Chitosan in cancer therapy: a dual role as a therapeutic agent and drug delivery system

1 Introduction

Cancer is a disease that seriously threatens life and reduces the quality of life, and cancer-related deaths continue to increase. Anticancer treatment options encompass chemotherapy, radiotherapy, immunotherapy, and surgery, with treatment success contingent on factors such as the stage of diagnosis and the patient’s tolerance. In most cases, chemotherapy stands as the primary choice for treating cancer patients. Still, most chemical agents used in treatment target both cancer cells and healthy cells and reduce therapeutic effectiveness by causing serious side effects due to high toxicity. In addition, resistance to these drugs may occur in the majority of patients in the later stages of treatment. Targeted therapy plays a vital role in enhancing therapeutic efficacy, minimizing undesirable side effects, and distinguishing cancer cells from healthy cells. Food and Drug Administration (FDA)-approved targeted anticancer drugs are used clinically in various types of cancer. In recent years, drug delivery systems have garnered attention due to their potential to enhance the therapeutic efficacy of existing drugs and provide precise and time-controlled delivery, thus promoting safety and targeting in drug administration. These systems offer benefits, including elevated pharmacological activity, mitigation of solubility limitations, enhanced bioavailability, improved biodistribution, and heightened selectivity, while effectively controlling drug absorption, release, and localization. The development of drug delivery systems (DDSs) based on natural polymers has the potential to enhance the effectiveness of current cancer treatments. This approach aims to mitigate the side effects associated with toxic drugs and extend the half-life of medications [1], [2], [3], [4], [5].

Chitosan (CS), a natural heteropolysaccharide derived from chitin (CH), is produced by the deacetylation of CH and contains β-(1–4)-d-glucosamine and N-acetyl-β-(1–4)-d-glucosamine units. CS has a cationic structure and exhibits high solubility in acidic environments and poor solubility in water. The molecular weight of the glucosamine units of CS affects its solubility and biological activity. Amino groups and hydroxyl groups in the CS structure can be modified through chemical reactions such as phosphorylation, quaternization, carboxylation, sulfonation, N-alkylation, and acylation to increase solubility, biocompatibility, and targeting effectiveness, thus CS derivatives are synthesized. CS and its derivatives are widely utilized in cell culture, tissue engineering, biomedical, and pharmaceutical industries due to their various features such as antimicrobial, antibacterial, antioxidant, antifungal, antidiabetic, antiviral, and immune system stimulant. CS is also frequently used in the preparation of hydrogels for drug delivery due to its features such as high drug-carrying capacity, multifunctionality, long-term circulation potential, direct targeting of the cell membrane due to the primary amine groups in its structure, polycationic surface that facilitates the formation of ionic and hydrogenic bonds, high biocompatibility, and biodegradability. Various therapeutic agents conjugated with CS and its derivatives show high anticancer potential with fewer side effects than original drugs due to their superior properties such as cancer-directed distribution and sustainable release. In addition, CS can accumulate at the tumor site and exert an antitumor effect by transforming the immunosuppressive tumor microenvironment into an immune-supportive environment, thus improving the effectiveness of cancer immunotherapy. CS itself exerts an anticancer effect by also inhibiting tumor cell growth, tumor-induced angiogenesis, and tumor metastasis, and CS is also used as a gene carrier in cancer therapy [1], [2], [3], [4], [5], [6].

This review highlights recent research into the synergy between CS and chemotherapeutic agents in drug delivery and the therapeutic potential of CS itself through its ability to inhibit the proliferation of cancer cells.

2 CS as a therapeutic agent in cancer treatment

In cancer treatment studies, biopolymers like biocompatible and biodegradable CS and its derivatives have gained preference as therapeutic agents in recent years due to the inherent drawbacks of conventional anticancer chemotherapeutics, which often result in severe side effects and harm to healthy cells. Numerous studies have been conducted to explore the anticancer properties of CS [4] (Table 1).

