The prognostic role of mTOR and p-mTOR for survival in non-small cell lung cancer: a systematic review and meta-analysis

The potential role of circular RNAs -regulated PI3K signaling in non-small cell lung cancer: Molecular insights and clinical perspective

Non-small cell lung cancer (NSCLC), accounting for more than 80% of all cases, is the predominant form of lung cancer and the leading cause of cancer-related deaths worldwide. Significant progress has been made in diagnostic techniques, surgical interventions, chemotherapy protocols, and targeted therapies at the molecular level, leading to enhanced treatment outcomes in patients with NSCLC. Extensive evidence supports the use of circular RNAs (circRNAs), a specific category of naturally occurring non-coding small RNAs (ncRNAs), for the diagnosis, monitoring of treatment efficacy, and assessment of survival in NSCLC. CircRNAs have been identified to play significant roles in various aspects of cancer formation, either as tumor suppressors or tumor promoters, contributing to cancer development through several signaling pathways, including the phosphoinositide 3-kinases (PI3Ks) pathway. This pathway is well-established because of its regulatory role in essential cellular processes. CircRNAs regulate the PI3K/AKT pathway by targeting diverse cellular elements. This review aims to provide insight into the involvement of several circRNAs linked to the PI3K/AKT pathway in NSCLC.

Low-Level Expression of p-S6 Is Associated with Nodal Metastasis in Patients with Head and Neck Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer. The incidence of metastasis for cSCC is estimated to be around 1.2-5%. Ribosomal protein S6 (p-S6) and the p21 protein (p21) are two proteins that play central roles in other cancers. These proteins may be equally important in cSCC, and together, these could constitute a good candidate for metastasis risk assessment of these patients. We investigate the relationship of p-S6 and p21 expression with the impact on the prognosis of head and neck cSCC (cSCCHN). p-S6 and p21 expression was analyzed by immunohistochemistry on paraffin-embedded tissue samples from 116 patients with cSCCHN and associations sought with clinical characteristics. Kaplan-Meier estimators and Cox proportional hazard regression models were also used. The expression of p-S6 was significantly inversely associated with tumor thickness, tumor size, desmoplastic growth, pathological stage, perineural invasion and tumor buds. p21 expression was significantly inversely correlated with >6 mm tumor thickness, desmoplastic growth, and perineural invasion. p-S6-negative expression significantly predicted an increased risk of nodal metastasis (HR = 2.63, 95% CI 1.51-4.54; p < 0.001). p21 expression was not found to be a significant risk factor for nodal metastasis. These findings demonstrate that p-S6-negative expression is an independent predictor of nodal metastasis. The immunohistochemical expression of p-S6 might aid in better risk stratification and management of patients with cSCCHN.

Expression of mTOR in normal and pathological conditions

The mechanistic/mammalian target of rapamycin (mTOR), a protein discovered in 1991, integrates a complex pathway with a key role in maintaining cellular homeostasis. By comprising two functionally distinct complexes, mTOR complex 1 (mTORC1) and mTORC2, it is a central cellular hub that integrates intra- and extracellular signals of energy, nutrient, and hormone availability, modulating the molecular responses to acquire a homeostatic state through the regulation of anabolic and catabolic processes. Accordingly, dysregulation of mTOR pathway has been implicated in a variety of human diseases. While major advances have been made regarding the regulators and effectors of mTOR signaling pathway, insights into the regulation of mTOR gene expression are beginning to emerge. Here, we present the current available data regarding the mTOR expression regulation at the level of transcription, translation and mRNA stability and systematize the current knowledge about the fluctuations of mTOR expression observed in several diseases, both cancerous and non-cancerous. In addition, we discuss whether mTOR expression changes can be used as a biomarker for diagnosis, disease progression, prognosis and/or response to therapeutics. We believe that our study will contribute for the implementation of new disease biomarkers based on mTOR as it gives an exhaustive perspective about the regulation of mTOR gene expression in both normal and pathological conditions.

