Comparison of Akt/mTOR signaling in primary breast tumors and matched distant metastases

Loss of Hormone Receptor Expression after Exposure to Fluid Shear Stress in Breast Cancer Cell Lines

Following metastatic spread, many hormone receptor positive (HR+) patients develop a more aggressive phenotype with an observed loss of the HRs estrogen receptor (ER) and progesterone receptor (PR). During metastasis, breast cancer cells are exposed to high magnitudes of fluid shear stress (FSS). Unfortunately, the role for FSS on the regulation of HR expression and function during metastasis is not fully understood. This study was designed to elucidate the impact of FSS on HR+ breast cancer. Utilizing a microfluidic platform capable of exposing breast cancer cells to FSS that mimics in situ conditions, we demonstrate the impact of FSS exposure on representative HR+ breast cancer cell lines through protein and gene expression analysis. Proteomics results demonstrated that 540 total proteins and 1473 phospho-proteins significantly changed due to FSS exposure and pathways of interest included early and late estrogen response. The impact of FSS on response to 17β-estradiol (E2) was next evaluated and gene expression analysis revealed repression of ER and E2-mediated genes (PR and SDF1) following exposure to FSS. Western blot demonstrated enhanced phosphorylation of mTOR following exposure to FSS. Taken together, these studies provide initial insight into the effects of FSS on HR signaling in metastatic breast cancer.

Metabolic Signaling in Cancer Metastasis

Metastases, which are the leading cause of death in patients with cancer, have metabolic vulnerabilities. Alterations in metabolism fuel the energy and biosynthetic needs of metastases but are also needed to activate cell state switches in cells leading to invasion, migration, colonization, and outgrowth in distant organs. Specifically, metabolites can activate protein kinases as well as receptors and they are crucial substrates for posttranslational modifications on histone and nonhistone proteins. Moreover, metabolic enzymes can have moonlighting functions by acting catalytically, mainly as protein kinases, or noncatalytically through protein-protein interactions. Here, we summarize the current knowledge on metabolic signaling in cancer metastasis.

SIGNIFICANCE

Effective drugs for the prevention and treatment of metastases will have an immediate impact on patient survival. To overcome the current lack of such drugs, a better understanding of the molecular processes that are an Achilles heel in metastasizing cancer cells is needed. One emerging opportunity is the metabolic changes cancer cells need to undergo to successfully metastasize and grow in distant organs. Mechanistically, these metabolic changes not only fulfill energy and biomass demands, which are often in common between cancer and normal but fast proliferating cells, but also metabolic signaling which enables the cell state changes that are particularly important for the metastasizing cancer cells.

The tumor-nerve circuit in breast cancer

It is well established that innervation is one of the updated hallmarks of cancer and that psychological stress promotes the initiation and progression of cancer. The breast tumor environment includes not only fibroblasts, adipocytes, endothelial cells, and lymphocytes but also neurons, which is increasingly discovered important in breast cancer progression. Peripheral nerves, especially sympathetic, parasympathetic, and sensory nerves, have been reported to play important but different roles in breast cancer. However, their roles in the breast cancer progression and treatment are still controversial. In addition, the brain is one of the favorite sites of breast cancer metastasis. In this review, we first summarize the innervation of breast cancer and its mechanism in regulating cancer growth and metastasis. Next, we summarize the neural-related molecular markers in breast cancer diagnosis and treatment. In addition, we review drugs and emerging technologies used to block the interactions between nerves and breast cancer. Finally, we discuss future research directions in this field. In conclusion, the further research in breast cancer and its interactions with innervated neurons or neurotransmitters is promising in the clinical management of breast cancer.

Tea and Citrus maxima complex induces apoptosis of human liver cancer cells via PI3K/AKT/mTOR pathway in vitro

Objective

In this study, black tea and Citrus maxima (BT-CM), yellow tea and C. maxima (YT-CM), green tea and C. maxima (GT-CM) as subjects, the active ingredient content and antioxidant activity of three tea and C. maxima (T-CM) were analyzed. The effects of three T-CMs on apoptosis of liver cells in vitro and its mechanism were further explored.

Methods

National standard method and HPLC were used for active ingredient analysis. MTT, cell flow cytometry and Western blot were used to analyze the effects of three T-CMs on cell proliferation, apoptosis, and its underlying molecular mechanism.

Results

The content of tea polyphenols, free amino acids, ratio of polyphenols and amino acids, ester catechins, non-ester catechins and caffeine in YT-CM and GT-CM was significantly higher than that of BT-CM. The in vitro antioxidant capacity of YT-CM and GT-CM was also significantly stronger than that of BT-CM. Three T-CMs had the effects of inhibiting proliferation, arresting cell cycle and inducing apoptosis in HepG2 and Bel7402 cells, especially YT-CM and GT-CM. Western blot analysis showed three T-CMs activated PI3K/AKT/mTOR signaling pathway and regulated the expression levels of apoptosis-related proteins Bax, Bcl-2 and Caspase-3/9. YT-CM and GT-CM had better ability to change the signal pathway than BT-CM.

Conclusion

In short, T-CMs, which combined different degrees of fermentation tea with C. maxima, were rich in nutrients and biologically active substances. T-CMs, especially YT-CM and GT-CM, are healthy drinks that help to prevent and treat liver cancer.

Metformin suppresses breast cancer growth via inhibition of cyclooxygenase-2

Pre-clinical and on-going trials have indicated the advantage of using metformin as an anticancer drug alone or in combination with other chemotherapeutics for the treatment of patients with breast cancer. However, the mechanisms by which metformin attenuates tumorigenesis remain to be further elucidated. The present study investigated the anticancer effects of metformin in breast cancer and identified potential molecular targets of metformin using western blotting and immunohistochemical analysis. Metformin significantly decreased tumor cell proliferation in vitro and suppressed tumor growth in vivo. Moreover, it induced the activation of AMP-induced protein kinase and suppression of phosphorylated-eukaryotic translation initiation factor 4E-binding protein 1 (p-4E-BP1), a downstream effector of the mTOR signaling pathway, and decreased cyclin D1 levels in in vitro and in vivo experimental models. Additionally, metformin inhibited cyclooxygenase (COX)-2 expression. Clinically, high expression levels of COX-2 and p-4E-BP1 in tissues of patients with breast cancer were significantly associated with enhanced lymphatic metastasis and distant metastasis. Thus, the current data suggested that metformin may have potential value as a synergistic therapy targeting both the COX-2 and mTOR signaling pathways.

Second invasive breast cancers in patients treated with breast-conserving therapy

OBJECTIVE

Second breast cancers after breast-conserving therapy (BCT) include ipsilateral breast tumor recurrence (IBTR) and metachronous contralateral breast cancer (CBC). Each IBTR is further classified as true recurrence (TR) or new primary tumor (NP). We aim to compare survival outcomes of TR, NP and CBC, and explore the optimal treatments.

METHODS

168,427 patients with primary breast cancer who underwent BCT between 1990 and 2005 were identified in the SEER database. The risks of IBTR and CBC were estimated by annual hazard rate. The breast cancer-specific survival (BCSS) were assessed using multivariable Cox regression analysis.

RESULTS

With median follow-up of 13 years after BCT, 5413 patients developed an IBTR and 4050 patients had a CBC. The risk of IBTR peaked between 10 and 15 years after BCT, while the risk of CBC distributed evenly. 45.9% of IBTRs were classified as a TR and 54.1% as an NP. The time interval from primary breast cancer to NP was longer than to TR and CBC (P < 0.001). Patients with TR had a poorer BCSS than NP (P = 0.003) and CBC (P = 0.002). There was no difference in BCSS between mastectomy and repeat BCT for treating TR (P = 0.584) or NP (P = 0.243). The BCSS of CBCs treated with BCT was better than mastectomy (P = 0.010). Chemotherapy didn't improve the survival of patients with TR (P = 0.058). However, TRs with grade III or negative hormone receptors benefited from chemotherapy significantly.

CONCLUSION

Patients with TR had a poorer BCSS than NP and CBC. Classifying IBTR may provide clinical significance for treatments.

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.

