Akt as a therapeutic target in cancer

Microarray-based detection and expression analysis of drug resistance in an animal model of peritoneal metastasis from colon cancer

Chemotherapy drugs efficiently eradicate rapidly dividing differentiated cells by inducing cell death, but poorly target slowly dividing cells, including cancer stem cells and dormant cancer cells, in the later course of treatment. Prolonged exposure to chemotherapy results in a decrease in the proportion of apoptotic cells in the tumour mass. To investigate and characterize the molecular basis of this phenomenon, microarray-based expression analysis was performed to compare tHcred2-DEVD-EGFP-caspase 3-sensor transfected C-26 tumour cells that were harvested after engraftment into mice treated with or without 5-FU. Peritoneal metastasis was induced by intraperitoneal injection of C-26 cells, which were subsequently reisolated from omental metastatic tumours after the mice were sacrificed by the end of the 10th day after tumour injection. The purity of reisolated tHcred2-DEVD-EGFP-caspase 3-sensor-expressing C-26 cells was confirmed using FLIM, and total RNA was extracted for gene expression profiling. The validation of relative transcript levels was carried out via real-time semiquantitative RT‒PCR assays. Our results demonstrated that chemotherapy induced the differential expression of mediators of cancer cell dormancy and cell survival-related genes and downregulation of both intrinsic and extrinsic apoptotic signalling pathways. Despite the fact that some differentially expressed genes, such as BMP7 and Prss11, have not been thoroughly studied in the context of chemoresistance thus far, they might be potential candidates for future studies on overcoming drug resistance.

Discovery of a Pimaradiene that Decreases Viability of MDA-MB-468 Cells Through Inhibition of EGFR Signaling Pathway

Triple-negative breast cancer (TNBC) is characterized by strong invasiveness, high relapse rates, and poor overall survival. It occurs in approximately 15-20 % of all breast cancer cases. Natural compounds are a promising option for managing breast cancer. ent-8(14),15-Pimaradiene-2β,19-diol (JXE-23), is a pimaradiene isolated from the fern Aleuritopteris albofusca. However, the effects and molecular mechanisms of JXE-23 on cancer cells are still unknown. Thus, this study was designed to determine the potential of JXE-23 for its anticancer properties in TNBC cells. JXE-23 was evaluated for its antiproliferative activity in vitro against human breast cancer cell lines, and showed selectively cytotoxic activity against MDA-MB-468, an EGFR-overexpressing TNBC cancer cell line, with an IC50 value of 1.17±0.04 μM. Moreover, mechanistic investigations indicated that JXE-23 was significantly capable of inhibiting cell proliferation and viability in MDA-MB-468 cells. In addition, JXE-23 exerted an anticancer effect against MDA-MB-468 cells via restraining cell migration in a dose-dependent mode. Moreover, after treatment with JXE-23, the protein expressions of pEGFR, pERK, pAkt and p-p70S6K were significantly reduced in MDA-MB-468 cells. The results underscored that JXE-23 could be a potential lead compound for the treatment of EGFR-overexpressing TNBC cells.

Unraveling the relationship between the renin-angiotensin system and endometrial cancer: a comprehensive review

Endometrial cancer (EC), the most common adenocarcinoma, represents 90% of uterine cancer in women with an increased incidence of occurrence attributed to age, obesity, hypertension, and hypoestrogenism. Being the most common gynecological malignancy in women, it shows a relation with the activation of different components of the renin-angiotensin system (RAS), which is predominantly involved in maintaining blood pressure, salt, water, and aldosterone secretion, thereby playing a significant role in the etiology of hypertension. The components of the RAS, i.e., ACE-I, ACE-II, AT1R, AT2R, and Pro(renin) receptor, are widely expressed in both glandular and stromal cells of the endometrium, with varying levels throughout the different phases of the menstrual cycle. This causes the endometrial RAS to implicate angiogenesis, neovascularization, and cell proliferation. Thus, dysfunctioning of the endometrial RAS could predispose the growth and spread of EC. Interestingly, the increased expression of AngII, AGTR1, and AGTR2 showed advancement in the stages and progression of EC via the prorenin/ATP6AP2 and AngII/AGTR1 pathway. Therefore, this review corresponds to unraveling the relationship between the progression and development of endometrial cancer with the dysfunction in the expression of various components associated with RAS in maintaining blood pressure.

Notch signaling in female cancers: a multifaceted node to overcome drug resistance

Drug resistance is one of the main challenges in cancer therapy, including in the treatment of female-specific malignancies, which account for more than 60% of cancer cases among women. Therefore, elucidating the underlying molecular mechanisms is an urgent need in gynecological cancers to foster novel therapeutic approaches. Notably, Notch signaling, including either receptors or ligands, has emerged as a promising candidate given its multifaceted role in almost all of the hallmarks of cancer. Concerning the connection between Notch pathway and drug resistance in the afore-mentioned tumor contexts, several studies focused on the Notch-dependent regulation of the cancer stem cell (CSC) subpopulation or the induction of the epithelial-to-mesenchymal transition (EMT), both features implicated in either intrinsic or acquired resistance. Indeed, the present review provides an up-to-date overview of the published results on Notch signaling and EMT- or CSC-driven drug resistance. Moreover, other drug resistance-related mechanisms are examined such as the involvement of the Notch pathway in drug efflux and tumor microenvironment. Collectively, there is a long way to go before every facet will be fully understood; nevertheless, some small pieces are falling neatly into place. Overall, the main aim of this review is to provide strong evidence in support of Notch signaling inhibition as an effective strategy to evade or reverse resistance in female-specific cancers.

Molecular Analysis of Adenocarcinomas of the Rete Testis Demonstrates Frequent Alterations in Genes Involved in Cell Cycle Regulation

Adenocarcinomas of the rete testis (ACRT) are rare and aggressive testicular neoplasms that present predominantly in older men and have a tendency for early systemic spread. Their morphology spans a wide spectrum, including tumors with glandular, solid, papillary, micropapillary, glomeruloid, cribriform and sarcomatoid growth patterns, or a combination thereof. The genomic alterations associated with these tumors have not been studied previously. We assessed eight ACRT published in prior clinicopathologic series using a solid tumor DNA sequencing panel. Pathogenic variants were identified in 6/8 cases. More specifically, 4 cases demonstrated inactivation of genes involved in cell cycle regulation, including CDKN2A, BAP1, TP53 and RB1. CDKN2A was the only recurrently affected gene, with pathogenic variants detected in 3/8 cases. One of these 3 cases had molecular evidence of concurrent homozygous (i.e., biallelic) NF2 inactivation by a frameshift variant and loss of the wild-type copy of the gene. One case had an internal tandem duplication of AKT which has been previously described in juvenile granulosa cell tumor and sclerosing pneumocytoma and results in downstream activation of PI3K signaling. The remaining case with positive molecular findings harbored two concurrent truncating SETD2 variants. Multiple arm-level and chromosome-level copy number events were present in 3/8 cases, all of which harbored variants in genes involved in cell cycle regulation. In summary, ACRT are rare tumors with frequent inactivation of genes that play a major role cell cycle regulation, and a subset harbors variants which are potentially amenable to targeted therapy.

A phase I pharmacokinetic study of copanlisib in Chinese patients with relapsed indolent non-Hodgkin lymphoma

PURPOSE

Copanlisib, a pan-PI3K inhibitor, has previously shown clinical efficacy and a tolerable safety profile in patients with indolent non-Hodgkin lymphoma. However, the pharmacokinetics, safety, tolerability, and efficacy of copanlisib in Chinese patients have not been reported.

METHODS

This was a single-arm, open-label, phase I study of copanlisib in Chinese patients with relapsed or refractory indolent non-Hodgkin lymphoma (iNHL). Patients received a single intravenous 60 mg infusion of copanlisib over 1 h on days 1, 8, and 15 of a 28-day cycle, with 1 week of rest. Safety was monitored throughout the study, and plasma copanlisib levels were measured for pharmacokinetic analysis. Tumor response was determined by independent central radiologic review.

RESULTS

Sixteen patients were enrolled and 13 were treated with 60 mg of copanlisib for a median of 15.0 weeks. With a C_max of 566 μg/L and a AUC (0-24) of 1880 μg·h/L following single intravenous infusion, the pharmacokinetic parameters of copanlisib were consistent with that in previous studies, and no accumulation in plasma was observed. Treatment-emergent adverse events were reported for all 13 patients, the most common of which were hyperglycemia (100.0%), hypertension (76.9%), decreased neutrophil count (76.9%), and decreased white blood cell count (69.2%). Seven out of 12 evaluated patients achieved partial response, resulting in an overall response rate of 58.3% CONCLUSIONS: Copanlisib was well tolerated in Chinese patients with relapsed or refractory iNHL at the dose of 60 mg and demonstrated encouraging disease control, thus warranting further clinical investigation.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03498430 (April 13, 2018).