Cytotoxic chemotherapeutic agents can induce specific immune responses that result in immunogenic cancer cell death or immunostimulatory side effects [7]. Li and colleagues examined the effect of CS on natural killer cells (NKs) and they have shown that CS increased the antitumor potential of NKs through the activation of dendritic cells (DCs). The study also showed that CS increased the release of IFN-γ from DCs. CS caused activation of STAT4 and NF-κB signaling pathways in NK cells, respectively, by activation of DCs to express proinflammatory cytokines. In vivo experiment results reported that CS stimulated NK cells with in vivo modulation of IL-12 and IL-15 in DCs against B16F10 tumor cells in the mouse melanoma model, as well as increased generation of IFN-γ in NK cells [8]. Ma and colleagues examined the effect of CS on the immunity of lung cancer patients receiving radiotherapy and revealed that CS increased the immunity of cancer patients by increasing the levels of CD3, CD4, CD4/CD8 ratio, NK cells, IL-6, and TNF-α [9].

Recent improvements in cancer treatment notwithstanding, metastasis still stands as the primary reason for cancer-related fatalities [10]. Hence, there is a growing significance in the antimetastatic attributes of cytotoxic agents. Nam et al. evaluated the antimetastatic potential of CS on MDA-MB-231 human breast cancer cells. Exposure of MDA-MB-231 cells to increasing concentrations of CS resulted in decreased cell migration and decreased expression of MMP-9 protein in cancer cells [11].

Gao and colleagues evaluated the anticancer potential of the combination of CS and selenium on lung cancer cells (A549). Research findings displayed that the combination of CS and selenium reduced the viability of A549 cells and induced apoptosis in the cells. Moreover, gene expression analysis results reported that the combination of CS and selenium triggered apoptosis in A549 cells by up-regulating the expression levels of Fas, FasL, and Fadd [12].

Wu and colleagues designed a seleno-short chain CS derivative and investigated its cytotoxicity on breast cancer MCF-7 and BT-20 cells. Research findings reported that seleno-short chain CS exerts a cytotoxic effect on breast cancer cells and induces apoptosis. Gene expression analysis revealed that seleno-short-chain CS triggers apoptosis in cancer cells via the mitochondrial pathway by up-modulating BAX expression and down-modulating Bcl-2 expression [13]. In another study, Wu and colleagues examined the anticancer effect of seleno-short chain CS on lung cancer cells (SPC-A-1). Seleno-short chain CS exhibited a cytotoxic effect by inhibiting the growth of SPC-A-1 cells with increasing time and concentration. Additionally, seleno-short chain CS triggered apoptosis in cancer cells via the mitochondrial pathway, and MALDI-TOF MS results suggested that 15 proteins associated with the Fas/FasL pathway were abnormally expressed [14].

Angiogenesis plays a crucial role in cancer development, facilitating the supply of oxygen, nutrients, and growth factors, as well as the potential spread of tumors to distant organs. Inhibiting angiogenesis stands as a vital strategy to prevent various solid tumors that rely on cutting off or reducing the blood supply to tumor microregions, leading to widespread hypoxia and necrosis within solid tumor tissues. These drugs constitute a critical component of treatment for certain cancer types [15]. Jiang and colleagues tested the antitumor angiogenesis effects of carboxymethyl CS on mouse hepatocarcinoma 22 (H22) cells. Research findings reported that carboxymethyl CS significantly suppressed the migration of endothelial cells (HUVEC) and the growth of mouse hepatocarcinoma 22 cells. Also, H22 tumor CD34 expression in cells, vascular endothelial growth factor level in serum, and tissue inhibitor levels of metalloproteinase 1 were modulated by carboxymethyl CS treatment. In summary, it was determined that carboxymethyl CS exhibited antitumor effects by blocking tumor angiogenesis and triggering immune functions [16]. In another study, a new CS derivative was synthesized by modifying the sulfates and phenyls in carboxymethyl benzylamide dextrans with CS, and its anticancer activity on breast cancer cells was examined. CS derivatives blocked cell proliferation of MCF-7 and MDA-MB-231 cells, triggering apoptosis, and inhibited FGF-2-triggered phosphorylation of ERK in MCF-7 cells [17].

Wimardhani and colleagues investigated the anticancer effect of CS and cisplatin in oral squamous cell carcinoma (SCC) Ca9-22 and noncancer keratinocyte HaCaT cell lines. Although cisplatin exhibited a cytotoxic effect in both cell lines, CS showed a cytotoxic effect only in the Ca9-22 cell line. An increase in caspase expression occurred in Ca9-22 cells treated with CS, resulting in G1/S cell cycle arrest [18].