Icariin enhances the chemosensitivity of cisplatin‑resistant ovarian cancer cells by suppressing autophagy via activation of the AKT/mTOR/ATG5 pathway

Icariin is a flavonoid derived from Epimedium sagittatum, and has a wide range of biological and pharmacological effects; however, little is known regarding its effect on drug‑resistant ovarian cancer and the signal transduction pathways underlying the regulation of apoptosis and autophagy. The present study aimed to investigate the re‑sensitization effects of icariin exerted on an ovarian cancer cell line. Autophagy was analyzed in a SKVCR cell line that had been treated with icariin. We investigated the sensitivity of SKVCR cells to cisplatin, as well as the effects of an autophagy agonist (rapamycin) on autophagy, apoptosis, and the protein kinase B (AKT) signaling pathway. Finally, the mechanism underlying the effects of autophagy‑related (ATG) protein ATG5 overexpression on autophagy, apoptosis and AKT signaling in SKVCR cells were determined. The results revealed that treatment with icariin inhibited cell viability and autophagy, but promoted G0/G1 phase cell cycle arrest and apoptosis as determined by Cell Counting Kit‑8, immunofluorescence and flow cytometry assays, respectively. Icariin reduced the resistance of SKVCR cells to cisplatin in vitro by inducing G1/S cell cycle transition, apoptosis and inhibiting autophagy. Furthermore, enhanced autophagy induced by rapamycin treatment or overexpression of ATG5 partially reversed the effect of icariin on cisplatin resistance and autophagy in SKVCR cells. At the molecular level, rapamycin treatment or overexpression of ATG5 reversed the effects of icariin on the expression of autophagy‑associated proteins, including microtubule‑associated protein 1 light chain 3β, Beclin‑1, ATG5 and p62, and the AKT/mammalian target of rapamycin (mTOR) pathway. Collectively, our results suggested that icariin enhances the chemosensitivity of SKVCR cells by suppressing autophagy via activation of the AKT/mTOR signaling pathway.

Exposure to nicotine-derived nitrosamine ketone and arecoline synergistically facilitates tumor aggressiveness via overexpression of epidermal growth factor receptor and its downstream signaling in head and neck squamous cell carcinoma

Long-term nicotine-derived nitrosamine ketone (NNK) and arecoline exposure promotes carcinogenesis and head and neck squamous cell carcinoma (HNSCC) progression, although most associated data on the two were analyzed individually. The molecular mechanisms underlying tumor progression associated with the synergistic effects of NNK and arecoline remain unclear. We treated SCC-25 and FaDu cells with NNK and arecoline (separately or in combination) for 3 months. Comparative analysis was performed to investigate the mechanism underlying the acquisition of properties related to tumor promotion, including stemness, anti-apoptosis, and resistance to HNSCC therapeutics. Long-term exposure to NNK and arecoline resulted in an increase in cancer stem cell properties, anti-apoptosis, and the resistance to cisplatin in HNSCC. We detected abundant epidermal growth factor receptor (EGFR) expression in HNSCC cells after combined treatment with NNK and arecoline. EGFR was pivotal in inducing tumor promotion and anti-apoptosis in cancer cells by inducing pAKT and NFκB. Combined treatment with NNK and arecoline synergistically facilitated tumor aggressiveness via EGFR–AKT signaling. Targeting EGFR–AKT signaling may be a feasible strategy for treating HNSCC.

ZKSCAN3 promotes breast cancer cell proliferation, migration and invasion

ZKSCAN3, a zinc-finger transcription factor, which has been shown to be upregulated in several human cancer. However, the expression level, function and mechanism of ZKSCAN3 in breast cancer remains unknown. In the current study, immunohistochemistry, western blot and quantitative real time polymerase chain reaction (qRT-PCR) results showed that ZKSCAN3 was overexpressed in breast cancer tissue compared with normal breast tissue. Through analyzing the clinicopathological characteristics, we demonstrated that positive ZKSCAN3 expression predicted poor prognosis of patients with breast cancer. The expression level of ZKSCAN3 protein/mRNA in breast cancer cells (MCF-7 and MDA-MB-231) was higher than its expression in normal breast cells (HBL-100). Knocking down ZKSCAN3 via its short hairpin RNA (shRNA) in MCF-7 and MDA-MB-231 inhibited cell viability, migration and invasion. Western blot analysis showed that ZKSCAN3 silencing lead to significant decreases in the expression of Cyclin D1, B-cell lymphoma-2 (Bcl-2), and matrix metalloproteinase (MMP)-2/MMP-9, as well as increases in the expression of Bcl2 Associated X Protein (Bax) in breast cancer cells. Additionally, ZKSCAN3-shRNA expression markedly suppressed tumor growth in breast cancer xenograft mice. Finally, we demonstrated that silencing of ZKSCAN3 was able to inhibit Akt/mTOR signaling pathway by blocking p-Akt and p-mTOR protein expression in breast cancer cells. These results demonstrate that ZKSCAN3 plays a significant role in the progression of breast cancer. Therefore, ZKSCAN3 is a potential therapeutic target for breast cancer.

Mechanism of resistance to endocrine therapy in breast cancer: the important role of PI3K/Akt/mTOR in estrogen receptor-positive, HER2-negative breast cancer

Endocrine therapy is a crucial treatment for estrogen receptor-positive (ER+) breast cancer, with proven clinical benefits. However, adaptive mechanisms emerge in the tumor, causing resistance to endocrine therapy. A better understanding of resistance mechanisms is needed to overcome this problem and to develop new, precise treatment strategies. Accumulating genetic and cancer biological studies demonstrate the importance of understanding the PI3K/Akt/mTOR and CDK4/6/RB pathways in ER+ HER2- breast cancer. PIK3CA (which encodes phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit α) is frequently mutated in breast cancer, and 30% of advanced ER+ HER2- breast cancers have an activating PIK3CA mutation. AKT1 mutations (E17K) have been found in 1.4-8% of breast cancer patients. ER+ breast cancer patients preferentially demonstrate gain of CCND1 (cyclin D1; 58% in luminal B vs. 29% in luminal A) and CDK4 (25% in luminal B vs. 14% in luminal A) and loss of CDKN2A (p16) and CDKN2C (p18), which are negatively regulated with the cell cycle and are correlated with the CDK4/6/RB pathway. Abnormalities in PI3K/Akt/mTOR and CDK4/6/RB pathways due to genetic alterations result in deregulated kinase activity and malignant transformation. This review focuses on the recent reports of the essential role of PI3K/Akt/mTOR and CDK4/6/RB pathways in ER+ HER2- breast cancer.

Molecular insights: Suppression of EGFR and AKT activation by a small molecule in non-small cell lung cancer

Epidermal growth factor receptor (EGFR) activation events and the mammalian target of rampamycin (mTOR) are considered important therapeutic targets in alleviating cancer conditions. The current treatment paradigm has shifted to personalized treatment strategies with tyrosine kinase inhibitors (TKIs) or anaplastic lymphoma kinase (ALK) inhibitors, due to low survival rates in non-small cell lung cancer (NSCLC) in terms of the prevailing platinum-based therapy. In the present study, we examined the anticancer potential of Verrucarin J (VJ), a small molecule, in NSCLC cell lines (H460 and A549). The small molecule significantly inhibited cell growth, proliferation, colony forming ability, and induced apoptosis in both lung cancer cell lines. The inhibitory effects on EGFR (pEGFR –tyr1173) and AKT (pAKT Serine473) signaling, downregulates downstream pro-survival signaling (mTOR and NF-κB) in cancer cell lines. In addition, VJ abrogated invasive and migratory potential of A549 and H460 cells. We also observed a downregulation of mesenchymal markers such as N-cadherin, Slug, β-catenin, and vimentin expression in both cell lines. Our results suggest that VJ inhibited cancer cell growth and could be a potent molecule to inhibit EGFR and AKT signaling in NSCLC.

Advances in the treatment of advanced oestrogen-receptor-positive breast cancer

Oestrogen-receptor-positive breast cancer is the most common subtype of breast cancer. Endocrine therapies that target the dependence of this subtype on the oestrogen receptor have substantial activity, yet the development of resistance to therapy is inevitable in advanced cancer. Major progress has been made in identifying the drivers of oestrogen-receptor-positive breast cancer and the mechanisms of resistance to endocrine therapy. This progress has translated into major advances in the treatment of advanced breast cancer, with several targeted therapies that enhance the efficacy of endocrine therapy; inhibitors of mTOR and inhibitors of the cyclin-dependent kinases CDK4 and CDK6 substantially improve progression-free survival. A new wave of targeted therapies is being developed, including inhibitors of PI3K, AKT, and HER2, and a new generation of oestrogen-receptor degraders. Considerable challenges remain in patient selection, deciding on the most appropriate order in which to administer therapies, and establishing whether cross-resistance occurs between therapies.

