Just getting into cells is not enough: mechanisms underlying 4-(N)-stearoyl gemcitabine solid lipid nanoparticle's ability to overcome gemcitabine resistance caused by RRM1 overexpression

A first-in-class inhibitor of homologous recombination DNA repair counteracts tumour growth, metastasis and therapeutic resistance in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is among the cancer types with poorest prognosis and survival rates primarily due to resistance to standard-of-care therapies, including gemcitabine (GEM) and olaparib. Particularly, wild-type (wt)BRCA tumours, the most prevalent in PDAC, are more resistant to DNA-targeting agents like olaparib, restraining their clinical application. Recently, we disclosed a monoterpene indole alkaloid derivative (BBIT20) as a new inhibitor of homologous recombination (HR) DNA repair with anticancer activity in breast and ovarian cancer. Since inhibition of DNA repair enhances the sensitivity of cancer cells to chemotherapy, we aimed to investigate the anticancer potential of BBIT20 against PDAC, particularly carrying wtBRCA.

METHODS

In vitro and in vivo PDAC models, particularly human cell lines (including GEM-resistant PDAC cells), patient-derived organoids and xenograft mice of PDAC were used to evaluate the anticancer potential of BBIT20, alone and in combination with GEM or olaparib. Disruption of the BRCA1-BARD1 interaction by BBIT20 was assessed by co-immunoprecipitation, immunofluorescence and yeast two-hybrid assay.

RESULTS

The potent antiproliferative activity of BBIT20, superior to olaparib, was demonstrated in PDAC cells regardless of BRCA status, by inducing cell cycle arrest, apoptosis, and DNA damage, while downregulating HR. The disruption of DNA double-strand breaks repair by BBIT20 was further reinforced by non-homologous end joining (NHEJ) suppression. The inhibition of BRCA1-BARD1 heterodimer by BBIT20 was demonstrated in PDAC cells and confirmed in a yeast two-hybrid assay. In GEM-resistant PDAC cells, BBIT20 showed potent antiproliferative, anti-migratory and anti-invasive activity, overcoming GEM resistance by inhibiting the multidrug resistance P-glycoprotein, upregulating the intracellular GEM-transporter ENT1, and downregulating GEM resistance-related microRNA-20a and GEM metabolism enzymes as RRM1/2. Furthermore, BBIT20 did not induce resistance in PDAC cells. It inhibited the growth of patient-derived PDAC organoids, by inducing apoptosis, repressing HR, and potentiating olaparib and GEM cytotoxicity. The enhancement of olaparib antitumor activity by BBIT20 was confirmed in xenograft mice of PDAC. Notably, it hindered tumour growth and liver metastasis formation, improving survival of orthotopic xenograft mice of PDAC. Furthermore, its potential as a stroma-targeting agent, reducing fibrotic extracellular matrix and overcoming desmoplasia, associated with an enhancement of immune cell response by depleting PD-L1 expression in tumour tissues, renders BBIT20 even more appealing for combination therapy, particularly with immunotherapy.

CONCLUSION

These findings underscore the great potential of BBIT20 as a novel multifaceted anticancer drug candidate for PDAC treatment.

Solid lipid nanoparticles in pancreatic cancer treatment

Pancreatic cancer comes with one of the poorest prognoses of all cancers and as such it is crucial that new therapies are developed to improve on the current statistics. Currently, chemotherapy is the cornerstone of pancreatic cancer treatment with several drugs, and combinations of drugs being utilised for their anti-cancer effect. However, pancreatic cancer has a dense stroma around the tumour and intratumoral bacteria which result in drugs having difficulty penetrating the tumour or being metabolised by bacteria rendering them inactive. The utilisation of nanotechnology in chemotherapy for pancreatic cancer has been a huge area of focus for researchers worldwide with most of the focus being on lipid-based, inorganic and polymer-based nanoparticles. Solid lipid nanoparticles which have been studied since being first published in the 1990s, have been poorly researched for pancreatic cancer applications. Being composed of physiological lipids, solid lipid nanoparticles offer a greatly reduced risk of acute or chronic toxicities arising compared to inorganic or polymeric nanoparticles. They also possess the ability to improve on circulation time, permeability, and bioavailability of many first-line chemotherapeutics.

Validation of ZIP4 as a tumour-associated antigen for nanotargeting

Pancreatic ductal adenocarcinoma remains a highly aggressive and untreatable cancer. There is a need to develop a new PDAC-associated antigen-targeting drug delivery system to tackle this disease. We validated choosing ZIP4 as a putative target in PDAC theranostics. We developed a nanosystem composed of a fluorescent polystyrene core coated with gold nanoparticles onto which a ZIP4-specific polyclonal antibody is attached. The polystyrene core's fluorescence properties allow the nanosystem tracking by intravital imaging. We also developed two ZIP4-expressing cell lines by stably transfecting HEK293 and RWP1 cells with a ZIP4-coding plasmid that simultaneously provides cells with puromycin resistance. We studied the cell internalisation of the as-synthesised nanoparticles and demonstrated that ZIP4-expressing HEK293 and ZIP4-expressing RWP1 cells tended to take up more ZIP4-targeting nanoparticles. Moreover, we observed that ZIP4-targeting nanoparticles accumulated more in ZIP4-expressing HEK293 and RWP1 tumours when injected intravenously in a subcutaneous xenograft and an orthotopic in vivo model, respectively. Furthermore, the administration of these nanoparticles did not induce any significant systemic toxicity as determined by histological analysis of all organs. Altogether, these results provide the first evidence of the feasibility of using a ZIP4-targeting nanosystem further to design efficient therapeutic and diagnostic tools for PDAC.

