Loss Of PTEN Expression Research Articles

Prognostic significance of AKT/mTOR signaling in advanced neuroendocrine tumors treated with somatostatin analogs

Introduction:Somatostatin analogs (SSAs) are used as part of standard treatment for advanced neuroendocrine tumors (NETs). The mechanisms behind the antiproliferative action of SSAs remain largely unknown, but a connection with the mammalian target of rapamycin (mTOR) signaling pathway has been suggested. Our purpose was to evaluate the activation status of the AKT/mTOR pathway in advanced metastatic NETs and identify biomarkers of response to SSA therapy.Patients and methods:Expression of phosphatase and tensin homolog (PTEN), phosphorylated (p)-AKT(Ser473), and p-S6(Ser240/244) was evaluated using immunohistochemistry in archival paraffin samples from 23 patients. Expression levels were correlated with clinicopathological parameters and progression-free survival under treatment with SSAs.Results:A positive association between p-AKT and p-S6 expression was identified (P = 0.01) and higher expression of both markers was observed in pancreatic NETs. AKT/mTOR activation was observed without the loss of PTEN expression. Tumors showing AKT/mTOR signaling activation progressed faster when treated with SSAs: higher expression of p-AKT or p-S6 predicted a median progression-free survival of 1 month vs 26.5 months for lower expression (P = 0.02).Conclusion:Constitutive activation of the AKT/mTOR pathway was associated with shorter time-to-progression in patients undergoing treatment with SSAs. Larger case series are needed to validate whether p-AKT(Ser473) and p-S6(Ser240/244) can be used as prognostic markers of response to therapy with SSAs.

Modeling of Tumor Progression in NSCLC and Intrinsic Resistance to TKI in Loss of PTEN Expression

EGFR signaling plays a very important role in NSCLC. It activates Ras/ERK, PI3K/Akt and STAT activation pathways. These are the main pathways for cell proliferation and survival. We have developed two mathematical models to relate to the different EGFR signaling in NSCLC and normal cells in the presence or absence of EGFR and PTEN mutations. The dynamics of downstream signaling pathways vary in the disease state and activation of some factors can be indicative of drug resistance. Our simulation denotes the effect of EGFR mutations and increased expression of certain factors in NSCLC EGFR signaling on each of the three pathways where levels of pERK, pSTAT and pAkt are increased. Over activation of ERK, Akt and STAT3 which are the main cell proliferation and survival factors act as promoting factors for tumor progression in NSCLC. In case of loss of PTEN, Akt activity level is considerably increased. Our simulation results show that in the presence of erlotinib, downstream factors i.e. pAkt, pSTAT3 and pERK are inhibited. However, in case of loss of PTEN expression in the presence of erlotinib, pAkt level would not decrease which demonstrates that these cells are resistant to erlotinib.

PTEN Loss and AKT Activation in HER2-Positive Breast Carcinomas: Two Conditions not as Related as Initially Supposed

INTRODUCTION: PI3K/AKT pathway is involved in the pathogenesis of several human cancers and is known to regulate important cellular functions, such as cell proliferation and apoptosis. AKT is activated by a variety of stimuli including those determined by growth factor receptors as HER2 in a PI3K-dependent manner. PI3K activity is opposed by the action of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) that prevents the phosphorylation and activation of AKT resulting in the inhibition of cellular proliferation, suppressing tumor formation. A loss of PTEN function also activates AKT and leads to sustained proliferative PI3K/AKT signaling. Phosphorylated AKT (pAKT) and the product of PTEN are molecules that can be assessed by immunohistochemical analysis and it is expected that they are inversely correlated. AIMS: This study was conducted to determine the pAKT and PTEN immunohistochemical expression in a series of HER2-positive primary invasive breast tumors and their association with classical clinicopathologic features (histologic and nuclear tumor grade, hormone receptors expression, lymphatic vascular invasion and proliferative activity). MATERIALS AND METHODS: We selected 104 patients with HER2-positive breast carcinoma. Representative areas of the tumors were selected for tissue microarrays (TMA) construction. We reviewed the classical morphological and immunohistochemical features and we submitted the TMA sections to the immunohistochemical stain to PTEN (28H6 clone) and pAKT (LP18 clone) (Novocastra, Newcastle, UK). Associations between the variables were made by the statistical chi-square test. RESULTS: The expression of PTEN was reduced in 20/104 (19.2%) cases and was more frequent in tumors with positive AKT (p = 0.06). The group of tumors with loss of PTEN expression showed lower proliferative activity (p=0.034). No other variable was associated to PTEN. AKT was positive in 71/104 (68.3%) cases. High grade tumors showed lower AKT positivity (46% vs. 72%) (p=0,026), however, Pakt was associated with higher Ki-67 index. CONCLUSION: Our results confirm the role of AKT in cellular proliferation, however the control mechanisms of its phosphorylation by PTEN is not the most important and others molecules, probably associated to other signaling pathways, might be involved. The inactivation of PTEN described as one of the mechanisms involved in the resistance of HER2 tumors to the trastuzumab therapy, if it exists, it might be a rare event. In our cases, reduced expression of PTEN was observed in the lower proliferative cases. On the other hand, the raising in the cellular proliferation was associated with diffuse expression of PTEN, probably reflex of its activation to control cell proliferation.

