Study on Biological Characteristics and Mechanism of Paclitaxel Induced Drug Resistance in Endometrial Carcinoma Cells

Recent Progress in Carrier-Free Nanomedicine for Tumor Phototherapy

Safe and effective strategies are urgently needed to fight against the life-threatening diseases of various cancers. However, traditional therapeutic modalities, such as radiotherapy, chemotherapy and surgery, exhibit suboptimal efficacy for malignant tumors owing to the serious side effects, drug resistance and even relapse. Phototherapies, including photodynamic therapy (PDT) and photothermal therapy (PTT), are emerging therapeutic strategies for localized tumor inhibition, which can produce a large amount of reactive oxygen species (ROS) or elevate the temperature to initiate cell death by non-invasive irradiation. In consideration of the poor bioavailability of phototherapy agents (PTAs), lots of drug delivery systems have been developed to enhance the tumor targeted delivery. Nevertheless, the carriers of drug delivery systems inevitably bring biosafety concerns on account of their metabolism, degradation, and accumulation. Of note, carrier-free nanomedicine attracts great attention for clinical translation with synergistic antitumor effect, which is characterized by high drug loading, simplified synthetic method and good biocompatibility. In this review, the latest advances of phototherapy with various carrier-free nanomedicines are summarized, which may provide a new paradigm for the future development of nanomedicine and tumor precision therapy.

Triazole-estradiol analogs: A potential cancer therapeutic targeting ovarian and colorectal cancer

1,2,3-triazoles have continuously shown effectiveness as biologically active systems towards various cancers, and when used in combination with steroid skeletons as a carrier, which can act as a drug delivery system, allows for a creation of a novel set of analogs that may be useful as a pharmacophore leading to a potential treatment option for cancer. A common molecular target for cancer inhibition is that of the Epidermal Growth Factor Receptor/Mitogen Activated Protein Kinase pathways, as inhibition of these proteins is associated with a decrease in cell viability. Estradiol-Triazole analogs were thus designed using a molecular modeling approach. Thirteen of the high scoring analogs were then synthesized and tested in-vitro on an ovarian cancer cell line (A2780) and colorectal cancer cell line (HT-29). The most active compound, Fz25, shows low micromolar activity in both the ovarian (15.29 ± 2.19 µM) and colorectal lines (15.98 ± 0.39 µM). Mechanism of action studies proved that Fz25 moderately arrests cells in the G1 phase of the cell cycle, specifically inhibiting STAT3 in both cell lines. Additionally, Fz57 shows activity in the colorectal line (24.19 ± 1.37 µM). Inhibition studies in both cell lines show inhibition against various proteins in the EGFR pathway, namely EGFR, STAT3, ERK, and mTOR. To further study their effects as therapeutics, Fz25 and Fz57 were studied against drug efflux proteins, which are associated with drug resistance, and were found to inhibit the ABC transporter P-glycoprotein. We can conclude that these estradiol-triazole analogs provide a key for future studies targeting protein inhibition and drug resistance in cancer.

Therapeutic strategies to overcome taxane resistance in cancer

One of the primary causes of attenuated or loss of efficacy of cancer chemotherapy is the emergence of multidrug resistance (MDR). Numerous studies have been published regarding potential approaches to reverse resistance to taxanes, including paclitaxel (PTX) and docetaxel, which represent one of the most important classes of anticancer drugs. Since 1984, following the FDA approval of paclitaxel for the treatment of advanced ovarian carcinoma, taxanes have been extensively used as drugs that target tumor microtubules. Taxanes, have been shown to affect an array of oncogenic signaling pathways and have potent cytotoxic efficacy. However, the clinical success of these drugs has been restricted by the emergence of cancer cell resistance, primarily caused by the overexpression of MDR efflux transporters or by microtubule alterations. In vitro and in vivo studies indicate that the mechanisms underlying the resistance to PTX and docetaxel are primarily due to alterations in α-tubulin and β-tubulin. Moreover, resistance to PTX and docetaxel results from: 1) alterations in microtubule-protein interactions, including microtubule-associated protein 4, stathmin, centriole, cilia, spindle-associated protein, and kinesins; 2) alterations in the expression and activity of multidrug efflux transporters of the ABC superfamily including P-glycoprotein (P-gp/ABCB1); 3) overexpression of anti-apoptotic proteins or inhibition of apoptotic proteins and tumor-suppressor proteins, as well as 4) modulation of signal transduction pathways associated with the activity of several cytokines, chemokines and transcription factors. In this review, we discuss the abovementioned molecular mechanisms and their role in mediating cancer chemoresistance to PTX and docetaxel. We provide a detailed analysis of both in vitro and in vivo experimental data and describe the application of these findings to therapeutic practice. The current review also discusses the efficacy of different pharmacological modulations to achieve reversal of PTX resistance. The therapeutic roles of several novel compounds, as well as herbal formulations, are also discussed. Among them, many structural derivatives had efficacy against the MDR phenotype by either suppressing MDR or increasing the cytotoxic efficacy compared to the parental drugs, or both. Natural products functioning as MDR chemosensitizers offer novel treatment strategies in patients with chemoresistant cancers by attenuating MDR and increasing chemotherapy efficacy. We broadly discuss the roles of inhibitors of P-gp and other efflux pumps, in the reversal of PTX and docetaxel resistance in cancer cells and the significance of using a nanomedicine delivery system in this context. Thus, a better understanding of the molecular mechanisms mediating the reversal of drug resistance, combined with drug efficacy and the application of target-based inhibition or specific drug delivery, could signal a new era in modern medicine that would limit the pathological consequences of MDR in cancer patients.