Resistance to mTORC1 Inhibitors in Cancer Therapy: From Kinase Mutations to Intratumoral Heterogeneity of Kinase Activity

Targeting mTORC1 has been thoroughly explored in cancer therapy. Following encouraging preclinical studies, mTORC1 inhibitors however failed to provide substantial benefits in cancer patients. Several resistance mechanisms have been identified including mutations of mTOR and activation of alternate proliferation pathways. Moreover, emerging evidence discloses intratumoral heterogeneity of mTORC1 activity that further contributes to a reduced anticancer efficacy of mTORC1 inhibitors. Genetic heterogeneity as well as heterogeneous conditions of the tumor environment such as hypoxia profoundly modifies mTORC1 activity in tumors and hence influences the response of tumors to mTORC1 inhibitors. Intriguingly, the heterogeneity of mTORC1 activity also occurs towards its substrates at the single cell level, as mutually exclusive pattern of activation of mTORC1 downstream effectors has been reported in tumors. After briefly describing mTORC1 biology and the use of mTORC1 inhibitors in patients, this review will give an overview on concepts of resistance to mTORC1 inhibition in cancer with a particular focus on intratumoral heterogeneity of mTORC1 activity.

The effect of JAK2 knockout on inhibition of liver tumor growth by inducing apoptosis, autophagy and anti-proliferation via STATs and PI3K/AKT signaling pathways

Liver cancer is a leading cause of cancer death, making it as the second most common cause for death from cancer globally. Though many studies before have explored a lot for liver cancer prevention and treatment, there are still a lot far from to know based on the molecular mechanisms. Janus kinase 2 (JAK2) has been reported to play an essential role in the progression of apoptosis, autophagy and proliferation for cells. Therefore, we were aimed to investigate the underlying mechanisms by which JAK2 performed its role in ameliorating liver cancer. JAK2 knockout liver cancer cell lines were involved for our experiments in vitro and in vivo. Western blotting, quantitative RT-PCR (qRT-PCR), ELISA, Immunohistochemistry, and flow-cytometric analysis were used to determine the key signaling pathway regulated by JAK2 for liver cancer progression. Data here indicated that JAK2, indeed, expressed highly in cancer cell lines compared to the normal liver cells. And apoptosis and autophagy were found in JAK2 knockout liver cancer cells through activating Caspase-3, Cyclin-D1 and mTOR regulated by STAT3/5 and PI3K/AKT signaling pathway. And also, the liver cancer cells proliferation was inhibited. In addition, tumor size and weight were reduced by knockout of JAK2 in vivo experiments. These findings demonstrated that JAK2 and its down-streaming signaling pathways play a direct role in the progression of liver cancer possibly. To our knowledge, it was the first time to evaluate the role of JAK2 knockout in improving liver cancer from apoptosis, autophagy and proliferation, which could be a potential target for future therapeutic approach clinically.

Epithelial to mesenchymal transition is associated with rapamycin resistance

Rapamycin analogues have antitumor efficacy in several tumor types, however few patients demonstrate tumor regression. Thus, there is a pressing need for markers of intrinsic response/resistance and rational combination therapies. We hypothesized that epithelial-to-mesenchymal transition (EMT) confers rapamycin resistance. We found that the epithelial marker E-cadherin protein is higher in rapamycin sensitive (RS) cells and mesenchymal breast cancer cell lines selected by transcriptional EMT signatures are less sensitive to rapamycin. MCF7 cells, transfected with constitutively active mutant Snail, had increased rapamycin resistance (RR) compared to cells transfected with wild-type Snail. Conversely, we transfected two RR mesenchymal cell lines-ACHN and MDA-MB-231-with miR-200b/c or ZEB1 siRNA to promote mesenchymal-to-epithelial transition. This induced E-cadherin expression in both cell lines, and ACHN demonstrated a significant increase in RS. Treatment of ACHN and MDA-MB-231 with trametinib modulated EMT in ACHN cells in vitro. Treatment of MDA-MB-231 and ACHN xenografts with trametinib in combination with rapamycin resulted in significant growth inhibition in both but without an apparent effect on EMT. Future studies are needed to determine whether EMT status is predictive of sensitivity to rapalogs and to determine whether combination therapy with EMT modulating agents can enhance antitumor effects of PI3K/mTOR inhibitors.

Prognostic significance of PD-L1 and PD-L2 in breast cancer

PD-L1 and PD-L2 constitute an important antitumor immune response. In breast cancer, their prognostic value is still to be defined. In this study, we investigate the correlation between PD-L1 and PD-L2 protein expressions with clinical and pathologic features and disease-free survival and overall survival. To assess PD-L1 and PD-L2 expressions, we conducted immunohistochemistry studies using a breast cancer tissue microarray encompassing a total of 192 breast cancer cases, stages I, II, and III, with detailed clinical and outcome data. PD-L1 expression was present in 56.6% (107/189), and PD-L2 expression was identified in 50.8% (97/191) of breast cancer cases. Younger age at diagnosis, lymph node positivity, negative estrogen receptor, and recurrence at distant sites were all associated with both PD-L1 and PD-L2 expressions. The presence of larger tumors was associated only with PD-L1 expression. In our study, PD-L1 expression was significantly associated with better overall survival (P = .04) in breast cancer patients. Despite its association with poor clinical and pathologic features, PD-L1 expression emerges as a positive prognostic biomarker in breast cancer. This survival result might be due to the presence of a strong antitumor immune response leading to PD-L1 expression.

Ability to Generate Patient-Derived Breast Cancer Xenografts Is Enhanced in Chemoresistant Disease and Predicts Poor Patient Outcomes

Background

Breast cancer patients who are resistant to neoadjuvant chemotherapy (NeoCT) have a poor prognosis. There is a pressing need to develop in vivo models of chemo resistant tumors to test novel therapeutics. We hypothesized that patient-derived breast cancer xenografts (BCXs) from chemo- naïve and chemotherapy-exposed tumors can provide high fidelity in vivo models for chemoresistant breast cancers.

Methods

Patient tumors and BCXs were characterized with short tandem repeat DNA fingerprinting, reverse phase protein arrays, molecular inversion probe arrays, and next generation sequencing.

Results

Forty-eight breast cancers (24 post-chemotherapy, 24 chemo-naïve) were implanted and 13 BCXs were established (27%). BCX engraftment was higher in TNBC compared to hormone-receptor positive cancer (53.8% vs. 15.6%, p = 0.02), in tumors from patients who received NeoCT (41.7% vs. 8.3%, p = 0.02), and in patients who had progressive disease on NeoCT (85.7% vs. 29.4%, p = 0.02). Twelve patients developed metastases after surgery; in five, BCXs developed before distant relapse. Patients whose tumors developed BCXs had a lower recurrence-free survival (p = 0.015) and overall survival (p<0.001). Genomic losses and gains could be detected in the BCX, and three models demonstrated a transformation to induce mouse tumors. However, overall, somatic mutation profiles including potential drivers were maintained upon implantation and serial passaging. One BCX model was cultured in vitro and re-implanted, maintaining its genomic profile.

Conclusions

BCXs can be established from clinically aggressive breast cancers, especially in TNBC patients with poor response to NeoCT. Future studies will determine the potential of in vivo models for identification of genotype-phenotype correlations and individualization of treatment.

Phase I study of the anti-IGF1R antibody cixutumumab with everolimus and octreotide in advanced well-differentiated neuroendocrine tumors

Preclinical data suggest multiple roles for the IGF1 receptor (IGF1R) in neuroendocrine tumors (NETs), including mediating resistance to mammalian target of rapamycin (mTOR) inhibitors. Everolimus, an oral mTOR inhibitor, and octreotide long-acting repeatable (LAR) are approved for subgroups of well-differentiated NET. The primary objective of the present study was to establish the safety and recommended phase II dose (RP2D) of cixutumumab, a monoclonal antibody (MAB) against IGF1R, with everolimus and octreotide LAR. Patients with well-differentiated NET were treated with 10  mg everolimus p.o. daily, 20  mg octreotide LAR i.m. every 21 days, and escalating doses of cixutumumab. An expansion cohort was enrolled at RP2D. Correlative studies included the evaluation of mTOR pathway inhibition in paired tumor biopsies and the effects of this combination on metabolism via indirect calorimetry. Nineteen patients with progressive disease were enrolled, including nine to the expansion portion. Two patients had dose-limiting toxicities of grade 3 mucositis at 15  mg/kg cixutumumab. Long-term tolerance at RP2D was problematic, and the most common ≥grade 3 adverse event was fatigue. One patient with metastatic insulinoma had a confirmed partial response, whereas 17 had stable disease. The median progression-free survival was 43.6 weeks, and the median overall survival was 25.5 months. The RP2D of this combination per the predefined study protocol of 10  mg/kg cixutumumab i.v., 20  mg octreotide LAR i.m. every 21 days plus 10  mg everolimus p.o. daily is associated with non-dose-limiting toxicities that limit long-term tolerance. Although a signal of activity was noted in the present study, this will need to be reconciled with limited tolerance of the combination and data from larger studies of anti-IGF1R MABs in NET that have been disappointing.