MIS4-8 - Combinations of Laminin 5 with PTEN, p-EGFR, and p-AKT Define a Group with Poorer Prognosis in Patients with NSCLC

ABSTRACT Background Laminin 5 (Ln5) is an extracellular matrix protein that plays an important role in cell migration and tumor invasion. This study explored the expression of Ln5 and the role of its relationships with PTEN, phospho-EGFR (p-EGFR), and phospho-Akt (p-Akt) in the prognosis of patients with non-small-cell lung cancer (NSCLC). Methods The protein expression of Ln5, PTEN, p-EGFR, and p-Akt was assessed by immunohistochemical analysis, and their relationships to prognosis were analyzed. Results Protein expression of Ln5, p-EGFR, and p-Akt was detected in 61.2% (60 of 98), 60.2% (59 of 98), and 45.3% (43 of 95) of patients with NSCLC, respectively. The loss of PTEN expression was found in 67.7% of tumors (65/96). Ln5 expression was related to patient gender, histology, and p-Akt expression (k2 = 3.901, 4.549, and 6.985, respectively; P = 0.048, 0.033, and 0.008, respectively). Patients with positive Ln5 expression had marginally poorer survival than Ln5-negative patients (MST 56.4 m versus not reached; k2 = 3.346; P = 0.067). Overall survival was significantly different in patients with positive Ln5 expression combined with the loss of PTEN, positive p-EGFR expression, or positive p-Akt expression. Cox regression analysis showed that stage, co-expression of Ln5 and p-Akt, and PTEN were the three most independent prognostic factors for patients with NSCLC (k2 =27.906; P Conclusions The results highlight the complex relationships between extracellular matrix proteins and key signaling pathway molecules in tumorigenesis. Changes in the expression of Ln5 plus PTEN, p-EGFR, or p-Akt define a distinct subset of lung cancers. Patients with such cancers have worse survival, and need to be given an earlier treatment that impacts survival.

The impact of PTEN tumor suppressor gene on acquiring resistance to tamoxifen treatment in breast cancer patients

Tamoxifen is a standard therapeutical treatment in patients with estrogen receptor positive breast carcinoma. However, less than 50% of estrogen receptor positive breast cancers do not respond to tamoxifen treatment whereas 40% of tumors that initially respond to treatment develop resistance over time. The underlying mechanisms for tamoxifen resistance are probably multifactorial but remain largely unknown. The primary aim of this study was to investigate the impact of PTEN tumor suppressor gene on acquiring resistance to tamoxifen by analyzing loss of heterozygosity (LOH) and immunohystochemical expression of PTEN in 49 primary breast carcinomas of patients treated with tamoxifen as the only adjuvant therapy. The effect of PTEN inactivation on breast cancer progression and disease outcome was also analyzed. Reduced or completely lost PTEN expression was observed in 55.1% of samples, while 63.3% of samples displayed LOH of PTEN gene. Inactivation of PTEN immunoexpression significantly correlated with the PTEN loss of heterozygosity, suggesting LOH as the most important genetic mechanism for the reduction or complete loss of PTEN expression in primary breast carcinoma. Most importantly, LOH of PTEN and consequential reduction of its immunoexpression showed significant correlation with the recurrence of the disease. Besides, our study revealed that LOH of PTEN tumor suppressor was significantly associated with shorter disease free survival, breast cancer specific survival and overall survival. In summary, our results imply that LOH of PTEN could be used as a good prognostic characteristic for the outcome of breast cancer patients treated with tamoxifen.

