Imaging of multidrug resistance in cancer

Polyphenols Modulating Effects of PD-L1/PD-1 Checkpoint and EMT-Mediated PD-L1 Overexpression in Breast Cancer

Investigating dietary polyphenolic compounds as antitumor agents are rising due to the growing evidence of the close association between immunity and cancer. Cancer cells elude immune surveillance for enhancing their progression and metastasis utilizing various mechanisms. These mechanisms include the upregulation of programmed death-ligand 1 (PD-L1) expression and Epithelial-to-Mesenchymal Transition (EMT) cell phenotype activation. In addition to its role in stimulating normal embryonic development, EMT has been identified as a critical driver in various aspects of cancer pathology, including carcinogenesis, metastasis, and drug resistance. Furthermore, EMT conversion to another phenotype, Mesenchymal-to-Epithelial Transition (MET), is crucial in developing cancer metastasis. A central mechanism in the upregulation of PD-L1 expression in various cancer types is EMT signaling activation. In breast cancer (BC) cells, the upregulated level of PD-L1 has become a critical target in cancer therapy. Various signal transduction pathways are involved in EMT-mediated PD-L1 checkpoint overexpression. Three main groups are considered potential targets in EMT development; the effectors (E-cadherin and Vimentin), the regulators (Zeb, Twist, and Snail), and the inducers that include members of the transforming growth factor-beta (TGF-β). Meanwhile, the correlation between consuming flavonoid-rich food and the lower risk of cancers has been demonstrated. In BC, polyphenols were found to downregulate PD-L1 expression. This review highlights the effects of polyphenols on the EMT process by inhibiting mesenchymal proteins and upregulating the epithelial phenotype. This multifunctional mechanism could hold promises in the prevention and treating breast cancer.

Fluorine-18-Labeled Fluorescent Dyes for Dual-Mode Molecular Imaging

Recent progress realized in the development of optical imaging (OPI) probes and devices has made this technique more and more affordable for imaging studies and fluorescence-guided surgery procedures. However, this imaging modality still suffers from a low depth of penetration, thus limiting its use to shallow tissues or endoscopy-based procedures. In contrast, positron emission tomography (PET) presents a high depth of penetration and the resulting signal is less attenuated, allowing for imaging in-depth tissues. Thus, association of these imaging techniques has the potential to push back the limits of each single modality. Recently, several research groups have been involved in the development of radiolabeled fluorophores with the aim of affording dual-mode PET/OPI probes used in preclinical imaging studies of diverse pathological conditions such as cancer, Alzheimer's disease, or cardiovascular diseases. Among all the available PET-active radionuclides, 18F stands out as the most widely used for clinical imaging thanks to its advantageous characteristics (t1/2 = 109.77 min; 97% β+ emitter). This review focuses on the recent efforts in the synthesis and radiofluorination of fluorescent scaffolds such as 4,4-difluoro-4-bora-diazaindacenes (BODIPYs), cyanines, and xanthene derivatives and their use in preclinical imaging studies using both PET and OPI technologies.

Expression profile of stem cell markers and ABC transporters in 5-fluorouracil resistant Hep-2 cells

Resistance of laryngeal squamous cell carcinoma cells to traditional therapeutic regimens still remains to be a major reason for therapeutic failure in patients. In this study, we aimed at investigating the expression profiles of ATP-binding cassette (ABC) transporters and stem cell markers in 5-fluorouracil (5-FU) resistant laryngeal Hep-2 cells. We treated parental Hep-2 cells, with stepwise increased doses of 5-FU for almost 1 year to develop 5-FU resistant sub-lines with resistance against varying levels of 5-FU concentrations (4 sub-lines resistant to 1, 2, 4, and eightfold of 5-FU). Then, we measured the expression levels of 10 genes from ABC transporters family and 4 stem cell associated markers using quantitative reverse transcription polymerase chain reaction (qRT-PCR) to find out a potential relationship between these markers and chemoresistance. We found that stemness-associated markers had elevated expressions from the beginning of 5-FU resistance acquisition. Their expressions elevated stepwise while parental Hep-2 cells got resistance to higher doses of 5-FU. Expressions of tested ABC transporters (ABCA5, ABCB1, ABCB6, ABCC1, ABCC2, ABCC3, ABCC5, ABCC10 and ABCF2, and ABCG2) were also deregulated in 5-FU resistant Hep-2 cells. Although their expressions remained unaltered at the beginning of acquisition of resistance, expressions of ABC transporters except from ABCB6 increased significantly when cells became resistant to higher doses of 5-FU. Our results suggest that enrichment of cells with stemness characteristics and upregulation of ABC transporters might be amongst the crucial contributors of chemoresistance in laryngeal cancer cells.