Immunohistochemical characterization of the mTOR pathway in stage-I non-small-cell lung carcinoma

BACKGROUND

Dysregulation of mammalian target of rapamycin (mTOR) pathway has been linked with malignant tumorigenesis. This study explored the expression profiles of proteins involved in the mTOR pathway and their relationships with clinicopathologic characteristics in stage-I non-small-cell lung carcinoma (NSCLC).

METHODS

The protein expression profiles of PTEN, p-Akt, p-mTOR, p-S6, and eIF4E were examined using immunohistochemical staining and tissue microarray method in 408 patients with stage-I NSCLC (250 adenocarcinomas [ADC] and 158 squamous cell carcinomas).

RESULTS

Retained PTEN expression (P<0.001), p-mTOR expression (P<0.001), and p-S6 expression (P=0.007) were associated with ADC histology. Expression of PTEN (P=0.001), p-Akt (P=0.005), p-mTOR (P=0.007), p-S6 (P<0.001) were correlated with lower pathologic T stage. PTEN loss was correlated with male gender and smoking history and p-mTOR expression was inversely correlated with these factors (P<0.001). Subgroup analysis of ADCs indicated that male gender, high pT stage, lymphovascular invasion, and PTEN loss were poor prognostic factors. Multivariate analysis revealed that the PTEN(-)/p-Akt(+)/p-mTOR(+) combination more effectively determined the prognosis of ADC (hazard ratio=2.2, P=0.004) than PTEN alone.

CONCLUSIONS

Activation of the mTOR pathway in early-stage ADCs suggests a significant role for the mTOR axis in early carcinogenesis. The combination of PTEN(-)/p-Akt(+)/p-mTOR(+) expression was correlated with poor overall survival in patients with stage-I lung ADC.

Everolimus plus exemestane for the treatment of advanced breast cancer: a review of subanalyses from BOLERO-2

Hormone receptor-positive breast cancer is typically managed with endocrine therapies. However, resistance to endocrine therapy results in disease progression in a large proportion of breast cancers. Through the understanding of the mechanisms of endocrine resistance, identification of implicated pathways and targets has led to the development of novel agents targeting these pathways. Phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway aberrations are common in breast cancer, with increased PI3K/AKT/mTOR signaling associated with resistance to endocrine and human epidermal growth factor receptor 2 (HER2)-targeted therapies. The mTOR inhibitor everolimus, in combination with exemestane, has been approved for patients with advanced hormone receptor-positive/HER2-negative breast cancer who progress on prior nonsteroidal aromatase inhibitor therapy based on results reported in the Breast Cancer Trials of Oral Everolimus-2 (BOLERO-2) study. This review will summarize the overall findings from BOLERO-2 and will consider available subanalyses by age, Asian origin, visceral or bone metastases, and prior therapy, with the aim of identifying populations most likely to benefit from everolimus therapy. The review will also summarize safety findings and their management and the effects of everolimus on quality of life.

Stand up to cancer phase Ib study of pan-phosphoinositide-3-kinase inhibitor buparlisib with letrozole in estrogen receptor-positive/human epidermal growth factor receptor 2-negative metastatic breast cancer

PURPOSE

Buparlisib, an oral reversible inhibitor of all class I phosphoinositide-3-kinases, has shown antitumoral activity against estrogen receptor (ER)-positive breast cancer cell lines and xenografts, alone and with endocrine therapy. This phase Ib study evaluated buparlisib plus letrozole's safety, tolerability, and preliminary activity in patients with metastatic ER-positive breast cancer refractory to endocrine therapy.

PATIENTS AND METHODS

Patients received letrozole and buparlisib in two different administration schedules. Outcomes were assessed by standard solid-tumor phase I methods. [(18)F]fluorodeoxyglucose-positron emission tomography/computed tomography ([(18)F]FDG-PET/CT) scans were done at baseline and 2 weeks after treatment initiation. Tumor blocks were collected for phosphoinositide-3-kinase pathway mutation analysis.

RESULTS

Fifty-one patients were allocated sequentially to continuous or intermittent (five on/two off days) buparlisib administration on an every-4-week schedule. Buparlisib's maximum-tolerated dose (MTD) was 100 mg/d. Common drug-related adverse events included ≤ grade 2 hyperglycemia, nausea, fatigue, transaminitis, and mood disorders. The clinical benefit rate (lack of progression ≥ 6 months) among all patients treated at the MTD was 31%, including two objective responses in the continuous dose arm. Of seven patients remaining on treatment ≥ 12 months, three had tumors with PIK3CA hot-spot mutation. Patients exhibiting metabolic disease progression by [(18)F]FDG-PET/CT scan at 2 weeks progressed rapidly on therapy.

CONCLUSION

The letrozole and buparlisib combination was safe, with reversible toxicities regardless of schedule administration. Clinical activity was observed independent of PIK3CA mutation status. No metabolic response by [(18)F]FDG-PET/CT scan at 2 weeks was associated with rapid disease progression. Phase III trials of buparlisib and endocrine therapy in patients with ER-positive breast cancer are ongoing.

PI3K/AKT/mTOR pathway activation in primary and corresponding metastatic breast tumors after adjuvant endocrine therapy

Both preclinical and clinical data suggest that activation of the PI3K/AKT/mTOR pathway in response to hormonal therapy results in acquired endocrine therapy resistance. We evaluated differences in activation of the PI3K/AKT/mTOR pathway in estrogen receptor α (ERα) positive primary and corresponding metastatic breast cancer tissues using immunohistochemistry for downstream activated proteins, like phosphorylated mTOR (p-mTOR), phosphorylated 4E Binding Protein 1 (p-4EBP1) and phosphorylated p70S6K (p-p70S6K). For p-mTOR and p-4EBP1, the proportion of immunostained tumor cells (0–100%) was scored. Cytoplasmic intensity (0–3) was assessed for p-p70S6K. The difference between expression of these activated PI3K/AKT/mTOR proteins- in primary and metastatic tumor was calculated and tested for an association with adjuvant endocrine therapy. In patients who had received endocrine therapy (N = 34), p-mTOR expression increased in metastatic tumor lesions compared to the primary tumor (median difference 45%), while in patients who had not received adjuvant endocrine therapy (N = 37), no difference was found. Similar results were observed for p-4EBP1 and p-p70S6K expression. In multivariate analyses, adjuvant endocrine therapy was significantly associated with an increase in p-mTOR (p = 0.01), p-4EBP1 (p = 0.03) and p-p70S6K (p = 0.001), indicating that compensatory activation of the PI3K/AKT/mTOR pathway might indeed be a clinically relevant resistance mechanism resulting in acquired endocrine therapy resistance.

Breast cancer metastasis: issues for the personalization of its prevention and treatment

Despite important progress in adjuvant and neoadjuvant therapies, metastatic disease often develops in breast cancer patients and remains the leading cause of their deaths. For patients with established metastatic disease, therapy is palliative, with few breaks and with mounting adverse effects. Many have hypothesized that a personalized or precision approach (the terms are used interchangeably) to cancer therapy, in which treatment is based on the individual characteristics of each patient, will provide better outcomes. Here, we discuss the molecular basis of breast cancer metastasis and the challenges in personalization of treatment. The instability of metastatic tumors remains a leading obstacle to personalization, because information from a patient's primary tumor may not accurately reflect the metastasis, and one metastasis may vary from another. Furthermore, the variable presence of tumor subpopulations, such as stem cells and dormant cells, may increase the complexity of the targeted treatments needed. Although molecular signatures and circulating biomarkers have been identified in breast cancer, there is lack of validated predictive molecular markers to optimize treatment choices for either prevention or treatment of metastatic disease. Finally, to maximize the information that can be obtained, increased attention to clinical trial design in the metastasis preventive setting is needed.

Activation of SNAT1/SLC38A1 in human breast cancer: correlation with p-Akt overexpression

BACKGROUND

SNAT1 is a subtype of the amino acid transport system A that has been implicated to play a potential role in cancer development and progression, yet its role in breast cancer remains unclear. In present study, we detected SNAT1 expression in breast cancers and explored its underlying mechanism in promoting breast carcinogenesis.

