH/reducing-responsive nanogels system promotes tumor cell apoptosis

Self-Supplied Reactive Oxygen Species-Responsive Mitoxantrone Polyprodrug for Chemosensitization-Enhanced Chemotherapy under Moderate Hyperthermia

Currently, the secondary development and modification of clinical drugs has become one of the research priorities. Researchers have developed a variety of TME-responsive nanomedicine carriers to solve certain clinical problems. Unfortunately, endogenous stimuli such as reactive oxygen species (ROS), as an important prerequisite for effective therapeutic efficacy, are not enough to achieve the expected drug release process, therefore, it is difficult to achieve a continuous and efficient treatment process. Herein, a self-supply ROS-responsive cascade polyprodrug (PMTO) is designed. The encapsulation of the chemotherapy drug mitoxantrone (MTO) in a polymer backbone could effectively reduce systemic toxicity when transported in vivo. After PMTO is degraded by endogenous ROS of the TME, another part of the polyprodrug backbone becomes cinnamaldehyde (CA), which can further enhance intracellular ROS, thereby achieving a sustained drug release process. Meanwhile, due to the disruption of the intracellular redox environment, the efficacy of chemotherapy drugs is enhanced. Finally, the anticancer treatment efficacy is further enhanced due to the mild hyperthermia effect of PMTO. In conclusion, the designed PMTO demonstrates remarkable antitumor efficacy, effectively addressing the limitations associated with MTO.

Maduramicin-guided nanotherapy: A polymeric micelles for targeted drug delivery in canine mammary tumors

Canine mammary tumors (CMT) can severely compromise the life quality of the affected dogs through local recurrence, distant metastases and ultimately succumb to death. Recently, more attention has been given to the potential antimetastatic effect of maduramicin (MAD) on breast cancer. However, its poor aqueous solubility and toxicity to normal tissues limit its clinical application. Therefore, to address the drawbacks of MAD and enhance its anticancer and antimetastatic effects, MAD-loaded TPGS polymeric micelles (MAD-TPGS) were prepared by a thin-film hydration technique. The optimized MAD-TPGS exhibited excellent size distribution, stability and improved water solubility. Cellular uptake assays showed that TPGS polymer micelles could enhance drug internalization. Moreover, TPGS synergistically improved the cytotoxicity of MAD by targeting mitochondrial organelles, improving reactive oxygen species levels and reducing the mitochondrial transmembrane potential. More importantly, MAD-TPGS significantly impeded the metastasis of tumor cells. In vivo results further confirmed that, in addition to exhibiting excellent biocompatibility, MAD-TPGS exhibited greater antitumor efficacy than free MAD. Interestingly, MAD-TPGS displayed superior suppression of CMT metastasis via tail vein injection compared to oral administration, indicating its suitability for intravenous delivery. Overall, MAD-TPGS could be applied as a potential antimetastatic cancer agent for CMT.

pH-responsive bufadienolides nanocrystals decorated by chitosan quaternary ammonium salt for treating colon cancer

Due to its poor prognosis and propensity for metastasizing, colon cancer, a frequent cancer of the gastrointestinal system, has a high morbidity and mortality rate. However, the harsh physiological conditions of the gastrointestinal tract can cause the anti-cancer medicine bufadienolides (BU) to lose some of its structure, impairing its ability to fight cancer. In this study, pH-responsive bufadienolides nanocrystals decorated by chitosan quaternary ammonium salt (HE BU NCs) were successfully constructed by a solvent evaporation method to improve the bioavailability, release characteristics and intestinal transport ability of BU. In vitro, studies have shown that HE BU NCs could improve BU internalization, significantly induce apoptosis, decrease mitochondrial membrane potential, and increase ROS levels in tumour cells. In vivo, experiments showed that HE BU NCs effectively targeted intestinal sites, increased their retention time, and exerted antitumor activity through Caspase-3 and Bax/Bcl-2 ratio pathways. In conclusion, pH-responsive bufadienolides nanocrystals decorated by chitosan quaternary ammonium salt could protect bufadienolides from the destruction of an acidic environment, achieve synergistic release in the intestinal site, improve oral bioavailability, and ultimately exert anti-colon cancer effects, which is a promising strategy for the treatment of colon cancer.

