Regulation Of Normal Cell Growth Research Articles

Abstract 2046: Targeting cellular models of glioblastoma versus non-target and off-target cell populations using U87-MG membrane lipid-modified nanoliposomes

Abstract Background: Glioblastoma Multiform (GBM) is an aggressive and malignant form of brain cancer known for its invasiveness and significant heterogenicity. The majority of GBM cases are linked to genetic mutations (ie. TP53, EGFR, and PTEN), which disrupt the normal regulation of cell growth and division, resulting in uncontrolled cell proliferation. The utilization of nanoparticles presents a promising approach for addressing the complexities associated with selective drug delivery to GMB and treatment. The purpose of this study was to investigate the effect of including U87-MG membrane lipid extracts in nanoliposomes using target, non-target, and normal healthy cellular populations in vitro. Methods: The nanoliposomes employed for the experiments included various ratios of U87-MG lipid extracts (lipids derived from U87-MG cells), DOPC, Cholesterol, and DPPE-Rhodamine for fluorescence studies. The particle size and zeta potential values were measured and monitored throughout for consistency. Fluorescence intensity values (arbitrary units) were used to assess extent of cell binding, and uptake at the various time points. In vitro studies were employed to evaluate the cellular uptake activity of U87-MG-modified nanoliposome preparations using mixed ratios and compositions of lipid materials. Cell lines employed were, LN-18 (human glioma), T98G (human glioma), U87-MG (human glioma), 4TI (murine breast), and HBEC-5i (normal healthy) cells. Results: The average size for the nanoliposomes (with and without lipid extract) fell within the range of 110 to 220 nm, while the zeta potential for the CLENs was negatively-charged. In vitro studies revealed that the inclusion of U87MG lipid extract in nanoliposomes increased cellular uptake in glioma cells when compared to control. Current investigations focus on different microenvironments, including non-target and off target cell populations. The findings from the cellular uptake analyses to date suggest that the in vitro cellular uptake of the CLENs varied in accordance with the total lipid extract content for all cell lines. Citation Format: Kaylee Janton, Duha Baamir, Aesha Patel, Sheren Boco, Robert Campbell. Targeting cellular models of glioblastoma versus non-target and off-target cell populations using U87-MG membrane lipid-modified nanoliposomes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2046.

Crosstalk between Circadian Rhythm Dysregulation and Tumorigenesis, Tumor Metabolism and Tumor Immune Response.

Circadian rhythm is a self-regulating 24-hour system that synchronizes with the day and night cycle in organisms. The regulation of this system is controlled by clock genes, which function to harmoniously express molecular levels that facilitate the orderly coordination of various cellular processes, such as sleep, metabolism, endocrine function, cell proliferation and immunity. The root cause of tumorigenesis is that the body loses its normal regulation of cell growth at the genetic level. Long-term disruptions in circadian rhythms caused by factors such as shift work, jet lag, and unstable sleep patterns can impact cellular health, leading to various health problems, including cancer. Circadian rhythm controls most cellular functions related to cancer progression, which has a significant impact on the ability of immune cells to detect cancer cells and promote their clearance and has crucial implication for future tumor immunotherapy. This article aims to review the crosstalk between dysregulation of circadian rhythm and tumorigenesis, tumor metabolism, and immune response. Additionally, we discuss the role of circadian rhythm disruption in tumor therapy, highlighting its potential to optimize treatment timing and improve therapeutic outcomes.

The role of circadian rhythm in breast cancer, lung cancer, and colorectal cancer

Circadian rhythm is a biological rhythm system with a self-regulating function and a 24-hour cycle that is synchronized with the alternation of day and night and is driven by circadian clock genes and clock-control genes. The circadian clock governs and controls processes like immune, metabolism, endocrine, cell division and proliferation, apoptosis, and sleep, allowing cells, tissues, and organs to carry out different living activities in an organized and coordinated way. The root cause of tumors is gene mutations that cause the body to lose its normal regulation of cell growth. According to studies, cancer and problems of biological rhythm are tightly linked. Related epidemiological studies are related to the occurrence and inhibition of tumors by circadian rhythms the molecular mechanism of action has become a hot issue. In this paper, combined with relevant research at home and abroad, we focus on the specific association between circadian rhythm and the high occurrence of breast cancer, lung cancer, and colorectal cancer in three populations, as well as the part circadian clocks play at the molecular level in tumor development and progression, and discuss the timing of cancer. Therapeutics is a novel therapeutic field that has the potential to increase efficacy and minimize negative effects. A sounder theoretical foundation for the identification, management, and prognosis of clinical cancers will be made possible by the clarification of the circadian clock in cancer.