Inflammatory pathway interactions and cancer multidrug resistance regulation

Multidrug resistances against chemotherapeutics are among the major challenges related to cancer treatment. Recent studies have demonstrated that different conditions may tune the expression and activity of MDR transporters. For instance, inflammation occurs through a complex cytological process and chemical reactions in the most tumor microenvironment; it can play a critical role in cancer development and is capable of altering the expression and function of MDR transporters. Cytokines, interleukins, and prostaglandins are potent inflammatory mediators that can modulate the expression of MDRs at transcriptional and post-transcriptional levels in the most human cancer cells and tissues and potentially contribute to balance bioavailability of chemotherapeutic agents. Since cancer cases are usually accompanied by inflammatory responses, glucocorticoids and NSAIDs are the primary useful combination chemotherapies in a variety of cancer treatment protocols. In addition to the anti-inflammatory activities of these agents, they exert diverse modulatory effects on MDR-mediated drug resistance via specific mechanisms. Several factors, including cell and MDR-protein types, pharmacokinetics, and pharmacogenetics, mainly influence the regulatory mechanisms. Uncovering the networks between inflammation and multidrug resistance will be clinically helpful in the treatment of malignant cancers and decreasing the cancer mortality rates.

Lung clearance of inhaled aerosol of Tc-99m-methoxyisobutyl isonitrile: relationships with cigarette smoking, age and gender

Tc-99m-methoxyisobutyl isonitrile (Tc-99m-MIBI) is a radiolabelled xenobiotic, the disappearance rate of which from lungs following inhalation as a radioaerosol correlates inversely with bronchopulmonary multidrug resistance protein 1 (MRP1) expression. Tc-99m-MIBI clearance has previously been shown to be delayed in cigarette smokers. The aim of the current study was to determine whether smoking correlates with bronchopulmonary MRP1 expression, to confirm that Tc-99m-MIBI disappearance rate from the lungs following inhalation is delayed in smokers, and to determine the effects of gender and age on disappearance rate. Participants underwent dynamic imaging for 40 min over the lungs following inhalation of Tc-99m-MIBI using a double-headed gamma camera. The half-time of clearance was obtained from geometric mean of anterior and posterior counts and averaged between the two lungs. Paraffin-embedded tissue obtained from healthy lung during surgery in 13 patients was graded immunohistochemically for MRP1 as negative (0), weak (1), moderate (2) or strong (3). In 4 non-smokers, grading was 1 in three and 0 in one. In 9 smokers, in contrast, expression was graded 2-3 in 8 and 1 in one (P<0·02). Mean clearance half-time in smokers (142 ± 29 min; n = 17) was longer than in non-smokers (91 ± 14 min; n = 18; P<0·0001). In non-smokers, half-times were not significantly different between men (96 ± 16; n = 6) min and women (88 ± 12 min; P = 0·2). Combining genders into one group, half-time correlated with participant age (P = 0·0005). We conclude that smoking upregulates MRP1 and delays clearance of inhaled Tc-99m-MIBI. There is no significant gender difference in non-smokers but ageing is associated with longer clearance half-times.