Improved Antitumor Efficiency of N4 -Tetradecyloxycarbonyl Gemcitabine-Loaded Liposomes for Pancreatic Cancer Chemotherapy

Background

Gemcitabine (Gem) is one of the first-line chemotherapy drugs for pancreatic cancer treatment. However, its short half-life in plasma and adverse effects limited its broader application.

Methods

A novel Gem derivative (N4 -tetradecyloxycarbonyl gemcitabine, tcGem) was synthesized and encapsulated into liposomes (LipotcGem) to overcome the above shortcomings.

Results

LipotcGem has been successfully formulated, with the average size of 115 nm, zeta potential values of -36 mV, encapsulation efficiency of up to 98%, and drug loading capacity of 8.1%. Compared to Gem, LipotcGem improved in vitro antitumor activity significantly, as evidenced by the lower IC50, the higher percentage of apoptotic cells, the stronger ability to inhibit cell migration and invasion due to the higher cellular accumulation (100 times). Additionally, the endocytosis of LipotcGem was mainly mediated by caveolae, and was then processed in the lysosome, where tcGem was released and hydrolyzed into Gem. LipotcGem inhibited tumor growth by 70% in subcutaneous xenograft model and 90% in orthotopic xenograft model, respectively. LipotcGem suppressed tumor metastasis and prolonged survival without perceptible systemic toxicity, which may be caused by the longer t1/2 in vivo (3.5 times, 5.23 vs 1.46 h) and more enrichment in tumor tissue (750 times).

Conclusion

LipotcGem significantly increased the anti-tumor efficiency and decreased the toxicity for chemotherapy of pancreatic cancer.

"In-silico Design and Development of Novel Hydroxyurea Lipid Drug Conjugates for Breast Cancer Therapy Targeting PI3K/AKT/mTOR Pathway"

Hydroxyurea (HU) has shown promise in breast cancer treatment, but its hydrophilic nature limits its efficacy. Therefore, conjugating HU with lipids could increase its liphophilicity and improve its cellular uptake, leading to increased efficacy and reduced toxicity. The PI3K/Akt/mTOR pathway is an attractive therapeutic target in cancer not only because it is the second most frequently altered pathway after p53, but also because it serves as a convergence point for many stimuli. The aim of this study is to design and develop novel hydroxyurea lipid drug conjugates for breast cancer therapy targeting the PI3K/Akt/mTOR pathway using in-silico and in-vitro approaches. The conjugates are designed and docked with the proteins selected for each target like PI3K (PDB ID;2JDO), AKT (PDB ID;3APF), mTOR (PDB ID;4JST). The conjugates with higher docking scores are taken for ADME studies and molecular dynamics. Stearic, lauric, palmitic, myristic and linolenic acids have been used for the conjugation. The conjugates are synthesized and characterized. The HLB calculation and partition coefficient are carried out to find the improvement in liphophilicity of the conjugates compared to hydroxyurea. Finally, the in-vitro cytotoxicity studies are performed with MCF -7 cell lines and the compound HU-MA (hydroxyurea with myristic acid) with low IC50 is considered as the compound having good activity with compound code. These conjugates have been shown to have improved drug solubility and better cellular uptake compared to free hydroxyurea, which can increase drug efficacy.

Lipid-like gemcitabine diester-loaded liposomes for improved chemotherapy of pancreatic cancer

Gemcitabine (GEM) is a non-selective chemotherapeutic agent used in the treatment of pancreatic cancer. Its antitumor efficacy is limited by a short plasma half-life and severe adverse reactions. To overcome these shortcomings, four novel lipid-like GEM diesters were synthesized and encapsulated into liposomes. Through optimization, dimyristoyl GEM (dmGEM)-loaded liposomes (LipodmGEM) were successfully obtained with an almost complete encapsulation efficiency. Compared to free GEM, LipodmGEM showed enhanced cellular uptake and cell apoptosis, improved inhibition of cell migration on AsPC-1 cells and a greatly extended half-life (7.22 vs. 1.78 h). LipodmGEM succeeded in enriching the drug in the tumor (5.28 vs. 0.03 μmol/g at 8 h), overcoming a major shortcoming of GEM, showed excellent anticancer efficacy in vivo and negligible systemic toxicity, superior to GEM. Attractive as well, suspensions of LipodmGEM remained stable at 2-10 °C away from light for no <2 years. Our results suggest that LipodmGEM might become of high interest for treating pancreatic cancer while the simple strategy we reported might be explored as well for converting other antitumor drugs with high water-solubility and short plasma half-life into attractive nanomedicines.

