Therapeutic effect of rapamycin on gallbladder cancer in a transgenic mouse model

A comparison of diagnostic utility of new endoscopic scraper combined cell block method and conventional brush catheter for biliary tract cancer

Background/Aims

The sensitivities of endoscopic trans-papillary pathologic diagnosis of biliary tract cancer (BTC) are unsatisfactory. Recently, the diagnostic utility of the endoscopic scraper device, Trefle for biliary stricture has been reported. The Trefle can be guided to the target biliary stricture over the guidewire and is as easy to use as the conventional brush catheter (CBC). This study evaluated the efficacy and safety of Trefle-assisted tissue acquisition combined cell block method and CBC cytology for biliary strictures due to BTCs.

Methods

We retrospectively reviewed consecutive patients with biliary strictures in whom CBC cytology or Trefle-assisted tissue acquisition under endoscopic retrograde cholangiopancreatography was performed for suspected BTCs from January 2015 to June 2022 at our institution.

Results

173 patients (CBC group; n = 55, Trefle group; n = 118) were enrolled in this study. The sensitivity, specificity, and accuracy of CBC cytology for BTC were 68.3%/100%/76.4%. On the other hand, the sensitivity, specificity, and accuracy of Trefle-assisted tissue acquisition for BTC were 93.7%/95.7%/94.1%, showing superior sensitivity (p < 0.001) and accuracy (p = 0.002) compared to that of CBC.

Conclusions

Compared to CBC cytology, Trefle-assisted tissue acquisition has superior diagnostic performance while maintaining procedural simplicity and is considered useful for diagnosing malignant biliary stricture.

Common Pathogenetic Mechanisms Underlying Aging and Tumor and Means of Interventions

Recently, there has been an increase in the incidence of malignant tumors among the older population. Moreover, there is an association between aging and cancer. During the process of senescence, the human body suffers from a series of imbalances, which have been shown to further accelerate aging, trigger tumorigenesis, and facilitate cancer progression. Therefore, exploring the junctions of aging and cancer and searching for novel methods to restore the junctions is of great importance to intervene against aging-related cancers. In this review, we have identified the underlying pathogenetic mechanisms of aging-related cancers by comparing alterations in the human body caused by aging and the factors that trigger cancers. We found that the common mechanisms of aging and cancer include cellular senescence, alterations in proteostasis, microbiota disorders (decreased probiotics and increased pernicious bacteria), persistent chronic inflammation, extensive immunosenescence, inordinate energy metabolism, altered material metabolism, endocrine disorders, altered genetic expression, and epigenetic modification. Furthermore, we have proposed that aging and cancer have common means of intervention, including novel uses of common medicine (metformin, resveratrol, and rapamycin), dietary restriction, and artificial microbiota intervention or selectively replenishing scarce metabolites. In addition, we have summarized the research progress of each intervention and revealed their bidirectional effects on cancer progression to compare their reliability and feasibility. Therefore, the study findings provide vital information for advanced research studies on age-related cancers. However, there is a need for further optimization of the described methods and more suitable methods for complicated clinical practices. In conclusion, targeting aging may have potential therapeutic effects on aging-related cancers.

Precision modeling of gall bladder cancer patients in mice based on orthotopic implantation of organoid-derived tumor buds

Genetically engineered mice (GEM) are the gold standard for cancer modeling. However, strict recapitulation of stepwise carcinogenesis from a single tumor-initiating epithelial cell among genetically intact cells in adults is not feasible with the currently available techniques using GEM. In previous studies, we partially overcame this challenge by physically isolating organs from adult animals, followed by genetic engineering in organoids and subcutaneous inoculation in nude mice. Despite the establishment of suitable ex vivo carcinogenesis models for diverse tissues, tumor development remained ectopic and occurred under immunodeficient conditions. Further refinement was, therefore, necessary to establish ideal models. Given the poor prognosis and few models owing to the lack of gall bladder (GB)-specific Cre strain, we assumed that the development of authentic models would considerably benefit GB cancer research. Here, we established a novel model using GB organoids with mutant Kras and Trp53 loss generated in vitro by lentiviral Cre transduction and CRISPR/Cas9 gene editing, respectively. Organoid-derived subcutaneous tumor fragments were sutured to the outer surface of the GB in syngeneic mice, which developed orthotopic tumors that resembled human GB cancer in histological and transcriptional features. This model revealed the infiltration of similar subsets of immune cells in both subcutaneous and orthotopic tumors, confirming the appropriate immune environment during carcinogenesis. In addition, we accurately validated the in vivo efficacy of gemcitabine, a common therapeutic agent for GB cancer, in large cohorts. Taken together, this model may serve as a promising avatar of patients with GB cancer in drug discovery and precision medicine.

Overview of current targeted therapy in gallbladder cancer

Gallbladder cancer (GBC) is rare, but is the most malignant type of biliary tract tumor. Unfortunately, only a small population of cancer patients is acceptable for the surgical resection, the current effective regimen; thus, the high mortality rate has been static for decades. To substantially circumvent the stagnant scenario, a number of therapeutic approaches owing to the creation of advanced technologic measures (e.g., next-generation sequencing, transcriptomics, proteomics) have been intensively innovated, which include targeted therapy, immunotherapy, and nanoparticle-based delivery systems. In the current review, we primarily focus on the targeted therapy capable of specifically inhibiting individual key molecules that govern aberrant signaling cascades in GBC. Global clinical trials of targeted therapy in GBC are updated and may offer great value for novel pathologic and therapeutic insights of this deadly disease, ultimately improving the efficacy of treatment.

Functional and genomic characterization of three novel cell lines derived from a metastatic gallbladder cancer tumor

Background

Gallbladder cancer (GBC) is the most common tumor of the biliary tract. The incidence of GBC shows a large geographic variability, being particularly frequent in Native American populations. In Chile, GBC represents the second cause of cancer-related death among women. We describe here the establishment of three novel cell lines derived from the ascitic fluid of a Chilean GBC patient, who presented 46% European, 36% Mapuche, 12% Aymara and 6% African ancestry.

Results

After immunocytochemical staining of the primary cell culture, we isolated and comprehensively characterized three independent clones (PUC-GBC1, PUC-GBC2 and PUC-GBC3) by short tandem repeat DNA profiling and RNA sequencing as well as karyotype, doubling time, chemosensitivity, in vitro migration capability and in vivo tumorigenicity assay. Primary culture cells showed high expression of CK7, CK19, CA 19-9, MUC1 and MUC16, and negative expression of mesothelial markers. The three isolated clones displayed an epithelial phenotype and an abnormal structure and number of chromosomes. RNA sequencing confirmed the increased expression of cytokeratin and mucin genes, and also of TP53 and ERBB2 with some differences among the three cells lines, and revealed a novel exonic mutation in NF1. The PUC-GBC3 clone was the most aggressive according to histopathological features and the tumorigenic capacity in NSG mice.

Conclusions

The first cell lines established from a Chilean GBC patient represent a new model for studying GBC in patients of Native American descent.