Influence of 3-{5-[4-(diethylamino)benzylidene]rhodanine}propionic acid on the conformation of 5-(4-chlorobenzylidene)-2-(4-methylpiperazin-1-yl)-3H-imidazol-4(5H)-one

The arylidene-imidazolone derivatives are a group of compounds of great interest in medicinal chemistry due to their various pharmacological actions. In order to study the possible conformations of an arylidene-imidazolone derivative, two new crystal structures were determined by X-ray diffraction, namely (Z)-5-(4-chlorobenzylidene)-2-(4-methylpiperazin-1-yl)-3H-imidazol-5(4H)-one, C₁₅H₁₇ClN₄O, (6), and its salt 4-[5-(4-chlorobenzylidene)-5-oxo-4,5-dihydro-3H-imidazol-2-yl]-1-methylpiperazin-1-ium 3-{5-[4-(diethylamino)benzylidene]-4-oxo-2-thioxothiazolidin-3-yl}propionate, C₁₅H₁₈ClN₄O⁺·C₁₇H₁₉N₂O₃S₂^-, (7). Both compounds crystallize in the space group P-1. The basic form (6) crystallizes with two molecules in the asymmetric unit. In the acid form of (6), the N atom of the piperazine ring is protonated by proton transfer from the carboxyl group of the rhodanine acid derivative. The greatest difference in the conformations of (6) and its protonated form, (6c), is observed in the location of the arylidene-imidazolone substituent at the N atom. In the case of (6c), the position of this substituent is close to axial, while for (6), the corresponding position is intermediate between equatorial and axial. The crystal packing is dominated by a network of N-H...O hydrogen bonds. Furthermore, the crystal structures are stabilized by numerous intermolecular contacts of types C-H...N and C-H...Cl in (6), and C-H...O and C-H...S in (7). The geometry with respect to the location of the substituents at the N atoms of the piperazine ring was compared with other crystal structures possessing an N-methylpiperazine moiety.

Tumor uptake and tumor/blood ratios for [89Zr]Zr-DFO-trastuzumab-DM1 on microPET/CT images in NOD/SCID mice with human breast cancer xenografts are directly correlated with HER2 expression and response to trastuzumab-DM1

INTRODUCTION

Our objective was to determine correlations between the tumor uptake and T/B ratios for ⁸⁹Zr-labeled T-DM1 (⁸⁹Zr-DFO-T-DM1) in mice with human BC xenografts by microPET/CT and biodistribution studies with HER2 expression and response to treatment with trastuzumab-DM1 (T-DM1).

METHODS

The tumor and normal tissue uptake and T/B ratios for ⁸⁹Zr-DFO-T-DM1 (10 μg; 7.0 MBq) incorporated into a therapeutic dose (60 μg) were determined by microPET/CT and biodistribution studies at 96 h p.i. in NOD/SCID mice with s.c. MDA-MB-231 (5 × 10⁴ HER2/cell), MDA-MB-361 (5 × 10⁵ HER2/cell) and BT-474 (2 × 10⁶ HER2/cell) human BC xenografts. Mice bearing these tumors were treated with T-DM1 (3.6 mg/kg every 3 weeks) and the tumor doubling time estimated by fitting of tumor volume vs. time curves. A tumor doubling time ratio (TDR) was calculated by dividing the doubling time for T-DM1 and normal saline treated control mice. The clonogenic survival (CS) of BC cells with increasing HER2 expression treated for 72 h in vitro with T-DM1 or trastuzumab (0-100 μg/mL) was compared. Correlations were determined between the T/B ratios for ⁸⁹Zr-DFO-T-DM1 and HER2 expression, TDR and CS, and between CS and TDR.

RESULTS

Uptake of ⁸⁹Zr-DFO-T-DM1 in MDA-MB-231, MDA-MB-361 and BT-474 tumors was 2.4 ± 0.4%ID/g, 6.9 ± 2.2%ID/g and 9.8 ± 1.1%ID/g, respectively. There was a non-linear but direct correlation between the T/B ratios for ⁸⁹Zr-DFO-T-DM1 and HER2 expression with the T/B ratio ranging from 4.5 ± 0.7 for MDA-MB-231 to 18.2 ± 1.8 for MDA-MB-361 and 35.9 ± 5.1 for BT-474 xenografts. Tumor intensity on microPET/CT images was proportional to HER2 expression. The standard uptake value (SUV) for the tumors on the images was strongly correlated with the T/B ratio in biodistribution studies. There was a direct linear correlation between the T/B ratio for ⁸⁹Zr-DFO-T-DM1 and TDR, with TDR ranging from 0.9 for MDA-MB-231 to 1.6 for MDA-MB-361 and 2.1 for BT-474 tumors. The cytotoxicity of T-DM1 in vitro on BC cells was dependent on HER2 expression but T-DM1 was more potent than trastuzumab. There was an inverse correlation between the TDR for mice treated with T-DM1 and CS of BC cells exposed in vitro to T-DM1.