Biological evaluation of novel gemcitabine analog in patient-derived xenograft models of pancreatic cancer

Gemcitabine (Gem) has been a standard first-line drug for pancreatic cancer (PCa) treatment; however, Gem's rapid metabolism and systemic instability (short half-life) limit its clinical outcome. The objective of this study was to modify Gem into a more stable form called 4-(N)-stearoyl-gemcitabine (4NSG) and evaluate its therapeutic efficacy in patient-derived xenograft (PDX) models from PCa of Black and White patients.Methods 4NSG was synthesized and characterized using nuclear magnetic resonance (NMR), elemental analysis, and high-performance liquid chromatography (HPLC). 4NSG-loaded solid lipid nanoparticles (4NSG-SLN) were developed using the cold homogenization technique and characterized. Patient-derived pancreatic cancer cell lines labeled Black (PPCL-192, PPCL-135) and White (PPCL-46, PPCL-68) were used to assess the in vitro anticancer activity of 4NSG-SLN. Pharmacokinetics (PK) and tumor efficacy studies were conducted using PDX mouse models bearing tumors from Black and White PCa patients.Results 4NSG was significantly stable in liver microsomal solution. The effective mean particle size (hydrodynamic diameter) of 4NSG-SLN was 82 ± 6.7 nm, and the half maximal inhibitory concentration (IC50) values of 4NSG-SLN treated PPCL-192 cells (9 ± 1.1 µM); PPCL-135 (11 ± 1.3 µM); PPCL-46 (12 ± 2.1) and PPCL-68 equaled to 22 ± 2.6 were found to be significantly lower compared to Gem treated PPCL-192 (57 ± 1.5 µM); PPCL-135 (56 ± 1.5 µM); PPCL-46 (56 ± 1.8 µM) and PPCL-68 (57 ± 2.4 µM) cells. The area under the curve (AUC), half-life, and pharmacokinetic clearance parameters for 4NSG-SLN were 3-fourfold higher than that of GemHCl. For in-vivo studies, 4NSG-SLN exhibited a two-fold decrease in tumor growth compared with GemHCl in PDX mice bearing Black and White PCa tumors.Conclusion 4NSG-SLN significantly improved the Gem's pharmacokinetic profile, enhanced Gem's systemic stability increased its antitumor efficacy in PCa PDX mice bearing Black and White patient tumors.

Synthesis, characterization, and anticancer evaluation of 1,3-bistetrahydrofuran-2yl-5-FU as a potential agent for pancreatic cancer

The failure of current chemotherapeutic agents for pancreatic cancer (PCa) makes it the most aggressive soft tissue tumor with a 5-year survival of slightly above 10% and is estimated to be the second leading cause of cancer death by 2030.

OBJECTIVE

The main aim was to synthesize, characterize and evaluate the anticancer activity of 1,3-bistetrahydrofuran-2yl-5FU (MFU).

METHODS

MFU was synthesized by using 5-fluorouracil (5-FU) and tetrahydrofuran acetate, and characterized by nuclear magnetic resonance (NMR), micro-elemental analysis, high-performance liquid chromatography (HPLC), and liquid chromatography with mass spectrophotometry (LC-MS). MFU and Gemcitabine hydrochloride (GemHCl) were tested for antiproliferative activity against MiaPaca-2 and Panc-1 cell lines.

RESULTS

The half-minimum inhibitory concentration (IC50) of MFU was twice lower than that of GemHCl when used in both cell lines. MiaPaca-2 cells (MFU-IC50 = 4.5 ± 1.2 μM vs. GemHCl-IC50 = 10.3 ± 1.1 μM); meanwhile similar trend was observed in Panc-1 cells (MFU-IC50 = 3.0 ± 1 μM vs. GemHCl-IC50 = 6.1 ± 1.03 μM). The MFU and GemHCl effects on 3D spheroids showed a similar trend (IC50-GemHCl = 14.3 ± 1.1 μM vs. IC50-MFU = 7.2 ± 1.1 μM) for MiaPaca-2 cells, and (IC50-GemHCl = 16.3 ± 1.1 μM vs. IC50-MFU = 9.2 ± 1.1 μM) for Panc-1 cells. MFU significantly inhibited clonogenic cell growth, and induced cell death via apoptosis. Cell cycle data showed mean PI for GemHCl (48.5-55.7) twice higher than MFU (24.7 to 27.9) for MiaPaca-2 cells, and similarly to Panc-1 cells. The in-vivo model showed intensely stained EGFR (stained brown) in all control, GemHCl and MFU-treated mice bearing subcutaneous PDX tumors, however, HER2 expression was less stained in MFU-treated tumors compared to GemHCl-treated tumors and controls. Mean tumor volume of MFU-treated mice (361 ± 33.5 mm3) was three-fold lower than GemHCl-treated mice (1074 ± 181.2 mm3) bearing pancreatic PDX tumors.

CONCLUSION

MFU was synthesized with high purity and may have potential anticancer activity against PCa.

Nucleoside transporters and immunosuppressive adenosine signaling in the tumor microenvironment: Potential therapeutic opportunities

Adenosine compartmentalization has a profound impact on immune cell function by regulating adenosine localization and, therefore, extracellular signaling capabilities, which suppresses immune cell function in the tumor microenvironment. Nucleoside transporters, responsible for the translocation and cellular compartmentalization of hydrophilic adenosine, represent an understudied yet crucial component of adenosine disposition in the tumor microenvironment. In this review article, we will summarize what is known regarding nucleoside transporter's function within the purinome in relation to currently devised points of intervention (i.e., ectonucleotidases, adenosine receptors) for cancer immunotherapy, alterations in nucleoside transporter expression reported in cancer, and potential avenues for targeting of nucleoside transporters for the desired modulation of adenosine compartmentalization and action. Further, we put forward that nucleoside transporters are an unexplored therapeutic opportunity, and modulation of nucleoside transport processes could attenuate the pathogenic buildup of immunosuppressive adenosine in solid tumors, particularly those enriched with nucleoside transport proteins.