METHODS

RT-PCR and Western blotting were performed to analyze the transcription and protein levels of SNAT1 in breast cancer cell lines and fresh tissues. Tissue microarray blocks containing breast cancer specimens obtained from 210 patients were constructed. Expression of SNAT1 in these specimens was analyzed using immunohistochemical studies. SNAT1 was down-regulated by SNAT1-shRNA in breast cancer cells and the functional significance was measured.

RESULTS

SNAT1 was up-regulated in breast cancer cell lines and breast cancer tissues. Overexpression of SNAT1 was observed in 127 cases (60.5%). Expression of SNAT1 was significantly associated with tumor size, nodal metastasis, advanced disease stage, Ki-67, and ER status. Suppression of endogenous SNAT1 leads to cell growth inhibition, cell cycle arrest, and apoptosis of 4T1 cells and lowered the phosphorylation level of Akt. SNAT1 expression correlated significantly with p-Akt expression in human breast cancer samples.

CONCLUSIONS

The cross-talk between Akt signaling and SNAT1 might play a critical role in the development and progression of breast cancer, providing an important molecular basis for novel diagnostic markers and new attractive targets in the treatment of breast cancer patients.

PI3K/mTOR inhibition can impair tumor invasion and metastasis in vivo despite a lack of antiproliferative action in vitro: implications for targeted therapy

Oncogenic PI3K/mTOR activation is frequently observed in human cancers and activates cell motility via p27 phosphorylations at T157 and T198. Here we explored the potential for a novel PI3K/mTOR inhibitor to inhibit tumor invasion and metastasis. An MDA-MB-231 breast cancer line variant, MDA-MB-231-1833, with high metastatic bone tropism, was treated with a novel catalytic PI3K/mTOR inhibitor, PF-04691502, at nM doses that did not impair proliferation. Effects on tumor cell motility, invasion, p27 phosphorylation, localization, and bone metastatic outgrowth were assayed. MDA-MB-231-1833 showed increased PI3K/mTOR activation, high levels of cytoplasmic p27pT157pT198 and increased cell motility and invasion in vitro versus parental. PF-04691502 treatment, at a dose that did not affect proliferation, reduced total and cytoplasmic p27, decreased p27pT157pT198 and restored cell motility and invasion to levels seen in MDA-MB-231. p27 knockdown in MDA-MB-231-1833 phenocopied PI3K/mTOR inhibition, whilst overexpression of the phosphomimetic mutant p27T157DT198D caused resistance to the anti-invasive effects of PF-04691502. Pre-treatment of MDA-MB-231-1833 with PF-04691502 significantly impaired metastatic tumor formation in vivo, despite lack of antiproliferative effects in culture and little effect on primary orthotopic tumor growth. A further link between cytoplasmic p27 and metastasis was provided by a study of primary human breast cancers which showed cytoplasmic p27 is associated with increased lymph nodal metastasis and reduced survival. Novel PI3K/mTOR inhibitors may oppose tumor metastasis independent of their growth inhibitory effects, providing a rationale for clinical investigation of PI3K/mTOR inhibitors in settings to prevent micrometastasis. In primary human breast cancers, cytoplasmic p27 is associated with worse outcomes and increased nodal metastasis, and may prove useful as a marker of both PI3K/mTOR activation and PI3K/mTOR inhibitor efficacy.

Chemical Inhibitors and microRNAs (miRNA) Targeting the Mammalian Target of Rapamycin (mTOR) Pathway: Potential for Novel Anticancer Therapeutics

The mammalian target of rapamycin (mTOR) is a critical regulator of many fundamental features in response to upstream cellular signals, such as growth factors, energy, stress and nutrients, controlling cell growth, proliferation and metabolism through two complexes, mTORC1 and mTORC2. Dysregulation of mTOR signalling often occurs in a variety of human malignant diseases making it a crucial and validated target in the treatment of cancer. Tumour cells have shown high susceptibility to mTOR inhibitors. Rapamycin and its derivatives (rapalogs) have been tested in clinical trials in several tumour types and found to be effective as anticancer agents in patients with advanced cancers. To block mTOR function, they form a complex with FKBP12 and then bind the FRB domain of mTOR. Furthermore, a new generation of mTOR inhibitors targeting ATP-binding in the catalytic site of mTOR showed potent and more selective inhibition. More recently, microRNAs (miRNA) have emerged as modulators of biological pathways that are essential in cancer initiation, development and progression. Evidence collected to date shows that miRNAs may function as tumour suppressors or oncogenes in several human neoplasms. The mTOR pathway is a promising target by miRNAs for anticancer therapy. Extensive studies have indicated that regulation of the mTOR pathway by miRNAs plays a major role in cancer progression, indicating a novel way to investigate the tumorigenesis and therapy of cancer. Here, we summarize current findings of the role of mTOR inhibitors and miRNAs in carcinogenesis through targeting mTOR signalling pathways and determine their potential as novel anti-cancer therapeutics.

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

Introduction:

Somatostatin analogs (SSAs) are used as part of standard treatment for advanced neuroendocrine tumors (NETs). The mechanisms behind the antiproliferative action of SSAs remain largely unknown, but a connection with the mammalian target of rapamycin (mTOR) signaling pathway has been suggested. Our purpose was to evaluate the activation status of the AKT/mTOR pathway in advanced metastatic NETs and identify biomarkers of response to SSA therapy.

Patients and methods:

Expression of phosphatase and tensin homolog (PTEN), phosphorylated (p)-AKT(Ser473), and p-S6(Ser240/244) was evaluated using immunohistochemistry in archival paraffin samples from 23 patients. Expression levels were correlated with clinicopathological parameters and progression-free survival under treatment with SSAs.

Results:

A positive association between p-AKT and p-S6 expression was identified (P = 0.01) and higher expression of both markers was observed in pancreatic NETs. AKT/mTOR activation was observed without the loss of PTEN expression. Tumors showing AKT/mTOR signaling activation progressed faster when treated with SSAs: higher expression of p-AKT or p-S6 predicted a median progression-free survival of 1 month vs 26.5 months for lower expression (P = 0.02).

Conclusion:

Constitutive activation of the AKT/mTOR pathway was associated with shorter time-to-progression in patients undergoing treatment with SSAs. Larger case series are needed to validate whether p-AKT(Ser473) and p-S6(Ser240/244) can be used as prognostic markers of response to therapy with SSAs.

Heterogeneity between primary colon carcinoma and paired lymphatic and hepatic metastases

Heterogeneity is one of the recognized characteristics of human tumors, and occurs on multiple levels in a wide range of tumors. A number of studies have focused on the heterogeneity found in primary tumors and related metastases with the consideration that the evaluation of metastatic rather than primary sites could be of clinical relevance. Numerous studies have demonstrated particularly high rates of heterogeneity between primary colorectal tumors and their paired lymphatic and hepatic metastases. It has also been proposed that the heterogeneity between primary colon carcinomas and their paired lymphatic and hepatic metastases may result in different responses to anticancer therapies. The heterogeneity in primary colon carcinoma and corresponding metastases by genome‑wide gene expression analysis has not been extensively studied. In the present study, we investigated the differentially expressed genes between a primary colon carcinoma specimen (obtained from a 40-year-old female colon carcinoma patient with lymphatic and hepatic metastases) and its paired lymphatic and hepatic metastases by genome-wide gene expression analysis using GeneChip HGU133Plus2.0 expression arrays. Our results demonstrate that genome-wide gene expression varies between primary colon carcinoma and its paired lymphatic and hepatic metastases.

Analysis of whole genomic expression profiles and screening of the key signaling pathways associated with pancreatic cancer

The tumorigenesis of pancreatic cancer is thought to be a complex process. Investigation of the molecular mechanism of pancreatic cancer and exploring the specific markers for early diagnosis and specific targets of therapy is a key point to prevent and treat pancreatic cancer effectively and to improve their prognosis. In this study, expression profiles experiment was performed using Agilent human whole genomic oligonucleotide microarrays with 41,000 genes. Differentially expressed genes related with pancreatic cancer were screened, and analyzed further by GO term analysis and KEGG Pathway analysis. Our results showed that there were 1276 differentially expressed genes associated with pancreatic cancer. 691 genes were up regulated and 585 were down regulated in pancreatic cancer group. The present study confirmed that the occurrence of pancreatic cancer was involved in multiple-gene interaction. In addition, our study found that pancreatic cancer was related to an activation of the mTOR signaling pathway and renal cell carcinoma pathway.