A multidisciplinary approach in the management of a patient with familial von Recklinghausen’s disease: A case report and review of literature

Abstract Neurofibromatosis type 1 (NF1), also known as von Recklinghausen’s disease (VRD), is an autosomal dominant genetic disorder caused by gene mutations located on chromosome 17. Of these, 90% are point mutations, and the rest have larger deletions, affecting nearly one in every 3500 births. The same gene is responsible for the synthesis of a protein known as neurofibromin, which helps in the regulation of normal cell growth. This disorder is characterized by the development of swellings all over the body along the distribution of nerves, skin changes, visual abnormalities, and bony deformities in some individuals. In addition to this, it is also a neoplastic predisposition syndrome that is associated with both benign and malignant tumors of the brain and spinal cord. In 20% of the cases with NF1, it is associated with gliomagenesis, which often affects the optic pathway and brain stem. In the early phases, it is associated with benign gliomas, whereas in the later stages, it is associated with malignant gliomas. But nevertheless, high-grade gliosarcomas (grade IV) of the brain are rare entities with reported higher risks in both children and adults. We report a case of familial NF1 (VRD) in a patient with an associated high-grade right parieto-temporo-occipital lobe glioma. Surgical excision via gross total resection is the mainstay of treatment. However, a multidisciplinary approach is also vital. This is described here, whereby timely intervention from neurology, ophthalmology, radiology, orthopedics, neurosurgery, and radiotherapy led to the successful management of the patient.

Matrix metalloproteinase 2 is a target of the RAN-GTP pathway and mediates migration, invasion and metastasis in human breast cancer

RAS-related nuclear protein(RAN) is a nuclear shuttle and normally regulates events in the cell cycle. When overexpressed in cultured cells, it causes increases in cell migration/invasion in vitro and its overexpression is associated with early breast cancer patient deaths in vivo. However, the underlying mechanism is unknown. The effect of RAN overexpression on potential targets MMP2, ATF3, CXCR3 was investigated by Real-Time PCR/Western blots in the triple receptor negative breast cancer(TRNBC) cell line MDA-MB231 and consequent biological effects were measured by cell adhesion, cell migration and cell invasion assays. Results showed that knockdown of RAN lead to a reduction of MMP2 and its potential regulators ATF3 and CXCR3. Moreover, knockdown of ATF3 or CXCR3 downregulated MMP2 without affecting RAN, indicating that RAN regulates MMP2 through ATF3 and CXCR3. Knockdown of RAN and MMP2 reduced cell adhesion, cell migration and cell growth in agar, whilst overexpression of MMP2 reversed the knockdown of RAN. Furthermore, immunohistochemical staining for RAN and MMP2 are positively associated with each other in the same tumour and separately with patient survival times in breast cancer specimens, suggesting that a high level of RAN may be a pre-requisite for MMP2 overexpression and metastasis. Moreover, positive immunohistochemical staining for both RAN and MMP-2 reduces further patient survival times over that for either protein separately. Our results suggest that MMP2 expression can stratify progression of breast cancers with a high and low incidence of RAN, both RAN and MMP2 in combination can be used for a more accurate patient prognosis. Simple summaryRan is an important regulator of normal cell growth and behaviour. We have established in cell line models of breast cancer (BC) a molecular pathway between RAN and its protein-degrading effector MMP-2 and properties related to metastasis in culture. Using immunohistochemistry (IHC) staining of primary BCs, we have shown that RAN and MMP-2 are on their own significantly associated with patient demise from metastatic BC. Moreover, when staining for MMP-2 is added to that for RAN in the primary tumours, there is a significant decrease in patient survival time over that for either protein alone. Thus a combination of staining for RAN and MMP2 is an excellent marker for poor prognosis in breast cancer.

The Distinct Roles of Transcriptional Factor KLF11 in Normal Cell Growth Regulation and Cancer as a Mediator of TGF-β Signaling Pathway.

