Reduced Expression of PTEN Protein and Its Prognostic Implications in Invasive Ductal Carcinoma of the Breast

Comprehensive genomic evaluation of advanced and recurrent breast cancer patients for tailored precision treatments

AIM

The aim of this study was to investigate genetic alterations within breast cancer in the setting of recurrent or de novo stage IV disease.

PATIENTS AND METHODS

This study included 22 patients with recurrent breast cancer (n = 19) and inoperable de novo stage IV breast cancer (n = 3). For next generation sequencing, FoundationOneCDx (F1CDx) (Foundation Medicine Inc., Cambridge, MA, USA) was performed in 21 patients and FoundationOneLiquid CDx was performed in 1 patient.

RESULTS

Median age was 62.9 years (range, 33.4-82.1). Pathological diagnoses of specimens included invasive ductal carcinoma (n = 19), invasive lobular carcinoma (n = 2), and invasive micropapillary carcinoma (n = 1). F1CDx detected a median of 4.5 variants (range, 1-11). The most commonly altered gene were PIK3CA (n = 9), followed by TP53 (n = 7), MYC (n = 4), PTEN (n = 3), and CDH1 (n = 3). For hormone receptor-positive patients with PIK3CA mutations, hormonal treatment plus a phosphoinositide 3-kinase inhibitor was recommended as the treatment of choice. Patients in the hormone receptor-negative and no human epidermal growth factor receptor 2 expression group had significantly higher tumor mutational burden than patients in the hormone receptor-positive group. A BRCA2 reversion mutation was revealed by F1CDx in a patient with a deleterious germline BRCA2 mutation during poly ADP ribose polymerase inhibitor treatment.

CONCLUSION

Guidance on tailored precision therapy with consideration of genomic mutations was possible for some patients with information provided by F1CDx. Clinicians should consider using F1CDx at turning points in the course of the disease.

p53 and PTEN expression evaluation with molecular evident recent criteria in laryngeal carcinoma

The prognosis of laryngeal cancer is affected by clinicopathological factors. Because of that, an effective prognostic marker is very valuable in managing the clinical process. The p53 evaluation method, used in the literature recently, was used for the first time in laryngeal cancer. We evaluated PTEN with 2 methods with the highest significance in the literature on laryngeal cancer. All demographic and histopathological data from 140 laryngeal cancers were compared with p53 and PTEN expressions and survival. p53 staining patterns were classified as wild and mutant. PTEN expression was evaluated according to the staining intensity named PTEN1 and according to the proportion of stained cells named PTEN2. In the series, 93.6% were males, and the mean survival was 38 months. 69.3% of cases were p53 mutants. PTEN loss was found to be 85.7% and 57.9%, respectively. Tumor size and thyroid cartilage invasion for PTEN1 and age for p53 were identified as independent predictive factors (P < .01). Advanced age, total laryngectomy, and extranodal spread were independent poor prognostic factors for overall survival and the presence of subglottic involvement, perineural invasion, and extranodal spread were for disease-free survival (P < .01). This is the first study in which the new p53 classification was used in laryngeal cancer, and will contribute significantly to the literature with differences from the previous evaluation patterns. Evaluation of PTEN based on staining intensity is more appropriate compared to the percentage of stained cells.

PTEN Deficiency in Tubo-Ovarian High-Grade Serous Carcinoma is Associated with Poor Progression-Free Survival and is Mutually Exclusive with CCNE1 Amplification

As a critical tumor suppressor, PTEN has gained much attention in cancer research. Emerging evidence suggests an association between PTEN status and clinical outcome in certain tumors, and may be predictive of response to several therapies. However, the significance of PTEN deficiency in tubo-ovarian high-grade serous carcinomas (HGSCs) is still poorly understood. We evaluated PTEN expression in HGSCs and determined its clinical relevance. A cohort of 76 HGSC specimens was profiled using tissue microarray. Immunohistochemistry (IHC) of PTEN, ER, PR, AR, CD8, FOXP3, and PD-L1 was performed. Targeted gene panel testing by massively parallel sequencing was performed in 51 cases. PTEN deficiency (complete or subclonal loss) detected by IHC was identified in 13 of the 62 HGSCs (21%) and was significantly correlated with reduced expression of ER and worse first progression-free survival (P < .05) but not with PD-L1 expression, the density of intratumoral T lymphocytes, or overall survival. In our cohort, tumor progression within 1 year of PARP inhibitor therapy was found more frequently in PTEN-deficient cases than in PTEN-intact cases (100% vs 52%). Molecular profiling showed that intragenic mutation or deletion was not the predominant mechanism for PTEN inactivation in HGSCs. In addition, CCNE1 amplification was found to be mutually exclusive with PTEN deficiency at both protein and DNA levels. An analysis of the genomic data from 1702 HGSC samples deposited with The Cancer Genome Atlas database obtained from cBioPortal confirmed the low rate of detection of PTEN gene alterations and the mutually exclusive nature of PTEN loss and CCNE1 amplification in HGSCs. These findings indicate that PTEN deficiency defines a distinct clinically significant subgroup of HGSCs with a tendency for ER negativity, wild-type CCNE1 status, inferior clinical outcomes, and potential drug resistance. These tumors may benefit from PI3K pathway inhibitors in combination with other ovarian cancer regimens, which deserves further investigation.

Fe3O4 Nanoparticles in Combination with 5-FU Exert Antitumor Effects Superior to Those of the Active Drug in a Colon Cancer Cell Model

(1) Background: Colon cancer is one of the most common cancer types, and treatment options, unfortunately, do not continually improve the survival rate of patients. With the unprecedented development of nanotechnologies, nanomedicine has become a significant direction in cancer research. Indeed, chemotherapeutics with nanoparticles (NPs) in cancer treatment is an outstanding new treatment principle. (2) Methods: Fe3O4 NPs were synthesized and characterized. Caco-2 colon cancer cells were treated during two different periods (24 and 72 h) with Fe3O4 NPs (6 μg/mL), various concentrations of 5-FU (4−16 μg/mL), and Fe3O4 NPs in combination with 5-FU (4−16 μg/mL) (Fe3O4 NPs + 5-FU). (3) Results: The MTT assay showed that treating the cells with Fe3O4 NPs + 5-FU at 16 µg/mL for 24 or 72 h decreased cell viability and increased their LDH release (p < 0.05 and p < 0.01, respectively). Furthermore, at the same treatment concentrations, total antioxidant capacity (TAC) was decreased (p < 0.05 and p < 0.01, respectively), and total oxidant status (TOS) increased (p < 0.05 and p < 0.01, respectively). Moreover, after treatment with Fe3O4-NPs + 5-FU, the IL-10 gene was downregulated and PTEN gene expression was upregulated (p < 0.05 and p < 0.01, respectively) compared with those of the control. (4) Conclusions: Fe3O4 NPs exert a synergistic cytotoxic effect with 5-FU on Caco-2 cells at concentrations below the active drug threshold levels.

Akt Isoforms: A Family Affair in Breast Cancer

Simple Summary

Breast cancer is the second leading cause of cancer-related death in women in the United States. The Akt signaling pathway is deregulated in approximately 70% of patients with breast cancer. While targeting Akt is an effective therapeutic strategy for the treatment of breast cancer, there are several members in the Akt family that play distinct roles in breast cancer. However, the function of Akt isoforms depends on many factors. This review analyzes current progress on the isoform-specific functions of Akt isoforms in breast cancer.

Abstract

Akt, also known as protein kinase B (PKB), belongs to the AGC family of protein kinases. It acts downstream of the phosphatidylinositol 3-kinase (PI3K) and regulates diverse cellular processes, including cell proliferation, cell survival, metabolism, tumor growth and metastasis. The PI3K/Akt signaling pathway is frequently deregulated in breast cancer and plays an important role in the development and progression of breast cancer. There are three closely related members in the Akt family, namely Akt1(PKBα), Akt2(PKBβ) and Akt3(PKBγ). Although Akt isoforms share similar structures, they exhibit redundant, distinct as well as opposite functions. While the Akt signaling pathway is an important target for cancer therapy, an understanding of the isoform-specific function of Akt is critical to effectively target this pathway. However, our perception regarding how Akt isoforms contribute to the genesis and progression of breast cancer changes as we gain new knowledge. The purpose of this review article is to analyze current literatures on distinct functions of Akt isoforms in breast cancer.

