Evaluation of the Metabolic Response to Cyclopamine Therapy in Pancreatic Cancer Xenografts Using a Clinical PET-CT System

Pharmacokinetics of Veratramine and Jervine from Alcohol Extracts of Radix Veratri

Background

Chinese Materia Medica and Jiangsu New Medical College record that Radix Veratri root is Liliaceae Veratrum taliense Loses. f. and the root of Veratrum stenophyllum Diels. According to traditional Chinese medicine (TCM) example, Radix Veratri is a Liliaceae plant Veratrum taliense. Another literature pointed out that the aliases of Veratrum taliense and Veratrum angustifolia are both Radix Veratri, and their effects are basically the same. The main active ingredient of Veratrum is veratramine, of which veratramine and Jervine are higher in content, reaching 24.60% and 21.28% of the total alkaloids, respectively. Veratrum alkaloids are both toxic and effective ingredients. In addition to its good clinical efficacy, attention should also be paid to its pharmacokinetic characteristics in vivo. It is particularly important to study the pharmacokinetic characteristics of veratramine and Jervine in vivo.

Objective

The goal of this study was to develop a simple and effective method for measuring veratramine and Jervine in rat plasma at the same time. This method was used to study the pharmacokinetic characteristics of veratramine and Jervine in the alcohol extract of Radix Veratri in rats, to provide a reasonable basis for the clinical use of Radix Veratri.

Methods

Eighteen SD rats were randomly assigned into three groups, half male and half female, and were given 0.04 g/kg, 0.08g/kg, and 0.16 g/kg Radix Veratri alcohol extract, respectively. Blood samples were collected at different time points and were analyzed by LC-MS/MS after protein precipitation. Bullatine was set as the internal standard; the plasma samples were extracted with ethyl acetate. After the sample was processed, acetonitrile-10 mM ammonium acetate, whose pH was adjusted to 8.8 with ammonia water, was taken as the mobile phase. Veratramine quantitative ion pair was 410.1⟶295.1m/z, Jervine quantitative ion pair was 426.2⟶114.1m/z, and Bullatine B (IS) quantitative ion pair was 438.2⟶420.1m/z. In the positive ion mode, the multireaction monitoring (MRM) mode was used to determine the blood concentration of veratramine and Jervine. DAS 3.3.0 was used to calculate the relevant pharmacokinetic parameters.

Results

Veratramine had a good linear relationship in the concentration range of 0.0745~18.2 ng/mL, and that of Jervine was 1.11~108 ng/mL. The correlation coefficient r of three consecutive batches of the standard curve was greater than 0.995. Veratramine's lower quantification limit was 0.745 ng/mL, Jervine's was 1.11 ng/mL, and precision and accuracy were both less than 15%. The accuracy of veratramine was between 88.96% and 101.85%, and the accuracy of Jervine was between 92.96% and 104.50%. This method was adopted for the pharmacokinetic study of alcohol extracts of Radix Veratri. The results showed that only C_max of veratramine female rats did not show linear kinetic characteristics in the dose range of Radix Veratri alcohol extract from 0.04 g/kg to 0.16 g/kg. For AUC_0‐t and C_max of veratramine and Jervine, it could not determine whether the Radix Veratri alcohol extract showed linear kinetic characteristics within the dosage range of 0.04 g/kg~0.16 g/kg. Veratramine and Jervine showed obvious gender differences in the absorption and elimination stages. The absorption rate of veratramine and Jervine by male mice was about 10 times higher than that of female mice, and the elimination rate of male mice is about 20 times lower than that of female mice. It was suggested that the clinical application of the steroidal alkaloids veratramine and Jervine in Radix Veratri required rational use of drugs based on gender.

Conclusion

An LC-MS/MS analysis method suitable for the pharmacokinetic study of veratramine and Jervine in Radix Veratri in SD rats was established to provide a basis for in vivo pharmacokinetic studies. The pharmacokinetic characteristics of veratramine and Jervine in the alcohol extract of Radix Veratri were significantly different in female and male rats. During the clinical use of Radix Veratri, it should pay close attention to the obvious gender differences that may occur after the medication.

