Gene expression profiles in cells transformed by overexpression of the IGF-I receptor

Naringenin promotes angiogenesis of ischemic myocardium after myocardial infarction through miR-223-3p/IGF1R axis

Introduction

Naringenin exerts a protective effect on myocardial ischemia and reperfusion. It has been reported that miR-223-3p is a potential target for the treatment of myocardial infarction (MI). In view of the unreported correlation between Naringenin and miR-223-3p, this study was designed to confirm that the ameliorative effects of Naringenin on MI is directly related to the regulation of miR-223-3p.

Methods

Through electrocardiogram detection, Masson pathological staining and immunohistochemistry of angiogenesis-related factors, alleviative effects of Naringenin on heart function, myocardial injury and angiogenesis in MI mice were observed individually. Hypoxic HUVECs were selected in the in vitro experimental model. The cell viability, angiogenesis and migration ability were analyzed to fathom out the pro-angiogenesis potential of Naringenin. The effect of Naringenin on miR-223-3p, as well as the downstream molecular mechanism was verified through bioinformatics analysis and rescue experiments.

Results

Naringenin improved heart functions of MI mice, reduced degree of myocardial fibrosis, stimulated expressions of angiogenic factors and down-regulated level of miR-223-3p in myocardial tissue. In in vitro experiments, Naringenin increased the viability of hypoxic HUVECs, as well as the abilities of tube formation and migration, and further inhibited the expression of miR-223-3p. In the rescue trial, miR-223-3p mimic reversed the therapeutic effect of Naringenin. Type 1 insulin-like growth factor receptor (IGF1R), as a downstream target gene of miR-223-3p, partially offset the cellular regulatory effects of miR-223-3p after overexpression of IGF1R.

Conclusions

Naringenin improves the angiogenesis of hypoxic HUVECs by regulating the miR-223-3p/IGF1R axis, and has the potential to promote myocardial angiogenesis in MI mice.

PDLIM2 is highly expressed in Breast Cancer tumour-associated macrophages and is required for M2 macrophage polarization

The PDZ-LIM domain-containing protein 2 (PDLIM2) regulates cell polarity and the protein stability of key transcription factors in epithelial and hemopoietic cells. We previously reported that PDLIM2 is more highly expressed in Triple Negative Breast Cancer (TNBC) than in other breast cancer types or normal breast tissue. In the course of the TNBC study, it was noted that PDLIM2 was highly expressed in the stroma of PDLIM2-expressing tumours. Here, we investigated the phenotype of these stromal cells and whether any infiltrating immune population was linked to PDLIM2 expression. We found that high PDLIM2 expression in breast tumours was associated with higher levels of infiltrating M2 macrophages, but was not associated with infiltrating T cell sub-populations. We then tested whether PDLIM2 contributes to macrophage differentiation or function by using cultures of bone marrow-derived macrophages from wildtype and Pdlim2 knockout mice. This demonstrated that PDLIM2 is required for naïve macrophage migration and for the full adoption of IL-4-induced M2 polarization, including expression of M2 phenotypic markers, cell adhesion and cell migration. TLR4-, TLR3- or IFNγ-induced M1 macrophage activity was less dependent on PDLIM2. Finally, analysis of publicly available breast cancer datasets showed that high PDLIM2 expression is associated with increased M2 macrophage infiltration. We conclude that PDLIM2 expression influences the tumour associated stroma and, in particular, M2 macrophage infiltration that may contribute to the progression of TNBC or other subsets of breast cancer.

High Expression of PDLIM2 Predicts a Poor Prognosis in Prostate Cancer and Is Correlated with Epithelial-Mesenchymal Transition and Immune Cell Infiltration

Purpose

To elucidate the clinical and prognostic role of PDZ and LIM domain protein (PDLIM) genes and the association to epithelial-mesenchymal transition (EMT) and immune cell infiltration in patients with prostate cancer (PRAD).

Methods

The data of RNA-seq, DNA methylation, and clinical features of PRAD patients were collected from The Cancer Genome Atlas (TCGA) database to define the prognostic value of PDLIM gene expression and the association with EMT and immune cell infiltration. A tissue microarray including 134 radical prostatectomy specimens was served as validation by immunohistochemistry (IHC) staining analysis.

Results

The mRNA levels of PDLIM1/2/3/4/6/7 were significantly downregulated, while PDLIM5 was upregulated in PRAD (P < 0.05). High expression of PDLIM2 mRNA suggests poor progression free interval in PRAD patients. DNA methylation of PDLIM2 was correlated with its mRNA expression level, and that the cg22973076 methylation site in PDLIM2 was associated with shorter PFI (P < 0.05) in PRAD. Single-sample gene-set enrichment and gene functional enrichment results showed that PDLIM2 was correlated with EMT and immune processes. Spearman's test showed a significant correlation with six reported EMT signatures and several EMT signature-related genes. Tumor microenvironment analysis revealed that the PDLIM2 mRNA expression was positively correlated with the immune score, stromal score, and various tumor infiltrating immune cells. Additionally, the results showed that patients in the high-PDLIM2 mRNA expression group may be more sensitive to immune checkpoint blockade therapy. Finally, IHC analysis further implicated the protein level of PDLIM2 was upregulated in PRAD and acts as a novel potential biomarker in predicting tumor progression.

Conclusion

Our study suggests that PDLIM family genes might be significantly correlated with oncogenesis and the progression of PRAD. PDLIM2 correlated with EMT and immune cell infiltration by acting as an oncogene in PRAD, which may serve as a potential prognostic biomarker for PRAD patients.

