CDKN2A copy number alteration in bladder cancer: Integrative analysis in patient-derived xenografts and cancer patients.

Bladder cancer (BlCa) is an extensively heterogeneous disease that leads to great variability in tumor evolution scenarios and lifelong patient surveillance, emphasizing the need for modern, minimally invasive precision medicine. Here, we explored the clinical significance of copy number alterations (CNAs) in BlCa. CNA profiling was performed in 15 patient-derived xenografts (PDXs) and validated in The Cancer Genome Atlas BlCa (TCGA-BLCA; n = 408) and Lindgren et al. (n = 143) cohorts. CDKN2A copy number loss was identified as the most frequent CNA in bladder tumors, associated with reduced CDKN2A expression, tumors of a papillary phenotype, and prolonged PDX survival. The study's screening cohort consisted of 243 BlCa patients, and CDKN2A copy number was assessed in genomic DNA and cell-free DNA (cfDNA) from 217 tumors and 189 pre-treatment serum samples, respectively. CDKN2A copy number loss was correlated with superior disease-free and progression-free survival of non-muscle-invasive BlCa (NMIBC) patients. Moreover, a higher CDKN2A index (CDKN2A/LEP ratio) in pre-treatment cfDNA was associated with advanced tumor stage and grade and short-term NMIBC progression to invasive disease, while multivariate models fitted for CDKN2A index in pre-treatment cfDNA offered superior risk stratification of T1/high-grade and EORTC high-risk patients, enhancing prediction of treatment outcome. CDKN2A copy number status could serve as a minimally invasive tool to improve risk stratification and support personalized prognosis in BlCa.

Cancer quiescence: non-coding RNAs in the spotlight.

Cancer quiescence reflects the ability of cancer cells to enter a reversible slow-cycling or mitotically dormant state and represents a powerful self-protecting mechanism preventing cancer cell 'damage' from hypoxic conditions, nutrient deprivation, immune surveillance, and (chemo)therapy. When stress conditions are restrained, and tumor microenvironment becomes beneficial, quiescent cancer cells re-enter cell cycle to facilitate tumor spread and cancer progression/metastasis. Recent studies have highlighted the dynamic role of regulatory non-coding RNAs (ncRNAs) in orchestrating cancer quiescence. The elucidation of regulatory ncRNA networks will shed light on the quiescence-proliferation equilibrium and, ultimately, pave the way for new treatment options. Herein, we have summarized the ever-growing role of ncRNAs upon cancer quiescence regulation and their impact on treatment resistance and modern cancer therapeutics.

Association of high miR-27a, miR-206, and miR-214 expression with poor patient prognosis and increased chemoresistance in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) represents the most aggressive breast cancer subtype, associated with early metastasis and recurrence as well as poor patient outcome. TNBC does not or weakly respond to hormonal or HER2-targeted therapies. Therefore, there is a strong need to identify other potential molecular targets for TNBC therapy. Micro-RNAs play important roles in the post-transcriptional regulation of gene expression. Thus, micro-RNAs, displaying an association between elevated expression and poor patient prognosis, may represent candidates for such novel tumor targets. In the present study, we evaluated the prognostic impact of miR-27a, miR-206, and miR-214 in TNBC via qPCR in tumor tissue (n=146). In univariate Cox regression analysis, elevated expression of all three analyzed micro-RNAs was significantly associated with shortened disease-free survival (hazard ratio [HR] for miR-27a: 1.85, P=0.038; miR-206: 1.83, P=0.041; miR-214: 2.06, P=0.012). In multivariable analysis, the micro-RNAs remained independent biomarkers for disease-free survival (HR for miR-27a: 1.99, P=0.033; miR-206: 2.14, P=0.018; miR-214: 2.01, P=0.026). Furthermore, our results suggest that elevated levels of these micro-RNAs are linked to enhanced resistance to chemotherapy. Based on the association of high expression levels with shortened patient survival and increased chemoresistance, miR-27a, miR-206, and miR-214 may represent novel molecular targets for TNBC.

Short term starvation potentiates the efficacy of chemotherapy in triple negative breast cancer via metabolic reprogramming.