Combined Phosphatase and Tensin Homolog (PTEN) Loss and Fatty Acid Synthase (FAS) Overexpression Worsens the Prognosis of Chinese Patients with Hepatocellular Carcinoma

We aimed to investigate the expression pattern of phosphatase and tensin homolog (PTEN), to evaluate the relationship between PTEN expression and clinicopathological characteristics, including fatty acid synthase (FAS) expression, and to determine the correlations of PTEN and FAS expression with survival in Chinese patients with hepatocellular carcinoma (HCC). The expression patterns of PTEN and FAS were determined using tissue microarrays and immunohistochemistry. The expression of PTEN was compared with the clinicopathological characteristics of HCC, including FAS expression. Receiver operator characteristic curves were used to calculate the clinical sensitivity and specificity of PTEN expression. Kaplan-Meier survival curves were constructed to evaluate the correlations of PTEN loss and FAS overexpression with overall survival. We found that the loss of PTEN expression occurred predominantly in the cytoplasm, while FAS was mainly localized to the cytoplasm. Cytoplasmic and total PTEN expression levels were significantly decreased in HCC compared with adjacent non-neoplastic tissue (both, p < 0.0001). Decreased cytoplasmic and total PTEN expression showed significant clinical sensitivity and specificity for HCC (both, p < 0.0001). Downregulation of PTEN in HCC relative to non-neoplastic tissue was significantly correlated with histological grade (p = 0.043 for histological grades I–II versus grade III). Loss of total PTEN was significantly correlated with FAS overexpression (p = 0.014). Loss of PTEN was also associated with poor prognosis of patients with poorly differentiated HCC (p = 0.049). Moreover, loss of PTEN combined with FAS overexpression was associated with significantly worse prognosis compared with other HCC cases (p = 0.011). Our data indicate that PTEN may serve as a potential diagnostic and prognostic marker of HCC. Upregulating PTEN expression and inhibiting FAS expression may offer a novel therapeutic approach for HCC.

DNMT1-mediated PTEN hypermethylation confers hepatic stellate cell activation and liver fibrogenesis in rats

Hepatic stellate cell (HSC) activation is an essential event during liver fibrogenesis. Phosphatase and tension homolog deleted on chromosome 10 (PTEN), a tumor suppressor, is a negative regulator of this process. PTEN promoter hypermethylation is a major epigenetic silencing mechanism in tumors. The present study aimed to investigate whether PTEN promoter methylation was involved in HSC activation and liver fibrosis. Treatment of activated HSCs with the DNA methylation inhibitor 5-aza-2′-deoxycytidine (5-azadC) decreased aberrant hypermethylation of the PTEN gene promoter and prevented the loss of PTEN expression that occurred during HSC activation. Silencing DNA methyltransferase 1 (DNMT1) gene also decreased the PTEN gene promoter methylation and upregulated the PTEN gene expression in activated HSC-T6 cells. In addition, knockdown of DNMT1 inhibited the activation of both ERK and AKT pathways in HSC-T6 cells. These results suggest that DNMT1-mediated PTEN hypermethylation caused the loss of PTEN expression, followed by the activation of the PI3K/AKT and ERK pathways, resulting in HSC activation.

Insulin growth factor receptor‐1 expression and loss of PTEN protein predict early recurrence in triple‐negative breast cancer

Insulin-like growth factor receptor-1 (IGFR-1) and its signalling axis promote tumorigenesis, metastasis, and resistance to existing forms of cancer therapy, and have become a major focus for the development of anticancer drugs. As oncological management options for triple-negative breast cancers (TNBCs) are limited, there is potential for the rapid development of novel selective anticancer agents specifically targeting components of the PTEN-phosphoinositide 3-kinase-AKT pathway, including the phosphorylated form of AKT (pAKT) and the tumour suppressor molecule PTEN. The aim of this study was to conduct immunohistochemical analyses to examine the levels of PTEN, IGFR-1 and pAKT expression in TNBCs, and determine whether these levels correlated with poor prognosis in this subset of aggressive breast cancers. Immunohistochemistry was performed on paraffin-embedded tumour tissues from a consecutive cohort of 144 female patients diagnosed with TNBC. Associations of IGFR-1, PTEN and pAKT expression with clinicopathological parameters, disease-free survival (DFS) and overall survival (OS) were evaluated. There were significant increases in IGFR-1 expression (99%) and pAKT expression (92%) with concomitant loss of PTEN expression in the majority of cases (63%). Increased IGFR-1 expression and loss of PTEN expression were associated with reduced OS and DFS, respectively. pAKT expression showed a strong correlation with basal-like expression. Combinatorial immunophenotypic analyses showed that loss of PTEN expression with concomitant IGFR-1 expression correlated with poor DFS. A high percentage of PTEN loss with overexpression of IGFR-1 and pAKT in TNBC indicates the potential of these molecules for predicting early recurrence and/or as targets in the formulation of effective alternative therapy regimens.

