Mechanism of Akt1 inhibition of breast cancer cell invasion reveals a protumorigenic role for TSC2

The dual role of the TSC complex in cancer

The tuberous sclerosis complex (TSC1/TSC2/TBC1D7) primarily functions to inhibit the mechanistic target of rapamycin complex 1 (mTORC1), a crucial regulator of cell growth. Mutations in TSC1 or TSC2 cause tuberous sclerosis complex (TSC), a rare autosomal dominant genetic disorder marked by benign tumors in multiple organs that rarely progress to malignancy. Traditionally, TSC proteins are considered tumor suppressive due to their inhibition of mTORC1 and other mechanisms. However, more recent studies have shown that TSC proteins can also promote tumorigenesis in certain cancer types. In this review, we explore the composition and function of the TSC protein complex, the roles of its individual components in cancer biology, and potential future therapeutic targeting strategies.

Protein Tyrosine Phosphatase 1B (PTP1B): A Comprehensive Review of Its Role in Pathogenesis of Human Diseases

Overexpression of protein tyrosine phosphatase 1B (PTP1B) disrupts signaling pathways and results in numerous human diseases. In particular, its involvement has been well documented in the pathogenesis of metabolic disorders (diabetes mellitus type I and type II, fatty liver disease, and obesity); neurodegenerative diseases (Alzheimer's disease, Parkinson's disease); major depressive disorder; calcific aortic valve disease; as well as several cancer types. Given this multitude of therapeutic applications, shortly after identification of PTP1B and its role, the pursuit to introduce safe and selective enzyme inhibitors began. Regrettably, efforts undertaken so far have proved unsuccessful, since all proposed PTP1B inhibitors failed, or are yet to complete, clinical trials. Intending to aid introduction of the new generation of PTP1B inhibitors, this work collects and organizes the current state of the art. In particular, this review intends to elucidate intricate relations between numerous diseases associated with the overexpression of PTP1B, as we believe that it is of the utmost significance to establish and follow a brand-new holistic approach in the treatment of interconnected conditions. With this in mind, this comprehensive review aims to validate the PTP1B enzyme as a promising molecular target, and to reinforce future research in this direction.

Thiazolyl-isatin derivatives: Synthesis, in silico studies, in vitro biological profile against breast cancer cells, mRNA expression, P-gp modulation, and interactions of Akt2 and VIM proteins

The literature reports that thiazole and isatin nuclei present a range of biological activities, with an emphasis on anticancer activity. Therefore, our proposal was to make a series of compounds using the molecular hybridization strategy, which has been used by our research group, producing hybrid molecules containing the thiazole and isatin nuclei. After structural planning and synthesis, the compounds were characterized and evaluated in vitro against breast cancer cell lines (T-47D, MCF-7 and MDA-MB-231) and against normal cells (PBMC). The activity profile on membrane proteins involved in chemoresistance and tumorigenic signaling proteins was also evaluated. Among the compounds tested, the compounds 4c and 4a stood out with IC50 values of 1.23 and 1.39 μM, respectively, against the MDA-MB-231 cell line. Both compounds exhibited IC50 values of 0.45 μM for the MCF-7 cell line. Compounds 4a and 4c significantly decreased P-gp mRNA expression levels in MCF-7, 4 and 2 folds respectively. Regarding the impact on tumorigenic signaling proteins, compound 4a inhibited Akt2 in MDA-MB-231 and compound 4c inhibited the mRNA expression of VIM in MCF-7.

Role of Akt/Protein Kinase B in Cancer Metastasis

Metastasis is a critical step in the process of carcinogenesis and a vast majority of cancer-related mortalities result from metastatic disease that is resistant to current therapies. Cell migration and invasion are the first steps of the metastasis process, which mainly occurs by two important biological mechanisms, i.e., cytoskeletal remodelling and epithelial to mesenchymal transition (EMT). Akt (also known as protein kinase B) is a central signalling molecule of the PI3K-Akt signalling pathway. Aberrant activation of this pathway has been identified in a wide range of cancers. Several studies have revealed that Akt actively engages with the migratory process in motile cells, including metastatic cancer cells. The downstream signalling mechanism of Akt in cell migration depends upon the tumour type, sites, and intracellular localisation of activated Akt. In this review, we focus on the role of Akt in the regulation of two events that control cell migration and invasion in various cancers including head and neck squamous cell carcinoma (HNSCC) and the status of PI3K-Akt pathway inhibitors in clinical trials in metastatic cancers.

Clinical and Genomic Characteristics of Patients with Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative Metastatic Breast Cancer Following Progression on Cyclin-Dependent Kinase 4 and 6 Inhibitors

PURPOSE

We explored the clinical and genomic characteristics of hormone receptor-positive (HR+), HER2-negative (HER2-) metastatic breast cancer (MBC) after progression on cyclin-dependent kinase 4 and 6 inhibitors (CDK4 and 6i) ± endocrine therapy (ET) to understand potential resistance mechanisms that may aid in identifying treatment options.

EXPERIMENTAL DESIGN

Patients in the United States with HR+, HER2- MBC had tumor biopsies collected from a metastatic site during routine care following progression on a CDK4 and 6i ± ET (CohortPost) or prior to initiating CDK4 and 6i treatment (CohortPre) and analyzed using a targeted mutation panel and RNA-sequencing. Clinical and genomic characteristics were described.

RESULTS

The mean age at MBC diagnosis was 59 years in CohortPre (n = 133) and 56 years in CohortPost (n = 223); 14% and 45% of patients had prior chemotherapy/ET, and 35% and 26% had de novo stage IV MBC, respectively. The most common biopsy site was liver (CohortPre, 23%; CohortPost, 56%). CohortPost had significantly higher tumor mutational burden (TMB; median 3.16 vs. 1.67 Mut/Mb, P < 0.0001), ESR1 alteration frequency (mutations: 37% vs. 10%, FDR < 0.0001; fusions: 9% vs. 2%, P = 0.0176), and higher copy-number amplification of genes on chr12q15, including MDM2, FRS2, and YEATS4 versus patients in the CohortPre group. In addition, CDK4 copy-number gain on chr12q13 was significantly higher in CohortPost versus CohortPre (27% vs. 11%, P = 0.0005).

CONCLUSIONS

Distinct mechanisms potentially associated with resistance to CDK4 and 6i ± ET, including alterations in ESR1 and amplification of chr12q15 and CDK4 copy-number gain, were identified.

AKT1 Transcriptomic Landscape in Breast Cancer Cells

Overexpression and hyperactivation of the serine/threonine protein kinase B (AKT) pathway is one of the most common cellular events in breast cancer progression. However, the nature of AKT1-specific genome-wide transcriptomic alterations in breast cancer cells and breast cancer remains unknown to this point. Here, we delineate the impact of selective AKT1 knock down using gene-specific siRNAs or inhibiting the AKT activity with a pan-AKT inhibitor VIII on the nature of transcriptomic changes in breast cancer cells using the genome-wide RNA-sequencing analysis. We found that changes in the cellular levels of AKT1 lead to changes in the levels of a set of differentially expressed genes and, in turn, imply resulting AKT1 cellular functions. In addition to an expected positive relationship between the status of AKT1 and co-expressed cellular genes, our study unexpectedly discovered an inherent role of AKT1 in inhibiting the expression of a subset of genes in both unstimulated and growth factor stimulated breast cancer cells. We found that depletion of AKT1 leads to upregulation of a subset of genes—many of which are also found to be downregulated in breast tumors with elevated high AKT1 as well as upregulated in breast tumors with no detectable AKT expression. Representative experimental validation studies in two breast cancer cell lines showed a reasonable concurrence between the expression data from the RNA-sequencing and qRT-PCR or data from ex vivo inhibition of AKT1 activity in cancer patient-derived cells. In brief, findings presented here provide a resource for further understanding of AKT1-dependent modulation of gene expression in breast cancer cells and broaden the scope and significance of AKT1 targets and their functions.

AKT1 mediates multiple phosphorylation events that functionally promote HSF1 activation

The heat stress response activates the transcription factor heat shock factor 1 (HSF1), which subsequently upregulates heat shock proteins to maintain the integrity of the proteome. HSF1 activation requires nuclear localization, trimerization, DNA binding, phosphorylation and gene transactivation. Phosphorylation at S326 is an important regulator of HSF1 transcriptional activity. Phosphorylation at S326 is mediated by AKT1, mTOR, p38, MEK1 and DYRK2. Here, we observed activation of HSF1 by AKT1 independently of mTOR. AKT2 also phosphorylated S326 of HSF1 but showed weak ability to activate HSF1. Similarly, mTOR, p38, MEK1 and DYRK2 all phosphorylated S326 but AKT1 was the most potent activator. Mass spectrometry showed that AKT1 also phosphorylated HSF1 at T142, S230 and T527 in addition to S326, whereas the other kinases did not. Subsequent investigation revealed that phosphorylation at T142 is necessary for HSF1 trimerization and that S230, S326 and T527 are required for HSF1 gene transactivation and recruitment of TFIIB and CDK9. Interestingly, T527 as a phosphorylated residue has not been previously shown and sits in the transactivation domain, further implying a role for this site in HSF1 gene transactivation. This study suggests that HSF1 hyperphosphorylation is targeted and these specific residues have direct function in regulating HSF1 transcriptional activity.