The roles of CPSF6 in proliferation, apoptosis and tumorigenicity of lung adenocarcinoma

Cleavage and polyadenylation specific factor 6 (CPSF6), a member of serine/arginine-rich protein family, is implicated in HIV-1-infection and replication. Overexpression of CPSF6 predicts poor prognostic outcomes of breast cancer. However, the expression and possible function of CPSF6 in lung adenocarcinoma (LUAD) still needs to be explored. Here, we found that CPSF6 is significantly higher expressed in tumor tissues than normal tissues in multiple cancer types. Besides, CPSF6 plays a significant risky role in LUAD that is associated with overall survival (HR=1.337, P=0.051) and disease-specific survival (HR=1.4739, P=0.042). CPSF6 mRNA was up-regulated in LUAD tissues by analyzing publicly available datasets from Gene Expression Omnibus (GEO). Further survival analysis on The Cancer Genome Atlas (TCGA) dataset suggested a close correlation between CPSF6 expression and overall survival, and disease-free survival of LUAD patients. Inhibition of CPSF6 expression by lentivirus-mediated RNA interference (RNAi) in two LUAD cell lines (A549 and NCH-H1299) caused a significant reduction in cell proliferation, colony formation and a notable induction in apoptotic rate. CPSF6 knockdown in xenograft tumors inhibited LUAD cell growth in vivo. Moreover, we identified differentially expressed genes with CPSF6 inhibition by Microarray analysis, and pathway analyses revealed that CPSF6 knockdown resulted in the dysregulation of the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway. Collectively, our results are the first to demonstrate that CPSF6 functions as an oncoprotein by regulating cancer-related pathways in LUAD.

Histological and Immunohistochemical Evaluation of Phosphorylated Mechanistic Target of Rapamycin in Canine Skin Tumours

The mechanistic target of rapamycin (mTOR) plays an important role in cellular functions, including growth and metabolism. Recently, mTOR and the activated phosphorylated form of mTOR (p-mTOR) have been reported as potential prognostic markers in many human tumours. However, there are few studies on its activation in canine tumours. We investigated the expression of p-mTOR in 17 canine skin tumours (CSTs), of which 58.8% were epithelial and melanocytic and 41.2% were mesenchymal tumours. Seventy-six per cent of the CSTs had high or moderate expression of p-mTOR. Mean p-mTOR expression in the epithelial and melanocytic tumours (5.7 ± 0.56) was significantly higher (P <0.05) than that of the mesenchymal tumours (3.14 ± 0.55). The age of the animals had no influence on p-mTOR expression. These findings suggest that activation of m-TOR is important in the development of skin tumours in dogs and the study might form the basis for further research on utilizing m-TOR inhibitors as improved therapeutic modalities in canine skin tumours.

EGFR/c-Met and mTOR signaling are predictors of survival in non-small cell lung cancer

BACKGROUND

EGFR/c-Met activation/amplification and co-expression, mTOR upregulation/activation, and Akt/Wnt signaling upregulation have been individually associated with more aggressive disease and characterized as potential prognostic markers for lung cancer patients.

METHODS

Tumors obtained from 109 participants with stage I-IV non-small cell lung cancer (NSCLC) were studied for EGFR/c-Met co-localization as well as for total and active forms of EGFR, c-Met, mTOR, S6K, beta-catenin, and Axin2. Slides were graded by two independent blinded pathologists using a validated scoring system. Protein expression profile correlations were assessed using Pearson correlation and Spearman's rho. Prognosis was assessed using Kaplan-Meier analysis.