CONCLUSIONS

Based on the direct correlations between the T/B ratio for ⁸⁹Zr-DFO-T-DM1 by PET and HER2 expression and response to T-DM1, our results suggest that PET with ⁸⁹Zr-DFO-T-DM1 may predict response of HER2-positive BC to treatment with T-DM1.

ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE

Our results suggest that PET with ⁸⁹Zr-DFO-T-DM1 may predict response to treatment with T-DM1 in HER-positive BC.

99mTc-sestamibi SPECT/CT for the characterization of renal masses: a pictorial guide

In parallel to the increased utilization of cross-sectional imaging, the incidence of small renal masses has steadily risen in recent years. At the present time, anatomical imaging techniques are limited in their ability to differentiate benign from malignant renal masses. Moreover, renal mass biopsy has a high non-diagnostic rate, poor negative-predictive ability, and carries potential risks as well as substantial costs. As a result, benign renal masses are often unnecessarily resected for the false presumption of cancer. ^99mTc-sestamibi single photon emission computed tomography/computed tomography (SPECT/CT) is a molecular imaging test that allows for the differentiation of benign renal oncocytomas and hybrid oncocytomic/chromophobe tumours apart from malignant renal cell carcinomas on the basis of differences in mitochondrial content as well as multidrug resistant pump expression. Herein, we review the principles of ^99mTc-sestamibi SPECT/CT administration and image interpretation for the purpose of renal mass characterization.

PD-1/PD-L1 interaction up-regulates MDR1/P-gp expression in breast cancer cells via PI3K/AKT and MAPK/ERK pathways

Programmed cell death ligand 1 (PD-L1) is an immunosuppressive molecule expressed on tumor cells. By interacting with programmed cell death-1 (PD-1) on T cells, it inhibits immune responses. Because PD-L1 expression on cancer cells increases their chemoresistance, we investigated the correlation between PD-L1 and multidrug resistance 1/ P-glycoprotein (MDR1/P-gp) expression in breast cancer cells. Analysis of breast cancer tissues using tissue microarrays revealed a significant correlation between PD-L1 and MDR1/P-gp protein levels. Increased expression of PD-L1 was associated with lymph node metastasis and histological tumor grade. In addition, interaction of PD-L1 with PD-1 induced phosphorylation of AKT and ERK, resulting in the activation of PI3K/AKT and MAPK/ERK pathways and increased MDR1/P-gp expression in breast cancer cells. The PD-1/PD-L1 interaction also increased survival of breast cancer cells incubated with doxorubicin. These findings suggest that the PD-1/PD-L1 inhibition may increase chemotherapy efficacy by inhibiting the MDR1/P-gp expression in breast cancer cells.

Molecular Imaging of P-glycoprotein in Chemoresistant Tumors Using a Dual-Modality PET/Fluorescence Probe