Analysis of the effects of aryl hydrocarbon receptor expression on cancer cell invasion via three-dimensional microfluidic invasion assays

The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that binds to xenobiotics and activates expression of response elements to metabolize these compounds. The AHR pathway has been associated with a long list of diseases including cancer; however, it is debated whether AHR is tumorigenic or tumour-inhibiting. In particular, there are contradictory reports in the literature regarding the effects of AHR expression level on metastatic breast cancer. Here we used a 3D invasion assay called cell invasion in digital microfluidic microgel systems (CIMMS) to study the effect of AHR expression on invasion. In this study, MDA-MB-231 cells with stable knockout of AHR (AHRko) showed enhanced invasive characteristics and reduced proliferation, and cells with transient overexpression of AHR showed reduced invasiveness. Overexpression of AHR with a mutation in the DNA binding domain showed no difference in invasiveness compared to control, which suggests that the changes in invasiveness are related to the expression of AHR. CIMMS also allowed for extraction of sub-populations of invaded cells for RNA sequencing experiments. A comparison of the transcriptomes of invaded subpopulations of wild-type and AHRko cells identified 1809 genes that were differentially expressed, with enriched pathways including cell cycle, proliferation, survival, immunoproteasome activation, and activation of matrix metalloproteases. In sum, the data reported here for MDA-MB-231 cells suggests some new interpretations of the discrepancy in the literature on the role of AHR in breast cancer. We propose that the unique combination of functional discrimination with transcriptome profiling provided by CIMMS will be valuable for a wide range of mechanistic invasion-biology studies in the future.

The Adipokine Component in the Molecular Regulation of Cancer Cell Survival, Proliferation and Metastasis

A hormonal imbalance may disrupt the rigorously monitored cellular microenvironment by hampering the natural homeostatic mechanisms. The most common example of such hormonal glitch could be seen in obesity where the uprise in adipokine levels is in virtue of the expanding bulk of adipose tissue. Such aberrant endocrine signaling disrupts the regulation of cellular fate, rendering the cells to live in a tumor supportive microenvironment. Previously, it was believed that the adipokines support cancer proliferation and metastasis with no direct involvement in neoplastic transformations and tumorigenesis. However, the recent studies have reported discrete mechanisms that establish the direct involvement of adipokine signaling in tumorigenesis. Moreover, the individual adipokine profile of the patients has never been considered in the prognosis and staging of the disease. Hence, the present manuscript has focused on the reported extensive mechanisms that culminate the basis of poor prognosis and diminished survival rate in obese cancer patients.

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.

Sevoflurane Modulates AKT Isoforms in Triple Negative Breast Cancer Cells. An Experimental Study

(1) Background: Triple negative breast cancer (TNBC) is a highly aggressive tumor, associated with high rates of early distant recurrence and short survival times, and treatment may require surgery, and thus anesthesia. The effects of anesthetic drugs on cancer progression are under scrutiny, but published data are controversial, and the involved mechanisms unclear. Anesthetic agents have been shown to modulate several molecular cascades, including PI3K/AKT/mTOR. AKT isoforms are frequently amplified in various malignant tumors and associated with malignant cell survival, proliferation and invasion. Their activation is often observed in human cancers and is associated with decreased survival rate. Certain anesthetics are known to affect hypoxia cell signaling mechanisms by upregulating hypoxia-inducible factors (HIFs). (2) Methods: MCF-10A and MDA-MB 231 cells were cultivated and CellTiter-Blue^® Cell Viability assay, 2D and 3D matrigel assay, immunofluorescence assays and gene expressions assay were performed after exposure to different sevoflurane concentrations. (3) Results: Sevoflurane exposure of TNBC cells results in morphological and behavioral changes. Sevoflurane differently influences the AKT isoforms expression in a time-dependent manner, with an important early AKT3 upregulation. The most significant effects occur at 72 h after 2 mM sevoflurane treatment and consist in increased viability, proliferation and aggressiveness and increased vimentin and HIF expression. (4) Conclusions: Sevoflurane exposure during surgery may contribute to cancer recurrence via AKT3 induced epithelial–mesenchymal transition (EMT) and by all three AKT isoforms enhanced cancer cell survival and proliferation.

AKT3 is a key regulator of head and neck squamous cell carcinoma

The phosphatidylinositol 3‐kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway plays a vital role in cell proliferation, apoptosis, metabolism, and angiogenesis in various human cancers, including head and neck squamous cell carcinoma (HNSCC). In the present study, we aimed to clarify the role of AKT, which is a major downstream effector of the PI3K‐AKT‐mTOR pathway, in HNSCC. We first investigated the mRNA expression of AKT isoforms using RNA‐sequencing data from The Cancer Genome Atlas database. We observed a specific elevation of AKT3 expression in HNSCC tissues when compared with that in normal tissues. Furthermore, AKT3 expression correlated with genes related to the immunosuppressive microenvironment more than the other AKT isoforms and PIK3CA. Accordingly, we focused on AKT3 and performed a knockdown approach using an HNSCC cell line. AKT3 knockdown cells exhibited impaired proliferation, a shift in the cell cycle from G2/M to G1/G0 phase, an increase in apoptotic cells, and downregulation of gene expression related to immunosuppression, as well as the knockdown of its upstream regulator PIK3CA. We also performed immunohistochemistry for both AKT3 and PIK3CA using surgical specimens from 72 patients with HNSCC. AKT3 expression in tumor cells correlated with immune cell infiltration and unfavorable prognosis when compared with PIK3CA. These findings suggested that AKT3 expression is a potential biomarker for predicting the immunoreactivity and prognosis of HNSCC. Furthermore, the isoform‐specific inhibition of AKT3 could be developed as a novel cancer therapy that efficiently suppresses the PI3K‐AKT‐mTOR pathway.

Combined inhibition of ACK1 and AKT shows potential toward targeted therapy against KRAS-mutant non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) with Kirsten RAt Sarcoma 2 viral oncogene homolog (KRAS) mutation has become a clinical challenge in cancer treatment as KRAS-mutant tumors are often resistant to conventional anti-tumor therapies. Activated CDC42-associated kinase 1 (ACK1), an activator of protein kinase B (AKT), is a promising target for KRAS-mutant tumor therapy, but the downstream ACK1 signaling remains poorly understood. The aim of this study was to evaluate the effectiveness of combined ACK1/AKT inhibition on the proliferation, migration, invasion, and apoptosis of KRAS-mutant NSCLC cell lines (NCI-H23, NCI-H358, and A549). The cells were treated with an inhibitor of either ACK1 (dasatinib or sunitinib) or AKT (MK-2206 or GDC-0068), and the optimal concentrations of the two yielding synergistic tumor-killing effects were determined by applying the Chou-Talalay equation for drug combinations. We showed that combined administration of ACK1 and AKT inhibitors at the optimal concentrations effectively suppressed NSCLC cell viability and promoted apoptosis while inducing cell cycle arrest at the G2 phase. Moreover, NSCLC cell migration and invasion were inhibited by combined ACK1/AKT inhibition. These phenomena were associated with the reduced phosphorylation levels of ACK1 and AKT (at Ser473 and Thr308), as well as alterations in caspase-dependent apoptotic signaling. Collectively, our results demonstrate the promising therapeutic potential of combined ACK1/AKT inhibition as a strategy against KRAS-mutant NSCLC. Our findings provide the basis for the clinical translation of biological targeted drugs (ACK1 and AKT inhibitors) and their rational combination in cancer treatment.

