Aberrant activation of the mTOR pathway and anti-tumour effect of everolimus on oesophageal squamous cell carcinoma. Br J Cancer. 2012;106:876-882. [PMID: 22333597 PMCID: PMC3305959 DOI: 10.1038/bjc.2012.36]

Therapeutic implications of signaling pathways and tumor microenvironment interactions in esophageal cancer

Esophageal cancer (EC) is significantly influenced by the tumor microenvironment (TME) and altered signaling pathways. Downregulating these pathways in EC is essential for suppressing tumor development, preventing metastasis, and enhancing therapeutic outcomes. This approach can increase tumor sensitivity to treatments, enhance patient outcomes, and inhibit cancer cell proliferation and spread. The TME, comprising cellular and non-cellular elements surrounding the tumor, significantly influences EC's development, course, and treatment responsiveness. Understanding the complex relationships within the TME is crucial for developing successful EC treatments. Immunotherapy is a vital TME treatment for EC. However, the heterogeneity within the TME limits the application of anticancer drugs outside clinical settings. Therefore, identifying reliable microenvironmental biomarkers that can detect therapeutic responses before initiating therapy is crucial. Combining approaches focusing on EC signaling pathways with TME can enhance treatment outcomes. This integrated strategy aims to interfere with essential signaling pathways promoting cancer spread while disrupting factors encouraging tumor development. Unraveling aberrant signaling pathways and TME components can lead to more focused and efficient treatment approaches, identifying specific cellular targets for treatments. Targeting the TME and signaling pathways may reduce metastasis risk by interfering with mechanisms facilitating cancer cell invasion and dissemination. In conclusion, this integrative strategy has significant potential for improving patient outcomes and advancing EC research and therapy. This review discusses the altered signaling pathways and TME in EC, focusing on potential future therapeutics.

A Comprehensive Review on Targeted Cancer Therapy: New Face of Treatment Approach

Cancer is one of life's most difficult difficulties and a severe health risk everywhere. Except for haematological malignancies, it is characterized by unchecked cell growth and a lack of cell death, which results in an aberrant tissue mass or tumour. Vascularization promotes tumor growth, which eventually aids metastasis and migration to other parts of the body, ultimately resulting in death. The genetic material of the cells is harmed or mutated by environmental or inherited influences, which results in cancer. Presently, anti-neoplastic medications (chemotherapy, hormone, and biological therapies) are the treatment of choice for metastatic cancers, whilst surgery and radiotherapy are the mainstays for local and non-metastatic tumors. Regrettably, chemotherapy disturbs healthy cells with rapid proliferation, such as those in the gastrointestinal tract and hair follicles, leading to the typical side effects of chemotherapy. Finding new, efficient, targeted therapies based on modifications in the molecular biology of tumor cells is essential because current chemotherapeutic medications are harmful and can cause the development of multidrug resistance. These new targeted therapies, which are gaining popularity as demonstrated by the FDA-approved targeted cancer drugs in recent years, enter molecules directly into tumor cells, diminishing the adverse reactions. A form of cancer treatment known as targeted therapy goes after the proteins that regulate how cancer cells proliferate, divide, and disseminate. Most patients with specific cancers, such as chronic myelogenous leukemia (commonly known as CML), will have a target for a particular medicine, allowing them to be treated with that drug. Nonetheless, the tumor must typically be examined to determine whether it includes drug targets.

Alpha Protein Kinase 2 Promotes Esophageal Cancer via Integrin Alpha 11

Background

As a common disease around the world, esophageal cancer (EC) primarily includes two subclasses: esophageal adenocarcinoma and esophageal squamous cell carcinoma. Mortality has been rising over the years; hence, exploring the mechanism of EC development has become critical. Among the alpha protein kinases, alpha protein kinase 2 (ALPK2) presumably has a connection with EC, but it has never been revealed before.

Methods

In this study, IHC analysis was used for ALPK2 expression quantification in ES tissues. TE-1 and Eca-109, which are both human EC cell lines, were used for in vitro analysis of cell proliferation, migration, apoptosis, and colony formation.

Results

ALPK2 was found to have an abundant expression within EC tissues (P < 0.001), as well as in the two selected human EC cell lines (P < 0.05). The data showed that ALPK2 depletion suppressed EC cell proliferation, migration, and colony formation, meanwhile stimulating apoptosis (P < 0.001). The in vivo experiments also displayed inhibitory effects caused by ALPK2 depletion on EC tumorigenesis (P < 0.001). It was further validated that ALPK2 depletion made the phosphorylation of Akt and mTOR, as well as CDK6 and PIK3CA levels downregulated (P < 0.001). Mechanistically, we identified integrin alpha 11 (ITGA11) as a downstream gene of ALPK2 regulating EC. More importantly, we found that ITGA11 elevation promoted cell proliferation and migration and rescued the suppression effects caused by ALPK2 depletion (P < 0.001).

Conclusions

ALPK2 promotes esophageal cancer via integrin its downstream gene alpha 11; ALPK2 can potentially act as a target for the treatment of EC.

PI3K/Akt/mTOR Signaling Pathway: Role in Esophageal Squamous Cell Carcinoma, Regulatory Mechanisms and Opportunities for Targeted Therapy

Esophageal squamous cell carcinoma (ESCC), is the most common type of esophageal cancer worldwide, mainly occurring in the Asian esophageal cancer belt, including northern China, Iran, and parts of Africa. Phosphatidlinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway is one of the most important cellular signaling pathways, which plays a crucial role in the regulation of cell growth, differentiation, migration, metabolism and proliferation. In addition, mutations in some molecules of PI3K/Akt/mTOR pathway are closely associated with survival and prognosis in ESCC patients. A large number of studies have found that there are many molecules in ESCC that can regulate the PI3K/Akt/mTOR pathway. Overexpression of these molecules often causes aberrant activation of PI3K/Akt/mTOR pathway. Currently, several effective PI3K/Akt/mTOR pathway inhibitors have been developed, which can play anticancer roles either alone or in combination with other inhibitors. This review mainly introduces the general situation of ESCC, the composition and function of PI3K/Akt/mTOR pathway, and regulatory factors that interact with PI3K/Akt/mTOR signaling pathway. Meanwhile, mutations and inhibitors of PI3K/Akt/mTOR pathway in ESCC are also elucidated.

N7-methylguanosine tRNA modification promotes esophageal squamous cell carcinoma tumorigenesis via the RPTOR/ULK1/autophagy axis

Mis-regulated RNA modifications promote the processing and translation of oncogenic mRNAs to facilitate cancer progression, while the molecular mechanisms remain unclear. Here we reveal that tRNA m⁷G methyltransferase complex proteins METTL1 and WDR4 are significantly up-regulated in esophageal squamous cell carcinoma (ESCC) tissues and associated with poor ESCC prognosis. In addition, METTL1 and WDR4 promote ESCC progression via the tRNA m⁷G methyltransferase activity in vitro and in vivo. Mechanistically, METTL1 or WDR4 knockdown leads to decreased expression of m⁷G-modified tRNAs and reduces the translation of a subset of oncogenic transcripts enriched in RPTOR/ULK1/autophagy pathway. Furthermore, ESCC models using Mettl1 conditional knockout and knockin mice uncover the essential function of METTL1 in promoting ESCC tumorigenesis in vivo. Our study demonstrates the important oncogenic function of mis-regulated tRNA m⁷G modification in ESCC, and suggest that targeting METTL1 and its downstream signaling axis could be a promising therapeutic target for ESCC treatment.