Overexpression of P-glycoprotein (Pgp) has been considered a primary cause for multidrug resistance in a variety of cancers for three decades. However, clinical translation of Pgp targeted therapeutics has been hindered by lack of patient preselection based on the Pgp presence in tumors. We aim to develop a molecularly targeted probe for imaging tumoral Pgp in vivo with positron emission tomography (PET) and fluorescence, and to provide a tool for preselecting the patients with tumoral Pgp expression. Thus, a Pgp monoclonal antibody 15D3 was chemically modified with IRDye800 (IR800) and DOTA chelator. The specificity of the antibody conjugates DOTA-Pab-IR800 was verified in Pgp-expressing 3T3-MDR1 and control 3T3 cells. After radiolabeling with ⁶⁴Cu, the probe was applied in small animal PET imaging of Pgp in a mouse xenograft model of NCI/ADR-Res cells, which are chemoresistant through overexpression of Pgp. Quantification analysis of the PET images demonstrated that the tumor uptake of the radioactive probe was 9.9 ± 1.4, 12.1 ± 1.2, and 10.5 ± 1.0%ID/g at 4, 24, and 48 h post injection. The tumor-to-muscle ratio was 20.9 at 48 h post injection based on biodistribution studies. Fluorescence imaging was performed following PET experiments, and it demonstrated excellent tumor accumulation of this dual-modality probe in the NCI/ADR-Res tumors. Further, an image-guided surgery was successfully performed using the fluorescence modality of the probe, demonstrating potential utility of this probe in image-guided surgical removal of Pgp-positive drug resistant tumors in the patients. In conclusion, this study clearly demonstrated that the Pgp-targeted antibody probe, ⁶⁴Cu-DOTA-Pab-IR800, could provide a promising diagnosis tool for detection of Pgp-expressing tumors in vivo.

Mathematical Simulation of Transport Kinetics of Tumor-Imaging Radiopharmaceutical 99mTc-MIBI

The proposed model describes in a quality way the process of tumor-imaging radiopharmaceutical ^99mTc-MIBI distribution with taking into account radiopharmaceutical accumulation, elimination, and radioactive decay. The dependencies of concentration versus the time are analyzed. The model can be easily tested by the concentration data of the radioactive pharmaceuticals in the blood measured at early time point and late time point of the scanning, and the obtained data can be used for determination of the washout rate coefficient which is one of the existing oncology diagnostics methods.

Bench to bedside molecular functional imaging in translational cancer medicine: to image or to imagine?

Ongoing research on malignant and normal cell biology has substantially enhanced the understanding of the biology of cancer and carcinogenesis. This has led to the development of methods to image the evolution of cancer, target specific biological molecules, and study the anti-tumour effects of novel therapeutic agents. At the same time, there has been a paradigm shift in the field of oncological imaging from purely structural or functional imaging to combined multimodal structure-function approaches that enable the assessment of malignancy from all aspects (including molecular and functional level) in a single examination. The evolving molecular functional imaging using specific molecular targets (especially with combined positron-emission tomography [PET] computed tomography [CT] using 2- [(18)F]-fluoro-2-deoxy-D-glucose [FDG] and other novel PET tracers) has great potential in translational research, giving specific quantitative information with regard to tumour activity, and has been of pivotal importance in diagnoses and therapy tailoring. Furthermore, molecular functional imaging has taken a key place in the present era of translational cancer research, producing an important tool to study and evolve newer receptor-targeted therapies, gene therapies, and in cancer stem cell research, which could form the basis to translate these agents into clinical practice, popularly termed "theranostics". Targeted molecular imaging needs to be developed in close association with biotechnology, information technology, and basic translational scientists for its best utility. This article reviews the current role of molecular functional imaging as one of the main pillars of translational research.

Positron emission tomography diagnostic imaging in multidrug-resistant hepatocellular carcinoma: focus on 2-deoxy-2-(18F)Fluoro-D-Glucose

Hepatocellular carcinoma (HCC) is one of the most lethal cancers worldwide. Surgical resection and liver transplantation are still the best options for treatment. Nevertheless, as the number of patients who may benefit from these therapies is limited, alternative therapies have been developed, including chemotherapy. However, partly due to the expression of multidrug resistance (MDR) proteins, it has been found that HCC is a highly chemoresistant tumor. The major family of MDR proteins is the ATP-binding cassette (ABC) transporter superfamily, which includes P-glycoprotein (Pgp) and MDR-associated protein 1 (MRP1). Positron emission tomography using the radiolabeled analog of glucose, 2-deoxy-2-((18)F)fluoro-D-glucose ([(18)F]FDG), has been used in diagnostic imaging of various types of tumors. Clinical studies are inconsistent but experimental studies have shown that [(18)F]FDG uptake is associated with tumor grade and is inversely proportional to Pgp expression in HCC. These studies unveil that [(18)F]FDG can be a substrate of Pgp, although that relationship remains unclear. This review sums up the relationship between MDR expression in HCC, and [(18)F]FDG uptake by tumor cells, showing that this radiopharmaceutical may provide a useful tool for the study of chemoresistance in HCC, and that the use of this marker may contribute to the therapeutic choice on this highly aggressive tumor.