PDLIM2: Signaling pathways and functions in cancer suppression and host immunity

PDZ and LIM domains-containing proteins play pivotal functions in cell cytoskeleton organization, cell polarization and differentiation. As a key member of the family, PDLIM2 regulates stability and activity of transcription factors such as NF-κB, STATs and β-catenin, and thus exert it functions in inflammation, immunity, and cancer. PDLIM2 functions as a tumor suppressor in multiple tissues and it is often genetically mutated or epigenetically silenced in human cancers derived from lung, breast, ovarian and other histologies. However, in certain types of cancers, PDLIM2 may promote cancer cell proliferation and metastases. Therefore, PDLIM2 is added to a long list of genes that can function as tumor suppressor or oncogenic protein. During tumorigenesis induced by oncogenic viruses, PDLIM2 is a key target. Through promotion of NF-κB/RelA and STAT3 degradation, PDLIM2 enhances expression of proteins involved in antigen presentation and promotes T-cell activation while repressing multidrug resistance genes, thereby rendering mutated cells susceptible to immune surveillance and cytotoxicity mediated by immune cells and chemotherapeutic drugs. Intriguingly, PDLIM2 in alveolar macrophages (AMs) plays key roles in monitoring lung tumorigenesis, as its selective genetic deletion leads to constitutive activation of STAT3, driving monocyte differentiation to AMs with pro-tumorigenic polarization and activation. PDLIM2 has also been explored as a therapeutic target for cancer therapy. At the end of this review, we provide perspectives on this important molecule and discuss the future directions of both basic and translational studies.

miR‑589‑3p sponged by the lncRNA TINCR inhibits the proliferation, migration and invasion and promotes the apoptosis of breast cancer cells by suppressing the Akt pathway via IGF1R

The long non-coding (lnc)RNA named tissue differentiation inducing non-protein coding RNA (TINCR) is a tumor marker that has not been studied in breast cancer. The present study aimed to investigate the TINCR-targeting micro (mi)RNAs and the regulatory mechanisms of TINCR in breast cancer. Following prediction by TargetScan and confirmation by dual-luciferase reporter assay, TINCR was demonstrated to be a target gene for miR-589-3p. The expression of TINCR and miR-589-3p in breast cancer and adjacent tissues was detected by reverse transcription-quantitative (RT-q)PCR, and the correlation between TINCR and miR-589-3p expression was determined by using Spearman correlation analysis. The 5-years survival was analyzed in patients with breast cancer according to TINCR expression (high or low). The effects of TINCR and miR-589-3p on the proliferation, apoptosis, migratory and invasive abilities of some breast cancer cell lines were detected by MTT assay, flow cytometry, wound healing assay and Transwell assay. The target gene of miR-589-3p was predicted and verified by TargetScan and dual-luciferase reporter assay, and the mechanism of miR-589-3p involvement in breast cancer cells was explored by overexpression or downregulation of miR-589-3p in breast cancer cells. RT-qPCR and western blotting were used to determine the expression of the insulin-like growth factor 1 receptor (IGF1R)/AKT pathway-related genes. The results demonstrated that TINCR expression level was negatively correlated with miR-589-3p expression level in breast cancer tissues and that patients with high expression of TINCR presented with lower survival rates. In addition, TINCR overexpression in cancer cells inhibited miR-589-3p expression, and cell transfection with miR-589-3p mimic partially reversed the effect of TINCR overexpression on the promotion of cancer cell proliferation, migration and invasion, and on the inhibition of cancer cell apoptosis. Furthermore, IGF1R, which is a target gene of miR-589-3p, increased cancer cell proliferation, migration and invasion and inhibited cancer cell apoptosis; however, these effects were partially reversed by miR-589-3p mimic. Furthermore, the results demonstrated that miR-589-3p mimic could downregulate the protein expression of IGF1R and p-AKT. In addition, TINCR overexpression downregulated miR-589-3p expression level. miR-589-3p partially reversed the effects of TINCR overexpression on cancer cell proliferation, migration and invasion, and inhibited cancer cell apoptosis by inhibiting the IGF1R-Akt pathway. The results from the present study demonstrated that TINCR may sponge miR-589-3p in order to inhibit IGF1R-Akt pathway activation in breast cancer cells, promoting therefore cancer cell proliferation, migration and invasion.

Tumor suppressor p53 regulates insulin receptor (INSR) gene expression via direct binding to the INSR promoter

A significant volume of clinical and epidemiological data provides support to the concept that insulin and the insulin receptor (INSR) have an important role in breast cancer. Tumor suppressor p53 is the most frequently mutated molecule in human cancer. The present study was aimed at evaluating the hypothesis that p53 governs the expression and activation of the INSR gene in breast cancer cells. In addition, the study was designed to investigate the mechanism of action of p53 in the context of INSR gene regulation. The availability of MCF7 breast cancer-derived cell lines with specific disruption of either the insulin-like growth factor-1 receptor (IGF1R) or INSR allowed us to address the impact of the IGF1R and INSR pathways on p53 expression. Data indicate that the INSR gene constitutes a target for p53 action. Wild-type p53 stimulated INSR promoter activity in control cells while disruption of endogenous IGF1R or INSR led to inhibition of promoter activity by p53. Mutant p53 strongly stimulated INSR promoter. Furthermore, p53 directly binds to the INSR promoter in cells with a disrupted IGF1R. Combined, our results identified complex functional and physical interactions between p53 and the INSR pathway. The implications of the p53-INSR interplay in breast cancer needs to be further investigated.

Genetic Diversity and Signatures of Selection in a Native Italian Horse Breed Based on SNP Data

Simple Summary

The Bardigiano horse is a native Italian breed bred for living in rural areas, traditionally used in agriculture. The breed counts about 3000 horses, and it is nowadays mainly used for recreational purposes. The relatively small size and the closed status of the breed raise the issue of monitoring genetic diversity. We therefore characterized the breed’s genetic diversity based on molecular data. We showed a critical reduction of genetic variability mainly driven by past bottlenecks. We also highlighted homozygous genomic regions that might be the outcome of directional selection in recent years, in line with the conversion of Bardigiano horses from agricultural to riding purposes.