Correlation Between Onco-suppressors PTEN and NM23 and Clinical Outcome in Patients With T1 Breast Cancer

BACKGROUND

The aim of the present work was to evaluate the prognostic significance in patients with T1 breast cancer of tissue expression of the two oncosuppressors phosphatase and tensin homolog (PTEN) and non-metastatic clone 23 (NM23) as detected by immunohistochemistry.

MATERIALS AND METHODS

We prospectively analyzed 62 patients who underwent surgery for a T1 stage breast cancer. Expression of PTEN and NM23 was tested for correlation with clinical characteristics and clinical outcome.

RESULTS

Of the 62 patients considered for our study, 16 underwent mastectomy and 46 underwent conservative surgical treatment. The surgery was considered radical (R0) in all cases described. PTEN and NM23 expression was higher in patients with no lymph node metastases and no recurrent cancer at a mean follow-up of 36 months (range=6-48 months). This correlation was more evident when both PTNE and NM23 expression were highly expressed (p<0.0001).

CONCLUSION

Low or lack of PTEN and NM23 immunohistochemical expression in cancer tissue is a risk factor for lymph node involvement and recurrent disease. It may represent a valid prognostic factor in planning therapy in patients who had surgery for T1 breast cancer.

An Immunohistochemical Study of the PTEN/AKT Pathway Involvement in Canine and Feline Mammary Tumors

Simple Summary

The PTEN/AKT pathway is involved in several human and animal tumors’ pathogenesis. This study investigates the PTEN/AKT pathway’s biological and prognostic values in canine and feline mammary tumors. PTEN, phospho-AKT (p-AKT) and Rictor expression was determined by immunohistochemistry in canine mammary adenomas and carcinomas and feline mammary carcinomas. In mammary tumors of both species p-Akt was inversely correlated with PTEN expression and positively with Rictor expression; p-Akt and Rictor expression correlated with poorer prognosis. This data could provide a rationale for further studies of this pathway in veterinary oncology due to prognostic and therapeutic implications.

Abstract

Phosphatase and tensin homolog deleted on chromosome10 (PTEN), phospho-v-Akt murine thymoma viral oncogene homolog (AKT), and the Rapamycin-Insensitive Companion of mTOR (Rictor) expression was investigated by immunohistochemistry in 10 canine mammary adenomas (CMAs), 40 canine mammary carcinomas (CMCs), and 30 feline mammary carcinomas (FMCs). All the CMAs, 25 of 40 CMCs (63%) and 7 of 30 FMCs (23%), were PTEN-positive. In dogs, no CMAs and 15 of 25 CMCs (37%) expressed phospho-AKT (p-AKT), while 24 of 30 FMCs (82%) were p-AKT-positive. One of 10 CMAs (10%), 24 of 40 CMCs (60%) and 20 of 30 FMCs (67%) were Rictor-positive. In the dog, PTEN expression correlated with less aggressive tumors, absence of lymphatic invasion, and longer survival. P-AKT expression correlated with more aggressive subtype, lymphatic invasion, and poorer survival and Rictor expression with lymphatic invasion. In cats, PTEN correlated with less aggressive carcinomas, absence of lymphatic invasion, and better survival. P-AKT and Rictor expression correlated with poorer survival. PTEN expression was inversely correlated with p-AKT and Rictor in both species, while p-AKT positively correlated with Rictor expression. A strong PTEN/AKT pathway involvement in behavior worsening of CMT and FMTs is demonstrated, providing a rationale for further studies of this pathway in veterinary oncology.

Prognostic value of the PIK3CA, AKT, and PTEN mutations in oral squamous cell carcinoma: literature review

Over 260,000 (2013) new oral squamous cell carcinoma (OSCC) cases are reported annually worldwide. Despite development in OSCC management, the outcome is still unsatisfactory. Identification of new molecular markers may be of use in prevention, prognosis, and choice of an appropriate therapy. The intracellular molecular signalling pathway of phosphatidyl-inositol-3-kinase is involved in the process of cell growth, differentiation, migration, and survival. The main components of this pathway: PIK3CA (phosphatidylinositol-4,5-bisphosphate-3-kinase catalytic subunit α), PTEN (phosphatase and tensin homologue deleted on chromosome 10), and AKT (serine-threonine kinase) are potential objects of research when introducing new therapeutic agents. The aim of this paper is to evaluate the PIK3CA, PTEN, and AKT gene mutations as prognostic factors in OSCC and to describe their role in aggressive disease progression. This is crucial for oral cancer biology understanding and for indicating which direction new clinical treatments should take.

Any Role of PIK3CA and PTEN Biomarkers in the Prognosis in Oral Squamous Cell Carcinoma?

Oral squamous cell carcinoma (OSCC) accounts for 95% of the lesions in the oral cavity. Despite development in OSCC management, the outcome is still unsatisfactory. Identification of new therapies in OSCC is urgently needed. One objective of such treatment may be a signaling pathway of phosphatidylinositol 3-kinase. The study group included 92 patients treated for OSCC at the University Clinical Centre in Gdańsk, Poland. Study was performed on formalin-fixed paraffin-embedded samples from primary OSCC. Phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA) and phosphatase and tensin homolog encoded on chromosome 10 (PTEN) protein expression was assessed by immunohistochemistry (IHC). PIK3CA gene copy number was analyzed using chromogenic and silver in situ hybridization where molecular probes are marked by chromogens and silver ions. PIK3CA IHC H-score ≥ 70 was found in 51.65% patients, and loss of PTEN protein was noticed in 31.46% cases. PIK3CA amplification was detected in 5 tumors. In the case of PTEN protein expression, there was an inverse correlation with the T stage of the primary tumor (r = -0.243) and positive correlation with a 5-year survival (r = 0.235). The number of copies of the PIK3CA gene was associated with the tumor grading (r = 0.208). The present study shows that loss of PTEN protein and the grading (p = 0.040), distant metastases (p = 0.033), smoking (p = 0.016), and alcohol abuse (p = 0.042) were prognostic factors for the survival of patients with OSCC. In contrast, the presence of amplification and OSCC on the floor of the mouth resulted in a nearly six-fold increase in the risk of shortening survival (p = 0.037). Our finding suggests a potential prognostic significance of PTEN loss and PIK3CA amplification in OSCC. Future studies are needed to confirm our results.

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

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

PIK3CA and PTEN Genes Expressions in Breast Cancer

Background:

The phosphatidylinositol-3 kinase (PI3K) intracellular signaling pathway plays an important role in breast cancer. The current study aimed to evaluate the expressions of two main regulators of PI3K pathway; phosphatidylinositol-3- kinase catalytic subunit alpha as activator (PIK3CA), and phosphatase and tensin-homolog as inhibitor (PTEN), in breast carcinoma tissue, and compare with their expressions in adjacent normal breast tissue.

Methods:

A total of fifty female patients with breast carcinoma from surgical oncology unit of Alexandria-Main University Hospital were included in this study. The Quantitative Real Time PCR was used to quantify expressions of PIK3CA and PTEN.

Results:

PIK3CA mRNA expression was significantly increased in breast cancer tissues compared to normal breast tissues (P<0.001, Z=5.700), also PTEN mRNA expression was significantly higher in breast carcinoma tissue compared to normal breast tissue (P<0.001, Z=5.362).

Conclusion:

Increased the expressions of PIK3CA and PTEN mRNA in breast cancer tissue compared to normal breast tissue.