RESULTS

Protein expression profile analysis revealed significant correlations between EGFR/p-EGFR (p = 0.0412) and p-mTOR/S6K (p = 0.0044). Co-localization of p-EGFR/p-c-Met was associated with increased p-mTOR (p = 0.0006), S6K (p = 0.0018), and p-S6K (p < 0.0001) expression. In contrast, active beta-catenin was not positively correlated with EGFR/c-Met nor any activated proteins. Axin2, a negative regulator of the Wnt pathway, was correlated with EGFR, p-EGFR, p-mTOR, p-S6K, EGFR/c-Met co-localization, and p-EGFR/p-c-Met co-localization (all p-values <0.03). Kaplan-Meier analysis revealed shorter median survival in participants with high expression of Axin2, total beta-catenin, total/p-S6K, total/p-mTOR, EGFR, and EGFR/c-Met co-localization compared with low expression. After controlling for stage of disease at diagnosis, subjects with late-stage disease demonstrated shorter median survival when exhibiting high co-expression of EGFR/c-Met (8.1 month versus 22.3 month, p = 0.050), mTOR (6.7 month versus 22.3 month, p = 0.002), and p-mTOR (8.1 month versus 25.4 month, p = 0.004) compared with low levels.

CONCLUSIONS

These findings suggest that increased EGFR/c-Met signaling is correlated with upregulated mTOR/S6K signaling, which may in turn be associated with shorter median survival in late-stage NSCLC.

mTOR-autophagy promotes pulmonary senescence through IMP1 in chronic toxicity of methamphetamine

It is growingly concerned about methamphetamine (MA)-induced lung toxicity. IMP1 is identified as a key molecule for cell life processes, but the role of IMP1 in MA-induced senescence remains unclear. The purpose of this study was to investigate whether chronic exposure to MA can cause autophagy and senescence of the lungs, whether there are interactions between Mammalian target of rapamycin (mTOR) and IMP1 and whether IMP1 is involved in pulmonary senescence promoted by mTOR-autophagy. The rats were randomly divided into control group and MA group, following by H&E staining, immunohistochemistry staining and Western blot. The alveolar epithelial cells were proceeded by ß-galactosidase staining, cell cycle detection, transfection and co-immunoprecipitation. Long-term exposure to MA led to the thickening of alveolar septum and more compact lungs. MA promoted the conversion of LC3-I to LC3-II and inhibited the activation of mTOR to induce autophagy. Bioinformatics and co-immunoprecipitation results presented the interactions between IMP1 and mTOR. MA induced cell senescence by decreasing IMP1, up-regulating p21 and p53, arresting cell cycle and increasing SA-β-gal. Overexpression of IMP1 reduced p21 and SA-β-gal to inhibit the senescence of alveolar epithelial cells. These results demonstrated that mTOR-autophagy promotes pulmonary senescence through IMP1 in chronic toxicity of methamphetamine.

An Overview of Promising Biomarkers in Cancer Screening and Detection

Applications of biomarkers have been proved in oncology screening, diagnosis, predicting response to treatment as well as monitoring the progress of the disease. Considering the crucial role played by them during different disease stages, it is extremely important to evaluate, validate, and assess them to incorporate them into routine clinical care. In this review, the role of few most promising and successfully used biomarkers in cancer detection, i.e. PD-L1, E-Cadherin, TP53, Exosomes, cfDNA, EGFR, mTOR with regard to their structure, mode of action, and reports signifying their pathological significance, are addressed. Also, an overview of some successfully used biomarkers for cancer medicine has been presented. The study also summarizes biomarker-driven personalized cancer therapy i.e., approved targets and indications, as per the US FDA. The review also highlights the increasingly prominent role of biomarkers in drug development at all stages, with particular reference to clinical trials. The increasing utility of biomarkers in clinical trials is clearly evident from the trend shown, wherein ~55 percent of all oncology clinical trials in 2019 were seen to involve biomarkers, as opposed to ~ 15 percent in 2001, which clearly proves the essence and applicability of biomarkers for synergizing clinical information with tumor progression. Still, there are significant challenges in the implementation of these possibilities with strong evidence in cost-- effective manner.

mTOR-Mediated Antioxidant Activation in Solid Tumor Radioresistance

Radiotherapy is widely used for the treatment of cancer patients, but tumor radioresistance presents serious therapy challenges. Tumor radioresistance is closely related to high levels of mTOR signaling in tumor tissues. Therefore, targeting the mTOR pathway might be a strategy to promote solid tumor sensitivity to ionizing radiation. Radioresistance is associated with enhanced antioxidant mechanisms in cancer cells. Therefore, examination of the relationship between mTOR signaling and antioxidant mechanism-linked radioresistance is required for effective radiotherapy. In particular, the effect of mTOR signaling on antioxidant glutathione induction by the Keap1-NRF2-xCT pathway is described in this review. This review is expected to assist in the identification of therapeutic adjuvants to increase the efficacy of radiotherapy.