Targeting PI3K/Akt signal transduction for cancer therapy

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway plays a crucial role in various cellular processes and is aberrantly activated in cancers, contributing to the occurrence and progression of tumors. Examining the upstream and downstream nodes of this pathway could allow full elucidation of its function. Based on accumulating evidence, strategies targeting major components of the pathway might provide new insights for cancer drug discovery. Researchers have explored the use of some inhibitors targeting this pathway to block survival pathways. However, because oncogenic PI3K pathway activation occurs through various mechanisms, the clinical efficacies of these inhibitors are limited. Moreover, pathway activation is accompanied by the development of therapeutic resistance. Therefore, strategies involving pathway inhibitors and other cancer treatments in combination might solve the therapeutic dilemma. In this review, we discuss the roles of the PI3K/Akt pathway in various cancer phenotypes, review the current statuses of different PI3K/Akt inhibitors, and introduce combination therapies consisting of signaling inhibitors and conventional cancer therapies. The information presented herein suggests that cascading inhibitors of the PI3K/Akt signaling pathway, either alone or in combination with other therapies, are the most effective treatment strategy for cancer.

Mineral trioxide aggregate-induced AMPK activation stimulates odontoblastic differentiation of human dental pulp cells

AIM

To investigate the role of autophagy in MTA-induced odontoblastic differentiation of human dental pulp cells (HDPCs).

METHODOLOGY

In MTA-treated HDPCs, odontoblastic differentiation was assessed based on expression levels of dentine sialophosphoprotein (DSPP) and dentine matrix protein 1 (DMP1), alkaline phosphatase activity (ALP) activity by ALP staining and the formation of mineralized nodule by Alizarin red S staining. Expression of microtubule-associated protein 1A/1B-light chain3 (LC3), adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signalling molecules and autophagy-related genes was analysed by Western blot analysis and Acridine orange staining was used to detect autophagic lysosome. For in vivo experiments, tooth cavity preparation models on rat molars were established and the expression of proteins-related odontogenesis and autophagy markers was observed by Immunohistochemistry and Western blot analysis. Kruskal-Wallis with Dunn's multiple comparison was used for statistical analysis.

RESULTS

Mineral trioxide aggregate (MTA) promoted odontoblastic differentiation of HDPCs, accompanied by autophagy induction, including formation of autophagic lysosome and cleavage of LC3 to LC3II (P < 0.05). Conversely, inhibition of autophagy through 3MA significantly attenuated the expression level of DSPP (P < 0.05) and DMP1 (P < 0.05) as well as formation of mineralized nodules (P < 0.05), indicating the functional significance of autophagy in MTA-induced odontoblastic differentiation. Also, MTA increased the activity of AMPK (P < 0.01), whereas inhibition of AMPK by compound C downregulated DSPP (P < 0.01) and DMP1 (P < 0.05), but increased the phosphorylation of mTOR (P < 0.05), p70S6 (P < 0.01) and Unc-51-like kinases 1 (ULK1) (ser757) (P < 0.01), explaining the involvement of AMPK pathway in MTA-induced odontoblast differentiation. In vivo study, MTA treatment after tooth cavity preparation on rat molars upregulated DMP-1 and DSPP as well as autophagy-related proteins LC3II and p62, and enhanced the phosphorylation of AMPK.

CONCLUSION

MTA induced odontoblastic differentiation and mineralization by modulating autophagy with AMPK activation in HDPCs. Autophagy regulation is a new insight on regenerative endodontic therapy using MTA treatment.

Crosstalk of Hedgehog and mTORC1 Pathways

Hedgehog (Hh) signaling and mTOR signaling, essential for embryonic development and cellular metabolism, are both coordinated by the primary cilium. Observations from cancer cells strongly indicate crosstalk between Hh and mTOR signaling. This hypothesis is supported by several studies: Evidence points to a TGFβ-mediated crosstalk; Increased PI3K/AKT/mTOR activity leads to increased Hh signaling through regulation of the GLI transcription factors; increased Hh signaling regulates mTORC1 activity positively by upregulating NKX2.2, leading to downregulation of negative mTOR regulators; GSK3 and AMPK are, as members of both signaling pathways, potentially important links between Hh and mTORC1 signaling; The kinase DYRK2 regulates Hh positively and mTORC1 signaling negatively. In contrast, both positive and negative regulation of Hh has been observed for DYRK1A and DYRK1B, which both regulate mTORC1 signaling positively. Based on crosstalk observed between cilia, Hh, and mTORC1, we suggest that the interaction between Hh and mTORC1 is more widespread than it appears from our current knowledge. Although many studies focusing on crosstalk have been carried out, contradictory observations appear and the interplay involving multiple partners is far from solved.

Mechanism of Anti-Cancer Activity of Curcumin on Androgen-Dependent and Androgen-Independent Prostate Cancer

Prostate cancer (PCa) is a heterogeneous disease and ranked as the second leading cause of cancer-related deaths in males worldwide. The global burden of PCa keeps rising regardless of the emerging cutting-edge technologies for treatment and drug designation. There are a number of treatment options which are effectively treating localised and androgen-dependent PCa (ADPC) through hormonal and surgery treatments. However, over time, these cancerous cells progress to androgen-independent PCa (AIPC) which continuously grow despite hormone depletion. At this particular stage, androgen depletion therapy (ADT) is no longer effective as these cancerous cells are rendered hormone-insensitive and capable of growing in the absence of androgen. AIPC is a lethal type of disease which leads to poor prognosis and is a major contributor to PCa death rates. A natural product-derived compound, curcumin has been identified as a pleiotropic compound which capable of influencing and modulating a diverse range of molecular targets and signalling pathways in order to exhibit its medicinal properties. Due to such multi-targeted behaviour, its benefits are paramount in combating a wide range of diseases including inflammation and cancer disease. Curcumin exhibits anti-cancer properties by suppressing cancer cells growth and survival, inflammation, invasion, cell proliferation as well as possesses the ability to induce apoptosis in malignant cells. In this review, we investigate the mechanism of curcumin by modulating multiple signalling pathways such as androgen receptor (AR) signalling, activating protein-1 (AP-1), phosphatidylinositol 3-kinases/the serine/threonine kinase (PI3K/Akt/mTOR), wingless (Wnt)/ß-catenin signalling, and molecular targets including nuclear factor kappa-B (NF-κB), B-cell lymphoma 2 (Bcl-2) and cyclin D1 which are implicated in the development and progression of both types of PCa, ADPC and AIPC. In addition, the role of microRNAs and clinical trials on the anti-cancer effects of curcumin in PCa patients were also reviewed.

A Novel Method to Efficiently Highlight Nonlinearly Expressed Genes

For precision medicine, there is a need to identify genes that accurately distinguish the physiological state or response to a particular therapy, but this can be challenging. Many methods of analyzing differential expression have been established and applied to this problem, such as t-test, edgeR, and DEseq2. A common feature of these methods is their focus on a linear relationship (differential expression) between gene expression and phenotype. However, they may overlook nonlinear relationships due to various factors, such as the degree of disease progression, sex, age, ethnicity, and environmental factors. Maximal information coefficient (MIC) was proposed to capture a wide range of associations of two variables in both linear and nonlinear relationships. However, with MIC it is difficult to highlight genes with nonlinear expression patterns as the genes giving the most strongly supported hits are linearly expressed, especially for noisy data. It is thus important to also efficiently identify nonlinearly expressed genes in order to unravel the molecular basis of disease and to reveal new therapeutic targets. We propose a novel nonlinearity measure called normalized differential correlation (NDC) to efficiently highlight nonlinearly expressed genes in transcriptome datasets. Validation using six real-world cancer datasets revealed that the NDC method could highlight nonlinearly expressed genes that could not be highlighted by t-test, MIC, edgeR, and DEseq2, although MIC could capture nonlinear correlations. The classification accuracy indicated that analysis of these genes could adequately distinguish cancer and paracarcinoma tissue samples. Furthermore, the results of biological interpretation of the identified genes suggested that some of them were involved in key functional pathways associated with cancer progression and metastasis. All of this evidence suggests that these nonlinearly expressed genes may play a central role in regulating cancer progression.