BRCA1-IRIS promotes human tumor progression through PTEN blockade and HIF-1α activation

Spontaneous overexpression of endogenous IRIS, an alternatively spliced product of the tumor suppressor gene BRCA1, allows it to function as an oncoprotein that stimulates a potentially lethal outcome, i.e. metastasis of human cancer cells to tissues served, in part, by the arterial circulation. It does so by suppressing phosphatase and tensin homolog (PTEN) mRNA synthesis, thereby stabilizing and activating HIF-1α in normoxic cells. Thus, this study provides a strong rationale for exploring the therapeutic value of interfering with spontaneously overexpressed IRIS function in multiple types of tumors that can naturally overexpress it.

BRCA1 is an established breast and ovarian tumor suppressor gene that encodes multiple protein products whose individual contributions to human cancer suppression are poorly understood. BRCA1-IRIS (also known as “IRIS”), an alternatively spliced BRCA1 product and a chromatin-bound replication and transcription regulator, is overexpressed in various primary human cancers, including breast cancer, lung cancer, acute myeloid leukemia, and certain other carcinomas. Its naturally occurring overexpression can promote the metastasis of patient-derived xenograft (PDX) cells and other human cancer cells in mouse models. The IRIS-driven metastatic mechanism results from IRIS-dependent suppression of phosphatase and tensin homolog (PTEN) transcription, which in turn perturbs the PI3K/AKT/GSK-3β pathway leading to prolyl hydroxylase-independent HIF-1α stabilization and activation in a normoxic environment. Thus, despite the tumor-suppressing genetic origin of IRIS, its properties more closely resemble those of an oncoprotein that, when spontaneously overexpressed, can, paradoxically, drive human tumor progression.

SPAG6 silencing induces apoptosis in the myelodysplastic syndrome cell line SKM‑1 via the PTEN/PI3K/AKT signaling pathway in vitro and in vivo

Apoptosis is a multi-step mechanism of cell self‑destruction for maintaining cellular homeostatic balance. Accumulating evidence indicates that abnormal apoptosis promotes the evolution and progression of myelodysplastic syndromes (MDS). As a novel cancer-testis antigen, sperm‑associated antigen 6 (SPAG6) has been reported to regulate apoptosis through the tumor necrosis factor-related apoptosis-inducing ligand signaling pathway in the MDS cell line SKM‑1. However, the mechanism of the intrinsic cell death pathway for apoptosis induction by SPAG6 silencing is unclear. In the present study, the in vitro effects of SPAG6 silencing were investigated in SKM‑1 cells through extensive biochemical and molecular approaches. Western blotting and reverse transcription-quantitative polymerase chain reaction were used to detect the expression of SPAG6 and activation of PTEN/PI3K/AKT signal pathway. Additionally, SKM‑1 cells transduced with SPAG6 short hairpin RNA (shRNA) lentivirus were treated with the phosphatidylionositol 3-kinase (PI3K) inhibitor LY294002 or pan caspase inhibitor z‑VAD‑fmk and the apoptosis rates were measured by flow cytometry, and the expressions of associated proteins were examined by western blot analysis. A mouse xenograft model was also used to further evaluate the effects of SPAG6 knockdown on inducing tumor apoptosis in vivo. Lentivirus-mediated knockdown of SPAG6 in SKM‑1 cells increased phosphatase and tensin homolog (PTEN) expression and reduced protein kinase B (AKT) phosphorylation, which in turn resulted in cell apoptosis as evidenced by induced myeloid leukaemia cell differentiation protein Mcl‑1 downregulation, cytochrome c release and increased caspase‑9 expression. Consistently, the PI3K inhibitor LY294002 synergistically enhanced apoptosis of SKM‑1 cells when co-administered with SPAG6 shRNA lentivirus. Furthermore, treatment with the pan caspase inhibitor z‑VAD‑fmk failed to prevent PTEN activation upon SPAG6 knockdown, suggesting that SPAG6-regulated PTEN expression was caspase activation-independent. In addition, SPAG6 knockdown was associated with DNMT1 downregulation, implying that SPAG6 may indirectly control PTEN expression via DNA methylation. Furthermore, tumor tissues from nonobese diabetic/severe combined immunodeficient mice inoculated with SPAG6-shRNA lentivirus pre-infected SKM‑1 cells exhibited significantly elevated apoptosis in the extrinsic and intrinsic pathways. These results demonstrate that SPAG6 silencing induces PTEN expression to regulate apoptosis though the PI3K/AKT pathway, indicating that SPAG6 may be a potential therapeutic target for MDS.

The prognostic value and potential drug target of phosphatase and tensin homolog in breast cancer patients: A meta-analysis

BACKGROUND

The prognostic significance of phosphatase and tensin homolog (PTEN) in patients with breast cancer (BC) remains controversial. The aims of our meta-analysis are to evaluate its association with clinicopathological characteristics and prognostic value in patients with breast cancer.

METHODS

PubMed, EMBASE, Web of Science, and China National Knowledge Infrastructure (CNKI) were systematically searched up to December 2016. The meta-analysis was performed using hazard ratio (HR), odds ratio (OR), and 95% confidence intervals (CI) as effect measures. A fixed or random effect model was used depending on the heterogeneity analysis. Statistical analysis was performed using Review manager software version 5.3.

RESULTS

Seventeen studies including 4343 patients with breast cancer were analyzed. The meta-analysis indicated that breast cancers with PTEN loss were significantly associated with the tumor size ≥2 cm group (ORFEM = 1.68, 95%CIFEM [1.34, 2.10]), negative expression of estrogen receptor (ORREM = 1.95, 95%CIREM [1.09, 3.49]), negative expression of progesterone receptor (ORFEM = 1.72, 95%CIFEM [1.43, 2.08]), the advanced stage (ORREM = 1.94, 95%CIREM [1.35, 2.80]), positive axillary lymph node metastasis (ORREM = 1.80, 95%CIREM [1.30, 2.50]), and the local recurrence (ORFEM = 1.70, 95%CIFEM [1.26, 2.28]). None of other clinicopathological parameters such as the HER2 status and distant metastasis were associated with PTEN loss. The decreased PTEN expression was significantly correlated with the overall survival (OS) of patients (HRREM = 1.83, 95%CIREM [1.32, 2.53]) and the disease-free survival (DFS) of patients (HRREM = 2.43, 95%CIREM [1.31, 4.53]).

CONCLUSION

Our meta-analysis demonstrates that PTEN loss is of particular importance for predicting breast cancer aggressiveness and poor prognosis. PTEN is a potential drug target for the development of individualized treatment in BC patients.

Significantly mutated genes and regulatory pathways in SCLC-a meta-analysis

Small cell lung cancer (SCLC) accounts for approximately 15% of all lung cancers and demands effective targeted therapeutic strategies. In this meta-analysis study, we aim to identify significantly mutated genes and regulatory pathways to help us better understand the progression of SCLC and to identify potential biomarkers. Besides ranking genes based on their mutation frequencies, we sought to identify statistically significant mutations in SCLC with the MutSigCV software. Our analysis identified several genes with relatively low mutation frequency, including PTEN, as highly significant (p < 0.001), suggesting these genes may play an important role in the progression of SCLC. Our results also indicated mutations in genes involved in the axon guidance pathways likely play an important role in SCLC progression. In addition, we observed that the mutation rate was significantly higher in samples with RB1 gene mutated when compared to samples with wild type RB1, suggesting that RB1 status has significant impact on the mutation profile and disease progression in SCLC.

The association of PTEN hypermethylation and breast cancer: a meta-analysis

OBJECTIVE

Phosphatase and tensin homolog (PTEN) deleted on chromosome 10, as a tumor suppressor gene, is crucial for the development of both familial and sporadic breast cancer (BC). The aim of this study was to perform a meta-analysis to evaluate the clinicopathological significance of PTEN promoter hypermethylation in BC.