Efficacy Screening of Gloriosa Superba Extracts in a Murine Pancreatic Cancer Model Using (18)F-FDG PET/CT for Monitoring Treatment Response

PURPOSE

In vivo efficacy of two herbal extracts of Gloriosa superba L. (Colchicaceae) was investigated in a murine pancreatic tumor model by tumor volume measurements and Positron Emission Tomography (PET) imaging using 2-deoxy-2-[(18)F]fluoro-d-glucose ((18)F-FDG).

MATERIALS AND METHODS

A crude extract of G. superba (GS) seeds rich in colchicine and a colchicine-poor extract (GS2B) containing mostly colchicoside as a putative prodrug were prepared. PANC02-bearing C57BL/6 mice were treated with either placebo, gemcitabine, or one of the extracts (three different doses) for 10 days. Tumor volume measurements were performed daily during treatment and additionally (18)F-FDG Positron emission tomography/computed tomography was acquired at baseline and after 7 days of treatment. Ki-67 and cleaved caspase-3 immunostaining was performed on the resected tumors.

RESULTS

After 7 days of treatment, a dose-dependent tumor growth inhibition of both extracts was observed with the highest in vivo response at the highest dose of GS and GS2B and gemcitabine. A positive significant correlation was found between Ki-67 scores and relative tumor volumes (RTV), and a negative significant correlation between caspase-3 staining scores and RTV. A decrease in (18)F-FDG uptake was clearly observed in all treatment groups.

CONCLUSIONS

The therapeutic efficacy of the two different herbal extracts was demonstrated in an in vivo pancreatic tumor model. (18)F-FDG PET was able to detect an early response as overall lower (18)F-FDG uptake was measured in the treated groups.

The conflicting roles of tumor stroma in pancreatic cancer and their contribution to the failure of clinical trials: a systematic review and critical appraisal

A nearly universal feature of pancreatic ductal adenocarcinoma (PDAC) is an extensive presence of activated stroma. This stroma is thought to aid in various tumor-promoting processes and hampers response to therapy. Here, we aim to evaluate the evidence that supports this role of the stroma in PDAC with functional experiments in relevant models, discuss the clinical trials that have aimed to target the stroma in this disease, and examine recent work that explains why these clinical trials based on stroma-targeting strategies have thus far not achieved the expected success. We systematically searched PubMed through August 2014 with no restrictions to identify published peer-reviewed research articles assessing the effect of targeting the stroma on tumor growth or metastases in preclinical animal models. Five hundred and thirty articles were extracted of which 31 were included in the analysis. Unfortunately, due to the large variety in models and outcome measures, we could not perform a meta-analysis of our data. We find that despite an abundance of positive outcomes reported in previous studies on stroma targeting, a strong discrepancy exists with the outcomes of clinical trials and the more recent preclinical work that is in line with these trials. We explain the incongruities by the duration of stroma targeting and propose that chronic stroma targeting treatment is possibly detrimental in the treatment of this disease.

In vivo18F-fluorodeoxyglucose-positron emission tomography/computed tomography imaging of pancreatic tumors in a transgenic rat model carrying the human KRASG12V oncogene