BACKGROUND: Chemotherapy (CT) is central to the treatment of triple negative breast cancer (TNBC), but drug toxicity and resistance place strong restrictions on treatment regimes. Fasting sensitizes cancer cells to a range of chemotherapeutic agents and also ameliorates CT-associated adverse effects. However, the molecular mechanism(s) by which fasting, or short-term starvation (STS), improves the efficacy of CT is poorly characterized. METHODS: The differential responses of breast cancer or near normal cell lines to combined STS and CT were assessed by cellular viability and integrity assays (Hoechst and PI staining, MTT or H2DCFDA staining, immunofluorescence), metabolic profiling (Seahorse analysis, metabolomics), gene expression (quantitative real-time PCR) and iRNA-mediated silencing. The clinical significance of the in vitro data was evaluated by bioinformatical integration of transcriptomic data from patient data bases: The Cancer Genome Atlas (TCGA), European Genome-phenome Archive (EGA), Gene Expression Omnibus (GEO) and a TNBC cohort. We further examined the translatability of our findings in vivo by establishing a murine syngeneic orthotopic mammary tumor-bearing model. RESULTS: We provide mechanistic insights into how preconditioning with STS enhances the susceptibility of breast cancer cells to CT. We showed that combined STS and CT enhanced cell death and increased reactive oxygen species (ROS) levels, in association with higher levels of DNA damage and decreased mRNA levels for the NRF2 targets genes NQO1 and TXNRD1 in TNBC cells compared to near normal cells. ROS enhancement was associated with compromised mitochondrial respiration and changes in the metabolic profile, which have a significant clinical prognostic and predictive value. Furthermore, we validate the safety and efficacy of combined periodic hypocaloric diet and CT in a TNBC mouse model. CONCLUSIONS: Our in vitro, in vivo and clinical findings provide a robust rationale for clinical trials on the therapeutic benefit of short-term caloric restriction as an adjuvant to CT in triple breast cancer treatment.

tRNA-derived small RNA 3'U-tRFValCAC promotes tumour migration and early progression in ovarian cancer.

INTRODUCTION: Despite recent advances in epithelial ovarian cancer (EOC) management, the highly heterogenous histological/molecular tumour background and patients' treatment response obstructs personalised prognosis and therapeutics. Herein, we have studied the role and clinical utility of the novel subclass of tRNA-derived small RNA fragments emerging via 3'-trailer processing of pre-tRNAs (3'U-tRFs) in EOC. METHODS: SK-OV-3 and OVCAR-3 cells were used for in vitro study. Following transfection, cell growth and migration were assessed by CCK8 and wound healing assays, respectively. 3'U-tRFs levels were assessed by reverse transcription quantitative PCR (RT-qPCR), following 3'-end RNA polyadenylation. A screening (OVCAD, n = 100) and institutionally independent validation (TU Munich, n = 103) cohorts were employed for survival analysis using disease progression and patients' death as clinical end-points. Bootstrap analysis was performed for internal validation, and decision curve analysis was used to evaluate clinical benefit on disease prognosis. RESULTS: Following primary clinical assessment, target prediction and gene ontology analyses, the 3'U-tRFValCAC (derived from pre-tRNAValCAC) was highlighted to regulate cell proliferation and adhesion, and to correlate with inferior patients' outcome. 3'U-tRFValCAC transfection of SK-OV-3 and OVCAR-3 cells resulted in significantly increased cell growth and migration, in a dose-dependent manner. Elevated tumour 3'U-tRFValCAC levels were associated with significantly higher risk for early progression and worse survival following first-line platinum-based chemotherapy, independently of patients' clinicopathological data, chemotherapy response, and residual tumour. Interestingly, 3'U-tRFValCAC-fitted multivariate models improved risk stratification and provided superior clinical net benefit in prediction of treatment outcome compared to disease established markers. CONCLUSIONS: 3'U-tRFValCAC promotes tumour cell growth and migration and supports modern risk stratification and prognosis in EOC.

Repression of miR-146a in predicting poor treatment outcome in triple-negative breast cancer.