Imaging of Tumor Angiogenesis for Radiologists--Part 2: Clinical Utility

Angiogenesis is a key cancer hallmark involved in tumor growth and metastasis development. Angiogenesis and tumor microenvironment significantly influence the response of tumors to therapies. Imaging techniques have changed our understanding of the process of angiogenesis, the resulting vascular performance, and the tumor microenvironment. This article reviews the status and potential clinical value of the imaging modalities used to assess the status of tumor vasculature in vivo, before, during, and after treatment.

Establishment of paclitaxel-resistant breast cancer cell line and nude mice models, and underlying multidrug resistance mechanisms in vitro and in vivo

BACKGROUND

Breast cancer is a common malignant tumor which affects health of women and multidrug resistance (MDR) is one of the main factors leading to failure of chemotherapy. This study was conducted to establish paclitaxel-resistant breast cancer cell line and nude mice models to explore underlying mechanisms of MDR.

METHODS

The breast cancer drug-sensitive cell line MCF-7 (MCF-7/S) was exposed in stepwise escalating paclitaxel (TAX) to induce a resistant cell line MCF-7/TAX. Cell sensitivity to drugs and growth curves were measured by MTT assay. Changes of cell morphology and ultrastructure were examined by optical and electron microscopy. The cell cycle distribution was determined by flow cytometry. Furthermore, expression of proteins related to breast cancer occurrence and MDR was tested by immunocytochemistry. In Vivo, nude mice were injected with MCF-7/S and MCF-7/TAX cells and weights and tumor sizes were observed after paclitaxel treatment. In addition, proteins involved breast cancer and MDR were detected by immunohistochemistry.

RESULTS

Compared to MCF-7/S, MCF-7/TAX cells had a higher resistance to paclitaxel, cross-resistance and prolonged doubling time. Moreover, MCF-7/TAX showed obvious alterations of ultrastructure. Estrogen receptor (ER) expression was low in drug resistant cells and tumors while expression of human epidermal growth factor receptor 2 (HER2) and Ki-67 was up-regulated. P-glycoprotein (P-gp), lung resistance-related protein (LRP) and glutathione-S-transferase-π (GST-π) involved in the MDR phenotype of resistant cells and tumors were all overexpressed.

CONCLUSION

The underlying MDR mechanism of breast cancer may involve increased expression of P-gp, LRP and GST-π.

In vivo imaging of multidrug resistance using a third generation MDR1 inhibitor

Cellular up-regulation of multidrug resistance protein 1 (MDR1) is a common cause for resistance to chemotherapy; development of third generation MDR1 inhibitors-several of which contain a common 6,7-dimethoxy-2-phenethyl-1,2,3,4-tetrahydroisoquinoline substructure-is underway. Efficacy of these agents has been difficult to ascertain, partly due to a lack of pharmacokinetic reporters for quantifying inhibitor localization and transport dynamics. Some of the recent third generation inhibitors have a pendant heterocycle, for example, a chromone moiety, which we hypothesized could be converted to a fluorophore. Following synthesis and teasing of a small set of analogues, we identified one lead compound that can be used as a cellular imaging agent that exhibits structural similarity and behavior akin to the latest generation of MDR1 inhibitors.