Eukaryotic translation initiation factor 6 overexpression plays a major role in the translational control of gallbladder cancer

BACKGROUND

Gallbladder cancer (GBC) is a rare neoplasia of the biliary tract with high mortality rates and poor prognosis. Signs and symptoms of GBC are not specific and often arise at late stage of disease. For this reason, diagnosis is typically made when the cancer is already in advanced stages, and prognosis for survival is less than 5 years in 90% of cases. Biomarkers to monitor disease progression and novel therapeutic alternative targets for these tumors are strongly required. Commonly, dysregulated protein synthesis contributes to carcinogenesis and cancer progression. In this case, protein synthesis directs translation of specific mRNAs, and, in turn, promotes cell survival, invasion, angiogenesis, and metastasis of tumors. In eukaryotes, protein synthesis is regulated at its initiation, which is a rate-limiting step involving eukaryotic translation initiation factors (eIFs). We hypothesize that eIFs represent crossroads in the development of GBC, and might serve as potential biomarkers. The study focus was the role of eIF6 (an anti-association factor for the ribosomal subunits) in GBC.

METHODS

In human GBC samples, the expression of eIF6 was analyzed biochemically at the protein (immunohistochemistry, immunoblot analyses) and mRNA levels (qRT-PCR).

RESULTS

High levels of eIF6 correlated with shorter overall survival in biliary tract cancer (BTC) patients (n = 28). Immunohistochemical data from tissue microarrays (n = 114) demonstrated significantly higher expression levels of eIF6 in GBC compared to non-neoplastic tissue. Higher eIF6 expression on protein (immunoblot) and mRNA (qRT-PCR) level was confirmed by analyzing fresh frozen GBC patient samples (n = 14). Depletion of eIF6 (using specific siRNA-mediated knockdown) in Mz-ChA-2 and TFK-1 cell lines inhibited cell proliferation and induced apoptosis.

CONCLUSION

Our data indicates that eIF6 overexpression plays a major role in the translational control of GBC, and indicates its potential as a new biomarker and therapeutic target in GBC.

Usefulness of serum microRNA as a predictive marker of recurrence and prognosis in biliary tract cancer after radical surgery

Biliary tract cancer (BTC) is an aggressive type of malignant tumour. Even after radical resection, the risk of recurrence is still high, resulting in a poor prognosis. Here, we investigated the usefulness of serum miRNAs as predictive markers of recurrence and prognosis for patients with BTC after radical surgery using 66 serum samples that were collected at three time points from 22 patients with BTC who underwent radical surgery. Using microarray analysis, we successfully identified six specific miRNAs (miR-1225-3p, miR-1234-3p, miR1260b, miR-1470, miR-6834-3p, and miR-6875-5p) associated with recurrence and prognosis of BTC after radical surgery. In addition, using a combination of these miRNAs, we developed a recurrence predictive index to predict recurrence in patients with BTC after operation with high accuracy. Patients having higher index scores (≥ cut-off) had significantly worse recurrence-free survival (RFS) and overall survival (OS) than those with lower index scores (<cut-off). Furthermore, the index was an independent factor related to RFS and OS by univariate and multivariate analyses using a Cox hazard proportional model. Overall, our results provided compelling evidence for the potential usefulness of specific serum miRNAs as effective predictive tools for recurrence and prognosis in patients with BTC who underwent radical surgery.

Targeting the PI3K/AKT/mTOR pathway in biliary tract cancers: A review of current evidences and future perspectives

Biliary tract cancers (BTCs) are a group of invasive neoplasms, with increasing incidence and dismal prognosis. In advanced disease, the standard of care is represented by first-line chemotherapy with cisplatin and gemcitabine. In subsequent lines, no clear recommendations are currently available, highlighting the need for novel therapeutic approaches. The PI3K/AKT/mTOR pathway is a core regulator of cell metabolism, growth and survival, and is involved in BTCs carcinogenesis and progression. Mutations, gene copy number alterations and aberrant protein phosphorylation of PI3K, AKT, mTOR and PTEN have been thoroughly described in BTCs and correlate with poor survival outcomes. Several pre-clinical evidences state the efficacy of PI3K/AKT/mTOR pathway inhibitors in BTCs, both in vitro and in vivo. In the clinical setting, initial studies with rapamycin analogs have shown interesting activity with an acceptable toxicity profile. Novel strategies evaluating AKT and PI3K inhibitors have risen serious safety concerns, pointing out the need for improved patient selection and increased target specificity for the clinical development of these agents, both alone and in combination with chemotherapy. This review extensively describes the role of the PI3K/AKT/mTOR pathway in BTCs and examines the rationale of its targeting in these tumors, with particular focus on clinical activity, toxicities and perspectives on further development of PI3K/AKT/mTOR pathway inhibitors.

Targeting phosphoinositide-3-kinase pathway in biliary tract cancers: A remedial route?

Biliary tract cancers (BTC) are aggressive tumours with a low survival rate. At the advent of the genomic era, various genetic mutations in cell signalling pathways have been incriminated in carcinogenesis. Genomic analysis studies have connected main components of the phosphoinositide-3-kinase (PI3K) signalling pathway to BTC. PI3K pathway playing a central role in cell signalling and being deregulated in various tumours has been studied as a target for chemotherapy. Novel compounds have also been identified in preclinical trials that specifically target the PI3K pathway in BTCs, but these studies have not accelerated to clinical use. These novel compounds can be examined in upcoming studies to validate them as potential therapeutic agents, as further research is required to combat the growing need for adjuvant chemotherapy to successfully battle this tumour type. Furthermore, these molecules could also be used along with gemcitabine, cisplatin and 5-fluorouracil to improve sensitivity of the tumour tissue to chemotherapy. This review focuses on the basics of PI3K signalling, genetic alterations of this pathway in BTCs and current advancement in targeting this pathway in BTCs. It emphasizes the need for gene-based drug screening in BTC. It may reveal various novel targets and drugs for amelioration of survival in patients with BTC and serve as a stepping stone for further research.

Phase II study of everolimus (RAD001) monotherapy as first-line treatment in advanced biliary tract cancer with biomarker exploration: the RADiChol Study

Background

Advanced biliary tract cancers (BTCs) have a poor prognosis and limited treatment options. This exploratory phase II study aimed to evaluate the activity of the mTOR inhibitor everolimus in advanced BTC and explore prognostic biomarkers.

Methods

Patients with advanced BTCs, who had not received chemotherapy for advanced disease, were enroled to receive everolimus (10 mg daily). The primary endpoint was disease control rate (DCR) at 12 weeks. Secondary endpoints included overall response rate, progression-free survival (PFS), overall survival (OS) and adverse events. Activation status of the RAS and phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathways was assessed by DNA sequencing and immunohistochemistry on archival tumour tissue.

Results

The study enroled 27 patients and the DCR at 12 weeks was 48%. Median PFS was 5.5 months (95% confidence interval (CI): 2.1–10.0 months) and median OS was 9.5 months (95% CI: 5.5–16.6 months). DCR at 12 weeks was significantly worse for gall bladder carcinoma compared to other anatomical sites, and there was a trend towards a worsened PFS and OS. Treatment was well tolerated. KRAS (12%) and PIK3CA mutations (12%) were uncommon. Immunohistochemical staining for PI3K/AKT/mTOR pathways did not significantly correlate with outcome.

Conclusion

In unselected patients, everolimus demonstrated clinical activity as first-line monotherapy in advanced BTC.