A novel KRAS-mediated transgenic rat model has previously been demonstrated, in which animals develop multiple pancreatic ductal adenocarcinoma (PDAC) that is histologically similar to human PDAC within two weeks. Positron emission tomography (PET)/computed tomography (CT) is commonly used for the diagnosis and staging of PDAC in humans, and can be adopted for optimal use in animal experiments. The aim of the present study was to evaluate the carcinogenic process in a rat pancreatic carcinoma model using small-animal multimodality imaging systems. The utility of fluorodeoxyglucose (FDG)-PET/CT in detecting the location and size of PDAC during tumor development in the present transgenic rat model was assessed. A small animal multimodality PET/CT system and contrast-enhanced CT (CECT) system were used for the imaging analysis of KRAS^G12V male transgenic rats (n=6), which developed pancreatic tumors following the administration of an injection of Cre recombinase (Cre)-carrying adenovirus. Laparotomies performed at six weeks post-treatment revealed that all three (100%) Cre-expressing rats developed pancreatic tumors that were <2 mm in diameter, none of which were detected by ¹⁸F-FDG PET/CT or CECT. At eight weeks post-treatment, the pancreatic tumors were heterogeneously visualized by ¹⁸F-FDG-PET/CT and CECT in two of the three rats. Furthermore, the autopsies confirmed that all three rats had developed pancreatic tumors. These novel findings provide evidence that the FDG-PET/CT imaging system is a valuable tool for the evaluation of the carcinogenic process, and one which may aid in treatment and preventive methods for pancreatic tumors in mammalian models. A limitation associated with the early detection of PDACs warrants further investigation.

Exosomal lipids induce human pancreatic tumoral MiaPaCa-2 cells resistance through the CXCR4-SDF-1α signaling axis

We previously reported that exosomes secreted by human pancreatic tumor cells induce cell death through the inhibition of the Notch-1 survival pathway (Ristorcelli et al., 2009). We demonstrated that exosomal lipids evoked apoptosis of human pancreatic cancer SOJ-6 cells. Based on the lipid composition of efficient exosomes we designed Synthetic Exosome-Like Nanoparticles (SELN) in which the ratio ordered lipids versus disordered lipids was equal to 6.0 (SELN6.0). These SELN decreased SOJ-6 cells survival by inhibiting the Notch-1 pathway. However MiaPaCa-2 cells were resistant to exosomes (Ristorcelli et al., 2008) and to SELN6.0 (Beloribi et al.,2012). In this paper we aimed at deciphering the reason(s) of this resistance. We observed, in presence of SELN6.0, that the expression of the Notch IntraCytoplasmic Domain (NICD) decreases in MiaPaCa-2 cells but neither Hes-1, the nuclear target of NICD, nor the ratio Bax/Bcl-2 were affected. We further showed that in MiaPaCa-2 cells SELN6.0 induced the activation of NF-kB, which promotes the expression and the secretion of SDF-1α. This chemokine interacts with its receptor CXCR4 on MiaPaCa-2 cells and activates the Akt survival pathway protecting cells from death. This activation process promoted by exosomal lipids could have implications in tumor progression and drug resistance.

(18)F-fluorodeoxyglucose uptake and tumor hypoxia: revisit (18)f-fluorodeoxyglucose in oncology application

This study revisited ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake and its relationship to hypoxia in various tumor models. METHODS: We generated peritoneal carcinomatosis and subcutaneous xenografts of colorectal cancer HT29, breast cancer MDA-MB-231, and non–small cell lung cancer A549 cell lines in nude mice. The partial oxygen pressure (pO₂) of ascites fluid was measured. ¹⁸F-FDG accumulation detected by digital autoradiography was related to tumor hypoxia visualized by pimonidazole binding and glucose transporter-1 (GLUT-1) in frozen tumor sections. RESULTS: Ascites pO₂ was 0.90 ± 0.53 mm Hg. Single cancer cells and clusters suspended in ascites fluid as well as submillimeter serosal tumors stained positive for pimonidazole and GLUT-1 and had high ¹⁸F-FDG uptake. In contrast, ¹⁸F-FDG uptake was significantly lower in normoxic portion (little pimonidazole binding or GLUT-1 expression) of larger serosal tumors or subcutaneous xenografts, which was not statistically different from that in the liver. CONCLUSIONS: Glucose demand (¹⁸F-FDG uptake) in severely hypoxic ascites carcinomas and hypoxic portion of larger tumors is significantly higher than in normoxic cancer cells. Warburg effect originally obtained from Ehrlich ascites carcinoma may not apply to normoxic cancer cells. Our findings may benefit the better understanding of ¹⁸F-FDG PET in oncology application.

