PTEN expression in non-small-cell lung cancer: evaluating its relation to tumor characteristics, allelic loss, and epigenetic alteration

Current concepts on the molecular pathology of non-small cell lung carcinoma

Recent advances in the understanding of the complex biology of non-small cell lung carcinoma (NSCLC), particularly activation of oncogenes by mutation, translocation and amplification, have provided new treatment targets for this disease, and allowed the identification of subsets of NSCLC tumors, mostly with adenocarcinoma histology, having unique molecular profiles that can predict response to targeted therapy. The identification of specific genetic and molecular targetable abnormalities using tumor tissue and cytology specimens followed by the administration of a specific inhibitor to the target, are the basis of personalized lung cancer treatment. In this new paradigm, the role of a precise pathology diagnosis of lung cancer and the proper handling of tissue and cytology samples for molecular testing is becoming increasingly important. These changes have posed multiple new challenges for pathologists to adequately integrate routine histopathology analysis and molecular testing into the clinical pathology practice for tumor diagnosis and subsequent selection of the most appropriate therapy.

NOTCH and PTEN in prostate cancer

Over the past decade, our understanding of the role that Notch-signaling has in tumorigenesis has shifted from leukemogenesis into cancers of solid tumors. Emerging data suggests that in addition to direct effects mediated through the canonical Notch pathway, Notch may participate in epithelial tumor development through regulation of pathways such as PTEN/PI3K/Akt. Prostate cancer is a disease for which PTEN gene expression is especially essential. This review will summarize a role for Notch in prostate development and cancer with an emphasis on how the Notch pathway may intersect with PTEN/PI3K/Akt and mTOR signaling.

[Pseudogene PTENP1 5'-region methylation in endometrial cancer and hyperplasias]

Genetic mutations in tumor suppressor gene PTEN are often detected in malignant human cells and these genomic changes are especially characteristic ofendometrial cancer. In our previous researches we assumed that alternative epigenetic mechanism of PTEN inactivation trough promoter methylation may exist in endometrial cancer. Moreover, PTENP1 pseudogene has recently been shown to play a role in positive regulation of PTENgene expression. Taking into account these facts, we analyzed PTEN and PTENP1 methylation status in endometrial hyperplasia and cancer. It was demonstrated that PTENgene promoter was not methylated but PTENP1 was methylated in 11 of 18 endometrial cancers and in 5 of9 endometrial hyperplasias. We can assume that PTENP1 methylation may inhibit transcription of this gene and also PTEN gene transcription trough RNA interference in accordance with ceRNA theory. Thus, aberrant suppression of PTENP1 transcription can play a role in endometrial cancer pathogenesis.

Cancer stem cells: progress and challenges in lung cancer

The identification of a subpopulation of tumor cells with stem cell-like characteristics first in hematological malignancies and later in solid tumors has emerged into a novel field of cancer research. It has been proposed that this aberrant population of cells now called "cancer stem cells" (CSCs) drives tumor initiation, progression, metastasis, recurrence, and drug resistance. CSCs have been shown to have the capacity of self-renewal and multipotency. Adopting strategies from the field of stem cell research has aided in identification, localization, and targeting of CSCs in many tumors. Despite the huge progress in other solid tumors such as brain, breast, and colon cancers no substantial advancements have been made in lung cancer. This is most likely due to the current rudimentary understanding of lung stem cell hierarchy and heterogeneous nature of lung disease. In this review, we will discuss the most recent findings related to identification of normal lung stem cells and CSCs, pathways involved in regulating the development of CSCs, and the importance of the stem cell niche in development and maintenance of CSCs. Additionally, we will examine the development and feasibility of novel CSC-targeted therapeutic strategies aimed at eradicating lung CSCs.

Relationships between PTEN gene mutations and prognosis in glioma: a meta-analysis

We conducted a meta-analysis in order to investigate the relationships between PTEN gene mutations and the prognosis in glioma. The following electronic databases were searched for relevant articles without any language restrictions: Web of Science (1945 ~ 2013), the Cochrane Library Database (Issue 12, 2013), PubMed (1966 ~ 2013), EMBASE (1980 ~ 2013), CINAHL (1982 ~ 2013), and the Chinese Biomedical Database (CBM) (1982 ~ 2013). Meta-analyses were conducted using the STATA software (Version 12.0, Stata Corporation, College Station, Texas USA). Hazard ratio (HR) with its corresponding 95 % confidence interval (95%CI) was calculated. Six independent cohort studies with a total of 357 glioma patients met our inclusion criteria. Our meta-analysis results indicated that glioma patients with PTEN gene mutations exhibited a significantly shorter overall survival (OS) than those without PTEN gene mutations (HR = 3.66, 95%CI = 2.02 ~ 5.30, P < 0.001). Ethnicity-stratified subgroup analysis demonstrated that PTEN gene mutations were closely linked to poor prognosis in glioma among Americans (HR = 3.72, 95%CI = 1.72 ~ 5.73, P < 0.001), while similar correlations were not observed among populations in Sweden, Italy, and Malaysia (all P > 0.05). Our meta-analysis provides direct and strong evidences for the speculation of PTEN gene mutations' correlation with poor prognosis of glioma patients.

Molecular pathways and therapeutic targets in lung cancer

Lung cancer is still the leading cause of cancer death worldwide. Both histologically and molecularly lung cancer is heterogeneous. This review summarizes the current knowledge of the pathways involved in the various types of lung cancer with an emphasis on the clinical implications of the increasing number of actionable molecular targets. It describes the major pathways and molecular alterations implicated in the development and progression of non-small cell lung cancer (adenocarcinoma and squamous cancer), and of small cell carcinoma, emphasizing the molecular alterations comprising the specific blueprints in each group. The approved and investigational targeted therapies as well as the immune therapies, and clinical trials exploring the variety of targeted approaches to treatment of lung cancer are the main focus of this review.

Altered Expression of PTEN and Its Major Regulator MicroRNA-21 in Pulmonary Neuroendocrine Tumors

Background

Phosphatase and tensin homolog on chromosome ten (PTEN) is one of the most frequently inactivated tumor suppressors in various tumor types. MicroRNA-21 (miR-21) may affect tumor progression by post-transcriptional repression of expression of tumor suppressors, such as PTEN. This study was conducted to evaluate the significance of PTEN expression in pulmonary neuroendocrine (NE) tumors and to analyze the relationship between PTEN and miR-21 expressions.

Methods

Expressions of PTEN and miR-21 were investigated by immunohistochemistry and real time reverse transcription-polymerase chain reaction, respectively, in 75 resected pulmonary NE tumors (23 typical carcinoids [TCs], nine atypical carcinoids [ACs], 22 large cell NE carcinomas [LCNECs], and 21 small cell lung carcinomas [SCLCs]).