Protective effect of dihydromyricetin on vascular smooth muscle cell apoptosis induced by hydrogen peroxide in rats

OBJECTIVE

Dihydromyricetin (DMY), also called Ampelopsin, which was extracted from Ampelopsis grossedentata, has been demonstrated to have a protective effect against cell oxidative injury and cell apoptosis in vitro. In the present study, we tried to study the role of DMY on apoptosis of vascular smooth muscle cells (VSMCs) induced by hydrogen peroxide (H₂O₂) and explore the underlying mechanisms.

METHODS

Apoptotic cells were detected by Hematoxylin and Eosin (H.E.) staining, Hoechst 33342 staining, and Annexin V-fluorescein isothiocyanate binding assay. The intracellular reactive oxygen species (ROS) level was estimated through fluorescence assay. The mRNA and protein expression of Caspase-3, Caspase-9, Bcl-2, and Bax were determined by reverse transcription-polymerase chain reaction (RT-PCR) and western blot.

RESULTS

The results showed that the pretreatment of VSMCs with DMY not only significantly increased cell viability, reduced intracellular ROS release, alleviated the morphological changes of apoptosis, and decreased the apoptosis rate, but also upregulated Bcl-2 expression and downregulated Caspase-3, Caspase-9, Bax expression, and ultimately attenuated the H₂O₂-stimulated apoptosis.

CONCLUSION

The inhibition of DMY on VSMC apoptosis may be mediated by ROS scavenging and the activation of the mitochondrial apoptotic signaling pathway.

Cinnamaldehyde-Contained Polymers and Their Biomedical Applications

Cinnamaldehyde, a natural product that can be extracted from a variety of plants of the genus Cinnamomum, exhibits excellent biological activities including antibacterial, antifungal, anti-inflammatory, and anticancer properties. To overcome the disadvantages (e.g., poor water solubility and sensitivity to light) or enhance the advantages (e.g., high reactivity and promoting cellular reactive oxygen species production) of cinnamaldehyde, cinnamaldehyde can be loaded into or conjugated with polymers for sustained or controlled release, thereby prolonging the effective action time of its biological activities. Moreover, when cinnamaldehyde is conjugated with a polymer, it can also introduce environmental responsiveness to the polymer through the form of stimuli-sensitive linkages between its aldehyde group and various functional groups of polymers. The environmental responsiveness provides the great potential of cinnamaldehyde-conjugated polymers for applications in the biomedical field. In this review, the strategies for preparing cinnamaldehyde-contained polymers are summarized and their biomedical applications are also reviewed.

α-tocopherol as a selective modulator of toxicogenic damage induced by antineoplastic agents cyclophosphamide and doxorubicin

The aim of this study was to determine the oxidative/antioxidative effects, modulatory and selective potential of α-tocopherol (vitamin E) on antineoplastic drug-induced toxicogenetic damage. The toxicity, cytotoxicity and genotoxicity induced by antineoplastic agents cyclophosphamide (CPA) and doxorubicin (DOX) was examined utilizing as models Saccharomyces cerevisiae, Allium cepa, Artemia salina and human peripheral blood mononuclear cells (PBMCs) in the presence of α-tocopherol. For these tests, concentrations of α- tocopherol 100 IU/ml (67mg/ml), CPA 20 µg/ml, DOX 2 µg/ml were used. The selectivity of α-tocopherol was assessed by the MTT test using human mammary gland non-tumor (MCF10A) and tumor (MCF-7) cell lines. Data showed cytoplasmic and mitochondrial oxidative damage induced by CPA or DOX was significantly diminished by α-tocopherol in S. cerevisiae. In addition, the toxic effects on A. salina and cytotoxic and mutagenic effects on A. cepa were significantly reduced by α-tocopherol. In PBMCs, α-tocopherol alone did not markedly affect these cells, and when treated in conjunction with CPA or DOX, α-tocopherol reduced the toxicogenetic effects noted after antineoplastic drug administration as evidenced by decreased chromosomal alterations and lowered cell death rate. In human mammary gland non-tumor and tumor cell lines, α-tocopherol produced selective cytotoxicity with 2-fold higher effect in tumor cells. Evidence indicates that vitamin E (1) produced anti-cytotoxic and anti-mutagenic effects against CPA and DOX (2) increased higher selectivity toward tumor cells, and (3) presented chemoprotective activity in PBMCs.