Abstract

Horses are nowadays mainly used for sport and leisure activities, and several local breeds, traditionally used in agriculture, have been exposed to a dramatic loss in population size and genetic diversity. The loss of genetic diversity negatively impacts individual fitness and reduces the potential long-term survivability of a breed. Recent advances in molecular biology and bioinformatics have allowed researchers to explore biodiversity one step further. This study aimed to evaluate the loss of genetic variability and identify genomic regions under selection pressure in the Bardigiano breed based on GGP Equine70k SNP data. The effective population size based on Linkage Disequilibrium (N_e) was equal to 39 horses, and it showed a decline over time. The average inbreeding based on runs of homozygosity (ROH) was equal to 0.17 (SD = 0.03). The majority of the ROH were relatively short (91% were ≤2 Mbp long), highlighting the occurrence of older inbreeding, rather than a more recent occurrence. A total of eight ROH islands, shared among more than 70% of the Bardigiano horses, were found. Four of them mapped to known quantitative trait loci related to morphological traits (e.g., body size and coat color) and disease susceptibility. This study provided the first genome-wide scan of genetic diversity and selection signatures in an Italian native horse breed.

PDLIM2 Is a Marker of Adhesion and β-Catenin Activity in Triple-Negative Breast Cancer

The PDLIM2 protein regulates stability of transcription factors including NF-κB and STATs in epithelial and hemopoietic cells. PDLIM2 is strongly expressed in certain cancer cell lines that exhibit an epithelial-to-mesenchymal phenotype, and its suppression is sufficient to reverse this phenotype. PDLIM2 supports the epithelial polarity of nontransformed breast cells, suggesting distinct roles in tumor suppression and oncogenesis. To better understand its overall function, we investigated PDLIM2 expression and activity in breast cancer. PDLIM2 protein was present in 60% of tumors diagnosed as triple-negative breast cancer (TNBC), and only 20% of other breast cancer subtypes. High PDLIM2 expression in TNBC was positively correlated with adhesion signaling and β-catenin activity. Interestingly, PDLIM2 was restricted to the cytoplasm/membrane of TNBC cells and excluded from the nucleus. In breast cell lines, PDLIM2 retention in the cytoplasm was controlled by cell adhesion, and translocation to the nucleus was stimulated by insulin-like growth factor-1 or TGFβ. Cytoplasmic PDLIM2 was associated with active β-catenin and ectopic expression of PDLIM2 was sufficient to increase β-catenin levels and its transcriptional activity in reporter assays. Suppression of PDLIM2 inhibited tumor growth in vivo, whereas overexpression of PDLIM2 disrupted growth in 3D cultures. These results suggest that PDLIM2 may serve as a predictive biomarker for a large subset of TNBC whose phenotype depends on adhesion-regulated β-catenin activity and which may be amenable to therapies that target these pathways. SIGNIFICANCE: This study shows that PDLIM2 expression defines a subset of triple-negative breast cancer that may benefit from targeting the β-catenin and adhesion signaling pathways. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/79/10/2619/F1.large.jpg.

A genome-wide association study for body weight in Japanese Thoroughbred racehorses clarifies candidate regions on chromosomes 3, 9, 15, and 18

Body weight is an important trait to confirm growth and development in humans and animals. In Thoroughbred racehorses, it is measured in the postnatal, training, and racing periods to evaluate growth and training degrees. The body weight of mature Thoroughbred racehorses generally ranges from 400 to 600 kg, and this broad range is likely influenced by environmental and genetic factors. Therefore, a genome-wide association study (GWAS) using the Equine SNP70 BeadChip was performed to identify the genomic regions associated with body weight in Japanese Thoroughbred racehorses using 851 individuals. The average body weight of these horses was 473.9 kg (standard deviation: 28.0) at the age of 3, and GWAS identified statistically significant SNPs on chromosomes 3 (BIEC2_808466, P=2.32E-14), 9 (BIEC2_1105503, P=1.03E-7), 15 (BIEC2_322669, P=9.50E-6), and 18 (BIEC2_417274, P=1.44E-14), which were associated with body weight as a quantitative trait. The genomic regions on chromosomes 3, 9, 15, and 18 included ligand-dependent nuclear receptor compressor-like protein (LCORL), zinc finger and AT hook domain containing (ZFAT), tribbles pseudokinase 2 (TRIB2), and myostatin (MSTN), respectively, as candidate genes. LCORL and ZFAT are associated with withers height in horses, whereas MSTN affects muscle mass. Thus, the genomic regions identified in this study seem to affect the body weight of Thoroughbred racehorses. Although this information is useful for breeding and growth management of the horses, the production of genetically modified animals and gene doping (abuse/misuse of gene therapy) should be prohibited to maintain horse racing integrity.

Role of LASP-1, a novel SOX9 transcriptional target, in the progression of lung cancer

Lung cancer accounts for most cancer-related deaths worldwide. However, the underlying mechanism by which it mediates the progression of lung cancer remains unclear. Expression of LASP-1 (LIM and SH3 protein 1) was evaluated in lung cancer tissues and tumor-adjacent normal tissues using immunohistochemistry and western blotting. Functional studies have shown that siRNA-mediated silencing of LASP-1 in human lung cancer cells and reduced cell proliferation, migration, and invasion. Flow cytometry and immunofluorescence staining also revealed that rate of cell apoptosis was increased after knockdown of expression of LASP-1, thereby suggesting that LASP-1 may function as an oncogene during lung cancer progression. SOX9 is an important transcription factor, which is involved in the development of several types of human cancer. Further analysis has showed the presence of a consensus-binding site of SOX9 in the promoter region of LASP-1. Mechanistic investigations showed that LASP-1 was transcriptionally activated by SOX9. Through luciferase reporter and ChIP assays, we demonstrated that LASP-1 was a direct target gene of sex determining region Y-box 9 (SOX9). Knockdown of SOX9 expression by RNA interference reduces cell proliferation and induces apoptosis of lung cancer cells, which was consistent with the results obtained from silencing the expression of LASP-1 in NCI‑H1650 cells. Together, these findings indicated that LASP-1, as a downstream target of SOX9, may act as a novel biomarker for lung cancer and plays an important role in cell proliferation, migration, and invasion.