Abedian and colleagues tested the cytotoxic effect of high molecular weight and low molecular weight CS on MCF-7, HeLa, and Saos-2 cancer cell lines. CS derivatives showed a significant cytotoxic effect in all three cancer cell lines and inhibited the growth of cancer cells. While necrosis-type death occurred in MCF-7 cells, apoptosis-type cell death was detected in Saos-2 and HeLa [19].

Inappropriate apoptosis, either insufficient or excessive, is closely tied to the development of various diseases. In cancer, inadequate apoptosis leads to the rapid proliferation of malignant cells. Any disruptions in apoptotic pathways can result in cell transformation, tumor metastasis, and resistance to anticancer drugs [20]. Gibot and colleagues investigated the apoptotic effects of CS and the anticancer potential of CS in A375, SKMEL28, and RPMI7951 cell lines. CS reduced the adhesion of the A375 cell line and the proliferation of the SKMEL28 cell line and exhibited a strong proapoptotic effect in the RPMI7951 cell line. CS triggered apoptosis by causing the up-regulation of proapoptotic molecules and down-regulation of antiapoptotic proteins. Furthermore, treatment with CS resulted in the exposure of a large number of CD95 receptors on the surface of RPMI7951 cells, making them more susceptible to FasL-induced apoptosis [21].

Chen and colleagues evaluated the anticancer effect of O-benzoylselenoglycolic CS with high selenium concentration in the HepG2 cell line. The results reported that CS had a significant cytotoxic effect on the cancer cell line, but had no such effect on normal cells. Moreover, it was suggested that O-benzoylselenoglycolic CS could trigger early apoptosis, G2/M, S phase arrest, and activation of caspase-3 activity to block the growth of the HepG2 cell line [22].

Zheng and colleagues examined the antitumor potential of carboxymethyl CS in both normal cell L02 and three tumor cell lines (Bel-7402, SGC-7901, and Hela). While carboxymethyl CS improved TGF-α secretion of L02 cells, it reduced the levels of transforming growth factor alpha (TGF-α) and vascular endothelial growth factor (VEGF) secreted by Bel-7402 cells. In vivo carboxymethyl CS blocked the growth of sarcoma 180 in mice and increased body immunity by increasing serum IL-2 and TNF-α levels [23].

Dou et al. reported that CS-exposed HL-60 cells exhibited increased cleavage of poly (ADP-Ribose) polymerase PARP and p21 expression along with G0/G1 cell cycle arrest. CS up-modulated the expression of proapoptotic molecules Fas, FADD, and Bax in the HL-60 cell line, while significantly decreasing the expression of antiapoptotic Bcl-2. Additionally, CS was found to increase galectin-9 mRNA expression, and overexpression of galectin-9S or galectin-9L was reported to substantially boost the CS-induced apoptotic rate in HL-60 cells [24].

Alongside in vitro research, there are in vivo studies delving into the anticancer properties of CS. Fernandes and colleagues evaluated the therapeutic potential of CS oligosaccharides in a rat urinary bladder carcinogenesis model. It was found that high concentrations of CS oligosaccharides (500 mg/kg b.w.) may have a preventive potential in the development of bladder cancer and a curative effect on established bladder tumors, but this was attributed to secondary effects such as hypercholesterolemia and hypertriglyceridemia. Low doses (50 and 250 mg/kg b.w.) provided only a therapeutic effect. It has been reported that this antitumor effect may be due to mechanisms that are not directly dependent on COX-2 inhibition, such as control of cellular proliferation and improvement of the antioxidant profile, in addition to its anti-inflammatory effect [25].

Shen and colleagues studied the antitumor and antimetastatic effect of CS oligosaccharides in HepG2 cells and found that CS oligosaccharides reduced the rate of DNA synthesis and suppressed cell proliferation by reducing the percentage of S phase in HepG2 cells. Gene expression analysis reported that p21 was up-modulated and PCNA, cyclin A, and CDK-2 were down-modulated, and the activity of the metastatic associated protein (MMP-9) was found to be blocked by CS oligosaccharides in Lewis lung carcinoma (LLC) cells. CS oligosaccharides blocked tumor growth of HepG2 xenografts in severe combined immunodeficiency (SCID) mice. CS oligosaccharides reduced tumor growth, number of lung colonies, and lung metastasis in mice bearing LLC, improving the survival of LLC mice [26].