METHODS

A comprehensive literature search was made in PubMed, Embase, Google Scholar, Chinese database (China National Knowledge Infrastructure [CNKI]), and Web of Science. The analysis of pooled data was performed with Review Manager 5.2. The fixed-effects or random-effects models were used to evaluate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The meta-analysis included eight studies and a total of 923 patients. The frequency of PTEN promoter hypermethylation was significantly increased in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) compared to normal breast tissues (OR =22.53, P=0.0002 and OR =22.86, P<0.00001, respectively). However, the frequency of PTEN promoter hypermethylation was similar between IDC and DCIS. Additionally, PTEN methylation was not significantly correlated to estrogen receptor (ER) or human epidermal growth factor type 2 (HER-2) status in patients with BC.

CONCLUSION

PTEN promoter hypermethylation is significantly associated with the risk of DCIS and IDC, suggesting PTEN promoter hypermethylation is a valuable biomarker for diagnosis of BC.

The prognostic value of phosphatase and tensin homolog negativity in breast cancer: A systematic review and meta-analysis of 32 studies with 4393 patients

The prognostic value of phosphatase and tensin homolog (PTEN) negativity in breast cancer has been evaluated by many studies but remains controversial. We conducted a meta-analysis to assess the association of PTEN negativity with overall survival and disease-free survival. Thirty-two studies with 4393 patients were identified. PTEN negativity was significantly associated with unfavorable overall survival in breast cancer (hazard ratio=1.89, 95% confidence interval 1.58-2.26), with low heterogeneity among the studies (I(2)=25%, P=0.160) and no evidence for publication bias. Meta-analysis of multivariate hazard ratios and sensitivity analyses did not materially change the results. The data on disease-free survival was heterogeneous (I(2)=61.9%, P<0.001), with a summary hazard ratio of 1.57 (95% confidence interval 1.31-1.89). The exact source of heterogeneity remains unclear. We thus concluded that PTEN negativity was significantly associated with unfavorable prognosis in terms of overall survival in breast cancer.

Timing of the loss of Pten protein determines disease severity in a mouse model of myeloid malignancy

Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric mixed myelodysplastic/myeloproliferative neoplasm (MDS/MPN). JMML leukemogenesis is linked to a hyperactivated RAS pathway, with driver mutations in the KRAS, NRAS, NF1, PTPN11, or CBL genes. Previous murine models demonstrated how those genes contributed to the selective hypersensitivity of JMML cells to granulocyte macrophage-colony-stimulating factor (GM-CSF), a unifying characteristic in the disease. However, it is unclear what causes the early death in children with JMML, because transformation to acute leukemia is rare. Here, we demonstrate that loss of Pten (phosphatase and tensin homolog) protein at postnatal day 8 in mice harboring Nf1 haploinsufficiency results in an aggressive MPN with death at a murine prepubertal age of 20 to 35 days (equivalent to an early juvenile age in JMML patients). The death in the mice was due to organ infiltration with monocytes/macrophages. There were elevated activities of protein kinase B (Akt) and mitogen-activated protein kinase (MAPK) in cells at physiological concentrations of GM-CSF. These were more pronounced in mice with Nf1 haploinsufficiency than in littermates with wild-type Nf1,but this model is insufficient to cause cells to be GM-CSF hypersensitive. This new model represents a murine MPN model with features of a pediatric unclassifiable mixed MDS/MPN and mimics many clinical manifestations of JMML in terms of age of onset, aggressiveness, and organ infiltration with monocytes/macrophages. Our data suggest that the timing of the loss of PTEN protein plays a critical role in determining the disease severity in myeloid malignancies. This model may be useful for studying the pathogenesis of pediatric diseases with alterations in the Ras pathway.

SMAD4 expression in breast ductal carcinoma correlates with prognosis

The present study examined SMAD4 expression in fine-needle aspiration cell blocks from patients with breast ductal carcinoma, in order to assess its viability as a prognostic marker. Using immunohistochemistry, the SMAD4 protein status of 86 breast ductal carcinoma fine-needle biopsies, from patients who underwent tumor resection at Beihua University Affiliated Hospital (Jilin, China) between 2002 and 2008, was characterized. The association between SMAD4 expression and clinicopathological parameters, as well as prognosis was assessed using the Mantel-Haenszel method and Cox proportional hazards regression. SMAD4 staining was observed in the cytoplasm and nucleus, and its expression was found to be decreased in ductal breast carcinoma as compared with adjacent normal breast epithelia. Patients with reduced SMAD4 expression levels tended to exhibit more poorly differentiated tumors, a higher risk of recurrence and shorter overall survival. These results demonstrated that the evaluation of SMAD4 protein status in fine-needle biopsy specimens of breast ductal carcinoma may provide additional prognostic information.

PI3KCA mutation status is of limited prognostic relevance in ER-positive breast cancer patients treated with hormone therapy

PI3K/AKT/mTOR pathway alterations are frequent in patients with infiltrating breast cancer (IBC). Their clinical and pathological relevance has been insufficiently documented. We evaluated PI3KCA for mutations and the expression of PTEN, AKT, mTOR and p70S6K by immunohistochemistry in 246 IBC patients treated with hormone therapy (median follow-up, 97 months). A PI3KCA mutation was observed in 50 out of 229 informative cases (21.8 %), PTEN loss in 107 out of 210 (51 %), moderate/high level of expression of AKT in 133 out of 188 (71 %), moderate/high level of expression of mTOR in 173 out of 218 (79 %) and moderate/high level of expression of p70S6K in 111 out of 192 cases (58 %). PI3KCA mutation was associated with the absence of Her2/neu amplification/overexpression and a low level of MIB1/Ki-67 labelling. The expression of p70S6K was associated with a high level of mTOR immunoreactivity, and high PTEN expression was associated with high AKT expression level. Univariate analysis showed that PI3KCA mutation status was not associated with clinical outcome in the series as a whole or in the node-negative subgroup. However, in the node-positive subgroup, exon 9 PI3KCA mutation was associated with unfavourable overall survival (OS), although its impact on the final model in multivariate analysis seemed to be limited. Of the other markers, only high p70S6K expression was associated with a significantly prolonged OS. PI3KCA mutation status is of limited prognostic relevance in oestrogen receptor-positive breast cancer patients treated with hormone therapy.

Cytokeratin 5/6, c-Met expressions, and PTEN loss prognostic indicators in triple-negative breast cancer

In subgroups of breast cancer, the shortest disease-free and overall survival was observed in basaloid and human epidermal growth factor receptor-2 groups. CK5/6 expression is a marker used in diagnosing breast cancers in basaloid group and is associated with a poor prognosis. Similarly, loss of tumor suppressor gene PTEN and a high expression of c-Met has been associated with poor prognosis in breast cancer and many other cancers. In this study, we aimed to determine the effect of CK5/6 and c-Met expressions, and PTEN loss on the disease prognosis in triple-negative breast cancer patients. Ninety-seven patients pathologically diagnosed with triple-negative breast cancer were enrolled. The clinical and pathological characteristics of the patients were recorded. c-Met, PTEN, and CK5/6 expressions were evaluated with immunohistochemical methods from paraffin blocks. The median age of patients was 47 years. CK5/6 positivity was 50.5 %, PTEN loss was 44.3 %, and high c-Met expression was detected in 53.6 %. In multivariate analysis, predictors of the recurrence were loss of PTEN (HR = 2.99; P = 0.004), high c-Met expression (HR = 2.05; P = 0.06), CK5/6 expression (HR = 2.99; P = 0.02), increase in the number of metastatic lymph nodes (HR = 1.11; P = 0.001), and an increase in tumor size (HR = 1.226; P = 0.01). Also, PTEN loss (HR = 2.43; P = 0.05), CK5/6 expression (HR = 3.74; P = 0.01), and N2-3 tumors compared to negatives (HR = 3.63; P = 0.01) were associated with death. PTEN loss correlated with those of lymphovascular invasion. There was a correlation between CK5/6 expression and the number of metastatic lymph nodes. Also, a correlation was found among cancers with highly expressed levels of c-Met, T1-2 tumors, and high-grade tumors. The classical markers, lymph node involvement and tumor size, were found to be of prognostic value; however, high c-Met and CK5/6 expressions, and PTEN loss were found to increase risk of recurrence and death in patients with triple-negative breast cancer.