Methyl-Donors Can Induce Apoptosis and Attenuate Both the Akt and the Erk1/2 Mediated Proliferation Pathways in Breast and Lung Cancer Cell Lines

Dietary methyl-donors play important roles in physiological processes catalyzed by B vitamins as coenzymes, and are used for complementary support in oncotherapy. Our hypothesis was that methyl-donors can not only assist in tolerating cancer treatment but may also directly interfere with tumor growth and proliferation. Therefore, we investigated the proposed cancer inhibitory effects of methyl-donors (in a mixture of L-methionine, choline chloride, folic acid, and vitamin B12) on MCF7 and T47D breast cancer as well as A549 and H1650 lung cancer cell lines. Indeed, methyl-donor treatment significantly reduced the proliferation in all cell lines, possibly through the downregulation of MAPK/ERK and AKT signaling. These were accompanied by the upregulation of the pro-apoptotic Bak and Bax, both in MCF7 and H1650 cells, at reduced anti-apoptotic Mcl-1 and Bcl-2 levels in MCF7 and H1650 cells, respectively. The treatment-induced downregulation of p-p53(Thr55) was likely to contribute to protecting the nuclear localization and apoptosis inducing functions of p53. The presented features are known to improve the sensitivity of cancer therapy. Therefore, these data support the hypothesis, i.e., that methyl-donors may promote apoptotic signaling by protecting p53 functions through downregulating both the MAPK/ERK and the AKT pathways both in breast and lung adenocarcinoma cell lines. Our results can emphasize the importance and benefits of the appropriate dietary supports in cancer treatments. However, further studies are required to confirm these effects without any adverse outcome in clinical settings.

Knockdown of AKT3 Activates HER2 and DDR Kinases in Bone-Seeking Breast Cancer Cells, Promotes Metastasis In Vivo and Attenuates the TGFβ/CTGF Axis

Bone metastases frequently occur in breast cancer patients and lack appropriate treatment options. Hence, understanding the molecular mechanisms involved in the multistep process of breast cancer bone metastasis and tumor-induced osteolysis is of paramount interest. The serine/threonine kinase AKT plays a crucial role in breast cancer bone metastasis but the effect of individual AKT isoforms remains unclear. Therefore, AKT isoform-specific knockdowns were generated on the bone-seeking MDA-MB-231 BO subline and the effect on proliferation, migration, invasion, and chemotaxis was analyzed by live-cell imaging. Kinome profiling and Western blot analysis of the TGFβ/CTGF axis were conducted and metastasis was evaluated by intracardiac inoculation of tumor cells into NOD scid gamma (NSG) mice. MDA-MB-231 BO cells exhibited an elevated AKT3 kinase activity in vitro and responded to combined treatment with AKT- and mTOR-inhibitors. Knockdown of AKT3 significantly increased migration, invasion, and chemotaxis in vitro and metastasis to bone but did not significantly enhance osteolysis. Furthermore, knockdown of AKT3 increased the activity and phosphorylation of pro-metastatic HER2 and DDR1/2 but lowered protein levels of CTGF after TGFβ-stimulation, an axis involved in tumor-induced osteolysis. We demonstrated that AKT3 plays a crucial role in bone-seeking breast cancer cells by promoting metastatic potential without facilitating tumor-induced osteolysis.

AKT1 E17K Inhibits Cancer Cell Migration by Abrogating β-Catenin Signaling

Mutational activation of the PI3K/AKT pathway is among the most common pro-oncogenic events in human cancers. The clinical utility of PI3K and AKT inhibitors has, however, been modest to date. Here, we used CRISPR-mediated gene editing to study the biological consequences of AKT1 E17K mutation by developing an AKT1 E17K-mutant isogenic system in a TP53-null background. AKT1 E17K expression under the control of its endogenous promoter enhanced cell growth and colony formation, but had a paradoxical inhibitory effect on cell migration and invasion. The mechanistic basis by which activated AKT1 inhibited cell migration and invasion was increased E-cadherin expression mediated by suppression of ZEB1 transcription via altered β-catenin subcellular localization. This phenotypic effect was AKT1-specific, as AKT2 activation had the opposite effect, a reduction in E-cadherin expression. Consistent with the opposing effects of AKT1 and AKT2 activation on E-cadherin expression, a pro-migratory effect of AKT1 activation was not observed in breast cancer cells with PTEN loss or expression of an activating PIK3CA mutation, alterations which induce the activation of both AKT isoforms. The results suggest that the use of AKT inhibitors in patients with breast cancer could paradoxically accelerate metastatic progression in some genetic contexts and may explain the frequent coselection for CDH1 mutations in AKT1-mutated breast tumors. IMPLICATIONS: AKT1 E17K mutation in breast cancer impairs migration/invasiveness via sequestration of β-catenin to the cell membrane leading to decreased ZEB1 transcription, resulting in increased E-cadherin expression and a reversal of epithelial-mesenchymal transition.

Influence of ARHGAP29 on the Invasion of Mesenchymal-Transformed Breast Cancer Cells

Aggressive and mesenchymal-transformed breast cancer cells show high expression levels of Rho GTPase activating protein 29 (ARHGAP29), a negative regulator of RhoA. ARHGAP29 was the only one of 32 GTPase-activating enzymes whose expression significantly increased after the induction of mesenchymal transformation in breast cancer cells. Therefore, we investigated the influence of ARHGAP29 on the invasiveness of aggressive and mesenchymal-transformed breast cancer cells. After knock-down of ARHGAP29 using siRNA, invasion of HCC1806, MCF-7-EMT, and T-47D-EMT breast cancer cells was significantly reduced. This could be explained by reduced inhibition of RhoA and a consequent increase in stress fiber formation. Proliferation of the breast cancer cell line T-47D-EMT was slightly increased by reduced expression of ARHGAP29, whereas that of HCC1806 and MCF-7-EMT significantly increased. Using interaction analyses we found that AKT1 is a possible interaction partner of ARHGAP29. Therefore, the expression of AKT1 after siRNA knock-down of ARHGAP29 was tested. Reduced ARHGAP29 expression was accompanied by significantly reduced AKT1 expression. However, the ratio of active pAKT1 to total AKT1 remained unchanged or was significantly increased after ARHGAP29 knock-down. Our results show that ARHGAP29 could be an important factor in the invasion of aggressive and mesenchymal-transformed breast cancer cells. Further research is required to fully understand the underlying mechanisms.

PTEN and Other PtdIns(3,4,5)P3 Lipid Phosphatases in Breast Cancer

The phosphoinositide 3-kinase (PI3K)/AKT signalling pathway is hyperactivated in ~70% of breast cancers. Class I PI3K generates PtdIns(3,4,5)P₃ at the plasma membrane in response to growth factor stimulation, leading to AKT activation to drive cell proliferation, survival and migration. PTEN negatively regulates PI3K/AKT signalling by dephosphorylating PtdIns(3,4,5)P₃ to form PtdIns(4,5)P₂. PtdIns(3,4,5)P₃ can also be hydrolysed by the inositol polyphosphate 5-phosphatases (5-phosphatases) to produce PtdIns(3,4)P₂. Interestingly, while PTEN is a bona fide tumour suppressor and is frequently mutated/lost in breast cancer, 5-phosphatases such as PIPP, SHIP2 and SYNJ2, have demonstrated more diverse roles in regulating mammary tumourigenesis. Reduced PIPP expression is associated with triple negative breast cancers and reduced relapse-free and overall survival. Although PIPP depletion enhances AKT phosphorylation and supports tumour growth, this also inhibits cell migration and metastasis in vivo, in a breast cancer oncogene-driven murine model. Paradoxically, SHIP2 and SYNJ2 are increased in primary breast tumours, which correlates with invasive disease and reduced survival. SHIP2 or SYNJ2 overexpression promotes breast tumourigenesis via AKT-dependent and independent mechanisms. This review will discuss how PTEN, PIPP, SHIP2 and SYNJ2 distinctly regulate multiple functional targets, and the mechanisms by which dysregulation of these distinct phosphoinositide phosphatases differentially affect breast cancer progression.

Akt isoform-specific effects on thyroid cancer development and progression in a murine thyroid cancer model

The Akt family is comprised of three unique homologous proteins with isoform-specific effects, but isoform-specific in vivo data are limited in follicular thyroid cancer (FTC), a PI3 kinase-driven tumor. Prior studies demonstrated that PI3K/Akt signaling is important in thyroid hormone receptor βPV/PV knock-in (PV) mice that develop metastatic thyroid cancer that most closely resembles FTC. To determine the roles of Akt isoforms in this model we crossed Akt1-/-, Akt2-/-, and Akt3-/- mice with PV mice. Over 12 months, thyroid size was reduced for the Akt null crosses (p < 0.001). Thyroid cancer development and local invasion were delayed in only the PVPV-Akt1 knock out (KO) mice in association with increased apoptosis with no change in proliferation. Primary-cultured PVPV-Akt1KO thyrocytes uniquely displayed a reduced cell motility. In contrast, loss of any Akt isoform reduced lung metastasis while vascular invasion was reduced with Akt1 or 3 loss. Microarray of thyroid RNA displayed incomplete overlap between the Akt KO models. The most upregulated gene was the dendritic cell (DC) marker CD209a only in PVPV-Akt1KO thyroids. Immunohistochemistry demonstrated an increase in CD209a-expressing cells in the PVPV-Akt1KO thyroids. In summary, Akt isoforms exhibit common and differential functions that regulate local and metastatic progression in this model of thyroid cancer.