Therapeutic Inducers of Apoptosis in Ovarian Cancer

Ovarian cancers remain one of the most common causes of gynecologic cancer-related death in women worldwide. The standard treatment comprises platinum-based chemotherapy, and most tumors develop resistance to therapeutic drugs. One mechanism of developing drug resistance is alterations of molecules involved in apoptosis, ultimately assisting in the cells’ capability to evade death. Thus, there is a need to focus on identifying potential drugs that restore apoptosis in cancer cells. Here, we discuss the major inducers of apoptosis mediated through various mechanisms and their usefulness as potential future treatment options for ovarian cancer. Broadly, they can target the apoptotic pathways directly or affect apoptosis indirectly through major cancer-pathways in cells. The direct apoptotic targets include the Bcl-2 family of proteins and the inhibitor of apoptotic proteins (IAPs). However, indirect targets include processes related to homologous recombination DNA repair, micro-RNA, and p53 mutation. Besides, apoptosis inducers may also disturb major pathways converging into apoptotic signals including janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3), wingless-related integration site (Wnt)/β-Catenin, mesenchymal-epithelial transition factor (MET)/hepatocyte growth factor (HGF), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), and phosphatidylinositol 3-kinase (PI3K)/v-AKT murine thymoma viral oncogene homologue (AKT)/mammalian target of rapamycin (mTOR) pathways. Several drugs in our review are undergoing clinical trials, for example, birinapant, DEBIO-1143, Alisertib, and other small molecules are in preclinical investigations showing promising results in combination with chemotherapy. Molecules that exhibit better efficacy in the treatment of chemo-resistant cancer cells are of interest but require more extensive preclinical and clinical evaluation.

Targeting AKT for cancer therapy

Introduction: Targeted therapies in cancer aim to inhibit specific molecular targets responsible for enhanced tumor growth. AKT/PKB (protein kinase B) is a serine threonine kinase involved in several critical cellular pathways, including survival, proliferation, invasion, apoptosis, and angiogenesis. Although phosphatidylinositol-3 kinase (PI3K) is the key regulator of AKT activation, numerous stimuli and kinases initiate pro-proliferative AKT signaling which results in the activation of AKT pathway to drive cellular growth and survival. Activating mutations and amplification of components of the AKT pathway are implicated in the pathogenesis of many cancers including breast and ovarian. Given its importance, AKT, it has been validated as a promising therapeutic target.Areas covered: This article summarizes AKT's biological function and different classes of AKT inhibitors as anticancer agents. We also explore the efficacy of AKT inhibitors as monotherapies and in combination with cytotoxic and other targeted therapies.Expert opinion: The complex mechanism following AKT inhibition requires the addition of other therapies to prevent resistance and improve clinical response. Further studies are necessary to determine additional rational combinations that can enhance efficacy of AKT inhibitors, potentially by targeting compensatory mechanisms, and/or enhancing apoptosis. The identification of biomarkers of response is essential for the development of successful therapeutics.

Akt in cancer: Mediator and more

Akt is a serine/threonine kinase and it participates in the key role of the PI3K signaling pathway. The Akt can be activated by a wide range of growth signals and the biochemical mechanisms leading to Akt activation are well defined. Once activated, Akt modulates the function of many downstream proteins involved in cellular survival, proliferation, migration, metabolism, and angiogenesis. The Akt is a central node of many signaling pathways and it is frequently deregulated in many types of human cancers. In this review, we provide an overview of Akt function and its role in the hallmarks of human cancer. We also discussed various mechanisms of Akt dysregulation in cancers, including epigenetic modifications like methylation, post-transcriptional non-coding RNAs-mediated regulation, and the overexpression and mutation.

Phosphorylated-Akt overexpression is associated with a higher risk of brain metastasis in patients with non-small cell lung cancer

Brain metastasis (BM) of non-small cell lung cancer (NSCLC) is relatively common and has a poor prognosis. Moreover, identifying which patients are more likely to develop BM is challenging. Akt, a serine/threonine-specific protein kinase, can be activated in various tumors, including lung cancer, and may be associated with poor prognosis. Here, we used immunohistochemistry to evaluate phosphorylated-Akt (p-Akt) expression in tumor tissues of 99 NSCLC patients. We also analyzed the genotype of the patients for two single nucleotide polymorphisms (SNPs) of the AKT1 gene, rs2498804 and rs2494732. We found that p-Akt expression differs between NSCLC patients and correlates with the risk of BM. Indeed, patients exhibiting medium to high p-Akt expression had a higher incidence of BM than those exhibiting low to no p-Akt expression (39% vs 16%). Our data also show that patients with the rs2498804 GT/GG and rs2494732 CT/TT variant genotypes were more likely to exhibit higher levels of p-Akt expression than those with the rs2498804 TT and rs2494732 CC variant genotypes (35% vs. 24% and 37% vs. 25%, respectively). Our results suggest that the level of expression of p-Akt, which may be affected by the AKT1 genotype, is correlated with the risk of BM. However, further studies are needed to establish p-Akt as a predictive marker for BM in NSCLC patients.

Targeting phosphoinositide-3-kinase pathway in biliary tract cancers: A remedial route?

Biliary tract cancers (BTC) are aggressive tumours with a low survival rate. At the advent of the genomic era, various genetic mutations in cell signalling pathways have been incriminated in carcinogenesis. Genomic analysis studies have connected main components of the phosphoinositide-3-kinase (PI3K) signalling pathway to BTC. PI3K pathway playing a central role in cell signalling and being deregulated in various tumours has been studied as a target for chemotherapy. Novel compounds have also been identified in preclinical trials that specifically target the PI3K pathway in BTCs, but these studies have not accelerated to clinical use. These novel compounds can be examined in upcoming studies to validate them as potential therapeutic agents, as further research is required to combat the growing need for adjuvant chemotherapy to successfully battle this tumour type. Furthermore, these molecules could also be used along with gemcitabine, cisplatin and 5-fluorouracil to improve sensitivity of the tumour tissue to chemotherapy. This review focuses on the basics of PI3K signalling, genetic alterations of this pathway in BTCs and current advancement in targeting this pathway in BTCs. It emphasizes the need for gene-based drug screening in BTC. It may reveal various novel targets and drugs for amelioration of survival in patients with BTC and serve as a stepping stone for further research.

Targeting Cancer Stem Cells for Chemoprevention of Pancreatic Cancer

Pancreatic ductal adenocarcinoma is one of the deadliest cancers worldwide and the fourth leading cause of cancer-related deaths in United States. Regardless of the advances in molecular pathogenesis and consequential efforts to suppress the disease, this cancer remains a major health problem in United States. By 2030, the projection is that pancreatic cancer will be climb up to be the second leading cause of cancer-related deaths in the United States. Pancreatic cancer is a rapidly invasive and highly metastatic cancer, and does not respond to standard therapies. Emerging evidence supports that the presence of a unique population of cells called cancer stem cells (CSCs) as potential cancer inducing cells and efforts are underway to develop therapeutic strategies targeting these cells. CSCs are rare quiescent cells, and with the capacity to self-renew through asymmetric/symmetric cell division, as well as differentiate into various lineages of cells in the cancer. Studies have been shown that CSCs are highly resistant to standard therapy and also responsible for drug resistance, cancer recurrence and metastasis. To overcome this problem, we need novel preventive agents that target these CSCs. Natural compounds or phytochemicals have ability to target these CSCs and their signaling pathways. Therefore, in the present review article, we summarize our current understanding of pancreatic CSCs and their signaling pathways, and the phytochemicals that target these cells including curcumin, resveratrol, tea polyphenol EGCG (epigallocatechin- 3-gallate), crocetinic acid, sulforaphane, genistein, indole-3-carbinol, vitamin E δ- tocotrienol, Plumbagin, quercetin, triptolide, Licofelene and Quinomycin. These natural compounds or phytochemicals, which inhibit cancer stem cells may prove to be promising agents for the prevention and treatment of pancreatic cancers.

Anti-cancer effects of Kaempferia parviflora on ovarian cancer SKOV3 cells

BACKGROUND

Kaempferia parviflora (KP) is an herb found in the north of Thailand and used as a folk medicine for improving vitality. Current reports have shown the anti-cancer activities of KP. However, the anti-cancer effects of KP on highly aggressive ovarian cancer have not been investigated. Therefore, we determined the effects of KP on cell proliferation, migration, and cell death in SKOV3 cells.

METHODS

Ovarian cancer cell line, SKOV3 was used to investigate the anti-cancer effect of KP extract. Cell viability, cell proliferation, MMP activity, cell migration, and invasion were measured by MTT assay, cell counting, gelatin zymography, wound healing assay, and Transwell migration and invasion assays, respectively. Cell death was determined by trypan blue exclusion test, AnnexinV/PI with flow cytometry, and nuclear staining. The level of ERK and AKT phosphorylation, and caspase-3, caspase-7, caspase-9 was investigated by western blot analysis.