Results

Loss of PTEN expression was observed in four of 23 TCs (17.4%), four of nine ACs (44.4%), 16 of 22 LCNECs (72.7%) and nine of 21 SCLCs (42.9%) (p=.025). The expression level of miR-21 was significantly higher in high-grade NE carcinomas than in carcinoid tumors (p<.001). PTEN expression was inversely correlated with miR-21 expression (p<.001).

Conclusions

This study suggests that aberrant expression of PTEN in relation to miR-21 may represent an important step in the development and progression of pulmonary NE tumors.

The regulatory roles of phosphatases in cancer

The relevance of potentially reversible post-translational modifications required for controlling cellular processes in cancer is one of the most thriving arenas of cellular and molecular biology. Any alteration in the balanced equilibrium between kinases and phosphatases may result in development and progression of various diseases, including different types of cancer, though phosphatases are relatively under-studied. Loss of phosphatases such as PTEN (phosphatase and tensin homologue deleted on chromosome 10), a known tumour suppressor, across tumour types lends credence to the development of phosphatidylinositol 3-kinase inhibitors alongside the use of phosphatase expression as a biomarker, though phase 3 trial data are lacking. In this review, we give an updated report on phosphatase dysregulation linked to organ-specific malignancies.

PIK3CA mutations frequently coexist with EGFR/KRAS mutations in non-small cell lung cancer and suggest poor prognosis in EGFR/KRAS wildtype subgroup

PURPOSE

PIK3CA gene encoding a catalytic subunit of the phosphatidylinositol-3-kinase (PI3K) is mutated and/or amplified in various neoplasia, including lung cancer. Here we investigated PIK3CA gene alterations, the expression of core components of PI3K pathway, and evaluated their clinical importance in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Oncogenic mutations/rearrangements in PIK3CA, EGFR, KRAS, HER2, BRAF, AKT1 and ALK genes were detected in tumors from 1117 patients with NSCLC. PIK3CA gene copy number was examined by fluorescent in situ hybridization and the expression of PI3K p110 subunit alpha (PI3K p110α), p-Akt, mTOR, PTEN was determined by immunohistochemistry in PIK3CA mutant cases and 108 patients without PIK3CA mutation.

RESULTS

PIK3CA mutation was found in 3.9% of squamous cell carcinoma and 2.7% of adenocarcinoma. Among 34 PIK3CA mutant cases, 17 tumors harbored concurrent EGFR mutations and 4 had KRAS mutations. PIK3CA mutation was significantly associated with high expression of PI3K p110α (p<0.0001), p-Akt (p = 0.024) and mTOR (p = 0.001), but not correlated with PIK3CA amplification (p = 0.463). Patients with single PIK3CA mutation had shorter overall survival than those with PIK3CA-EGFR/KRAS co-mutation or wildtype PIK3CA (p = 0.004). A significantly worse survival was also found in patients with PIK3CA mutations than those without PIK3CA mutations in the EGFR/KRAS wildtype subgroup (p = 0.043).

CONCLUSIONS

PIK3CA mutations frequently coexist with EGFR/KRAS mutations. The poor prognosis of patients with single PIK3CA mutation in NSCLC and the prognostic value of PIK3CA mutation in EGFR/KRAS wildtype subgroup suggest the distinct mutation status of PIK3CA gene should be determined for individual therapeutic strategies in NSCLC.

Alterations of INPP4B, PIK3CA and pAkt of the PI3K pathway are associated with squamous cell carcinoma of the lung

The aim of the study was to investigate how alterations in the PI3K pathway correlate with non-small cell lung cancer subtypes squamous cell carcinoma (SSC) and adenocarcinoma (ADCA). We analyzed copy number variation and protein expression of INPP4B, protein expression of pAkt, PDPK1, and PTEN and mutational status of PIK3CA and PTEN in 180 cases. Nineteen% displayed loss of INPP4B copy, whereas 47% lacked expression, both showing correlation with SCC. Elevated pAkt expression was seen in 63% of all cases, also correlating to SCC. PDPK1 was expressed in 70%, more in male than female patients. Regarding PTEN, 50% displayed loss of expression, of which seven were identified with mutations in the phosphatase domain. We detected nine cases (5%) of PIK3CA mutations, all identified as the E545K hot spot mutation in the helical domain, all except one in SCC. When analyzing all PI3K pathway components together, we show that patients with at least one alteration in the PI3K pathway are twice as likely to have SCC, than ADCA. Interestingly, we also found a strong correlation between high pAkt expression and PTEN expression. As comparison, we also analyzed mitogen-activated protein kinase (MAPK) pathway genes, where we identified fifteen KRAS mutations (8%) and one BRAF mutation (1%), significantly associated to ADCA. No association was found to the Gly972Arg polymorphism of IRS-1, involved in activation of both PI3K and MAPK pathways. In conclusion, we show here that several components of the PI3K pathway, alone and in combination, are correlated to development of SCC of the lung.

PGE2-driven expression of c-Myc and oncomiR-17-92 contributes to apoptosis resistance in NSCLC

Aberrant expression of microRNAs (miRNA) with oncogenic capacities (oncomiRs) has been described for several different malignancies. The first identified oncomiR, miR-17-92, is frequently overexpressed in a variety of cancers and its targets include the tumor suppressor PTEN. The transcription factor c-Myc (MYC) plays a central role in proliferative control and is rapidly upregulated upon mitogenic stimulation. Expression of c-Myc is frequently deregulated in tumors, facilitating proliferation and inhibiting terminal differentiation. The c-Myc-regulated network comprises a large number of transcripts, including those encoding miRNAs. Here, prostaglandin E2 (PGE2) exposure rapidly upregulates the expression of the MYC gene followed by the elevation of miR-17-92 levels, which in turn suppresses PTEN expression, thus enhancing apoptosis resistance in non-small cell lung cancer (NSCLC) cells. Knockdown of MYC expression or the miR-17-92 cluster effectively reverses this outcome. Similarly, miR-17-92 levels are significantly elevated in NSCLC cells ectopically expressing COX-2. Importantly, circulating miR-17-92 was elevated in the blood of patients with lung cancer as compared with subjects at risk for developing lung cancer. Furthermore, in patients treated with celecoxib, miR-17-92 levels were significantly reduced. These data demonstrate that PGE2, abundantly produced by NSCLC and inflammatory cells in the tumor microenvironment, is able to stimulate cell proliferation and promote resistance to pharmacologically induced apoptosis in a c-Myc and miR-17-92-dependent manner.