PIK3CA/PTEN mutations and Akt activation as markers of sensitivity to allosteric mTOR inhibitors

PURPOSE

We sought to determine whether phosphoinositide 3-kinase (PI3K) pathway mutation or activation state and rapamycin-induced feedback loop activation of Akt is associated with rapamycin sensitivity or resistance.

EXPERIMENTAL DESIGN

Cancer cell lines were tested for rapamycin sensitivity, Akt phosphorylation, and mTOR target inhibition. Mice injected with breast or neuroendocrine cancer cells and patients with neuroendocrine tumor (NET) were treated with rapalogs and Akt phosphorylation was assessed.

RESULTS

Thirty-one cell lines were rapamycin sensitive (RS) and 12 were relatively rapamycin resistant (RR; IC(50) > 100 nmol/L). Cells with PIK3CA and/or PTEN mutations were more likely to be RS (P = 0.0123). Akt phosphorylation (S473 and T308) was significantly higher in RS cells (P < 0.0001). Rapamycin led to a significantly greater pathway inhibition and greater increase in p-Akt T308 (P < 0.0001) and p-Akt S473 (P = 0.0009) in RS cells. Rapamycin and everolimus significantly increased Akt phosphorylation but inhibited growth in an in vivo NET model (BON). In patients with NETs treated with everolimus and octreotide, progression-free survival correlated with p-Akt T308 in pretreatment (R = 0.4762, P = 0.0533) and on-treatment tumor biopsies (R = 0.6041, P = 0.0102). Patients who had a documented partial response were more likely to have an increase in p-Akt T308 with treatment compared with nonresponders (P = 0.0146).

CONCLUSION

PIK3CA/PTEN genomic aberrations and high p-Akt levels are associated with rapamycin sensitivity in vitro. Rapamycin-mediated Akt activation is greater in RS cells, with a similar observation in patients with clinical responses on exploratory biomarker analysis; thus feedback loop activation of Akt is not a marker of resistance but rather may function as an indicator of rapamycin activity.

Differential response to EGFR- and VEGF-targeted therapies in patient-derived tumor tissue xenograft models of colon carcinoma and related metastases

Heterogeneity in primary tumors and related metastases may result in failure of antitumor therapies, particularly in targeted therapies for the treatment of cancer. In this study, patient-derived tumor tissue (PDTT) xenograft models of colon carcinoma with lymphatic and hepatic metastases were used to evaluate the response to EGFR- and VEGF-targeted therapies. Our results showed that primary colon carcinoma and its corresponding lymphatic and hepatic metastases have a different response rate to anti-EGFR (cetuximab) and anti-VEGF (bevacizumab) therapies. However, the underlying mechanism of these types of phenomenon is still unclear. To investigate whether such phenomena may result from the heterogeneity in primary colon carcinoma and related metastases, we compared the expression levels of cell signaling pathway proteins using immunohistochemical staining and western blotting, and the gene status of KRAS using pyrosequencing in the same primary colon carcinoma and its corresponding lymphatic and hepatic metastatic tissues which were used for establishing the PDTT xenograft models. Our results showed that the expression levels of EGFR, VEGF, Akt/pAkt, ERK/pERK, MAPK/pMAPK, and mTOR/pmTOR were different in primary colon carcinoma and matched lymphatic and hepatic metastases although the KRAS gene status in all cases was wild-type. Our results indicate that the heterogeneity in primary colon carcinoma and its corresponding lymphatic and hepatic metastases may result in differences in the response to dual-inhibition of EGFR and VEGF.

Clinicopathological correlations of mTOR and pAkt expression in non-small cell lung cancer

The Akt/mammalian target of rapamycin (mTOR) pathway is up-regulated in many human cancers, and agents targeting the mTOR pathway are in various stages of clinical development and application. Expression of pAkt and mTOR was studied by immunohistochemical analysis of 574 surgically resected non-small cell lung cancer (NSCLC) specimens on a tissue microarray. The results were correlated with clinicopathological features. Expression of mTOR showed a strong correlation with the expression of pAkt (p < 0.001) and was significantly associated with female gender, tumor size of ≤3 cm, adenocarcinoma (ADC), non-smoker status, and lower pathological stage. Expression of pAkt was correlated with older age (≥65), ADC, non-smoker status, and lower T stage. Univariate survival analysis revealed that the mTOR- and pAkt-positive group had a significantly longer cancer-specific survival than the mTOR- and pAkt-negative group (p = 0.038 and 0.024, respectively). Coexpression of pAkt and mTOR correlated with better prognosis than either single- or double-negative pAkt and mTOR groups (p = 0.016). However, multivariate analysis proved that mTOR and pAkt expression are not independent prognostic factors for cancer-specific survival. Expression of pAkt and mTOR expression is more significantly associated with ADC than squamous cell carcinoma. Although pAkt/mTOR expression is not an independent prognostic marker, expression of these proteins is associated with better prognosis.

Genetic variation in genes involved in hormones, inflammation and energetic factors and breast cancer risk in an admixed population

Breast cancer incidence rates are characterized by unique racial and ethnic differences. Native American ancestry has been associated with reduced breast cancer risk. We explore the biological basis of disparities in breast cancer risk in Hispanic and non-Hispanic white women by evaluating genetic variation in genes involved in inflammation, insulin and energy homeostasis in conjunction with genetic ancestry. Hispanic (2111 cases, 2597 controls) and non-Hispanic white (1481 cases, 1586 controls) women enrolled in the 4-Corner's Breast Cancer Study, the Mexico Breast Cancer Study and the San Francisco Bay Area Breast Cancer Study were included. Genetic admixture was determined from 104 ancestral informative markers that discriminate between European and Native American ancestry. Twenty-one genes in the CHIEF candidate pathway were evaluated. Higher Native American ancestry was associated with reduced risk of breast cancer (odds ratio = 0.79, 95% confidence interval 0.65, 0.95) but was limited to postmenopausal women (odds ratio = 0.66, 95% confidence interval 0.52, 0.85). After adjusting for genetic ancestry and multiple comparisons, four genes were significantly associated with breast cancer risk, NFκB1, NFκB1A, PTEN and STK11. Within admixture strata, breast cancer risk among women with low Native American ancestry was associated with IkBKB, NFκB1, PTEN and RPS6KA2, whereas among women with high Native American ancestry, breast cancer risk was associated with IkBKB, mTOR, PDK2, PRKAA1, RPS6KA2 and TSC1. Higher Native American ancestry was associated with reduced breast cancer risk. Breast cancer risk differed by genetic ancestry along with genetic variation in genes involved in inflammation, insulin, and energy homeostasis.

Assessment of a novel VEGF targeted agent using patient-derived tumor tissue xenograft models of colon carcinoma with lymphatic and hepatic metastases

The lack of appropriate tumor models of primary tumors and corresponding metastases that can reliably predict for response to anticancer agents remains a major deficiency in the clinical practice of cancer therapy. It was the aim of our study to establish patient-derived tumor tissue (PDTT) xenograft models of colon carcinoma with lymphatic and hepatic metastases useful for testing of novel molecularly targeted agents. PDTT of primary colon carcinoma, lymphatic and hepatic metastases were used to create xenograft models. Hematoxylin and eosin staining, immunohistochemical staining, genome-wide gene expression analysis, pyrosequencing, qRT-PCR, and western blotting were used to determine the biological stability of the xenografts during serial transplantation compared with the original tumor tissues. Early passages of the PDTT xenograft models of primary colon carcinoma, lymphatic and hepatic metastases revealed a high degree of similarity with the original clinical tumor samples with regard to histology, immunohistochemistry, genes expression, and mutation status as well as mRNA expression. After we have ascertained that these xenografts models retained similar histopathological features and molecular signatures as the original tumors, drug sensitivities of the xenografts to a novel VEGF targeted agent, FP3 was evaluated. In this study, PDTT xenograft models of colon carcinoma with lymphatic and hepatic metastasis have been successfully established. They provide appropriate models for testing of novel molecularly targeted agents.

Phosphatidylinositol 3-kinase pathway activation in breast cancer brain metastases

INTRODUCTION

Activation status of the phosphatidylinositol 3-kinase (PI3K) pathway in breast cancer brain metastases (BCBMs) is largely unknown. We examined expression of phospho(p)-AKT, p-S6, and phosphatase and tensin homologue (PTEN) in BCBMs and their implications for overall survival (OS) and survival after BCBMs. Secondary analyses included PI3K pathway activation status and associations with time to distant recurrence (TTDR) and time to BCBMs. Similar analyses were also conducted among the subset of patients with triple-negative BCBMs.

