Paclitaxel and Sorafenib: The Effective Combination of Suppressing the Self-Renewal of Cancer Stem Cells

Recent advances in PAMAM mediated nano-vehicles for targeted drug delivery in Cancer Therapy

3-D multi-faceted, nano-globular PAMAM dendritic skeleton is a highly significant polymer that offers applications in biomedical, industrial, environmental, and agricultural fields. This is mainly due to its enhanced properties, including adjustable surface functionalities, biocompatibility, non-toxicity, high uniformity, and reduced cytotoxicity, as well as its numerous internal cavities. This trait inspires further exploration and advancements in tailoring approaches. The implementation of deliberate strategic modifications in the morphological characteristics of PAMAM is crucial through chemical and biological interventions, in addition to its therapeutic advancements. Thus, the production of peripheral groups remains a prominent and highly advanced technique in molecular fabrication, aimed at boosting the potential of PAMAM conjugates. Currently, there exist numerous dendritic-hybrid materials, despite the widespread use of PAMAM-conjugated frameworks as drug delivery systems, which are well regarded for their efficacy in enhancing potency through the incorporation of surface functions. This paper provides a comprehensive review of recent progress in the design and assembly of various components of PAMAM-conjugates, focusing on their unique formulations. The review encompasses synthetic methodologies, a thorough evaluation of their applicability, and an analysis of their potential functions in the context of Drug Delivery Systems (DDS) in the current period.

Biguanide-anchored albumin-based nanoplatform inhibits epithelial-mesenchymal transition and reduces the stemness phenotype for metastatic cancer therapy

In clinical chemotherapy, albumin-bound paclitaxel (Abraxane) can improve the tumor targeting property and therapeutic efficacy of paclitaxel (PTX) against orthotopic malignancies. However, patients with metastatic cancer have a poor prognosis, probably due to the instability, chemoresistance, and inability of albumin-bound paclitaxel to alter the tumor microenvironment. Here we propose a new biguanide-modified albumin-based nanoplatform that encapsulates paclitaxel for the effective treatment of metastatic cancer. The PTX is encapsulated in poly (lactic-co-glycolic acid) cores coated with biguanide-modified albumin (HSA-NH). The functionalized nanoparticles (HSA-NH NPs) exhibit a remarkable stable profile with low drug release (P < 0.05 versus Abraxane), target tumor tissues, suppress epithelial-mesenchymal transition (EMT) events for anti-metastatic effects, and reduce the phenotype of cancer stem cells. As a result, HSA-NH NPs effectively prolong animal survival (55 days) by inhibiting not only primary tumor growth but also metastasis. This study provides proof of concept that the biguanide-anchored albumin-based nanoplatform encapsulating PTX is a powerful, safe, and clinically translational strategy for the treatment of metastatic cancer. STATEMENT OF SIGNIFICANCE: Albumin-bound paclitaxel (Abraxane) can increase paclitaxel's tumor targeting and therapeutic efficacy in clinical cancer treatments such as breast cancer. However, the instability, chemoresistance, and lack of tumor microenvironment modulation of albumin-bound paclitaxel may lead to poor therapeutic efficacy in metastatic cancer patients. Here we develop biguanide-anchored albumin-based nanoplatforms that encapsulate paclitaxel (HSA-NH NPs) for metastatic cancer treatment. Poly(lactic-co-glycolic acid) (PLGA) cores encapsulating paclitaxel improve the stability of HSA-NH NPs. Based on the activities of metformin, biguanide-anchored albumin adsorbed on PLGA cores improves paclitaxel efficacy, inhibits various aberrant changes during epithelial-mesenchymal transition, and reduces tumor cell stemness. The biguanide-anchored albumin-based nanoplatform encapsulating PTX can serve as a potent, safe, and clinically translational approach for metastatic cancer therapies.

Synergistic Encapsulation of Paclitaxel and Sorafenib by Methoxy Poly(Ethylene Glycol)-b-Poly(Caprolactone) Polymeric Micelles for Ovarian Cancer Therapy

Ovarian cancer has a high mortality rate due to difficult detection at an early stage. It is necessary to develop a novel anticancer treatment that demonstrates improved efficacy while reducing toxicity. Here, using the freeze-drying method, micelles encapsulating paclitaxel (PTX) and sorafenib (SRF) with various polymers were prepared, and the optimal polymer (mPEG-b-PCL) was selected by measuring drug loading (%), encapsulation efficiency (%), particle size, polydispersity index, and zeta potential. The final formulation was selected based on a molar ratio (PTX:SRF = 1:2.3) with synergistic effects on two ovarian cancer cell lines (SKOV3-red-fluc, HeyA8). In the in vitro release assay, PTX/SRF micelles showed a slower release than PTX and SRF single micelles. In pharmacokinetic evaluation, PTX/SRF micelles showed improved bioavailability compared to PTX/SRF solution. In in vivo toxicity assays, no significant differences were observed in body weight between the micellar formulation and the control group. The anticancer effect of PTX/SRF combination therapy was improved compared to the use of a single drug. In the xenografted BALB/c mouse model, the tumor growth inhibition rate of PTX/SRF micelles was 90.44%. Accordingly, PTX/SRF micelles showed improved anticancer effects compared to single-drug therapy in ovarian cancer (SKOV3-red-fluc).