K-Ras mutation and amplification status is predictive of resistance and high basal pAKT is predictive of sensitivity to everolimus in biliary tract cancer cell lines

Advanced biliary tract cancer (BTC) has a poor prognosis and limited treatment options. The PI3K/Akt/mTOR signalling pathway is hyperactivated in a subset of BTCs, and clinical activity of the mTOR inhibitor everolimus has been observed in some patients with BTC. The goal of this study was to identify biomarkers predictive of everolimus response. Twenty BTC cell lines were assessed for everolimus sensitivity with a spectrum of growth inhibitory responses observed. Molecular biomarkers of sensitivity and resistance were identified by interrogation of the activation status of the Ras/MAPK and PI3K/Akt/mTOR pathways. K-Ras mutations and/or amplifications were identified in 45% of cell lines and were associated with resistance to everolimus. Activating mutations in PIK3CA or loss of PTEN was not predictive of everolimus response; however, high basal levels of pAKT were associated with sensitivity, independent of Ras/MAPK pathway activation status. Notably, everolimus inhibited mTOR signalling to a similar extent in sensitive and resistant cell lines, suggesting that relative dependence on the mTOR pathway rather than the magnitude of pathway inhibition determines everolimus response. Consistent with the known limitations of rapalogs, everolimus induced feedback-mediated activation of AKT in BTC cell lines, which could be overcome by cotreatment with an AKT inhibitor or ATP-competitive mTORC1/mTORC2 inhibitors. However, both approaches failed to induce greater apoptosis compared to everolimus, and mTORC1/mTORC2 kinase inhibitors induced compensatory activation of pERK, identifying an inherent limitation of these agents in BTC cell lines. These findings suggest that future trials of everolimus in BTC would benefit from preselecting patients based on their K-Ras and PI3K/mTOR pathway activation status. The study also identifies strategies for enhancing inhibition of the PI3K/mTOR pathway in BTC cell lines.

Novel investigational therapies for treating biliary tract carcinoma

INTRODUCTION

Cholangiocarcinoma (CCA) is an epithelial cell malignancy arising from bile ducts and/or peribiliary glands. Even though it is considered as a rare neoplasm, its incidence is raising, particularly in developed countries. Prognosis is generally poor with few patients who present the inclusion criteria for surgery (the mainstay treatment for this tumour). Several genetic alterations potentially driving tumour progression have been described, representing a possible target for new compounds. Areas covered: A clinical trial search in Clinicaltrials.gov encompassing a literature search in PubMed and ASCO/ESMO Websites was undertaken in March 2016. Expert opinion: Notwithstanding a large number of drug tested, results are still disappointing. The main reasons could be the low number of patients enrolled in trials, and the lack of a patient selection based on the biological profile of the tumours. Potential active drugs could have been discharged simply because beneficial in a particular subgroup of patients and not in un unselected population. The future direction of the research should consider biomarker evaluation in order to describe the genetic alteration/s that drive tumour progression and aggressiveness and the mechanisms of drug resistance. Finally, it will be of great interest to consider the results of immunotherapy whenever available.

Rapamycin and WYE-354 suppress human gallbladder cancer xenografts in mice

Gallbladder cancer (GBC) is a highly malignant tumor characterized by a poor response to chemotherapy and radiotherapy. We evaluated the in vitro and in vivo antitumor efficacy of mTOR inhibitors, rapamycin and WYE-354. In vitro assays showed WYE-354 significantly reduced cell viability, migration and invasion and phospho-P70S6K expression in GBC cells. Mice harboring subcutaneous gallbladder tumors, treated with WYE-354 or rapamycin, exhibited a significant reduction in tumor mass. A short-term treatment with a higher dose of WYE-354 decreased the tumor size by 68.6% and 52.4%, in mice harboring G-415 or TGBC-2TKB tumors, respectively, compared to the control group. By contrast, treatment with a prolonged-low-dose regime of rapamycin almost abrogated tumor growth, exhibiting 92.7% and 97.1% reduction in tumor size, respectively, compared to control mice. These results were accompanied by a greater decrease in the phosphorylation status of P70S6K and a lower cell proliferation Ki67 index, compared to WYE-354 treated mice, suggesting a more effective mTOR pathway inhibition. These findings provide a proof of concept for the use of rapamycin or WYE-354 as potentially good candidates to be studied in clinical trials in GBC patients.

A potent therapeutics for gallbladder cancer by combinatorial inhibition of the MAPK and mTOR signaling networks

BACKGROUND

Gallbladder cancer (GBC) is the most common type of cancer with the worst prognosis among the bile duct cancers. There still remains a clear need for effective mechanism-based novel therapeutic approaches. A crosstalk between mitogen-activated protein kinase (MAPK) and the mammalian target of Rapamycin (mTOR) signaling pathways has been reported in several cancers. We hypothesized that targeting both pathways in combination will be a potent therapeutic for GBC.

METHODS

Expression of phospho-ERK and phospho-S6rp protein were evaluated by immunostaining in surgically resected GBC specimens (n = 30). GBC cell lines and a xenograft model were treated with CI-1040, an inhibitor of MEK (mitogen-activated protein kinase kinase) and RAD001, an inhibitor of mTOR, alone or in combination, and then, we examined the cell proliferation and tumor growth, cell cycle status, and apoptosis.

RESULTS

Analysis of human GBC tissues demonstrated that MAPK and mTOR signaling pathways were frequently coordinately dysregulated in one third of them. The combination therapy inhibited both signaling pathways and subsequently inhibited human GBC cell proliferation in vitro and xenograft tumor growth in vivo. Compared to the single treatment, the combination therapy significantly induced cell cycle arrest and apoptosis with decreased cyclin D1 expression.

CONCLUSIONS

The double blockade of MAPK and mTOR signaling pathways inhibits the signal crosstalk and shows anti-tumor activity, which can be a potent therapeutic for GBC, especially for the patients with hyperactivated signaling of both pathways.

Circulating MicroRNAs as Biomarkers in Biliary Tract Cancers

Biliary tract cancers (BTCs) are a group of highly aggressive malignant tumors with a poor prognosis. The current diagnosis is based mainly on imaging and intraoperative exploration due to brush cytology havinga low sensitivity and the standard markers, such as carcinoembryonic antigen (CEA) and carbohydrate 19-9 (CA19-9), not having enough sensitivity nor specificity to be used in a differential diagnosis and early stage detection. Thus, better non-invasive methods that can distinguish between normal and pathological tissue are needed. MicroRNAs (miRNAs) are small, single-stranded non-coding RNA molecules of ~20–22 nucleotides that regulate relevant physiological mechanisms and can also be involved in carcinogenesis. Recent studies have demonstrated that miRNAs are detectable in multiple body fluids, showing great stability, either free or trapped in circulating microvesicles, such as exosomes. miRNAs are ideal biomarkers that may be used in screening and prognosis in biliary tract cancers, aiding also in the clinical decisions at different stages of cancer treatment. This review highlights the progress in the analysis of circulating miRNAs in serum, plasma and bile as potential diagnostic and prognostic markers of BTCs.

p53 and rapamycin are additive

Mechanistic target of rapamycin (mTOR) is a kinase found in a complex (mTORC1) that enables macromolecular synthesis and cell growth and is implicated in cancer etiology. The rapamycin-FK506 binding protein 12 (FKBP12) complex allosterically inhibits mTORC1. In response to stress, p53 inhibits mTORC1 through a separate pathway involving cell signaling and amino acid sensing. Thus, these different mechanisms could be additive. Here we show that p53 improved the ability of rapamycin to: 1) extend mouse life span, 2) suppress ionizing radiation (IR)-induced senescence-associated secretory phenotype (SASP) and 3) increase the levels of amino acids and citric acid in mouse embryonic stem (ES) cells. This additive effect could have implications for cancer treatment since rapamycin and p53 are anti-oncogenic.