IMPLICATIONS

This study describes a novel mechanism, involving c-Myc and miR-17-92, which integrates cell proliferation and apoptosis resistance.

The evolving genomic classification of lung cancer

EGFR gene mutations and ALK gene fusions are well-characterized molecular targets in NSCLC. Activating alterations in a variety of potential oncogenic driver genes have also been identified in NSCLC, including ROS1, RET, MET, HER2, and BRAF. Together with EGFR and ALK, these mutations account for ∼20% of NSCLCs. The identification of these oncogenic drivers has led to the design of rationally targeted therapies that have produced superior clinical outcomes in tumours harbouring these mutations. Many patients, however, have de novo or acquired resistance to these therapies. In addition, most NSCLCs are genetically complex tumours harbouring multiple potential activating events. For these patients, disease subsets are likely to be defined by combination strategies involving a number of targeted agents. These targets include FGFR1, PTEN, MET, MEK, PD-1/PD-L1, and NaPi2b. In light of the myriad new biomarkers and targeted agents, multiplex testing strategies will be invaluable in identifying the appropriate patients for each therapy and enabling targeted agents to be channelled to the patients most likely to gain benefit. The challenge now is how best to interpret the results of these genomic tests, in the context of other clinical data, to optimize treatment choices in NSCLC.

Targeted therapies in development for non-small cell lung cancer

The iterative discovery in various malignancies during the past decades that a number of aberrant tumorigenic processes and signal transduction pathways are mediated by "druggable" protein kinases has led to a revolutionary change in drug development. In non-small cell lung cancer (NSCLC), the ErbB family of receptors (e.g., EGFR [epidermal growth factor receptor], HER2 [human epidermal growth factor receptor 2]), RAS (rat sarcoma gene), BRAF (v-raf murine sarcoma viral oncogene homolog B1), MAPK (mitogen-activated protein kinase) c-MET (c-mesenchymal-epithelial transition), FGFR (fibroblast growth factor receptor), DDR2 (discoidin domain receptor 2), PIK3CA (phosphatidylinositol-4,5-bisphosphate3-kinase, catalytic subunit alpha)), PTEN (phosphatase and tensin homolog), AKT (protein kinase B), ALK (anaplastic lym phoma kinase), RET (rearranged during transfection), ROS1 (reactive oxygen species 1) and EPH (erythropoietin-producing hepatoma) are key targets of various agents currently in clinical development. These oncogenic targets exert their selective growth advantage through various intercommunicating pathways, such as through RAS/RAF/MEK, phosphoinositide 3-kinase/AKT/mammalian target of rapamycin and SRC-signal transduction and transcription signaling. The recent clinical studies, EGFR tyrosine kinase inhibitors and crizotinib were considered as strongly effective targeted therapies in metastatic NSCLC. Currently, five molecular targeted agents were approved for treatment of advanced NSCLC: Gefitinib, erlotinib and afatinib for positive EGFR mutation, crizotinib for positive echinoderm microtubule-associated protein-like 4 (EML4)-ALK translocation and bevacizumab. Moreover, oncogenic mutant proteins are subject to regulation by protein trafficking pathways, specifically through the heat shock protein 90 system. Drug combinations affecting various nodes in these signaling and intracellular processes are predicted and demonstrated to be synergistic and advantageous in overcoming treatment resistance compared with monotherapy approaches. Understanding the role of the tumor microenvironment in the development and maintenance of the malignant phenotype provided additional therapeutic approaches as well. More recently, improved knowledge on tumor immunology has set the stage for promising immunotherapies in NSCLC. This review will focus on the rationale for the development of targeted therapies in NSCLC and the various strategies employed in preventing or overcoming the inevitable occurrence of treatment resistance.

Identification of a subset of human non-small cell lung cancer patients with high PI3Kβ and low PTEN expression, more prevalent in squamous cell carcinoma

PURPOSE

The phosphoinositide 3-kinase (PI3K) pathway is a major oncogenic signaling pathway and an attractive target for therapeutic intervention. Signaling through the PI3K pathway is moderated by the tumor suppressor PTEN, which is deficient or mutated in many human cancers. Molecular characterization of the PI3K signaling network has not been well defined in lung cancer; in particular, the role of PI3Kβ and its relation to PTEN in non-small cell lung cancer NSCLC remain unclear.

EXPERIMENTAL DESIGN

Antibodies directed against PI3Kβ and PTEN were validated and used to examine, by immunohistochemistry, expression in 240 NSCLC resection tissues [tissue microarray (TMA) set 1]. Preliminary observations were extended to an independent set of tissues (TMA set 2) comprising 820 NSCLC patient samples analyzed in a separate laboratory applying the same validated antibodies and staining protocols. The staining intensities for PI3Kβ and PTEN were explored and colocalization of these markers in individual tumor cores were correlated.

RESULTS

PI3Kβ expression was elevated significantly in squamous cell carcinomas (SCC) compared with adenocarcinomas. In contrast, PTEN loss was greater in SCC than in adenocarcinoma. Detailed correlative analyses of individual patient samples revealed a significantly greater proportion of SCC in TMA set 1 with higher PI3Kβ and lower PTEN expression when compared with adenocarcinoma. These findings were reinforced following independent analyses of TMA set 2.

CONCLUSIONS

We identify for the first time a subset of NSCLC more prevalent in SCC, with elevated expression of PI3Kβ accompanied by a reduction/loss of PTEN, for whom selective PI3Kβ inhibitors may be predicted to achieve greater clinical benefit.

New targets in non-small cell lung cancer

Lung cancer remains the most common cause of cancer-related death in the United States. At presentation, the majority of patients have regional or systemic metastases and therefore require systemic therapy. For years, chemotherapy was the only systemic therapy option. A major paradigm shift has occurred in recent years with the identification of driver genetic alterations in some non-small cell lung cancers (NSCLCs). It is part of current standard of care to assess epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) translocations in tumors of patients with advanced NSCLC. Drugs targeting these mutations provide significant clinical benefit and are the preferred therapeutic option in these patients. Ongoing clinical trials are assessing the clinical benefit from targeting other driver genetic alterations. Further therapeutic targets have been identified through greater understanding of the variety of molecular processes that facilitate tumor formation and progression. Some of these new therapeutic targets are heat shock proteins and targets that can allow enhanced anti-tumor immune response. It is expected that these advances will allow personalized management of NSCLC patients and move us away from approaching all NSCLC patients with the same therapeutic tools.

Dual EGFR inhibition in combination with anti-VEGF treatment: a phase I clinical trial in non-small cell lung cancer

BACKGROUND

Preclinical data indicate EGFR signals through both kinase-dependent and independent pathways and that combining a small-molecule EGFR inhibitor, EGFR antibody, and/or anti-angiogenic agent is synergistic in animal models.