RAGE Up-Regulation Differently Affects Cell Proliferation and Migration in Pancreatic Cancer Cells

The receptor for advanced glycation end products (RAGE) contributes to many cellular aspects of pancreatic cancer including cell proliferation, migration, and survival. Studies have shown that RAGE activation by its ligands promotes pancreatic tumor growth by stimulating both cell proliferation and migration. In this study, we investigated the effect of RAGE up-regulation on the proliferation and migration of the human pancreatic cancer Panc-1 cell-line. We show that moderate overexpression of RAGE in Panc-1 cells results in increased cell proliferation, but decreased cell migration. The observed cellular changes were confirmed to be RAGE-specific and reversible by using RAGE-specific siRNAs and the small molecule RAGE inhibitor FPS-ZM1. At the molecular level, we show that RAGE up-regulation was associated with decreased activity of FAK, Akt, Erk1/2, and NF-κB signaling pathways and greatly reduced levels of α2 and β1 integrin expression, which is in agreement with the observed decreases in cell migration. We also demonstrate that RAGE up-regulation changes the expression of key molecular markers of epithelial-to-mesenchymal transition (EMT). Our results suggest that in the absence of stimulation by external ligands, RAGE up-regulation can differently modulate cell proliferation and migration in pancreatic cancer cells and regulates partly EMT.

Stromal SNAI2 Is Required for ERBB2 Breast Cancer Progression

SNAI2 overexpression appears to be associated with poor prognosis in breast cancer, yet it remains unclear in which breast cancer subtypes this occurs. Here we show that excess SNAI2 is associated with a poor prognosis of luminal B HER2⁺/ERBB2⁺ breast cancers in which SNAI2 expression in the stroma but not the epithelium correlates with tumor proliferation. To determine how stromal SNAI2 might influence HER2⁺ tumor behavior, Snai2-deficient mice were crossed with a mouse line carrying the ErbB2/Neu protooncogene to generate HER2⁺/ERBB2⁺ breast cancer. Tumors generated in this model expressed SNAI2 in the stroma but not the epithelium, allowing for the role of stromal SNAI2 to be studied without interference from the epithelial compartment. The absence of SNAI2 in the stroma of HER2⁺/ERBB2⁺ tumors is associated with: (i) lower levels of cyclin D1 (CCND1) and reduced tumor epithelium proliferation; (ii) higher levels of AKT and a lower incidence of metastasis; (iii) lower levels of angiopoietin-2 (ANGPT2), and more necrosis. Together, these results indicate that the loss of SNAI2 in cancer-associated fibroblasts limits the production of some cytokines, which influences AKT/ERK tumor signaling and subsequent proliferative and metastatic capacity of ERBB2⁺ breast cancer cells. Accordingly, SNAI2 expression in the stroma enhanced the tumorigenicity of luminal B HER2⁺/ERBB2⁺ breast cancers. This work emphasizes the importance of stromal SNAI2 in breast cancer progression and patients' prognosis. SIGNIFICANCE: Stromal SNAI2 expression enhances the tumorigenicity of luminal B HER2⁺ breast cancers and can identify a subset of patients with poor prognosis, making SNAI2 a potential therapeutic target for this disease. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/23/5216/F1.large.jpg.

Molecular dynamics simulation, free energy landscape and binding free energy computations in exploration the anti-invasive activity of amygdalin against metastasis

BACKGROUND AND OBJECTIVE

Historically, amygdalin has been used as alternative medicine or in vitro and in vivo studies, but no single study exists which discusses the structural mechanism of amygdalin at a molecular level. This paper inquiries into the inhibitory actions of amygdalin on the selected targets: AKT1, FAK, and ILK, which are regulators for various mediated signaling pathways, and are associated with cell adhesion, migration, and differentiation. In order to get details at the molecular level of amygdalin's inhibitory activities against chosen proteins, molecular modeling and simulation techniques including double docking, molecular dynamics simulation, free energy landscape analysis, and binding free energy calculation were exerted.

METHODS

To get molecular level details of amygdalin inhibitory effects against the relevant proteins; here the utilized tools are the following: the double docking, molecular dynamics simulation, free energy landscape analysis, g_mmpbsa, and interaction entropy were used to evaluate the inhibitory activity against targeted proteins.

RESULTS

The computational calculations revealed that amygdalin inhibits the selected targets via block the ATP-binding pocket of AKT1, FAK, and ILK by forming stable hydrogen bonds. Moreover, free energy landscape, FEL exposed that amygdalin stabilized the global conformations of both FAK and ILK proteins to the minimum global energy besides it reduced the essential dynamics of FAK and ILK proteins. MMPBSA computations provided further evidence for amygdalin's stability inside the ATP-binding pocket of AKT1, FAK, and ILK with a binding free energy of 45.067, -13.033, 13.109 kJ/mol, respectively. The binding free energies are lastly consistent with the hydrogen bonding and pairs within 0.35 nm results. The decomposition of binding energy shows the pivotal amino acid residues responsible for the stability of amygdalin's interactions inside the ATP-binding sites by forming hydrogen bonds.

CONCLUSIONS

Before this work, it was enigmatic to make predictions about how amygdalin inhibits metastasis of cancer. But the computational results contribute in several ways to our understanding of amygdalin activity and provide a basic insight into the activity of amygdalin as a multi-target drug in the metastasis and invasion of cancer.

Long non-coding RNAs lnc-ANGPTL1-3:3 and lnc-GJA10-12:1 present as regulators of sentinel lymph node metastasis in breast cancer

Long non-coding RNAs (lncRNAs) participate in various biological processed involved in tumorigenesis, metastasis and proliferation. The aim of the present study was to identify candidate long non-coding RNAs (lncRNAs) involved in sentinel lymph node (SLN) metastasis in breast cancer. Specimens of SLNs were collected from patients with SLN metastasis via punch biopsy. Total RNA was extracted and RNA sequencing (RNA-seq) was conducted. Differential expression profiles of mRNAs and lncRNAs were obtained via bioinformatics analysis, and Gene Oncology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed on differentially expressed mRNAs. The expression levels of lncRNAs were analyzed via reverse transcription-quantitative PCR (RT-qPCR), and the regulation network of the lncRNAs to downstream microRNAs (miRs) and mRNAs was predicted. Based on RNA-seq results, six differentially expressed candidate lncRNAs were identified in patients with and without SLN metastasis: lnc-ANGPTL1-3:3, lnc-GJA10-12:1, lnc-ACAN-2:1, lnc-ZPBP2-4:1, lnc-GATA3-16:1 and lnc-ACOX3-5:1. KEGG and GO analysis identified that the mitogen-activated protein kinase (MAPK) and PI3K/Akt signaling pathways were the most enriched pathways. After RT-qPCR analysis, lnc-ANGPTL1-3:3 and lnc-GJA10-12:1 exhibited expression patterns that were consistent with those from RNA-seq. Moreover, receiver operating characteristic curve analysis demonstrated that lnc-ANGPTL1-3:3 and lnc-GJA10-12:1 expression levels had high sensitivity and specificity in the diagnosis of SLN metastasis, and that their expression levels were upregulated in patients with axillary lymph node metastasis. Further analysis revealed that lnc-GJA10-12:1 and lnc-ANGPTL1-3:3 were commonly involved in regulating the miR-302 family, including miR-302d-3p and miR-302c-3p, which together targeted AKT1. Additionally, lnc-ANGPTL1-3:3 was predicted to target miR-520b to regulate MAP3K2 expression. lnc-GJA10-12:1 was also predicted to target miR-34a-5p to regulate MAP2K1 and MAP3K9 expression levels, as well as miR-449a to regulate MAP2K1 expression. The results of the present study suggested that lnc-ANGPTL1-3:3 and lnc-GJA10-12:1 may potentially serve a role in SLN metastasis of breast cancer by regulating the PI3K/Akt and MAPK signaling pathways via targeting the miR-302 family, miR-520a-3p, miR-34a-5p and miR-449a. Thus, lnc-ANGPTL1-3:3 and lnc-GJA10-12:1 in SLN may serve as potential markers of breast cancer metastasis.