pH-sensitive charge-conversion cinnamaldehyde polymeric prodrug micelles for effective targeted chemotherapy of osteosarcoma in vitro

Introduction: Chemotherapy is a common strategy for the treatment of osteosarcoma. However, its therapeutic efficacy is not ideal due to the low targeting, lowbioavailability, and high toxicity of chemotherapy drugs. Nanoparticles can improve the residence time of drugs at tumor sites through targeted delivery. This new technology can reduce the risk to patients and improve survival rates. To achieve this goal, we developed a pHsensitive charge-conversion polymeric micelle [mPEG-b-P(C7-co-CA) micelles] for osteosarcoma-targeted delivery of cinnamaldehyde (CA). Methods: First, an amphiphilic cinnamaldehyde polymeric prodrug [mPEG-b-P(C7-co-CA)] was synthesized through Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) polymerization and post-modification, and self-assembled into mPEG-b-P(C7-co-CA) micelles in an aqueous solution. The physical properties of mPEG-b-P(C7-co-CA) micelles, such as critical micelle concentration (CMC), size, appearance, and Zeta potential were characterized. The CA release curve of mPEG-b-P(C7-co-CA) micelles at pH 7.4, 6.5 and 4.0 was studied by dialysis method, then the targeting ability of mPEG-b-P(C7-co-CA) micelles to osteosarcoma 143B cells in acidic environment (pH 6.5) was explored by cellular uptakeassay. The antitumor effect of mPEG-b-P(C7-co-CA) micelles on 143B cells in vitro was studied by MTT method, and the level of reactive oxygen species (ROS) in 143B cells after mPEG-b-P(C7-co-CA) micelles treatment was detected. Finally, the effects of mPEG-b-P(C7-co-CA) micelles on the apoptosis of 143B cells were detected by flow cytometry and TUNEL assay. Results: An amphiphilic cinnamaldehyde polymeric prodrug [mPEG-b-P(C7-co-CA)] was successfully synthesized and self-assembled into spheric micelles with a diameter of 227 nm. The CMC value of mPEG-b-P(C7-co-CA) micelles was 25.2 mg/L, and it showed a pH dependent release behavior of CA. mPEG-b-P(C7-co-CA) micelles can achieve chargeconversion from a neutral to a positive charge with decreasing pHs. This charge-conversion property allows mPEG-b-P(C7-co-CA) micelles to achieve 143B cell targeting at pH 6.5. In addition, mPEG-b-P(C7-co-CA) micelles present high antitumor efficacy and intracellular ROS generation at pH 6.5 which can induce 143B cell apoptosis. Discussion: mPEG-b-P(C7-co-CA) micelles can achieve osteosarcoma targeting effectively and enhance the anti-osteosarcoma effect of cinnamaldehyde in vitro. This research provides a promising drug delivery system for clinical application and tumor treatment.