OBJECTIVES: In the era of precision medicine, the highly aggressive and heterogenous triple-negative breast cancer (TNBC) is still characterized by limited options to support personalized prognosis and guide therapeutic interventions. Thereafter, the aim of the present study has been the thorough evaluation of miR-146a as a novel molecular indicator of TNBC prognosis and treatment outcome, utilizing four independent TNBC cohorts. DESIGN & METHODS: miR-146a levels were clinically evaluated in our screening (n = 122) and three external validation TNBC cohorts (de Rinaldis et al. 2013, n = 114; Jézéquel et al. 2015, n = 107; TCGA, n = 180). Analysis of miR-146a and validated gene targets was performed in Jézéquel et al. and TCGA validation cohorts. Patients' survival, recurrence and metastasis were determined as clinical endpoints for the survival analysis. Internal validation was performed by bootstrap analysis and clinical net benefit was evaluated by decision curve analysis. RESULTS: Reduction of miR-146a is strongly associated with patients' poor survival and can predict post-treatment disease early-recurrence, independently of tumor size, lymph node status, histological grade and patients' age. The analysis of the external validation cohorts corroborated the unfavorable nature of miR-146a repression regarding patients' survival and, strikingly, unveiled the ability of miR-146a to predict TNBC metastasis. Combined assessment of miR-146a levels and lymph node status resulted in superior risk-stratification of TNBC patients and higher clinical benefit regarding disease prognosis and post-treatment outcome. Ultimately, miR-146a was negatively associated with EGFR and SOX2 expression in TNBC. CONCLUSIONS: miR-146a evaluation could ameliorate personalized prognosis and support precision medicine decisions in TNBC.

Epi-miRNAs: Modern mediators of methylation status in human cancers.

Methylation of the fundamental macromolecules, DNA/RNA, and proteins, is remarkably abundant, evolutionarily conserved, and functionally significant in cellular homeostasis and normal tissue/organism development. Disrupted methylation imprinting is strongly linked to loss of the physiological equilibrium and numerous human pathologies, and most importantly to carcinogenesis, tumor heterogeneity, and cancer progression. Mounting recent evidence has documented the active implication of miRNAs in the orchestration of the multicomponent cellular methylation machineries and the deregulation of methylation profile in the epigenetic, epitranscriptomic, and epiproteomic levels during cancer onset and progression. The elucidation of such regulatory networks between the miRNome and the cellular methylation machineries has led to the emergence of a novel subclass of miRNAs, namely "epi-miRNAs" or "epi-miRs." Herein, we have summarized the existing knowledge on the functional role of epi-miRs in the methylation dynamic landscape of human cancers and their clinical utility in modern cancer diagnostics and tailored therapeutics. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Epigenetic regulation of MIR145 core promoter controls miR-143/145 cluster in bladder cancer progression and treatment outcome.

Owing to its highly heterogeneous molecular landscape, bladder cancer (BlCa) is still characterized by non-personalized treatment and lifelong surveillance. Motivated by our previous findings on miR-143/145 value in disease prognosis, we have studied the underlying epigenetic regulation of the miR-143/145 cluster in BlCa. Expression and DNA methylation of miR-143/145 cluster were analyzed in our screening (n = 162) and The Cancer Genome Atlas Urothelial Bladder Carcinoma (TCGA-BLCA; n = 412) cohorts. Survival analysis was performed using tumor relapse and progression as clinical endpoints for non-muscle-invasive bladder cancer (NMIBC; TaT1), while disease progression and patients' death were used for muscle-invasive bladder cancer (MIBC; T2-T4). TCGA-BLCA served as validation cohort. Bootstrap analysis was carried out for internal validation, while decision curve analysis was used to evaluate clinical benefit. TCGA-BLCA and screening cohorts highlighted MIR145 core promoter as the pivotal, epigenetic regulatory region on cluster's expression. Lower methylation of MIR145 core promoter was associated with aggressive disease phenotype, higher risk for NMIBC short-term progression, and poor MIBC survival. MIR145 methylation-fitted multivariate models with established disease markers clearly enhanced patients' risk stratification and prediction of treatment outcome. MIR145 core promoter methylation was identified as a potent epigenetic regulator of miR-143/145 cluster, supporting modern personalized risk stratification and management in BlCa.

tRNAGlyGCC-Derived Internal Fragment (i-tRF-GlyGCC) in Ovarian Cancer Treatment Outcome and Progression.