KLF11 (Krüppel-like factor 11) belongs to the family of Sp1/Krüppel-like zinc finger transcription factors that play important roles in a variety of cell types and tissues. KLF11 was initially described as a transforming growth factor-beta (TGF-β) inducible immediate early gene (TIEG). KLF11 promotes the effects of TGF-β on cell growth control by influencing the TGFβ–Smads signaling pathway and regulating the transcription of genes that induce either apoptosis or cell cycle arrest. In carcinogenesis, KLF11 can show diverse effects. Its function as a tumor suppressor gene can be suppressed by phosphorylation of its binding domains via oncogenic pathways. However, KLF 11 can itself also show tumor-promoting effects and seems to have a crucial role in the epithelial–mesenchymal transition process. Here, we review the current knowledge about the function of KLF11 in cell growth regulation. We focus on its transcriptional regulatory function and its influence on the TGF-β signaling pathway. We further discuss its possible role in mediating crosstalk between various signaling pathways in normal cell growth and in carcinogenesis.

Helicobacter pylori as an oncogenic pathogen, revisited.

Gastric cancer is an inflammation-associated malignancy aetiologically related to infection with the bacterium, Helicobacter pylori, which is considered a necessary but insufficient cause. Unless treated, H. pylori causes life-long acute and chronic gastric inflammation resulting in progressive gastric mucosal damage that may result in gastric cancer. The rate of progression from superficial gastritis, to an atrophic metaplastic mucosa, and ultimately to cancer relates to the virulence of the infecting H. pylori as well as host and environmental factors. H. pylori virulence is a reflection of its propensity to cause severe gastric inflammation. Both mucosal inflammation and H. pylori can cause host genomic instability, including dysregulation of DNA mismatch repair, stimulation of expression of activation-induced cytidine deaminase, abnormal DNA methylation and dysregulation of micro RNAs, which may result in an accumulation of mutations and loss of normal regulation of cell growth. The difference in cancer risk between the most and least virulent H. pylori strain is only approximately 2-fold. Overall, none of the putative virulence factors identified to date have proved to be disease-specific. The presence, severity, extent and duration of inflammation appear to be the most important factors and current evidence suggests that any host, environmental or bacterial factor that reliably enhances the inflammatory response to the H. pylori infection increases the risk of gastric cancer.

Somatic overgrowth disorders of the PI3K/AKT/mTOR pathway & therapeutic strategies.

The phosphatidylinositol-3-kinase (PI3K)/AKT/mTOR signaling pathway plays an essential role in regulation of normal cell growth, metabolism, and survival. Somatic activating mutations in the PI3K/AKT/mTOR pathway are among the most common mutations identified in cancer, and have been shown to cause a spectrum of overgrowth syndromes including PIK3CA-Related Overgrowth Spectrum, Proteus syndrome, and brain overgrowth conditions. Clinical findings in these disorders may be isolated or multiple, including sporadic or mosaic overgrowth (adipose, skeletal, muscle, brain, vascular, or lymphatic), and skin abnormalities (including epidermal nevi, hyper-, and hypopigmented lesions), and have the potential risk of tumorigenesis. Key negative regulators of the PI3K-AKT signaling pathway include PTEN and TSC1/TSC2 and germline loss-of function mutations of these genes are established to cause PTEN Hamartoma Tumor Syndrome and Tuberous Sclerosis Complex. Mosaic forms of these conditions lead to increased activation of PI3K and mTOR at affected sites and there is phenotypic overlap between these conditions. All are associated with significant morbidity with limited options for treatment other than symptomatic therapies and surgeries. As dysregulation of the PI3K/AKT/mTOR pathway has been implicated in cancer, several small molecule inhibitors targeting different components of the PI3K/AKT/mTOR signaling pathway are under clinical investigation. The development of these therapies brings closer the prospect of targeting treatment for somatic PI3K/AKT/mTOR-related overgrowth syndromes. This review describes the clinical findings, gene function and pathogenesis of these mosaic overgrowth syndromes, and presents existing and future treatment strategies to reduce or prevent associated complications of these disorders. © 2016 Wiley Periodicals, Inc.