Combination of microtubule targeting agents with other antineoplastics for cancer treatment

Microtubule targeting agents (MTAs) have attracted extensive attention for cancer treatment. However, their clinical efficacies are limited by intolerable toxicities, inadequate efficacy and acquired multidrug resistance. The combination of MTAs with other antineoplastics has become an efficient strategy to lower the toxicities, overcome resistance and improve the efficacies for cancer treatment. In this article, we review the combinations of MTAs with some other anticancer drugs, such as cytotoxic agents, kinases inhibitors, histone deacetylase inhibitors, immune checkpoints inhibitors, to overcome these obstacles. We strongly believe that this review will provide helpful information for combination therapy based on MTAs.

Diphenyleneiodonium efficiently inhibits the characteristics of a cancer stem cell model derived from induced pluripotent stem cells

Diphenyleneiodonium (DPI) has long been evaluated as an anticancer drug inhibiting NADPH oxidase, the IC₅₀ in several cancer cell lines was reported 10 µM, which is too high for efficacy. In this study, we employed miPS-Huh7cmP cells, which we previously established as a cancer stem cell (CSC) model from induced pluripotent stem cells, to reevaluate the efficacy of DPI because CSCs are currently one of the main foci of therapeutic strategy to treat cancer, but generally considered resistant to chemotherapy. As a result, the conventional assay for the cell growth inhibition by DPI accounted for an IC₅₀ at 712 nM that was not enough to define the effectiveness as an anticancer drug. Simultaneously, the wound-healing assay revealed an IC₅₀ of approximately 500 nM. Comparatively, the IC₅₀ values shown on sphere formation, colony formation, and tube formation assays were 5.52, 12, and 8.7 nM, respectively. However, these inhibitory effects were not observed by VAS2780, also a reputed NADPH oxidase inhibitor. It is noteworthy that these three assays are evaluating the characteristic of CSCs and are designed in the three-dimensional (3D) culture methods. We concluded that DPI could be a suitable candidate to target mitochondrial respiration in CSCs. We propose that the 3D culture assays are more efficient to screen anti-CSC drug candidates and better mimic tumor microenvironment when compared to the adherent monolayer of 2D culture system used for a conventional assay, such as cell growth inhibition and wound-healing assays.

The significance of ErbB2/3 in the conversion of induced pluripotent stem cells into cancer stem cells

Cancer stem cells (CSCs) are suggested to be responsible for drug resistance and aggressive phenotypes of tumors. Mechanisms of CSC induction are still under investigation. Our lab has established a novel method to generate CSCs from iPSCs under a cancerous microenvironment mimicked by the conditioned medium (CM) of cancer-derived cells. Here, we analyzed the transcriptome of CSCs, which were converted from iPSCs with CM from pancreatic ductal adenocarcinoma cells. The differentially expressed genes were identified and used to explore pathway enrichment. From the comparison of the CSCs with iPSCs, genes with elevated expression were related to the ErbB2/3 signaling pathway. Inhibition of either ErbB2 with lapatinib as a tyrosine kinase inhibitor or ErbB3 with TX1-85-1 or siRNAs arrested cell proliferation, inhibited the in vitro tumorigenicity, and lead to loss of stemness in the converting cells. The self-renewal and tube formation abilities of cells were also abolished while CD24 and Oct3/4 levels were reduced, and the MAPK pathway was overactivated. This study shows a potential involvement of the ErbB2/ErbB3 pathway in CSC generation and could lead to new insight into the mechanism of tumorigenesis and the way of cancer prevention.

Porphyrin Based 2D-MOF Structures as Dual-Kinetic Sorafenib Nanocarriers for Hepatoma Treatment

The existing clinical protocols of hepatoma treatment require improvement of drug efficacy that can be achieved by harnessing nanomedicine. Porphyrin-based, paddle-wheel framework (PPF) structures were obtained and tested as dual-kinetic Sorafenib (SOR) nanocarriers against hepatoma. We experimentally proved that sloughing of PPF structures combined with gradual dissolving are effective mechanisms for releasing the drug from the nanocarrier. By controlling the PPF degradation and size of adsorbed SOR deposits, we were able to augment SOR anticancer effects, both in vitro and in vivo, due to the dual kinetic behavior of SOR@PPF. Obtained drug delivery systems with slow and fast release of SOR influenced effectively, although in a different way, the cancer cells proliferation (reflected with EC50 and ERK 1/2 phosphorylation level). The in vivo studies proved that fast-released SOR@PPF reduces the tumor size considerably, while the slow-released SOR@PPF much better prevents from lymph nodes involvement and distant metastases.