Molecular characterization of EGFR and EGFR-downstream pathways in triple negative breast carcinomas with basal like features.

Triple negative breast cancer with basal like features (TN-BCBL) do not benefit from hormonal and anti-HER2 therapies. As a considerable fraction of TN-BCBLs shows EGFR deregulation, EGFR-targeted therapies have been proposed as an option. The characterization of EGFR and EGFR-downstream members may therefore provide important predictive information. Based on morphological and immunophenotypic features, we identified 38 TN-BCBLs that were subsequently investigated for alterations in EGFR signaling pathways. EGFR and PTEN protein levels were studied by immunohistochemistry, EGFR gene status by FISH, EGFR, H-Ras, K-Ras, N-Ras, BRAF and PIK3CA gene mutations by direct sequencing. EGFR overexpression and loss of PTEN expression characterized the majority of TN-BCBLs (76% and 74% of patients, respectively). EGFR gene copy number gain (FISH+) was identified in 51% of analyzable patients. PIK3CA gene mutations were detected in three cases (8%), whereas EGFR, H-Ras, K-Ras, N-Ras and BRAF genes showed no mutations. Overall, out of 17 patients classified as FISH+, 12 cases (70%) showed a concomitant alteration in PI3K/PTEN pathway. These results provide evidence that the efficacy of anti-EGFR drugs in TN-BCBL patients could be impaired by frequent alterations in the PI3K/PTEN axis, and suggest that TN-BCBLs could benefit from tailored treatments against this axis.

Activation of and dependence on ataxia telangiectasia mutated kinase in PTEN-deficient tumor cells.

10553 Background: Loss of PTEN function has been widely reported to cause up-regulation of the PI3K/AKT signalling pathway resulting in increased cell growth, proliferation and survival. More recently it has been reported that PTEN null cells demonstrate genomic instability and have increased production of reactive oxygen species (ROS) and oxidative stress induced DNA damage. Ataxia Telangiectasia Mutated (ATM) is the primary response kinase, which responds to stalled DNA replication and DNA double strand breaks due to oxidative DNA damage. Methods: A metagene representing ATM activation was generated from cell line data and used to perform hierarchical clustering analysis of public DNA microarray profiling datasets of breast cancer, ovarian cancer and glioblastoma with known PTEN IHC/mutation status. Furthermore, we ask if ATM activation may be therapeutically exploited in PTEN null tumours using ATM specific siRNA and compounds in 2 PTEN isogenic cell line model systems. Results: We show that PTEN null cells have elevated levels of ROS, DNA damage and have endogenous activation of ATM, an enzyme important in responding to DNA damage resulting from oxidative stress. We hypothesised that PTEN deficient tumours may rely on ATM enzyme for survival. To investigate this we generated a 189-gene list representing ATM activation and used this to perform hierarchical clustering analysis of a breast cancer DNA microarray dataset. This list was able to significantly cluster tumours with known loss of PTEN expression (p=0.004). Furthermore, this gene list was able to segregate PTEN null/mutant tumours from PTEN wild-type tumours in 2 independent datasets of glioblastoma and ovarian cancer (p=0.015 and p=0.012). In addition, we found that inhibition of ATM using the selective inhibitor KU-55933 caused DNA damage, cell cycle arrest and apoptosis specifically in PTEN deficient cells when compared to PTEN wild-type cells. Conclusions: These observations suggest that ATM may represent a therapeutic target in PTEN deficient tumours and furthermore ATM activation may be the basis of a biomarker of PTEN status in human cancers.

Phase II study of everolimus (E) in refractory germ cell tumors (GCTs).