Liu and colleagues evaluated the cytotoxic potential of CS oligosaccharides in human hepatoma cells. CS oligosaccharides dose-dependently blocked the growth of cells and triggered apoptosis by decreasing Bcl-2 expression and increasing caspase-3 expression level. The research findings were an important precursor to the clinical development of CS oligosaccharide as an antihepatoma drug [27].

Tan and colleagues showed that CS induces osteoblast proliferation and osteogenesis in mesenchymal stem cells, increases osteopontin and collagen I expression, and decreases osteoclastogenesis. CS blocked the invasion of endothelial cells by down-modulating uPA/R, MT1-MMP, CDC42, and Rac1 and triggered apoptosis in the prostate (PC3) and breast cancer cells (MDA-MB-231) through caspase-2 and -3 activation and prevented their formation in bone [28].

Jing and colleagues evaluated the antitumor and antimetastatic potential of acetylated CS oligosaccharides on liver cancer cells. Acetylated CS oligosaccharides significantly blocked the proliferation of HepG2 cells and blocked the migration of HepG2 cells by suppressing pseudopod creation in liver tumor cells, while also reducing the number of liver tumor cells adhering to the surface of the HUVEC layer [29].

Luo and colleagues investigated the antimetastatic potential of CS oligosaccharides in SGC-7901 gastric cancer cells and found that CS oligosaccharides significantly suppressed SGC-7901 cell proliferation and metastasis in a dose-dependent manner. Additionally, CS oligosaccharides were reported to have an antimetastatic effect on cancer cells by reducing CD147 and MMP2 expression levels [30].

Chen and colleagues reported that glycated CS reduced the motility and invasion of breast cancer cells both in vitro and in vivo. Lung metastatic rates decreased when treatment of 4T1 tumor-bearing mice with glycated CS combined with local high-intensity focused ultrasound treatment. Moreover, after the combined treatment of glycated CS and local high-intensity focused ultrasound, macrophage accumulation occurred in tumor lesions, which stimulated the immune system to fight cancer cells. Outcomes exhibited that glycated CS diminished the expression of Twist-1 and Slug, proto-oncogenes that play a role in metastasis [31].

Kim and colleagues tested the potential anticancer activity of CS in human leukemia cells (U937, K562, HL60, and THP-1). CS suppressed cell proliferation and triggered apoptosis via the mitochondria-dependent pathway in all leukemic cells, an effect mediated by a significant increase in caspase activation and cleavage of poly(ADP-ribose) polymerase. Additionally, CS reduced the level of Bcl-2 expression in leukemic cells and suppressed cell proliferation by blocking the phosphorylation of Akt [32].

3 CS as a drug delivery in cancer treatment

CS and CS derivatives are also preferred as drug carriers in cancer treatment due to their properties that can increase drug absorption, stabilize drug components, and increase drug release. Conjugates of various anticancer agents with CS and its derivatives show a predominant distribution in the cancer site and can gradually release the drug from the conjugate, thus showing a higher anticancer effect with fewer side effects than its original form [4]. Recent research has demonstrated that the integration of nanotechnology with CS and its derivatives has the potential to overcome drug transport challenges, ultimately enhancing drug effectiveness (Table 2).

Zhu and colleagues designed T7 peptide-modified nanoparticles (T7-CMCS-BAPE, CBT) based on carboxymethyl chitosan (CMCS) that can target and bind to the transferrin receptor (TfR) expressed in lung cancer cells (A549) and adjust drug release according to pH value and ROS level. Designed complexes showed higher anticancer effects than Docetaxel monotherapy and other nanocarriers loaded with Docetaxel and Curcumin alone. In addition, CBT-DC inhibited tumor cells by promoting the immunosuppressive microenvironment [33].

Yang and colleagues designed the conjugation of hyaluronic acid (HA) and fluorescein isothiocyanate (FI) after modifying carboxymethyl chitosan (CMC) with graphene oxide (GO). Doxorubicin (DOX)-loaded GO-CMC-FI-HA conjugate (GO-CMC-FI-HA/DOX) specifically targeted Hela cancer cells overexpressing CD44 receptors and blocked their growth [34].