Deregulation of METTL1-mediated N7- methylguanosine tRNA modification can promote oncogenesis. Here, the authors report that this modification regulates the translation of proteins in both the mTOR and negative regulators of autophagy pathways, resulting in the progression of esophageal squamous cell carcinoma.

Rapamycin suppresses the PI3K/AKT/mTOR signaling pathway by targeting SIRT1 in esophageal cancer

Rapamycin, a secondary metabolite produced by Streptomyces hygroscopicus, is known for its pharmacological effects, especially antitumor and immunosuppressive activities. However, the antitumoral effects of rapamycin in human esophageal cancer (EC) are still poorly understood. To investigate the potential of rapamycin in EC treatment, sirtuin 1 (SIRT1) mRNA expression was quantified in the tissue of patients with EC or in EC cell lines using reverse transcription-quantitative PCR. The protein levels of SIRT1 and PI3K/AKT/mTOR were measured via western blotting. Furthermore, cell viability, migration and invasion were investigated by Cell Counting Kit-8, wound healing and Transwell assays, respectively. The present results suggested that SIRT1 expression was upregulated in EC. In vitro, the inhibitory effect of rapamycin on cell viability in EC was strengthened or weakened after small interfering (si)-SIRT1 or pcDNA3.1/SIRT1 transfection. Furthermore, SIRT1 rescued the inhibitory effect of rapamycin on the migration and invasion of EC cells. In vivo, si-SIRT1 or SIRT1 overexpression in mice could enhance or rescue the inhibitory effects of rapamycin on tumor growth. In addition, SIRT1 transfection rescued the decreased level of phosphorylated (p)-PI3K, p-AKT and p-mTOR induced by rapamycin treatment. Taken together, the present results suggested that rapamycin suppressed the cell viability, migration, invasion and PI3K/AKT/mTOR signaling pathway in EC by negatively regulating SIRT1.

Harmaline isolated from Peganum harmala suppresses growth of esophageal squamous cell carcinoma through targeting mTOR

Harmaline is a naturally occurring β-carboline alkaloid that is isolated from Peganum harmala. It has shown efficacy in treating Parkinson's disease and has been reported to exhibit antimicrobial and anticancer properties. However, the molecular mechanism of harmaline in the context of esophageal squamous cell carcinoma (ESCC) has not been characterized. Here, we report that harmaline attenuates ESCC growth by directly targeting the mammalian target of rapamycin (mTOR). Harmaline strongly reduced cell proliferation and anchorage-independent cell growth. Additionally, harmaline treatment induced G2/M phase cell-cycle arrest through upregulation of p27. The results of in vitro and cell-based assays showed that harmaline directly inhibited the activity of mTOR kinase and the phosphorylation of its downstream pathway components. Depletion of mTOR using an shRNA-mediated strategy in ESCC cell lines indicated that reduced mTOR protein expression levels are correlated with decreased cell proliferation. Additionally, we observed that the inhibitory effect of harmaline was dependent upon mTOR expression. Notably, oral administration of harmaline suppressed ESCC patient-derived tumor growth in vivo. Taken together, harmaline is a potential mTOR inhibitor that might be used for therapeutically treating ESCC.

Cordycepin enhances the chemosensitivity of esophageal cancer cells to cisplatin by inducing the activation of AMPK and suppressing the AKT signaling pathway

Although cisplatin (cDDP), is a first-line chemotherapy drug for esophageal cancer, it still has the potential to develop drug resistance and side effects. There is increasing evidence that cordycepin can work synergistically with other chemotherapy drugs. Therefore, we investigated whether combination therapy of cordycepin and cDDP may enhance the therapeutic effect of cDDP. We performed a series of functional tests to study the effect of medical treatment on esophageal cancer cells. We then used GO analysis to examine the pathways affected by treatment with cordycepin and cDDP. Next, we observed changes in the abundance of the selected pathway proteins. The in vivo animal model supported the results of the in vitro experiments. Co-treatment with cordycepin and cDDP inhibited cell growth, migration, and metastasis, as well as induced apoptosis. Cordycepin was found to effectively enhance activation of AMPK and inhibited activity of AKT. In all treatment groups, the expression levels of p-PI3K, p-Akt, p-p70S6K, Caspase-3, and Bcl-2 were significantly reduced, while the expression levels of p-AMPK, cleaved Caspase-3, and Bax increased, and the total levels of Akt, PI3K, and p70S6K levels remained unchanged. Overall, cordycepin was found to enhance the chemical sensitivity of esophageal cancer cells to cisplatin by inducing AMPK activation and inhibiting the AKT signaling pathway. Combination therapy of cordycepin and cisplatin represent a novel potential treatment of esophageal cancer.

Advances in targeted therapy for esophageal cancer

Esophageal cancer (EC) is one of the most lethal cancers in the world, and its morbidity and mortality rates rank among the top ten in China. Currently, surgical resection, radiotherapy and chemotherapy are the primary clinical treatments for esophageal cancer. However, outcomes are still unsatisfactory due to the limited efficacy and severe adverse effects of conventional treatments. As a new type of approach, targeted therapies have been confirmed to play an important role in the treatment of esophageal cancer; these include cetuximab and bevacizumab, which target epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF), respectively. In addition, other drugs targeting surface antigens and signaling pathways or acting on immune checkpoints have been continuously developed. For example, trastuzumab, a monoclonal antibody targeting human epidermal growth factor receptor 2 (HER-2), has been approved by the Food and Drug Administration (FDA) as a first-line treatment of HER-2-positive cancer. Moreover, the PD-L1 inhibitor pembrolizumab has been approved as a highly efficient drug for patients with PD-L1-positive or advanced esophageal squamous cell carcinoma (ESCC). These novel drugs can be used alone or in combination with other treatment strategies to further improve the treatment efficacy and prognosis of cancer patients. Nevertheless, adverse events, optimal dosages and effective combinations still need further investigation. In this review, we expound an outline of the latest advances in targeted therapies of esophageal cancer and the mechanisms of relevant drugs, discuss their efficacy and safety, and provide a clinical rationale for precision medicine in esophageal cancer.

The Esophageal Cancer and the PI3K/AKT/mTOR Signaling Regulatory microRNAs: a Novel Marker for Prognosis, and a Possible Target for Immunotherapy

The Phosphatidylinositol 3-kinase/AKT/Mammalian Target of Rapamycin (PI3K/AKT/mTOR) pathway has a critical regulatory role in cell biology including translation, transcription, and autophagy. Dysregulation of this pathway is involved in the pathogenesis, development, and prognosis of esophageal cancer that has been assessed in the recent years and its potential as a target in therapy. This report summarizes the current knowledge about PI3K/AKT/mTOR pathway and its cross-talk with a focus on the value of targeting this pathway as a potential therapeutic target in the treatment of esophageal cancer.