Abstract LB-A20: Novel Dual Oncogenic Target Inhibitor against Allosteric Mitogen-Activated Protein Kinase (MEK1) and Phosphatidylinositol 3-Kinase (PI3K)

Abstract The Ras/MEK/ERK and PI3K/Akt/mTor pathways play a central role in the regulation of normal cell growth, division and differentiation. Dysregulation of these signaling pathways driven by oncogenic mutations/activation leading to elevated kinase activity has been demonstrated in many human cancers. Strong evidence suggests the existence of a feedback loop with crosstalk between these two signaling cascades leading to redundancy in survival pathways. Consequently, monotherapy targeting a single cascade may be insufficient to induce tumor cell death due to drug resistance mechanisms. Initial biological results are presented from a series of novel small molecule kinase inhibitors specifically designed to simultaneously target both MEK1 and PI3K. Structural analogs of the ATP-competitive PI3K inhibitor ZSTK474 and the ATP-noncompetitive class of MEK inhibitors PD0325901, respectively, were covalently combined to provide single compound dual inhibitors. Inhibitors showed potent MEK1 inhibition (0.015 < IC50 (nM) < 56.7) and PI3K inhibition (54 < IC50 (nM) < 341) in tumor cell culture inhibition assays. Cellular efficacy studies were accomplished and revealed several of the designed inhibitor analogs demonstrated near complete inhibition of MEK1 and PI3K kinase activity by western blot analysis in A549 lung adenocarcinoma and D54 glioma cell lines at concentrations as low as 5 μM. Inhibitors also produced dose-dependent decreases in cell viability in these cell lines similar to that displayed with the combined administration of equivalent doses of ZSTK474 and PD0325901. In vivo evaluation of selected compounds was undertaken to evaluate oral bioavailability and activity. In preliminary studies conducted in D54 glioma tumor bearing mice, a 95% and 67% inhibition of tumor ERK1/2 and Akt phosphorylation, respectively, was found at 2 h post-administration as determined by western blot analysis. This study reveals that dual targeted small molecules designed to inhibit MEK1/PI3K pathways were effective in target modulation in intact mouse tumor models. Overall, this study details a highly novel approach for combined MEK1/PI3K inhibition with first in vivo results. Citation Format: Brian D. Ross, Hao Hong, Hanxiao Wang, Charles A, Nino, Marcian E. Van Dort. Novel Dual Oncogenic Target Inhibitor against Allosteric Mitogen-Activated Protein Kinase (MEK1) and Phosphatidylinositol 3-Kinase (PI3K). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr LB-A20.

Oncogenes as Therapeutic Targets in Cancer: A Review

Carcinogenesis is a multi-step process which result in uncontrolled cell growth. Mutations in DNA that lead to cancer disrupt these orderly processes by disrupting the programming regulating the processes.. This results in uncontrolled cell division leading to carcinogenesis. Oncogenes are genes whose protein products stimulate or enhance the division and viability of cells. Oncogenes arise by activating mutation of their precursors, the proto-oncogenes. Proto-oncogenes are often directly involved in growth regulation of normal cells. Advances in molecular studies had led to the identification of many oncogenes in cancer formation. This will help in early detection of many cancers. The action of drugs on oncogenes will help in specific treatment of different types of cancers. An overview of the functions, properties and clinical importance of oncogenes is discussed in this review.

Tumour-Specific Uptake of Anti-Cancer Drugs: The Future is Here

A challenge of anti-cancer treatment is the specific delivery of the drugs in order to avoid deleterious effects on normal cells. In fact, anti-cancer drugs have potent effects also on normal cells due to the strong similarity of the mechanisms of growth regulation of normal cells if compared to their transformed counterparts. The recent developments in nanotechnology allow the old Ehrlich's dream to deliver anti-cancer drugs in tumour tissue through their encapsulation in drug delivery systems (DDS). In the present review we analyze the different reasons to encapsulate an anti-tumour drug in DDS including eventual damages induced by their extravasation or by eccipients used to their solubilisation, the rapid break-down of the drug in vivo and the specific bio-distribution of the drug in tumour tissues. The delivery strategies of anti-cancer drugs are based upon the particular structure of tumour neo-angiogenic vessels that allow the passive targeting or enhanced permeability and retention (EPR). In order to avoid the entrapping of DDS in reticulo-endothelial system the nanoparticles can be modified with the addition on their surface of inert polyetilenglicole (PEG) molecules that inhibit the opsonisation of DDS by macrophages. The addition of targeting moieties, antibodies or Fab fragments or small peptides and aptamers, on the surface of DDS can allow the active targeting of DDS to tumour cells. In conclusion, a new avenue in anti-cancer treatment has been disclosed with the use of DDS.