Manivasagan and colleagues synthesized gold nanoparticles (AuNPs) using chitosan oligosaccharides (COS) and then loaded them with paclitaxel (PTX). PTX-COS AuNPs showed effective cytotoxicity on MDA-MB-231 by triggering apoptosis through ROS formation and altered mitochondrial membrane potential (MMP) level [35].

Liu and co-workers generated 5-fluorouracil (5-FU)-loaded mesoporous silica nanoparticle (MSN-NH2) based on galactosylated chitosans (GCs). 5-FU-MSN-NH2/GC exhibited significantly higher cytotoxicity than 5-FU-MSN-NH2 and free 5-FU in human colon cancer cells (SW620), triggering apoptosis in the cells. Outcomes reported that MSN-NH2/GC exerted these effects by specifically recognizing and binding to cancer cells by targeting the galectin receptor [36].

Wang and colleagues designed HER2 antibody-decorated nanoparticles assembled from aldehyde hyaluronic acid (AHA) and hydroxyethyl chitosan (HECS) and loaded them with DOX and cisplatin. Research findings reported that this nanoplatform loaded with DOX and cisplatin showed a synergistic anticancer effect in MCF-7 cells, indicating that this nanoplatform could be a pioneer for combined chemotherapy studies in breast cancer [37].

Ataabadi and colleagues tested the antitumor and antiangiogenic effects of enoxaparin-coated dacarbazine-loaded chitosan nanoparticles (Enox-Dac-Chi NPs) in melanoma cells (B16F10). Enox-Dac-Chi NP showed a higher antitumor effect in melanoma cells than CS nanoparticles containing dacarbazine alone (Dac-Chi NPs) and free dacarbazine. Additionally, Enox-Chi NP showed a greater antiangiogenic effect compared to enoxaparin, which means that metastasis of melanoma cells can be prevented [38].

Agrawal and colleagues designed DOX-loaded d-α-tocopherol polyethylene glycol 1000 succinate conjugated chitosan (TPGS-chitosan) nanoparticles. DOX-loaded chitosan nanoparticles, both targeting and nontargeting the transferrin receptor, exhibited a cytotoxic effect on C6 glioma cells. Moreover, the results revealed that both DOX-loaded nanoparticles targeting and nontargeting the transferrin receptor exhibited a significantly higher antitumor effect on cancer cells compared to DOX alone [39].

Irani et al. loaded temozolomide (TMZ) into chitosan (CS) nanoparticles and incorporated the synthesized CS/TMZ nanoparticles into synthesized poly (ε-caprolactone diol)-based polyurethane nanofibers (PCL-Diol-b-PU). Following this, the researchers synthesized gold nanoparticles and used them to coat the surface of CS/TMZ-loaded nanofibers. Research findings demonstrated that gold-coated CS/TMZ-loaded PCL-Diol-b-PU nanofibers significantly suppressed the growth of U-87 glioblastoma cells [40].

Zhong and colleagues designed a polymeric micelle utilizing doxorubicin (DOX)-conjugated trimethyl-chitosan (TMC) with Beclin-1 siRNA (Si-Beclin1/DOX-TMC). Si-Beclin1/DOX-TMC micelle showed an antitumor effect in drug-sensitive BIU-87 cells and drug-resistant BIU-87/ADR bladder cancer cells; The mechanism underlying micellin reversal of drug resistance in BIU-87/ADR cells appeared to be associated with up-regulation of autophagy levels [41].

Zamanvaziri and colleagues designed chitosan (CS) nanocomplex (polyethylene glycol (PEG)-folic acid (FA)-Sb-CS) and loaded sodium butyrate (Sb), an antitherapeutic agent, into it. PEG-CS-FA-Sb conjugate exhibited a significant antitumor effect in PC3 and DU145 prostate cancer cells, and a significant increase in both apoptotic and autophagic gene expression levels (caspase-9, BAX, ATG5, BECLIN1, mTORC1) occurred in DU145 cells [42].