Everolimus inhibits the proliferation and migration of epidermal growth factor receptor-resistant lung cancer cells A549 via regulating the microRNA-4328/phosphatase and tensin homolog signaling pathway

Lung cancer is the most common cancer type worldwide, and investigating novel therapeutics methods for the treatment of chemoresistant lung cancer are of notable clinical significance. Reverse transcription-quantitative polymerase chain reaction and western blotting assays were performed to analyze the expression levels of phosphatase and tensin homolog (PTEN) and microRNA-4328 (miR-4328), and Cell Counting Kit-8 (CCK-8) and Transwell migration assays were conducted to evaluate the proliferation and migration of A549 cells, respectively. Everolimus was observed to upregulate the expression of PTEN and inhibit the proliferation and migration of A549 cells in a dose-dependent manner. The knockdown of PTEN abolished the effects of everolimus on the proliferation and migration of A549 cells, and everolimus was demonstrated to upregulate PTEN, and inhibit the proliferation and migration of A549 cells via downregulating miR-4328. Collectively, the results of the present study indicate that everolimus inhibited the proliferation and migration of EGFR-resistant A549 lung cancer cells via regulating the miR-4328/PTEN signaling pathway.

microRNA-10b confers cisplatin resistance by activating AKT/mTOR/P70S6K signaling via targeting PPARγ in esophageal cancer

It is well known that the acquisition of chemoresistance is a major obstacle for the effective treatment of human cancers. It is reported that microRNAs (miRNAs) are implicated in chemotherapy resistance of various malignancies. miR-10b was previously proved as an oncogene in multiple malignancies, including esophageal cancer. However, its biological significance in regulating cisplatin (DDP) resistance in esophageal cancer is still elusive. Here, we observed that miR-10b expression was upregulated and peroxisome proliferator-activated receptor-γ (PPARγ) expression was downregulated in esophageal cancer tumor tissues and cells. PPARγ was proved as a functional target of miR-10b. Moreover, suppression of miR-10b enhanced the chemosensitivity of esophageal cancer cells to DDP in vitro and in vivo. In addition, PPARγ-mediated DDP sensitivity was weakened by miR-10b overexpression. Furthermore, miR-10b-activated AKT/mTOR/p70S6K signaling pathway through targeting PPARγ. Inactivation of AKT/mTOR/p70S6K by AKT inhibitor (GSK690693) attenuated miR-10b-induced DDP resistance in esophageal cancer cells. Taken together these observation, miRNA-10b-mediated PPARγ inhibition enhanced DDP resistance by activating the AKT/mTOR/P70S6K signaling in esophageal cancer, suggesting a potential target to improve therapeutic response of patients with esophageal cancer to DDP.

Histone deacetylases inhibitor MS-275 suppresses human esophageal squamous cell carcinoma cell growth and progression via the PI3K/Akt/mTOR pathway

Esophageal squamous cell carcinoma (ESCC) is a malignant tumor with low survival rate, so new therapies are urgently needed. Histone deacetylases (HDACs) play a critical role in tumorigenesis, and HDACs inhibition is a potential therapeutic target in ESSC. In our study, we evaluated the effect and molecular mechanism of MS-275 (an inhibitor of HDACs) on ESCC cells. We found that HDAC1 and HDAC2 were overexpressed in ESCC tissues and related with clinical pathological features of patients with ESCC. MS-275 markedly reduced HDAC1 and HDAC2 expression, whereas increased the level of AcH3 and AcH2B. MS-275 suppressed proliferation and clonogenicity of ESCC cells in a concentration-dependent manner. In addition, MS-275 induced apoptosis, arrested cell cycle, and inhibited migration, epithelial-mesenchymal transition, and sphere-forming ability of ESCC cells in vitro. Moreover, p-Akt1 and p-mTOR were downregulated by MS-275. Finally, MS-275 significantly inhibited tumor growth in vivo. Taken together, HDAC1 and HDAC2 are associated with the progression of ESCC, and MS-275 hinders the progression and stemness of ESCC cells by suppressing the PI3K/Akt/mTOR pathway. Our findings show that MS-275 inhibits ESCC cells growth in vitro and in vivo, which is a potential drug for the ESCC therapy.

The combination of everolimus and terameprocol exerts synergistic antiproliferative effects in endometrial cancer: molecular role of insulin-like growth factor binding protein 2

Oncogenic PIK3CA mutations are common in endometrial cancers, and the PI3K/AKT/mTOR pathway is targetable by drugs. We sought to investigate whether the combination of an mTOR inhibitor, everolimus (RAD001), and an AKT inhibitor, terameprocol (M4N), exerts better antiproliferative effects in endometrial cancer. The molecular mechanisms underlying their pharmacological action were also examined. The combination of RAD001 and M4N exerted in vitro synergistic effects on cell viability, apoptosis, and expression of IGFBP2 in endometrial cancer cells. Mechanistically, the Sp1 site on the IGFBP2 promoter was required for RAD001- and M4N-induced downregulation. IGFBP2 protein expression was higher in endometrial cancer than in the normal endometrium (P < 0.001). Furthermore, elevated IGFBP2 histoscores were significantly associated with a lower overall survival (P = 0.021). In conclusion, our in vitro results demonstrate that RAD001 and M4N exert synergistic antiproliferative effects against endometrial cancer cells, which appeared to be mediated by the inhibition of IGFBP2, a key anti-apoptotic regulator. Further clinical studies of this drug combination in patients with endometrial cancer may be warranted, especially in the presence of PIK3CA and IGFBP2 aberrations. KEY MESSAGES: RAD001 and M4N synergistically suppress endometrial cancer growth. IGFBP2 is overexpressed in endometrial cancer. The combination of RAD001 and M4N significantly reduces IGFBP2 overexpression. Sp1 binding site on the IGFBP2 promoter is required for RAD001- and M4N-induced downregulation. High IGFBP2 histoscore in endometrial cancer portends a poor prognosis.

CASTOR1 suppresses the progression of lung adenocarcinoma and predicts poor prognosis

As a naturally occurring inhibitor of mammalian target of rapamycin (mTOR), accumulated evidence has confirmed that CASTOR1 plays a pivotal role in regulating the progression of human malignancies. However, the function of CASTOR1 in the development of lung adenocarcinoma is still unclear. Here we report that the expression of CASTOR1 is significantly reduced in lung adenocarcinoma cell lines as compared with that in normal lung epithelial cells. Cellular studies further revealed that ectopic CASTOR1 expression led to a significant suppression of the cellular proliferation, migration, and invasion of PC-9 cells. To further test the role of CASTOR1 in human patients with lung cancers, tumor tissues derived from lung cancer patients and paired adjacent normal lung tissues were collected for immunohistochemical​​​​​​, biochemical, and molecular biology analysis. Immunoblotting and real-time quantitative reverse transcription polymerase chain reaction analysis is revealed that CASTOR1 was significantly reduced in tumor tissues as compared with that in paired normal lung tissues. With immunostaining and retrospective analysis of pathological samples from lung cancer patients further revealed that expression of CASTOR1 was negatively correlated with smoking history, TNM stage, lymphnode metastasis, and distant metastasis. Furthermore, Kaplan-Meier survival analysis indicated that patients with low CASTOR1 expression levels had a significantly worse 5-year survival rate than those with high CASTOR1 expression. To further explore the molecular actions of CASTOR1 in lung cancer development, biochemical assays were performed and the results suggested that ectopic CASTOR1 expression resulted significant suppression of mTOR and downstream S6K phosphorylation, indicating that CASTOR1 might regulate the progression of lung adenocarcinoma by controlling mTOR activation. Thus, these findings demonstrated that CASTOR1 inhibits the tumorigenesis of lung adenocarcinoma cells and might serve as a potential therapeutic target or prognostic marker for human patients with lung adenocarcinoma.