Antitumor Effects of a Solid Lipid Nanoparticle Loaded with Gemcitabine and Oxaliplatin on the Viability, Apoptosis, Autophagy and Hsp90 of Ovarian Cancer Cells

Aim: The present study aimed to explore the sensitizing capability of the anticancer agents, gemcitabine (GEM) and oxaliplatin (OXA), encapsulated in a novel SLN (GEM:OXA-SLN) against the ovarian cancer cell lines.

METHODS

A novel SLN, prepared using hot homogenization by mixing phosphatidylcholine, cholesterol, tween 80 and oleic acid, was characterized using Transmission Electron Microscope and zetasizer. The anticancer activities and the underlying molecular mechanisms of GEM:OXA-SLN were investigated.

RESULTS

The average z-diameter of the homogeneous spherical GEM:OXA-SLN was (70.33 ± 0.70) nm with zeta potential (-7.69 ± 0.61) mV. GEM:OXA-SLN significantly inhibited the viability of ovarian cancer cells in a dose-dependent manner within 24 h. It also triggered the induction of autophagy cellular death, suppression of multidrug resistance efflux pump and inhibition of heat shock protein (Hsp90).

CONCLUSION

The encapsulation of GEM and OXA in SLN improved the efficacy of the drugs and diminished the ovarian cancer cell's resistance.

Nanoparticle-based therapeutic strategies targeting major clinical challenges in pancreatic cancer treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers due to its aggressiveness and the challenges for early diagnosis and treatment. Recently, nanotechnology has demonstrated relevant strategies to overcome some of the major clinical issues in the treatment of PDAC. This review is focused on the pathological hallmarks of PDAC and the impact of nanotechnology to find solutions. It describes the use of nanoparticle-based systems designed for the delivery of chemotherapeutic agents and combinatorial alternatives that address the chemoresistance associated with PDAC, the development of combination therapies targeting the molecular heterogeneity in PDAC, the investigation of novel therapies dealing with the improvement of immunotherapy and handling the desmoplastic stroma in PDAC by remodeling the tumor microenvironment. A special section is dedicated to the design of nanoparticles for unique non-traditional modalities that could be promising in the future for the improvement in the dismal prognosis of PDAC.

Effect of surface mannosylation on the cytotoxicity and cellular uptake of stearoyl gemcitabine-incorporated, acid-sensitive micelles

Elevated expression of C-type like receptors (CLRs) by tumor cells and tumor-associated macrophages (TAMs) present a unique target for the delivery of anticancer agents. Stearoyl gemcitabine (GemC18)-incorporated, acid-sensitive micelles (G-AS-M) prepared with a stearoyl polyethylene glycol (PEG2000) hydrazone were surface-mannosylated in this study for potential targeted killing of tumor cells and TAMs. The surface mannosylated micelles (i.e. G-MAS-M) were significantly more cytotoxic than the G-AS-M micelles to macrophages and tumor cells that express CLRs. Surprisingly, the uptake of GemC18 in the mannosylated G-MAS-M micelles by the macrophages and tumor cells was lower than that of GemC18 in the G-AS-M micelles. The lack of correlation between the cytoxicity and cellular uptake of GemC18 in the micelles was likely caused by a reduction in the sensitivity of the hydrazone bond linking the PEG2000 to the mannosylated G-MAS-M micelles to hydrolysis, resulting in more stable micelles.

A Tumor-Penetrating Nanomedicine Improves the Chemoimmunotherapy of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant tumors with a low survival rate. The therapeutic effect of chemotherapy and immunotherapy for PDAC is disappointing due to the presence of dense tumor stroma and immunosuppressive cells in the tumor microenvironment (TME). Herein, a tumor-penetrating nanoparticle is reported to modulate the deep microenvironment of PDAC for improved chemoimmunotherapy. The tumor pH-sensitive polymer is synthesized by conjugating N,N-dipentylethyl moieties and monomethoxylpoly(ethylene glycol) onto PAMAM dendrimer, into whose cavity a hydrophobic gemcitabine (Gem) prodrug is accommodated. They self-assemble into nanoparticles (denoted as SPN@Pro-Gem) with the size around 120 nm at neutral pH, but switch into small particles (≈8 nm) at tumor site to facilitate deep delivery of Gem into the tumor parenchyma. In addition to killing cancer cells that resided deeply in the tumor tissue, SPN@Pro-Gem could modulate the TME by reducing the abundance of tumor-associated macrophages and myeloid-derived suppressor cells as well as upregulating the expression level of PD-L1 of tumor cells. This collectively facilitates the infiltration of cytotoxic T cells into the tumors and renders checkpoint inhibitors more effective in previously unresponsive PDAC models. This study reveals a promising strategy for improving the chemoimmunotherapy of pancreatic cancer.