Molecular subtyping and genomic profiling expand precision medicine in refractory metastatic triple-negative breast cancer: the FUTURE trial

Triple-negative breast cancer (TNBC) is a highly heterogeneous disease, and molecular subtyping may result in improved diagnostic precision and targeted therapies. Our previous study classified TNBCs into four subtypes with putative therapeutic targets. Here, we conducted the FUTURE trial (ClinicalTrials.gov identifier: NCT03805399), a phase Ib/II subtyping-based and genomic biomarker-guided umbrella trial, to evaluate the efficacy of these targets. Patients with refractory metastatic TNBC were enrolled and stratified by TNBC subtypes and genomic biomarkers, and assigned to one of these seven arms: (A) pyrotinib with capecitabine, (B) androgen receptor inhibitor with CDK4/6 inhibitor, (C) anti PD-1 with nab-paclitaxel, (D) PARP inhibitor included, (E) and (F) anti-VEGFR included, or (G) mTOR inhibitor with nab-paclitaxel. The primary end point was the objective response rate (ORR). We enrolled 69 refractory metastatic TNBC patients with a median of three previous lines of therapy (range, 1–8). Objective response was achieved in 20 (29.0%, 95% confidence interval (CI): 18.7%–41.2%) of the 69 intention-to-treat (ITT) patients. Our results showed that immunotherapy (arm C), in particular, achieved the highest ORR (52.6%, 95% CI: 28.9%–75.6%) in the ITT population. Arm E demonstrated favorable ORR (26.1%, 95% CI: 10.2%–48.4% in the ITT population) but with more high grade (≥ 3) adverse events. Somatic mutations of TOP2A and CD8 immunohistochemical score may have the potential to predict immunotherapy response in the immunomodulatory subtype of TNBC. In conclusion, the phase Ib/II FUTURE trial suggested a new concept for TNBC treatment, demonstrating the clinical benefit of subtyping-based targeted therapy for refractory metastatic TNBC.

Candidate methylation sites associated with endocrine therapy resistance in ER+/HER2- breast cancer

BACKGROUND

Estrogen receptor (ER) positive breast cancer is often effectively treated with drugs that inhibit ER signaling, i.e., tamoxifen (TAM) and aromatase inhibitors (AIs). However, 30% of ER+ breast cancer patients develop resistance to therapy leading to tumour recurrence. Changes in the methylation profile have been implicated as one of the mechanisms through which therapy resistance develops. Therefore, we aimed to identify methylation loci associated with endocrine therapy resistance.

METHODS

We used genome-wide DNA methylation profiles of primary ER+/HER2- tumours from The Cancer Genome Atlas in combination with curated data on survival and treatment to predict development of endocrine resistance. Association of individual DNA methylation markers with survival was assessed using Cox proportional hazards models in a cohort of ER+/HER2- tumours (N = 552) and two sub-cohorts corresponding to the endocrine treatment (AI or TAM) that patients received (N = 210 and N = 172, respectively). We also identified multivariable methylation signatures associated with survival using Cox proportional hazards models with elastic net regularization. Individual markers and multivariable signatures were compared with DNA methylation profiles generated in a time course experiment using the T47D ER+ breast cancer cell line treated with tamoxifen or deprived from estrogen.

RESULTS

We identified 134, 5 and 1 CpGs for which DNA methylation is significantly associated with survival in the ER+/HER2-, TAM and AI cohorts respectively. Multi-locus signatures consisted of 203, 36 and 178 CpGs and showed a large overlap with the corresponding single-locus signatures. The methylation signatures were associated with survival independently of tumour stage, age, AI treatment, and luminal status. The single-locus signature for the TAM cohort was conserved among the loci that were differentially methylated in endocrine-resistant T47D cells. Similarly, multi-locus signatures for the ER+/HER2- and AI cohorts were conserved in endocrine-resistant T47D cells. Also at the gene set level, several sets related to endocrine therapy and resistance were enriched in both survival and T47D signatures.

CONCLUSIONS

We identified individual and multivariable DNA methylation markers associated with therapy resistance independently of luminal status. Our results suggest that these markers identified from primary tumours prior to endocrine treatment are associated with development of endocrine resistance.

Assessment of the SRC Inhibition Role in the Efficacy of Breast Cancer Radiotherapy

Introduction: Radiotherapy (RT) is an effective therapeutic method for preventing the recurrence of breast cancer after surgery. The development and improvement of RT are of interest to scientists. Possible improvement of RT via study of dysregulated proteins of breast cancer cell line MDA-MB-231 which is exposed to 10 Gray (Gy) radiation is aim of this study. Methods: Using protein-protein interaction (PPI) network analysis by means of running Cytoscape software via the STRING database, the up-regulated proteins of MDA-MB-231 breast cancer cells irradiated by a single and fractioned 10 Gy 137Cs γ-radiation were analyzed. The network was analyzed by using the Network analyzer to characterize the central genes. The action map was mapped for the queried genes and the added neighbors via CluePedia-STRING ACTIONS-v10.5- 20.11.2017. Results: The 14 differentially expressed proteins (DEPs) plus 10 neighbors interacted to construct a network. Among the 14 queried DEPs, FN1, CSPG4, LRP1, GSN, RTN4, and CTSD were highlighted as a complex set in the analysis. The analysis revealed that SRC as an added neighbor was activated by the critical DEPs. The activation of other oncogenes like AKT1 was also determined. Conclusion: The results indicate that the inhibition of SRC activity or the inhibition of its activators is a useful function of breast cancer RT.

Induction of Apoptosis and Autophagy in Breast Cancer Cells by a Novel HDAC8 Inhibitor

Epigenetic therapy has been demonstrated to be a viable strategy for breast cancer treatment. In this study, we report the anti-tumor activity of a hydroxamate-based histone deacetylase (HDAC)8-selective inhibitor, HMC, in breast cancer cells. MTT assays showed that HMC inhibited cell viability of MCF-7 and MDA-MB-231 cells with IC₅₀ values of 7.7 μM and 9.5 μM, respectively. HMC induced caspase-dependent apoptosis in MCF-7 cells, which was associated with its ability to modulate a series of cell survival-related signaling effectors, including Akt, mTOR, Bax, Mcl-1, and Bcl-2. Additionally, HMC was capable of activating PPARγ, which was accompanied by reduced expression of PPARγ target gene products, such as cyclin D1 and CDK6. HMC increased the production of ROS in MCF-7 cells, which could be partially reversed by the cotreatment with a ROS scavenger (N-acetylcysteine or glutathione). Furthermore, HMC induced autophagy, as characterized by the formation of acidic vesicular organelles and autophagic biomarkers including LC3B-II and Atg5. Notably, pharmacological blockade of autophagy by 3-MA or CQ could attenuate HMC-induced apoptosis, suggesting that autophagy played a self-protective role in HMC-induced cell death. Together, these data suggest the translational potential of HMC to be developed into a potential therapeutic agent for breast cancer therapy.

Distinct functions of AKT isoforms in breast cancer: a comprehensive review

BACKGROUND

AKT, also known as protein kinase B, is a key element of the PI3K/AKT signaling pathway. Moreover, AKT regulates the hallmarks of cancer, e.g. tumor growth, survival and invasiveness of tumor cells. After AKT was discovered in the early 1990s, further studies revealed that there are three different AKT isoforms, namely AKT1, AKT2 and AKT3. Despite their high similarity of 80%, the distinct AKT isoforms exert non-redundant, partly even opposing effects under physiological and pathological conditions. Breast cancer as the most common cancer entity in women, frequently shows alterations of the PI3K/AKT signaling.

MAIN CONTENT

A plethora of studies addressed the impact of AKT isoforms on tumor growth, metastasis and angiogenesis of breast cancer as well as on therapy response and overall survival in patients. Therefore, this review aimed to give a comprehensive overview about the isoform-specific effects of AKT in breast cancer and to summarize known downstream and upstream mechanisms. Taking account of conflicting findings among the studies, the majority of the studies reported a tumor initiating role of AKT1, whereas AKT2 is mainly responsible for tumor progression and metastasis. In detail, AKT1 increases cell proliferation through cell cycle proteins like p21, p27 and cyclin D1 and impairs apoptosis e.g. via p53. On the downside AKT1 decreases migration of breast cancer cells, for instance by regulating TSC2, palladin and EMT-proteins. However, AKT2 promotes migration and invasion most notably through regulation of β-integrins, EMT-proteins and F-actin. Whilst AKT3 is associated with a negative ER-status, findings about the role of AKT3 in regulation of the key properties of breast cancer are sparse. Accordingly, AKT1 is mutated and AKT2 is amplified in some cases of breast cancer and AKT isoforms are associated with overall survival and therapy response in an isoform-specific manner.

CONCLUSIONS

Although there are several discussed hypotheses how isoform specificity is achieved, the mechanisms behind the isoform-specific effects remain mostly unrevealed. As a consequence, further effort is necessary to achieve deeper insights into an isoform-specific AKT signaling in breast cancer and the mechanism behind it.