TGF‐β1 serum concentration as a complementary diagnostic biomarker of lung cancer: establishment of a cut‐point value

Lung cancer is a malignant disease with increasing mortality rates. Cytokines play a role in normal cell growth regulation and differentiation and are also implicated in malignant disease. Among these cytokines, Transforming Growth Factor β type 1 (TGF-β1) acts as a tumor promoter in malignant cells. Several clinical studies have found high levels of TGF-β1 in various cancer types. The aim of this study was to establish a TGF-β1 cut-off point as a complementary diagnostic tool in lung cancer detection. Therefore, 72 clinically well-characterized individuals were studied, 41 lung cancer patients and 31 healthy subjects. Serum TGF-β1 concentration was measured by an enzyme-linked immunosorbent assay (ELISA). We compared statistically the serum TGF-β1 concentration between both groups with analysis of variance, linear regression and receiver operating curve analysis. We observed that lung cancer patients produced higher TGF-β1 levels than healthy individuals (37,225±9,436 vs. 28,416±9,324 pg/ml, P<0.001). The cut-point diagnostic value was 30,500 pg/ml with 80.5% sensitivity, 64.5% specificity and odds ratio: 7.5, 95% CI: 2.6-21.8. We found significantly higher TGF-β1 levels in lung cancer patients than in healthy individuals. We propose the measurement of serum TGF-β1 levels as a complementary diagnostic test in lung cancer detection.

Involvement of Galectin-3 with Vascular Cell Adhesion Molecule-1 in Growth Regulation of Mouse BALB/3T3 Cells

beta-Galactose residues on N-glycans have been implicated to be involved in growth regulation of cells. In the present study we compared the galactosylation of cell surface N-glycans of mouse Balb/3T3 cells between 30 and 100% densities and found the beta-1,4-galactosylation of N-glycans increases predominantly in a 100-kDa protein band on lectin blot analysis in combination with digestions by diplococcal beta-galactosidase and N-glycanase. When cells at 100% density were treated with jack bean beta-galactosidase, the incorporation of 5-bromodeoxyuridine into the cells was stimulated in a dose-dependent manner, suggesting the involvement of the galactose residues in growth regulation of cells. A galactose-binding protein was isolated from the plasma membranes of cells at 100% density by affinity chromatography using an asialo-transferrin-Sepharose column and found to be galectin-3 as revealed by mass spectrometric analysis. The addition of recombinant galectin-3 into cells at 50% density inhibited the incorporation of 5-bromodeoxyuridine in a dose-dependent manner, but the inhibition was prevented with haptenic sugar. An immunocytochemical study showed that galectin-3 is present at the surface of cells at 100% density but not at 30% density where it locates inside the cells. Several glycoproteins bind to a galectin-3-immobilized column, a major of which was identified as vascular cell adhesion molecule (VCAM)-1. Immunocytochemical studies showed that some galectin-3 and VCAM-1 co-localize at the surface of cells at 100% density, indicating that the binding of galectin-3 secreted from cells to VCAM-1 is one of the pathways involved in the growth regulation of Balb/3T3 cells.

Alterations of c-Myc and c-erbB-2 genes in ovarian tumours

According to clinical and epidemiological studies, ovarian cancer ranks fifth in cancer deaths among women. The causes of ovarian cancer remain largely unknown but various factors may increase the risk of developing it, such as age, family history of cancer, childbearing status etc. This cancer results from a succession of genetic alterations involving oncogenes and tumour suppressor genes, which have a critical role in normal cell growth regulation. Mutations and/or overexpression of three oncogenes, c-erbB-2, c-Myc and K-ras, and of the tumour suppressor gene p53, have been frequently observed in a sporadic ovarian cancer. The aim of the present study was to analyse c-Myc and c-erbB-2 oncogene alterations, specifically amplification, as one of main mechanisms of their activation in ovarian cancers and to establish a possible association with the pathogenic process. DNA was isolated from 15 samples of malignant and 5 benign ovarian tumours, using proteinase K digestion, followed by phenol-chloroform isoamyl extraction and ethanol precipitation. C-Myc and c-erbB-2 amplification were detected by differential PCR. The level of gene copy increase was measured using the Scion image software. The amplification of both c-Myc and c-erbB-2 was detected in 26.7% of ovarian epithelial carcinoma specimens. Only one tumour specimen concomitantly showed increased gene copy number for both studied genes. Interestingly, besides amplification, gene deletion was also detected (26.7% for c-erbB-2). Most of the ovarian carcinomas with alterations in c-Myc and c-erbB-2 belonged to advanced FIGO stages. The amplification of c-Myc and c-erbB-2 oncogenes in ovarian epithelial carcinomas is most probably a late event in the pathogenesis conferring these tumours a more aggressive biological behaviour. Similarly, gene deletions point to genomic instability in epithelial carcinomas in higher clinical stages as the result of clonal evolution and selection.