Role and mechanism of Twist1 in modulating the chemosensitivity of FaDu cells

Multidrug resistance (MDR) is one of the most important obstacles affecting the efficacy of chemotherapy treatments for numerous types of cancer. In the present study, we have demonstrated the possible function of Twist1 in the chemosensitivity of head and neck squamous cell carcinoma (HNSCC) and have identified that its mechanism maybe associated with MDR1/P-gp regulation. To investigate this, the hypopharyngeal cancer cell line, FaDu, and its MDR cell line induced by taxol, FaDu/T, were employed. Stable transfectants targeted to Twist1 overexpression and Twist1 silencing based on FaDu were also conducted. Morphological observation, flow cytometry, reverse transcription-polymerase chain reaction (RT-PCR), western blotting and laser scanning confocal microscope detection were utilized to detect the associations between Twist1 and the chemosensitivity of FaDu cells. Our results demonstrated that Twist1 and MDR1/P-gp were upregulated in FaDu/T cells in a MDR dose-dependent manner. The anti-apoptotic capabilities of FaDu/T cells were enhanced during MDR progression, with apoptosis-related proteins (Bcl-2, Bax, activated caspase-3 and caspase-9) changing to resist apoptosis. Twist1 overexpression decreased the sensitivity of cells to taxol as revealed by a significant increase in MDR1/P-gp and IC₅₀ (P<0.05). This overexpression also enhanced the resistance to apoptosis, with apoptotic proteins changing to resist cell death, and inhibited Ca²⁺ release induced by taxol (P<0.05). Detections in Twist1 silencing cells also confirmed this result. This study provided evidence that alterations of Twist1 expression modulates the chemosensitivity of FaDu cells to taxol. Therefore, Twist1 knockdown may be a promising treatment regimen for advanced hypopharyngeal carcinoma patients with MDR.

Astragalus polysaccharides can regulate cytokine and P-glycoprotein expression in H22 tumor-bearing mice

AIM: To investigate the adjunct anticancer effect of Astragalus polysaccharides in H22 tumor-bearing mice.

METHODS: To establish a solid tumor model, 5.0 × 10⁶/mL H22 hepatoma cells were inoculated subcutaneously into the right armpit region of Kunming mice (6-12 wk old, 18-22 g). When the tumors reached a size of 100 mm³, the animals were treated as indicated, and the mice were randomly assigned to seven groups (n = 10 each). After ten days of treatment, blood samples were collected from mouse eyes, and serum was harvested by centrifugation. Mice were sacrificed, and the whole body, tumor, spleen and thymus were weighed immediately. The rate of tumor inhibition and organ indexes were calculated. The expression levels of serum cytokines, P-glycoprotein (P-GP) and multidrug resistance (MDR) 1 mRNA in tumor tissues were detected using enzyme-linked immunosorbent assay, Western blotting, and quantitative myeloid-derived suppressor cells reverse transcription-polymerase chain reaction, respectively.

RESULTS: The tumor inhibition rates in the treatment groups of Adriamycin (ADM) + Astragalus polysaccharides (APS) (50 mg/kg), ADM + APS (100 mg/kg), and ADM + APS (200 mg/kg) were significantly higher than in the ADM group (72.88% vs 60.36%, P = 0.013; 73.40% vs 60.36%, P = 0.010; 77.57% vs 60.36%, P = 0.001). The spleen indexes of the above groups were also significantly higher than in the ADM group (0.65 ± 0.22 vs 0.39 ± 0.17, P = 0.023; 0.62 ± 0.34 vs 0.39 ± 0.17, P = 0.022; 0.67 ± 0.20 vs 0.39 ± 0.17, P = 0.012), and the thymus indexes of the ADM + APS (100 mg/kg) and ADM + APS (200 mg/kg) groups were significantly higher than in the ADM group (0.20 ± 0.06 vs 0.13 ± 0.04, P = 0.029; 0.47 ± 0.12 vs 0.13 ± 0.04, P = 0.000). APS was found to exert a synergistic anti-tumor effect with ADM and to alleviate the decrease in the sizes of the spleen and thymus induced by AMD. The expression of interleukin-1α (IL-1α), IL-2, IL-6, and tumor necrosis factor-α (TNF-α) was significantly higher in the ADM + APS (50 mg/kg), ADM + APS (100 mg/kg) and ADM + APS (200 mg/kg) groups than in the ADM group; and IL-10 was significantly lower in the above groups than in the ADM group. APS could increase IL-1α, IL-2, IL-6, and TNF-α expression and decrease IL-10 levels. Compared with the ADM group, APS treatment at a dose of 50-200 mg/kg could down-regulate MDR1 mRNA expression in a dose-dependent manner (0.48 ± 0.13 vs 4.26 ± 1.51, P = 0.000; 0.36 ± 0.03 vs 4.26 ± 1.51, P = 0.000; 0.21 ± 0.04 vs 4.26 ± 1.51, P = 0.000). The expression level of P-GP was significantly lower in the ADM + APS (200 mg/kg) group than in the ADM group (137.35 ± 9.20 mg/kg vs 282.19 ± 20.54 mg/kg, P = 0.023).