RESULTS

KP extract was cytotoxic to SKOV3 cells when the concentration was increased, and this effect could still be observed even though EGF was present. Besides, the cell doubling time was significantly prolonged in the cells treated with KP. Moreover, KP strongly suppressed cell proliferation, cell migration and invasion. These consequences may be associated with the ability of KP in inhibiting the activity of MMP-2 and MMP-9 assayed by gelatin zymography. Moreover, KP at high concentrations could induce SKOV3 cell apoptosis demonstrated by AnnexinV/PI staining and flow cytometry. Consistently, nuclear labelling of cells treated with KP extract showed DNA fragmentation and deformity. The induction of caspase-3, caspase-7, and caspase-9 indicates that KP induces cell death through the intrinsic apoptotic pathway. The antitumor activities of KP might be regulated through PI3K/AKT and MAPK pathways since the phosphorylation of AKT and ERK1/2 was reduced.

CONCLUSIONS

The inhibitory effects of KP in cell proliferation, cell migration and invasion together with apoptotic cell death induction in SKOV3 cells suggest that KP has a potential to be a new candidate for ovarian cancer chemotherapeutic agent.

Antiproliferative effects of the CDK6 inhibitor PD0332991 and its effect on signaling networks in gastric cancer cells

PD0332991 (palbociclib/Ibrance^®) is a cyclin-dependent kinase (CDK)4/6 inhibitor that has recently been approved for the treatment of estrogen receptor-positive advanced breast cancer. The present study investigated the antiproliferative effects of PD0332991 on gastric cancer (GC) cells and the underlying molecular mechanisms. The activity of PD0332991 was tested in several GC cell lines, including AGS, KATO-III, NCI-N87 and HS746T. Growth inhibitory activity of PD0332991, alone or in combination with fluorouracil (5-FU), was measured by MTT assay. The effects of PD0332991 on cell cycle progression were analyzed by flow cytometry and western blotting. Protein pathway array and Ingenuity Pathway Analysis were used to identify signaling pathways that may mediate the antiproliferative effects of PD0332991. PD0332991 inhibited proliferation in a dose-dependent manner and enhanced the activity of 5-FU in all GC cell lines tested. Cells treated with PD0332991 exhibited cell cycle arrest in G₁ phase of the cell cycle, whereas the number of cells in G₂/M phase was decreased. PD0332991 also inhibited CDK6-specific phosphorylation of retinoblastoma on Ser780, reduced the expression of cyclin D1, and induced expression of p53 and p27. Furthermore, 31 proteins were identified, the expression of which was significantly altered following treatment with PD0332991 in at least three cell lines. Pathway analysis indicated that the altered proteins were frequently associated with cell death, cell cycle and the molecular mechanism of cancer. The results of the present study indicated that PD0332991 may inhibit cell proliferation via modulation of the cell cycle, and may affect numerous oncogenic signaling pathways. Therefore, PD0332991 may be considered effective for the treatment of GC.

Induction of apoptosis by Dae-Hwang-Mok-Dan-Tang in HCT-116 colon cancer cells through activation of caspases and inactivation of the phosphatidylinositol 3-kinase/Akt signaling

BACKGROUND

Dae-Hwang-Mok-Dan-Tang (DHMDT), a traditional Korean medicine, contains five species of medicinal plants and has been used to treat patients with digestive tract cancer for hundreds of years; however, its anticancer mechanism is poorly understood. In the present study, we investigated the proapoptotic effects of DHMDT in human colon cancer HCT-116 cells.

METHODS

Cytotoxicity was evaluated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Apoptosis was detected using 4,6-diamidino-2-phenyllindile staining, agarose gel electrophoresis, and flow cytometry. The protein levels were determined using Western blot analysis. Caspase activity was measured using a colorimetric assay.

RESULTS

Treatment with DHMDT resulted in a growth inhibition coupled with apoptosis induction, which was associated with the downregulation of members of IAP (inhibitor of apoptosis protein) family, including XIAP and survivin, and the activation of caspase-9 and -3 accompanied by proteolytic degradation of poly(ADP-ribose)-polymerase and phospholipase C-γ1. DHMDT treatment also showed a correlation with the translocation of proapoptotic Bax to mitochondria, the loss of mitochondrial membrane permeabilization, and the cytochrome c release from the mitochondria to the cytosol. Moreover, DHMDT increased the levels of death receptor-associated ligands and enhanced activation of caspase-8 and cleavage of its substrate, Bid. However, the pan-caspase inhibitor could reverse DHMDT-induced apoptosis. In addition, DHMDT suppressed the phosphoinositide 3-kinase (PI3K)/Akt pathway, and treatment with a potent inhibitor of PI3K further increased the apoptotic activity of DHMDT.

CONCLUSION

Our data showed that DHMDT induces HCT-116 cell apoptosis by activating intrinsic and extrinsic apoptosis pathways and by suppressing the PI3K/Akt signal pathway; however, further studies are needed to identify the active compounds.

Kaempferol Inhibits the Invasion and Migration of Renal Cancer Cells through the Downregulation of AKT and FAK Pathways

Kaempferol, which is isolated from several natural plants, is a polyphenol belonging to the subgroup of flavonoids. Kaempferol exhibits various pharmacological activities, including anti-inflammatory, antioxidant, antimicrobial, and anticancer activities. In this study, kaempferol can significantly inhibit the invasion and migration of 786-O renal cell carcinoma (RCC) without cytotoxicity. We examined the potential mechanisms underlying its anti-invasive activities on 786-O RCC cells. Western blot was performed, and the results showed that kaempferol attenuates the manifestation of metalloproteinase-2 (MMP-2) protein and activity. The inhibitive effect of kaempferol on MMP-2 may be attributed to the downregulation of phosphorylation of Akt and focal adhesion kinase (FAK). By examining the SCID mice model, we found that kaempferol can safely inhibit the metastasis of the 786-O RCC cells into the lungs by about 87.4% as compared to vehicle treated control animals. In addition, the lung tumor masses of mice pretreated with 2-10 mg/kg kaempferol were reduced about twofold to fourfold. These data suggested that kaempferol can play a promising role in tumor prevention and cancer metastasis inhibition.

A Phase I study of intravenous PI3K inhibitor copanlisib in Japanese patients with advanced or refractory solid tumors

PURPOSE

To evaluate the safety, tolerability, pharmacokinetics, and efficacy of the intravenously administered pan-PI3K inhibitor copanlisib in Japanese patients with advanced or refractory solid tumors.

METHODS

A Phase I open-label study in Japanese patients with advanced or refractory solid tumors was carried out. Patients received a single intravenous dose of either copanlisib 0.4 mg/kg or copanlisib 0.8 mg/kg, dosed intermittently on days 1, 8, and 15 of a 28-day cycle. Safety was monitored throughout the study. Plasma copanlisib levels were measured for pharmacokinetic analysis.

RESULTS

Ten patients were enrolled and treated; three received copanlisib 0.4 mg/kg and seven received copanlisib 0.8 mg/kg. Overall, median duration of treatment was 6.2 weeks. No patients treated at 0.4 mg/kg experienced a dose-limiting toxicity, and the maximum tolerated dose in Japanese patients was determined to be 0.8 mg/kg. Adverse events were recorded in all ten patients; the most common were hyperglycemia, hypertension, and constipation. Copanlisib pharmacokinetic exposures displayed near dose-proportionality, with no accumulation. No patients achieved a complete or partial response, and disease control rate was 40.0%.

CONCLUSIONS

Copanlisib was well tolerated in Japanese patients with advanced or refractory solid tumors, and the maximum tolerated dose was determined to be 0.8 mg/kg. Copanlisib demonstrated near dose-proportional pharmacokinetics and preliminary disease control, warranting further investigation.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01404390.

Fucoidan Induces ROS-Dependent Apoptosis in 5637 Human Bladder Cancer Cells by Downregulating Telomerase Activity via Inactivation of the PI3K/Akt Signaling Pathway

Preclinical Research Fucoidan, a sulfated polysaccharide, is a compound found in various species of seaweed that has anti-viral, anti-bacterial, anti-oxidant, anti-inflammatory, and immunomodulatory activities; however, the underlying relationship between apoptosis and anti-telomerase activity has not been investigated. Here, we report that fucoidan-induced apoptosis in 5637 human bladder cancer cells was associated with an increase in the Bax/Bcl-2 ratio, the dissipation of the mitochondrial membrane potential (MMP, Δψm), and cytosolic release of cytochrome c from the mitochondria. Under the same experimental conditions, fucoidan-treatment decreased hTERT (human telomerase reverse transcriptase) expression and the transcription factors, c-myc and Sp1. This was accompanied by decreased telomerase activity. Fucoidan-treatment also suppressed activation of the PI3K/Akt signaling pathway. Inhibition of PI3K/Akt signaling enhanced fucoidan-induced apoptosis and anti-telomerase activity. Meanwhile, fucoidan treatment increased the generation of intracellular ROS, whereas the over-elimination of ROS by N-acetylcysteine, an anti-oxidant, attenuated fucoidan-induced apoptosis, inhibition of hTERT, c-myc, and Sp1 expression, and reversed fucoidan-induced inactivation of the PI3K/Akt signaling pathway. Collectively, these data indicate that the induction of apoptosis and the inhibition of telomerase activity by fucoidan are mediated via ROS-dependent inactivation of the PI3K/Akt pathway. Drug Dev Res 78 : 37-48, 2017.   © 2016 Wiley Periodicals, Inc.