Al-Ali and colleagues designed chitosan iron oxide nanoparticles (CS-IONPs) as a carrier for the leukemia anticancer drug chlorambucil (Chloramb). The cytotoxic effects of CS-IONPs and Chloramb-CS-IONP nanocomposite were investigated on leukemia cancer cell lines (WEHI). It was determined that Chloramb-CS-IONP nanocomposite showed a higher anticancer effect on cancer cells than the free form of Chloramb [43].

Liang Ye and colleagues designed folate-conjugated and chitosan-coated doxorubicin nanoparticles (FA-CS-DOX). FA-CS-DOX nanoparticles exhibited more effective cytotoxicity in HepG2 liver cancer cells compared to CS-DOX. FA-CS-DOX conjugate triggered apoptosis by increasing P53 expression in HepG2 cells and stopped the cell cycle in the G2/M phase [44].

Kim and colleagues designed a liposomal glycol chitosan (GC) formulation and loaded doxorubicin (DOX) and rapamycin (RAPA) into it. GC-DOX/RAPA ω-liposomes were found to have high loading efficiency for both DOX and RAPA. GC-DOX/RAPA ω-liposomes exhibited both synergistic anticytotoxic effects and pH-responsive drug release in DOX-resistant MDA-MB-231 cells [45].

Muddineti and colleagues designed cholesterol-modified chitosan as a carrier for siRNA and curcumin, a chemotherapeutic agent. SiRNA/curcumin-loaded nanoparticles (C-CCM/siRNA) were significantly internalized by lung carcinoma cells A549 in a time-dependent manner. Research findings gave clues that cholesterol-modified chitosan can be used as a drug carrier that can be utilized in siRNA and combination cancer treatment [46].

Ayyanaar and colleagues evaluated the cytotoxic effect of Fe₃O₄@OA-CS-5-FLU-NPs, which they designed as drug carriers, in A549 and HelaS3 cells. Fe₃O₄@OA-CS-5-FLU-NP exhibited a significant cytotoxic effect on A549 and HeLa S3 cancer cells and induced the inhibition of tumor cells. IC50 values ​​at the 24th hour were calculated as 12.9 and 23 μg/mL, respectively [47].

Jiang and colleagues synthesized biodegradable chitosan hollow nanospheres (CHN) and loaded them with the lung cancer drug paclitaxel (PTX). PTX-CHN was successfully internalized by A549 cells and displayed a significant cytotoxic effect on lung cancer cells, inhibiting their growth and triggering apoptosis. It was also observed that CHN was biodegradable in cells [48].

Yoo and colleagues synthesized a formulation named GC10/DOX based on visible light-cured glycol chitosan (GC) hydrogel and doxorubicin⋅hydrochloride (DOX⋅HCl) and evaluated its cytotoxic potential on thyroid cancer cells (FTC-133). In vitro results revealed that GC10/DOX exhibited a stronger cytotoxic effect on thyroid cancer cells compared to free DOX⋅HCl and GC10 hydrogel controls. In vivo results also reported that local injection of GC10/DOX near tumor tissue showed a stronger antitumor effect compared to free DOX⋅HCl and GC10 hydrogel controls [49].

Skorik and colleagues synthesized two chitosan-based nanoparticles named N-succinyl-chitosan (SC) and N-glutaryl-chitosan (GC) and loaded them with taxanes (paclitaxel and docetaxel). Taxane-loaded SC and GC nanoparticles showed significantly strong cytotoxicity on AGS cancer cell lines, and the antitumor effect of the nanoparticles was found to be higher compared to free taxanes [50].

In another study, indomethacin, 5-FU, and curcumin were entrapped one by one in Eudragit RS NPs utilizing nanoprecipitation and incorporated in biphasic chitosan/HPMC microcapsules (MCs) utilizing aerosolization. Drug-loaded NPs significantly suppressed the proliferation of human colon adenocarcinoma HT-29 cells compared to free drugs. The results revealed that NPs may be a significant vehicle for delivering drugs to the colon for aggregation in tumors [51].

Tran and colleagues synthesized a chitosan-coated lipid nanocapsule (ART-CLN) and loaded artesunate (ART), a hydrophobic antimalarial agent, into it. High drug entrapment and release profiles were detected in the synthesized nanoparticles. ART-CLN had a stronger antitumor effect than free ART in MCF-7 and MDA-MB-231 breast cancer cells. Experimental findings reported that loading ART into nanoparticles could strongly enhance the activity and physical stability of ART in cancer treatment [52].