Novel therapeutic strategy targeting the Hedgehog signalling and mTOR pathways in biliary tract cancer

Background:

Activation of the PI3K/mTOR and Hedgehog (Hh) signalling pathways occurs frequently in biliary tract cancer (BTC). Crosstalk between these pathways occurs in other gastrointestinal cancers. The respective signalling inhibitors rapamycin and vismodegib may inhibit BTC synergistically and suppress cancer stem cells (CSCs).

Methods:

Gene expression profiling for p70S6k and Gli1 was performed with BTC cell lines. Tumour and pathway inhibitory effects of rapamycin and vismodegib were investigated in BTC preclinical models and CSCs.

Results:

Rapamycin and vismodegib synergistically reduced BTC cell viability and proliferation. This drug combination arrested BTC Mz-ChA-1 cells in the G1 phase but had no significant effect on the cell cycle of BTC Sk-ChA-1 cells. Combined treatment inhibited the proliferation of CSCs and ALDH-positive cells. Nanog and Oct-4 expression in CSCs was decreased by the combination treatment. Western blotting results showed the p-p70S6K, p-Gli1, p-mTOR, and p-AKT protein expression were inhibited by the combination treatment in BTC cells. In an Mz-ChA-1 xenograft model, combination treatment resulted in 80% inhibition of tumour growth and prolonged tumour doubling time. In 4 of 10 human BTC specimens, tumour p-p70S6K and Gli1 protein expression levels were decreased with the combination treatment.

Conclusions:

Targeted inhibition of the PI3K/mTOR and Hhpathways indicates a new avenue for BTC treatment with combination therapy.

Expression of insulin-like growth factor I receptor as a biomarker for predicting prognosis in biliary tract cancer patients

Carcinomas of the gallbladder (GBCa) and bile ducts are aggressive tumors with poor survival and it is, therefore, essential to elucidate the molecular mechanisms of the various signaling pathways in order to develop effective therapies. In this study, tumor specimens from 40 GBCa patients, 12 extrahepatic bile duct carcinoma patients and 26 intrahepatic bile duct carcinoma patients from the USA and Japan were investigated for insulin-like growth factor I receptor (IGF-IR), mammalian target of rapamycin (mTOR) and rapidly accelerated fibrosarcoma-1 (Raf-1) expression by immunohistochemistry; in addition, the correlations with histological type, pathological stage and patient outcome were analyzed. Positive expression of IGF-IR, mTOR and Raf-1 were identified in 68, 73 and 85% of the specimens, respectively. There was no association with histological type and pathological stage, although the positive expression rate of Raf-1 was higher in advanced-stage GBCa. Moreover, patients with positive expression of IGF-IR exhibited significantly reduced survival compared to those with negative IGF-IR expression. In conclusion, IGF-IR, mTOR and Raf-1 were highly expressed in biliary tract cancer and targeted therapy against IGF-IR may be an effective strategy. Among these molecules, IGF-IR expression was found to be a useful biomarker for identifying patients who may benefit from additional treatment.

Targeting specific molecular pathways holds promise for advanced gallbladder cancer therapy

Gallbladder cancer is the most common and aggressive malignancy of the biliary tract. The complete surgical resection is the only potentially curative approach in early stage; however, most cases are diagnosed in advanced stages and the response to traditional chemotherapy and radiotherapy is extremely limited, with modest impact in overall survival. The recent progress in understanding the molecular alterations of gallbladder cancer has shown great promise for the development of more effective treatment strategies. This has mainly resulted from the identification of molecular alterations in relevant intracellular signaling pathways-Hedgehog, PI3K/AKT/mTOR, Notch, ErbB, MAPK and angiogenesis-which are potential tailored targets for gallbladder cancer patients. This review discusses the recent remarkable progress in understanding the molecular alterations that represent novel prognosis molecular markers and therapeutic targets for gallbladder cancer, which will provide opportunities for research and for developing innovative strategies that may enhance the benefit of conventional chemotherapy, or eventually modify the fatal natural history of this orphan disease.

Conversion to everolimus dramatically improves the prognosis of de novo malignancies after liver transplantation for alcoholic liver disease

De novo malignancies are a main cause for late death after liver transplantation (LT). Everolimus (ERL) is an immunosuppressive agent with antitumoral properties. The aim of the present retrospective study was to identify prognostic factors, including conversion to ERL, for patients presenting non-cutaneous de novo solid organ malignancy after LT for alcoholic cirrhosis. The study population consisted of 83 patients (presenting 100 tumors, including 75% of upper aerodigestive tract cancers), among the 398 patients who underwent LT for alcoholic cirrhosis in our center. After diagnosis, ERL was introduced in 38 patients and calcineurin-inhibitor was discontinued in 64.1% of them. Tumor stage was a significant prognostic factor with a one-yr survival at 82.6% for early stages, 63.4% for intermediate stages (N+) and 27.4% for disseminated diseases (p < 0.001). Associated relative risk factor was 2.202 (95% CI 1.044-4.644) for intermediate stages and 5.743 (95% CI 2.436-13.541) for metastatic stages. One- and five-yr survival was 77.4% and 35.2% in ERL group vs. 47.2% and 19.4% in the non-ERL group, respectively (p = 0.003). The relative risk factor for ERL was 0.447 (95%CI 0.257-0.778). Our results strongly suggest that conversion to ERL improves the prognosis of de novo malignancies after LT for alcoholic cirrhosis. Prospective studies are needed to confirm this benefit.

Rapamycin-Induced apoptosis in HGF-stimulated lens epithelial cells by AKT/mTOR, ERK and JAK2/STAT3 pathways

Hepatocyte growth factor (HGF) induced the proliferation of lens epithelial cells (LECs) and may be a major cause of posterior capsule opacification (PCO), which is the most frequent postoperative complication of cataract surgery. To date, several agents that can block LECs proliferation have been studied, but none have been used in clinic. Recently, accumulating evidence has suggested rapamycin, the inhibitor of mTOR (mammalian target of Rapamycin), was associated with the induction of apoptosis in LECs. The purpose of our study was to investigate the potential effects of rapamycin on HGF-induced LECs and the underlying mechanisms by which rapamycin exerted its actions. Using cell proliferation, cell viability and flow cytometric apoptosis assays, we found that rapamycin potently not only suppressed proliferation but also induced the apoptosis of LECs in a dose-dependent manner under HGF administration. Further investigation of the underlying mechanism using siRNA transfection revealed that rapamycin could promote apoptosis of LECs via inhibiting HGF-induced phosphorylation of AKT/mTOR, ERK and JAK2/STAT3 signaling molecules. Moreover, the forced expression of AKT, ERK and STAT3 could induce a significant suppression of apoptosis in these cells after treatment of rapamycin. Together, these findings suggested that rapamycin-induced apoptosis in HGF-stimulated LECs is accompanied by inhibition of AKT/mTOR, ERK and JAK2/STAT3 pathways, which supports its use to inhibit PCO in preclinical studies and provides theoretical foundation for future possible practice.