Angiotensin II type I receptor (AT1R) is an independent prognosticator of esophageal squamous cell carcinoma and promotes cells proliferation via mTOR activation

Background

The aim of this study was to investigate the effects of the angiotensin II/ angiotensin II type I receptor (AT1R) and angiotensin II type II receptor (AT2R) signaling pathway in esophageal squamous cell carcinoma (ESCC).

Methods

Immunohistochemistry was performed to evaluate the expression levels of AT1R and AT2R in tissues from 152 surgically resected ESCC patients, and those expression levels were then correlated with treatment outcomes. The angiotensin II/AT1R/AT2R signaling pathway and its biological effects in the context of ESCC were investigated in vitro and in vivo.

Results

In human samples, AT1R overexpression was univariately associated with inferior overall survival and remained multivariately independent (hazard ratio=1.812). In vitro, angiotensin II stimulated the growth of ESCC cells in a dose-dependent manner. Treatment with irbesartan or AT1R-RNAi knockdown but not treatment with PD123319 significantly decreased the level of angiotensin II-induced ESCC cell proliferation. Angiotensin II also caused mTOR activation in a dose-dependent manner, and everolimus or mTOR-RNAi knockdown significantly suppressed the level of angiotensin II-induced ESCC cell proliferation. Furthermore, AT1R-RNAi knockdown suppressed the activation of mTOR. Clinically, AT1R expression was also correlated with phosphorylated mTOR expression. In a xenograft model, local angiotensin II injection enhanced tumor growth, and this effect could be decreased by treatment with irbesartan or everolimus. In a 4-NQO-induced-ESCC murine model, irbesartan significantly decreased the incidence of esophageal tumor.

Conclusions

These findings suggest that AT1R overexpression is an independent adverse prognosticator for patients with ESCC and that angiotensin II/AT1R signaling stimulates ESCC growth, in part through mTOR activation.

Everolimus exhibits anti-tumorigenic activity in obesity-induced ovarian cancer

Everolimus inhibits mTOR kinase activity and its downstream targets by acting on mTORC1 and has anti-tumorigenic activity in ovarian cancer. Clinical and epidemiologic data find that obesity is associated with worse outcomes in ovarian cancer. In addition, obesity leads to hyperactivation of the mTOR pathway in epithelial tissues, suggesting that mTOR inhibitors may be a logical choice for treatment in obesity-driven cancers. However, it remains unclear if obesity impacts the effect of everolimus on tumor growth in ovarian cancer. The present study was aimed at evaluating the effects of everolimus on cytotoxicity, cell metabolism, apoptosis, cell cycle, cell stress and invasion in human ovarian cancer cells. A genetically engineered mouse model of serous ovarian cancer fed a high fat diet or low fat diet allowed further investigation into the inter-relationship between everolimus and obesity in vivo. Everolimus significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, reduced invasion and caused cellular stress via inhibition of mTOR pathways in vitro. Hypoglycemic conditions enhanced the sensitivity of cells to everolimus through the disruption of glycolysis. Moreover, everolimus was found to inhibit ovarian tumor growth in both obese and lean mice. This reduction coincided with a decrease in expression of Ki-67 and phosphorylated-S6, as well as an increase in cleaved caspase 3 and phosphorylated-AKT. Metabolite profiling revealed that everolimus was able to alter tumor metabolism through different metabolic pathways in the obese and lean mice. Our findings support that everolimus may be a promising therapeutic agent for obesity-driven ovarian cancers.

The Expression and Prognostic Impact of the PI3K/AKT/mTOR Signaling Pathway in Advanced Esophageal Squamous Cell Carcinoma

The abnormal phosphatase and tensin homolog expression and activated phosphoinositide-3 kinase/Protein kinase B (AKT)/mammalian target of rapamycin signaling pathway are involved in the progression of esophageal squamous cell carcinoma. By assessing the expression pattern of key components in the phosphoinositide-3 kinase/AKT/mammalian target of rapamycin signaling pathway by immunohistochemistry in tumor and nontumor esophageal mucosa from patients with esophageal squamous cell carcinomas, we aimed to carefully explore the relationship between the various protein expressions and clinicopathological factors, as well as patient outcome. A total of 145 tumor and 145 nontumor samples from patients with esophageal squamous cell carcinoma, collected from HuaShan Hospital (Shanghai, China) were evaluated. Clinical characteristics, the targeted protein expressions (including phosphatase and tensin homolog, phosphoinositide-3 kinase, AKT, p-AKT, mammalian target of rapamycin, p-mTOR, p70S6 kinase 1, p-P70S6K1, elongation initiation factor 4E binding protein-1, and p-4E-BP1, and survival rate were analyzed. Among them, phosphoinositide-3 kinase, AKT, p-AKT, mammalian target of rapamycin, p-mTOR, elongation initiation factor 4E binding protein-1, p70S6 kinase 1, and p-P70S6K1 proteins were significantly upregulated in tumor tissue. Conversely, phosphatase and tensin homolog was largely downregulated in tumor tissue, notably in pT3-T4 tumors. Low expression of phosphatase and tensin homolog whereas high expression of mammalian target of rapamycin signaling components in tumors was closely related to the presence of lymph node metastases and advanced TNM stage (all P < .05). Moreover phosphatase and tensin homolog, mammalian target of rapamycin, and p70S6 kinase 1 were correlated with overall survival as well as p-mTOR was correlated with progression-free survival (all P < .05). Overexpression of mammalian target of rapamycin was proved to be an independent adverse prognostic factor for overall survival in esophageal squamous cell carcinomas. Our results suggest that the phosphoinositide-3 kinase/AKT/mammalian target of rapamycin signaling pathway is activated in esophageal squamous cell carcinoma, with the low expression of phosphatase and tensin homolog and the high expression of the mammalian target of rapamycin component proteins (both total and phosphorylated) in tumor tissue. Our result might offer a new strategy for specific targeted therapy and prognostic assessment in esophageal cancer.

DEPTOR suppresses the progression of esophageal squamous cell carcinoma and predicts poor prognosis

As a naturally occurring inhibitor of mTOR, accumulated evidence has suggested that DEPTOR plays a pivotal role in suppressing the progression of human malignances. However, the function of DEPTOR in the development of esophageal squamous cell carcinoma (ESCC) is still unclear. Here we report that the expression of DEPTOR is significantly reduced in tumor tissues derived from human patients with ESCC, and the downregulation of DEPTOR predicts a poor prognosis of ESCC patients. In addition, we found that the expression of DEPTOR negatively regulates the tumorigenic activities of ESCC cell lines (KYSE150, KYSE510 and KYSE190). Furthermore, ectopic DEPTOR expression caused a significant suppression of the cellular proliferation, migration and invasion of KYSE150 cells, which has the lowest expression level of DEPTOR in the three cell lines. Meanwhile, CRISPR/Cas9 mediated knockout of DEPTOR in KYSE-510 cells significantly promoted cellular proliferation, migration and invasion. In addition, in vivo assays further revealed that tumor growth was significantly inhibited in xenografts with ectopic DEPTOR expression as compared to untreated KYSE150 cells, and was markedly enhanced in DEPTOR knockout KYSE-510 cells. Biochemical studies revealed that overexpression of DEPTOR led to the suppression of AKT/mTOR pathway as evidenced by reduced phosphorylation of AKT, mTOR and downstream SGK1, indicating DEPTOR might control the progression of ESCC through AKT/mTOR signaling pathway. Thus, these findings, for the first time, demonstrated that DEPTOR inhibits the tumorigenesis of ESCC cells and might serve as a potential therapeutic target or prognostic marker for human patients with ESCC.