MicroRNA-429 inhibits cancer cell proliferation and migration by targeting AKT1 in renal cell carcinoma

MicroRNAs (miRNAs or miR) serve as oncogenes and tumor suppressors. In a previous study, it was revealed that has-miRNA-429 (miR-429) is a tumor suppressor in 786-O renal cell carcinoma (RCC) cells. However, its mechanism in RCC remains to be determined. The present study aimed to explain the functional role and mechanism of miR-429 in RCC pathogenesis. Luciferase reporter assays demonstrated that miR-429 overexpression reduced the transcriptional activity of AKT serine/threonine kinase 1 (AKT1). Reverse transcripton-quantitative (RT-q) PCR and western blot analysis indicated that the mRNA and protein expression of AKT1 was downregulated in 786-O RCC cell lines when miR-429 was overexpressed, indicating that miR-429 may directly target AKT1 in RCC. Therefore, miR-429 overexpression enhanced the inhibition of tumor size and weight in nude mice in vivo. The current study indicated that the novel miR-429-regulated pathway may provide insights into RCC oncogenesis and metastasis.

Insights on CXC chemokine receptor 2 in breast cancer: An emerging target for oncotherapy

Breast cancer is the most common malignant neoplasm in women worldwide, and the treatment regimens currently available are far from optimal. Targeted therapy, based on molecular typing of breast cancer, is the most precise form of treatment, and CXC chemokine receptor 2 (CXCR2) is one of the molecular markers used in targeted therapies. As a member of the seven transmembrane G-protein-coupled receptor family, CXCR2 and its associated ligands have been increasingly implicated in tumor-associated processes. These processes include proliferation, angiogenesis, invasion, metastasis, chemoresistance, and stemness and phenotypic maintenance of cancer stem cells. Thus, the inhibition of CXCR2 or its downstream signaling pathways could significantly attenuate tumor progression. Therefore, studies on the biological functions of CXCR2 and its association with neoplasia may help improve the prognosis of breast cancer. Furthermore, the targeting of CXCR2 could supplement the present clinical approaches of breast cancer treatment strategies. The present review discusses the structures and mechanisms of CXCR2 and its ligands. Additionally, the contribution of CXCR2 to the development of breast cancer and its potential therapeutic benefits are also discussed.

A novel tumor suppressor protein encoded by circular AKT3 RNA inhibits glioblastoma tumorigenicity by competing with active phosphoinositide-dependent Kinase-1

Background

The RTK/PI3K/AKT pathway plays key roles in the development and progression of many cancers, including GBM. As a regulatory molecule and a potential drug target, the oncogenic role of AKT has been substantially studied. Three isoforms of AKT have been identified, including AKT1, AKT2 and AKT3, but their individual functions in GBM remain controversial. Moreover, it is not known if there are more AKT alternative splicing variants.

Methods

High-throughput RNA sequencing and quantitative reverse transcription-PCR were used to identify the differentially expressed circRNAs in GBM samples and in paired normal tissues. High throughput RNA sequencing was used to identify circ-AKT3 regulated signaling pathways. Mass spectrometry, western blotting and immunofluorescence staining analyses were used to validate AKT3-174aa expression. The tumor suppressive role of AKT3-174aa was validated in vitro and in vivo. The competing interaction between AKT3-174aa and p-PDK1 was investigated by mass spectrometry and immunoprecipitation analyses.

Results

Circ-AKT3 is a previously uncharacterized AKT transcript variant. Circ-AKT3 is expressed at low levels in GBM tissues compared with the expression in paired adjacent normal brain tissues. Circ-AKT3 encodes a 174 amino acid (aa) novel protein, which we named AKT3-174aa, by utilizing overlapping start-stop codons. AKT3-174aa overexpression decreased the cell proliferation, radiation resistance and in vivo tumorigenicity of GBM cells, while the knockdown of circ-AKT3 enhanced the malignant phenotypes of astrocytoma cells. AKT3-174aa competitively interacts with phosphorylated PDK1, reduces AKT-thr308 phosphorylation, and plays a negative regulatory role in modulating the PI3K/AKT signal intensity.

Conclusions

Our data indicate that the impaired circRNA expression of the AKT3 gene contributes to GBM tumorigenesis, and our data corroborate the hypothesis that restoring AKT3-174aa while inhibiting activated AKT may provide more benefits for certain GBM patients.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1056-5) contains supplementary material, which is available to authorized users.

Identification of Novel Breast Cancer Genes based on Gene Expression Profiles and PPI Data

Background:

Breast cancer is one of the most common malignancies, and a threat to female health all over the world. However, the molecular mechanism of breast cancer has not been fully discovered yet.

Objective:

It is crucial to identify breast cancer-related genes, which could provide new biomarker for breast cancer diagnosis as well as potential treatment targets.

Methods:

Here we used the minimum redundancy-maximum relevance (mRMR) method to select significant genes, then mapped the transcripts of the genes on the Protein-Protein Interaction (PPI) network and traced the shortest path between each pair of two proteins.

Results:

As a result, we identified 24 breast cancer-related genes whose betweenness were over 700. The GO enrichment analysis indicated that the transcription and oxygen level are very important in breast cancer. And the pathway analysis indicated that most of these 24 genes are enriched in prostate cancer, endocrine resistance, and pathways in cancer.

Conclusion:

We hope these 24 genes might be useful for diagnosis, prognosis and treatment for breast cancer.

High-throughput Exploration of the Network Dependent on AKT1 in Mouse Ovarian Granulosa Cells

The PI3K/AKT signaling pathway is known to regulate a broad range of cellular processes, and it is often altered in several types of cancers. Recently, somatic AKT1 mutations leading to a strong activation of this kinase have been reported in juvenile granulosa cell tumors. However, the molecular role of AKT1 in the supporting cell lineage of the ovary is still poorly understood. To get insights into its function in such cells, we depleted Akt1 in murine primary granulosa cells and assessed the molecular consequences at both the transcript and protein levels. We were able to corroborate the involvement of AKT1 in the regulation of metabolism, apoptosis, cell cycle, or cytoskeleton dynamics in this ovarian cell type. Consistently, we showed in established granulosa cells that depletion of Akt1 provoked altered directional persistent migration and increased its velocity. This study also allowed us to put forward new direct and indirect targets of the kinase. Indeed, a series of proteins involved in intracellular transport and mitochondrial physiology were significantly affected by Akt1 depletion. Using in silico analyses, we also propose a set of kinases and transcription factors that can mediate the action of AKT1 on the deregulated transcripts and proteins. Taken altogether, our results provide a resource of direct and indirect AKT1 targets in granulosa cells and may help understand its roles in this ovarian cell type.

The unconventional role of Akt1 in the advanced cancers and in diabetes-promoted carcinogenesis

Decades of research have elucidated the critical role of Akt isoforms in cancer as pro-tumorigenic and metastatic regulators through their specific effects on the cancer cells, tumor endothelial cells and the stromal cells. The pro-cancerous role of Akt isoforms through enhanced cell proliferation and suppression of apoptosis in cancer cells and the cells in the tumor microenvironment is considered a dogma. Intriguingly, studies also indicate that the Akt pathway is essential to protect the endothelial-barrier and prevent aberrant vascular permeability, which is also integral to tumor perfusion and metastasis. To complicate this further, a flurry of recent reports strongly indicates the metastasis suppressive role of Akt, Akt1 in particular in various cancer types. These reports emanated from different laboratories have elegantly demonstrated the paradoxical effect of Akt1 on cancer cell epithelial-to-mesenchymal transition, invasion, tumor endothelial-barrier disruption, and cancer metastasis. Here, we emphasize on the specific role of Akt1 in mediating tumor cell-vasculature reciprocity during the advanced stages of cancers and discuss how Akt1 differentially regulates cancer metastasis through mechanisms distinct from its pro-tumorigenic effects. Since Akt is integral for insulin signaling, endothelial function, and metabolic regulation, we also attempt to shed some light on the specific effects of diabetes in modulating Akt pathway in the promotion of tumor growth and metastasis.

High-throughput Exploration of the Network Dependent on AKT1 in Mouse Ovarian Granulosa Cells

The PI3K/AKT signaling pathway is known to regulate a broad range of cellular processes, and it is often altered in several types of cancers. Recently, somatic AKT1 mutations leading to a strong activation of this kinase have been reported in juvenile granulosa cell tumors. However, the molecular role of AKT1 in the supporting cell lineage of the ovary is still poorly understood. To get insights into its function in such cells, we depleted Akt1 in murine primary granulosa cells and assessed the molecular consequences at both the transcript and protein levels. We were able to corroborate the involvement of AKT1 in the regulation of metabolism, apoptosis, cell cycle, or cytoskeleton dynamics in this ovarian cell type. Consistently, we showed in established granulosa cells that depletion of Akt1 provoked altered directional persistent migration and increased its velocity. This study also allowed us to put forward new direct and indirect targets of the kinase. Indeed, a series of proteins involved in intracellular transport and mitochondrial physiology were significantly affected by Akt1 depletion. Using in silico analyses, we also propose a set of kinases and transcription factors that can mediate the action of AKT1 on the deregulated transcripts and proteins. Taken altogether, our results provide a resource of direct and indirect AKT1 targets in granulosa cells and may help understand its roles in this ovarian cell type.