Suppression of LIM and SH3 Domain Protein 1 (LASP1) Negatively Regulated by Androgen Receptor Delays Castration Resistant Prostate Cancer Progression

BACKGROUND

LIM and SH3 domain protein 1 (LASP1) has been implicated in several human malignancies and has been shown to predict PSA recurrence in prostate cancer. However, the anti-tumor effect of LASP1 knockdown and the association between LASP1 and the androgen receptor (AR) remains unclear. The aim of this study is to clarify the significance of LASP1 as a target for prostate cancer, and to test the effect of silencing LASP1 in vivo using antisense oligonucleotides (ASO).

METHODS

A tissue microarray (TMA) was performed to characterize the differences in LASP1 expression in prostate cancer treated after hormone deprivation therapy. Flow cytometry was used to analyze cell cycle. We designed LASP1 ASO for knockdown of LASP1 in vivo studies.

RESULTS

The expression of LASP1 in TMA was increased after androgen ablation and persisted in castration resistant prostate cancer (CRPC). Also in TMA, compared with LNCaP cell, LASP1 expression is elevated in CRPC cell lines (C4-2 and VehA cells). Interestingly, suppression of AR elevated LASP1 expression conversely, AR activation decreased LASP1 expression. Silencing of LASP1 reduced cell growth through G1 arrest which was accompanied by a decrease of cyclin D1. Forced overexpression of LASP1 promoted cell cycle and induced cell growth which was accompanied by an increase of cyclin D1. Systemic administration of LASP1 ASO with athymic mice significantly inhibited tumor growth in CRPC xenografts.

CONCLUSIONS

These results indicate that LASP1 is negatively regulated by AR at the transcriptional level and promotes tumor growth through induction of cell cycle, ultimately suggesting that LASP1 may be a potential target in prostate cancer treatment. Prostate 77:309-320, 2017. © 2016 Wiley Periodicals, Inc.

Global Proteome and Phospho-proteome Analysis of Merlin-deficient Meningioma and Schwannoma Identifies PDLIM2 as a Novel Therapeutic Target

Loss or mutation of the tumour suppressor Merlin predisposes individuals to develop multiple nervous system tumours, including schwannomas and meningiomas, sporadically or as part of the autosomal dominant inherited condition Neurofibromatosis 2 (NF2). These tumours display largely low grade features but their presence can lead to significant morbidity. Surgery and radiotherapy remain the only treatment options despite years of research, therefore an effective therapeutic is required.

Unbiased omics studies have become pivotal in the identification of differentially expressed genes and proteins that may act as drug targets or biomarkers. Here we analysed the proteome and phospho-proteome of these genetically defined tumours using primary human tumour cells to identify upregulated/activated proteins and/or pathways. We identified over 2000 proteins in comparative experiments between Merlin-deficient schwannoma and meningioma compared to human Schwann and meningeal cells respectively. Using functional enrichment analysis we highlighted several dysregulated pathways and Gene Ontology terms. We identified several proteins and phospho-proteins that are more highly expressed in tumours compared to controls. Among proteins jointly dysregulated in both tumours we focused in particular on PDZ and LIM domain protein 2 (PDLIM2) and validated its overexpression in several tumour samples, while not detecting it in normal cells. We showed that shRNA mediated knockdown of PDLIM2 in both primary meningioma and schwannoma leads to significant reductions in cellular proliferation.

To our knowledge, this is the first comprehensive assessment of the NF2-related meningioma and schwannoma proteome and phospho-proteome. Taken together, our data highlight several commonly deregulated factors, and indicate that PDLIM2 may represent a novel, common target for meningioma and schwannoma.

•

Proteome and phosphoproteome of Merlin-deficient schwannomas and meningiomas were analysed.

•

Comparative studies highlighted several pathways relevant for therapeutic intervention.

•

PDLIM2 was identified as a novel, commonly upregulated protein in both tumours.

•

PDLIM2 knockdown led to a significant reduction in proliferation in both cell types.

Loss or mutation of the protein Merlin causes a genetic condition known as Neurofibromatosis 2 (NF2) characterised by the growth of schwannomas and meningiomas.

We analysed several of these tumour samples and identified over 2000 proteins in comparative experiments between Merlin-deficient schwannoma and meningioma compared to normal controls. We identified PDZ and LIM domain protein 2 (PDLIM2) as overexpressed in both tumour types and further showed that knockdown of PDLIM2 leads to significant reductions in cellular proliferation.

Taken together, our data highlight several deregulated signalling pathways, and indicate that PDLIM2 may represent a novel, common target for meningioma and schwannoma.

PDLIM2 suppression efficiently reduces tumor growth and invasiveness of human castration-resistant prostate cancer-like cells

BACKGROUND

Although PDLIM2 gene may have a context-dependent role in various human malignancies and can be a potential therapeutic target, only a limited number of in vitro studies addressed the molecular functions of PDLIM2 in prostate cancer. Here, we aimed to explore the role of PDLIM2 and the effect of the PDLIM2 gene suppression on oncogenic phenotypes of human castration-resistant prostate cancer (CRPC)-like cells.

METHODS

We used human CRPC-like cell lines (PC3, DU145, and C4-2B) for our experiments. Transcription levels of PDLIM2 and relevant genes were measured by real time-PCR and protein expression was analyzed by western blot. Cell viability, proliferation, clonogenic growth, and tumor sphere formation were examined after a specific inhibition of PDLIM2 using RNA interference. Flow cytometry was used to examine apoptotic cell death and cell cycle disturbances. Wound healing and transwell migration assays were performed to investigate the invasion capabilities of CRPC-like cells. Additionally, key oncogenic signaling pathways were examined using western blot. Lastly, we evaluated the in vivo efficacy of PDLIM2 suppression on tumor growth of human CRPC xenografts in mice.

RESULTS

We observed a significant enhancement of PDLIM2 expression in human CRPC-like cell lines, while a specific inhibition of PDLIM2 reduced cell viability and proliferation due to apoptotic cell death. Conversely, PDLIM2 overexpression significantly reduced cell proliferation compared to the negative control in androgen-sensitive LNCaP cells. Moreover, PDLIM2 suppression led to a decrease of clonogenic growth and tumor sphere formation in three-dimensional cultures with the G2/M cell cycle arrest in human CRPC-like cells. PDLIM2 inhibition also attenuated cellular migration and invasion capabilities of human CRPC-like cells, and reduced the expression of mesenchymal marker. Among several oncogenic signaling pathways, only the MAPK/ERK signaling cascade was decreased by PDLIM2 inhibition and reciprocally, ERK inhibition down-regulated PDLIM2 expression. Importantly, PDLIM2 inhibition remarkably compromised tumor growth in a human CRPC xenograft model.