mTOR Signaling in Cancer and mTOR Inhibitors in Solid Tumor Targeting Therapy

The mammalian or mechanistic target of rapamycin (mTOR) pathway plays a crucial role in regulation of cell survival, metabolism, growth and protein synthesis in response to upstream signals in both normal physiological and pathological conditions, especially in cancer. Aberrant mTOR signaling resulting from genetic alterations from different levels of the signal cascade is commonly observed in various types of cancers. Upon hyperactivation, mTOR signaling promotes cell proliferation and metabolism that contribute to tumor initiation and progression. In addition, mTOR also negatively regulates autophagy via different ways. We discuss mTOR signaling and its key upstream and downstream factors, the specific genetic changes in the mTOR pathway and the inhibitors of mTOR applied as therapeutic strategies in eight solid tumors. Although monotherapy and combination therapy with mTOR inhibitors have been extensively applied in preclinical and clinical trials in various cancer types, innovative therapies with better efficacy and less drug resistance are still in great need, and new biomarkers and deep sequencing technologies will facilitate these mTOR targeting drugs benefit the cancer patients in personalized therapy.

Impact of PI3K/AKT/mTOR pathway activation on the prognosis of patients with head and neck squamous cell carcinomas

The PI3K/AKT/mTOR signaling pathway has emerged as one of the most frequently deregulated in head and neck squamous cell carcinomas (HNSCC). Numerous alterations of various upstream and downstream components have been described; however, their prognostic significance and impact on HNSCC patient survival remains to be established. This was addressed using an unbiased cohort of 93 consecutive and homogeneous surgically treated HNSCC patients and results confirmed in 432 HNSCC patients. Our findings reveal the high prevalence of S6 phosphorylation, a surrogate marker of mTORC1 activation, in HNSCC specimens (>70%) and, more importantly, demonstrate its relevance on clinical outcome. Phosphorylation of ribosomal protein S6 on either Ser235/236 or Ser240/244 was consistently and significantly correlated with favorable prognosis, although with differences depending on the tumor site. Thus, p-S6 expression was significantly correlated with better disease-specific survival specifically in the subgroup of laryngeal carcinoma patients (P< 0.001). In addition, multivariate regression models revealed p-S6 to be an inverse and independent predictor of lymph-node metastasis (P= 0.004) and distant metastasis (P= 0.006). Taken together, this study unveils an unprecedented correlation of mTOR activation with improved clinical outcome in patients with laryngeal carcinomas and uncovers the potential of p-S6 expression as a good prognostic biomarker and an inverse predictor of lymph node and distant metastases. These results should be of broad interest as immunohistochemical detection of p-S6 may help to stratify patients and guide treatment decisions.

Prognostic values of EphB1/B2 and p-EphB1/B2 expression in non-small cell lung cancer

Erythropoietin-producing hepatocellular carcinoma (Eph) Receptor, as a family member of receptor tyrosine kinases (RTK), plays a critical role in modulating different cell behaviors. It is also closely related to tumorigenesis. However, little has been known about its prognostic values in non-small cell lung cancer (NSCLC). Thus, we studied the expression levels of EphB1/2 and p-EphB1/2 in both NSCLC tissue and normal lung tissue, and analyzed their correlations with clinicopathological characteristics as well as NSCLC patients' survival. In the present study, 156 NSCLC tissue samples and 28 distal normal lung tissue samples were collected from 156 NSCLC patients. Afterwards, the protein levels of EphB1/2 and p-EphB1/2 were detected by immunohistochemistry. Their prognostic values were also evaluated using both univariate and multivariate survival analysis. According to the results, 44.87% (70/156) NSCLC samples were detected with positive EphB1/2 expression, significantly higher than that in distal normal lung tissue (16%, 4/25); but no difference was found regarding to p-EphB1/2 expression. With respect to the clinicopathological characteristics, there was no significant correlation between protein levels and age, gender, histological type, differentiation status as well as TNM stage. Intriguingly, it showed a clear trend of increased EphB1/2-positive rate when tumor differentiation grade developed. In the survival analysis, a positive correlation was found between positive p-EphB1/2 expression and poor survival in female (P=0.001). Then N stage (P=0.001) and TNM stage (P<0.001) were found significantly related to patients' survival in multivariate analysis. Therefore, p-EphB1/2 may serve as a prognostic predictor in female NSCLC patients.