METHODS

We conducted a dose-escalation, phase I study combining erlotinib, cetuximab, and bevacizumab. The subset of patients with non-small cell lung cancer (NSCLC) was analyzed for safety and response.

RESULTS

Thirty-four patients with NSCLC (median four prior therapies) received treatment on a range of dose levels. The most common treatment-related grade ≥2 adverse events were rash (n=14, 41%), hypomagnesemia (n=9, 27%), and fatigue (n=5, 15%). Seven patients (21%) achieved stable disease (SD) ≥6 months, two achieved a partial response (PR) (6%), and two achieved an unconfirmed partial response (uPR) (6%) (total=32%). We observed SD≥6 months/PR/uPR in patients who had received prior erlotinib and/or bevacizumab, those with brain metastases, smokers, and patients treated at lower dose levels. Five of 16 patients (31%) with wild-type EGFR experienced SD≥6 months or uPR. Correlation between grade of rash and rate of SD≥6 months/PR was observed (p less than 0.01).

CONCLUSION

The combination of erlotinib, cetuximab, and bevacizumab was well-tolerated and demonstrated antitumor activity in heavily pretreated patients with NSCLC.

Genetic alterations defining NSCLC subtypes and their therapeutic implications

Lung cancer is the leading cause of cancer death worldwide, accounting for more deaths than breast, prostate and colon cancer combined. While treatment decisions are determined primarily by stage, therapeutically non small cell lung cancer (NSCLC) has traditionally been treated as a single disease. However, recent findings have led to the recognition of histology and molecular subtypes as important determinants in treatment selection. Identifying the genetic differences that define these molecular and histological subtypes has the potential to impact treatment and as such is currently the focus of much research. Microarray and genomic sequencing efforts have provided unparalleled insight into the genomes of lung cancer subtypes, specifically adenocarcinoma (AC) and squamous cell carcinoma (SqCC), revealing subtype specific genomic alterations and molecular subtypes as well as differences in cell signaling pathways. In this review, we discuss the recurrent genomic alterations characteristic of AC and SqCC (including molecular subtypes), their therapeutic implications and emerging clinical practices aimed at tailoring treatments based on a tumor's molecular alterations with the hope of improving patient response and survival.

miR-205 targets PTEN and PHLPP2 to augment AKT signaling and drive malignant phenotypes in non-small cell lung cancer

AKT signaling is constitutively activated in various cancers, due in large part to loss-of-function in the PTEN and PHLPP phosphatases that act as tumor suppressor genes. However, AKT signaling is activated widely in non-small cell lung cancers (NSCLC) where genetic alterations in PTEN or PHLPP genes are rare, suggesting an undefined mechanism(s) for their suppression. In this study, we report upregulation of the oncomir microRNA (miR)-205 in multiple subtypes of NSCLC, which directly represses PTEN and PHLPP2 expression and activates both the AKT/FOXO3a and AKT/mTOR signaling pathways. miR-205 overexpression in NSCLC cells accelerated tumor cell proliferation and promoted blood vessel formation in vitro and in vivo. Conversely, RNA interference-mediated silencing of endogenous miR-205 abrogated these effects. The malignant properties induced by miR-205 in NSCLC cells were reversed by AKT inhibitors, FOXO3a overexpression, rapamycin treatment, or restoring PHLPP2 or PTEN expression. Mechanistic investigations revealed that miR-205 overexpression was a result of NF-κB-mediated transactivation of the miR-205 gene. Taken together, our results define a major epigenetic mechanism for suppression of PTEN and PHLPP2 in NSCLC, identifying a pivotal role for miR-205 in development and progression of this widespread disease.

Genomics of squamous cell lung cancer

Approximately 30% of patients with non-small cell lung cancer have the squamous cell carcinoma (SQCC) histological subtype. Although targeted therapies have improved outcomes in patients with adenocarcinoma, no agents are currently approved specifically for use in SQCC. The Cancer Genome Atlas (TCGA) recently published the results of comprehensive genomic analyses of tumor samples from 178 patients with SQCC of the lung. In this review, we briefly discuss key molecular aberrations reported by TCGA and other investigators and their potential therapeutic implications. Carefully designed preclinical and clinical studies based on these large-scale genomic analyses are critical to improve the outcomes of patients with SQCC of lung in the near future.

Personalized therapy on the horizon for squamous cell carcinoma of the lung

Squamous cell carcinoma (SQCC) of the lung is the second-largest subtype of non-small cell lung cancer (NSCLC), causing an estimated 400,000 deaths per year worldwide. Recent developments in cancer genome sequencing technology expanded our knowledge of driver mutations, which were identified as novel candidates for targeted therapy in various cancers. Successful targeted treatments for lung adenocarcinoma, NSCLC's primary subtype, with EGFR mutation or ALK fusion are clinically available, and a clinical trial of personalized targeted therapy in patients with lung adenocarcinoma is underway by the Lung Cancer Mutation Consortium. Although there are targeted treatments for lung adenocarcinoma, no personalized therapies currently exist for SQCC. Recently, comprehensive genomic characterization of lung SQCC using massively parallel sequencing has enabled us to identify several potential driver mutations/signaling pathways. These are FGFR1 amplifications, PI3KCA mutations, PTEN mutations/deletions, PDGFRA amplifications/mutations, and DDR2 mutations. The march toward personalized therapy may have taken a step forward with the discovery of these potential biomarkers for the treatment of SQCC of the lung. This article reviewed the current knowledge of genomic landscape of lung SQCC and summarized ongoing clinical trials of targeted agents for lung SQCC. Also, we will suggest several other actionable mutations with matching drugs that should be investigated in future clinical trials for the personalized treatment of lung SQCC.

Loss of phosphatase and tensin homolog protein expression is an independent poor prognostic marker in lung adenocarcinoma

INTRODUCTION

Phosphatase and tensin homolog (PTEN) has been established as a tumor suppressor gene with an important role in regulating the phosphatidylinositol-3-kinase/AKT antiapoptotic and survival pathway. The prognostic role of PTEN in non-small-cell lung carcinoma has not been evaluated completely in the context of other molecular information.

METHODS

Tissue microarrays containing 152 resected non-small-cell lung cancer specimens were used to investigate PTEN and p53 by immunohistochemistry and PTEN by fluorescence in situ hybridization. DNA was isolated and subjected to mutational profiling using the Sequenom Oncocarta v1.0 panel. Clinicopathological features were correlated with PTEN expression, gene copy number, and mutation status.