Akt1 inhibition promotes breast cancer metastasis through EGFR-mediated β-catenin nuclear accumulation

Background

Knockdown of Akt1 promotes Epithelial-to-Mesenchymal Transition in breast cancer cells. However, the mechanisms are not completely understood.

Methods

Western blotting, immunofluorescence, luciferase assay, real time PCR, ELISA and Matrigel invasion assay were used to investigate how Akt1 inhibition promotes breast cancer cell invasion in vitro. Mouse model of lung metastasis was used to measure in vivo efficacy of Akt inhibitor MK2206 and its combination with Gefitinib.

Results

Knockdown of Akt1 stimulated β-catenin nuclear accumulation, resulting in breast cancer cell invasion. β-catenin nuclear accumulation induced by Akt1 inhibition depended on the prolonged activation of EGFR signaling pathway in breast cancer cells. Mechanistic experiments documented that knockdown of Akt1 inactivates PIKfyve via dephosphorylating of PIKfyve at Ser³¹⁸ site, resulting in a decreased degradation of EGFR signaling pathway. Inhibition of Akt1 using MK2206 could induce an increase in the expression of EGFR and β-catenin in breast cancer cells. In addition, MK2206 at a low dosage enhance breast cancer metastasis in a mouse model of lung metastasis, while an inhibitor of EGFR tyrosine kinase Gefitinib could potentially suppress breast cancer metastasis induced by Akt1 inhibition.

Conclusion

EGFR-mediated β-catenin nuclear accumulation is critical for Akt1 inhibition-induced breast cancer metastasis.

Co-Administration of Fish Oil With Signal Transduction Inhibitors Has Anti-Migration Effects in Breast Cancer Cell Lines, in vitro

Background:

There is an urgent need for new therapies to treat cancer metastasis. Fish oil, with high omega 3 fatty acid content, has shown anticancer activity and signal transduction inhibitors have shown anti-metastatic properties.

Objective:

To provide preliminary in vitro data on the anti-migration potential of signal transduction inhibitors and co-administered fish oil.

Methods:

MCF-7, TamR and FasR breast cancer cell lines were used to determine the effects of combinations of PD98059, LY294002 and fish oil in growth assays. Modulations of p-Src and COX-2, both mediators of motility and invasion, were then determined by Western blotting and IHC to ascertain effects on migration potential.

Results:

Migration rates for the three cell lines examined were ranked: FasR>TamR>MCF-7 (p <0.05). Addition of fish oil reduced the number of TamR cells migrating after 48h (p <0.05), while the addition of PD98059 and LY294002 also decreased migratory potential of TamR cells (p <0.05). Addition of PD98059 and LY294002 to TamR cells did not result in a significant decrease in p-Src levels; as was the case when PD98059, LY294002 and 4-hydroxytamoxifen were added to MCF-7 cells. However, the co-administration of fish oil markedly reduced p-Src and COX-2 expression in both cell lines.

Conclusion:

Co-administration of a commercial fish oil with signal transduction inhibitors results in decreased cell migration via an unknown co-operative mechanism and could constitute a novel approach for the treatment of breast cancer metastasis.

AKT isoform-specific expression and activation across cancer lineages

Background

Aberrant AKT activation is prevalent across human cancer lineages, providing an important therapeutic target. AKT comprises three isoforms that mediate critical non-redundant, even opposing functions in cancer pathophysiology. Therefore, targeting specific AKT isoforms in particular cancers may be more effective than pan-AKT inhibition while avoiding disadvantages of pan-AKT inhibition. Currently, AKT isoform-specific expression and activation in cancer are not clearly characterized.

Methods

We systematically characterized AKT isoform-specific expression and activation in 211 cancer cell lines derived from different lineages and genetic backgrounds using a reverse-phase protein array platform.

Results

We found that phosphorylation, but not expression, of AKT1 and AKT2 was coordinated in most but not all cells. Different cancer lineages displayed differential AKT1 and AKT2 expression and phosphorylation. A PIK3CA hotspot mutation H1047R but not E545K was associated with selective activation of AKT2 but not AKT1.

Conclusions

Our study identified and validated AKT isoform-specific expression and phosphorylation in certain cell lines and demonstrated that genetic changes can affect AKT isoform-specific activation. These results provide a more precise understanding of AKT isoform-specific signaling and, in addition, facilitate AKT isoform targeting for personalized cancer therapies.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4654-5) contains supplementary material, which is available to authorized users.

Variation in Akt protein kinases in human populations

The three Akt kinases are related proteins that are essential for normal growth and metabolic regulation and are implicated as key signaling mediators in many physiological and pathophysiological processes. Each Akt is activated by common biochemical signals that act downstream of growth factor and hormone receptors via phosphatidylinositol-3 kinase, and each controls several downstream pathways. The importance of Akt actions in human physiology is strengthened by the rarity of modifying mutations in their genes and by the devastating impact caused by these mutations on growth and development and in disorders such as cancer. Recent advances in genomics present unique opportunities for enhancing our understanding of human physiology and disease predisposition through the lens of population genetics, and the availability of DNA sequence data from 60,706 people in the Exome Aggregation Consortium has prompted this analysis. Results reveal a cohort of potential missense and other alterations in the coding regions of each AKT gene, but with nearly all changes being uncommon. The total number of different alleles per gene varied over an approximately threefold range, from 52 for AKT3 to 158 for AKT2, with variants distributed throughout all Akt protein domains. Previously characterized disease-causing mutations were found rarely in the general population. In contrast, a fairly prevalent amino acid substitution in AKT2 appears to be linked to increased predisposition for type 2 diabetes. Further analysis of variant Akt molecules as identified here will provide opportunities to understand the intricacies of Akt signaling and actions at a population level in human physiology and pathology.

Protein kinase B: emerging mechanisms of isoform-specific regulation of cellular signaling in cancer

The serine/threonine protein kinase B (PKB), also known as Akt, is one of the multifaceted kinases in the human kinome, existing in three isoforms. PKB plays a vital role in phosphoinositide 3-kinase (PI3K)-mediated oncogenesis in various malignancies and is one of the attractive targets for cancer drug discovery. Recent studies have shown that the functional significance of an individual isoform of PKB is not redundant in cancer. It has been found that PKB isoforms play distinct roles in the regulation of cellular invasion and migration during tumorigenesis. PKB activation plays a central role during epithelial-mesenchymal transition, a cellular program required for the cancer cell invasion and migration. However, the differential behavior of each PKB isoform has been shown in the regulation of epithelial-mesenchymal transition. Recent studies have suggested that PKBα (Akt1) plays a conflicting role in tumorigenesis by acting either as a pro-oncogenic factor by suppressing the apoptotic machinery or by restricting tumor invasion. PKBβ (Akt2) promotes cell migration and invasion and similarly PKBγ (Akt3) has been reported to promote tumor migration. As PKB is known for its pro-oncogenic properties, it needs to be unraveled how three isoforms of PKB compensate during tumor progression. In this review, we attempted to sum up how different isoforms of PKB play a role in cancer progression, metastasis, and drug resistance.

CXCR2 promotes breast cancer metastasis and chemoresistance via suppression of AKT1 and activation of COX2

Metastasis and chemoresistance are two major causes of breast cancer death. We show here that the chemokine receptor CXCR2 was overexpressed in breast cancer cell lines and tissues. CXCR2 promoted anti-apoptosis, anti-senescence, and epithelial-to-mesenchymal transition (EMT) of breast cancer cells, leading to the enhanced metastasis and chemoresistance. Further study suggested that AKT1 and cyclooxygenase-2 (COX2; PTGS2) might mediate the CXCR2 signaling to inversely control the breast cancer metastasis and chemoresistance through the regulation of EMT, apoptosis, and senescence. Analyses of clinical data indicate that the high expression of CXCR2 was correlated with the high expression of COX2 and the low expression of AKT1, P85α, E-cadherin, and β-catenin in cancer tissues. Poor outcomes were associated with the high expression of CXCR2 or COX2 while favorable survivals were associated with the high expression of P85α, AKT1, or E-cadherin in all cancer patients. Cox multivariate analysis demonstrated that CXCR2, COX2, and AKT1 could be independent predictors for disease free survivals. All these data suggest that CXCR2 promotes breast cancer metastasis and chemoresistance via suppressing AKT1 and activating COX2. Thus, antagonists of the CXCR2 signaling molecules may be used to treat breast cancer patients particularly with high metastasis and chemoresistance.