Knockdown of MBP-1 in Human Foreskin Fibroblasts Induces p53-p21 Dependent Senescence

MBP-1 acts as a general transcriptional repressor. Overexpression of MBP-1 induces cell death in a number of cancer cells and regresses tumor growth. However, the function of endogenous MBP-1 in normal cell growth regulation remains unknown. To unravel the role of endogenous MBP-1, we knocked down MBP-1 expression in primary human foreskin fibroblasts (HFF) by RNA interference. Knockdown of MBP-1 in HFF (HFF-MBPsi-4) resulted in an induction of premature senescence, displayed flattened cell morphology, and increased senescence-associated beta-galactosidase activity. FACS analysis of HFF-MBPsi-4 revealed accumulation of a high number of cells in the G1-phase. A significant upregulation of cyclin D1 and reduction of cyclin A was detected in HFF-MBPsi-4 as compared to control HFF. Senescent fibroblasts exhibited enhanced expression of phosphorylated and acetylated p53, and cyclin-dependent kinase inhibitor, p21. Further analysis suggested that promyolocytic leukemia protein (PML) bodies are dramatically increased in HFF-MBPsi-4. Together, these results demonstrated that knockdown of endogenous MBP-1 is involved in cellular senescence of HFF through p53-p21 pathway.

MDM2 Regulates Dihydrofolate Reductase Activity through Monoubiquitination

MDM2 is a ubiquitin ligase that is best known for its essential function in the negative regulation of p53. In addition, MDM2 expression is associated with tumor progression in a number of common cancers, and in some cases, this has been shown to be independent of p53 status. MDM2 has been shown to promote the degradation of a number of other proteins involved in the regulation of normal cell growth and proliferation, including MDM4 and RB1. Here, we describe the identification of a novel substrate for the MDM2 ubiquitin ligase: dihydrofolate reductase (DHFR). MDM2 binds directly to DHFR and catalyses its monoubiquitination and not its polyubiquitination. In addition, MDM2 expression reduces DHFR activity in a p53-independent manner, but has no effect upon the steady-state level of expression of DHFR. We show that changes in MDM2 expression alter folate metabolism in cells as evidenced by MDM2-dependent alteration in the sensitivity of cells to the antifolate drug methotrexate. Furthermore, we show that the ability of MDM2 to inhibit DHFR activity depends upon an intact MDM2 RING finger. Our studies provide for the first time a link between MDM2, an oncogene with a critical ubiquitin ligase activity and a vital one-carbon donor pathway involved in epigenetic regulation, and DNA metabolism, which has wide ranging implications for both cell biology and tumor development.

The Development of Targeted Therapies for Hepatocellular Cancer

Present treatment options for hepatocellular cancer (HCC) are limited to those individuals with good liver function and early stage disease. Unfortunately this includes only a minority of patients, few of which are actually cured of their cancer. Over the last 15-20 years biotechnology has made a very significant impact on medical research, to the extent that we know very much more about the regulation of normal cell growth and death, as well as the mechanisms underlying its disruption in disease processes. This knowledge has and is being rapidly exploited by academic and pharmaceutical organisations, often in collaboration. The result is the development, testing and steady introduction of therapies that target specific abnormalities in cancer cells. Although the safety and effectiveness of the majority of these agents has yet to be established in cirrhotic patients with HCC, we are hopeful that we will shortly see an increase in effective treatment options available for clinical use this disease. This review focuses on aberrant cancer proteins and pathways relevant to HCC, as well as the novel therapies or strategies targeting them, that are currently in the development or testing stages.