RESULTS

PTEN staining was absent in 63 (41.4%) of the cases. Significantly more squamous cell carcinomas compared with adenocarcinomas demonstrated loss of (negative) PTEN staining (26 of 44 [59%] versus 32 of 94 [34%]; p = 0.009). PTEN gene copy deletion was present in only seven of 124 evaluable cases (5.6%); all deleted cases were immunohistochemistry negative. In univariate and multivariate (MV) analyses adjusted for sex, age, histology, and stage, loss of PTEN protein expression was associated with significantly shorter disease-free survival (MV hazard ratio: 1.78, 95% confidence interval: 1.01-3.14, p = 0.048), whereas no significant associations were seen with p53 or KRAS and epidermal growth factor receptor (EGFR) mutation status. Importantly, the prognostic value of absent PTEN staining was limited to adenocarcinomas, with MV disease-free survival hazard ratio of 2.68 (95% confidence interval: 1.35-5.32, p = 0.005), whereas no such association was seen in squamous cell carcinomas.

CONCLUSION

Absence of PTEN protein expression is an independent prognostic marker in early-stage resected lung adenocarcinoma.

Genetic variants in the PI3K/PTEN/AKT/mTOR pathway predict platinum-based chemotherapy response of advanced non-small cell lung cancers in a Chinese population

OBJECTIVE

The PI3K/PTEN/AKT/mTOR signaling pathway has been implicated in resistance to cisplatin. In the current study, we determined whether common genetic variations in this pathway are associated with platinum-based chemotherapy response and clinical outcome in advanced non-small cell lung cancer (NSCLC) patients.

METHODS

Seven common single nucleotide polymorphisms (SNPs) in core genes of this pathway were genotyped in 199 patients and analyzed for associations with chemotherapy response, progression-free survival (PFS) and overall survival (OS).

RESULTS

Logistic regression analysis revealed an association between AKT1 rs2494752 and response to treatment. Patients carrying heterozygous AG had an increased risk of disease progression after two cycles of platinum-based chemotherapy compared to those with AA genotype (Adjusted odds ratio (OR)=2.18, 95% confidence interval (CI): 1.00-4.77, which remained significant in the stratified analyses). However, log-rank test and cox regression detected no association between these polymorphisms in the PI3K pathway genes and survival in advanced NSCLC patients.

CONCLUSIONS

Our findings suggest that genetic variants in the PI3K/PTEN/AKT/mTOR pathway may predict platinum-based chemotherapy response in advanced NSCLC patients in a Chinese population.

Preclinical rationale for PI3K/Akt/mTOR pathway inhibitors as therapy for epidermal growth factor receptor inhibitor-resistant non-small-cell lung cancer

Mutations in the epidermal growth factor receptor gene (EGFR) are frequently observed in non-small-cell lung cancer (NSCLC), occurring in about 40% to 60% of never-smokers and in about 17% of patients with adenocarcinomas. EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib, have transformed therapy for patients with EGFR-mutant NSCLC and have proved superior to chemotherapy as first-line treatment for this patient group. Despite these benefits, there are currently 2 key challenges associated with EGFR inhibitor therapy for patients with NSCLC. First, only 85% to 90% of patients with the EGFR mutation derive clinical benefit from EGFR TKIs, with the remainder demonstrating innate resistance to therapy. Second, acquired resistance to EGFR TKIs inevitably occurs in patients who initially respond to therapy, with a median duration of response of about 10 months. Mutant EGFR activates various subcellular signaling cascades, including the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway, which demonstrates maintained activity in a variety of TKI-resistant cancers. Given the fundamental role of the PI3K/Akt/mTOR pathway in tumor oncogenesis, proliferation, and survival, PI3K pathway inhibitors have emerged as a possible solution to the problem of EGFR TKI resistance. However resistance to EGFR TKIs is associated with considerable heterogeneity and complexity. Preclinical experiments investigating these phenomena suggest that in some patients, PI3K inhibitors will have to be paired with other targeted agents if they are to be effective. This review discusses the preclinical data supporting PI3K/Akt/mTOR pathway inhibitor combinations in EGFR TKI-resistant NSCLC from the perspective of the various agents currently being investigated in clinical trials.

[Advanced research of mTOR and lung carcinoid tumors]

Mammalian target of rapamycin (mTOR), a main protein kinase in the phosphoinositide 3-kinase (PI3K)/AKT/mTOR signaling pathway, is an important intracellular mediator involved in multiple celluar functions including proliferation, differentiation, apoptosis, tumorigenesis, and angiogenesis. Recently, the high expression of mTOR and mTOR-related kinase have been found in neuroendocrin tumors. Therefore, mTOR pathway represents an attractive target for new anticancer therapies except surgery.

Primary lung adenocarcinoma occurring in a PTEN related syndrome (Cowden's disease): routine EGFR sequencing also highlights two rare somatic mutations S768I and V769L

Cowden's syndrome is a rare autosomal dominant disorder that has been linked to germline mutations in the phosphatase and TENsin homolog (PTEN) gene. PTEN is a tumour suppressor gene that negatively regulates the PI3K-AKT-mTOR pathway. Cowden's syndrome is a multi-system disease with increased risks for a number of malignancies but very rarely for lung cancer. A systematic follow-up chest CT scan was performed to a 42 year's old female, light smoker. It showed a 20mm opacity of the left upper pulmonary lobe. Differential diagnose with benign tumours (such as hamartoma) was carefully searched. Procedures led to the diagnosis of a primitive lung adenocarcinoma. EGFR sequencing shows two rare somatic mutations (S768I and V769L). Lack of expression of PTEN is a non-sufficient condition leads to lung cancer formation alone. Nevertheless, it increases cell oncogenic potential. PTEN lacking in non small cell lung cancer is a frequent issue. It could be an alternative mechanism of non-efficacy of EGFR-TKI in cells with a sensitizing EGFR mutation. This case report, a very rare entity: a patient with a PTEN germline mutation and a lung adenocarcinoma harbouring two concomitant rare somatic mutations of EGFR. This observation comforts PTENs role in lung oncogenesis.

Development of PI3K/AKT/mTOR pathway inhibitors and their application in personalized therapy for non-small-cell lung cancer

Lung cancer is a common disease with more than 1.6 million new cases diagnosed worldwide in 2008. Treatments for patients with advanced disease are rarely curative, and responses to therapy are often followed by relapse, which highlights the large unmet need for novel therapies. Recent advances in cancer treatment have focused on personalized therapy, whereby patients are treated with agents that best target the molecular drivers of their disease. Thus, a better understanding of the pathways that drive cancer or drug resistance is of critical importance. One such example is the phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway, which is activated in many lung cancer patients and represents a target for therapy. PI3K/AKT/mTOR pathway activation has also been observed in tumors resistant to agents targeting upstream receptor tyrosine kinases. Agents that target this pathway have the potential to shut down survival pathways, and are being explored both in the setting of pathway-activating mutations and for their ability to restore sensitivity to upstream signaling targeted agents. Here, we examine the frequency of mutations activating the PI3K/AKT/mTOR pathway, review the novel agents being explored to target this pathway, and explore the potential role of the inhibition of this pathway in the clinical development of these agents.