CONCLUSION

In summary, the suppression of PDLIM2 significantly reduced such oncogenic phenotypes as proliferation, clonogenicity, invasiveness, and tumor cell growth in human CRPC-like cells both in vitro and in vivo, indicating that PDLIM2 may be considered a novel therapeutic target gene for treating human CRPC.

Inhibition of IGF-1R diminishes transcriptional activity of the androgen receptor and its constitutively active, C-terminally truncated counterparts Q640X and AR-V7

PURPOSE

Failure of endocrine treatment in castration-resistant prostate cancer (CRPC) is often associated with the emergence of C-terminally truncated androgen receptor variants that function as constitutively active transcription factors (i.e., AR∆LBD). The mechanisms involved in the regulation of AR∆LBD signaling are largely unknown. Since the IGF-1 pathway was repeatedly shown to affect AR function, we studied whether an inhibition of IGF-1R could also affect AR∆LBD signaling.

METHODS

Regulation of androgen receptor (AR) and AR∆LBD signaling was analyzed by reporter gene assays, immunoblotting, ELISA and quantitative RT-PCR.

RESULTS

Inhibition of IGF-1R with the small-molecule inhibitor NVP-AEW541 reduced the transcriptional activity of the AR and its truncated counterparts Q640X and AR-V7. As shown in Q640X, the inhibition of transcriptional activity was paralleled by a decreased receptor phosphorylation.

CONCLUSIONS

Inhibition of IGF-1R leads to a down-regulation of AR∆LBD signaling and provides a rationale for CRPC therapies targeting growth factor receptors.

IGF axis and other factors in HPV-related and HPV-unrelated carcinogenesis (review)

The insulin-like growth factor (IGF) axis promotes the growth of cells, tissues and organs. IGF-1 is mainly produced in the liver but is also secreted from local tissues. In the circulation, IGF-1 is bound to insulin-like binding proteins (IGFBPs), and when released it activates the insulin-like growth factor receptor (IGF-1R). The signal is further transmitted by intracellular signaling pathways leading to gene expression that regulates, among others, cell proliferation and survival. This review presents the IGF axis in the context of cell transformation and cancer development. Aspects involving IGF-1 deficiency and protection from cancer are also briefly described. Furthermore, human papillomaviruses (HPVs) interplaying with IGF axis components in cervical cancer development are described. These small dsDNA viruses are divided into low-risk and high-risk HPVs with regard to the potency of their oncogenic actions; they mainly infect epithelial or mucosal cells. Special attention is drawn to expression of two major HPV oncogenes (E6 and E7) initiating and maintaining cervical carcinogenesis, which is a multistep and multifactorial process; therefore, involvement of additional factors such as mitochondrial DNA changes, sex hormones, retinoic and folic acids are also discussed. Finally, IGF axis components and HPV oncogenes as targets in anticancer treatment are presented which include IGF-1R downregulation, RNA interference and anti-HPV therapeutic vaccines. The review concludes that despite an enormous advancement in research on IGF and HPV-related cancers, more molecular studies and clinical trials are needed before commercialized therapies are widely available for oncology patients.

Essential function for PDLIM2 in cell polarization in three-dimensional cultures by feedback regulation of the β1-integrin-RhoA signaling axis

PDLIM2 is a cytoskeletal and nuclear PDZ-LIM domain protein that regulates the stability of Nuclear Factor kappa-B (NFκB) and other transcription factors, and is required for polarized cell migration. PDLIM2 expression is suppressed by methylation in different cancers, but is strongly expressed in invasive breast cancer cells that have undergone an Epithelial Mesenchymal Transition (EMT). PDLIM2 is also expressed in non-transformed breast myoepithelial MCF10A cells and here we asked whether it is important for maintaining the polarized, epithelial phenotype of these cells. Suppression of PDLIM2 in MCF10A cells was sufficient to disrupt cell polarization and acini formation with increased proliferation and reduced apoptosis in the luminal space compared to control acini with hollow lumina. Spheroids with suppressed PDLIM2 exhibited increased expression of cell-cell and cell-matrix adhesion proteins including beta 1 (β1) integrin. Interestingly, levels of the Insulin-like growth factor 1 receptor (IGF-1 R) and Receptor of activated protein kinase C 1 (RACK1), which scaffolds IGF-1R to β1 integrin, were also increased, indicating a transformed phenotype. Focal Adhesion Kinase (FAK) and cofilin phosphorylation, and RhoA Guanosine Triphosphatase (GTPase) activity were all enhanced in these spheroids compared to control acini. Importantly, inhibition of either FAK or Rho Kinase (ROCK) was sufficient to rescue the polarity defect. We conclude that PDLIM2 expression is essential for feedback regulation of the β1-integrin-RhoA signalling axis and integration of cellular microenvironment signals with gene expression to control the polarity of breast epithelial acini structures. This is a mechanism by which PDLIM2 could mediate tumour suppression in breast epithelium.

PDLIM2 regulates transcription factor activity in epithelial-to-mesenchymal transition via the COP9 signalosome

PDLIM2 integrates cytoskeletal signaling with gene expression to enable reversible differentiation of epithelial cancer cells. PDLIM2 associates with the COP9 signalosome and controls its nuclear translocation and the stability of key transcription factors necessary for either a mesenchymal or an epithelial phenotype.