Fibrinogen promotes malignant biological tumor behavior involving epithelial-mesenchymal transition via the p-AKT/p-mTOR pathway in esophageal squamous cell carcinoma

PURPOSE

Hyperfibrinogenemia is associated with unfavorable prognosis and advanced tumor behavior in various malignancies, including esophageal squamous cell carcinoma (ESCC). However, its biological function in ESCC is unknown. The present study was designed to further validate the prognostic value of preoperative plasma hyperfibrinogenemia and evaluate the biological role of fibrinogen, as well as the underlying mechanism in ESCC.

METHODS

Data from 452 cases with newly diagnosed ESCC followed by curative surgery between 2006 and 2010 were retrospectively evaluated. The Clauss method was utilized to measure the preoperative plasma fibrinogen level. Correlations between the fibrinogen level and clinicopathologic characteristics and survival analysis were performed. The effects of fibrinogen on malignant behaviors, including tumor cell viability, colony formation, migration, and invasion, were also investigated.

RESULTS

The optimal cut-off value for plasma fibrinogen level was defined as 4.0 g/L according to recommendations. Thus, the proportion of hyperfibrinogenemia was 24.8% (112/452). Preoperative plasma hyperfibrinogenemia was significantly associated with advanced tumor length, deep tumor invasion, advanced tumor-node-metastasis stage, alcohol consumption, a higher white blood cell count, a higher platelet count, and high globulin levels. Univariate survival analysis revealed that compared to those with normal plasma fibrinogen levels, patients with hyperfibrinogenemia tended to have poorer disease-free survival (DFS) [hazard ratio (HR), 1.692; 95% confidence interval (CI), 1.304-2.196; P < 0.001] and overall survival (OS) (HR 1.864; 95% CI 1.424-2.440; P < 0.001). In the multivariate Cox regression models, these factors remained independent predictors for impaired DFS (HR 1.491; 95% CI 1.138-1.955; P = 0.004) and OS (HR 1.648; 95% CI 1.246-2.180; P < 0.001) after adjusting for other confounding variables. In addition, fibrinogen could significantly promote cell migration and invasion but not proliferation. Moreover, it could also induce epithelial-mesenchymal transition (EMT) and increase the levels of p-PTEN, p-AKT, and p-mTOR in ESCC cell lines.

CONCLUSIONS

Preoperative plasma hyperfibrinogenemia might serve as an independent predictor of unfavorable survival in ESCC. Furthermore, fibrinogen may promote cell motility by inducing EMT via the p-AKT/p-mTOR pathway.

Phosphorylated ribosomal protein S6 correlation with p21 expression and inverse association with tumor size in oral squamous cell carcinoma

BACKGROUND

The purpose of this study was to investigate the clinical relevance of phosphorylated ribosomal protein S6 (p-S6), a surrogate marker of mammalian target of rapamycin (mTOR) activation, and p21 in a series of 125 patients with oral squamous cell carcinomas (OSCCs).

METHODS

Immunohistochemical analysis was performed to ascertain the phosphorylation status of p-S6 at Ser235/236 and Ser240/244, p21, and p53 protein expression.

RESULTS

Expression of phosphorylated S6 protein on either serine 235/236 or serine 240/244 was detected in 83% and 88% tumors, respectively, and both of them were inversely and significantly correlated with the tumor size and local infiltration. Positive p21 expression was found in 91.5% of the cases, and was inversely correlated with tumor size. In OSCC, p21 expression correlates with p-S6 levels, a surrogate marker of mTOR activation, independently of p53 status.