Meng and colleagues designed O-carboxymethyl chitosan/perfluorohexane (O-CS NDs) and doxorubicin-loaded O-carboxymethyl chitosan conjugates. O-CS NDs obtained improved tumor cellular associations at acidic pH due to strong serum stability, pH-dependent charge conversion, and strong ultrasound imaging activity. Doxorubicin-loaded O-carboxymethyl chitosan conjugates showed an excellent cytotoxic effect on PC-3 cells when exposed to ultrasound [53].

Hefnawy and colleagues first combined the antichemotherapeutic DOX with negatively charged carboxymethyl chitosan-g-poly(acrylate) and then coated this complex with a pair of positively charged ligands (lactobionic acid and glycyrrhetinic acid)-conjugated chitosan. DOX-loaded dual ligands-decorated core/shell nanoparticles increased the intracellular uptake of the drug by 4-fold and 8-fold after 4 h and 24 h of incubation, respectively. Nanoparticles showed a safer and higher antitumor effect compared to free DOX on Wistar rats with induced liver tumors (HepG2) [54].

Zavareh and colleagues designed the 5-fluorouracil-chitosan-carbon quantum dot-aptamer (5-FU-CS-CQD-Apt) nanoparticles and evaluated their effects on breast cancer cells. The results revealed that the 5-FU-CS-CQD-Apt nanoparticle released the drug in a controlled manner and inhibited the growth of tumor cells. Gene expression analysis reported that the Bcl-2/Bax ratio diminished after treatment with 5-FU-CS-CQD-Apt in MCF-7 cells [55].

Garcia and colleagues synthesized docetaxel-loaded anionic nanoliposomes coated with a mucoadhesive chitosan layer. Although empty liposomes and chitosans did not exhibit cytotoxic effects on human laryngeal stroma and cancer cells, docetaxel-loaded chitosans showed stronger cytotoxicity on human laryngeal cancer cells (LSCC) than human stromal cells and control treatments [56].

Parsian and colleagues synthesized chitosan-coated iron oxide nanoparticles (CsMNPs) and tested their cytotoxic effect on the human breast cancer cell lines MCF-7 and SKBR-3. The IC50 value of Gem-CsMNPs was calculated to be 1.4-fold and 2.6-fold lower than that of free Gem in SKBR-3 and MCF-7 cell lines; this demonstrated the increased efficacy of gemcitabine when loaded into nanoparticles [57].

Chi and colleagues developed norcantharidin-conjugated carboxymethyl chitosan (CMCS-NCTD) to enhance the antitumor activity of Norcantharidin (NCTD), an important antitumor compound with potent nephrotoxicity. CMCS-NCTD suppressed the migration of A549 tumor cells in a dose-dependent manner both in vitro and in vivo. CMCS-NCTD also suppressed tumor angiogenesis by modulating the expressions of VEGF, MMP-9, and TIMP-1 [58].

Sadeghzadeh and colleagues synthesized PLGA-based nanosystems (COL-PPCF-NP) modified with PEG, chitosan, and folic acid and combined it with colchicine to evaluate its potential in cancer cells. COL-PPCF-NPs showed an antioxidant effect by blocking ABTS and DPPH free radicals and induced apoptosis by showing a selective cytotoxic effect in HT-29 cancer cells compared to HFF cells [59].

Nisar and colleagues synthesized glutamic acid-grafted chitosan (CH-g-GA) hydrogel beads and loaded them with (Doxorubicin, Dox). The highest drug release (81.33 % at 144 h) was detected at pH 5.8, and Dox-loaded beads exhibited significant cytotoxicity against MCF-7 breast cancer cells compared to HEK-293 cells [60].

Ahmadi Nasab and colleagues coated mesoporous silica nanocarriers with chitosan and loaded them with curcumin. This nanocarrier was developed to improve both the anticancer features and solubility of curcumin in U87MG glioblastoma cancer cells. Cell viability testing reported the IC50 after 72 h of exposure with free curcumin and curcumin-loaded CS-MCM-41 to be 15.20 and 5.21 μg/mL, respectively [61].