Activity and safety of RAD001 (everolimus) in patients affected by biliary tract cancer progressing after prior chemotherapy: a phase II ITMO study

BACKGROUND

Biliary tract cancer (BTC) is a highly lethal disease for which the best available therapy remains undetermined. The mammalian target of rapamycin (mTOR) pathway is up-regulated in several cancers, including BTC, and preclinical evidence indicates that mTOR inhibition may be effective in the treatment of BTC. We sought to evaluate the activity and tolerability of the mTOR inhibitor RAD001-everolimus-in patients with BTC progressing after prior chemotherapy.

PATIENTS AND METHODS

This was an open-label, single-arm, phase II study (EUDRACT 2008-007152-94) conducted in eight sites in Italy. Patients with locally advanced, metastatic or recurrent BTC progressing despite previous chemotherapy received a daily oral dose of everolimus 10 mg administered continuously in 28-day cycles. The two primary end points were disease control rate (DCR) and objective response rate (ORR). Secondary end points were progression-free survival (PFS), overall survival (OS) and time-to-progression (TTP).

RESULTS

Thirty-nine patients were enrolled. The DCR was 44.7%, and the ORR was 5.1%. One patient showed a partial response at 2 months and one patient showed a complete response sustained up to 8 months. The median (95% confidence interval) PFS was 3.2 (1.8-4.0) months, and the median OS was 7.7 (5.5-13.2) months. The median TTP was 2.0 (1.7-3.7) months. Most common toxicities were asthenia (43.6%), thrombocytopenia (35.9%), pyrexia (30.8%) and erythema, mainly of mild-to-moderate severity. Two patients required dose reduction due to adverse events.

CONCLUSION

Everolimus demonstrated a favourable toxicity profile and encouraging anti-tumour activity. Further trials are needed to establish the role of everolimus in the treatment of BTC. EUDRACT 2008-007152-94.

Inhibition of mTOR pathway attenuates migration and invasion of gallbladder cancer via EMT inhibition

Gallbladder cancer (GBC) is an aggressive disease in which epithelial-mesenchymal transition (EMT) plays a critical role. Whether inhibition of mTOR effects via EMT reversal in GBC remains unclear. Using genetic and pharmacologic inhibitions of mTOR, we investigated the changes of EMT levels in GBC cells. Expressions of EMT related genes were also studied. Migration and invasion assays were carried out and in vivo tumour metastasis mouse models were established. Circulating tumour DNA was quantified. We used EMT index (ratio of Vimentin/Ecadherin expression) to profile EMT levels. We found that inhibition of mTOR using shRNAs and rapamycin inhibited EMT in GBC-SD gallbladder cancer cells. Inhibition of mTOR inhibited EMT in GBC-SD cells in TGF-β-dependent manner, which was contributed majorly by mTORC2 inhibition. Rapamycin decreased invasiveness and migration of GBC-SD cells in vitro and in vivo. We have in the current study shown that rapamycin diminishes the ability of invasion and migration of GBC via inhibition of TGF-β-dependent EMT. Our findings contribute to the understanding of the carcinogenesis of GBC.

Molecular aspects of cholangiocarcinoma

Novel targets for therapeutic or chemopreventive approaches against cholangiocarcinoma (CCA) are urgently needed. In this review article, we discuss the molecular aspects of CCA including the role of erbB receptor tyrosine kinases (RTKs), downstream signaling pathways of these erbB RTKs, inflammatory mediators during gallbladder carcinogenesis and bile acids based on our study using a mouse model for human CCA (BK5.erbB2 mice) as well as additional information in the literature.

AKT/mTOR substrate P70S6K is frequently phosphorylated in gallbladder cancer tissue and cell lines

Background

Gallbladder carcinoma is a highly malignant tumor and a public health problem in some parts of the world. It is characterized by a poor prognosis and its resistance to radio and chemotherapy. There is an urgent need to develop novel therapeutic alternatives for the treatment of gallbladder carcinoma. The mammalian target of the rapamycin (mTOR) signaling pathway is activated in about 50% of human malignancies, and its role in gallbladder carcinoma has previously been suggested. In the present study, we investigated the phosphorylation status of the mTOR substrate p70S6K in preneoplastic and neoplastic gallbladder tissues and evaluated the effect of three mTOR inhibitors on cell growth and migration in gallbladder carcinoma cell lines.

Methods

Immunohistochemical staining of phospho-p70S6K was analyzed in 181 gallbladder carcinoma cases, classified according to lesion type as dysplasia, early carcinoma, or advanced carcinoma. Protein expression of AKT/mTOR members was also evaluated in eight gallbladder carcinoma cell lines by Western blot analysis. We selected two gallbladder carcinoma cell lines (G415 and TGBC-2TKB) to evaluate the effect of rapamycin, RAD001, and AZD8055 on cell viability, cell migration, and protein expression.

Results

Our results showed that phospho-p70S6K is highly expressed in dysplasia (66.7%, 12/18), early cancer (84.6%, 22/26), and advanced cancer (88.3%, 121/137). No statistical correlation was observed between phospho-p70S6K status and any clinical or pathological features, including age, gender, ethnicity, wall infiltration level, or histological differentiation (P < 0.05). In vitro treatment with rapamycin, RAD001, and AZD8055 reduced cell growth, cell migration, and phospho-p70S6K expression significantly in G-415 and TGBC-2TKB cancer cells (P < 0.001).

Conclusion

Our findings confirm the upregulation of this signaling pathway in gallbladder carcinoma and provide a rationale for the potential use of mTOR inhibitors as a therapeutic strategy for human gallbladder carcinoma.

Chronic inflammation and gallbladder cancer

Gallbladder cancer (GBC) is the most common biliary tract malignancy with an extremely poor prognosis. Epidemiological data have demonstrated that chronic inflammation resulting from infection of gallbladder or gallstones predispose individuals to GBC. Recent studies have begun to elucidate molecular mechanisms underlying the development of GBC in the setting of chronic inflammation. It is possible that persistently local inflammatory reactions may contribute to the development and progression of GBC through inducing genetic alterations, and subsequent promoting survival and proliferation of mutated sells, inhibiting apoptosis, stimulating angiogenesis and metastasis. This article reviews the current understanding of the involvement of chronic inflammation in gallbladder tumorigenesis.

Targeted inhibition of mammalian target of rapamycin (mTOR) enhances radiosensitivity in pancreatic carcinoma cells

The mammalian target of rapamycin (mTOR) is a protein kinase that regulates protein translation, cell growth, and apoptosis. Rapamycin (RPM), a specific inhibitor of mTOR, exhibits potent and broad in vitro and in vivo antitumor activity against leukemia, breast cancer, and melanoma. Recent studies showing that RPM sensitizes cancers to chemotherapy and radiation therapy have attracted considerable attention. This study aimed to examine the radiosensitizing effect of RPM in vitro, as well as its mechanism of action. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and colony formation assay showed that 10 nmol/L to 15 nmol/L of RPM had a radiosensitizing effects on pancreatic carcinoma cells in vitro. Furthermore, a low dose of RPM induced autophagy and reduced the number of S-phase cells. When radiation treatment was combined with RPM, the PC-2 cell cycle arrested in the G2/M phase of the cell cycle. Complementary DNA (cDNA) microarray and reverse transcription polymerase chain reaction (RT-PCR) revealed that the expression of DDB1, RAD51, and XRCC5 were downregulated, whereas the expression of PCNA and ABCC4 were upregulated in PC-2 cells. The results demonstrated that RPM effectively enhanced the radiosensitivity of pancreatic carcinoma cells.