UCP2 inhibition induces ROS/Akt/mTOR axis: Role of GAPDH nuclear translocation in genipin/everolimus anticancer synergism

Several studies indicate that mitochondrial uncoupling protein 2 (UCP2) plays a pivotal role in cancer development by decreasing reactive oxygen species (ROS) produced by mitochondrial metabolism and by sustaining chemoresistance to a plethora of anticancer drugs. Here, we demonstrate that inhibition of UCP2 triggers Akt/mTOR pathway in a ROS-dependent mechanism in pancreatic adenocarcinoma cells. This event reduces the antiproliferative outcome of UCP2 inhibition by genipin, creating the conditions for the synergistic counteraction of cancer cell growth with the mTOR inhibitor everolimus. Inhibition of pancreatic adenocarcinoma cell growth and induction of apoptosis by genipin and everolimus treatment are functionally related to nuclear translocation of the cytosolic glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). The synthetic compound (S)-benzyl-2-amino-2-(S)-3-bromo-4,5-dihydroisoxazol-5-yl-acetate (AXP3009), which binds GAPDH at its redox-sensitive Cys152, restores cell viability affected by the combined treatment with genipin and everolimus, suggesting a role for ROS production in the nuclear translocation of GAPDH. Caspase-mediated apoptosis by genipin and everolimus is further potentiated by the autophagy inhibitor 3-methyladenine revealing a protective role for Beclin1-mediated autophagy induced by the treatment. Mice xenograft of pancreatic adenocarcinoma further confirmed the antiproliferative outcome of drug combination without toxic effects for animals. Tumor masses from mice injected with UCP2 and mTOR inhibitors revealed a strong reduction in tumor volume and number of mitosis associated with a marked GAPDH nuclear positivity. Altogether, these results reveal novel mechanisms through which UCP2 promotes cancer cell proliferation and support the combined inhibition of UCP2 and of Akt/mTOR pathway as a novel therapeutic strategy in the treatment of pancreatic adenocarcinoma.

ΔNp63 activates the Fanconi anemia DNA repair pathway and limits the efficacy of cisplatin treatment in squamous cell carcinoma

TP63, a member of the p53 gene family gene, encodes the ΔNp63 protein and is one of the most frequently amplified genes in squamous cell carcinomas (SCC) of the head and neck (HNSCC) and lungs (LUSC). Using an epiallelic series of siRNAs with intrinsically different knockdown abilities, we show that the complete loss of ΔNp63 strongly impaired cell proliferation, whereas partial ΔNp63 depletion rendered cells hypersensitive to cisplatin accompanied by an accumulation of DNA damage. Expression profiling revealed wide-spread transcriptional regulation of DNA repair genes and in particular Fanconi anemia (FA) pathway components such as FANCD2 and RAD18 - known to be crucial for the repair of cisplatin-induced interstrand crosslinks. In SCC patients ΔNp63 levels significantly correlate with FANCD2 and RAD18 expression confirming ΔNp63 as a key activator of the FA pathway in vivo Mechanistically, ΔNp63 bound an upstream enhancer of FANCD2 inactive in primary keratinocytes but aberrantly activated by ΔNp63 in SCC. Consistently, depletion of FANCD2 sensitized to cisplatin similar to depletion of ΔNp63. Together, our results demonstrate that ΔNp63 directly activates the FA pathway in SCC and limits the efficacy of cisplatin treatment. Targeting ΔNp63 therefore would not only inhibit SCC proliferation but also sensitize tumors to chemotherapy.

Polymorphisms in the AKT1 and AKT2 genes and oesophageal squamous cell carcinoma risk in an Eastern Chinese population

Ethnic Han Chinese are at high risk of developing oesophageal squamous cell carcinoma (ESCC). Aberrant activation of the AKT signalling pathway is involved in many cancers, including ESCC. Some single nucleotide polymorphisms (SNPs) in genes involved in this pathway may contribute to ESCC susceptibility. We selected five potentially functional SNPs in AKT1 (rs2494750, rs2494752 and rs10138277) and AKT2 (rs7254617 and rs2304186) genes and investigated their associations with ESCC risk in 1117 ESCC cases and 1096 controls in an Eastern Chinese population. None of individual SNPs exhibited an association with ESCC risk. However, the combined analysis of three AKT1 SNPs suggested that individuals carrying one of AKT1 variant genotypes had a decreased ESCC risk [adjusted odds ratio (OR) = 0.60, 95% CI = 0.42-0.87]. Further stratified analysis found that AKT1 rs2294750 SNP was associated with significantly decreased ESCC risk among women (adjusted OR = 0.63, 95% CI = 0.43-0.94) and non-drinkers (OR = 0.79, 95% CI = 0.64-0.99). Similar protective effects on women (adjusted OR = 0.56, 95% CI = 0.37-0.83) and non-drinker (adjusted OR = 0.75, 95% CI = 0.60-0.94) were also observed for the combined genotypes of AKT1 SNPs. Consistently, logistic regression analysis indicated significant gene-gene interactions among three AKT1 SNPs (P < 0.015). A three-AKT1 SNP haplotype (C-A-C) showed a significant association with a decreased ESCC risk (adjusted OR = 0.70, 95% CI = 0.52-0.94). Multifactor dimensionality reduction analysis confirmed a high-order gene-environment interaction in ESCC risk. Overall, we found that three AKT1 SNPs might confer protection against ESCC risk; nevertheless, these effects may be dependent on other risk factors. Our results provided evidence of important gene-environment interplay in ESCC carcinogenesis.

The mTOR pathway in obesity driven gastrointestinal cancers: Potential targets and clinical trials

The mechanistic target of rapamycin (mTOR) is a crucial point of convergence between growth factor signalling, metabolism, nutrient status and cellular proliferation. The mTOR pathway is heavily implicated in the progression of many cancers and is emerging as an important driver of gastrointestinal (GI) malignancies. Due to its central role in adapting metabolism to environmental conditions, mTOR signalling is also believed to be critical in the development of obesity. Recent research has delineated that excessive nutrient intake can promote signalling through the mTOR pathway and possibly evoke changes to cellular metabolism that could accelerate obesity related cancers. Acting through its two effector complexes mTORC1 and mTORC2, mTOR dictates the transcription of genes important in glycolysis, lipogenesis, protein translation and synthesis and has recently been defined as a central mediator of the Warburg effect in cancer cells. Activation of the mTOR pathway is involved in both the pathogenesis of GI malignancies and development of resistance to conventional chemotherapy and radiotherapy. The use of mTOR inhibitors is a promising therapeutic option in many GI malignancies, with greatest clinical efficacy seen in combination regimens. Recent research has also provided insight into crosstalk between mTOR and other pathways which could potentially expand the list of therapeutic targets in the mTOR pathway. Here we review the available strategies for targeting the mTOR pathway in GI cancers. We discuss current clinical trials of both established and novel mTOR inhibitors, with particular focus on combinations of these drugs with conventional chemotherapy, radiotherapy and targeted therapies.