In MMTV-Her-2/neu transgenic mammary tumors the absence of caveolin-1-/- alters PTEN and NHERF1 but not β-catenin expression

In a recent study, we have shown that in mammary tumors from mice lacking the Cav-1 gene, there are alterations in specific heat shock proteins as well as in tumor development. With this in mind, we have now investigated other proteins in the same mammary mouse tumor model (Her-2/neu expressing mammary tumors from Cav-1 wild type and Cav-1 null mice), to further comprehend the complex tumor-stroma mechanisms involved in regulating stress responses during tumor development. In this tumor model the cancer cells always lacked of Cav-1, so the KO influenced the Cav-1 in the stroma. By immunohistochemistry, we have found a striking co-expression of β-catenin and Her-2/neu in the tumor cells. The absence of Cav-1 in the tumor stroma had no effect on expression or localization of β-catenin and Her-2/neu. Both proteins appeared co-localized at the cell surface during tumor development and progression. Since Her-2/neu activation induces MTA1, we next evaluated MTA1 in the mouse tumors. Although this protein was found in numerous nuclei, the absence of Cav-1 did not alter its expression level. In contrast, significantly more PTEN protein was noted in the tumors lacking Cav-1 in the stroma, with the protein localized mainly in the nuclei. P-Akt levels were relatively low in tumors from both Cav-1 WT and Cav-1 KO mice. There was also an increase in nuclear NHERF1 expression levels in the tumors arising from Cav-1 KO mice. The data obtained in the MMTV-neu model are consistent with a role for Cav-1 in adjacent breast cancer stromal cells in modulating the expression and localization of important proteins implicated in tumor cell behavior.

Carboxyl-terminal modulator protein positively regulates Akt phosphorylation and acts as an oncogenic driver in breast cancer

Akt activation has been implicated broadly in tumorigenesis, but the basis for its dysregulation in cancer cells is incompletely understood. In this study, we sought to clarify a regulatory role for the Akt-binding carboxy-terminal modulator protein (CTMP), which has been controversial. In evaluating CTMP expression in paired normal-tumor specimens of 198 patients with breast cancer, we found that CTMP was upregulated in breast tumors, where it was associated with poor patient survival. Notably, CTMP expression also correlated positively with Akt phosphorylation in breast cancer clinical specimens and cell lines. Furthermore, ectopic expression of CTMP promoted cell proliferation and enhanced the tumorigenic properties of estrogen-dependent breast cancer cells. This effect was correlated with increased sensitivity to insulin-induced Akt phosphorylation, which is mediated primarily by the phosphoinositide 3-kinase-Akt pathway. In contrast, short hairpin RNA-mediated silencing of endogenous CTMP decreased the proliferation of estrogen-dependent or estrogen-independent breast cancer cells. Mechanistic investigations defined the N-terminal domain of CTMP at amino acids 1 to 64 as responsible for Akt binding. Taken together, our results firmly corroborate the concept that CTMP promotes Akt phosphorylation and functions as an oncogenic molecule in breast cancer.

PI3K in cancer-stroma interactions: bad in seed and ugly in soil

Over the past decade the phosphoinositide-3 kinase (PI3K) signaling pathway emerged as an important player for tumor initiation and growth and, currently, PI3K inhibition constitutes a promising therapeutic approach for solid and hematological tumors. Beside its role in tumor cell evolution, PI3K signaling also provides integral functions for noncancerous cells that reside in healthy tissues surrounding the tumor, also referred as tumor microenvironment (TME). This review will address how PI3K signaling participates to the tumorigenic process and discuss the interaction between tumor cells and the surrounding TME, with particular focus on the role of PI3Ks in tumor-associated immune responses, tumor angiogenesis and metastasis formation.

Inhibition of miR-21 induces biological and behavioral alterations in diffuse large B-cell lymphoma

MicroRNA-21 (miR-21) has been ascribed a key role in many cellular processes, e.g. tumorigenesis via inhibition of target gene expression. However, its role in diffuse large B-cell lymphoma (DLBCL) is still unclear, and there are no in-depth studies on the relationship between miR-21 and the cellular phenotype of DLBCL. In this study, we investigated the expression and role of miR-21 in the regulation of cell biological processes in DLBCL. Firstly, miR-21 expression was evaluated in three DLBCL cell lines by real-time quantitative reverse-transcription (qRT) polymerase chain reaction (PCR). Then, to determine the possible role of miR-21 in the biological and behavioral characteristics of DLBCL, we performed miR-21 knockdown by transfection with anti-miR-21. In addition, PDCD4 and PTEN were assessed by luciferase reporter assay, qRT-PCR, and Western blot. Our study revealed that miR-21 was significantly upregulated in activated B-cell-like DLBCL cells compared to germinal center-like DLBCL cells. We demonstrated that inhibition of miR-21 induced suppression of proliferation and invasion, as well as increased apoptosis in DLBCL. Moreover, knockdown of miR-21 increased PDCD4 and PTEN expression at the protein level but not at the mRNA level. In conclusion, miR-21 can regulate proliferation, invasion, and apoptosis, and thus it has a potential therapeutic application in DLBCL.

Germline and somatic KLLN alterations in breast cancer dysregulate G2 arrest

PTEN is a well-described predisposition gene for Cowden syndrome (CS), a familial cancer syndrome characterized by a high risk of breast and other cancers. KLLN, which shares a bidirectional promoter with PTEN, causes cell cycle arrest and apoptosis. We previously identified germline hypermethylation of the KLLN promoter in 37% of PTEN mutation-negative CS/CS-like (CSL) patients. Patients with germline KLLN hypermethylation have an increased prevalence of breast and renal cancers when compared with PTEN mutation carriers. We have consequently sought to identify and characterize germline KLLN variants/mutations in CS/CSL and in apparently sporadic breast cancer patients. KLLN variants in CS/CSL patients are rare (1 of 136, 0.007%). Interestingly, among 438 breast cancer patients, 13 (3%) have germline KLLN variants when compared with none in 128 controls (P = 0.049). Patients with KLLN variants have a family history of breast cancer when compared with those without (P = 0.02). We demonstrate that germline KLLN variants dysregulate the cell cycle at G2. Of 24 breast carcinomas analyzed, 3 (13%) have somatic KLLN hemizygous deletions, with somatic loss of the wild-type allele in a patient with germline KLLN p.Leu119Leu. Of 452 breast carcinomas in The Cancer Genome Atlas project, 93 (21%) have KLLN hemizygous or homozygous deletions. This is the first study to associate germline KLLN variants with sporadic breast cancer and to recognize somatic KLLN deletions in breast carcinomas. Our observations suggest that KLLN may be a low penetrance susceptibility factor for apparently sporadic breast cancer.

Comprehensive analysis of PTEN status in breast carcinomas

PTEN plays a well-established role in the negative regulation of the PI3K pathway, which is frequently activated in several cancer types, including breast cancer. A nuclear function in the maintenance of chromosomal stability has been proposed for PTEN but is yet to be clearly defined. In order to improve understanding of the role of PTEN in mammary tumorigenesis in terms of a possible gene dosage effect, its PI3K pathway function and its association with p53, we undertook comprehensive analysis of PTEN status in 135 sporadic invasive ductal carcinomas. Four PTEN status groups were defined; complete loss (19/135, 14%), reduced copy number (19/135, 14%), normal (86/135, 64%) and complex (11/135, 8%). Whereas the PTEN complete loss status was significantly associated with estrogen receptor (ER) negativity (p=0.006) and in particular the basal-like phenotype (p<0.0001), a reduced PTEN copy number was not associated with hormone receptor status or a particular breast cancer subtype. Overall, PI3K pathway alteration was suggested to be involved in 59% (79/134) of tumors as assessed by human epidermal growth factor receptor 2 overexpression, PIK3CA mutation or a complete loss of PTEN. A complex PTEN status was identified in a tumor subgroup which displayed a specific, complex DNA profile at the PTEN locus with a strikingly similar highly rearranged pan-genomic profile. All of these tumors had relapsed and were associated with a poorer prognosis in the context of node negative disease (p=1.4 × 10(-13) ) thus may represent a tumor subgroup with a common molecular alteration which could be targeted to improve clinical outcome.