Endocytic Uptake of Solid Lipid Nanoparticles by the Nasal Mucosa

Nanoparticles may provide unique therapeutic opportunities when administered via the nasal cavity, yet the primary uptake and transfer pathways for these particles within the nasal mucosa are not well understood. The endocytic pathways involved in the uptake of fluorescently labeled, (Nile Red) solid lipid nanoparticles (SLNs) of different sizes (~30, 60, and 150 nm) were studied using excised bovine olfactory and nasal respiratory tissues. Endocytic activity contributing to nanoparticle uptake was investigated using a variety of pharmacological inhibitors, but none of the inhibitors were able to completely eliminate the uptake of the SLNs. The continued uptake of nanoparticles following exposure to individual inhibitors suggests that a number of endocytic pathways work in combination to transfer nanoparticles into the nasal mucosa. Following exposure to the general metabolic inhibitors, 2,4-DNP and sodium azide, additional, non-energy-dependent pathways for nanoparticle uptake were also observed. While the smallest nanoparticles (30 nm) were the most resistant to the effects of pharmacologic inhibitors, the largest (150 nm) were still able to transfer significant amounts of the particles into the tissues. The rapid nanoparticle uptake observed demonstrates that these lipid particles are promising vehicles to accomplish both local and systemic drug delivery following nasal administration.

Opportunities and challenges of fatty acid conjugated therapeutics

Instability, poor cellular uptake and unfavorable pharmacokinetics and biodistribution of many therapeutic molecules require modification in their physicochemical properties. The conjugation of these APIs with fatty acids has demonstrated an enhancement in their lipophilicity and stability. The improvement in the formulations that resulted from the conjugation of a drug with a fatty acid includes increased half-life, enhanced cellular uptake and retention, targeted tumor delivery, reduced chemoresistance in cancer, and improved blood-brain-barrier (BBB) penetration. In this review, various therapeutic molecules, including small molecules, peptides and oligonucleotides, that have been conjugated with fatty acid have been thoroughly discussed along with various conjugation strategies. The application of nano-system based delivery is gaining a lot of attention due to its ability to provide controlled drug release, targeting and reducing the extent of side effects. This review also covers various nano-carriers that have been utilized for the delivery of fatty acid drug conjugates. The enhanced lipophilicity of the drug-fatty acid conjugate has shown to enhance the affinity of the drug towards these carriers, thereby increasing the entrapment efficiency and formulation performance.

Enhancing efficacy of gemcitabine in pancreatic patient-derived xenograft mouse models

Gemcitabine (Gem), a nucleoside analog, is a preferred choice of treatment for pancreatic cancer (PCa) and often used in combination therapy against wide range of solid tumors. It is known to be rapidly inactivated in blood by cytidine deaminase. The objective of the study was to improve the systemic stability and anticancer activity of modified Gem termed 4-N-stearoylGem (4NSG) In this study, the IC50 values of 4NSG treated MiaPaCa-2 and primary pancreatic cancer (PPCL-46) cultures were significantly lower when compared with gemcitabine hydrochloride (GemHCl) treated cultures. In acute toxicity study, liver enzyme level of aspartate aminotransferase (AST) of the control mice was not significantly different from AST levels of 4NSG and GemHCl treated mice. However, alanine aminotransferase (ALT) level of control mice (67 ± 5 mUnits/mL) was significantly lower compared with ALT levels of GemHCl (232 ± 28 mUnits/mL) and that of 4NSG (172 ± 22 mUnits/mL) (p < 0.0001). More importantly, ALT level of 4NSG was lower than ALT level of GemHCl (p < 0.05). Although ALT levels were elevated, pathological images of liver and kidney tissues of control, GemHCl and 4NSG treated mice revealed no architectural changes and no significant change in mice weight was observed during treatment. The bioavailability (AUC) of 4NSG was 3-fold high and significantly inhibited the tumor growth as compared with equivalent dose of GemHCl. Immunohistochemical staining revealed that 4NSG significantly inhibited the expression vascular endothelial growth factor (VEGF) receptor. The study is unique because it established, for the first time, enhanced anticancer activity of 4NSG against pancreatic patient-derived xenograft (PDX) mouse model and PPCL-46 cells compared with Gem. 4SGN enhanced pharmacokinetic profile and improved the therapeutic efficacy of the standard-of-care Gem. Lastly, 4GSN showed a remarkable tumor growth inhibition and revealed significant antiangiogenic activity in 4GSN treated pancreatic PDX tumor.

Emerging insights on drug delivery by fatty acid mediated synthesis of lipophilic prodrugs as novel nanomedicines

Many drug molecules that are currently in the market suffer from short half-life, poor absorption, low specificity, rapid degradation, and resistance development. The design and development of lipophilic prodrugs can provide numerous benefits to overcome these challenges. Fatty acids (FAs), which are lipophilic biomolecules constituted of essential components of the living cells, carry out many necessary functions required for the development of efficient prodrugs. Chemical conjugation of FAs to drug molecules may change their pharmacodynamics/pharmacokinetics in vivo and even their toxicity profile. Well-designed FA-based prodrugs can also present other benefits, such as improved oral bioavailability, promoted tumor targeting efficiency, controlled drug release, and enhanced cellular penetration, leading to improved therapeutic efficacy. In this review, we discuss diverse drug molecules conjugated to various unsaturated FAs. Furthermore, various drug-FA conjugates loaded into various nanostructure delivery systems, including liposomes, solid lipid nanoparticles, emulsions, nano-assemblies, micelles, and polymeric nanoparticles, are reviewed. The present review aims to inspire readers to explore new avenues in prodrug design based on the various FAs with or without nanostructured delivery systems.