INPP4B is upregulated and functions as an oncogenic driver through SGK3 in a subset of melanomas

Inositol polyphosphate 4-phosphatase type II (INPP4B) negatively regulates PI3K/Akt signalling and has a tumour suppressive role in some types of cancers. However, we have found that it is upregulated in a subset of melanomas. Here we report that INPP4B can function as an oncogenic driver through activation of serum- and glucocorticoid-regulated kinase 3 (SGK3) in melanoma. While INPP4B knockdown inhibited melanoma cell proliferation and retarded melanoma xenograft growth, overexpression of INPP4B enhanced melanoma cell and melanocyte proliferation and triggered anchorage-independent growth of melanocytes. Noticeably, INPP4B-mediated melanoma cell proliferation was not related to activation of Akt, but was mediated by SGK3. Upregulation of INPP4B in melanoma cells was associated with loss of miRNA (miR)-494 and/or miR-599 due to gene copy number reduction. Indeed, overexpression of miR-494 or miR-599 downregulated INPP4B, reduced SGK3 activation, and inhibited melanoma cell proliferation, whereas introduction of anti-miR-494 or anti-miR-599 upregulated INPP4B, enhanced SGK3 activation, and promoted melanoma cell proliferation. Collectively, these results identify upregulation of INPP4B as an oncogenic mechanism through activation of SGK3 in a subset of melanomas, with implications for targeting INPP4B and restoring miR-494 and miR-599 as novel approaches in the treatment of melanomas with high INPP4B expression.

Sanguinarine Induces Apoptosis of Human Oral Squamous Cell Carcinoma KB Cells via Inactivation of the PI3K/Akt Signaling Pathway

Preclinical Research Sanguinarine, an alkaloid isolated from the root of Sanguinaria canadensis and other plants of the Papaveraceae family, selectively induces apoptotic cell death in a variety of human cancer cells, but its mechanism of action requires further elaboration. The present study investigated the pro-apoptotic effects of sanguinarine in human oral squamous cell carcinoma KB cells. Sanguinarine treatment increased DR5/TRAILR2 (death receptor 5/TRAIL receptor 2) expression and enhanced the activation of caspase-8 and cleavage of its substrate, Bid. Sanguinarine also induced the mitochondrial translocation of pro-apoptotic Bax, mitochondrial dysfunction, cytochrome c release to the cytosol, and activation of caspase-9 and -3. However, a pan-caspase inhibitor, z-VAD-fmk, reversed the growth inhibition and apoptosis induced by sanguinarine. Sanguinarine also suppressed the phosphorylation of phosphoinositide 3-kinase (PI3K) and Akt in KB cells, while co-treatment of cells with sanguinarine and a PI3K inhibitor revealed synergistic apoptotic effects. However, pharmacological inhibition of AMP-activated protein kinase and mitogen-activated protein kinases did not reduce or enhance sanguinarine-induced growth inhibition and apoptosis. Collectively, these findings indicate that the pro-apoptotic effects of sanguinarine in KB cells may be regulated by a caspase-dependent cascade via activation of both intrinsic and extrinsic signaling pathways and inactivation of PI3K/Akt signaling. Drug Dev Res 77 : 227-240, 2016.   © 2016 Wiley Periodicals, Inc.

"Scar-cinoma": viewing the fibrotic lung mesenchymal cell in the context of cancer biology

Lung cancer and pulmonary fibrosis are common, yet distinct, pathological processes that represent urgent unmet medical needs. Striking clinical and mechanistic parallels exist between these distinct disease entities. The goal of this article is to examine lung fibrosis from the perspective of cancer-associated phenotypic hallmarks, to discuss areas of mechanistic overlap and distinction, and to highlight profibrotic mechanisms that contribute to carcinogenesis. Ultimately, we speculate that such comparisons might identify opportunities to leverage our current understanding of the pathobiology of each disease process in order to advance novel therapeutic approaches for both. We anticipate that such "outside the box" concepts could be translated to a more precise and individualised approach to fibrotic diseases of the lung.

Efficacy of targeted AKT inhibition in genetically engineered mouse models of PTEN-deficient prostate cancer

The PI3K/AKT pathway is frequently altered in advanced human prostate cancer mainly through the loss of functional PTEN, and presents as potential target for personalized therapy. Our aim was to determine the therapeutic potential of the pan-AKT inhibitor, AZD5363, in PTEN-deficient prostate cancer. Here we used a genetically engineered mouse (GEM) model of PTEN-deficient prostate cancer to evaluate the in vivo pharmacodynamic and antitumor activity of AZD5363 in castration-naïve and castration-resistant prostate cancer. An additional GEM model, based on the concomitant inactivation of PTEN and Trp53 (P53), was established as an aggressive model of advanced prostate cancer and was used to further evaluate clinically relevant endpoints after treatment with AZD5363. In vivo pharmacodynamic studies demonstrated that AZD5363 effectively inhibited downstream targets of AKT. AZD5363 monotherapy significantly reduced growth of tumors in castration-naïve and castration-resistant models of PTEN-deficient prostate cancer. More importantly, AZD5363 significantly delayed tumor growth and improved overall survival and progression-free survival in PTEN/P53 double knockout mice. Our findings demonstrate that AZD5363 is effective against GEM models of PTEN-deficient prostate cancer and provide lines of evidence to support further investigation into the development of treatment strategies targeting AKT for the treatment of PTEN-deficient prostate cancer.

A phase 1b study of the Akt-inhibitor MK-2206 in combination with weekly paclitaxel and trastuzumab in patients with advanced HER2-amplified solid tumor malignancies

PURPOSE

Akt plays a key role in the aggressive pathogenesis of HER2+ malignancies, suggesting that Akt-inhibitors may be of therapeutic value in the treatment of HER2+ tumors. Preclinical studies demonstrate synergy between MK-2206, a selective allosteric Akt-inhibitor, with paclitaxel and trastuzumab. We aimed to evaluate the safety of this combination in patients with HER2+ malignancies.

METHODS

We conducted a phase 1b study of weekly MK-2206 in combination with weekly paclitaxel 80 mg/m(2) and trastuzumab 2 mg/kg in patients with HER2+ malignancies. Dose escalation was performed using a modified toxicity probability interval method. Molecular profiling of archived tissue samples and limited PK analyses were performed.

RESULTS

16 patients with HER2+ tumors were enrolled (12 breast, 3 gastric, 1 esophageal). 81 and 75 % had received prior trastuzumab and taxane chemotherapy, respectively. MK-2206 135 mg/week was determined to be tolerable. Three dose-limiting toxicities were observed including two grade 3 rashes and 1 grade 3 neutropenia resulting in a > 7 day delay in treatment. Grade 3/4 adverse events include neutropenia (44 %), rash (13 %), peripheral neuropathy (6 %), and depression (6 %). 10 patients (63 %) demonstrated tumor response (3 complete, 7 partial). Median duration of response was 6 months. Exploratory analyses identified STARD3, TM7SF2, and G3BP1 as potential biomarkers of response.

CONCLUSIONS

MK-2206 at a dose of 135 mg/week in combination with weekly paclitaxel and trastuzumab is safe and well tolerated, and is the recommended phase 2 dose for this combination. Preliminary data indicate significant clinical activity in patients with HER2+ tumors despite prior HER2-directed therapy.