METHODS

p-AKT, p-S6, and PTEN expression was assessed with immunohistochemistry in 52 BCBMs and 12 matched primary BCs. Subtypes were defined as hormone receptor (HR)+/HER2-, HER2+, and triple-negative (TNBC). Survival analyses were performed by using a Cox model, and survival curves were estimated with the Kaplan-Meier method.

RESULTS

Expression of p-AKT and p-S6 and lack of PTEN (PTEN-) was observed in 75%, 69%, and 25% of BCBMs. Concordance between primary BCs and matched BCBMs was 67% for p-AKT, 58% for p-S6, and 83% for PTEN. PTEN- was more common in TNBC compared with HR+/HER2- and HER2+. Expression of p-AKT, p-S6, and PTEN- was not associated with OS or survival after BCBMs (all, P > 0.06). Interestingly, among all patients, PTEN- correlated with shorter time to distant and brain recurrence. Among patients with TNBC, PTEN- in BCBMs was associated with poorer overall survival.

CONCLUSIONS

The PI3K pathway is active in most BCBMs regardless of subtype. Inhibition of this pathway represents a promising therapeutic strategy for patients with BCBMs, a group of patients with poor prognosis and limited systemic therapeutic options. Although expression of the PI3K pathway did not correlate with OS and survival after BCBM, PTEN- association with time to recurrence and OS (among patients with TNBC) is worthy of further study.

Targeting PI3K/mTOR signaling in cancer

The American Association for Cancer Research (AACR) Special Conference on Targeting PI3K/mTOR Signaling in Cancer was held in San Francisco, California from February 24 to 27, 2011. The meeting was cochaired by Drs. Lewis C. Cantley, David M. Sabatini, and Funda Meric-Bernstam. The main focus of this event was the therapeutic potential of drugs targeting the PI3K/mTOR signaling pathway for the treatment of cancer. This article summarizes the recent discoveries in the field, with particular emphasis on the major themes of the conference.

pS6 Expression in normal renal parenchyma, primary renal cell carcinomas and their metastases

In cancer therapy novel concepts focus on phosphoinositide-3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) inhibitors. In this context, phosphorylated S6 protein of the 40S ribosomal subunit (pS6) overexpression was previously shown to be associated with sensitivity to inhibitors of mTOR. The present study therefore evaluated pS6 expression in normal renal parenchyma (NRP), primary renal cell carcinomas (PRCC) and their metastases. pS6 and pmTOR expression was immunohistochemically analyzed in a tissue microarray (TMA) from localized primary renal cell carcinoma (lPRCC) (n = 35), metastasized primary renal cell carcinoma (mPRCC) (n = 45), their metastases (n = 45), and NRP (n = 45). pS6 expression was stronger in mPRCCs and metastases than in NRP and lPRCCs (p < 0.05). In mPRCCs high-grade and high-stage tumors showed higher pS6 levels. pS6 overexpression was more frequently found in metastases (40/45; 88.9%) than in mPRCC (24/45; 53.3%) (p < 0.05). Overexpression of pS6 in metastases without concomitant overexpression in their primary tumors was found in 16/45 (35.56%) cases. Patients with pS6 overexpression in mPRCCs but also in metastases showed a tendency to shorter overall survival. pS6 score and pmTOR score correlated positively in NRP and in tumorous tissue (mPRCC and metastases). In conclusion, the present study showed stronger pS6 expression and more frequent overexpression in metastases than in corresponding PRCCs. In approximately one-third of the cases pS6 overexpression was found exclusively in metastases, which is interesting with regard to the association between high pS6 expression and sensitivity to mTOR inhibitor therapy.

Expression of p-AKT and p-mTOR in a large series of bronchopulmonary neuroendocrine tumors

Bronchopulmonary neuroendocrine tumors (BP-NETs) are separated into four subgroups: typical carcinoid tumor (TC), atypical carcinoid tumor (AC), large-cell neuroendocrine carcinoma (LCNEC) and small-cell lung carcinoma (SCLC). The signaling pathway involving AKT/mammalian target of rapamycin (mTOR) is crucial to the regulation of cell growth, proliferation and survival, and is frequently activated in human cancers. Consequently, mTOR is considered an attractive target for anticancer agents. The present study aimed to evaluate the expression of phosphorylated AKT and mTOR in a series of BP-NETs, and to analyze the correlations with clinicopathological parameters. p-AKT and p-mTOR levels were determined by immunohistochemistry in a series of 210 BP-NETs, including 85 SCLCs, 17 LCNECs, 26 ACs, 75 TCs and 7 tumorlets. Higher p-AKT and p-mTOR expression levels were identified in the majority of tumorlets and carcinoids in comparison to the LCNECs (P=0.0001) and SCLCs (P=0.0002). Furthermore, a significant association was observed between p-mTOR expression and tumor size (T) in SCLCs (P=0.04) and LCNECs (P=0.03): T3-T4 tumors exhibited significantly lower p-mTOR expression compared to T1-T2 tumors. In conclusion, most of the BP-NETs examined in this study expressed p-AKT and p-mTOR, suggesting that the AKT/mTOR pathway plays an important role in these tumors. Additionally, our results confirm that low- to intermediate-grade tumors are more closely associated to each other than to high-grade tumors, despite sharing common classification and a common origin from neuroendocrine cells. These findings improve our knowledge of the biological characterization of these tumors and indicate new therapeutic opportunities for the treatment of BP-NETs.

PI3K pathway mutations and PTEN levels in primary and metastatic breast cancer

The purpose of this work was to determine whether there are differences in PIK3CA mutation status and PTEN protein expression between primary and matched metastatic breast tumors as this could influence patient management. Paraffin sections of 50 μm were used for DNA extraction and slides of 3 μm for immunohistochemistry (IHC) and FISH. Estrogen receptor, progesterone receptor, and HER2 IHC were repeated in a central laboratory for both primary tumors and metastases. PTEN levels were assessed by IHC and phosphoinositide 3-kinase (PI3K) pathway mutations were detected by a mass spectroscopy-based approach. Median age was 48 years (range: 30-83 years). Tumor subtype included 72% hormone receptor positive/HER2 negative, 20% HER2-positive, and less than 7.8% triple receptor negative. Tissues were available for PTEN IHC in 46 primary tumors and 52 metastases. PTEN was lost in 14 (30%) primary tumors and 13 (25%) metastases. There were five cases of PTEN loss and eight cases of PTEN gain from primary tumors to metastases (26% discordance). Adequate DNA was obtained from 46 primary tumors and from 50 metastases for PIK3CA analysis. PIK3CA mutations were detected in 19 (40%) of primary tumors and 21 (42%) of metastases. There were five cases of PIK3CA mutation loss and four cases of mutation gain (18% discordance). There was an increase of the level of PIK3CA mutations in four cases and decrease in one case from primary tumors to metastases. There is a high level of discordance in PTEN level, PIK3CA mutations, and receptor status between primary tumors and metastases that may influence patient selection and response to PI3K-targeted therapies.

Classification of ipsilateral breast tumor recurrences after breast conservation therapy can predict patient prognosis and facilitate treatment planning

OBJECTIVE

To classify ipsilateral breast tumor recurrences (IBTR) as either new primary tumors (NP) or true local recurrence (TR). We utilized 2 different methods and compared sensitivities and specificities between them. Our goal was to determine whether distinguishing NP from TR had prognostic value.

BACKGROUND

After breast-conservation therapy, IBTR may be classified into 2 distinct types (NP and TR). Studies have attempted to classify IBTR by using tumor location, histologic subtype, DNA flow cytometry data, or gene-expression profiling data.

METHODS

A total of 447 (7.9%) of 5660 patients undergoing breast-conservation therapy from 1970 to 2005 experienced IBTR. Clinical data from 397 patients were available for review. We classified IBTRs as NP or TR on the basis of either tumor location and histologic subtype (method 1) or tumor location, histologic subtype, estrogen receptor status and human epidermal growth factor receptor 2 status (method 2). Kaplan-Meier curves and log-rank tests were used to evaluate overall and disease-specific survival differences between the 2 groups. Classification methods were validated by calculating sensitivity and specificity values using a Bayesian method.

RESULTS

Of 397 patients, 196 (49.4%) were classified as NP by method 1 and 212 (53.4%) were classified as NP by method 2. The sensitivity and specificity values were 0.812 and 0.867 for method 1 and 0.870 and 0.800 for method 2, respectively. Regardless of method used, patients classified as NP developed contralateral breast carcinoma more often but had better 10-year overall and disease-specific survival rates than those classified as TR. Patients with TR were more likely to develop metastatic disease after IBTR.