Synergistic effect of olaparib with combination of cisplatin on PTEN-deficient lung cancer cells

PARP enzyme plays a key role in the cellular machinery responsible for DNA damage repair. PTEN is a tumor-suppressor gene deactivating PI3K downstream of EGFR signaling. We hypothesize that PTEN-deficient lung cancer cells suppressed DNA damage signaling and that the absence of PTEN can sensitize these cells to a concurrent treatment of a DNA-damaging agent (cisplatin) and a PARP inhibitor (olaparib). To investigate the effect of olaparib and cisplatin on PTEN-deficient lung tumors, two EGFR-mutant (deletion in exon19) non-small cell lung cancer (NSCLC) cell lines, PC-9 (PTEN wild-type) and H1650 (PTEN loss), were used. We transfected intact PTEN gene into H1650 cells (H1650(PTEN+)) and knocked down PTEN expression in the PC-9 cells (PC-9(PTEN-)) using short hairpin RNA (shRNA). Combination of cisplatin with olaparib showed a synergistic effect in vitro according to the combination index in H1650 cells. Restoration of PTEN in the H1650 cells decreased sensitivity to the combination. Ablation of PTEN in PC-9 cells increased sensitivity to olaparib and cisplatin. We also examined the effectiveness of cisplatin and olaparib in a xenograft model using H1650 and PC-9(PTEN-) cells. The combination of cisplatin with olaparib was more effective than each agent individually. This effect was not observed in a xenograft model using H1650(PTEN+) and PC-9 cells. Mechanistic investigations revealed that PTEN deficiency caused reductions in nuclear RAD51 and RPA focus formation and phosphorylated Chk1 and Mre11. Thus, genetic inactivation of PTEN led to the suppression of DNA repair.

Adeno-associated virus vector mediated expression of an oncogenic retroviral envelope protein induces lung adenocarcinomas in immunocompetent mice

Lung cancer is the most common cause of cancer-related death worldwide. A poor overall survival rate of 16% necessitates the need for novel treatment strategies. Mouse models of lung cancer are important tools for analyzing the significance of somatic mutations in the initiation and progression of lung cancer. Of additional importance, however, are animal models of virally induced cancers. JSRV is a simple betaretrovirus that causes contagious lung cancer in sheep known as ovine pulmonary adenocarcinoma and closely resembles human lung adenocarcinoma. Previously we showed that expression of the JSRV envelope (Env) from an AAV vector induced lung tumors in immunodeficient mice, but not in immunocompetent mice. Because of the importance of studying lung cancer in the context of an intact immune system we sought to improve our mouse model. In this report, we employed the use of a strong JSRV enhancer-promoter combination to express Env at high levels and demonstrate for the first time, lung tumor induction in immunocompetent mice. This occurred despite a robust Env-specific antibody-mediated immune response. The PI3K/Akt and MAPK pathways were activated in both immunocompetent and immunodeficient mice, however, differential activation of PTEN, GSKα, p70S6K, p38MAPK, ATF2 and STAT5 was observed. A JSRV Env lung tumor-derived cell line was shown to have a similar signal transduction activation profile as Env-induced lung tumors in C57BL/6 mice. Given the similarities between our model and pulmonary adenocarcinomas in humans, and the ease with which tumors can be induced in any transgenic mouse, this system can be used to uncover novel mechanisms involved lung tumorigenesis.

Anticancer role of MUC1 aptamer-miR-29b chimera in epithelial ovarian carcinoma cells through regulation of PTEN methylation

Ovarian cancer has a poor prognosis and advanced ovarian cancer lacks effective therapy. In this study, we seek to establish targeting therapy for ovarian cancer through tumor tissue-specific delivery of miRNA-29b to reexpress PTEN tumor-suppressor gene. A chimera (Chi-29b) was constructed to compose of a mucin 1 (MUC1) aptamer targeting tumor cell surface MUC1 protein and miR-29b inhibiting DNA methyltransferases' expression, subsequently reexpressing PTEN gene. The specificity and efficacy of the chimera delivery were analyzed in OVCAR-3 ovarian tumor cells, and the biological activities of the chimera were identified by the expression of its downstream molecules and cell apoptosis. We demonstrated that Chi-29b chimera can be specifically delivered into OVCAR-3 cells in a concentration-dependent manner. Dicer efficiently cleaved the Chi-29b chimera to release miR-29b. Chi-29b chimera downregulated Dnmt1, Dnmt3a, and Dnmt3b protein levels; induced hypomethylation in PTEN promoter; and upregulated PTEN mRNA and protein expression in OVCAR-3 cells. Importantly, Chi-29b chimera significantly induced apoptosis in OVCAR-3 cells. Our study indicated that Chi-29b chimera can effectively exert antitumor effect through specific delivery of miR-29b into OVCAR-3 tumor cells, subsequently reexpressing PTEN gene and inducing cell apoptosis.

The Biological Role of PI3K Pathway in Lung Cancer

Lung cancer is the primary cause of cancer-related mortality worldwide and although improvements in treatment have been achieved over the last few years, long-term survival rates for lung cancer patients remain poor. Therefore, there is an imperative need for molecularly targeted agents that will achieve long-term disease control. Numerous downstream molecular pathways, such as EGF/RAS/RAF/MEK/ERK and PI3K/AKT/mTOR are identified as having a key role in the pathogenesis of various forms of human cancer, including lung cancer. PI3K/AKT/mTOR signal pathway is an important intracellular signal transduction pathway with a significant role in cell proliferation, growth, survival, vesicle trafficking, glucose transport, and cytoskeletal organization. Aberrations in many primary and secondary messenger molecules of this pathway, including mutations and amplifications, are accounted for tumor cell proliferation, inhibition of apoptosis, angiogenesis, metastasis and resistance to chemotherapy-radiotherapy. In this review article, we investigate thoroughly the biological role of PI3K pathway in lung cancer and its contribution in the development of future therapeutic strategies.

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.