Akt inhibitors in cancer treatment: The long journey from drug discovery to clinical use (Review)

Targeted cancer therapies are used to inhibit the growth, progression, and metastasis of the tumor by interfering with specific molecular targets and are currently the focus of anticancer drug development. Protein kinase B, also known as Akt, plays a central role in many types of cancer and has been validated as a therapeutic target nearly two decades ago. This review summarizes the intracellular functions of Akt as a pivotal point of converging signaling pathways involved in cell growth, proliferation, apoptotis and neo‑angiogenesis, and focuses on the drug design strategies to develop potent anticancer agents targeting Akt. The discovery process of Akt inhibitors has evolved from adenosine triphosphate (ATP)‑competitive agents to alternative approaches employing allosteric sites in order to overcome the high degree of structural similarity between Akt isoforms in the catalytic domain, and considerable structural analogy to the AGC kinase family. This process has led to the discovery of inhibitors with greater specificity, reduced side-effects and lower toxicity. A second generation of Akt has inhibitors emerged by incorporating a chemically reactive Michael acceptor template to target the nucleophile cysteines in the catalytic activation loop. The review outlines the development of several promising drug candidates emphasizing the importance of each chemical scaffold. We explore the pipeline of Akt inhibitors and their preclinical and clinical examination status, presenting the potential clinical application of these agents as a monotherapy or in combination with ionizing radiation, other targeted therapies, or chemotherapy.

Sustained proliferation in cancer: Mechanisms and novel therapeutic targets

Proliferation is an important part of cancer development and progression. This is manifest by altered expression and/or activity of cell cycle related proteins. Constitutive activation of many signal transduction pathways also stimulates cell growth. Early steps in tumor development are associated with a fibrogenic response and the development of a hypoxic environment which favors the survival and proliferation of cancer stem cells. Part of the survival strategy of cancer stem cells may manifested by alterations in cell metabolism. Once tumors appear, growth and metastasis may be supported by overproduction of appropriate hormones (in hormonally dependent cancers), by promoting angiogenesis, by undergoing epithelial to mesenchymal transition, by triggering autophagy, and by taking cues from surrounding stromal cells. A number of natural compounds (e.g., curcumin, resveratrol, indole-3-carbinol, brassinin, sulforaphane, epigallocatechin-3-gallate, genistein, ellagitannins, lycopene and quercetin) have been found to inhibit one or more pathways that contribute to proliferation (e.g., hypoxia inducible factor 1, nuclear factor kappa B, phosphoinositide 3 kinase/Akt, insulin-like growth factor receptor 1, Wnt, cell cycle associated proteins, as well as androgen and estrogen receptor signaling). These data, in combination with bioinformatics analyses, will be very important for identifying signaling pathways and molecular targets that may provide early diagnostic markers and/or critical targets for the development of new drugs or drug combinations that block tumor formation and progression.

Results of an abbreviated phase-II study with the Akt Inhibitor MK-2206 in Patients with Advanced Biliary Cancer

Biliary cancers (BC) are rare, chemoresistant and are associated with a poor prognosis. Targeting the Akt pathway is of significance in BC. We hypothesized that the allosteric inhibitor MK-2206 will be active in BC. This was a multi-institutional phase II study of MK-2206 given to patients with advanced, refractory BC. The primary end point was overall response rate. We also characterized pharmacokinetic profiles of MK-2206 in these patients and explored its potential correlation with clinical outcomes. Eight patients were enrolled prior to early termination of the trial. All patients had received prior systemic therapy. The best response observed was stable disease, exceeding 12 weeks in two patients. Toxicities were mild and tolerable. MK-2206 exhibited a pharmacokinetic profile with an apparent slow absorption followed by biphasic elimination in these patients with BC. No significant association was observed between the pharmacokinetic properties of MK-2206 and clinical outcomes. MK-2206 as a single-agent in BC is tolerable with pharmacokinetic properties similar to patients with other solid tumors. No clinical activity was observed in this limited population. Further development of Akt inhibitors may need to focus on combinations with other molecular targeted agents, conventional cytotoxic chemotherapy and prospective patient selection.

So-Cheong-Ryong-Tang induces apoptosis through activation of the intrinsic and extrinsic apoptosis pathways, and inhibition of the PI3K/Akt signaling pathway in non-small-cell lung cancer A549 cells

Background

So-Cheong-Ryong-Tang (SCRT), a traditional Korean medicine containing eight species of medicinal plant, has been used to treat patients with bronchial asthma and allergic rhinitis for hundreds of years; however, its anti-cancer potential is poorly understood. The present study was designed to evaluate the apoptotic effect of SCRT against human non-small-cell lung cancer (NSCLC) A549 cells.

Methods

The effects of SCRT on cell growth and viability were evaluated by trypan blue dye exclusion and 3-(4, 5-dimethyl-thiazol-2-yl)-2, 5-diphenyl tetrazoliumbromide (MTT) assays, respectively. Apoptosis was detected using 4,6-diamidino-2-phenyllindile (DAPI) staining, agarose gel electrophoresis and flow cytometry. The protein levels were determined by Western blot analysis. Caspase activity was measured using a colorimetric assay.

Results

SCRT treatment resulted in significantly decreased A549 cell growth and viability by induction of apoptosis. SCRT induced the translocation of pro-apoptotic Bax to the mitochondria, mitochondrial membrane permeabilization, cytochrome c release from mitochondria to cytosol, and activated caspase-9 and caspase-3. SCRT also increased death receptor-associated ligands and enhanced the activation of caspase-8 and cleavage of its substrate Bid. However, the pan-caspases inhibitor significantly blocked the SCRT-induced apoptosis, suggesting that it is a caspase-dependent pathway. In addition, SCRT suppressed the phosphorylation of phosphoinositide 3-kinase (PI3K) and Akt, and treatment with a potent inhibitor of PI3K further increased the apoptotic activity of SCRT.

Conclusions

These findings suggest that SCRT may play its anti-cancer actions partly through a suppression of the PI3K/Akt signal pathway in A549 cells, and further in vivo studies on the potential of SCRT for prevention and therapy of NSCLCs are warranted.

Leptin signaling molecular actions and drug target in hepatocellular carcinoma

Previous reports indicate that over 13 different tumors, including hepatocellular carcinoma (HCC), are related to obesity. Obesity-associated inflammatory, metabolic, and endocrine mediators, as well as the functioning of the gut microbiota, are suspected to contribute to tumorigenesis. In obese people, proinflammatory cytokines/chemokines including tumor necrosis factor-alpha, interleukin (IL)-1 and IL-6, insulin and insulin-like growth factors, adipokines, plasminogen activator inhibitor-1, adiponectin, and leptin are found to play crucial roles in the initiation and development of cancer. The cytokines induced by leptin in adipose tissue or tumor cells have been intensely studied. Leptin-induced signaling pathways are critical for biological functions such as adiposity, energy balance, endocrine function, immune reaction, and angiogenesis as well as oncogenesis. Leptin is an activator of cell proliferation and anti-apoptosis in several cell types, and an inducer of cancer stem cells; its critical roles in tumorigenesis are based on its oncogenic, mitogenic, proinflammatory, and pro-angiogenic actions. This review provides an update of the pathological effects of leptin signaling with special emphasis on potential molecular mechanisms and therapeutic targeting, which could potentially be used in future clinical settings. In addition, leptin-induced angiogenic ability and molecular mechanisms in HCC are discussed. The stringent binding affinity of leptin and its receptor Ob-R, as well as the highly upregulated expression of both leptin and Ob-R in cancer cells compared to normal cells, makes leptin an ideal drug target for the prevention and treatment of HCC, especially in obese patients.

The hepatitis B virus (HBV) HBx protein activates AKT to simultaneously regulate HBV replication and hepatocyte survival

Chronic infection with hepatitis B virus (HBV) is a risk factor for developing liver diseases such as hepatocellular carcinoma (HCC). HBx is a multifunctional protein encoded by the HBV genome; HBx stimulates HBV replication and is thought to play an important role in the development of HBV-associated HCC. HBx can activate the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway in some cell lines; however, whether HBx regulates PI3K/AKT signaling in normal hepatocytes has not been evaluated. In studies described here, we assessed HBx activation of PI3K/AKT signaling in an ex vivo model of cultured primary hepatocytes and determined how this HBx activity affects HBV replication. We report that HBx activates AKT in primary hepatocytes and that the activation of AKT decreases HBV replication and HBV mRNA and core protein levels. We show that the transcription factor hepatocyte nuclear factor 4α (HNF4α) is a target of HBx-regulated AKT, and we link HNF4α to HBx-regulated AKT modulation of HBV transcription and replication. Although we and others have shown that HBx stimulates and is likely required for HBV replication, we now report that HBx also activates signals that can diminish the overall level of HBV replication. While this may seem counterintuitive, we show that an important effect of HBx activation of AKT is inhibition of apoptosis. Consequently, our studies suggest that HBx balances HBV replication and cell survival by stimulating signaling pathways that enhance hepatocyte survival at the expense of higher levels of HBV replication.