CONCLUSION

Expression of both p21 and p-S6 was found to inversely associate with tumor size but not survival outcomes in patients with OSCC.

TRIM59 is a novel potential prognostic biomarker in patients with non-small cell lung cancer: A research based on bioinformatics analysis

Lung cancer is the leading cause of cancer-associated mortality worldwide and its prognosis is poor. Few effective biomarkers for non-small cell lung cancer (NSCLC) have been translated into the clinical practice aiming to assist in the treatment plan design and prognosis evaluation. The aim of the present study was to identify novel potential prognostic biomarkers for NSCLC. Tripartite motif 59 (TRIM59) was identified from a microarray dataset of matched-samples and was verified as an aberrantly upregulated gene in NSCLC tissue. The expression level of TRIM59 in NSCLC subtypes was observed to be significantly increased in large cell lung carcinoma and squamous cell carcinoma as compared with that in adenocarcinoma. Its expression correlated with several clinicopathological features, including gender, smoking habits, and unfavorable tumor node and pathological stages. Notably, TRIM59 demonstrated a negative correlation with survival time and its overexpression indicated a poor prognosis in NSCLC. Furthermore, univariate and multivariate Cox's regression analyses indicated that TRIM59 was an independent prognostic factor in tumor tissue as compared with age, gender, tumor stage, node stage, and metastasis. Gene set enrichment analysis and protein-protein interaction network construction revealed that TRIM59 was associated with oncogenic mammalian target of rapamycin (MTOR) and eukaryotic initiation factor 4E (EIF4E) signaling through ubiquitin C binding. In conclusion, it was revealed that TRIM59 is a novel prognostic biomarker modulating oncogenic MTOR and EIF4E signaling pathways in NSCLC. These findings provided a novel insight into the clinical application of TRIM59. Therefore, TRIM59 may serve as an independent predictor for prognosis and a potential therapeutic target for NSCLC.

In silico evaluation of DNA Damage Inducible Transcript 4 gene (DDIT4) as prognostic biomarker in several malignancies

DDIT4 gene encodes a protein whose main action is to inhibit mTOR under stress conditions whilst several in vitro studies indicate that its expression favors cancer progression. We have previously described that DDIT4 expression is an independent prognostic factor for tripe negative breast cancer resistant to neoadjuvant chemotherapy. We herein report that high DDIT4 expression is related to the outcome (recurrence-free survival, time to progression and overall survival) in several cancer types. We performed in silico analysis in online platforms, in pooled datasets from KM Plotter and meta-analysis of individual datasets from SurvExpress. High levels of DDIT4 were significantly associated with a worse prognosis in acute myeloid leukemia, breast cancer, glioblastoma multiforme, colon, skin and lung cancer. Conversely, a high DDIT4 expression was associated with an improved prognostic in gastric cancer. DDIT4 was not associated with the outcome of ovarian cancers. Analysis with data from the Cell Miner Tool in 60 cancer cell lines indicated that although rapamycin activity was correlated with levels of MTOR, it is not influenced by DDIT4 expression. In summary, DDIT4 might serve as a novel prognostic biomarker in several malignancies. DDIT4 activity could be responsible for resistance to mTOR inhibitors and is a potential candidate for the development of targeted therapy.

P-mTOR Expression and Implication in Breast Carcinoma: A Systematic Review and Meta-Analysis

Objective

Phosphorylated mammalian target of rapamycin (p-mTOR) is a promising prognostic marker in many types of cancer. However, its survival benefit in patients with breast carcinoma remains unknown. The aim of the present study was to assess the relationship between p-mTOR expression and prognosis in breast carcinoma based on a systematic review and meta-analysis.

Materials and Methods

Electronic databases (including Pubmed, Embase, ISI web of science, and Cochrane Library) were searched up to November 24, 2015. The outcome measures were hazard ratios (HRs) with 95% confidence interval (CI) for the association between the prognosis of breast carcinoma patients and p-mTOR expression. Primary end points were disease-free survival (DFS), overall survival (OS), and recurrence-free survival (RFS). Statistical analysis was performed with STATA 12.0.