Epithelial cell differentiation and polarized migration associated with epithelial-to-mesenchymal transition (EMT) in cancer requires integration of gene expression with cytoskeletal dynamics. Here we show that the PDZ-LIM domain protein PDLIM2 (Mystique/SLIM), a known cytoskeletal protein and promoter of nuclear nuclear factor κB (NFκB) and signal transducer and activator of transcription (STAT) degradation, regulates transcription factor activity and gene expression through the COP9 signalosome (CSN). Although repressed in certain cancers, PDLIM2 is highly expressed in invasive cancer cells. Here we show that PDLIM2 suppression causes loss of directional migration, inability to polarize the cytoskeleton, and reversal of the EMT phenotype. This is accompanied by altered activity of several transcription factor families, including β-catenin, Ap-1, NFκB, interferon regulatory factors, STATs, JUN, and p53. We also show that PDLIM2 associates with CSN5, and cells with suppressed PDLIM2 exhibit reduced nuclear accumulation and deneddylation activity of the CSN toward the cullin 1 and cullin 3 subunits of cullin-RING ubiquitin ligases. Thus PDLIM2 integrates cytoskeleton signaling with gene expression in epithelial differentiation by controlling the stability of key transcription factors and CSN activity.

Lycopene modulates growth and survival associated genes in prostate cancer

Lycopene is a fat soluble red-orange carotenoid pigment present in tomato that reduces the risk for prostate cancer, a common malignancy among men. However, the mechanism by which lycopene attenuates prostate cancer is not fully defined. In this study we examined the effect of lycopene on proliferation, survival, and biomarker gene expression in prostate cancer (PC-3) cells in culture. WST-1 assay showed that lycopene induces a biphasic effect on PC-3 cells with a modest increase in proliferation at 1-5 μM, no change at 10-25 μM and a decrease at 50-100 μM doses in culture. Interestingly, combination treatment with lycopene induced anti-proliferative effect of Temozolomide on PC-3 cells. Lycopene also augmented the anti-proliferative effect of peroxisome proliferator-activated receptor gamma (PPARγ) agonists, but not Doxorubicin or Taxol, in prostate cancer. Flow cytometry analyses showed that lycopene, in combination with chemotherapeutic agents and PPARγ agonists, induced modest cell cycle arrest with significant increase in cell death by apoptosis and necrosis on prostate cancer. Gene array and quantitative reverse transcription polymerase chain reaction analyses showed that lycopene alters the expression of growth and apoptosis associated biomarkers in PC-3 cells. These findings highlight that lycopene attenuates prostate cancer by modulating the expression of growth and survival associated genes.

Role of hepatitis B virus X protein in regulating LIM and SH3 protein 1 (LASP-1) expression to mediate proliferation and migration of hepatoma cells

BACKGROUND

Hepatitis B virus X protein (HBx) has been shown to be responsible for the development of hepatocellular carcinoma (HCC) caused by Hepatitis B virus infection. However, its potential effect on the progression of hepatocellular carcinoma remains yet unclear. LIM and SH3 protein 1 (LASP-1), a focal adhesion protein, is expressed in an up-regulation manner in the HCC tissues. LASP-1 plays an important role in the regulation of proliferation and migration of HCC. In this study, we investigated the effect of LASP-1 involved in HBx-related tumor progression.

METHODS

LASP-1 levels in the HBx stable transfected HepG2 and Huh-7 cells were detected by RT-PCR and western blot analysis. The cellular localization of LASP-1 was assessed by immunofluorescence analysis. The activity of phosphatidylinositol 3-kinase (PI3-K) pathway was demonstrated by western blot assay. The HBx-expressing cells were transfected with specific small interference RNA (siRNA) against LASP-1. The proliferation and migration ability of cells were evaluated by cell viability assay and plate clone formation assay. The migration ability of cells was detected by transwell assay and wound healing assay.

RESULTS

RT-PCR and western blot analysis indicated the expression of LASP-1 was increased in the stable HBx-expressing cells compared with the control cells. Immunofluorescence study revealed that the distributions of LASP-1 in HepG2-HBX cells were mainly in pseudopods and the cytoplasm while they were mainly localized in the cytoplasm of HepG2-Mock cells. The cellular localizations of LASP-1 in Huh-7-HBX cells were in the perinuclear fractions while they were mainly localized in the cytoplasm of Huh-7-Mock cells. The upregulation of LASP-1 was inhibited after treatment with LY294002, PI3-K pathway inhibitor. Overexpression of LASP-1 in the stable HBx-expressing cells enhanced the proliferation and migration ability of hepatocellular cells. siRNA-mediated LASP-1 knowdown in the stable HBx-expressing cells significantly suppressed hepatocellular cells proliferation and migration.

CONCLUSIONS

These results demonstrated that HBx could upregulate LASP-1 through PI3-K pathway to promote the proliferation and migration of hepatoma cells.

Four loci explain 83% of size variation in the horse

Horse body size varies greatly due to intense selection within each breed. American Miniatures are less than one meter tall at the withers while Shires and Percherons can exceed two meters. The genetic basis for this variation is not known. We hypothesize that the breed population structure of the horse should simplify efforts to identify genes controlling size. In support of this, here we show with genome-wide association scans (GWAS) that genetic variation at just four loci can explain the great majority of horse size variation. Unlike humans, which are naturally reproducing and possess many genetic variants with weak effects on size, we show that horses, like other domestic mammals, carry just a small number of size loci with alleles of large effect. Furthermore, three of our horse size loci contain the LCORL, HMGA2 and ZFAT genes that have previously been found to control human height. The LCORL/NCAPG locus is also implicated in cattle growth and HMGA2 is associated with dog size. Extreme size diversification is a hallmark of domestication. Our results in the horse, complemented by the prior work in cattle and dog, serve to pinpoint those very few genes that have played major roles in the rapid evolution of size during domestication.