IMPORTANCE

Chronic hepatitis B virus (HBV) infection is a common cause of the development of liver cancer. Regulation of cell signaling pathways by the HBV HBx protein is thought to influence the development of HBV-associated liver cancer. HBx stimulates, and may be essential for, HBV replication. We show that HBx activates AKT in hepatocytes to reduce HBV replication. While this seems contradictory to an essential role of HBx during HBV replication, HBx activation of AKT inhibits hepatocyte apoptosis, and this may facilitate persistent, noncytopathic HBV replication. AKT regulates HBV replication by reducing the activity of the transcription factor hepatocyte nuclear factor 4α (HNF4α). HBx activation of AKT may contribute to the development of liver cancer by facilitating persistent HBV replication, augmenting the dedifferentiation of hepatocytes by inhibiting HNF4α functions, and activating AKT-regulated oncogenic pathways. AKT-regulated factors may provide therapeutic targets for inhibiting HBV replication and the development of HBV-associated liver cancer.

Hirsutenone in Alnus extract inhibits akt activity and suppresses prostate cancer cell proliferation

Although specific compounds found in some East Asian traditional medicines have been shown to exhibit bioactive properties, their molecular mechanisms of action remain elusive. The bark of the Alnus species has been used for the treatment of various pathological conditions including hemorrhage, alcoholism, fever, diarrhea, skin diseases, inflammation, and cancer in East Asia for centuries. In this study, we show that hirsutenone, a bioactive compound in Alnus japonica, exhibits anti-cancer effects against prostate cancer through a direct physical inhibition of Akt1/2. Hirsutenone suppressed anchorage-dependent and independent cell growth of PC3 and LNCaP human prostate cancer cells. Annexin V and Propidium iodide (PI) staining results demonstrated that hirsutenone strongly induces apoptotic cell death in both PC3 and LNCaP cells. Furthermore, treatment of hirsutenone attenuated phosphorylation of mammalian target of rapamycin (mTOR), a downstream substrate of Akt, without affecting Akt phosphorylation. Kinase and pull-down assay results clearly show that hirsutenone inhibits Akt1 and 2 by direct binding in an adenosine triphosphate (ATP)-noncompetitive manner in vitro and ex vivo. Our results show that hirsutenone suppresses human prostate cancer by targeting Akt1 and 2 as a key component to explain for anti-cancer activity of Alnus species.

Preferential effect of akt2-dependent signaling on the cellular viability of ovarian cancer cells in response to EGF

OBJECTIVE

Overexpression of the epidermal growth factor receptor (EGFR) is associated with the malignant phenotype in many cancers including ovarian cancer, which leads to increased cell proliferation and survival. In spite of emerging EGFR inhibitors as a potentially useful agent, they are largely ineffective in patients with advanced or recurrent ovarian cancers. Since Akt as a key downstream factor of EGFR is highly activated in some high grade serous ovarian tumors, the augmented Akt activation may attribute to irregular EGFR-mediated signaling observed in ovarian cancer. Here we investigated the differential effect of Akt on the EGF-induced cell viability in a panel of ovarian cancer cell lines.

METHODS

Cellular viability assay and western blot analysis were used to measure cell viability and expression levels of proteins, respectively. Knockdown of Akt was achieved with siRNA and stable transfection of expression vectors was performed.

RESULTS

Cellular viability increased in OVCAR-3 ovarian cancer cells exposed to EGF, but little to no difference was observed in the 5 other ovarian cancer cells including SKOV-3 cells despite of the expression of EGFR. In OVCAR-3 cells, EGF activated Erk and Akt, but an Erk inhibitor had no impact on cellular viability. On the other hand, the EGFR and PI3K inhibitors decreased EGF-induced cellular viability, indicating the involvement of Akt signaling. Although EGF activated Erk in SKOV-3 cells, the Akt activation was very weak as compared to OVCAR-3 cells. Furthermore, we observed a different expression of Akt isoforms: Akt1 was constitutively expressed in all tested ovarian cancer cells, while Akt3 was little expressed. Interestingly, Akt2 was highly expressed in OVCAR-3 cells. Knockdown of Akt2 blocked EGF-induced OVCAR-3 cell viability whereas knockdown for Akt1 and Erk1/2 had no significant effect. Stable transfection of Akt2 into SKOV-3 cells phosphorylated more Akt and enhanced cell viability in response to EGF.

CONCLUSIONS

Akt2-dependent signaling appears to play an important role in EGFR-mediated cellular viability in ovarian cancer and targeting specific Akt isoform may provide a potential therapeutic approach for EGFR-expressing ovarian cancers.

Oncogenic role and therapeutic target of leptin signaling in colorectal cancer

INTRODUCTION

Obesity is characterized by high secretion of several cytokines from adipose tissue and is a recognized risk factor for many cancers. Among these cytokines, leptin mainly produced by adipose tissue and cancer cells is the most studied adipokine. Leptin is an activator of cell proliferation, an antiapoptotic molecule and inducer of cancer stem cells in many cell types, and its critical roles in obesity-related tumorigenesis are based on its oncogenic, mitogenic, pro-inflammatory and pro-angiogenic actions.

AREAS COVERED

These leptin-induced signals and action are critical for their biological effects on energy balance, adiposity, endocrine systems, immunity, angiogenesis as well as oncogenesis. This review focuses on the up-to-date knowledge on the oncogenic role of leptin signaling, clinical significance and specific drug target development in colorectal cancer (CRC). Additionally, leptin-induced angiogenic ability and molecular mechanisms in CRC cells are discussed.

EXPERT OPINION

Stringent binding affinity of leptin/Ob-R and overexpression of leptin/Ob-R and their targets in cancer cells make it a unique drug target for prevention and treatment of CRC, particularly in obesity colorectal patients.

Targeting the genetic alterations of the PI3K-AKT-mTOR pathway: its potential use in the treatment of bladder cancers

Urothelial carcinoma of the bladder is the most frequent tumor of the urinary tract and represents the fifth cause of death by cancer worldwide. The current first line chemotherapy is a combination of cisplatin and gemcitabine with median survival not exceeding 15months. Vinflunine is the only drug approved by EMEA as second-line treatment and few progresses have been made for the past 20years to increase the survival of metastatic patients, especially those who are not eligible for cisplatin-based regimen. The recent studies characterizing the genetic background of urothelial cancers of the bladder, revealed chromosomal alterations that are not seen at the same level in other types of cancers. This is especially the case for mutations of genes involved in the PI3K/AKT/mTOR signaling pathway that occupies a major place in the etiology of these tumors. Here, we describe the mutations leading to constitutive activation of the PI3K/AKT/mTOR pathway and discuss the potential use of the different classes of PI3K/AKT/mTOR inhibitors in the treatment of urothelial bladder cancers. Despite the recent pivotal study evidencing specific mutations of TSC1 in bladder cancer patients responding to everolimus and the encouraging results obtained with other derivatives than rapalogs, few clinical trials are ongoing in bladder cancers. Because of the genetic complexity of these tumors, the cross-talks of the PI3K/AKT/mTOR pathway with other pathways, and the small number of eligible patients, it will be of utmost importance to carefully choose the drugs or drug combinations to be further tested in the clinic.

Prognostic value of phospho-Akt in patients with non-small cell lung carcinoma: a meta-analysis

Previous studies have been inconsistent with respect to the reported associations between phospho-Akt (p-Akt) overexpression and lung cancer prognosis. In this study, we conducted a systematic review and meta-analysis to assess the prognostic value of p-Akt in patients with non-small cell lung carcinoma (NSCLC). Relevant articles were identified by searching MEDLINE. Hazard risks (HRs) from individual studies were calculated and pooled by using a random-effect model, and heterogeneity and publication bias analyses were also performed. Finally, 18 studies comprising 2,353 patients were included in the meta-analysis. p-Akt overexpression was associated with worse survival in NSCLC patients, and the pooled HRs for all the studies was 1.38 (95% confidence interval [CI]: 1.11-1.70; p<0.01). After subgroup analysis, the association was strengthened in the surgery treatment group, with an HR of 1.44 (95% CI: 1.19-1.75; p<0.01), while in the tyrosine kinase inhibitors treatment group, the statistical significance disappeared (HR: 1.22, 95% CI: 0.70-2.14; p=0.48). The HR in cases of early stage disease (I-III) was 1.35 (95% CI: 1.08-1.69; p=0.04); however, in cases of late stage disease (III-IV), the association became non-significant (HR: 1.22, 95% CI: 0.64-2.33; p=0.54). Our results suggest that there was a significantly inverse association between p-Akt overexpression and the prognosis of NSCLC patients, and that this association appeared to be limited in early-stage patients who underwent surgery.