Oxidative Stress Amplifiers as Immunogenic Cell Death Nanoinducers Disrupting Mitochondrial Redox Homeostasis for Cancer Immunotherapy

Reactive oxygen species (ROS)-induced oxidative stress in the endoplasmic reticulum (ER) is generally believed to be an important prerequisite for immunogenic cell death (ICD) which can trigger antitumor immune responses for cancer immunotherapy. However, thus far, little is known between the oxidative stress in a certain organelle other than ER and ICD. Herein, polymers for preparing ROS-responsive nanoparticles (NP-I-CA-TPP) with mitochondrial targeting performance as ICD nanoinducers are designed. It is believed that NP-I-CA-TPP can target mitochondria which are extremely important organelles intimately involved in cellular stress signaling to play an important role in the induction of ICD. NP-I-CA-TPP can amplify cinnamaldehyde (CA)-induced ROS damage by iodo-thiol click chemistry-mediated glutathione depletion in cancer cells. Finally, NP-I-CA-TPP is shown to disrupt mitochondrial redox homeostasis, amplify mitochondrial oxidative stress, promote cancer cell apoptosis via inducing ICD, and triggering the body's antitumor immune response for cancer immunotherapy.

The Therapeutic Roles of Cinnamaldehyde against Cardiovascular Diseases

Evidence from epidemiological studies has demonstrated that the incidence and mortality of cardiovascular diseases (CVDs) increase year by year, which pose a great threat on social economy and human health worldwide. Due to limited therapeutic benefits and associated adverse effects of current medications, there is an urgent need to uncover novel agents with favorable safety and efficacy. Cinnamaldehyde (CA) is a bioactive phytochemical isolated from the stem bark of Chinese herbal medicine Cinnamon and has been suggested to possess curative roles against the development of CVDs. This integrated review intends to summarize the physicochemical and pharmacokinetic features of CA and discuss the recent advances in underlying mechanisms and potential targets responsible for anti-CVD properties of CA. The CA-related cardiovascular protective mechanisms could be attributed to the inhibition of inflammation and oxidative stress, improvement of lipid and glucose metabolism, regulation of cell proliferation and apoptosis, suppression of cardiac fibrosis, and platelet aggregation and promotion of vasodilation and angiogenesis. Furthermore, CA is likely to inhibit CVD progression via affecting other possible processes including autophagy and ER stress regulation, gut microbiota and immune homeostasis, ion metabolism, ncRNA expression, and TRPA1 activation. Collectively, experiments reported previously highlight the therapeutic effects of CA and clinical trials are advocated to offer scientific basis for the compound future applied in clinical practice for CVD prophylaxis and treatment.

Multifunctional nanosystems sequentially regulating intratumor Fenton chemistry by remodeling the tumor microenvironment to reinforce chemodynamic therapy

The particularity of the tumor microenvironment (TME) significantly limits the efficiency of chemodynamic therapy (CDT). Although various measures have been taken to improve the efficiency of CDT, how to organically integrate them into one nanosystem to achieve efficient synergy for CDT according to predetermined procedures is still an urgent problem to be solved. This work reported a multifunctional nanosystem, TP_I@PP_CAI, which comprised the inner triphenylphosphine modified D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS-PPh₃) micelles loading iron-oxide nanoparticles (IONs), and the outer poly (dopamine-co-protocatechuic acid) (PDA-PA, PP) coating modified with carbonic anhydrase IX inhibitor (CAI). TP_I@PP_CAI remodeled TME by sequential function adjustment to make it suitable for the efficient Fenton reactions: CAI first inhibited the overexpressed CA IX to result in intracellular acidification, which combined with near-infrared light (NIR) irradiation to accelerate the PP coating degradation, thereby promoting the exposure and disintegration of the inner micellar structure to release TPGS-PPh₃ and IONs. The TPGS-PPh₃ further elevated the intracellular ROS basal level by targeting and interfering with the mitochondrial function. Therefore, the TME was transformed into an acidic microenvironment with high ROS levels, which vigorously promoted the Fenton reaction mediated by IONs with the aid of photothermal effect induced by PP coating via NIR irradiation, ultimately earning high-efficiency CDT on xenograft MDA-MB-231 tumor-bearing mice. This study improved the efficiency of Fenton reaction in biological systems through the practical design of nanostructures and provided a novel thought for ROS-mediated therapy.