Targeted therapy for biliary tract cancers

Biliary tract cancers (BTCs) are a heterogeneous group of malignancies, with a historically poor prognosis as a whole. Until recently, the development of effective therapeutics was hampered by the relatively low incidence, heterogeneity in patients and tumors, and correspondingly poor clinical trial enrollments. With the publication of the landmark phase III ABC-02 trial demonstrating the superiority of gemcitabine and cisplatin combination chemotherapy, the landscape changed for the development of new agents. Despite this progress, there are currently no approved targeted agents for BTC. This review will focus on recent developments in targeted therapeutics, directed against several key signaling pathways in BTC, including epidermal growth factor receptor, angiogenesis, and the mitogen-activated protein kinase pathway. Data from recent phase I and II trials will be discussed, along with a preview of upcoming trials involving targeted therapies.

Targeting LKB1 signaling in cancer

The serine/threonine kinase LKB1 is a master kinase involved in cellular responses such as energy metabolism, cell polarity and cell growth. LKB1 regulates these crucial cellular responses mainly via AMPK/mTOR signaling. Germ-line mutations in LKB1 are associated with the predisposition of the Peutz-Jeghers syndrome in which patients develop gastrointestinal hamartomas and have an enormously increased risk for developing gastrointestinal, breast and gynecological cancers. In addition, somatic inactivation of LKB1 has been associated with sporadic cancers such as lung cancer. The exact mechanisms of LKB1-mediated tumor suppression remain so far unidentified; however, the inability to activate AMPK and the resulting mTOR hyperactivation has been detected in PJS-associated lesions. Therefore, targeting LKB1 in cancer is now mainly focusing on the activation of AMPK and inactivation of mTOR. Preclinical in vitro and in vivo studies show encouraging results regarding these approaches, which have even progressed to the initiation of a few clinical trials. In this review, we describe the functions, regulation and downstream signaling of LKB1, and its role in hereditary and sporadic cancers. In addition, we provide an overview of several AMPK activators, mTOR inhibitors and additional mechanisms to target LKB1 signaling, and describe the effect of these compounds on cancer cells. Overall, we will explain the current strategies attempting to find a way of treating LKB1-associated cancer.

Antitumor effects of rapamycin in pancreatic cancer cells by inducing apoptosis and autophagy

Rapamycin (Rapa), an inhibitor of mammalian target of Rapamycin (mTOR), is an immunosuppressive agent that has anti-proliferative effects on some tumors. This study aims to investigate the effects of Rapa suppressing proliferation of pancreatic carcinoma PC-2 cells in vitro and its molecular mechanism involved in antitumor activities. MTT assays showed that the inhibition of proliferation of PC-2 cells in vitro was in a time- and dose-dependent manner. By using transmission electron microscopy, apoptosis bodies and formation of abundant autophagic vacuoles were observed in PC-2 cells after Rapa treatment. Flow cytometry assays also showed Rapa had a positive effect on apoptosis. MDC staining showed that the fluorescent density was higher and the number of MDC-labeled particles in PC-2 cells was greater in the Rapa treatment group than in the control group. RT-PCR revealed that the expression levels of p53, Bax and Beclin 1 were up-regulated in a dose-dependent manner, indicating that Beclin 1 was involved in Rapa induced autophagy and Rapa induced apoptosis as well as p53 up-regulation in PC-2 cells. The results demonstrated that Rapa could effectively inhibit proliferation and induce apoptosis and autophagy in PC-2 cells.

Autophagy upregulation promotes survival and attenuates doxorubicin-induced cardiotoxicity

This study evaluated whether the manipulation of autophagy could attenuate the cardiotoxic effects of doxorubicin (DXR) in vitro as well as in a tumour-bearing mouse model of acute doxorubicin-induced cardiotoxicity. We examined the effect of an increase or inhibition of autophagy in combination with DXR on apoptosis, reactive oxygen species (ROS) production and mitochondrial function. H9C2 rat cardiac myoblasts were pre-treated with bafilomycin A1 (autophagy inhibitor, 10 nM) or rapamycin (autophagy inducer, 50 μM) followed by DXR treatment (3 μM). The augmentation of autophagy with rapamycin in the presence of DXR substantially ameliorated the detrimental effects induced by DXR. This combination treatment demonstrated improved cell viability, decreased apoptosis and ROS production and enhanced mitochondrial function. To corroborate these findings, GFP-LC3 mice were inoculated with a mouse breast cancer cell line (EO771). Following the appearance of tumours, animals were either treated with one injection of rapamycin (4 mg/kg) followed by two injections of DXR (10 mg/kg). Mice were then sacrificed and their hearts rapidly excised and utilized for biochemical and histological analyses. The combination treatment, rather than the combinants alone, conferred a cardioprotective effect. These hearts expressed down-regulation of the pro-apoptotic protein caspase-3 and cardiomyocyte cross-sectional area was preserved. These results strongly indicate that the co-treatment strategy with rapamycin can attenuate the cardiotoxic effects of DXR in a tumour-bearing mouse model.

Rapamycin induces autophagy in the melanoma cell line M14 via regulation of the expression levels of Bcl-2 and Bax

Cancer therapy with rapamycin has been successfully implemented for kidney cancer, glioblastoma and prostate cancer. However, there are few studies concerning the effects of rapamycin on the treatment of human melanoma. In this study, we investigated whether rapamycin may be a promising strategy for the effective treatment of melanoma and explored the possible mechanism for this by culturing M14 cells in vitro and treating with rapamycin at three concentrations (10, 50 or 100 nmol/l). MDC and LC3B staining, western blot analysis, flow cytometry and transmission electron microscopy were employed. We revealed that rapamycin induced autophagy and inhibited the proliferation of M14 cells in a concentration-dependent manner, Furthermore, western blot analysis revealed an upregulated expression of Bcl-2 and downregulated expression of Bax in M14 cells. In conclusion, rapamycin induced autophagy and inhibited the growth of M14 cells. The mechanism may involve regulation of the expression of Bcl-2 family proteins. Rapamycin appears to be a promising strategy for the effective treatment of melanoma.