Molecular mapping the presence of druggable targets in preinvasive and precursor breast lesions: a comprehensive review of biomarkers related to therapeutic interventions

The analysis of clinical breast samples using biomarkers is integral to current breast cancer management. Currently, a limited number of targeted therapies are standard of care in breast cancer treatment. However, these targeted therapies are only suitable for a subset of patients and resistance may occur. Strategies to prevent the occurrence of invasive lesions are required to reduce the morbidity and mortality associated with the development of cancer. In theory, application of targeted therapies to pre-invasive lesions will prevent their progression to invasive lesions with full malignant potential. The diagnostic challenge for pathologists is to make interpretative decisions on early detected pre-invasive lesions. Overall, only a small proportion of these pre-invasive lesions will progress to invasive carcinoma and morphological assessment is an imprecise and subjective means to differentiate histologically identical lesions with varying malignant potential. Therefore differential biomarker analysis in pre-invasive lesions may prevent overtreatment with surgery and provide a predictive indicator of response to therapy. There follows a review of established and emerging potential druggable targets in pre-invasive lesions and correlation with lesion morphology.

Everolimus and its role in hormone-resistant and trastuzumab-resistant metastatic breast cancer

Advances in targeted therapies have improved progression-free and overall survival in women with metastatic breast cancer; however, regardless of efficacy, resistance almost always occurs eventually. Upregulation of the PI3K/AKT/mTOR pathway, which promotes cell growth and proliferation, is a means of escaping responsiveness to hormone therapy in hormone receptor-positive disease, or trastuzumab in HER2-positive disease. Everolimus, an inhibitor of mTOR, has shown promise in early clinical trials in metastatic breast cancer and is currently being studied in larger Phase II and III clinical trials, combined with hormone therapy or trastuzumab with or without cytotoxic chemotherapy. In this article, we discuss the mechanistic and preclinical data for everolimus, efficacy and safety results of clinical trials, and the landscape looking forward.

Mutations and deregulation of Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades which alter therapy response

The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Certain components of these pathways, RAS, NF1, BRAF, MEK1, DUSP5, PP2A, PIK3CA, PIK3R1, PIK3R4, PIK3R5, IRS4, AKT, NFKB1, MTOR, PTEN, TSC1, and TSC2 may also be activated/inactivated by mutations or epigenetic silencing. Upstream mutations in one signaling pathway or even in downstream components of the same pathway can alter the sensitivity of the cells to certain small molecule inhibitors. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of components of these cascades can contribute to: resistance to other pathway inhibitors, chemotherapeutic drug resistance, premature aging as well as other diseases. This review will first describe these pathways and discuss how genetic mutations and epigenetic alterations can result in resistance to various inhibitors.

PTEN as a prognostic and predictive marker in postoperative radiotherapy for squamous cell cancer of the head and neck

Background

Tumor suppressor PTEN is known to control a variety of processes related to cell survival, proliferation, and growth. PTEN expression is considered as a prognostic factor in some human neoplasms like breast, prostate, and thyroid cancer.

Methodology/Principal Findings

In this study we analyzed the influence of PTEN expression on the outcome of a randomized clinical trial of conventional versus 7-days-a-week postoperative radiotherapy for squamous cell cancer of the head and neck. The patients with cancer of the oral cavity, oropharynx, and larynx were randomized to receive 63 Gy in fractions of 1.8 Gy given 5 days a week (CF) or 7 days a week (p-CAIR). Out of 279 patients enrolled in the study, 147 paraffin blocks were available for an immunohistochemical assessment of PTEN. To evaluate the prognostic value of PTEN expression and the effect of fractionation relative to PTEN, the data on the outcome of a randomized clinical trial were analyzed. Tumors with a high intensity of PTEN staining had significant gain in the loco-regional control (LRC) from p-CAIR (5-year LRC 92.7% vs. 70.8%, for p-CAIR vs. CF, p = 0.016, RR = 0.26). By contrast, tumors with low intensity of PTEN did not gain from p-CAIR (5-year LRC 56.2% vs. 47.2%, p = 0.49, RR = 0.94). The intensity of PTEN highly affected the LRC in a whole group of 147 patients (5-year LRC 80.9% vs. 52.3% for high vs. low PTEN, p = 0.0007, RR = 0.32). In multivariate Cox analysis, including neck node involvement, EGFR, nm23, Ki-67, p53, cyclin D1, tumor site and margins, PTEN remained an independent predictor of LRC (RR = 2.8 p = 0.004).

Conclusions/Significance

These results suggest that PTEN may serve as a potent prognostic and predictive marker in postoperative radiotherapy for high-risk squamous cell cancer of the head and neck.

Involvement of Akt-1 and mTOR in sensitivity of breast cancer to targeted therapy

Elucidating the response of breast cancer cells to chemotherapeutic and hormonal based drugs is clearly important as these are frequently used therapeutic approaches. A signaling pathway often involved in chemo- and hormonal-resistance is the Ras/PI3K/PTEN/Akt/mTOR cascades. In the studies presented in this report, we have examined the effects of constitutive activation of Akt on the sensitivity of MCF-7 breast cancer cells to chemotherapeutic- and hormonal-based drugs as well as mTOR inhibitors. MCF-7 cells which expressed a constitutively-activated Akt-1 gene [∆Akt-1(CA)] were more resistant to doxorubicin, etoposide and 4-OH-tamoxifen (4HT) than cells lacking ∆Akt-1(CA). Cells which expressed ∆Akt-1(CA) were hypersensitive to the mTOR inhibitor rapamycin. Furthermore, rapamycin lowered the IC50s for doxorubicin, etoposide and 4HT in the cells which expressed ∆Akt-1(CA), demonstrating a potential improved method for treating certain breast cancers which have deregulated PI3K/PTEN/Akt/mTOR signaling. Understanding how breast cancers respond to chemo- and hormonal-based therapies and the mechanisms by which they can become drug resistant may enhance our ability to treat breast cancer. These results also document the potential importance of knowledge of the mutations present in certain cancers which may permit more effective therapies.

Cooperative effects of Akt-1 and Raf-1 on the induction of cellular senescence in doxorubicin or tamoxifen treated breast cancer cells

Escape from cellular senescence induction is a potent mechanism for chemoresistance. Cellular senescence can be induced in breast cancer cell lines by the removal of estrogen signaling with tamoxifen or by the accumulation of DNA damage induced by the chemotherapeutic drug doxorubicin. Long term culturing of the hormone-sensitive breast cancer cell line MCF-7 in doxorubicin (MCF-7/DoxR) reduced the ability of doxorubicin, but not tamoxifen, to induce senescence. Two pathways that are often upregulated in chemo- and hormonal-resistance are the PI3K/PTEN/Akt/mTOR and Ras/Raf/MEK/ERK pathways. To determine if active Akt-1 and Raf-1 can influence drug-induced senescence, we stably introduced activated ΔAkt-1(CA) and ΔRaf-1(CA) into drug-sensitive and doxorubicin-resistant cells. Expression of a constitutively-active Raf-1 construct resulted in higher baseline senescence, indicating these cells possessed the ability to undergo oncogene-induced-senescence. Constitutive activation of the Akt pathway significantly decreased drug-induced senescence in response to doxorubicin but not tamoxifen in MCF-7 cells. However, constitutive Akt-1 activation in drug-resistant cells containing high levels of active ERK completely escaped cellular senescence induced by doxorubicin and tamoxifen. These results indicate that up regulation of the Ras/PI3K/PTEN/Akt/mTOR pathway in the presence of elevated Ras/Raf/MEK/ERK signaling together can contribute to drug-resistance by diminishing cell senescence in response to chemotherapy. Understanding how breast cancers containing certain oncogenic mutations escape cell senescence in response to chemotherapy and hormonal based therapies may provide insights into the design of more effective drug combinations for the treatment of breast cancer.