Minireview: IGF, Insulin, and Cancer

In recent years, the influence of the IGF system and insulin on cancer growth has been widely studied. Observational human studies have reported increased cancer mortality in those with obesity and type 2 diabetes, which may be attributable to hyperinsulinemia, elevated IGF-I, or potentially both factors. Conversely, those with low insulin, IGF-I and IGF-II levels appear to be relatively protected from cancer development. Initial attention focused on the role of IGF-I in tumor development. The results of these investigations allowed for the development of therapies targeting the IGF-I receptor signaling pathway. However, after in vitro and in vivo studies demonstrating that insulin may also play a significant and independent role in tumorigenesis, insulin is now receiving more attention in this regard. Some studies suggest that targeting insulin receptor signaling may be an important alternative or adjunct to targeting IGF-I receptor signaling. In this minireview, we discuss some of the recent in vitro, animal, and clinical studies that have elaborated our understanding of the influence of IGF and insulin on tumorigenesis. These studies have shed more light on the interaction between insulin and IGF signaling in cancer cells. They have made possible the development of novel targeted therapies and highlighted some of the potential future directions for research and therapeutics.

Regulation of receptor for activated C kinase 1 protein by the von Hippel-Lindau tumor suppressor in IGF-I-induced renal carcinoma cell invasiveness

von Hippel-Lindau (VHL) tumor suppressor loss is associated with renal cell carcinoma (RCC) pathogenesis. Meanwhile, aberrant activation of the insulin-like growth factor-I (IGF-I) signaling has been implicated in the development of highly invasive metastatic RCC. However, the link between VHL inactivation and RCC invasiveness is still unexplored. Here, we show that the receptor for activated C kinase 1 (RACK1) is a novel pVHL-interacting protein. pVHL competes with IGF-I receptor (IGF-IR) for binding to RACK1 thus potentially modulating the downstream IGF-I signal pathway. Upon IGF-I stimulation, pVHL-deficient RCC cells exhibit increased RACK1/IGF-IR binding and increased IGF-IR tyrosine kinase activity. pVHL-deficient RCC cells also demonstrate elevated PI3K/Akt signaling and matrix metalloproteinase-2 activity that culminates in enhanced cellular invasiveness, which can be partially suppressed by RACK1 small interfering RNA. Domain mapping analysis showed that the pVHL α-domain and the RACK1 WD 6-7 domains are critical for the interaction. Additionally, the RACK1 expression level is not regulated by pVHL expression status, suggesting that pVHL modifies RACK1 functions independent of the VHL/elongin E3 ubiquitin ligase complex. Our data indicate that RACK1 serves as a direct mediator between loss of pVHL function and enhanced IGF-IR signaling pathway in RCC.

Ribosomal 18 S RNA processing by the IGF-I-responsive WDR3 protein is integrated with p53 function in cancer cell proliferation

Insulin-like growth factor-I (IGF-I) signaling is strongly associated with cell growth and regulates the rate of synthesis of the rRNA precursor, the first and the key stage of ribosome biogenesis. In a screen for mediators of IGF-I signaling in cancer, we recently identified several ribosome-related proteins, including NEP1 (nucleolar essential protein 1) and WDR3 (WD repeat 3), whose homologues in yeast function in ribosome processing. The WDR3 gene and its locus on chromosome 1p12-13 have previously been linked with malignancy. Here we show that IGF-I induces expression of WDR3 in transformed cells. WDR3 depletion causes defects in ribosome biogenesis by affecting 18 S rRNA processing and also causes a transient down-regulation of precursor rRNA levels with moderate repression of RNA polymerase I activity. Suppression of WDR3 in cells expressing functional p53 reduced proliferation and arrested cells in the G(1) phase of the cell cycle. This was associated with activation of p53 and sequestration of MDM2 by ribosomal protein L11. Cells lacking functional p53 did not undergo cell cycle arrest upon suppression of WDR3. Overall, the data indicate that WDR3 has an essential function in 40 S ribosomal subunit synthesis and in ribosomal stress signaling to p53-mediated regulation of cell cycle progression in cancer cells.

Heme-binding protein HRG-1 is induced by insulin-like growth factor I and associates with the vacuolar H+-ATPase to control endosomal pH and receptor trafficking

Endocytosis and trafficking of receptors and nutrient transporters are dependent on an acidic intra-endosomal pH that is maintained by the vacuolar H(+)-ATPase (V-ATPase) proton pump. V-ATPase activity has also been associated with cancer invasiveness. Here, we report on a new V-ATPase-associated protein, which we identified in insulin-like growth factor I (IGF-I) receptor-transformed cells, and which was separately identified in Caenorhabditis elegans as HRG-1, a member of a family of heme-regulated genes. We found that HRG-1 is present in endosomes but not in lysosomes, and it is trafficked to the plasma membrane upon nutrient withdrawal in mammalian cells. Suppression of HRG-1 with small interfering RNA causes impaired endocytosis of transferrin receptor, decreased cell motility, and decreased viability of HeLa cells. HRG-1 interacts with the c subunit of the V-ATPase and enhances V-ATPase activity in isolated yeast vacuoles. Endosomal acidity and V-ATPase assembly are decreased in cells with suppressed HRG-1, whereas transferrin receptor endocytosis is enhanced in cells that overexpress HRG-1. Cellular uptake of a fluorescent heme analogue is enhanced by HRG-1 in a V-ATPase-dependent manner. Our findings indicate that HRG-1 regulates V-ATPase activity, which is essential for endosomal acidification, heme binding, and receptor trafficking in mammalian cells. Thus, HRG-1 may facilitate tumor growth and cancer progression.

Proteomic identification of LASP-1 down-regulation after RNAi urokinase silencing in human hepatocellular carcinoma cells

In human hepatocellular carcinoma (HCC), the high expression of urokinase-type plasminogen activator (uPA) is an unfavorable prognostic factor and a therapeutic target. To identify the downstream effects of uPA silencing by RNA interference, we studied proteome modifications of uPA-inhibited SKHep1C3 cells, an HCC-derived cell line. The study with two-dimensional difference gel electrophoresis and matrix-assisted laser desorption/ionization-time of flight-mass spectrometry showed Lim and SH3 protein 1 (LASP-1), cytokeratin 1 (CK-1), cytokeratin 10 (CK-10), and heterogeneous nuclear ribonucleoprotein H1 down-modulation after uPA inhibition. LASP-1, CK-1, and CK-10 are involved in cytoskeleton dynamics as heterogeneous nuclear ribonucleoprotein H1 takes part in the mRNA processing and stability. We first confirmed the proteomic data by Western blot and immunoflorescence and then explored the link between uPA and LASP-1. The ectopic expression of uPA and LASP-1 supported the proteomic results and showed that uPA up-regulation increased LASP-1 expression and that both were implicated in SKHep1C3 motility. siRNA LASP-1 inhibition showed that LASP-1 was involved in actin microfilaments organization of SKHep1C3 cells. The disruption of the actin microfilaments after LASP-1 depletion increased uPA secretion and SKHep1C3 motility. Our results would suggest the hypothesis that uPA and LASP-1 expression may be coordinated in HCC-derived cells. In summary, the proteomic identification of a set of uPA downstream proteins provides new insight into the function of uPA in HCC cells.