Zeng and colleagues developed the celastrol (Cel)-chitosan oligosaccharide (CSO) conjugate to overcome the low water solubility of celastrol, an antitumor drug candidate. Cel-CSO, containing ∼10 wt% of celastrol, exhibited stronger aqueous solubility (18.6 mg/mL) than parent celastrol. Cel-CSO substantially blocked tumor growth in pancreatic cancer cells (BxPC-3), triggering apoptosis and inhibiting metastasis [62].

Afkham and colleagues developed chitosan/CMD nanoparticles for the encapsulation of anticancer drugs SN38 and SNAIL-specific siRNA. Outcomes ensured the argument for the offer that, ChNP-CMD-SN38-siRNA treated cells, the mRNA level of snail reduced from 1.00 to 0.30 (±0.14) and 0.09 (±0.04) after 24 h and 48 h, respectively. Moreover, the fold induction of E-cadherin and Claudin-1 boosted from 1.00 to now 3.12 (±0.62), 3.02 (±0.28) after 24 h and 5.6 (±0.91), 4.42 (±0.51) after 48 h, respectively. Finally, the delivery of SN38 and Snail-specific siRNA together with chitosan nanoparticles suppressed the survival and migration of PC-3 cells [63].

Obaidy and colleagues designed a drug carrier by coating superparamagnetic iron oxide nanoparticles (SPIONs) with paclitaxel (PTX)-loaded chitosan (CS) and polyethylene glycol (PEG), and this nanosystem was functionalized by receptors targeting folate (FA). In vitro, study results revealed that SPION@CS-PTX-PEG-FA suppressed the proliferation and induced apoptosis of BALB/c mouse fibrosarcoma cells (WEHI-164). In vivo findings suggested that SPION@CS-PTX-PEG-FA reduced tumor size, caused longer survival, improved splenocyte proliferation and IFN-γ level, and reduced IL-4 level compared to free PTX and control specimens [64].

4 CS-based biomimetic materials for cancer treatment

CS-based biomimetic materials are designed and engineered to mimic certain aspects of the biological environment, structures, or functions found in living organisms. In the context of cancer, CS-based biomimetic materials are used for various purposes related to cancer detection, diagnosis, and treatment [65]. In addition to their use as DDS, they have also been used in the field of cancer as imaging agents, targeted therapy, tissue engineering, and diagnostic tools. CS-based materials can be modified to carry imaging agents, enabling better visualization of cancer cells or tumors in diagnostic imaging techniques such as magnetic resonance imaging (MRI) or positron emission tomography (PET). Biomimetic materials can be engineered to mimic the specific features of cancer cells, allowing for targeted drug delivery to cancerous tissues while minimizing the impact on healthy cells. This can enhance the therapeutic effects and reduce side effects. CS-based biomimetic materials may be used in tissue engineering applications to create scaffolds or matrices that support the growth and development of artificial tissues for cancer research, drug testing, or even regenerative medicine. They can be incorporated into diagnostic tools for cancer detection. For example, they may be used in biosensors or other detection devices to identify cancer-specific biomarkers or detect circulating tumor cells. They can be designed to have photothermal properties, allowing them to absorb light and convert it into heat. This can be utilized for photothermal therapy, a technique where targeted cancer cells are heated to destroy them [66, 67].

Research in this field is ongoing, and scientists are continually exploring new ways to leverage the unique properties of chitosan-based biomimetic materials for improved cancer diagnosis and treatment. The use of biomimetic approaches aims to enhance the compatibility of materials with biological systems and improve their efficacy in addressing the challenges associated with cancer.

5 Conclusions

Challenges including chemotherapeutic agent resistance, severe side effects, and harm to healthy cells have prompted the emergence of novel therapeutic agents and drug delivery systems. CS and its derivatives have attracted the attention of cancer investigators as both potential therapeutic agents and potential drug carriers due to their excellent features such as biodegradability, biocompatibility, and low toxicity. CS and its derivatives can hinder the proliferation of cancer cells as a therapeutic agent and target cancer cells as a drug carrier in the delivery of genes such as siRNA and chemotherapeutic drugs such as docetaxel and paclitaxel. For the clinical use of CS and its derivatives, further research is needed, such as optimizing drug loading and release properties and elucidating the mechanisms underlying antitumor effects.