Variants on the promoter region of PTEN affect breast cancer progression and patient survival

Introduction

The PTEN gene, a regulator of the phosphatidylinositol-3-kinase (PI3K)/Akt oncogenic pathway, is mutated in various cancers and its expression has been associated with tumor progression in a dose-dependent fashion. We investigated the effect of germline variation in the promoter region of the PTEN gene on clinical characteristics and survival in breast cancer.

Methods

We screened the promoter region of the PTEN gene for germline variation in 330 familial breast cancer cases and further determined the genotypes of three detected PTEN promoter polymorphisms -903GA, -975GC, and -1026CA in a total of 2,412 breast cancer patients to evaluate the effects of the variants on tumor characteristics and disease outcome. We compared the gene expression profiles in breast cancers of 10 variant carriers and 10 matched non-carriers and performed further survival analyses based on the differentially expressed genes.

Results

All three promoter variants associated with worse prognosis. The Cox's regression hazard ratio for 10-year breast cancer specific survival in multivariate analysis was 2.01 (95% CI 1.17 to 3.46) P = 0.0119, and for 5-year breast cancer death or distant metastasis free survival 1.79 (95% CI 1.03 to 3.11) P = 0.0381 for the variant carriers, indicating PTEN promoter variants as an independent prognostic factor. The breast tumors from the promoter variant carriers exhibited a similar gene expression signature of 160 differentially expressed genes compared to matched non-carrier tumors. The signature further stratified patients into two groups with different recurrence free survival in independent breast cancer gene expression data sets.

Conclusions

Inherited variation in the PTEN promoter region affects the tumor progression and gene expression profile in breast cancer. Further studies are warranted to establish PTEN promoter variants as clinical markers for prognosis in breast cancer.

Expression of PTEN in basaloid squamous cell carcinoma and its clinicopathological significance

There are a few ideal predictors that are used to evaluate the prognosis of basaloid squamous cell carcinoma (BSCC). This study was designed to investigate the expression of PTEN (phosphates and tensin homolog deleted on chromosome ten) and its association with clinicopathological and available follow-up data. PTEN protein was examined by using immunohistochemical SABC staining method in eight cases of BSCC. Loss of PTEN expression was noted in five (62.5%) of the eight studied BSCC cases. Statistically, there was a significant relationship between PTEN expression and studied BSCC groups depending upon the basaloid component level, lymph node involvement, and the clinical stage of the disease. Of the five patients whose tumors were PTEN negative, three (80%) had recurrence or death at follow-up, whereas none of the three patients whose tumors were PTEN positive had recurrence or death. It was concluded that the PTEN positive expression may be useful for predicting the prognosis of BSCC.

MGMT and PTEN as potential prognostic markers in breast cancer

AIM

To evaluate the prognostic importance of MGMT and PTEN concerning their correlation with other prognostic factors evaluated by immunohistochemistry (IHC) and the molecular phenotype of breast cancers.

METHODS

IHC for estrogen and progesterone receptors, HER2, Ki67, p53, p63, e-cadherin, EGFR, CK5, CK14, MGMT and PTEN was performed on 200 breast tumors. Basal-like and luminal breast carcinomas were defined by the IHC evaluation of these markers. Fluorescent in situ hybridization (FISH) was performed for PTEN and HER2 analysis using the Vysis PTEN and HER2 DNA probe kits (Abbott™). RT-PCR was performed to evaluate gene expressions of MGMT and PTEN in frozen tissue of 59/200 cases.

RESULTS

147/200 cases were triple-negative (73.5%), 47/147 were basal-like carcinomas (31.9%). 53 cases (26.5%) were luminal-like type A or B. 56 (93.3%) and 46 samples (76.6%) expressed lower levels of MGMT and PTEN mRNA, respectively, compared with normal breast (p<0.001). There was a positive correlation between the IHC results and the RT-PCR values for MGMT and PTEN. Tumors with homozygotic deletion of PTEN expressed little or no mRNA or protein. Positive p53, high Ki67, and basal-like tumors expressed significant lower MGMT and PTEN.

CONCLUSIONS

We hypothesize that MGMT and PTEN expressions have prognostic significance in breast cancer. Also, based on their predictive value of response to therapy, evaluating MGMT and PTEN and learning to interpret their patterns of immunoexpression will undoubtedly lead to a greater understanding of breast cancer and its treatment.

Involvement of Akt and mTOR in chemotherapeutic- and hormonal-based drug resistance and response to radiation in breast cancer cells

Elucidating the response of breast cancer cells to chemotherapeutic and hormonal based drugs and radiation is clearly important as these are common treatment approaches. Signaling cascades often involved in chemo-, hormonal- and radiation resistance are the Ras/PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK and p53 pathways. In the following studies we have examined the effects of activation of the Ras/PI3K/PTEN/Akt/mTOR cascade in the response of MCF-7 breast cancer cells to chemotherapeutic- and hormonal-based drugs and radiation. Activation of Akt by introduction of conditionally-activated Akt-1 gene could result in resistance to chemotherapeutic and hormonal based drugs as well as radiation. We have determined that chemotherapeutic drugs such as doxorubicin or the hormone based drug tamoxifen, both used to treat breast cancer, resulted in the activation of the Raf/MEK/ERK pathway which is often associated with a pro-proliferative, anti-apoptotic response. In drug sensitive MCF-7 cells which have wild-type p53; ERK, p53 and downstream p21 (Cip-1 ) were induced upon exposure to doxorubicin. In contrast, in the drug resistant cells which expressed activated Akt-1, much lower levels of p53 and p21 (Cip1) were induced upon exposure to doxorubicin. These results indicate the involvement of the Ras/PI3K/PTEN/Akt/mTOR, Ras/Raf/MEK/ERK and p53 pathways in the response to chemotherapeutic and hormonal based drugs. Understanding how breast cancers respond to chemo- and hormonal-based therapies and radiation may enhance the ability to treat breast cancer more effectively.

Roles of the Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways in controlling growth and sensitivity to therapy-implications for cancer and aging

Dysregulated signaling through the Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR pathways is often the result of genetic alterations in critical components in these pathways or upstream activators. Unrestricted cellular proliferation and decreased sensitivity to apoptotic-inducing agents are typically associated with activation of these pro-survival pathways. This review discusses the functions these pathways have in normal and neoplastic tissue growth and how they contribute to resistance to apoptotic stimuli. Crosstalk and commonly identified mutations that occur within these pathways that contribute to abnormal activation and cancer growth will also be addressed. Finally the recently described roles of these pathways in cancer stem cells, cellular senescence and aging will be evaluated. Controlling the expression of these pathways could ameliorate human health.

Does the PI3K pathway play a role in basal breast cancer?

Many cell kinases exert their proliferative and pro-survival effects through activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Basal-like breast cancer is a subtype that can be identified by molecular analysis and often includes tumors lacking expression of estrogen receptor/progesterone receptor or human epidermal growth factor receptor, also known as triple-negative breast cancers. Triple-negative cancers comprise < 20% of all breast cancers and have no obvious mechanism driving proliferation, yet these tumors demonstrate higher levels of Akt activation compared with non-triple-negative breast cancers. This suggests a possible role for targeting the PI3K pathway for the treatment of this subset of aggressive cancers. Most clinical trials which have attempted targeting the PI3K/Akt pathway in triple-negative breast cancer have involved the use of EGFR inhibitors with limited success. Novel agents targeting PI3K are under development in early-phase clinical trials and may demonstrate benefit in combination with chemotherapy or other targeted agents such as mitogen-activated protein kinase inhibitors for the treatment of triple-negative or basal-like breast cancer.