Rapamycin partially mimics the anticancer effects of calorie restriction in a murine model of pancreatic cancer

Etiologic factors for pancreatic cancer, the 4th deadliest malignant neoplasm in the United States, include obesity and abnormal glucose metabolism. Calorie restriction (CR) and rapamycin each affect energy metabolism and cell survival pathways via inhibition of mammalian target of rapamycin (mTOR) signaling. By using a Panc02 murine pancreatic cancer cell transplant model in 45 male C57BL/6 mice, we tested the hypothesis that rapamycin mimics the effects of CR on pancreatic tumor growth. A chronic regimen of CR, relative to an ad libitum-fed control diet, produced global metabolic effects such as reduced body weight (20.6 ± 1.6 g vs. 29.3 ± 2.3 g; P < 0.0001), improved glucose responsiveness, and decreased circulating levels of insulin-like growth factor (IGF)-1 (126 ± 8 ng/mL vs. 199 ± 11 ng/mL; P = 0.0006) and leptin (1.14 ± 0.2 ng/mL vs. 5.05 ± 1.2 ng/mL; P = 0.01). In contrast, rapamycin treatment (2.5 mg/kg intraperitoneal every other day, initiated in mice following 20 weeks of ad libitum control diet consumption), relative to control diet, produced no significant change in body weight, IGF-1 or leptin levels, but decreased glucose responsiveness. Pancreatic tumor volume was significantly reduced in the CR group (221 ± 107 mm(3); P < 0.001) and, to a lesser extent, the rapamycin group (374 ± 206 mm(3); P = 0.04) relative to controls (550 ± 147 mm(3)), and this differential inhibition correlated with expression of the proliferation marker Ki-67. Both CR and rapamycin decreased phosphorylation of mTOR, p70/S6K, and S6 ribosomal protein, but only CR decreased phosphorylation of Akt, GSK-3β, extracellular signal regulated kinase/mitogen-activated protein kinase, and STAT3(TYR705). These findings suggest that rapamycin partially mimics the anticancer effects of CR on tumor growth in a murine model of pancreatic cancer.

Development of molecularly targeted therapies in biliary tract cancers: reassessing the challenges and opportunities

Biliary tract cancers (BTCs), which encompass intra- and extrahepatic cholangiocarcinomas as well as gallbladder carcinomas, are a genetically diverse collection of cancers. Most patients with BTC will present with unresectable or metastatic disease. Although the standard systemic chemotherapy approaches are emerging, the prognosis remains poor. Development of molecularly targeted therapies in advanced BTC remains challenging. Recent early-stage clinical trials with targeted therapies appear promising, although the relationships between subsets of patients with positive responses to therapy and tumor genetics remain unexplored. Here we summarize the relevant molecular pathogenesis, recent and ongoing clinical trials with targeted agents, and the key issues in clinical trial design in BTC.

Leukemias induced by altered TRK-signaling are sensitive to mTOR inhibitors in preclinical models

Rapamycin is a potent allosteric mTORC1 inhibitor with clinical applications as an anticancer agent. However, only a fraction of cancer patients responds to the drug, and no biomarkers are available to predict tumor sensitivity. Recently, we and others have obtained evidence for potential involvement of tropomyosin-related kinase (TRK) receptor protein tyrosine kinases (TRKA, TRKB, TRKC) in leukemia. In the present study, we tested the therapeutic effect of Rapamycin and its analog RAD001 on altered TRK-induced leukemia in a murine model. Daily treatment with Rapamycin (2 mg/kg) or RAD001 (1 mg/kg) significantly prolonged the survival of treated animals (n = 40) compared with the placebo group. Consistently, both mTOR and S6 proteins were strongly dephosphorylated in vitro and in vivo after treatment with Rapamycin or RAD001. However, Rapamycin did not completely inhibit mTORC1-dependent phosphorylation of 4E-BP1. With exception of one mouse showing slight reactivation of Akt after treatment, no reactivation of MAPK or Akt pathways was observed in other resistant tumors. Interestingly, leukemic cells isolated from a Rapamycin-resistant mouse were still highly sensitive to Rapamycin in vitro. Our findings suggest that altered TRK signaling may be a good predictor of tumor sensitivity to mTOR inhibition and that pathways other than MAPK and Akt exist that may trigger resistance of leukemic cells to Rapamycin in vivo.

Genetics of biliary tract cancers and emerging targeted therapies

Biliary tract cancers (BTC), which encompass intra- and extrahepatic cholangiocarcinomas and gallbladder carcinomas, are a genetically diverse collection of cancers. Evidence suggests distinct models of molecular and pathologic progression, and a growing body of genetics data points to a heterogeneous collection of underlying mutations in key oncogenes and tumor suppressor genes. Although tumor genetics have been used to tailor individual treatment regimens and guide clinical decision making in other cancers, these principles have not been applied in BTC. Recent clinical trials with targeted therapies seem promising, although the relationships between subsets of patients with positive responses to therapy and tumor genetics remain unexplored. Here, we summarize the molecular pathogenesis and genetics of BTCs and animal modeling and relate these to recent and ongoing clinical trials with targeted agents.

Expression of phospho-ERK1/2 and PI3-K in benign and malignant gallbladder lesions and its clinical and pathological correlations

Background

An increasing number of studies have shown that ERK and PI3-K/AKT signaling pathways are involved in various human cancers including hepatocellular carcinoma and cholangiocarcinoma. However, few studies have examined gallbladder cancer specimens, and little is known about the clinical and pathological significance of ERK1/2 and PI3-K/AKT signaling changes in gallbladder adenocarcinoma. In this study, we examined phospho-ERK1/2 (p-ERK1/2) and PI3K expression and analyzed its clinicopathological impact in gallbladder adenocarcinoma.

Methods

Immunohistochemistry was used to detect and compare the frequency of p-ERK1/2 and PI3-K expression in gallbladder adenocarcinoma, peri-tumor tissues, adenomatous polyps, and chronic cholecystitis specimens.

Results

The positive staining for p-EKR1/2 and PI3-K were 63/108 (58.3%) and 55/108 (50.9%) in gallbladder adenocarcinoma; 14/46 (30.4%) and 5/46 (10.1%) in peri-tumor tissues; 3/15 (20%) and 3/15 (20%) in adenomatous polyps; and 4/35 (11.4%) and 3/35 (8.6%) in chronic cholecystitis. The positive rate of p-ERK1/2 or PI3-K in gallbladder adenocarcinoma was significantly higher than that in peri-tumor tissue (both, P < 0.01), adenomatous polyps (p-ERK1/2, P < 0.01; PI3-K, P < 0.05), and chronic cholecystitis (both, P < 0.01). The positive staining for p-ERK1/2 or PI3-K was significantly lower in well/highly-differentiated adenocancinomas with maximal diameter < 2.0 cm, no metastasis to lymph node, and no infiltration of regional tissues or organs compared to poorly-differentiated adenocarcinomas which are characterized by a maximal diameter ≥ 2.0 cm, with metastasis to lymph node and infiltration of regional tissues or organs (P < 0.05 or P < 0.01). Moreover, the frequency of p-ERK1/2 expression in gallbladder adenocarcinomas without gallstone was significantly lower than those with gallstones. Increased expression of p-ERK1/2 (P < 0.05) and PI3K (P = 0.062) was associated with decreased overall survival. Multivariate Cox regression analysis showed that increased p-ERK1/2 expression was an independent prognostic predictor in gallbladder carcinoma (P = 0.028).

Conclusion

Increased expression of p-ERK1/2 and PI3K might contribute to gallbladder carcinogenesis. p-ERK1/2 over-expression is correlated with decreased survival and therefore may serve as an important biological marker in development of gallbladder adenocarcinoma.

Expression and clinical significance of mTOR/P70S6K signaling pathway in hepatocellular carcinoma

AIM: To investigate expression of mTOR/P70S6K signaling pathway in human hepatocellualr carcinoma (HCC) and to discuss its role in the hepatocellular carcinogenesis.