Results

Nine cohort studies including 3051 patients met full eligibility criteria. The pooled HRs (95% CI) for OS, DFS, and RFS were 0.84 (0.27–2.63), 0.71 (0.40–1.23), and 0.48 (0.20–1.18), respectively.

Conclusions

Our findings suggested that p-mTOR overexpression was not significantly related to prognosis in breast carcinoma regarding OS and disease recurrence. Prospective studies are warranted to examine the association between p-mTOR expression and survival outcomes in breast carcinoma.

Phosphorylated Mammalian Target of Rapamycin p-mTOR Is a Favorable Prognostic Factor than mTOR in Gastric Cancer

Aims

The mammalian target of rapamycin (mTOR) and phosphorylated mTOR (p-mTOR) occurring downstream in the PI3K/Akt/mTOR pathway, are regarded as potential prognostic markers for gastric cancer (GC). However, the prognostic value of mTOR/p-mTOR expression remains controversial. In this study, we determined the expression of mTOR, p-mTOR, p70S6k, and p-p70S6K in GC, and investigated the correlation between their overexpression, clinicopathological parameters, and overall survival (OS).

Methods

The expression of mTOR, p-mTOR, p70S6k, and p-p70S6K was examined in 120 GC patients by immunohistochemistry (IHC). The association of protein expression with clinicopathological features and OS was explored. The p-mTOR expression was detected in normal, adjacent, and GC tissues using Western blot. Eligible studies retrieved from PubMed, Ovid, Web of Science and Cochrane databases, were reviewed in this meta-analysis.

Results

IHC showed that the rates of expression of the signal transduction molecules mTOR, p-mTOR, p70S6k and p-p70S6K in GC were 60.8%, 54.2%, 53.3% and 53.3%, respectively. Overexpression of mTOR and p70S6K showed no significant association with clinical variables. Expression of p-mTOR was significantly associated with differentiation (P < 0.01), depth of invasion (P < 0.01), lymph node metastasis (P = 0.04) and TNM stage (P = 0.02). Expression of p-p70S6K was associated with differentiation (P = 0.006), depth of invasion (P < 0.001), and TNM stage (P = 0.02). In survival analysis, differentiation, depth of invasion, lymph node metastasis and TNM stage were not related to OS (all P > 0.05). Furthermore, p-mTOR and p-p70S6K expression, but not mTOR and p70S6K, were tightly associated with OS of GC patients (P = 0.006 and P < 0.001, respectively). In Western blot, p-mTOR was significantly higher in GC tissues than in normal and adjacent tissues. In the present meta-analysis, mTOR overexpression showed no relationship with any clinicopathological variables. However, p-mTOR was correlated with depth of invasion, and TNM stage (all P < 0.05), and its overexpression was associated with a shorter survival time (P < 0.001).

Conclusion

The results suggest that p-mTOR is a more valuable prognostic factor than mTOR in GC.

Clinicopathological and prognostic significance of mTOR and phosphorylated mTOR expression in patients with esophageal squamous cell carcinoma: a systematic review and meta-analysis

BACKGROUND

Mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase responsible for regulating ribosomal biogenesis and protein synthesis. Dysregulation of mTOR contributes to tumorigenesis, angiogenesis, cellular growth and metastasis but its roles in esophageal squamous cell carcinoma (ESCC) are controversial. Therefore, the objective of this study is to evaluate the prognostic and clinicopathological significance of mTOR/p-mTOR expression in ESCC.

METHODS

Literature retrieval was conducted by searching PubMed, EMBASE and the Web of Science for full-text papers that met our eligibility criteria. Odds ratio (OR) and hazard ratio (HR) with 95 % confidence interval (CI) served as the appropriate summarized statistics for assessments of clinicopathological and prognostic significance, respectively. Cochrane Q-test and I²-statistic were adopted to estimate the heterogeneity level between studies. Potential publication bias was detected by Begg's test and Egger's test.