Herb-Drug Interaction Potential of Licorice Extract and Paclitaxel: A Pharmacokinetic Study in Rats

BACKGROUND AND OBJECTIVES

Licorice is the dried roots and rhizomes of Glycyrrhiza uralensis Fisch (Leguminosae), which is often used with paclitaxel to alleviate paclitaxel-induced pain in clinics. However, the herb-drug interaction between licorice and paclitaxel is still unknown. Our study evaluates the effects of oral licorice on the paclitaxel in rats via pharmacokinetic studies.

METHODS

A simple and rapid ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed to determine paclitaxel in rat. SD rats were randomly divided into 3 groups of 6 animals each as follows: two groups of rats that were pretreated with a daily gavage of licorice (3 g/kg) for 1 or 14 successive days; Control group that was administered distilled water. All rats were then intravenously administered with paclitaxel (3 mg/kg).

RESULTS

The results showed that 14 days pretreatment of licorice could decrease the area under the curve (AUC_0-t) (from 7483.08 ± 528.78 to 6679.12 ± 266.56 mg/L × h) (P < 0.01), and increase the total clearance (CL) (from 0.36 ± 0.02 to 0.39 ± 0.02 L/h/kg) of paclitaxel (P < 0.01). However, a single co-administration of licorice did not significantly alter the pharmacokinetic parameters of paclitaxel, such as AUC_0-t (from 7483.08 ± 528.78 to 7201.24 ± 292.76 mg/L × h) (P > 0.05) and CL (from 0.36 ± 0.02 to 0.36 ± 0.01 L/h/kg) (P > 0.05).

CONCLUSIONS

The results will contribute to better use of licorice in the adjunctive therapy and provide information to study the interaction between herbs and chemotherapy.

Downregulated Mucin 1 alleviates paclitaxel resistance in non‑small cell lung cancer cells

Multidrug resistance of non‑small cell lung cancer (NSCLC) is a common clinical problem, which is one of the main reasons leading to the failure of chemotherapy. Therefore, how to overcome or prevent drug resistance has become a hot and difficult issue in clinical research. The present study was designed to investigate the expression patterns, functions and underlying mechanisms of MUC1 in regulating paclitaxel‑resistant cell line A549/PR in NSCLC. RT‑qPCR and western blot was performed to determine the mRNA and protein level, respectively. CCK‑8 was conducted to determine the cell viability of A549/PR cells. Moreover, flow cytometry assay was applied to examine the apoptosis rate of A549/PR. Herein, the MUC1 was over‑expressed in clinic NSCLC tissues and A549/PR cells. Silence of MUC1 could obviously suppress the proliferation and promote apoptosis of A549/PR cells in treatment of paclitaxel through up‑regulating the expression of Bax and Caspase‑3, and down‑regulating the expression of Bcl‑2, suggesting that chemotherapy combined with the modulation of MUC1 might be characterized as a promising therapeutic approach to overcome paclitaxel‑resistance in NSCLC in the future.

ATG5 knockout promotes paclitaxel sensitivity in drug-resistant cells via induction of necrotic cell death

Autophagy regulators are often effective as potential cancer therapeutic agents. Here, we investigated paclitaxel sensitivity in cells with knockout (KO) of ATG5 gene. The ATG5 KO in multidrug resistant v-Ha-ras-transformed NIH 3T3 cells (Ras-NIH 3T3/Mdr) was generated using the CRISPR/Cas9 technology. The qPCR and LC3 immunoblot confirmed knockout of the gene and protein of ATG5, respectively. The ATG5 KO restored the sensitivity of Ras-NIH 3T3/Mdr cells to paclitaxel. Interestingly, ATG5 overexpression restored autophagy function in ATG5 KO cells, but failed to rescue paclitaxel resistance. These results raise the possibility that low level of resistance to paclitaxel in ATG5 KO cells may be related to other roles of ATG5 independent of its function in autophagy. The ATG5 KO significantly induced a G2/M arrest in cell cycle progression. Additionally, ATG5 KO caused necrosis of a high proportion of cells after paclitaxel treatment. These data suggest that the difference in sensitivity to paclitaxel between ATG5 KO and their parental MDR cells may result from the disparity in the proportions of necrotic cells in both populations. Thus, our results demonstrate that the ATG5 KO in paclitaxel resistant cells leads to a marked G2/M arrest and sensitizes cells to paclitaxel-induced necrosis.

miR-522 facilitates the prosperities of endometrial carcinoma cells by directly binding to monoamine oxidase B

It is well known that microRNAs (miRNAs) are crucial regulatory factors in tumorigenesis, as tumor suppressors or cancer-promoting factors. However, the study of endometrial carcinoma relevance in miR-522 is rare, indicating an undefined molecular mechanism for its role. Therefore, we performed this study to examine the role of miR-522 on the biological behaviors of endometrial carcinoma. In this work, we found that miR-522 was highly expressed in endometrial carcinoma and negatively regulated monoamine oxidase B (MAOB) expression. They also have the opposite effect on prognosis of endometrial carcinoma patients. More importantly, miR-522 could decreased MAOB expression by binding to MAOB with a putative site, thereby promoting cell proliferation, migration, and invasion through in vitro functional analyses, including MTT assay, wound-healing and transwell invasion experiments. Upregulation of MAOB rescued the impacts of miR-522 mimic on cell behaviors. In conclusion, our observations demonstrated that miR-522 accelerated the progression of endometrial carcinoma by inhibiting MAOB, which might lead to a novel therapeutic therapy for endometrial carcinoma.