Antidiabetic Drug Metformin Prevents Progression of Pancreatic Cancer by Targeting in Part Cancer Stem Cells and mTOR Signaling

Epidemiologic studies have shown that diabetes mellitus is associated positively with increased risk of pancreatic ductal adenocarcinoma (PDAC), and recent meta-analysis studies showed that metformin, reduces the risk of pancreatic cancer (PC). We tested the effects of metformin on pancreatic intraepithelial neoplasia (PanIN) and their progression to PDAC in p48Cre/+.LSL-KrasG12D/+ transgenic mice. Mice fed control diet showed 80% and 62% incidence of PDAC in males and females, respectively. Male mice showed 20% and 26%, and female mice showed 7% and 0% PDAC incidence with 1000- and 2000-ppm metformin treatments, respectively. Both doses of metformin decreased pancreatic tumor weights by 34% to 49% (P < 0.03-0.001). The drug treatment caused suppression of PanIN 3 (carcinoma in situ) lesions by 28% to 39% (P < .002) and significant inhibition of carcinoma spread in the pancreas. The pancreatic tissue and/or serum of mice fed metformin showed a significant inhibition of mammalian target of rapamycin (mTOR), extracellular signal-regulated kinases (ERK), phosphorylated extracellular signal-regulated kinases (pErk), and insulin-like growth factor 1 (IGF-1) with an increase in phosphorylated 5' adenosine monophosphate kinase (pAMPK), tuberous sclerosis complex 1 (TSC1, TSC2), C-protein and an autophagy related protein 2 (ATG2). The cancer stem cell (CSC) markers were significantly decreased (P < 0.04-0.0002) in the pancreatic tissue. These results suggest that biologic effects of metformin are mediated through decreased CSC markers cluster of differentiation 44 (CD44 and CD133), aldehyde dehydrogenase isoform 1 (ALDH1), and epithelial cell adhesion molecule (EPCAM) and modulation of the mTOR signaling pathway. Our preclinical data indicate that metformin has significant potential for use in clinical trials for PC chemoprevention.

Combined Injection of (18)F-Fluorodeoxyglucose and 3'-Deoxy-3'-[(18)F]fluorothymidine PET Achieves More Complete Identification of Viable Lung Cancer Cells in Mice and Patients than Individual Radiopharmaceutical: A Proof-of-Concept Study

PURPOSE

The objective is to validate the combination of 3'-deoxy-3'-[(18)F]fluorothymidine ((18)F-FLT) and (18)F-fluorodeoxyglucose ((18)F-FDG) as a "novel" positron emission tomography (PET) tracer for better visualization of cancer cell components in solid cancers than individual radiopharmaceutical.

METHODS

Nude mice with subcutaneous xenografts of human non-small cell lung cancer A549 and HTB177 cells and patients with lung cancer were included. In ex vivo study, intratumoral radioactivity of (18)F-FDG, (18)F-FLT, and the cocktail of (18)F-FDG and (18)F-FLT detected by autoradiography was compared with hypoxia (by pimonidazole) and proliferation (by bromodeoxyuridine) in tumor section. In in vivo study, first, (18)F-FDG PET and (18)F-FLT PET were conducted in the same subjects (mice and patients) 10 to 14 hours apart. Second, PET scan was also performed 1 hour after one tracer injection; subsequently, the other was administered and followed the second PET scan in the mouse. Finally, (18)F-FDG and (18)F-FLT cocktail PET scan was also performed in the mouse.

RESULTS

When injected individually, (18)F-FDG highly accumulated in hypoxic zones and high (18)F-FLT in proliferative cancer cells. In case of cocktail injection, high radioactivity correlated with hypoxic regions and highly proliferative and normoxic regions. PET detected that intratumoral distribution of (18)F-FDG and (18)F-FLT was generally mismatched in both rodents and patients. Combination of (18)F-FLT and (18)F-FDG appeared to map more cancer tissue than single-tracer PET.

CONCLUSIONS

Combination of (18)F-FDG and (18)F-FLT PET imaging would give a more accurate representation of total viable tumor tissue than either tracer alone and would be a powerful imaging strategy for cancer management.