Synthetic paclitaxel-octreotide conjugate reverses the resistance of paclitaxel in A2780/Taxol ovarian cancer cell line

Glucose-6-phosphate dehydrogenase: a therapeutic target for ovarian cancer

INTRODUCTION

Ovarian cancer (OC) is a gynecological tumor disease, which is usually diagnosed at an advanced stage and has a poor prognosis. It has been established that the glucose metabolism rate of cancer cells is significantly higher than that of normal cells, and the pentose phosphate pathway (PPP) is an important branch pathway for glucose metabolism. Glucose-6-phosphate dehydrogenase (G6PD) is the key rate-limiting enzyme in the PPP, which plays an important role in the initiation and development of cancer (such as OC), and has been considered as a promisinganti-cancer target.

AREAS COVERED

In this review, based on the structure and biological function of G6PD, recent research on the roles of G6PD in the progression, metastasis, and chemoresistance of OC are summarized and accompanied by proposed molecular mechanisms, which may provide a systematic understanding of targeting G6PD for the treatment of patients with OC.

EXPERT OPINION

Accumulating evidence demonstrates that G6PD is a promising target of cancer. The development of G6PD inhibitors for cancer treatment merits broad application prospects.

Octreotide and Octreotide-derived delivery systems

Pharmaceutical peptide Octreotide is a somatostatin analog with targeting and therapeutic abilities. Over the last decades, Octreotide has been developed and approved to treat acromegaly and neuroendocrine tumours, and Octreotide-based radioactive conjugates have been leveraged clinically to detect small neuroendocrine tumour sites. Meanwhile, variety of Octreotide-derived delivery strategies have been proposed and explored for tumour targeted therapeutics or diagnostics in preclinical or clinical settings. In this review, we especially focus on the preclinical development and applications of Octreotide-derived drug delivery systems, diagnostic nanosystems, therapeutic nanosystems and multifunctional nanosystems, we also briefly discuss challenges and prospects of these Octreotide-derived delivery systems.

Selective delivery of clinically approved tubulin binding agents through covalent conjugation to an active targeting moiety

Abstract:

The efficacy and tolerability of tubulin binding agents are hampered by their low specificity for cancer cells, like most clinically used anticancer agents. To improve specificity, tubulin binding agents have been covalently conjugated to agents which target cancer cells to give actively targeted drug conjugates. These conjugates are designed to increase uptake of the drug by cancer cells, while having limited uptake by normal cells thereby improving efficacy and tolerability. Approaches used include attachment to small molecules, polysaccharides, peptides, proteins and antibodies that exploit the overexpression of receptors for these substances. Antibody targeted strategies have been the most successful to date with six such examples having gained clinical approval. Many other conjugate types, especially those targeting the folate receptor, have shown promising efficacy and toxicity profiles in pre-clinical models and in early-stage clinical studies. Presented herein is a discussion of the success or otherwise of the recent strategies used to form these actively targeted conjugates.

The development of peptide-drug conjugates (PDCs) strategies for paclitaxel

INTRODUCTION

Paclitaxel is a powerful and effective anti-tumor drug with wide clinical application. However, there are still some limitations, including poor water solubility, low specificity, and susceptibility to drug resistance. The peptide-drug conjugates (PDCs) represent a rising class of therapeutic drugs, which combines small-molecule chemotherapeutic drugs with highly flexible peptides through a cleavable or non-cleavable linker. When this strategy is applied, the therapeutic effects of paclitaxel can be improved.

AREAS COVERED

In this review, we discuss the application of the PDCs strategy in paclitaxel, including two parts: the tumor targeting peptide-paclitaxel conjugates and the cell penetrating peptide-paclitaxel conjugates.

EXPERT OPINION

Combining drugs with multifunctional peptides covalently is an effective strategy for delivering paclitaxel to tumors. Depending on different functional peptides, conjugates can increase the water solubility of paclitaxel, tumor permeability of paclitaxel, the accumulation of paclitaxel in tumor tissues, and enhance the antitumor effect of paclitaxel. In addition, due to the change of cell entry mechanism, partial conjugates can restore the therapeutic activity of paclitaxel against resistant tumors. Notably, in order to better translate into the clinical field in the future, more research should be conducted to ensure the safety and effectiveness of peptide-paclitaxel conjugates.

A Compressive Review about Taxol®: History and Future Challenges

Taxol^®, which is also known as paclitaxel, is a chemotherapeutic agent widely used to treat different cancers. Since the discovery of its antitumoral activity, Taxol^® has been used to treat over one million patients, making it one of the most widely employed antitumoral drugs. Taxol^® was the first microtubule targeting agent described in the literature, with its main mechanism of action consisting of the disruption of microtubule dynamics, thus inducing mitotic arrest and cell death. However, secondary mechanisms for achieving apoptosis have also been demonstrated. Despite its wide use, Taxol^® has certain disadvantages. The main challenges facing Taxol^® are the need to find an environmentally sustainable production method based on the use of microorganisms, increase its bioavailability without exerting adverse effects on the health of patients and minimize the resistance presented by a high percentage of cells treated with paclitaxel. This review details, in a succinct manner, the main aspects of this important drug, from its discovery to the present day. We highlight the main challenges that must be faced in the coming years, in order to increase the effectiveness of Taxol^® as an anticancer agent.