METHODS: Reverse transcription polymerase chain reactions (RT-PCR) was employed to determine the mRNA expression of mTOR/P70S6K signaling pathway in cancerous and paracancerous tissuess of 20 HCC cases and normal healthy liver tissues of 10 cases. The relationship between expression of the genes mRNA in HCC tissues and related clinical parameters was analyzed.

RESULTS: The expression level of mTOR/P70S6K signaling pathway was markedly higher in the HCC tissues than in the paracancerous tissues or normal healthy liver tissues (mTOR mRNA: 0.594 ± 0.218 vs 0.437 ± 0.156, 0.594 ± 0.218 vs 0.383 ± 0.081, both P < 0.05; P70S6K mRNA: 0.610 ± 0.147 vs 0.486 ± 0.162, 0.610 ± 0.147 vs 0.440 ± 0.141, both P < 0.05). There was a positive correlation between mTOR mRNA and P70S6K mRNA expression in HCC tissues (r = 0.548, P = 0.012). There was also a positive correlation between mTOR mRNA and P70S6K mRNA expressions in paracancerous tissues and the normal liver tissues (r = 0.607, 0.737, P = 0.005, 0.015). The expression of mTOR/P70S6K signaling pathway in the HCC tissues was significantly correlated with the pathological grading, the pylic cancer embolus, but not with the diameter, level of the serous alpha - fetoprotein (AFP), and gender.

CONCLUSION: The mTOR/P70S6K signaling pathway is specifically activated in HCC tissues. The mTOR/P70S6K signaling pathway might play an important role in the pathogenesis of HCC.

Evaluation of the mammalian target of rapamycin pathway and the effect of rapamycin on target expression and cellular proliferation in osteosarcoma cells from dogs

OBJECTIVE

To investigate activation of the mammalian target of rapamycin (mTOR) pathway and the antitumor effect of rapamycin in canine osteosarcoma cells.

SAMPLE POPULATION

3 established primary canine osteosarcoma cell lines generated from naturally developing tumors.

PROCEDURES

Expression of total and phosphorylated mTOR and p70S6 kinase was assessed by use of western blot analysis in canine osteosarcoma cells with and without the addition of rapamycin. A clonogenic assay was performed to determine the surviving fraction of osteosarcoma cells at various concentrations of rapamycin.

RESULTS

Total and phosphorylated mTOR and p70S6 kinase expression was evident in all 3 cell lines evaluated, which was indicative of activation of this pathway. Treatment with rapamycin resulted in a time-dependent decrease in phosphorylated mTOR expression and a lack of detectable phosphorylated p70S6 kinase. No detectable change in expression of total mTOR and total p70S6 kinase was identified after rapamycin treatment. The clonogenic assay revealed a significant dose-dependent decrease in the surviving fraction for all 3 cell lines when treated with rapamycin.

CONCLUSIONS AND CLINICAL RELEVANCE

These data indicated that mTOR and its downstream product are present and active in canine osteosarcoma cells. The pathway can be inhibited by rapamycin, and treatment of cells with rapamycin decreased the surviving tumor cell fraction. These data support the molecular basis for further investigation into the use of mTOR inhibitors as an antineoplastic approach for dogs with osteosarcoma.

Serial analysis of gene expression identifies connective tissue growth factor expression as a prognostic biomarker in gallbladder cancer

BACKGROUND

Gallbladder cancer (GBC) is an uncommon neoplasm in the United States, but one with high mortality rates. This malignancy remains largely understudied at the molecular level such that few targeted therapies or predictive biomarkers exist.

EXPERIMENTAL DESIGN

We built the first series of serial analysis of gene expression (SAGE) libraries from GBC and nonneoplastic gallbladder mucosa, composed of 21-bp long-SAGE tags. SAGE libraries were generated from three stage-matched GBC patients (representing Hispanic/Latino, Native American, and Caucasian ethnicities, respectively) and one histologically alithiasic gallbladder. Real-time quantitative PCR was done on microdissected epithelium from five matched GBC and corresponding nonneoplastic gallbladder mucosa. Immunohistochemical analysis was done on a panel of 182 archival GBC in high-throughput tissue microarray format.

RESULTS

SAGE tags corresponding to connective tissue growth factor (CTGF) transcripts were identified as differentially overexpressed in all pairwise comparisons of GBC (P < 0.001). Real-time quantitative PCR confirmed significant overexpression of CTGF transcripts in microdissected primary GBC (P < 0.05), but not in metastatic GBC, compared with nonneoplastic gallbladder epithelium. By immunohistochemistry, 66 of 182 (36%) GBC had high CTGF antigen labeling, which was significantly associated with better survival on univariate analysis (P = 0.0069, log-rank test).

CONCLUSIONS

An unbiased analysis of the GBC transcriptome by SAGE has identified CTGF expression as a predictive biomarker of favorable prognosis in this malignancy. The SAGE libraries from GBC and nonneoplastic gallbladder mucosa are publicly available at the Cancer Genome Anatomy Project web site and should facilitate much needed research into this lethal neoplasm.

Targeted therapies for cancer of the gallbladder

PURPOSE OF REVIEW

Adenocarcinomas of the gallbladder are uncommon, aggressive tumors with poor survival. This review summarizes advances in understanding the biology of gallbladder cancer.

RECENT FINDINGS

Published response rates of adenocarcinomas of the gallbladder to chemotherapy are less than 30% and no survival benefit has been demonstrated from palliative systemic therapy. New information on the molecular carcinogenic mechanisms of these malignancies, combined with findings from animal models, may lead to improved treatment for patients.

SUMMARY

Improved understanding of the molecular carcinogenesis of adenocarcinomas of the gallbladder, coupled with the availability of novel molecularly 'targeted' chemotherapeutic agents, may improve outcome for patients.

Role of mTOR in solid tumor systems: a therapeutical target against primary tumor growth, metastases, and angiogenesis

The mammalian target of rapamycin (mTOR) is a controller of cell growth with multiple effects on cancer development and progression. Being closely linked to key oncogenic pathways that regulate tumor cell growth and cell cycle progression, mTOR integrates the cellular response to mitogenic and growth stimuli. Rapamycin and its analogs temsirolimus and everolimus are specific inhibitors of mTOR that exert suppressive effects on proliferation, invasion, and metastasis and induce apoptosis of tumor cells. Apart from the direct effects of mTOR inhibitors on tumor cells, rapamycin and its analogs have potent antiangiogenic properties related to the suppression of vascular endothelial growth factor signal transduction. While the use of mTOR inhibitors as a monotherapy seems to be insufficient to effectively control tumor progression in most tumor entities, combination with tyrosine kinase inhibitors or cytotoxic agents might potentiate the antitumoral effects of mTOR inhibition. In a clinical setting, mTOR inhibitors show an acceptable safety profile over a wide dose range. Currently, mTOR inhibitors are tested in multiple trials in combination with other agents in various cancer entities in intermittent schedules to avoid immunosuppression. However, lacking adequate surrogate and response parameters, the most effective biological dosing schedules remain to be defined. Considering these apparent limitations, the full clinical potential of this promising class of drugs is at risk to be missed by applying them inadequately.