Biomimetic Gemcitabine-Lipid Prodrug Nanoparticles for Pancreatic Cancer

Gemcitabine (Gem) is a key drug for pancreatic cancer, yet limited by high systemic toxicity, low bioavailability and poor pharmacokinetic profiles. To overcome these limitations, Gem prodrug amphiphiles were synthesised with oleyl, linoleyl and phytanyl chains. Self-assembly and lyotropic mesophase behaviour of these amphiphiles were examined using polarised optical microscopy and Synchrotron SAXS (SSAXS). Gem-phytanyl was found to form liquid crystalline inverse cubic mesophase. This prodrug was combined with phospholipids and cholesterol to create biomimetic Gem-lipid prodrug nanoparticles (Gem-LPNP), verified by SSAXS and cryo-TEM to form liposomes. In vitro testing of the Gem-LPNP in several pancreatic cancer cell lines showed lower toxicity than Gem. However, in a cell line-derived pancreatic cancer mouse model Gem-LPNP displayed greater tumour growth inhibition than Gem using a fraction (<6 %) of the clinical dose and without any systemic toxicity. The easy production, improved efficacy and low toxicity of Gem-LPNP represents a promising new nanomedicine for pancreatic cancer.

Rising horizon in circumventing multidrug resistance in chemotherapy with nanotechnology

Multidrug resistance (MDR) is one of the key barriers in chemotherapy, leading to the generation of insensitive cancer cells towards administered therapy. Genetic and epigenetic alterations of the cells are the consequences of MDR, resulted in drug resistivity, which reflects in impaired delivery of cytotoxic agents to the cancer site. Nanotechnology-based nanocarriers have shown immense shreds of evidence in overcoming these problems, where these promising tools handle desired dosage load of hydrophobic chemotherapeutics to facilitate designing of safe, controlled and effective delivery to specifically at tumor microenvironment. Therefore, encapsulating drugs within the nano-architecture have shown to enhance solubility, bioavailability, drug targeting, where co-administered P-gp inhibitors have additionally combat against developed MDR. Moreover, recent advancement in the stimuli-sensitive delivery of nanocarriers facilitates a tumor-targeted release of the chemotherapeutics to reduce the associated toxicities of chemotherapeutic agents in normal cells. The present article is focused on MDR development strategies in the cancer cell and different nanocarrier-based approaches in circumventing this hurdle to establish an effective therapy against deadliest cancer disease.

Overcoming tumor cell chemoresistance using nanoparticles: lysosomes are beneficial for (stearoyl) gemcitabine-incorporated solid lipid nanoparticles

Despite recent advances in targeted therapies and immunotherapies, chemotherapy using cytotoxic agents remains an indispensable modality in cancer treatment. Recently, there has been a growing emphasis in using nanomedicine in cancer chemotherapy, and several nanomedicines have already been used clinically to treat cancers. There is evidence that formulating small molecular cancer chemotherapeutic agents into nanomedicines significantly modifies their pharmacokinetics and often improves their efficacy. Importantly, cancer cells often develop resistance to chemotherapy, and formulating anticancer drugs into nanomedicines also helps overcome chemoresistance. In this review, we briefly describe the different classes of cancer chemotherapeutic agents, their mechanisms of action and resistance, and evidence of overcoming the resistance using nanomedicines. We then emphasize on gemcitabine and our experience in discovering the unique (stearoyl) gemcitabine solid lipid nanoparticles that are effective against tumor cells resistant to gemcitabine and elucidate the underlying mechanisms. It seems that lysosomes, which are an obstacle in the delivery of many drugs, are actually beneficial for our (stearoyl) gemcitabine solid lipid nanoparticles to overcome tumor cell resistance to gemcitabine.

Development and in-vitro characterization of nanoemulsions loaded with paclitaxel/γ-tocotrienol lipid conjugates

Vitamin E TPGS is a tocopherol (α-T) based nonionic surfactant that was used in the formulation of the Tocosol™ paclitaxel nanoemulsion, which was withdrawn from phase III clinical trials. Unlike tocopherols, however, the tocotrienol (T₃) isomers of vitamin E were found to have innate anticancer activity and were shown to potentiate the antitumor activity of paclitaxel. The primary objective of the present study was therefore to develop a paclitaxel nanoemulsions by substituting α-T oil core of Tocosol™ with γ-T₃ in, and vitamin E TPGS with PEGylated γ-T₃ as the shell, and test the nanoemulsions against Bx-PC-3 and PANC-1 pancreatic tumor cells. A secondary objective was to test the activity of paclitaxel when directly conjugated with the γ-T₃ isomer of vitamin E. The synthesis of the conjugates was confirmed by NMR and mass spectroscopy. Developed nanoemulsions were loaded with free or lipid conjugated paclitaxel. Nanoemulsions droplets were <300 nm with fastest release observed with formulations loaded with free paclitaxel when γ-T₃ was used as the core. Substituting α-T with γ-T₃ was also found to potentiate the anticancer activity of the nanoemulsions. Although marginal increase in activity was observed when nanoemulsions were loaded with free paclitaxel, a significant increase in activity was observed when lipid conjugates were used. The results from this study suggest that the developed paclitaxel nanoemulsions with either γ-T₃, PEGylated γ-T₃, or paclitaxel lipid conjugates may represent a more promising option for paclitaxel delivery in cancer chemotherapy.