Synthesis, characterization and antitumor mechanism investigation of ruthenium(II) polypyridyl complexes with artesunate moiety

Six artesunate (ART) conjugated ruthenium(II) complexes (Ru(II)-ART conjugates) with the formula [Ru(N^N)₂bpy(4-CH₃-4'-CH₂OART)](PF₆)₂ (Ru-ART-1-3) and [Ru(N^N)₂bpy(4-CH₂OART-4'-CH₂OART)](PF₆)₂ (Ru-ART-4-6) (N^N = 2,2'-bipyridine (bpy, in Ru-ART-1 and Ru-ART-4), 1,10-phenanthroline (phen, in Ru-ART-2 and Ru-ART-5) and 4,7-diphenyl-1,10-phenanthroline (DIP, in Ru-ART-3 and Ru-ART-6)), were synthesized and characterized. Among them, Ru-ART-1-3 and Ru-ART-4-6 carry one and two ART moieties, respectively. Ru-ART-3 and Ru-ART-6 exhibit better cytotoxicity among six Ru(II)-ART conjugates. These two complexes can be effectively taken up by human cervical carcinoma (HeLa) cells. In addition, they selectively kill cancer cell lines while mildly affect normal cells. Mechanism studies have shown that HeLa cells treated with Ru-ART-3 and Ru-ART-6 show typical apoptotic characteristics (morphology changes, mitochondrial dysfunction, caspase cascade, etc.). On the other hand, the up regulation of Beclin-1 and conversion of LC3-I to LC3-II note the appearance of autophagy. As a result, Ru-ART-3 and Ru-ART-6 induce autophagy-dependent cell apoptosis via mitochondrial dysfunction and reactive oxygen species (ROS) accumulation. In this work, six artesunate (ART) conjugated ruthenium(II) complexes (Ru(II)-ART conjugates) have been synthesized and characterized. Among them, Ru-ART-3 and Ru-ART-6 exhibit better cytotoxicity. Mechanism studies have shown that HeLa cells treated with Ru-ART-3 and Ru-ART-6 show typical apoptotic characteristics (morphology changes, mitochondrial dysfunction, caspase cascade, etc.). On the other hand, the up regulation of Beclin-1 and conversion of LC3-I to LC3-II note the appearance of autophagy.

Hypoxia-Mediated ROS Amplification Triggers Mitochondria-Mediated Apoptotic Cell Death via PD-L1/ROS-Responsive, Dual-Targeted, Drug-Laden Thioketal Nanoparticles

Amalgamation of the reactive oxygen species (ROS)-responsive stimulus with nanoparticles has gained considerable interest owing to their high tumor specificity. Hypoxia plays a pivotal role in the acceleration of intracellular ROS production. Herein, we report the construction of a cancer cell (PD-L1)- and ROS-responsive, dual-targeted, temozolomide (TMZ)-laden nanosystem which offers a better anticancer effect in a hypoxic tumor microenvironment. A dual-targeted system boosted permeation in the cancer cells. Hypoxic conditions elevating the high ROS level accelerated the in situ release of TMZ from anti-PD-L1-TKNPs. Hyperaccumulated ROS engendered from TMZ caused oxidative damage leading to mitochondria-mediated apoptosis. TMZ fabricated in the multifunctional nanosystem (anti-PD-L1-TMZ-TKNPs) provided excellent tumor accumulation and retarded tumor growth under in vivo conditions. The elevated apoptosis effect with the activation of an apoptotic marker, DNA double-strand breakage marker, and downregulation of the angiogenesis marker in the tumor tissue following treatment with anti-PD-L1-TMZ-TKNPs exerts robust anticancer effect. Collectively, the nanoconstruct offers deep tumor permeation and high drug release and broadens the application of the ROS-responsive nanosystem for a successful anticancer effect.