TPS4677 Background: GCTs represent a model for the cure of cancer. Nonetheless, a small proportion of patients (pts) develop disease recurrence. Because of insufficient results in the treatment of relapsed GCTs, evaluation of new treatments is a priority. Loss of the tumor suppressor gene PTEN (phosphatase and tensin homolog) marks the transition from intratubular germ cell neoplasias (ITGCN) to invasive GCTs. In the testis, PTEN was abundantly expressed in germ cells whereas it was virtually absent from 56% of seminomas as well as from 86% of embryonal carcinomas and virtually all teratomas. On the contrary, ITGCN intensely expressed PTEN, indicating that loss of PTEN expression is not in early event in GCTs development, but is associated with disease progression. PTEN inactivation is associated with dysregulation of PI3K/Akt pathway and increased mTOR signalling. We hypothesize that dysregulation of PI3K/Akt pathway due to PTEN inactivation in GCTs suggests that these pts could have greater benefit from mTOR inhibition. Methods: In December 2011, National Cancer Institute of Slovakia launched an one arm, two-staged phase II study aimed to evaluate the efficacy and toxicity of E in pts with refractory GCTs. The primary objective is to determine the efficacy of E in patients with refractory GCTs. Secondary objectives includes favourable response rate, time to progression and safety. The pts with radiological and/or serological proof of relapsed GCTs, who were not amenable to be cured by chemotherapy or surgery and who failed at least two platinum-based regimens or one platinum regimen in case of platinum-refractory disease or primary mediastinal non-seminomatous GCTs were eligible. All other standard inclusion and exclusion criteria for study of salvage treatment in refractory GCTs pts were applied. E will be administered at a dose of 10mg daily until progression or unacceptable toxicity. Assuming a response rate of clinical interest of ≥40%, a minimal response rate of 20%, a probability of 5% for rejecting an active drug, and a probability of 20% to further evaluate an ineffective drug, 18 pts will be enrolled into the first cohort. If &lt;4 responses will be observed, the study will be terminated, otherwise, it will be continued with a second cohort of 20 pts.

Targeting hyperactivation of the AKT survival pathway to overcome therapy resistance of melanoma brain metastases.

8526 Background: Brain metastases are a major contributor to mortality in stage IV melanoma patients. In melanoma, the RAF-MEK-ERK (MAPK) and PI3K-AKT-mTOR (AKT) signaling pathways play a major role in tumor progression and therapy resistance. On the basis of significant improvement in overall survival, the BRAF inhibitor vemurafenib recently gained FDA approval for the treatment of patients with metastatic BRAFV600E mutated melanoma. However, ongoing clinical studies suggest short-lived responses to BRAF inhibitors in melanoma brain metastases. Methods: We observed in several melanoma patients that chemotherapeutics or BRAF inhibitors yielded a significant regression of extracerebral metastases while brain metastases progressed or newly occurred. We therefore aimed at identifying factors that may contribute to treatment resistance of brain metastases. Results: Immunohistochemistry of matched brain and extracerebral melanoma metastases demonstrated an identical pattern of ERK, p-ERK and AKT staining but a different pattern of p-AKT and PTEN staining with hyperactivation of AKT and loss of PTEN expression in brain metastases. Mutation analysis revealed no difference in BRAF, NRAS or KIT mutation status in matched brain and extracerebral metastases. By contrast, in monolayer culture expression of ERK, p-ERK, AKT, p-AKT and PTEN was identical in cell lines derived from brain and extracerebral metastases. Furthermore, melanoma cells stimulated by astrocyte-conditioned medium showed hyperactivation of AKT compared to melanoma cells stimulated by fibroblast-conditioned medium. When inhibiting the MAPK and AKT signaling pathways at different levels in cells freshly isolated from melanoma brain metastases, growth inhibition and apoptosis induction was most pronounced with novel PI3K inhibitors such as BKM120 and BEZ235. Conclusions: These data suggest that 1) hyperactivation of the AKT survival pathway is brain environment-induced and relevant for the survival of melanoma cells in the brain parenchyma and that 2) inhibition of AKT signaling may be a suitable strategy to enhance and/or prolong the antitumor effect of chemotherapeutics or BRAF inhibitors in melanoma brain metastases.

PTEN assessment and PI3K/mTOR inhibitors: Importance of simultaneous assessment of MAPK pathway aberrations.