Genetic changes in squamous cell lung cancer: a review

Identifying specific somatic mutations that drive tumor growth has transformed the treatment of lung cancer. For example, cancers with sensitizing epidermal growth factor receptor mutations and echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase translocations can have remarkable responses to epidermal growth factor receptor and ALK inhibitors respectively, leading to significant clinical benefit. However, effective molecularly targeted therapies have disproportionately impacted adenocarcinomas compared to squamous cell carcinomas, and never or light smokers compared to heavy smokers. Further progress in non-small-cell lung cancer will require the identification and effective targeting of molecular alterations in all subtypes of lung cancer. Here, we review the current knowledge about the molecular alterations found in squamous cell carcinoma of the lung. First, we will discuss the ongoing efforts to comprehensively assess the squamous cell carcinoma genome. We will then discuss the evidence supporting the role of specific genes in driving squamous cell carcinomas. By describing the landscape of somatic targets in squamous cell lung cancer, we hope to crystallize the current understanding of potential targets, spur development of therapies that can have clinical impact, and underscore the importance of new discoveries in this field.

Genetic and biochemical alterations in non-small cell lung cancer

Despite significant advances in the detection and treatment of lung cancer, it causes the highest number of cancer-related mortality. Recent advances in the detection of genetic alterations in patient samples along with physiologically relevant animal models has yielded a new understanding of the molecular etiology of lung cancer. This has facilitated the development of potent and specific targeted therapies, based on the genetic and biochemical alterations present in the tumor, especially non-small-cell lung cancer (NSCLC). It is now clear that heterogeneous cell signaling pathways are disrupted to promote NSCLC, including mutations in critical growth regulatory proteins (K-Ras, EGFR, B-RAF, MEK-1, HER2, MET, EML-4-ALK, KIF5B-RET, and NKX2.1) and inactivation of growth inhibitory pathways (TP53, PTEN, p16, and LKB-1). How these pathways differ between smokers and non-smokers is also important for clinical treatment strategies and development of targeted therapies. This paper describes these molecular targets in NSCLC, and describes the biological significance of each mutation and their potential to act as a therapeutic target.

Cetuximab and biomarkers in non-small-cell lung carcinoma

Cancer progression is a highly complex process that is driven by a constellation of deregulated signaling pathways and key molecular events. In non-small-cell lung cancer (NSCLC), as in several other cancer types, the epidermal growth factor receptor (EGFR) and its downstream signaling components represent a key axis that has been found not only to trigger cancer progression but also to support advanced disease leading to metastasis. Two major therapeutic approaches comprising monoclonal antibodies and small molecule tyrosine kinase inhibitors have so far been used to target this pathway, with a combination of positive, negative, and inconsequential results, as judged by patient survival indices. Since these drugs are expensive and not all patients derive benefits from taking them, it has become both pertinent and paramount to identify biomarkers that can predict not only beneficial response but also resistance. This review focuses on the chimeric monoclonal antibody, cetuximab, its application in the treatment of NSCLC, and the biomarkers that may guide its use in the clinical setting. A special emphasis is placed on the EGFR, including its structural and mechanistic attributes.

Targeting the fanconi anemia pathway to identify tailored anticancer therapeutics

The Fanconi Anemia (FA) pathway consists of proteins involved in repairing DNA damage, including interstrand cross-links (ICLs). The pathway contains an upstream multiprotein core complex that mediates the monoubiquitylation of the FANCD2 and FANCI heterodimer, and a downstream pathway that converges with a larger network of proteins with roles in homologous recombination and other DNA repair pathways. Selective killing of cancer cells with an intact FA pathway but deficient in certain other DNA repair pathways is an emerging approach to tailored cancer therapy. Inhibiting the FA pathway becomes selectively lethal when certain repair genes are defective, such as the checkpoint kinase ATM. Inhibiting the FA pathway in ATM deficient cells can be achieved with small molecule inhibitors, suggesting that new cancer therapeutics could be developed by identifying FA pathway inhibitors to treat cancers that contain defects that are synthetic lethal with FA.

A reinvestigation of somatic hypermethylation at the PTEN CpG island in cancer cell lines

Background

PTEN is an important tumour suppressor gene that is mutated in Cowden syndrome as well as various sporadic cancers. CpG island hypermethylation is another route to tumour suppressor gene inactivation, however, the literature regarding PTEN hypermethylation in cancer is controversial. Furthermore, investigation of the methylation status of the PTEN CpG island is challenging due to sequence homology with the PTEN pseudogene, PTENP1. PTEN shares a CpG island promoter with another gene known as KLLN. Here we present a thorough reinvestigation of the methylation status of the PTEN CpG island in DNA from colorectal, breast, ovarian, glioma, lung and haematological cancer cell lines.

Results

Using a range of bisulphite-based PCR assays we investigated 6 regions across the PTEN CpG island. We found that regions 1-4 were not methylated in cancer cell lines (0/36). By allelic bisulphite sequencing and pyrosequencing methylation was detected in regions 5 and 6 in colorectal, breast and haematological cancer cell lines. However, methylation detected in this region was associated with the PTENP1 promoter and not the PTEN CpG island.

Conclusions

We show that methylation of the PTEN CpG island is a rare event in cancer cell lines and that apparent methylation most likely originates from homologous regions of the PTENP1 pseudogene promoter. Future studies should utilize assays that reliably discriminate between PTEN and PTENP1 to avoid data misinterpretation.

Nongenomic Mechanisms of PTEN Regulation

A large amount of data supports the view that PTEN is a bona fide tumor suppressor gene. However, recent evidence suggests that derailment of cellular localization and expression levels of functional nonmutated PTEN is a determining force in inducing abnormal cellular and tissue outcomes. As the cellular mechanisms that regulate normal PTEN enzymatic activity resolve, it is evident that deregulation of these mechanisms can alter cellular processes and tissue architecture and ultimately lead to oncogenic transformation. Here we discuss PTEN ubiquitination, PTEN complex formation with components of the adherens junction, PTEN nuclear localization, and microRNA regulation of PTEN as essential regulatory mechanisms that determine PTEN function independent of gene mutations and epigenetic events.

Squamous cell carcinoma of the lung: molecular subtypes and therapeutic opportunities

Lung cancer is the leading cause of cancer-related deaths worldwide. Next to adenocarcinoma, squamous cell carcinoma (SCC) of the lung is the most frequent histologic subtype in non-small cell lung cancer. Encouraging new treatments (i.e., bevacizumab, EGFR tyrosine kinase inhibitors, and ALK inhibitors) have afforded benefits to patients with adenocarcinoma, but unfortunately the same is not true for SCC. However, many genomic abnormalities are present in SCC, and there is growing evidence of their biologic significance. Thus, in the short term, the molecular characterization of patients with SCC in modern profiling platforms will probably be as important as deciphering the molecular genetics of adenocarcinoma. Patients with SCC of the lung harboring specific molecular defects that are actionable (e.g., fibroblast growth factor receptor 1 amplification, discoidin domain receptor 2 mutation, and phosphoinositide 3-kinase amplification) should be enrolled in prospective clinical trials targeting such molecular defects.