Oral 4-(N)-stearoyl gemcitabine nanoparticles inhibit tumor growth in mouse models

In spite of recent advances in targeted tumor therapy, systemic chemotherapy with cytotoxic agents remains a vital cancer treatment modality. Gemcitabine is a nucleoside analog commonly used in the treatment of various solid tumors, but an oral gemcitabine dosage form remain unavailable. Previously, we developed the 4-(N)-stearoyl gemcitabine solid lipid nanoparticles (GemC18-SLNs) by incorporating 4-(N)-stearoyl gemcitabine (GemC18), an amide prodrug of gemcitabine, into solid lipid nanoparticles. GemC18-SLNs, when administered intravenously, showed strong antitumor activity against various human and mouse tumors in mouse models. In the present study, we defined the plasma pharmacokinetics of gemcitabine when GemC18-SLNs were given orally to healthy mice and evaluated the antitumor activity of GemC18-SLNs when given orally in mouse models of lung cancer. In mice orally gavaged with GemC18-SLNs, plasma gemcitabine concentration followed an absorption phase and then clearance phase, with a Tmax of ~2 h. The absolute oral bioavailability of gemcitabine in the GemC18-SLNs was ~70% (based on AUC0-24 h values). In mice with pre-established tumors (i.e. mouse TC-1 or LLC lung cancer cells), oral GemC18-SLNs significantly inhibited the tumor growth and increased mouse survival time, as compared to the molar equivalent dose of gemcitabine hydrochloride or GemC18 in vegetable oil or in Tween 20. Immunohistostaining revealed that oral GemC18-SLNs also have significant antiproliferative, antiangiogenic, and proapoptotic activity in LLC tumors. Formulating a lipophilic amide prodrug of gemcitabine into solid lipid nanoparticles may represent a viable approach toward developing a safe and efficacious gemcitabine oral dosage form.

Lipid-Drug Conjugate for Enhancing Drug Delivery

Lipid-drug conjugates (LDCs) are drug molecules that have been covalently modified with lipids. The conjugation of lipids to drug molecules increases lipophilicity and also changes other properties of drugs. The conjugates demonstrate several advantages including improved oral bioavailability, improved targeting to the lymphatic system, enhanced tumor targeting, and reduced toxicity. Based on the chemical nature of drugs and lipids, various conjugation strategies and chemical linkers can be utilized to synthesize LDCs. Linkers and/or conjugation methods determine how drugs are released from LDCs and are critical for the optimal performance of LDCs. In this review, different lipids used for preparing LDCs and various conjugation strategies are summarized. Although LDCs can be administered without a delivery carrier, most of them are loaded into appropriate delivery systems. The lipid moiety in the conjugates can significantly enhance drug loading into hydrophobic components of delivery carriers and thus generate formulations with high drug loading and superior stability. Different delivery carriers such as emulsions, liposomes, micelles, lipid nanoparticles, and polymer nanoparticles are also discussed in this review.

Synthesis, Characterization, and In Vitro and In Vivo Evaluations of 4-(N)-Docosahexaenoyl 2', 2'-Difluorodeoxycytidine with Potent and Broad-Spectrum Antitumor Activity

In this study, a new compound, 4-(N)-docosahexaenoyl 2′, 2′-difluorodeoxycytidine (DHA-dFdC), was synthesized and characterized. Its antitumor activity was evaluated in cell culture and in mouse models of pancreatic cancer. DHA-dFdC is a poorly soluble, pale yellow waxy solid, with a molecular mass of 573.3 Da and a melting point of about 96°C. The activation energy for the degradation of DHA-dFdC in an aqueous Tween 80–based solution is 12.86 kcal/mol, whereas its stability is significantly higher in the presence of vitamin E. NCI-60 DTP Human Tumor Cell Line Screening revealed that DHA-dFdC has potent and broad-spectrum antitumor activity, especially in leukemia, renal, and central nervous system cancer cell lines. In human and murine pancreatic cancer cell lines, the IC₅₀ value of DHA-dFdC was up to 10⁵-fold lower than that of dFdC. The elimination of DHA-dFdC in mouse plasma appeared to follow a biexponential model, with a terminal phase t_1/2 of about 58 minutes. DHA-dFdC significantly extended the survival of genetically engineered mice that spontaneously develop pancreatic ductal adenocarcinoma. In nude mice with subcutaneously implanted human Panc-1 pancreatic tumors, the antitumor activity of DHA-dFdC was significantly stronger than the molar equivalent of dFdC alone, DHA alone, or the physical mixture of them (1:1, molar ratio). DHA-dFdC also significantly inhibited the growth of Panc-1 tumors orthotopically implanted in the pancreas of nude mice, whereas the molar equivalent dose of dFdC alone did not show any significant activity. DHA-dFdC is a promising compound for the potential treatment of cancers in organs such as the pancreas.

Recent advances in drug delivery strategies for improved therapeutic efficacy of gemcitabine

Gemcitabine (2',2'-difluoro-2'-deoxycytidine; dFdC) is an efficacious anticancer agent acting against a wide range of solid tumors, including pancreatic, non-small cell lung, bladder, breast, ovarian, thyroid and multiple myelomas. However, short plasma half-life due to metabolism by cytidine deaminase necessitates administration of high dose, which limits its medical applicability. Further, due to its hydrophilic nature, it cannot traverse cell membranes by passive diffusion and, therefore, enters via nucleoside transporters that may lead to drug resistance. To circumvent these limitations, macromolecular prodrugs and nanocarrier-based formulations of Gemcitabine are gaining wide recognition. The nanoformulations based approaches by virtue of their controlled release and targeted delivery have proved to improve bioavailability, increase therapeutic efficacy and reduce adverse effects of the drug. Furthermore, the combination of Gemcitabine with other anticancer agents as well as siRNAs using nanocarriers has also been investigated in order to enhance its therapeutic potential. This review deals with challenges and recent advances in the delivery of Gemcitabine with particular emphasis on macromolecular prodrugs and nanomedicines.