SPINK1 Status in Colorectal Cancer, Impact on Proliferation, and Role in Colitis-Associated Cancer

Colorectal cancer is a major cause of deaths due to cancer; therefore, research into its etiology is urgently needed. Although it is clear that chronic inflammation is a risk factor for colorectal cancer, the details remain uncertain. Serine protease inhibitor, Kazal type 1 (SPINK1) is mainly produced in pancreatic acinar cells. However, SPINK1 is expressed in various cancers and in inflammatory states, such as colon cancer and inflammatory bowel disease. There are structural similarities between SPINK1 and epidermal growth factor (EGF). Hence, it was hypothesized that SPINK1 functions as a growth factor for tissue repair in inflammatory states, and if prolonged, acts as a promoter for cell proliferation in cancerous tissues. Here, immunohistochemical staining for SPINK1 was observed in a high percentage of colorectal cancer patient specimens and SPINK1 induced proliferation of human colon cancer cell lines. To clarify its role in colon cancer in vivo, a mouse model exposed to the colon carcinogen azoxymethane and nongenotoxic carcinogen dextran sodium sulfate revealed that Spink3 (mouse homolog of SPINK1) is overexpressed in cancerous tissues. In Spink3 heterozygous mice, tumor multiplicity and tumor volume were significantly decreased compared with wild-type mice. These results suggest that SPINK1/Spink3 stimulates the proliferation of colon cancer cells and is involved in colorectal cancer progression.

IMPLICATIONS

Evidence suggests that SPINK1 is an important growth factor that connects chronic inflammation and cancer.

Associations of PI3KR1 and mTOR polymorphisms with esophageal squamous cell carcinoma risk and gene-environment interactions in Eastern Chinese populations

Single nucleotide polymorphisms (SNPs) in the PI3K/PTEN/AKT/mTOR signaling pathway may contribute to carcinogenesis. We genotyped five potentially functional PIK3R1 and mTOR SNPs in 1116 esophageal squamous cell cancer (ESCC) patients and 1117 cancer-free controls to assess their associations with ESCC risk. We observed no association with ESCC risk for any of the selected SNPs. However, the combined analysis of these SNPs revealed that subjects with one-to-three risk genotypes had an increased ESCC risk. Stratified analysis by body mass index (BMI) found that ESCC risk was significantly associated with each of three mTOR SNPs among subjects with BMI < 25.0. Specifically, we found that subjects carrying ≥ 1 risk genotypes had significantly increased ESCC risk, particularly for males, ever-smokers, ever-drinkers, and those with age > 60, or BMI < 25.0. Moreover, three mTOR haplotypes were associated with an increase in ESCC risk. Our meta-analysis of mTOR rs2295080 and cancer risk provided further evidence that mTOR SNPs might modulate cancer susceptibility. In this population, such risk effects might be modified by other risk factors, highlighting the importance of gene-environment interaction in esophageal carcinogenesis. Additional, larger studies are warranted to validate our findings.

The 4E-BP1/eIF4E ratio is a determinant for rapamycin response in esophageal cancer cells

OBJECTIVES

Rapamycin inhibits products of molecular pathways in esophageal squamous cell carcinoma and limits tumor cell growth by targeting 4E-BP1- and eIF4E-dependent gene translation. In this study, we investigate the influence of 4E-BP1-to-eIF4E ratio on rapamycin response in esophageal squamous cell carcinoma cells, and the underlying mechanism is discussed.

METHODS

The response to rapamycin treatment was examined in 6 esophageal cancer cell lines. Adjustment of the 4E-BP1/eIF4E ratio was carried out by knockdown or overexpression of 4E-BP1 and eIF4E. The relationship between Egr-1 and 4E-BP1 expression in esophageal cancer cells was also studied.

RESULTS

The 4E-BP1/eIF4E ratio was adjusted to evaluate the response to rapamycin treatment in TE1 and TE2 esophageal cancer cells. TE2 cells are sensitized to rapamycin treatment after overexpression of 4E-BP1 or knockdown of eIF4E; TE1 cells become resistant to rapamycin after knockdown of 4E-BP1 or overexpression of eIF4E. These data suggest that the 4E-BP1/eIF4E ratio is a determinant for the response of TE1 and TE2 cells to rapamycin treatment. Egr-1 expression was higher in TE2 cells compared with other esophageal cancer cell lines, and its knockdown increased 4E-BP1 expression in TE2 cells, which became sensitive to rapamycin treatment.

CONCLUSIONS

The 4E-BP1/eIF4E ratio is a determinant of the response of rapamycin treatment in esophageal cancer cells. Egr-1 can reduce 4E-BP1 gene expression and render esophageal squamous cell carcinoma cells resistant to rapamycin with a relatively low 4E-BP1/eIF4E ratio. Thus, the 4E-BP1/eIF4E ratio may represent a therapeutic index for the prediction of clinical outcome of rapamycin treatment in patients with esophageal squamous cell carcinoma.

EF24 and RAD001 potentiates the anticancer effect of platinum-based agents in human malignant pleural mesothelioma (MSTO-211H) cells and protects nonmalignant mesothelial (MET-5A) cells

The most widespread neoplasm of the pleura is malignant pleural mesothelioma (MPM) with low prevalence rate. The mechanistic target of rapamycin signaling pathway, inhibited by RAD001, was shown to be deregulated in MPM development and considered a novel target for the MPM therapy. The EF24, a curcumin analog, also affects several signaling pathways and kills cancer cells as a single agent or in combination with classical drugs. We aimed to evaluate possible effects of RAD001, EF24, cisplatin, and oxaliplatin treatments on both malignant pleural mesothelioma (MSTO-211H) and nonmalignant mesothelial (Met-5A) cell lines. The effects of the agents on MSTO-211H and Met-5A cells were evaluated in terms of cell viability, cytotoxicity, DNA synthesis rate, quantitation of apoptotic DNA fragmentation, and cleaved caspase 3 levels. Moreover, quantitative messenger RNA (mRNA) analysis of apoptotic (CASP9) and antiapoptotic (BCL2L1 and BCL2) genes were also performed. We found that both EF24 and RAD001 alone treatments decreased only MSTO-211H cell viability, but cisplatin and oxaliplatin affected both cell lines. Pretreatment with EF24 or RAD001 followed by cisplatin increased the effects of cisplatin alone application. EF24 and RAD001 pretreatment decreased DNA fragmentation rate when compared with cisplatin alone treatment in Met-5A cells. Sequential treatments resulted in a significant increase of CASP9 mRNA expression in MSTO-211H cells but not in Met-5A cells. Our preliminary results suggest that pretreatment with EF24 or RAD001 may reduce cytotoxic effect of cisplatin on nonmalignant mesothelial cells and increase cell death response of MPM cells. Further analyses using animal models are needed to confirm these findings in vivo.