Octreotide-Paclitaxel Conjugate Reverses Paclitaxel Resistance by p38 Mitogen-Activated Protein Kinase (MAPK) Signaling Pathway in A2780/Taxol Human Ovarian Cancer Cells

Background

Platinum plus paclitaxel is a first-line chemotherapy for ovarian cancer. Platinum resistance is a hot topic for many scholars, but drug resistance caused by paclitaxel is also a topic of concern. Currently, scholars believe that inhibition of MAPK signaling pathway may be an effective way to reverse the drug resistance of tumor paclitaxel.

Material/Methods

A2780/Taxol cells or nude mice were divided into 8 groups: control group, OCT (octreotide) group, OC (octreotide+cyclosomatostatin) group, PTX (paclitaxel) group, PO (paclitaxel+octreotide) group, POC (paclitaxel+octreotide+cyclosomatostatin) group, P-O (octreotide-paclitaxel conjugate) group, and P-OC (octreotide-paclitaxel conjugate+cyclosomatostatin) group. The phosphorylation level of p38 MAPK and the expression level of vascular endothelial growth factor (VEGF) were determined by western blot. Flow cytometry was used to discover the apoptosis of A2780/Taxol cells and xenografts. The expression of class III beta-tubulin was detected by immunohistochemistry.

Results

Octreotide-paclitaxel conjugate inhibited phosphorylation of the p38MAPK signal pathway, decreased the expression of downstream VEGF, and increased the apoptosis of drug-resistant cancer cells. In addition, it reduced the expression of class III beta-tubulin protein and increase the sensitivity of drug-resistant cells to paclitaxel. All these effects of octreotide-paclitaxel conjugate were cancelled by cyclosomatostatin.

Conclusions

Octreotide-paclitaxel conjugate can reverse the paclitaxel resistance of A2780/Taxol human ovarian cancer cells by inhibiting the activity of p38 MAPK signaling pathway.

Treatment with β-elemene combined with paclitaxel inhibits growth, migration, and invasion and induces apoptosis of ovarian cancer cells by activation of STAT-NF-κB pathway

In this study, we aimed to analyze the anti-cancer effects of β-elemene combined with paclitaxel for ovarian cancer. RT-qPCR, MTT assay, western blot, flow cytometry, and immunohistochemistry were used to analyze in vitro and in vivo anti-cancer effects of combined treatment of β-elemene and paclitaxel. The in vitro results showed that β-elemene+paclitaxel treatment markedly inhibited ovarian cancer cell growth, migration, and invasion compared to either paclitaxel or β-elemene treatment alone. Results demonstrated that β-elemene+paclitaxel induced apoptosis of SKOV3 cells, down-regulated anti-apoptotic Bcl-2 and Bcl-xl gene expression and up-regulated pro-apoptotic P53 and Apaf1 gene expression in SKOV3 cells. Administration of β-elemene+paclitaxel arrested SKOV3 cell cycle at S phase and down-regulated CDK1, cyclin-B1, and P27 gene expression and apoptotic-related resistant gene expression of MDR1, LRP, and TS in SKOV3 cells. In vivo experiments showed that treatment with β-elemene+paclitaxel significantly inhibited ovarian tumor growth and prolonged the overall survival of SKOV3-bearing mice. In addition, the treatment inhibited phosphorylated STAT3 and NF-κB expression in vitro and in vivo. Furthermore, it inhibited migration and invasion through down-regulation of the STAT-NF-κB signaling pathway in SKOV3 cells. In conclusion, the data suggested that β-elemene+paclitaxel can inhibit ovarian cancer growth via down-regulation of the STAT3-NF-κB signaling pathway, which may be a potential therapeutic strategy for ovarian cancer therapy.

Identification and imaging of miR-155 in the early screening of lung cancer by targeted delivery of octreotide-conjugated chitosan-molecular beacon nanoparticles

Lung cancer is still the most common cancer globally. Early screening remains the key to improve the prognosis of patients. There is currently a lack of specific and sensitive methods for early screening of lung cancer. In recent years, studies have found that microRNA plays an important role in the occurrence and development of lung cancer and become a biological target in the early diagnosis of lung cancer. In this study, lung cancer cells, subcutaneous xenografts of lung cancer in nude mice, and Lox-Stop-lox K-ras G12D transgenic mice were used as models. The transgenic mice displayed the dynamic processes from normal lung tissue to atypical hyperplasia, adenomas, carcinoma in situ and lung adenocarcinoma. It was found that miR-155 and somatostatin receptor 2 (SSTR2) were expressed in all the disease stages of transgenic mice. Through molecular beacon (MB) technology and nanotechnology, chitosan-molecular beacon (CS-MB) nanoparticles and targeted octreotide (OCT) were conjugated and synthesized. The octreotide-conjugated chitosan-molecular beacon nanoparticles (CS-MB-OCT) can specifically bind to SSTR2 expressed by the lung cancer cells to achieve the goal of identification of lung cancer cells and imaging miR-155 in vivo and in vitro. Fluorescence imaging at different disease stages of lung cancer in Lox-Stop-lox K-ras G12D transgenic mice was performed, and could dynamically monitor the occurrence and development of lung cancer by different fluorescence intensity ranges. The current research, in turn, provides new idea, new method, and new technology for the early screening of lung cancer.