Epithelial ovarian cancer (EOC) remains a highly-lethal gynecological malignancy, characterized by frequent recurrence, chemotherapy resistance and poor 5-year survival. Identifying novel predictive molecular markers remains an overdue challenge in the disease's clinical management. Herein, in silico analysis of TCGA-OV highlighted the tRNA-derived internal fragment (i-tRF-GlyGCC) among the most abundant tRFs in ovarian tumors, while target prediction and gene ontology (GO) enrichment analysis predicted its implication in key biological processes. Thereafter, i-tRF-GlyGCC levels were quantified in a screening EOC (n = 98) and an institutionally-independent serous ovarian cancer (SOC) validation cohort (n = 100, OVCAD multicenter study). Disease progression and patient death were used as clinical endpoints for the survival analysis. Internal validation was performed by bootstrap analysis and the clinical net benefit was estimated by decision curve analysis. The analysis highlighted the significant association of i-tRF-GlyGCC with advanced FIGO stages, suboptimal debulking and most importantly, with early progression and poor overall survival of EOC patients. The OVCAD validation cohort corroborated the unfavorable predictive value of i-tRF-GlyGCC in EOC. Ultimately, evaluation of i-tRF-GlyGCC with the established/clinically used prognostic markers offered superior patient risk-stratification and enhanced clinical benefit in EOC prognosis. In conclusion, i-tRF-GlyGCC assessment could aid towards personalized prognosis and support precision medicine decisions in EOC.

miR-181a overexpression predicts the poor treatment response and early-progression of serous ovarian cancer patients.

Ovarian cancer (OC) remains a leading cause of gynecological cancer-related death worldwide, characterized by poor 5-year survival. Molecular markers could serve as crucial tools of personalized prognosis and therapy. Herein, we present miR-181a as novel predictor of OC prognosis, using five independent OC cohorts. In particular, a screening (n = 81) and an institutionally independent validation (n = 100, OVCAD multicenter study) serous OC (SOC) cohorts were analyzed. Bagnoli et al (2016) OC179 (n = 124) to OC133 (n = 100) and TCGA (n = 489) served as external validation cohorts. Patients' survival and disease progression were assessed as clinical endpoint events. Bootstrap analysis was performed for internal validation and decision curve analysis was utilized to evaluate clinical benefit. miR-181a overexpression was unveiled as powerful and independent molecular predictor of patients' poor survival and higher risk for disease progression after debulking surgery and platinum-based chemotherapy. Analysis of the OVCAD institutionally independent cohort, as well as of Bagnoli et al. and TCGA external cohorts further confirmed the unfavorable prognostic nature of miR-181a overexpression in SOC. Strikingly, multivariate prognostic models incorporating miR-181a with established disease markers clearly improved patients' risk-stratification and offered superior clinical benefit in OC prognostication. Conclusively, miR-181a evaluation could augment prognostic accuracy and support precision medicine decisions in OC.

miR-203 is an independent molecular predictor of prognosis and treatment outcome in ovarian cancer: a multi-institutional study.

Ovarian cancer (OC) accounts for the most gynecological cancer-related deaths in developed countries. Unfortunately, the lack of both evident early symptoms and effective asymptomatic population screening results in late diagnosis and inevitably poor prognosis. Hence, it is urgent to identify novel molecular markers to support personalized prognosis. In the present study, we have analyzed the clinical significance of miR-203 in OC using two institutionally independent cohorts. miR-203 levels were quantified in a screening (n = 125) and a validation cohort (n = 100, OVCAD multicenter study). Survival analysis was performed using progression and death as clinical endpoint events. Internal validation was conducted by bootstrap analysis, and decision curve analysis was used to evaluate the clinical benefit. Increased miR-203 levels in OC patients were correlated with unfavorable prognosis and higher risk for disease progression, independently of FIGO stage, tumor grade, residual tumor after surgery, chemotherapy response and age. The analysis of the institutionally independent validation cohort (OVCAD study) clearly confirmed the shorter survival outcome of the patients overexpressing miR-203. Additionally, integration of miR-203 levels with the established disease prognostic markers led to a superior stratification of OC patients that can ameliorate prognosis and benefit patient clinical management. In this regard, miR-203 expression constitutes a novel independent molecular marker to improve patients' prognosis in OC.

Circulating exosomal miRNAs: clinical significance in human cancers.