CONCLUSION

Ipsilateral breast tumor recurrences classified as TR and NP had clinically different features, suggesting that classifying IBTR may provide clinically significant data for the management of IBTR.

Mammalian target of rapamycin: biological function and target for novel anticancer agents

PURPOSE

The biological function of the mammalian target of rapamycin (mTOR) and mechanisms of action of mTOR inhibitors currently available for clinical use are described.

SUMMARY

mTOR is a target for anticancer agents due to its role in cancer development, progression, and resistance to other antineoplastic agents. Currently, two mTOR inhibitors, temsirolimus and everolimus, are approved for the treatment of patients with advanced renal cell carcinoma (RCC). Clinical trials comparing single-agent temsirolimus with interferon alfa-2a demonstrated an improvement in overall survival and progression-free survival (PFS) in patients with metastatic RCC. Clinical studies comparing everolimus with placebo indicated improved PFS in advanced RCC patients whose disease had progressed on or after vascular endothelial growth factor (VEGF) inhibitor therapy. Due to its role in the phosphatidylinositol 3-kinase (PI3K) signaling pathway, mTOR is a rational target for inhibition in combination with other agents, including traditional chemotherapy and agents that are affected by or target the PI3K pathway. Data from these studies review the use of mTOR inhibitors in non-Hodgkin's lymphoma and endometrial, breast, and neuroendocrine tumors. Common toxicities of mTOR inhibitors include mucositis, stomatitis, rash, asthenia, fatigue, and myelosuppression. Additional toxicities requiring monitoring include hyperglycemia, hyperlipidemia, and pneumonitis.

CONCLUSION

The mTOR signaling pathway is upregulated in a variety of solid and hematologic tumors. Two inhibitors of this pathway, temsirolimus and everolimus, have been approved for use in metastatic RCC. Although relatively safe, these drugs are associated with some unique adverse effects, such as hyperlipidemia, hyperglycemia, and pneumonitis, that require monitoring and may require clinical intervention.

Heterogeneity in primary tumors and corresponding metastases: could it provide us with any hints to personalize cancer therapy?

Interpatient variability in response to anticancer drugs is associated with different clinical outcomes, which is partially owing to the individual differences among patients. Many investigators have hoped that tumor heterogeneity would help to reveal the underlying mechanism of interpatient variability in response to anticancer therapy. Numerous studies have demonstrated the presence of intratumor heterogeneity and the heterogeneity in primary tumors and corresponding metastases in a wide range of tumors at different levels and have indicated that the heterogeneity might make sense as a potential determinant of anticancer therapy response. This article discusses tumor heterogeneity, focusing on the heterogeneity in primary tumors and corresponding metastases as well as the effect on anticancer therapy response. Furthermore, an idea of tumor-site-based personalized cancer therapy for patients with metastatic malignancies was hypothesized, and a strategy using a patient-derived tumor tissue xenograft model to realize this idea is also proposed in this article.

Deciphering the role of PI3K/Akt/mTOR pathway in breast cancer biology and pathogenesis

The phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway mediates multiple cellular functions critical to tumor initiation, progression, and outcomes, including growth and proliferation, metabolism, motility, migration, invasion, angiogenesis, survival, and autophagy. Tight regulation of this pathway is paramount to ensure that multiple cellular inputs are integrated for appropriate cellular outcomes. Frequent deregulation and aberrations of this pathway have been implicated in breast cancer development and progression. This review focuses on the biology of this pathway and its role in breast cancer pathogenesis. The role of therapies directed at targeting mTOR in the PI3K/Akt/mTOR pathway, which are currently being evaluated in clinical trials, will also be reviewed.

p-AKT overexpression in primary renal cell carcinomas and their metastases

In cancer therapy novel concepts focus on phosphoinositide 3-kinase (PI3K)/activated protein kinase B (p-AKT)/mammalian target of rapamycin (mTOR) inhibitors. In this context, p-AKT overexpression was previously shown to be associated with sensitivity to inhibitors of mTOR. The present study evaluated p-AKT expression in a tissue microarray of primary renal cell carcinomas (PRCCs) (n = 45), their metastases (primary onset n = 45, secondary onset n = 5), and normal renal parenchyma (n = 45) by means of immunohistochemistry. Total p-AKT overexpression was found in 24/45 (53.3%) PRCCs, in 32/45 (71.1%) primary and in 3/5 (60%) secondary onset metastases. Membranous p-AKT overexpression was seen more frequently in PRCCs, namely 11/45 (24.4%), than in primary onset metastases 1/45 (2.2%). Overexpression of total p-AKT solely in metastases without overexpression in PRCC was exclusively demonstrated in primary onset metastases, namely in 28.9%. Patients with total p-AKT overexpression in primary carcinomas showed a trend to longer, and those with total p-AKT overexpression in metastases a tendency to shorter survival. In conclusion, the present study shows total p-AKT overexpression to be more frequent in metastases than in PRCCs. Total p-AKT overexpression in metastases without concomitant overexpression in their primary tumors was found in approximately one-third of primary onset metastases, which is interesting with regard to the association between high p-AKT expression and sensitivity to mTOR inhibitor therapy.

PI3K pathway activation in breast cancer is associated with the basal-like phenotype and cancer-specific mortality

Breast cancer is a common malignancy with current biological therapies tailored to steroid hormone (ER, PR) and HER2 receptor status. Understanding the biological basis of resistance to current targeted therapies and the identification of new potential therapeutic targets is an ongoing challenge. The PI3K pathway is altered in a high proportion of breast cancers and may contribute to therapeutic resistance. We undertook an integrative study of mutational, copy number and expression analyses of key regulators of the PI3K pathway in a cohort of 292 invasive breast cancer patients with known treatment outcomes. The alterations identified in this cohort included PIK3CA mutations (12/168, i.e. 7%), PIK3CA copy number gain (28/209, i.e. 14%), PTEN loss (73/258, i.e. 28%) and AKT activation (62/258, i.e. 24%). Overall at least 1 parameter was altered in 72% (139/193) of primary breast cancers. PI3K pathway activation was significantly associated with ER negative (p = 0.0008) and PR negative (p = 0.006) status, high tumor grade (p = 0.032) and a "basal-like" phenotype (p = 0.01), where 92% (25/27) of tumors had an altered pathway. In univariate analysis, PI3K pathway aberrations were associated with death from breast cancer; however, this relationship was not maintained in multivariate analysis. No association was identified between an activated pathway and outcome in tamoxifen- or chemotherapy-treated patients. We concluded that >70% of breast cancers have an alteration in at least 1 component of the PI3K pathway and this might be exploited to therapeutic advantage especially in "basal-like" cancers.

The regulation of protein synthesis in cancer

Translational control of cancer is a multifaceted process, involving alterations in translation factor levels and activities that are unique to the different types of cancers and the different stages of disease. Translational alterations in cancer include adaptations of the tumor itself, of the tumor microenvironment, an integral component in disease, and adaptations that occur as cancer progresses from development to local disease and ultimately to metastatic disease. Adaptations include the overexpression and increased activity of specific translation factors, the physical or functional loss of translation regulatory components, increased production of ribosomes, selective mRNA translation, and alteration of signal transduction pathways to permit unfettered activation of protein synthesis. There is intense clinical interest to capitalize on the emerging new understanding of translational control in cancer by targeting specific components of the translation apparatus that are altered in disease for the development of specific cancer therapeutics. Clinical trial data are nascent but encouraging, suggesting that translational control constitutes an important new area for drug development in human cancer.

Targeting the mTOR signaling network for cancer therapy

The serine-threonine kinase mammalian target of rapamycin (mTOR) plays a major role in the regulation of protein translation, cell growth, and metabolism. Alterations of the mTOR signaling pathway are common in cancer, and thus mTOR is being actively pursued as a therapeutic target. Rapamycin and its analogs (rapalogs) have proven effective as anticancer agents in a broad range of preclinical models. Clinical trials using rapalogs have demonstrated important clinical benefits in several cancer types; however, objective response rates achieved with single-agent therapy have been modest. Rapalogs may be more effective in combination with other anticancer agents, including chemotherapy and targeted therapies. It is increasingly apparent that the mTOR signaling network is quite complex, and rapamycin treatment leads to different signaling responses in different cell types. A better understanding of mTOR signaling, the mechanism of action of rapamycin, and the identification of biomarkers of response will lead to more optimal targeting of this pathway for cancer therapy.