Enhanced apoptosis and tumor growth suppression elicited by combination of MEK (selumetinib) and mTOR kinase inhibitors (AZD8055)

The mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase/AKT signaling pathways interact at multiple nodes in cancer, including at mTOR complexes, suggesting an increased likelihood of redundancy and innate resistance to any therapeutic effects of single pathway inhibition. In this study, we investigated the therapeutic effects of combining the MAPK extracellular signal-regulated kinase (MEK)1/2 inhibitor selumetinib (AZD6244) with the dual mTORC1 and mTORC2 inhibitor (AZD8055). Concurrent dosing in nude mouse xenograft models of human lung adenocarcinoma (non-small cell lung cancers) and colorectal carcinoma was well tolerated and produced increased antitumor efficacy relative to the respective monotherapies. Pharmacodynamic analysis documented reciprocal pathway inhibition associated with increased apoptosis and Bim expression in tumor tissue from the combination group, where key genes such as DUSP6 that are under MEK functional control were also modulated. Our work offers a strong rationale to combine selumetinib and AZD8055 in clinical trials as an attractive therapeutic strategy.

The mechanism involved in the loss of PTEN expression in NSCLC tumor cells

Loss of PTEN expression is observed in most non-small cell lung cancers (NSCLC). However, the mechanism by which PTEN expression is regulated in NSCLC has not been fully elucidated. In this study, we investigated the role of DNA methyltransferases (Dnmts), microRNA-29b (miR-29b), and anti-miR-29b inhibitor in PTEN promoter methylation and PTEN gene expression in H358 NSCLC cells in vitro and in vivo. PTEN mRNA was measured by RT-PCR. PTEN and Dnmts protein levels were measured by Western blot. miR-29b expression was detected by Northern blot. A xenograft H358 tumor mouse model was established by subcutaneously inoculating H358 cells into the right hind limbs of nude mice. We found that radiation induced cell apoptosis and hypomethylation in PTEN promoter, PTEN and miR-29b expression, and downregulation of Dnmt1, 3a and 3b expression in H358 tumor cells. The effect of radiation on gene expression and apoptosis was blocked by anti-miR-29b inhibitor. In the xenograft H358 tumor model, anti-miR-29b inhibitor reversed radiation-induced tumor growth delay, PTEN reexpression and downregulation of Dnmts expression. Our study suggested that miR-29b is an upstream molecule of PTEN. miR-29b regulates PTEN gene expression through downregulating Dnmts expression and subsequently induces hypomethylation in PTEN promoter. Targeting therapy could be established in NSCLC by upregulating miR-29b expression.

PI3K Pathway in NSCLC

The phosphatidylinositol 3-kinases (PI3Ks) are members of a family of intracellular lipid kinases that phosphorylate the 3′-hydroxyl group of phosphatidylinositol and phosphoinositides. PI3K regulate signaling pathways for neoplasia, including cell proliferation, adhesion, survival, and motility. Different classes of PI3K have distinct roles in cellular signal transduction. PI3K pathway is activated by several different mechanisms in cancers, including, somatic mutation and gene amplification. In this review, we examine the literature addressing PI3K mutation status and gene amplification, with an emphasis on non-small cell lung cancer.

Impact of HER2 and PTEN simultaneous deregulation in non-small cell lung carcinoma: correlation with biological behavior

BACKGROUND

HER2/neu overexpression due to gene amplification is an important factor in breast cancer, modifying the sensitivity to anti-HER2 monoclonal antibody therapy. The clinical significance of HER2 expression in non small cell lung carcinoma (NSCLC) is currently under evaluation. The tumor suppressor gene PTEN negatively regulates the HER2/PI3K/Akt signalling pathway. The purpose of this study was to evaluate the role of simultaneous alteration in HER2 and PTEN protein expression in relation to biological behaviour of NSCLCs.

MATERIALS AND METHOD

Protein expression was determined by immunohistochemistry in sixty-one (n=61) NSCLC cases along with CISH for HER2 gene analysis and detection of chromosome 17 aneuploidy. Patients were followed-up for a period of 34 to 41 months after surgery.

RESULTS

HER2 overexpression (2+/3+ score) was detected in 17 (27.9%) patients while loss of PTEN expression was observed in 24 (39.3%) cases, low expression in 29 (47.6%) and overexpression in 8 (13.1%). Simultaneous HER2 overexpression and PTEN low/loss of expression were correlated with metastasis (71.4% vs 36.2% p=0.03) . Analysis in the subgroup of 22 patients of pTNM stage III with lymph node status N1 or N2 revealed that there was a relationship between the number of positive regional lymph node groups and simultaneous deregulation of the two genes (p=0.04). Multivariate analysis determined that HER2 overexpression was associated with an increasing risk of developing metastases (OR: 4.3; 95%CI: 1.2-15.9; p: 0.03) while PTEN overexpression was associated with lower risk (OR: 0.1; 95%CI: 0.1, 1.0; p: 0.05).

CONCLUSIONS

Simultaneous HER2/PTEN deregulation is a significant genetic event that leads to a more aggressive phenotype of NSCLC.

Clinical implications of epigenetic alterations in human thoracic malignancies: epigenetic alterations in lung cancer

Besides known genetic aberrations, epigenetic alterations have emerged as common hallmarks of many cancer types, including lung cancer. Epigenetics is a process involved in gene regulation, mediated via DNA methylation, histone modification, chromatin remodeling, and functional noncoding RNAs, which influences the accessibility of the underlying DNA to transcriptional regulatory factors that activate or repress expression. Studies have shown that epigenetic dysregulation is associated with multiple steps during carcinogenesis. Since epigenetic therapy is now in clinical use in hematopoietic diseases and undergoing trials for lung cancer, a better understanding of epigenetic abnormalities is desired. Recent technologies for high-throughput genome-wide analyses for epigenetic modifications are promising and potent tools for understanding the global dysregulation of cancer epigenetics. In this chapter, studies of epigenetic abnormality and its clinical implication in lung cancers are discussed.

Molecular biology of lung cancer: clinical implications

Lung cancer is a heterogeneous disease clinically, biologically, histologically, and molecularly. Understanding the molecular causes of this heterogeneity, which might reflect changes occurring in different classes of epithelial cells or different molecular changes occurring in the same target lung epithelial cells, is the focus of current research. Identifying the genes and pathways involved, determining how they relate to the biological behavior of lung cancer, and their utility as diagnostic and therapeutic targets are important basic and translational research issues. This article reviews current information on the key molecular steps in lung cancer pathogenesis, their timing, and clinical implications.