A Mutant Type 2 Herpes Simplex Virus Deleted for the Protein Kinase Domain of the ICP10 Gene Is a Potent Oncolytic Virus

Replication-selective oncolytic herpes simplex virus (HSV) has shown considerable promise as an antitumor agent. Although the current oncolytic HSVs were exclusively constructed from HSV-1, HSV-2 has several unique features that could be exploited to convert the virus to an oncolytic agent. The N-terminus of the HSV-2 ICP10 gene product contains a well-defined serine/threonine protein kinase (PK) domain, which can activate the Ras/MEK/MAPK mitogenic pathway and thus facilitate efficient HSV-2 replication. Because the Ras signaling pathway is a key regulator of normal cell growth and malignant transformation, it is aberrantly activated in many human tumors. Here we report that a mutant HSV-2 (FusOn-H2), constructed by replacing the PK domain of ICP10 with the gene encoding the green fluorescent protein, can selectively replicate in and thus lyse tumor cells. Moreover, infection of FusOn-H2 led to syncytia formation in tumor cells, providing an additional tumor-destroying mechanism. A single moderate-dose injection of FusOn-H2 into established breast cancer xenografts completely eradicated the tumors in more than 80% of the animals, leading to their long-term survival. We conclude that this HSV-2 mutant is a safe and potent oncolytic agent useful for the treatment of malignant solid tumors such as breast cancer.

Nonclassical Action of Retinoic Acid on the Activation of the cAMP Response Element-binding Protein in Normal Human Bronchial Epithelial Cells

Vitamin A (retinol) is essential for normal regulation of cell growth and differentiation. We have shown that the retinol metabolite retinoic acid (RA) induces mucous cell differentiation of normal human tracheobronchial epithelial (NHTBE) cells. However, early biological effects of RA in the differentiation of bronchial epithelia are largely unknown. Here, we showed that RA rapidly activated cAMP response element-binding protein (CREB). However, RA did not use the conventional retinoic acid receptor (RAR)/retinoid X receptor (RXR) to activate CREB. RA activated CREB in NHTBE and H1734 cells in which RARs/RXR were silenced with small interfering RNA (siRNA) targeting RAR/RXR expression or deactivated by antagonist. Inhibition of protein kinase C (PKC) or extracellular regulated kinase (ERK1/2) blocked the RA-mediated activation of CREB. In addition, depletion of p90 ribosomal S6 kinase (RSK) via siRSK1/2 completely abolished the activation, suggesting that PKC, ERK, and RSK are required for the activation. Altogether, this study provides the first evidence that RA rapidly activates CREB transcription factor via PKC, ERK, and RSK in a retinoid receptor-independent manner in normal bronchial epithelial cells. This noncanonical RA signaling pathway may play an important role in mediating early biological effects in the mucociliary differentiation of bronchial epithelia.

Aberrant expression of insulin-like growth factor-2 (IGF-2) in Philadelphia chromosome negative chronic myeloproliferative disorders

Philadelphia chromosome negative chronic myeloproliferative disorders (Ph − CMPD) comprise haematopoietic stem cell disorders with currently unknown underlying molecular defect. Insulin-like growth factor 2 (IGF-2) is an imprinted gene that is known to be involved in the regulation of normal cell growth and that is overexpressed by a variety of tumors. The expression of IGF-2 in bone marrow cells is largely unknown. In order to elucidate gene expression level, protein expression pattern, and a potential role of IGF-2 in the pathogenesis of Ph − CMPD, we quantitatively analyzed the expression of the IGF-2 gene in bone marrow cells of 69 cases with Ph − CMPD and 31 control cases by applying real-time RT-PCR. IGF-2 gene expression in idiopathic myelofibrosis (IMF) was significantly increased by up to 11-fold as compared to the control group ( P<0.0001). IMF also expressed higher IGF-2 gene level as compared to essential thrombocythaemia (ET) and polycythaemia vera (PV) ( P<0.0001, P=0.005, respectively). Paranuclear IGF-2 protein could be demonstrated in IMF, ET, and PV exclusively in megakaryocytes and myeloid progenitor cells in contrast to undetectable IGF-2 protein in control cases. We conclude that overexpression of the IGF-2 gene is a pathogenic feature in IMF. In addition, an abundant translational and post-translational processing could explain the accumulation of IGF-2 protein detectable in all Ph − CMPD entities in contrast to non-neoplastic haematopoiesis. We conclude that IGF-2 represents a new molecular target for evaluation of underlying fundamental pathomechanisms in Ph − CMPD.