Inhibition of mammalian target of rapamycin by rapamycin increases the radiosensitivity of esophageal carcinoma Eca109 cells

The aim of the present study was to investigate whether radiation induces the mammalian target of rapamycin (Rap) (mTOR) signaling pathway in esophageal carcinoma Eca109 cells, and whether mTOR inhibition by rapamycin increases Eca109 cell radiosensitivity. Changes in the levels of mTOR signaling pathway and DNA damage-repair proteins in Eca109 cells prior to and following radiation were determined. The Eca109 cells were treated with Rap (0, 100, 200 and 400 nmol/l) in combination with radiation (0, 2, 4 and 6 Gy). The cell proliferation inhibition rate was determined by MTT assay. The optimum Rap concentration and radiation dose, which appropriately inhibited cell proliferation, were then selected for further study. An appropriate combination of Rap and radiation for the Eca109 cells was also selected and changes in the mTOR signaling pathway, apoptosis and DNA damage-repair proteins, as well as in cell clone formation, survival curves, the apoptosis rate and radiation-induced DNA damage were determined. The expression of the mTOR signaling pathway and DNA damage-repair proteins were found to increase following the irradiation of the Eca109 cells. In addition, Rap was found to inhibit the mTOR signaling pathway and the expression of the DNA damage-repair proteins. At the same radiation dose, with increasing Rap concentration, the proliferation inhibition rates of the Eca109 cells were found to improve. The clone formation and survival curves of the experimental group were less than those of the control groups. Furthermore, the cell apoptosis rate and expression of cleaved caspase-3 and bax in the experimental group were higher than those of the control groups, whereas the expression of bcl-2 was less than that of the control groups. The radiation-induced DNA damage of the experimental group was greater than that of the control group. The inhibition of mTOR by Rap was found to effectively inhibit the proliferation, survival and radiation-induced DNA damage repair of the Eca109 cells following irradiation, as well as promoting radiation-induced apoptosis, thereby increasing the radiosensitivity of the esophageal carcinoma Eca109 cells.

Targeted therapies in metastatic esophageal cancer: advances over the past decade

Esophageal cancer is one of the most aggressive malignancies of the upper aerodigestive tract. Despite advances in surgical techniques and multi-modality therapies, the 5-year survival rate remains poor (14%). Over the past decade, efforts have been focused on the field of drug development with the advancement of novel molecularly targeted therapeutic agents. These agents target a variety of cancer relevant pathways such as vascular endothelial growth factor (VEGF) or its receptor, the cyclooxygenase-2 (COX-2), epidermal growth factor receptor (EGFR), and mammalian target of rapamycin (mTOR) pathways. The number of approved targeted agents remains few, with HER-2 inhibitors leading the list for treatment of HER-2 expressing metastatic adenocarcinomas. Novel agents have not yet been widely explored in esophageal cancer. In this review, we will provide a concise and systematic overview of the development of novel targeted therapies currently under investigation for the treatment of metastatic esophageal disease.

Role of mTOR inhibitor in cholangiocarcinoma cell progression

Cholangiocarcinoma (CCA) is a lethal malignancy of the biliary epithelium. CCA is resistant to currently available chemotherapy; therefore, new drugs as well as new molecular targets must be identified for the development of an effective treatment for CCA. The present study showed that RAD001 (everolimus), a derivative of rapamycin and an orally bioavailable mammalian target of rapamycin (mTOR) inhibitor, exhibits cytotoxic and antimetastatic effects in a CCA cell line, RMCCA-1. Treatment with low concentrations of RAD001 resulted in a significant reduction of in vitro invasion and migration of RMCCA-1, concomitant with a reduction of filopodia and alteration of the actin cytoskeleton. Although, matrix metalloproteinase-9 and -14 activities were unaltered. However, at high concentrations, RAD001 exhibited cytotoxic effects, reducing cell proliferation and inducing apoptotic cell death. Overall, RAD001 exhibits multiple effects mediated by the inhibition of the mTOR, which may serve as a promising agent for the treatment of CCA.

Small molecule agonists of PPAR-γ exert therapeutic effects in esophageal cancer

The transcription factor PPAR-γ plays various roles in lipid metabolism, inflammation, cellular differentiation, and apoptosis. PPAR-γ agonists used to treat diabetes may have utility in cancer treatment. Efatutazone is a novel later generation PPAR-γ agonist that selectively activates PPAR-γ target genes and has antiproliferative effects in a range of malignancies. In this study, we investigated PPAR-γ status in esophageal squamous cell carcinoma (ESCC) and investigated the antiproliferative effects of efatutazone. PPAR-γ was expressed heterogeneously in ESCC, in which it exhibited an inverse relationship with Ki-67 expression. PPAR-γ expression was associated independently with good prognosis in ESCC. Efatutazone, but not the conventional PPAR-γ agonist troglitazone, inhibited ESCC cell proliferation in vitro and in vivo. Mechanistic investigations suggested that efatutazone acted by upregulating p21Cip1 protein in the nucleus through inactivation of the Akt pathway and dephosphorylation of p21Cip1 at Thr145 without affecting the transcriptional activity of p21Cip1. We also found that treatment with efatutazone led to phosphorylation of the EGF receptor and activation of the mitogen-activated protein kinase (MAPK) pathway. Accordingly, the combination of efatutazone with the antiepithelial growth factor receptor antibody cetuximab synergized to negatively regulate the phosphoinositide 3-kinase-Akt and MAPK pathways. Together, our results suggest that efatutazone, alone or in combination with cetuximab, may offer therapeutic effects in ESCC.

Esophageal carcinoma: are modern targeted therapies shaking the rock?

PURPOSE OF REVIEW

Our current review aims to outline recent progress in the development of modern targeted therapeutic regimens for esophageal cancer.

RECENT FINDINGS

Esophageal cancers demonstrate marked molecular heterogeneity. Modern technology increasingly allows us to identify subgroups of patients whose tumors fit particular molecular profiles. Tumor-based human epidermal growth factor receptor 2 (HER-2) analysis has become a standard part of the work-up for patients with tumors of the esophagogastric junction. The anti-HER-2 antibody, trastuzumab, when added to a chemotherapeutic regimen combining a fluoropyrimidine and platinum, provides a survival benefit for those patients with HER-2 overexpression and/or amplification. Despite large coordinated efforts to establish the efficacy of additional targeted therapeutics, to this point minimal additional benefit has been realized in affecting prominent molecular targets, such as vascular endothelial growth factor and epidermal growth factor receptor, in esophageal cancer. Multiple targets of interest remain under investigation with some early encouraging data. These targets include mammalian target of rapamycin, c-MET, insulin like growth factor 1 receptor and cytotoxic T-lymphocyte antigen 4. Additional improvements in therapy may stem from improved patient selection for combinations of standard cytotoxic regimens, such as platinum-based regimens.

SUMMARY

Targeted therapeutics have yielded early benefit, but further progress will require a deeper understanding of this disease, improved identification of subpopulations who may derive greater benefit, and continued multicenter efforts to conduct the necessary clinical investigations.

Polymorphisms in mTORC1 genes modulate risk of esophageal squamous cell carcinoma in eastern Chinese populations

INTRODUCTION

Mammalian target of rapamycin complex 1 (mTORC1) is an evolutionary conserved multiprotein complex that functions as a key regulator of gene transcription, protein translation, and autophagy. No studies have assessed associations between functional single nucleotide polymorphisms (SNPs) in mTORC1 genes and risk of esophageal squamous cell carcinoma (ESCC).

METHODS

: In a case-control study of 1126 ESCC patients and 1131 cancer-free controls, we genotyped eight SNPs in mTORC1 (mTOR rs1883965 G>A and rs2536 T>C, mLST8 rs3160 C>T and rs26865 G>A, RPTOR rs3751934 C>A, rs1062935 T>C, rs3751932 T>C and rs12602885 G>A) and assessed their associations with risk of ESCC.