How can nanomedicines overcome cellular-based anticancer drug resistance?

This review discusses the mechanisms of anticancer drug resistance according to its cellular level of action and outlines the nanomedicine-based strategies adopted to overcome it.

[Role of RRM1 in the Treatment and Prognosis of Advanced Non-small Cell Lung Cancer]

Lung cancer is one of the most common and highest mortality rates malignant tumors, further, 75%-80% is non-small cell lung cancer (NSCLC). For the majority of patients, lost the chance of radical operation or radiotherapy, chemotherapy is the main treatment. However, because of the diversities of tumor behavior and drug-resistant, the chemotherapy of advanced NSCLC is not optimistic. In recent years, with the application of molecular markers for individual chemotherapy, these patients have achieved prolong life and improved life quality. Individualized chemotherapy based on molecular markers to select the appropriate drug is the problem that needs to be solved. The paper gives a brief review on the role of ribonucleotide reductase subunit 1 (RRM1) in the treatment and prognosis of advanced NSCLC. Individualized chemotherapy by RRM1 can't become commonplace for advanced NSCLC and needs further research.

Solid Lipid Nanoparticles as Efficient Drug and Gene Delivery Systems: Recent Breakthroughs

In recent years, nanomaterials have been widely applied as advanced drug and gene delivery nanosystems. Among them, solid lipid nanoparticles (SLNs) have attracted great attention as colloidal drug delivery systems for incorporating hydrophilic or lipophilic drugs and various macromolecules as well as proteins and nucleic acids. Therefore, SLNs offer great promise for controlled and site specific drug and gene delivery. This article includes general information about SLN structures and properties, production procedures, characterization. In addition, recent progress on development of drug and gene delivery systems using SLNs was reviewed.

Nano graphene oxide: a novel carrier for oral delivery of flavonoids

The interesting physical and chemical properties of graphene oxide (GO) have led to much excitement among biomedical scientists in recent years. It is known that many potent, often aromatic medicines are water insoluble, and this has hindered their administration to treat diseases. Nano GO was synthesized and investigated for its biological application as a carrier for quercetin, a focused bioactive flavonoid widely used as a health supplement and a drug candidate. Different techniques were used to fully evaluate the synthesis, cytotoxicity, and quercetin loading capacity of nano GO. AFM and TEM results confirmed the preparation of planar nanoparticles without aggregation which was verified by reported size results (30 nm) obtained with a particle size analyzer. FTIR and DSC results proved the drug-carrier interaction. In vitro cytotoxicity assays showed that nano GO had no cytotoxicity on A549 cells in different amounts after incubation for 72 h, confirming its suitability as a drug carrier. Our results showed that nano GO can be proposed as a new carrier due to its small size, large specific surface area, low cost, and useful non-covalent interactions with aromatic low-soluble flavonoids such as quercetin. Moreover, it may find widespread applications in biomedicine.

Potential applications of nanotechnology for the diagnosis and treatment of pancreatic cancer

Despite improvements in our understanding of pancreatic cancer and the emerging concept of personalized medicine for the treatment of this disease, it is still the fourth most common cause of cancer death in the western world. It is established that pancreatic cancer is a highly heterogeneous disease with a complex tumor microenvironment. Indeed the extensive stroma surrounding the cancer cells has been shown to be important in promoting tumor growth and metastases, as well as sequestering chemotherapeutic agents consequently decreasing delivery to the tumor cells. Nanotechnology has come to the forefront in the areas of medical diagnostics, imaging, and therapeutic drug delivery. This review will focus on the potential applications of nanotechnology for diagnosis, imaging, and delivery of therapeutic agents for the treatment of pancreatic cancer.

The effect of the acid-sensitivity of 4-(N)-stearoyl gemcitabine-loaded micelles on drug resistance caused by RRM1 overexpression

Chemoresistance is a major issue for most gemcitabine-related chemotherapies. The overexpression of ribonucleotide reductase subunit M1 (RRM1) plays a key role in gemcitabine resistance. In this study, we synthesized a new highly acid-sensitive amphiphilic micelle material by conjugating hydrophilic polyethylene glycol with a hydrophobic stearic acid derivative (C18) using a hydrazone bond, which was named as PHC-2. A lipophilic prodrug of gemcitabine, 4-(N)-stearoyl gemcitabine (GemC18), was loaded into micelles prepared with PHC-2, a previously synthesized less acid-sensitive PHC-1, and their acid-insensitive counterpart, PAC. GemC18 loaded in acid-sensitive micelles can overcome gemcitabine resistance, and GemC18 in the highly acid-sensitive PHC-2 micelles was more cytotoxic than in the less acid-sensitive PHC-1 micelles. Mechanistic studies revealed that upon cellular uptake and lysosomal delivery, GemC18 in the acid-sensitive micelles was released and hydrolyzed more efficiently. Furthermore, GemC18 loaded in the highly acid-sensitive PHC-2 micelles inhibited the expression of RRM1 and increased the level of gemcitabine triphosphate (dFdCTP) in gemcitabine resistant tumor cells. The strategy of delivering lipophilized nucleoside analogs using highly acid-sensitive micelles may represent a new platform technology to increase the antitumor activity of nucleoside analogs and to overcome tumor cell resistance to them.