10510 Background: Loss of PTEN function increases PI3K/mTOR signaling. Preclinical data suggest that PTEN aberrations can predict sensitivity to drugs targeting the PI3K/mTOR pathway. Methods: Tumors from 461 patients with diverse cancers referred to the Clinical Center for Targeted Therapy were tested for cytoplasmic immunohistochemical expression of PTEN using the following scoring system: negative (no staining); positive (intact staining); reduced staining, with stroma serving as an internal positive control. Whenever possible, tumors were also tested for mutations in the MAPK pathway (KRAS, NRAS, and BRAF). We analyzed outcomes of patients treated with PI3K /mTOR with respect to their PTEN status. Results: Of 461 patients, 47 (10%) had negative PTEN expression, 168 (36.5%) had positive PTEN expression, and 246 (53.5%) had reduced PTEN. In tumor types with &gt;10 patients tested, negative PTEN was most frequent in uterine (10/33, 33%), renal (3/11, 27%), salivary gland (2/10, 20%), colorectal (15/82, 18%), breast (2/15, 13%), pancreatobiliary (3/24, 13%), and prostate cancers (2/19, 11%). Of 206 patients tested for MAPK (KRAS, NRAS, and BRAF) pathway mutations, patients with either negative or reduced PTEN had more MAPK mutations than patients with positive PTEN expression (72/144, 50% vs. 20/62, 32%, p=0.02). A total of 153 (33%) patients received therapies with PI3K /mTOR inhibitors and 17 (11%, 95% CI 0.07-0.17) achieved a partial response (PR). Proportions of PRs were 2/13 (15%) for PTEN negative, 3/50 (6%) for PTEN positive, and 12/90 (13%) for reduced PTEN. There was no significant difference in PR rate amongst patients with positive PTEN expression compared to patients with negative or reduced PTEN (3/50, 6% vs. 14/103, 14%; p=0.27). Conclusions: Complete loss of PTEN expression was found in 10% of patients. Positive PTEN expression was found in 36.5% of patients. PTEN status did not predict response to PI3K/mTOR inhibitors, perhaps because patients with negative and reduced PTEN expression had a higher incidence of simultaneous MAPK (KRAS, NRAS, BRAF) mutations.

Multiplex testing for driver mutations in squamous cell carcinomas of the lung.

7505 Background: While the majority of lung adenocarcinomas (ADCL) harbor an identifiable driver mutation, targeted therapies for squamous cell lung carcinomas (SQCLC) have lagged in development due to a paucity of druggable oncogenic events. Three targets, which together occur in up to 50% of SQCLC, have been recently identified (FGFR1 amplification, DDR2 mutations, PIK3CA mutations/PTEN loss). Comprehensive molecular analysis of SQCLC tumors by The Cancer Genome Atlas is ongoing, with new therapeutic targets on the horizon. Methods: We have instituted prospective, multiplex testing of SQCLC tumors (Squamous Cell Lung Cancer Mutation Analysis Program, “SQ-MAP”). Tests include FISH for FGFR1 amplification (defined as FGFR1:CEP8 ≥ 2 in &gt;10% of cells), IHC for loss of PTEN expression, and Sequenom MassARRAY for PIK3CA mutations (and others, below). We are also incorporating targeted exon sequencing (Agilent SureSelect/Ion Torrent) of a panel of over 80 lung cancer oncogenes and tumor suppressors in preparation for future studies. All tests were performed on formalin-fixed paraffin-embedded samples and with Institutional Review Board/Biospecimen Utilization Committee approval. Results: 40 SQCLC patient specimens have been processed through SQ-MAP over 3 months. 8 samples were excluded (insufficient tissue in 4, reclassification to ADCL in 4). Data are available for 28 patients. PTEN IHC was performed on 15 samples to date. Molecular results are summarized in the table. Events were non-overlapping. Results for the ≥80 gene sequencing component will be described. Based on SQ-MAP, accrual to 2 approved clinical trials (FGFR1 inhibition; PI3K inhibition) has begun, with a third planned (DDR2 mutations). Conclusions: Actionable defects were detected in 60% (95% CI: 37-75%) of SQCLC specimens. Mutation data for ≥80 other oncogenes and tumor suppressors will be available shortly (including DDR2). SQ-MAP serves as a platform supporting both personalized care and research. [Table: see text]

Loss of PTEN expression as a predictor of resistance to anti-EGFR monoclonal therapy in metastatic colorectal cancer: evidence from retrospective studies

To investigate the predictive value of loss of PTEN expression in patients with metastatic colorectal cancer (mCRC) treated with anti-EGFR monoclonal therapy. Studies were systematically identified to investigate the relationship between PTEN expression and clinical outcome in mCRC patients treated with anti-EGFR MoAbs. Clinical outcomes included objective response rate (ORR), progression-free survival (PFS) and overall survival (OS). The pooled relative risk (RR) or hazard ratio (HR) was estimated using a fixed-effects model or a random-effects model according to the heterogeneity between the studies. A total of 852 patients were included in the final meta-analysis. The rate of loss of PTEN expression was 28.4% (242/852). The overall pooled RR for ORR was 0.413 (95% confidence intervals (CI), 0.177-0.965) when patients with loss of PTEN expression were compared with those with normal PTEN expression. Anti-EGFR monoclonal therapy resulted in improved PFS (HR, 0.466; 95% CI, 0.292-0.640) and OS (HR, 0.689 [95% CI, 0.482-0.896]) in patients unselected by KRAS mutation with normal PTEN expression over loss of PTEN expression. A better prognosis, as reflected by PFS (HR, 0.344; 95% CI, 0.154-0.533) and OS (HR, 0.544; 95% CI, 0.285-0.803), was observed in wild-type KRAS patients with normal PTEN expression versus loss of expression. Loss of expression of PTEN is a potential biomarker for resistance to anti-EGFR monoclonal therapy, particularly in mCRC patients with KRAS wild type.