Inhibition of AKT1 signaling promotes invasion and metastasis of non-small cell lung cancer cells with K-RAS or EGFR mutations

Accumulating evidence supports a role of the PI3K-AKT pathway in the regulation of cell motility, invasion and metastasis. AKT activation is known to promote metastasis, however under certain circumstances, it also shows an inhibitory activity on metastatic processes, and the cause of such conflicting results is largely unclear. Here we found that AKT1 is an important regulator of metastasis and down-regulation of its activity is associated with increased metastatic potential of A549 cells. Inhibition of AKT1 enhanced migration and invasion in KRAS- or EGFR-mutant non-small cell lung cancer (NSCLC) cells. The allosteric AKT inhibitor MK-2206 promoted metastasis of KRAS-mutated A549 cells in vivo. We next identified that the phosphorylation of Myristoylated alanine-rich C-kinase substrate (MARCKS) and LAMC2 protein level were increased with AKT1 inhibition, and MARCKS or LAMC2 knockdown abrogated migration and invasion induced by AKT1 inhibition. This study unravels an anti-metastatic role of AKT1 in the NSCLC cells with KRAS or EGFR mutations, and establishes an AKT1-MARCKS-LAMC2 feedback loop in this regulation.

Roles of Thyroid Transcription Factor 1 in Lung Cancer Biology

Thyroid transcription factor 1 (TTF-1 or NKX2-1) is a transcription factor of fundamental importance in driving lung maturation and morphogenesis. In the last decade, scientists began to appreciate the functional roles of TTF-1 in lung tumorigenesis. This movement was triggered by the discoveries of genetic alterations of TTF-1 in the form of gene amplification in lung cancer. Many downstream target genes of TTF-1 relevant to the lung cancer biology of TTF-1 have been documented. One of the most surprising findings was that TTF-1 may exhibit either pro- or antitumorigenic activities, an outcome with the complexity exceeding the original anticipation purely based on the fact that TTF-1 undergoes gene amplification in lung cancer. In the coming decade, we believe, we will witness additional surprises as the research exploring the cancer roles of TTF-1 progresses.

Suppression of Akt1-β-catenin pathway in advanced prostate cancer promotes TGFβ1-mediated epithelial to mesenchymal transition and metastasis

Akt1 is essential for the oncogenic transformation and tumor growth in various cancers. However, the precise role of Akt1 in advanced cancers is conflicting. Using a neuroendocrine TRansgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model, we first show that the genetic ablation or pharmacological inhibition of Akt1 in mice blunts oncogenic transformation and prostate cancer (PCa) growth. Intriguingly, triciribine (TCBN)-mediated Akt inhibition in 25-week old, tumor-bearing TRAMP mice and Akt1 gene silencing in aggressive PCa cells enhanced epithelial to mesenchymal transition (EMT) and promoted metastasis to the lungs. Mechanistically, Akt1 suppression leads to increased expression of EMT markers such as Snail1 and N-cadherin and decreased expression of epithelial marker E-cadherin in TRAMP prostate, and in PC3 and DU145 cells. Next, we identified that Akt1 knockdown in PCa cells results in increased production of TGFβ1 and its receptor TGFβ RII, associated with a decreased expression of β-catenin. Furthermore, treatment of PCa cells with ICG001 that blocks nuclear translocation of β-catenin promoted EMT and N-cadherin expression. Together, our study demonstrates a novel role of the Akt1-β-catenin-TGFβ1 pathway in advanced PCa.

Regulation of PI3K effector signalling in cancer by the phosphoinositide phosphatases

Class I phosphoinositide 3-kinase (PI3K) generates phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P₃) at the plasma membrane in response to growth factors, activating a signalling cascade that regulates many cellular functions including cell growth, proliferation, survival, migration and metabolism. The PI3K pathway is commonly dysregulated in human cancer, and drives tumorigenesis by promoting aberrant cell growth and transformation. PtdIns(3,4,5)P₃ facilitates the activation of many pleckstrin homology (PH) domain-containing proteins including the serine/threonine kinase AKT. There are three AKT isoforms that are frequently hyperactivated in cancer through mutation, amplification or dysregulation of upstream regulatory proteins. AKT isoforms have converging and opposing functions in tumorigenesis. PtdIns(3,4,5)P₃ signalling is degraded and terminated by phosphoinositide phosphatases such as phosphatase and tensin homologue (PTEN), proline-rich inositol polyphosphate 5-phosphatase (PIPP) (INPP5J) and inositol polyphosphate 4-phosphatase type II (INPP4B). PtdIns(3,4,5)P₃ is rapidly hydrolysed by PIPP to generate phosphatidylinositol 3,4-bisphosphate (PtdIns(3,4)P₂), which is further hydrolysed by INPP4B to form phosphatidylinositol 3-phosphate (PtdIns3P). PtdIns(3,4)P₂ and PtdIns3P are also important signalling molecules; PtdIns(3,4)P₂ together with PtdIns(3,4,5)P₃ are required for maximal AKT activation and PtdIns3P activates PI3K-dependent serum and glucocorticoid-regulated kinase (SGK3) signalling. Loss of Pten, Pipp or Inpp4b expression or function promotes tumour growth in murine cancer models through enhanced AKT isoform-specific signalling. INPP4B inhibits PtdIns(3,4)P₂-mediated AKT activation in breast and prostate cancer; however, INPP4B expression is increased in acute myeloid leukaemia (AML), melanoma and colon cancer where it paradoxically promotes cell proliferation, transformation and/or drug resistance. This review will discuss how PTEN, PIPP and INPP4B distinctly regulate PtdIns(3,4,5)P₃ signalling downstream of PI3K and how dysregulation of these phosphatases affects cancer outcomes.

p70S6K1 (S6K1)-mediated Phosphorylation Regulates Phosphatidylinositol 4-Phosphate 5-Kinase Type I γ Degradation and Cell Invasion

Phosphatidylinositol 4-phosphate 5-kinase type I γ (PIPKIγ90) ubiquitination and subsequent degradation regulate focal adhesion assembly, cell migration, and invasion. However, it is unknown how upstream signals control PIPKIγ90 ubiquitination or degradation. Here we show that p70S6K1 (S6K1), a downstream target of mechanistic target of rapamycin (mTOR), phosphorylates PIPKIγ90 at Thr-553 and Ser-555 and that S6K1-mediated PIPKIγ90 phosphorylation is essential for cell migration and invasion. Moreover, PIPKIγ90 phosphorylation is required for the development of focal adhesions and invadopodia, key machineries for cell migration and invasion. Surprisingly, substitution of Thr-553 and Ser-555 with Ala promoted PIPKIγ90 ubiquitination but enhanced the stability of PIPKIγ90, and depletion of S6K1 also enhanced the stability of PIPKIγ90, indicating that PIPKIγ90 ubiquitination alone is insufficient for its degradation. These data suggest that S6K1-mediated PIPKIγ90 phosphorylation regulates cell migration and invasion by controlling PIPKIγ90 degradation.

Revealing the role of VEGFA in clear cell sarcoma of the kidney by protein-protein interaction network and significant pathway analysis

Despite clear cell sarcoma of the kidney (CCSK) being the second most common renal tumor in children, its mechanism has not yet been fully investigated. The aim of the present study was to investigate the potential role of vascular endothelial growth factor A (VEGFA) in CCSK development. Following preprocessing of the original GSE2712 data, the differentially-expressed genes (DEGs) between 14 CCSK and 3 fetal kidney samples were identified through Significance Analysis of Microarrays, using the R package. Pathway enrichment analysis was then performed on the DEGs. A protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins database and the DEGs that were enriched in the most significant pathways. Following this, gene ontology analysis was performed on the VEGFA-associated genes, whilst transcription factor binding site analysis was conducted on the hot genes. A total of 2,681 DEGs, including 543 upregulated and 2,138 downregulated genes, were identified, and these were significantly enriched in pathways associated with cancer and focal adhesion. Furthermore, VEGFA, integrin β1, integrin αV, v-akt murine thymoma viral oncogene homolog 1 and endothelial growth factor receptor were identified as hot genes in the PPI network. In addition, the upregulated VEGFA-associated genes, cyclin D1 and cyclin-dependent kinase inhibitor 1B, affected kinase regulation, and the downregulated VEGFA-associated genes, receptor tyrosine-protein kinase erbB-2, mesenchymal-epithelial transition tyrosine kinase receptor and kinase insert domain receptor, were enriched in the protein tyrosine kinase process. It was identified that VEGFA was regulated by restorer of fertility, erythromycin resistance methylase, GA binding protein subunit α, norepinephrine transporter, nuclear factor κB and Sp2 transcription factor genes. Overall, VEGFA and its associated genes serve important roles during CCSK development, and alongside transcription factors, they may function as novel therapeutic targets for disease treatment.