CONCLUSION: APS exerts a synergistic anti-tumor effect with ADM in H22 tumor-bearing mice. This may be related to its ability to enhance the expression of IL-1α, IL-2, IL-6, and TNF-α, decrease IL-10, and down-regulate MDR1 mRNA and P-GP expression levels.

Effects of Astragalus polysaccharides on P-glycoprotein efflux pump function and protein expression in H22 hepatoma cells in vitro

Background

Astragalus polysaccharides (APS) are active constituents of Astragalus membranaceus. They have been widely studied, especially with respect to their immunopotentiating properties, their ability to counteract the side effects of chemotherapeutic drugs, and their anticancer properties. However, the mechanism by which APS inhibit cancer and the issue of whether that mechanism involves the reversal of multidrug resistance (MDR) is not completely clear. The present paper describes an investigation of the effects of APS on P-glycoprotein function and expression in H22 hepatoma cell lines resistant to Adriamycin (H22/ADM).

Methods

H22/ADM cell lines were treated with different concentrations of APS and/or the most common chemotherapy drugs, such as Cyclophosphamid, Adriamycin, 5-Fluorouracil, Cisplatin, Etoposide, and Vincristine. Chemotherapeutic drug sensitivity, P-glycoprotein function and expression, and MDR1 mRNA expression were detected using MTT assay, flow cytometry, Western blotting, and quantitative RT-PCR.

Results

When used alone, APS had no anti-tumor activity in H22/ADM cells in vitro. However, it can increase the cytotoxicity of certain chemotherapy drugs, such as Cyclophosphamid, Adriamycin, 5-Fluorouracil, Cisplatin, Etoposide, and Vincristine, in H22/ADM cells. It acts in a dose-dependent manner. Compared to a blank control group, APS increased intracellular Rhodamine-123 retention and decreased P-glycoprotein efflux function in a dose-dependent manner. These factors were assessed 24 h, 48 h, and 72 h after administration. APS down regulated P-glycoprotein and MDR1 mRNA expression in a concentration-dependent manner within a final range of 0.8–500 mg/L and in a time-dependent manner from 24–72 h.

Conclusion

APS can enhance the chemosensitivity of H22/ADM cells. This may involve the downregulation of MDR1 mRNA expression, inhibition of P-GP efflux pump function, or both, which would decrease the expression of the MDR1 protein.

Novel oncologic drugs: what they do and how they affect images

Targeted therapies are designed to interfere with specific aberrant biologic pathways involved in tumor development. The main classes of novel oncologic drugs include antiangiogenic drugs, antivascular agents, drugs interfering with EGFR-HER2 or KIT receptors, inhibitors of the PI3K/Akt/mTOR pathway, and hormonal therapies. Cancer cells usurp normal signal transduction pathways used by growth factors to stimulate proliferation and sustain viability. The interaction of growth factors with their receptors activates different intracellular pathways affecting key tumor biologic processes such as neoangiogenesis, tumor metabolism, and tumor proliferation. The response of tumors to anticancer therapy can be evaluated with anatomic response assessment, qualitative response assessment, and response assessment with functional and molecular imaging. Angiogenesis can be measured by means of perfusion imaging with computed tomography and magnetic resonance (MR) imaging. Diffusion-weighted MR imaging allows imaging evaluation of tumor cellularity. The main imaging techniques for studying tumor metabolism in vivo are positron emission tomography and MR spectroscopy. Familiarity with imaging findings secondary to tumor response to targeted therapies may help the radiologist better assist the clinician in accurate evaluation of tumor response to these anticancer treatments. Functional and molecular imaging techniques may provide valuable data and augment conventional assessment of tumor response to targeted therapies. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.317115108/-/DC1.