Biomarkers and patient selection for PI3K/Akt/mTOR targeted therapies: current status and future directions

The phosphatidylinositol 3-kinase (PI3K)/Akt/ mammalian target of rapamycin (mTOR) pathway regulates a broad spectrum of physiologic and pathologic processes. In breast cancer mutation, amplification, deletion, methylation, and posttranslational modifications lead to significant dysregulation of this pathway leading to more aggressive and potentially drug-resistant disease. Multiple novel agents, targeting different nodes within the pathway are currently under development by both commercial and academic partners. The key to the successful validation of these markers is selection of the appropriate patient groups using biomarkers. This article reviews current progress in this area, highlighting the key molecular alterations described in genes within the PI3K/Akt/mTOR pathway that may have an effect on response to current and future therapeutic interventions. Herein, gaps in current knowledge are highlighted and suggestions for future research directions given that may facilitate biomarker development in partnership with current drug development.

PI3K pathway activation results in low efficacy of both trastuzumab and lapatinib

Background

Human epidermal growth factor receptor 2 (HER2) is the most crucial ErbB receptor tyrosine kinase (RTK) family member in HER2-positive (refered to HER2-overexpressing) breast cancer which are dependent on or "addictive" to the Phosphatidylinositol-3-kinase (PI3K) pathway. HER2-related target drugs trastuzumab and lapatinib have been the foundation of treatment of HER2--positive breast cancer. This study was designed to explore the relationship between PI3K pathway activation and the sensitivity to lapatinib in HER2--positive metastatic breast cancer patients pretreated with anthracyclins, taxanes and trastuzumab.

Methods

Sixty-seven HER2-positive metastatic breast cancer patients were recruited into a global lapatinib Expanded Access Program and 57 patients have primary tumor specimens available for determination of PI3K pathway status. PTEN status was determined by immunohistochemical staining and PIK3CA mutations were detected via PCR sequencing. All patients were treated with lapatinib 1250 mg/day continuously and capecitabine 1000 mg/m² twice daily on a 2-week-on and 1-week-off schedule until disease progression, death, withdrawal of informed consent, or intolerable toxicity.

Results

PIK3CA mutations and PTEN loss were detected in 12.3% (7/57) and 31.6% (18/57) of the patients, respectively. Twenty-two patients with PI3K pathway activation (defined as PIK3CA mutation and/or PTEN expression loss) had a lower clinical benefit rate (36.4% versus 68.6%, P = 0.017) and a lower overall response rate (9.1% versus 31.4%, P = 0.05), when compared with the 35 patients with no activation. A retrospective analysis of first trastuzumab-containing regimen treatment data showed that PI3K pathway activation correlated with a shorter median progression-free survival (4.5 versus 9.0 months, P = 0.013).

Conclusions

PIK3CA mutations occur more frequently in elder patients for HER2-positive breast cancer. PIK3CA mutations and PTEN loss are not mutually exclusive. PI3K pathway activation resulting from PTEN loss or PIK3CA mutations may lead to drug resistance to lapatinib and trastuzumab (http://ClinicalTrials.gov number, NCT00338247).

mTOR inhibition in breast cancer: unraveling the complex mechanisms of mTOR signal transduction and its clinical implications in therapy

INTRODUCTION

The mammalian target of rapamycin (mTOR)/PI3K/Akt pathway is altered in breast cancer cells, as demonstrated by mutations in both the upstream and downstream regulators of mTOR, including phosphatase and tensin homolog deleted in chromosome 10 (PTEN) loss or Akt/PI3K activation, and potentially in the mTOR protein itself. This contributes to increased cell proliferation, as well as growth-factor independence and endocrine resistance. Thus, mTOR inhibition holds considerable promise as a rational therapeutic strategy in breast cancer.

AREAS COVERED

This review describes how dysregulation of the mTOR pathway in breast cancer may contribute to breast cancer pathogenesis, as well as discussing preclinical and clinical data that support mTOR inhibitor therapy.

EXPERT OPINION

Direct blockade of the mTOR pathway is a new and intriguing area in breast cancer therapy, with the potential to modulate growth-factor and estrogen-dependent and -independent pathways, that contribute to the pathogenesis and progression of breast tumors. mTOR inhibitors demonstrate significant biologic activity with manageable toxicities, in combination with hormonal therapy and chemotherapy, in both the neoadjuvant and metastatic breast cancer settings.

The phosphatidyl inositol 3-kinase/AKT signaling pathway in breast cancer

The phosphatidyl inositol 3-kinase (PI3K)/Akt pathway mediates the effects of a variety of extracellular signals in a number of cellular processes including cell growth, proliferation, and survival. The alteration of integrants of this pathway through mutation of its coding genes increases the activation status of the signaling and can thus lead to cellular transformation. The frequent dysregulation of the PI3K/Akt pathway in breast cancer (BC) and the mediation of this pathway in different processes characteristically implicated in tumorigenesis have attracted the interest of this pathway in BC; however, a more comprehensive understanding of the signaling intricacies is necessary to develop clinical applications of the modulation of this pathway in this pathology. We review a series of experiments examining the contribution of alteration of integrants of this signaling network to human BC and we make an update of the information about the effect of the modulation of this pathway in this cancer.

miR-21 Expression in Pregnancy-Associated Breast Cancer: A Possible Marker of Poor Prognosis

Aims: microRNAs (miRNAs) are a class of small noncoding RNAs that can act as key modulators in tumorigenesis-related genes. Specifically, it has been suggested that miR-21 overexpression plays a role in the development and progression of breast cancer. So far, the role of miRNAs in pregnancy-associated breast cancer (PABC) has not been investigated.

Methods and Results: We evaluated miR-21 expression by quantitative RT-PCR in 35 patients, 25 with PABC and 10 control breast cancer cases not pregnancy-associated with similar clinicopathological features. We then analyzed protein expression for PTEN, BCL2 and PDCD4 as miR-21 target genes by IHC, and finally correlated the results with patients' clinicopathological features.

Significant overexpression of miR-21 in PABC tumors compared to normal adjacent tissue was found. Overexpression of miR-21 was frequently found in high grade tumors with loss of hormone receptor expression and was significantly associated with positive lymph nodes (p=0.025). In PABC patients, PTEN, BCL2 and PDCD4 target protein expression was decreased in 80%, 76% and 40% respectively.

Conclusion: Our study supports the involvement of miR-21 in breast cancer progression and metastasis formation in PABC implying a role of this miRNA as a marker for poor prognosis in PABC patients.

Clinical significance of tumor suppressor PTEN in colorectal carcinoma

BACKGROUND

It has been demonstrated that the deletion, mutation, hypermethylation and subcellular location of the tumor suppressor phosphatase and tensin homologue (PTEN) are closely correlated with carcinogenesis, progression and prognosis of malignancy. Both mutation and the microsatellite instability of the PTEN gene influence regulation of the PI3K/Akt signaling pathway. This study investigated whether loss of nuclear PTEN is correlated with chemosensitivity, clinicopathological parameters and survival.

METHODS

Intracellular levels of PTEN of multiple cell lines of colorectal carcinoma (CRC) were evaluated by Western blotting and immunocytochemistry. The chemosensitivity of cell lines with various expression levels of PTEN was evaluated using 5-flurouracil (5-FU), oxaliplatin and irinotecan (CPT), and clinical significance was evaluated by immunohistochemical analysis of 133 CRC specimens.

RESULTS

Colon cancer cell lines HT-29, LoVo and SW480 differed in expression of PTEN, with high, moderate and low levels, respectively. HT-29 and LoVo PTEN expression was suppressed by a low concentration of 5-FU and oxaliplatin; however, SW480 was insensitive to these chemotherapeutic agents. Nuclear PTEN was overexpressed in most (>80%) normal colon mucosa samples, but the incidence significantly decreased (89.2% → 53.4%) in the CRC group. PTEN in the nucleus was negatively correlated with tumor size and vascular invasion in CRC, and CRC patients with negative PTEN expression in the nucleus exhibited poor survival.

CONCLUSION

Cell lines with a high expression of PTEN are sensitive to chemotherapy with 5-FU and oxaliplatin. Nuclear PTEN expression gradually decreases after malignant transformation, and loss of PTEN expression in the nucleus is associated with tumor progression and poor clinical outcome in CRC.