Introduction: The identification of novel noninvasive biomarkers to ameliorate early-diagnosis, and disease prognosis, as well as to support personalized treatment and monitoring decisions is of first clinical priority for cancer patients' care. Exosomes are natural endosome-derived extracellular vesicles that have emerged as crucial mediators of intercellular communication and tumor progression. Considering that deregulated miRNA levels have been described in numerous human malignancies and that tumor-derived exosomes reflect miRNA expression of donor tumor cells, the evaluation of exosome-derived circulating miRNAs (exomiRs) may offer a new promising class of noninvasive molecular markers to improve patients' management and quality-of-life. Areas covered: In the current review we have summarized the existing knowledge on the clinical relevance of circulating exosomal miRNAs in improving cancer diagnosis and prognosis, and thus supporting personalized patients' management Expert commentary: Cancer research has highlighted the abundance of exomiRs in patients' plasma and serum samples, as well as their biomarker capabilities in the vast majority of human malignancies studied so far. Their analytical stability constitutes exomiRs ideal molecular markers to overcome numerous limitations of cancer clinical management, while future large-scale studies should unveil exomiRs translational utility in modern cancer molecular diagnostics.

Unraveling UCA1 lncRNA prognostic utility in urothelial bladder cancer.

In the era of precision oncology, bladder cancer (BlCa) is characterized by generic patient management and lack of personalized prognosis and surveillance. Herein, we have studied the clinical significance of urothelial cancer associated 1 (UCA1) lncRNA in improving patients' risk stratification and prognosis. A screening cohort of 176 BlCa patients was used for UCA1 quantification. The Hedegaard et al. (n = 476) and The Cancer Genome Atlas (TCGA) provisional (n = 413) were analyzed as validation cohorts for non-muscle-invasive bladder cancer (NMIBC) and muscle-invasive bladder cancer (MIBC), respectively. Patients' survival outcome was assessed using recurrence and progression for NMIBC or death for MIBC as clinical endpoint events. Bootstrap analysis was performed for internal validation of Cox regression analysis, whereas the clinical benefit of disease prognosis was assessed by decision curve analysis. UCA1 was significantly overexpressed in bladder tumors compared with normal urothelium, which was confirmed only in the case of NMIBC. Interestingly, reduced expression of UCA1 was correlated with muscle-invasive disease as well as with tumors of higher stage and grade. UCA1 loss was strongly associated with higher risk of short-term relapse [hazard ratio (HR) = 1.974; P = 0.032] and progression to invasive stages (HR = 3.476; P = 0.023) in NMIBC. In this regard, Hedegaard et al. and TCGA validation cohorts confirmed the unfavorable prognostic nature of UCA1 loss in BlCa. Finally, prognosis prediction models integrating UCA1 underexpression and established clinical disease markers contributed to improved stratification specificity and superior clinical benefit for NMIBC prognosis. Underexpression of UCA1 correlates with worse disease outcome in NMIBC and contributes to superior prediction of disease early relapse and progression as well as improved patient stratification specificity.

miRNA and long non-coding RNA: molecular function and clinical value in breast and ovarian cancers.

INTRODUCTION: The elucidation of tumor molecular hallmarks and the identification of novel molecular markers are of first translational priority in breast and ovarian cancer research, aiming to support personalized disease treatment and monitoring decisions. Recent high-throughput studies have revealed that ~ 80% of the genome is transcribed into RNAs without protein-coding potential, namely non-coding RNAs (ncRNAs), challenging the concept of 'junk DNA'. Undoubtedly, microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) represent the best-studied family classes, emerging as the most powerful gene-expression regulators at epigenetic, transcriptional and post-transcriptional levels. Areas covered: Cancer research has highlighted the active implication of ncRNAs, most notably of miRNAs and lncRNAs, in almost every aspect of the cancer cells' biology as well as their deregulated expression in both breast and ovarian tumors. In the present manuscript we discuss the existing knowledge regarding the involvement of miRNAs and lncRNAs in the molecular background of breast and ovarian malignancies, to highlight their clinical utility in improving disease management. Expert commentary: miRNAs and lncRNAs represent central mediators of cancer cells' phenotype, and promising molecular markers and therapeutic targets to support precision medicine in breast and ovarian cancers.

Combined Treatment With Exenatide and Cyclosporine A or Parstatin 1-26 Results in Enhanced Reduction of Infarct Size in a Rabbit Model.