Oxidative Stress Activated by Sorafenib Alters the Temozolomide Sensitivity of Human Glioma Cells Through Autophagy and JAK2/STAT3-AIF Axis

The development of temozolomide (TMZ) resistance in glioma leads to poor patient prognosis. Sorafenib, a novel diaryl urea compound and multikinase inhibitor, has the ability to effectively cross the blood-brain barrier. However, the effect of sorafenib on glioma cells and the molecular mechanism underlying the ability of sorafenib to enhance the antitumor effects of TMZ remain elusive. Here, we found that sorafenib could enhance the cytotoxic effects of TMZ in glioma cells in vitro and in vivo. Mechanistically, the combination of sorafenib and TMZ induced mitochondrial depolarization and apoptosis inducing factor (AIF) translocation from mitochondria to nuclei, and this process was dependent on STAT3 inhibition. Moreover, the combination of sorafenib and TMZ inhibited JAK2/STAT3 phosphorylation and STAT3 translocation to mitochondria. Inhibition of STAT3 activation promoted the autophagy-associated apoptosis induced by the combination of sorafenib and TMZ. Furthermore, the combined sorafenib and TMZ treatment induced oxidative stress while reactive oxygen species (ROS) clearance reversed the treatment-induced inhibition of JAK2/STAT3. The results indicate that sorafenib enhanced the temozolomide sensitivity of human glioma cells by inducing oxidative stress-mediated autophagy and JAK2/STAT3-AIF axis.

Paclitaxel-Based Chemotherapy Targeting Cancer Stem Cells from Mono- to Combination Therapy

Paclitaxel (PTX) is a chemotherapeutical agent commonly used to treat several kinds of cancer. PTX is known as a microtubule-targeting agent with a primary molecular mechanism that disrupts the dynamics of microtubules and induces mitotic arrest and cell death. Simultaneously, other mechanisms have been evaluated in many studies. Since the anticancer activity of PTX was discovered, it has been used to treat many cancer patients and has become one of the most extensively used anticancer drugs. Regrettably, the resistance of cancer to PTX is considered an extensive obstacle in clinical applications and is one of the major causes of death correlated with treatment failure. Therefore, the combination of PTX with other drugs could lead to efficient therapeutic strategies. Here, we summarize the mechanisms of PTX, and the current studies focusing on PTX and review promising combinations.

Current Perspectives on Taxanes: Focus on Their Bioactivity, Delivery and Combination Therapy

Taxanes, mainly paclitaxel and docetaxel, the microtubule stabilizers, have been well known for being the first-line therapy for breast cancer for more than the last thirty years. Moreover, they have been also used for the treatment of ovarian, hormone-refractory prostate, head and neck, and non-small cell lung carcinomas. Even though paclitaxel and docetaxel significantly enhance the overall survival rate of cancer patients, there are some limitations of their use, such as very poor water solubility and the occurrence of severe side effects. However, this is what pushes the research on these microtubule-stabilizing agents further and yields novel taxane derivatives with significantly improved properties. Therefore, this review article brings recent advances reported in taxane research mainly in the last two years. We focused especially on recent methods of taxane isolation, their mechanism of action, development of their novel derivatives, formulations, and improved tumor-targeted drug delivery. Since cancer cell chemoresistance can be an unsurpassable hurdle in taxane administration, a significant part of this review article has been also devoted to combination therapy of taxanes in cancer treatment. Last but not least, we summarize ongoing clinical trials on these compounds and bring a perspective of advancements in this field.

An assay for cancer stem cell-induced angiogenesis on chick chorioallantoic membrane

Angiogenesis is generally involved in tumor growth and metastasis. Cancer stem cells (CSCs) are considered to facilitate the angiogenesis. Therefore, CSCs could be the effective targets to stop angiogenesis. Recently, our group successfully generated CSC models from induced pluripotent stem cells (iPSCs) in the presence of conditioned medium derived from cancer derived cells. These novel model CSCs has been characterized by highly tumorigenic, angiogenic and metastatic potentials in vivo. The angiogenic potential of CSCs has been explained by the expression of both angiogenic factors and their receptors implying the angiogenesis in autocrine manner. In this protocol we optimized the method to evaluate tumor angiogenesis with the CSC model, which was described effective to assess sorafenib as an antiangiogenic drug, on chick chorioallantoic membrane (CAM) assay. Our results demonstrate that CSCs developed from iPSCs and CAM assay are a robust and cost-effective tool to evaluate tumor angiogenesis with CSCs. Collectively, CSCs in CAM assay could serve as a very useful model for the screening of potential therapeutic agents targeting tumor angiogenesis.