Galangin Inhibits Gastric Cancer Growth Through Enhancing STAT3 Mediated ROS Production

Galangin, a flavonoid isolated from the rhizome of Alpinia officinarum (Hance), exerts anticancer activities against many cancer cells such as liver cancer, breast cancer, lung cancer and esophageal cancer. However, the effect, as well as the underlying molecular mechanism of galangin on gastric cancer remains to be elucidated. In the present study, galangin inhibited cell viability of MGC 803 cells but not normal gastric mucosal epithelial GES-1 cells. It suppressed cell proliferation accompanied by reduced Ki67 and PCNA expression, promoted apoptosis shown by decreased Bcl-2 and elevated cleaved caspase-3 and cleaved PARP. And, galangin significantly inactivated JAK2/STAT3 pathway. When STAT3 was overexpressed, the proliferation inhibition and apoptosis promotion induced by galangin were abrogated. Meanwhile, galangin increased ROS accumulation, and reduced Nrf2 and NQO-1, but elevated HO-1 in MGC 803 cells. NAC, a ROS scavenger, rescued ROS over-accumulation and proliferation inhibition of galangin. STAT3 overexpression also counteracted excessive ROS accumulation induced by galangin. Consistent with the in vitro experiments, in nude mice exnografted with MGC 803 cells, galangin inhibited tumor growth and reversed the abnormally expressed proteins, such as p-JAK2, p-STAT3, Bcl-2, cleaved caspase-3, cleaved PARP, and Ki67. Taken together, galangin was suggested to inhibit the growth of MGC 803 cells through inducing apoptosis and decreasing cell proliferation, which might be mediated by modulating STAT3/ROS axis. Our findings implicate a potential application of galangin for gastric cancer therapy possibly with low toxicity.

Cinnamaldehyde and Doxorubicin Co-Loaded Graphene Oxide Wrapped Mesoporous Silica Nanoparticles for Enhanced MCF-7 Cell Apoptosis

Background

Combined chemotherapy is often affected by the different physicochemical properties of chemotherapeutic drugs, which should be improved by the reasonable design of co-loaded preparations.

Purpose

A kind of simple but practical graphene oxide (GO) wrapped mesoporous silica nanoparticles (MSN) modified with hyaluronic acid (MSN@GO-HA) were developed for the co-delivery of cinnamaldehyde (CA) and doxorubicin (DOX), in order to enhance their combined treatment on tumor cells and reduce their application defects.

Methods

The MSN_CA@GO_DOX-HA was constructed by MSN_CA (loading CA via physical diffusion) and GO_DOX-HA (modified with HA and loading DOX via π–π stacking) through the electrostatic adsorption, followed by the physicochemical characterization, serum stability and in vitro release study. Cytotoxicity on different cells was detected, followed by the tumor cell uptake tests. The intracellular reactive oxygen species (ROS) changes, mitochondrial functions and activities of caspase-3/-9 in MCF-7 cells were also evaluated, respectively.

Results

The MSN_CA@GO_DOX-HA nanoparticles kept stable in FBS solution and achieved pH-responsive release behavior, which was beneficial to increase the accumulation of CA and DOX in tumor cells to enhance the treatment. MSN_CA@GO_DOX-HA exerted higher cytotoxicity to MCF-7 human breast cancer cells than H9c2 cardiac myocyte cells, which were not only attributed to the active targeting to tumor cells by HA, but also related with the activation of intrinsic apoptotic pathway in MCF-7 cells induced by CA, which was mediated by the specific ROS signal amplification and the interference with mitochondrial function. Moreover, the efficacy of DOX was also enhanced by the above process.

Conclusion

The establishment of the MSN_CA@GO_DOX-HA nanoparticles played a role in promoting strengths and restricting shortcomings of CA and DOX, thereby exerting their function and achieving efficient treatment against cancer.

Homoharringtonine Exerts an Antimyeloma Effect by Promoting Excess Parkin-Dependent Mitophagy

Purpose

Homoharringtonine (HHT) has been used as an antileukemia agent in the clinic which processes a high-potential therapeutic efficacy against multiple myeloma (MM). In this study, we investigated the antimyeloma mechanism of HHT.