Combinations of laminin 5 with PTEN, p-EGFR and p-Akt define a group of distinct molecular subsets indicative of poor prognosis in patients with non-small cell lung cancer

Laminin 5 (Ln5) is an extracellular matrix protein that plays an important role in cell migration and tumor invasion. This study explored the expression of Ln5 and the role of its relationships with PTEN, phospho-EGFR (p-EGFR) and phospho-Akt (p-Akt) in the prognosis of patients with non-small cell lung cancer (NSCLC). The protein expression of Ln5, PTEN, p-EGFR and p-Akt was assessed by immunohistochemical analysis, and their relationships to prognosis were analyzed. Protein expression of Ln5, p-EGFR and p-Akt was detected in 61.2 (60/98), 60.2 (59/98) and 45.3% (43/95) of patients with NSCLC, respectively. Loss of PTEN expression was found in 67.7% of tumors (65/96). Ln5 expression was related to patient gender, histology and p-Akt expression (χ(2)=3.901, 4.549 and 6.985, respectively; P=0.048, 0.033 and 0.008, respectively). Patients with positive Ln5 expression had marginally poorer survival than Ln5-negative patients (median survival time 56.4 months vs. not reached; χ(2)=3.346; P=0.067). Overall survival was significantly different in patients with positive Ln5 expression combined with loss of PTEN, positive p-EGFR expression or positive p-Akt expression. Cox regression analysis showed that stage, co-expression of Ln5 and p-Akt, and PTEN were the three most independent prognostic factors for patients with NSCLC (χ(2)=27.906; P<0.0005). The results highlight the complex relationships between extracellular matrix proteins and key signaling pathway molecules in tumorigenesis. Changes in the expression of Ln5 plus PTEN, p-EGFR or p-Akt define a distinct subset of lung cancers. Patients with such cancers have poorer survival and require early treatment that impacts survival.

KRAS, BRAF and PIK3CA Mutations and the Loss of PTEN Expression in Chinese Patients with Colorectal Cancer

BackgroundTo investigate the frequency and relationship of the KRAS, BRAF and PIK3CA mutations and the loss of PTEN expression in Chinese patients with colorectal cancer (CRC).Methodology/Principal FindingsGenomic DNA was extracted from the formalin-fixed paraffin-embedded (FFPE) tissues of 69 patients with histologically confirmed CRC. Automated sequencing analysis was conducted to detect mutations in the KRAS (codons 12, 13, and 14), BRAF (codon 600) and PIK3CA (codons 542, 545 and 1047). PTEN protein expression was evaluated by immunohistochemistry on 3 mm FFPE tissue sections. Statistical analysis was carried out using SPSS 16.0 software. The frequency of KRAS, BRAF and PIK3CA mutations and loss of PTEN expression was 43.9% (25/57), 25.4% (15/59), 8.2% (5/61) and 47.8% (33/69), respectively. The most frequent mutation in KRAS, BRAF and PIK3CA was V14G (26.7% of all mutations), V600E (40.0% of all mutations) and V600L (40.0% of all mutations), and H1047L (80.0% of all mutations), respectivly. Six KRAS mutatant patients (24.0%) harbored BRAF mutations. BRAF and PIK3CA mutations were mutually exclusive. No significant correlation was observed between the four biomarkers and patients' characteristics.Conclusions/Significance BRAF mutation rate is much higher in this study than in other studies, and overlap a lot with KRAS mutations. Besides, the specific types of KRAS and PIK3CA mutations in Chinese patients could be quite different from that of patients in other countries. Further studies are warranted to examine their impact on prognosis and response to targeted treatment.