RESULTS

In the single-locus analyses, we found a significantly altered risk of ESCC associated with mTOR rs1883965 A variant genotypes (adjusted OR = 1.27 and 1.26; 95% confidence interval = 1.01-1.60 and 1.01-1.58 for GA and GA/AA, respectively, compared with GG) but not with other SNPs. In the combined analysis of the eight SNPs, we found individuals with two or more unfavorable genotypes exhibited an increased risk for ESCC (adjusted OR = 1.35; 95% confidence interval = 1.20-1.62), compared with those with less than two unfavorable genotypes. Such a cumulative effect was dose-dependent (ptrend = 0.004). In the multiple dimension reduction analysis, mTOR rs1883965 was consistently suggested as the strongest individual factor for ESCC risk, and the model including all SNPs yielded the lowest prediction error of 17.66% for model validation.

CONCLUSIONS

These findings suggest that functional SNPs of mTORC1 genes may individually or collectively contribute to ESCC risk. Further validation of these findings is warranted.

Cisplatin-Based Chemotherapy Options for Recurrent and/or Metastatic Squamous Cell Cancer of the Head and Neck

Recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC) is a devastating malignancy with a poor prognosis. Treatment is limited to chemotherapeutic approaches. Cisplatin is an established and effective treatment for R/M HNSCC, and many studies have investigated cisplatin treatment in combination with other agents. Even when being treated with first line therapy (cisplatin + 5-fluorouracil + cetuximab), overall survival is only 10 months, indicating the need for novel chemotherapeutics and treatment regimens. Current research is focused on molecular targeting therapies inhibiting epidermal growth factor receptor, phosphoinositide-3-kinase/Akt/mammalian target of rapamycin, and vascular endothelial growth factor pathways. A variety of clinical trials have been completed and are currently underway with encouraging results. Finally, future directions of cisplatin-based R/M HNSCC treatment may include targeting specific pathways known to induce cisplatin resistance, such as nucleotide excision repair and inhibition of apoptosis, in hopes to enhance response to cisplatin therapy.

Targeted treatments for metastatic esophageal squamous cell cancer

Squamous cell carcinoma, one of the two major sub-types of esophageal carcinomas, constitutes the great majority of tumors in the upper and middle third of the organ. Declining in incidence in western countries, it continues to be a significant public health problem in the far east. Targeted treatments are novel therapies introduced in the clinical therapeutic armamentarium of oncology in the last 10-15 years. They represent a rational way of treating various cancers based on their molecular lesions. Although no such agent has been approved so far for the treatment of esophageal squamous cell carcinomas (ESCC), several are in clinical trials and several others have displayed pre-clinical activity that would justify the efforts and risks of pursuing their clinical development in this disease. This paper discusses some of these targeted agents in more advanced development in metastatic ESCC, as well as some promising drugs with pre-clinical or initial clinical data in the disease.

Messenger RNA and protein expression of thymidylate synthase and DNA repair genes in thymic tumors

BACKGROUND

Thymic epithelial tumors include several entities with different biologic behavior. Chemotherapy is indicated in advanced disease, but limited data exist on gene expression correlation with the response to chemotherapeutic agents.

PATIENTS AND METHODS

A series of 69 thymic neoplasms (7 A-, 6 AB-, 6 B1-, 10 B2-, 14 B3-thymomas, 22 carcinomas and 4 combined tumors) was collected to assess gene expression of thymidylate synthase (TS), excision repair cross complementing-1 (ERCC1), ribonucleotide reductase subunit 1 (RRM1), topoisomerase 2α (TOP2A) and mTOR.

RESULTS

A strong linear correlation between TS gene and protein expression was observed (P<0.0001, R=0.40). TS expression was significantly lower in pure A-thymomas and thymic carcinomas (P<0.0001) and progressively decreasing from B1-type to thymic carcinomas (B1>B2>B3>C; P<0.0001). RRM1 and TOP2A mRNA expression levels were significantly correlated with TS levels (both P=0.03) with a similar trend of expression among histotypes. RRM1 and TOP2A high levels were significantly correlated with high TS (P=0.03) and low tumor stages (I-II) (P<0.0001 and P<0.01, respectively). No relevant changes of ERCC1 and mTOR were detected.

CONCLUSIONS

Low TS and, to a minor extent, RRM1 and TOP2A expression were detected in aggressive thymic tumors. These findings should be prospectively considered in selecting the most appropriate chemotherapy.

Everolimus combined with cisplatin has a potential role in treatment of urothelial bladder cancer

Cisplatin (CDDP)-based chemotherapy is a commonly treatment for advanced urothelial carcinoma. However, episodes of cisplatin resistance have been referenced. Recently it has been reported that everolimus (RAD001) could have an important role to play in bladder-cancer treatment and that mTOR inhibitors may restore chemosensitivity in resistant tumours. The aim of this study was to assess RAD001 in vitro ability to enhance CDDP cytotoxicity in three human bladder-cancer cell lines. Over the course of 72h, the cells were exposed to different concentrations of CDDP and RAD001, isolated or combined. Treatment with CDDP statistically (P<0.05) decreased cell proliferation in cell lines in a dose-dependent manner. The anti-proliferative activity of CDDP used in combination with RAD001 was statistically significant (P<0.05) in the cell lines at all concentrations tested. RAD001 had a therapeutic effect when used in combination with CDDP and could therefore be a useful anti-cancer drug combination for patients with bladder cancer.

Pharmacological targeting of mammalian target of rapamycin inhibits ovarian granulosa cell tumor growth

Few targeted therapies have been developed for ovarian granulosa cell tumor (GCT), even though it represents 5% of all malignant ovarian tumors in women. As misregulation of PI3K/AKT signaling has been implicated in GCT development, we hypothesized that the AKT signaling effector mammalian target of rapamycin (mTOR) may play a role in the pathogenesis of GCT and could represent a therapeutic target. Analyses of human GCT samples showed an increase in protein levels of mTOR and its downstream effectors RPS6KB1, RPS6, eIF4B and PPARG relative to normal granulosa cells, suggestive of an increase in mTOR pathway activity and increased translational activity and/or protein stability. We next sought to evaluate mTOR as a GCT therapeutic target using the Pten (tm1Hwu/tmiHwu);Ctnnb1 (tm1Mmt/+);Amhr2 (tm3(cre)Bhr/+) (PCA) mouse model, in which mTOR, RPS6KB1, eIF4B and PPARG are upregulated in tumor cells in a manner similar to human GCT. Treatment of PCA mice with the mTOR-specific inhibitor everolimus reduced tumor growth rate (1.5-fold; P < 0.05) and also reduced total tumor burden (4.7-fold; P < 0.05) and increased survival rate (78 versus 44% in the vehicle group) in a PCA surgical model of GCT peritoneal carcinomatosis. Everolimus decreased tumor cell proliferation and tumor cell volume relative to controls (P < 0.05), whereas apoptosis was unaffected. Phosphorylation of RPS6KB1 and RPS6 were decreased (P < 0.05) by everolimus, but RPS6KB1, RPS6, eIF4B and PPARG expressions were not affected. These results suggest that mTOR is a valid and clinically useful pharmacological target for the treatment of GCT, although its inhibition does not reverse all consequences of aberrant PI3K/AKT signaling in the PCA model.