Exenatide and cyclosporine A have been shown to moderately protect against myocardial reperfusion injury leading to reduction of infarct size in patients. Our objective was to investigate whether the combined treatment with exenatide (glucagon-like peptide 1 receptor agonist) and cyclosporine A or parstatin 1-26 (inhibitors of mitochondrial permeability transition pore and/or inflammation) is more beneficial than either agent alone. Rabbits underwent 40 minutes of ischemia and 120 minutes of reperfusion. Intravenous bolus administration of exenatide or cyclosporine A, 10 minutes before reperfusion, reduced infarct size by 38% (P < 0.05) and 40% (P < 0.05), and cardiac troponin I (cTnI) plasma levels by 48% (P < 0.05) and 36% (P < 0.05), respectively, compared with control. The combined administration of both agents resulted in an additive decrease of infarct size by 55% (P < 0.05) and cTnI release by 61% (P < 0.05). Also, combined treatment of exenatide and parstatin 1-26 enhanced infarct size reduction (62%, P < 0.05), compared with monotherapies (41% for parstatin 1-26, P < 0.05; 43% for exenatide, P < 0.05). In contrast, the combined administration of parstatin 1-26 and cyclosporine A canceled out the cardioprotective effects observed by monotherapies. These results suggest that, for the therapy of myocardial reperfusion injury the combined administration of exenatide and cyclosporine A or parstatin 1-26 is more effective than monotherapies and may provide advantageous clinical outcome.

TCRs genetically linked to CD28 and CD3ε do not mispair with endogenous TCR chains and mediate enhanced T cell persistence and anti-melanoma activity.

Adoptive transfer of T cells that are gene engineered to express a defined TCR represents a feasible and promising therapy for patients with tumors. However, TCR gene therapy is hindered by the transient presence and effectiveness of transferred T cells, which are anticipated to be improved by adequate T cell costimulation. In this article, we report the identification and characterization of a novel two-chain TCR linked to CD28 and CD3ε (i.e., TCR:28ε). This modified TCR demonstrates enhanced binding of peptide-MHC and mediates enhanced T cell function following stimulation with peptide compared with wild-type TCR. Surface expression of TCR:28ε depends on the transmembrane domain of CD28, whereas T cell functions depend on the intracellular domains of both CD28 and CD3ε, with IL-2 production showing dependency on CD28:LCK binding. TCR:28ε, but not wild-type TCR, induces detectable immune synapses in primary human T cells, and such immune synapses show significantly enhanced accumulation of TCR transgenes and markers of early TCR signaling, such as phosphorylated LCK and ERK. Importantly, TCR:28ε does not show signs of off-target recognition, as evidenced by lack of TCR mispairing, as well as preserved specificity. Notably, when testing TCR:28ε in immune-competent mice, we observed a drastic increase in T cell survival, which was accompanied by regression of large melanomas with limited recurrence. Our data argue that TCR transgenes that contain CD28, and, thereby, may provide T cell costimulation in an immune-suppressive environment, represent candidate receptors to treat patients with tumors.

The Polycomb group protein RING1B is overexpressed in ductal breast carcinoma and is required to sustain FAK steady state levels in breast cancer epithelial cells.

In early stages of metastasis malignant cells must acquire phenotypic changes to enhance their migratory behavior and their ability to breach the matrix surrounding tumors and blood vessel walls. Epigenetic regulation of gene expression allows the acquisition of these features that, once tumoral cells have escape from the primary tumor, can be reverted. Here we report that the expression of the Polycomb epigenetic repressor Ring1B is enhanced in tumoral cells that invade the stroma in human ductal breast carcinoma and its expression is coincident with that of Fak in these tumors. Ring1B knockdown in breast cancer cell lines revealed that Ring1B is required to sustain Fak expression in basal conditions as well as in Tgfß-treated cells. Functionally, endogenous Ring1B is required for cell migration and invasion in vitro and for in vivo invasion of the mammary fat pad by tumoral cells. Finally we identify p63 as a target of Ring1B to regulate Fak expression: Ring1B depletion results in enhanced p63 expression, which in turns represses Fak expression. Importantly, Fak downregulation upon Ring1B depletion is dependent on p63 expression. Our findings provide new insights in the biology of the breast carcinoma and open new avenues for breast cancer prognosis and therapy.