Sodium Iodide Symporter and Phosphatase and Tensin Homolog Deleted on Chromosome Ten Expression in Cholangiocarcinoma Analysis with Clinicopathological Parameters

Background/AimsThis study was performed to investigate the correlation of sodium iodide symporter (NIS) expression with the functionality and loss of phosphatase and tensin homolog deleted on chromosome ten (PTEN) expression in human cholangiocarcinoma (CCA).MethodsImmunohistochemistry for the expression of NIS and PTEN was performed in 60 biopsy specimens of CCA. The clinicopathological parameters were retrospectively identified from medical records. The expression pattern of NIS and loss of PTEN expression were analyzed in association with the clinicopathological characteristics, including survival.ResultsNormal biliary trees displayed NIS expression, but hepatocytes did not. NIS expression was divided into two patterns: cytoplasmic and membranous. Fifty-nine cases, all except for one case, displayed NIS expression in tumor cells. Twenty-two cases (33.3%) were mixed pattern, and 39 cases (65.05%) were cytoplasmic pattern; the pure membranous pattern was not noted. There was no association between the NIS expression pattern and clinicopathological parameters, including age, sex, differentiation grade, T stage and tumor, node, metastasis stage (p>0.05). The survival rates were similar among various NIS expression patterns. Normal hepatocytes and biliary trees exhibited PTEN expression in the nucleus and cytoplasm. CCA cells displayed nuclear staining. Thirty-six (60.0%) of 60 cases displayed a loss of PTEN expression. The loss of PTEN expression was observed in the advanced T-stage group (p=0.0036), but there was no association between the loss of PTEN expression and other clinicopathological parameters (p>0.05). No association between the loss of PTEN expression and survival was noted.ConclusionsNIS is expressed in most types of human CCA. The expression pattern suggests a role in cancer development. PTEN loss expression is common in the context of human CCA, especially in the advanced T stage.

Immunoexpression status and prognostic value of mammalian target of rapamycin and hypoxia-induced pathway members in papillary cell renal cell carcinomas

Dysregulation of the mammalian target of rapamycin and hypoxia-induced pathways has been consistently identified in clear cell renal cell carcinomas. However, experience with non-clear cell renal cell carcinoma subtypes is scant. In this study, we evaluated the immunohistochemical expression of upstream (PTEN and phosphorylated AKT) and downstream (phosphorylated S6 and 4EBP1) effectors of the mammalian target of rapamycin pathway, as well as related cell-cycle proteins (p27 and c-MYC), and a member of the hypoxia-induced pathway (HIF-1α) in 54 patients with papillary renal cell carcinoma treated by nephrectomy. PTEN was lower in tumor than in normal kidney, and loss of PTEN expression was found in 48% of the patients. In tumor tissues, phosphorylated S6, 4EBP1, and HIF-1α were higher than in normal kidney. Conversely, scores of p27 were lower in tumor than in normal kidney. Finally, scores of c-MYC and phosphorylated AKT were similar in tumor and in normal kidney. Overall mortality and cancer-specific mortality were 24% and 11%, respectively. Tumor progression was observed in 17% of the patients. None of the tested biomarkers predicted cancer-specific mortality or tumor progression. As expected, patients with high T-stage tumors had higher hazard ratios for cancer-specific mortality (hazard ratio, 6.9) and tumor progression (hazard ratio, 6.7). Patients with higher Fuhrman grades also had higher risks for cancer-specific mortality (hazard ratio, 11.4) and tumor progression (hazard ratio, 4.5). In summary, our study provides evidence of dysregulation of the mammalian target of rapamycin and hypoxia-induced pathways in papillary renal cell carcinoma. Immunohistochemistry for members of the mammalian target of rapamycin pathway and for HIF-1α lacked prognostic significance in our cohort.

Abstract 4186: An extensive microRNA-mediated network of RNA-RNA interactions regulates established oncogenic pathways in glioblastoma

Abstract By analyzing gene expression data in gliobastoma in combination with matched microRNA profiles, we have uncovered a post-transcriptional regulation layer of surprising magnitude, comprising over 248,000 microRNA -mediated interactions. These include ∼7,000 genes whose transcripts act as microRNA ‘sponges’ and 148 genes that act through alternative, non-sponge interactions. Biochemical analyses in cell lines confirmed that this network regulates established drivers of tumor initiation and subtype, including PTEN, PDGFRA, RB1, VEGFA, STAT3, and RUNX1, suggesting that these interactions mediate crosstalk between canonical oncogenic pathways. RNA silencing of 13 microRNA-mediated PTEN regulators, whose locus deletions are predictive of PTEN expression variability, was sufficient to downregulate PTEN in a 3′ UTR-dependent manner and to increase tumor-cell growth rates. Thus, this microRNA -mediated network provides a mechanistic, experimentally validated rationale for the loss of PTEN expression in a large number of glioma samples with an intact PTEN locus. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4186. doi:1538-7445.AM2012-4186