Anticancer compound plumbagin and its molecular targets: a structural insight into the inhibitory mechanisms using computational approaches

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) is a naphthoquinone derivative from the roots of plant Plumbago zeylanica and belongs to one of the largest and diverse groups of plant metabolites. The anticancer and antiproliferative activities of plumbagin have been observed in animal models as well as in cell cultures. Plumbagin exerts inhibitory effects on multiple cancer-signaling proteins, however, the binding mode and the molecular interactions have not yet been elucidated for most of these protein targets. The present study is the first attempt to provide structural insights into the binding mode of plumbagin to five cancer signaling proteins viz. PI3Kγ, AKT1/PKBα, Bcl-2, NF-κB, and Stat3 using molecular docking and (un)binding simulation analysis. We validated plumbagin docking to these targets with previously known important residues. The study also identified and characterized various novel interacting residues of these targets which mediate the binding of plumbagin. Moreover, the exact modes of inhibition when multiple mode of inhibition existed was also shown. Results indicated that the engaging of these important interacting residues in plumbagin binding leads to inhibition of these cancer-signaling proteins which are key players in the pathogenesis of cancer and thereby ceases the progression of the disease.

Inhibition of cell growth by BrMC through inactivation of Akt in HER-2/neu-overexpressing breast cancer cells

We previously reported that chrysin (ChR) and its analogs induced cell cycle arrest and apoptosis in human estrogen receptor-positive/-negative breast cancer cells. However, it was unknown whether 8-bromo-7-methoxychrysin (BrMC), a novel synthetic ChR analog, inhibited the cell growth of human epidermal growth factor receptor 2 (HER-2)/neu-overexpressing breast cancers. In the present study, it was demonstrated that BrMC preferentially inhibited the cell viability of HER-2/neu-overexpressing MDA-MB-453 and BT-474 cells. Western blot analysis revealed that HER-2/neu expression and tyrosine phosphorylation were inhibited by BrMC in a concentration-dependent manner; whereas the proteasome inhibitor, MG-132, significantly prevented BrMC-induced HER-2/neu depletion and cell death in MDA-MB-453 cells. This directly indicated that BrMC-induced HER-2/neu depletion and cell growth inhibition was mediated by a proteasomal pathway. BrMC significantly downregulated the expression of cyclin D1, cyclin E and CDK4, followed by the suppression of protein kinase B phosphorylation and downstream effectors, GSK-3β and β-catenin. A colony formation assay also confirmed the growth-inhibitory effects of BrMC. Thus, these findings clearly demonstrate the anticancer activity of BrMC against human HER-2/neu-overexpressing breast cancer cells. Thus, these findings clearly demonstrate the anticancer activity of BrMC against human HER 2/neu-overexpressing breast cancer cells, and highlight BrMC as a promising candidate for breast cancer therapy.

Protective Effects of Shen-Yuan-Dan, a Traditional Chinese Medicine, against Myocardial Ischemia/Reperfusion Injury In Vivo and In Vitro

Objectives. The study was to investigate the effects and mechanisms of Shen-Yuan-Dan (SYD) pharmacological postconditioning on myocardial ischemia/reperfusion (I/R) injury. Methods. In the in vivo experiment, myocardial injury markers and histopathology staining were examined. In the in vitro experiment, cell viability and cell apoptosis were, respectively, detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays and Hoechst 33342 fluorochrome staining. The protein expressions of Bcl-2 and Bax were determined by immunocytochemistry assay. Results. Both low and high doses of SYD protected myocardium against I/R injury in rat model by reducing lactic dehydrogenase (LDH) and creatine kinase-MB (CK-MB) activity and malondialdehyde (MDA) content, increasing superoxide dismutase (SOD) activity and attenuating histopathology injury. Meanwhile, in the in vitro experiment, SYD promoted cell viability and inhibited the cardiomyocyte apoptosis. The level of Bcl-2 protein was restored to the normal level by SYD pharmacological postconditioning. In contrast, the Bax protein level was markedly reduced by SYD pharmacological postconditioning. These effects of SYD were inhibited by LY294002. Conclusions. The results of this study suggested that SYD pharmacological postconditioning has protective effects against myocardial I/R injury in both in vivo and in vitro models, which are related to activating the phosphatidylinositol 3-kinase/Akt (PI3K/Akt) pathway.

Regulation of angiogenesis via Notch signaling in breast cancer and cancer stem cells

Breast cancer angiogenesis is elicited and regulated by a number of factors including the Notch signaling. Notch receptors and ligands are expressed in breast cancer cells as well as in the stromal compartment and have been implicated in carcinogenesis. Signals exchanged between neighboring cells through the Notch pathway can amplify and consolidate molecular differences, which eventually dictate cell fates. Notch signaling and its crosstalk with many signaling pathways play an important role in breast cancer cell growth, migration, invasion, metastasis and angiogenesis, as well as cancer stem cell (CSC) self-renewal. Therefore, significant attention has been paid in recent years toward the development of clinically useful antagonists of Notch signaling. Better understanding of the structure, function and regulation of Notch intracellular signaling pathways, as well as its complex crosstalk with other oncogenic signals in breast cancer cells will be essential to ensure rational design and application of new combinatory therapeutic strategies. Novel opportunities have emerged from the discovery of Notch crosstalk with inflammatory and angiogenic cytokines and their links to CSCs. Combinatory treatments with drugs designed to prevent Notch oncogenic signal crosstalk may be advantageous over λ secretase inhibitors (GSIs) alone. In this review, we focus on the more recent advancements in our knowledge of aberrant Notch signaling contributing to breast cancer angiogenesis, as well as its crosstalk with other factors contributing to angiogenesis and CSCs.

The anti-cancer activities of Vernonia amygdalina extract in human breast cancer cell lines are mediated through caspase-dependent and p53-independent pathways

Breast cancer is currently the leading cause of cancer-related deaths among women globally. Notably, medicinal plant extracts may be a potential source for treatments of breast cancer. Vernonia amygdalina (VA) is a woody shrub reported to have not only diverse therapeutic effects but also anti-cancer properties. However, current research about the mechanisms of the anti-cancer potential of VA has been limited. This study aimed to investigate the mechanisms of action of VA that underlie its anti-cancer effects in human breast cancer cell lines (MCF-7 and MDA-MB-231 cells). Results from MTT assay revealed that VA inhibits the proliferation of MCF-7 and MDA-MB-231, in a time- and dose-dependent manner. The underlying mechanism of this growth inhibition involved the stimulation of cell-type specific G1/S phase cell cycle arrest in only MCF-7 cells, and not in MDA-MB-231 cells. While the growth arrest was associated with increased levels of p53 and p21, and a concomitant decrease in the levels of cyclin D1 and cyclin E, it was shown that VA causes cell cycle arrest through a p53-independent pathway as tested by the wild type p53 inhibitor, pifithrin-α. Furthermore, this study revealed that VA induces apoptosis in the two cell lines, as indicated by the increase in Annexin V-positive cells and sub-G1 population, and that this VA-induced apoptosis occurred through both extrinsic and intrinsic apoptotic pathways. The apoptosis in MCF-7 cells was also likely to be caspase-dependent and not p53 transcriptional-dependent. Given that approximately 70% of diagnosed breast cancers express ER-α, a crucial finding was that VA inhibits the expression of ER-α and its downstream player, Akt, highlighting the potential clinical significance of VA. Moreover, VA exhibits synergism when combined with doxorubicin, suggesting that it can complement current chemotherapy. Overall, this study demonstrates the potential applications of VA as an anti-cancer drug for breast cancer treatment.

Isoangustone A, a novel licorice compound, inhibits cell proliferation by targeting PI3K, MKK4, and MKK7 in human melanoma

Licorice root is known to possess various bioactivities, including anti-inflammatory and anticancer effects. Glycyrrhizin, a triterpene compound, is the most abundant constituent of dried licorice root. However, high intake or long-term consumption of glycyrrhizin causes several side effects, such as hypertension, hypertensive encephalopathy, and hypokalemia. Therefore, finding additional active compounds other than glycyrrhizin in licorice that exhibit anticancer effects is worthwhile. We found that isoangustone A (IAA), a novel flavonoid from licorice root, suppressed proliferation of human melanoma cells. IAA significantly blocked cell-cycle progression at the G1-phase and inhibited the expression of G1-phase regulatory proteins, including cyclins D1 and E in the SK-MEL-28 human melanoma cell line. IAA suppressed the phosphorylation of Akt, GSK-3β, and JNK1/2. IAA also bound to phosphoinositide 3-kinase (PI3K), MKK4, and MKK7, strongly inhibiting their kinase activities in an ATP-competitive manner. Moreover, in a xenograft mouse model, IAA significantly decreased tumor growth, volume, and weight of SK-MEL-28 xenografts. Collectively, these results suggest that PI3K, MKK4, and MKK7 are the primary molecular targets of IAA in the suppression of cell proliferation. This insight into the biologic actions of IAA provides a molecular basis for the potential development of a new chemotherapeutic agent.