Methods

Three MM cell lines and a xenograft model were applied. Mitochondrial function was evaluated by detecting MitoTracker Green, the mtDNA copy number, mitochondrial protein and enzyme activity, the mitochondrial membrane potential and mitochondrial morphology. Mitophagy levels were assessed by monitoring autophagosomes, performing a colocalization analysis and determining the levels of related proteins. An shRNA was applied to knockdown Parkin.

Results

Based on the results of the in vitro experiments, HHT exerted a promising antiproliferative effect on the MM.1S, RPMI 8226 and H929 cell lines by increasing mitophagy. In addition, HHT markedly inhibited myeloma tumor growth and prolonged survival by promoting mitophagy in vivo. Furthermore, HHT treatment contributed to notable mitochondrial dysfunction and Parkin-dependent mitophagy, as evidenced by the destruction of mitochondria, the decrease in the mtDNA copy number, decrease in the Bcl-2/Bax ratio, and decrease in the levels of mitochondrial proteins and the optimal expression of Parkin and NDP52. However, the addition of rapamycin did not produce significant synergistic effect with HHT, indicating that HHT reached the threshold level to induce mitophagy. The colocalization analysis and assessment of mitochondrial function examination further confirmed that HHT triggered mitophagy and mitochondrial dysfunction. Moreover, the antiproliferative effect of HHT was reversed by an shRNA targeting Parkin, highlighting the indispensable role of Parkin-dependent mitophagy in the antimyeloma effect of HHT.

Conclusion

HHT exerts an antimyeloma effect by inducing excess mitophagy, providing new mechanistic insights into a therapeutic strategy for MM.

Modulation of Apoptosis by Plant Polysaccharides for Exerting Anti-Cancer Effects: A Review

Cancer has become a significant public health problem with high disease burden and mortality. At present, radiotherapy and chemotherapy are the main means of treating cancer, but they have shown serious safety problems. The severity of this problem has caused further attention and research on effective and safe cancer treatment methods. Polysaccharides are natural products with anti-cancer activity that are widely present in a lot of plants, and many studies have found that inducing apoptosis of cancer cells is one of their important mechanisms. Therefore, this article reviews the various ways in which plant polysaccharides promote apoptosis of cancer cells. The major apoptotic pathways involved include the mitochondrial pathway, the death receptor pathway, and their upstream signal transduction such as MAPK pathway, PI3K/AKT pathway, and NF-κB pathway. Moreover, the paper has also been focused on the absorption and toxicity of plant polysaccharides with reference to extant literature, making the research more scientific and comprehensive. It is hoped that this review could provide some directions for the future development of plant polysaccharides as anticancer drugs in pharmacological experiments and clinical researches.

Improving tumor hypoxia and radiotherapy resistance via in situ nitric oxide release strategy

Radiation therapy remains one of the main treatments for cancer. However, conventional radiotherapy not only manifests a low radiation accumulation in the tumor site, but also displays numerous negative effects. The most serious clinical problem is the radiotherapy resistance leading to cancer deterioration. As an important gaseous signal molecule, nitric oxide (NO) has been widely studied for its role in regulating angiogenesis, improving hypoxia, and inhibiting tumor growth. However, due to the unstable characteristic, the application of NO in cancer therapy is still limited. Here, we designed a micellar system formed by a NO donor, D-α-Tocopheryl polyethylene glycol 1000 succinate (TPGS)-NO, for enabling sustained NO release to efficiently deliver NO into the tumor area. TPGS-NO could accumulate in the tumor site for extended circulation, thereby releasing NO to exert antitumor effects and enhance radiotherapy effects under low-oxygen conditions. It demonstrated the increased sensitivity of radiotherapy through enhancing tumor angiogenesis appropriately reducing tumor area hypoxia, which significantly induced tumor cell apoptosis and inhibited its repair during radiation. This work may show great potential in synergistic radiotherapy against cancer by facile NO donor administration.