RESULTS

A total of 915 ESCC patients from nine original articles were included into this meta-analysis. The pooled analyses suggested that mTOR/p-mTOR expression was significantly correlated with the unfavorable outcomes of differentiation degree (OR: 2.63; 95 % CI: 1.71-4.05; P = 0.001), tumor invasion (OR: 1.48; 95 % CI: 1.02-2.13; P = 0.037), TNM stage (OR: 2.25; 95 % CI: 1.05-4.82; P = 0.037) and lymph node metastasis (OR: 1.82; 95 % CI: 1.06-3.11; P = 0.029), but had no significant relationship to the genders (OR: 0.81; 95 % CI: 0.50-1.32; P = 0.396). Moreover, mTOR/p-mTOR expression could independently predict the worse overall survival (HR: 2.04; 95 % CI: 1.58-2.62; P < 0.001), disease-free survival (HR: 2.39; 95 % CI: 1.64-3.49; P < 0.001) and cancer-specific survival (HR: 1.62; 95 % CI: 1.18-2.23; P = 0.003) of patients with ESCC. Such prognostic value of mTOR was not substantially altered by further subgroup analyses.

CONCLUSIONS

Positive expression of mTOR and p-mTOR was significantly associated with the unfavorable conditions on the depth of tumor invasion, TNM stage, differentiation degree and lymph node metastasis. mTOR and p-mTOR could serve as a valuable predictor for the poor prognosis of ESCC. More high-quality worldwide studies performing a multivariate analysis based on larger sample size are urgently required for further verifying and modifying our findings in the future.

Systematic analysis of mRNA expression profiles in NSCLC cell lines to screen metastasis-related genes

Lung cancer is the most prevalent cancer in humans and has the lowest survival outcomes due to its high metastatic potential. The aim of the present study was to screen for metastasis-related genes (MRGs) by investigating the differential expression genes (DEGs) identified by the mRNA expression profiles in SPC-A-1sci (highly metastatic) and SPC-A-1 (parental) cells. DEGs were screened using Genespring software. Gene Ontology and pathway enrichment analyses of these DEGs were performed. Interaction networks between the proteins encoded by the DEGs were identified using the database BioGRID and were visualized by Cytoscape. Modular analysis of the protein-protein interaction network was performed in CFinder. Among these DEGs, the expression levels of 18 genes were examined in SPC-A-1sci and SPC-A-1 cell lines with reverse transcription-quantitative polymerase chain reaction, and 10 of the 18 genes were assessed by western blotting to validate the results of the microarray. Furthermore, the role of metallothionein 1X (MT1X) in non-small cell lung cancer was explored in functional assays and 72 pairs of clinical samples in vitro. Finally, 4,838 DEGs were screened, including 798 upregulated and 4,040 downregulated genes. The significantly enriched functions included gene expression, cytosol and poly-(A) RNA binding, and the most enriched pathway was biosynthesis of antibiotics. Furthermore, MT1X was revealed to promote the migration and invasion ability in SPC-A-1sci and PC-9 lung cancer cell lines. Therefore, MT1X was identified as a candidate MRG through systematic analysis in the present microarray, which was demonstrated to offer potential reference value in screening MRGs.

Targeting the Mammalian Target of Rapamycin in Lung Cancer

Lung cancer is the leading cause of cancer death worldwide. Despite advances in its prevention and management, the prognosis of patients with lung cancer remains poor. Therefore, much attention is being given to factors that contribute to the development of this disease, the mechanisms that drive oncogenesis and tumor progression and the search for novel targets that could lead to the development of more effective treatments. One cellular pathway implicated in lung cancer development and progression is that of the mammalian target of rapamycin. Studies involving human tissues have linked lung cancer with abnormalities in this pathway. Furthermore, studies in vitro and in vivo using animal models of lung cancer reveal that targeting this pathway might represent an effective means of treating this disease. As a result, there is significant effort invested in the development of drugs targeting mammalian target of rapamycin and related pathways in the clinical setting.