The LIM and SH3 domain protein family: structural proteins or signal transducers or both?

LIM and SH3 Protein 1 (LASP-1) was initially identified from a cDNA library of metastatic axillary lymph nodes (MLN) more than a decade ago. It was found to be overexpressed in human breast and ovarian cancer and became the first member of a newly defined LIM-protein subfamily of the nebulin group characterized by the combined presence of LIM and SH3 domains. LASP2, a novel LASP1-related gene was first identified and characterized in silico. Subsequently it proved to be a splice variant of the Nebulin gene and therefore was also termed LIM/nebulette. LASP-1 and -2 are highly conserved in their LIM, nebulin-like and SH3 domains but differ significantly at their linker regions. Both proteins are ubiquitously expressed and involved in cytoskeletal architecture, especially in the organization of focal adhesions. Here we present the first systematic review to summarize all relevant data concerning their domain organization, expression profiles, regulating factors and function. We compile evidence that both, LASP-1 and LASP-2, are important during early embryo- and fetogenesis and are highly expressed in the central nervous system of the adult. However, only LASP-1 seems to participate significantly in neuronal differentiation and plays an important functional role in migration and proliferation of certain cancer cells while the role of LASP-2 is more structural. The increased expression of LASP-1 in breast tumours correlates with high rates of nodal-metastasis and refers to a possible relevance as a prognostic marker.

Quantitative proteomics analysis of the effects of ionizing radiation in wild type and p53 K317R knock-in mouse thymocytes

The tumor suppressor protein p53 is a sequence-specific transcription factor that has crucial roles in apoptosis, cell cycle arrest, cellular senescence, and DNA repair. Following exposure to a variety of stresses, p53 becomes post-translationally modified with concomitant increases in activity and stability. To better understand the role of acetylation of Lys-317 in mouse p53, the effect of ionizing radiation (IR) on the thymocytes of p53(K317R) knock-in mice was studied at the global level. Using cleavable ICAT quantitative mass spectrometry, the effect of IR on protein levels in either the wild type or p53(K317R) thymocytes was determined. We found 102 proteins to be significantly affected by IR in the wild type thymocytes, including several whose expression has been shown to be directly regulated by p53. When the effects of IR in the wild type and p53(K317R) samples were compared, 46 proteins were found to be differently affected (p < 0.05). The p53(K317R) mutation has widespread effects on specific protein levels following IR, including the levels of proteins involved in apoptosis, transcription, and translation. Pathway analysis of the differently regulated proteins suggests an increase in p53 activity in the p53(K317R) thymocytes as well as a decrease in tumor necrosis factor alpha signaling. These results suggest that acetylation of Lys-317 modulates the functions of p53 and influences the cross-talk between the DNA damage response and other signaling pathways.

Picropodophyllin induces downregulation of the insulin-like growth factor 1 receptor: potential mechanistic involvement of Mdm2 and β-arrestin1

The insulin-like growth factor 1 receptor (IGF-1R) is crucial for growth and survival of malignant cells. Experience in targeting IGF-1R in cancer models has shown that strategies promoting downregulation of the receptor are much more efficient in inducing apoptosis than those inhibiting the IGF-1R activity. Recently, we found that the cyclolignan picropodophyllin (PPP) inhibits phosphorylation of IGF-1R and activation of downstream signaling without interfering with the highly homologous insulin receptor (IR). Furthermore, PPP treatment caused strong regression of tumor grafts and prolonged survival of animals with systemic tumor disease. Here we demonstrate that PPP also downregulates the IGF-1R, whereas the IR and several other receptors were not affected. PPP-induced IGF-1R downregulation required expression of the MDM2 E3 ligase, which recently was found to ubiquitinate and cause degradation of the IGF-1R. In addition knockdown of beta-arrestin1, the adaptor molecule known to bridges MDM2 and IGF-1R, prevented downregulation of the receptor and significantly decreased PPP-induced cell death. All together these data suggest that PPP downregulates IGF-1R by interfering with the action of beta-arrestin1/MDM2 as well as the achieved receptor downregulation contributes to the apoptotic effect of PPP.

The insulin-like growth factor-I-mTOR signaling pathway induces the mitochondrial pyrimidine nucleotide carrier to promote cell growth

The insulin/insulin-like growth factor (IGF) signaling pathway to mTOR is essential for the survival and growth of normal cells and also contributes to the genesis and progression of cancer. This signaling pathway is linked with regulation of mitochondrial function, but how is incompletely understood. Here we show that IGF-I and insulin induce rapid transcription of the mitochondrial pyrimidine nucleotide carrier PNC1, which shares significant identity with the essential yeast mitochondrial carrier Rim2p. PNC1 expression is dependent on PI-3 kinase and mTOR activity and is higher in transformed fibroblasts, cancer cell lines, and primary prostate cancers than in normal tissues. Overexpression of PNC1 enhances cell size, whereas suppression of PNC1 expression causes reduced cell size and retarded cell cycle progression and proliferation. Cells with reduced PNC1 expression have reduced mitochondrial UTP levels, but while mitochondrial membrane potential and cellular ATP are not altered, cellular ROS levels are increased. Overall the data indicate that PNC1 is a target of the IGF-I/mTOR pathway that is essential for mitochondrial activity in regulating cell growth and proliferation.

The role of the IGF system in cancer growth and metastasis: overview and recent insights

IGF-I receptor (IGF-IR) signaling and functions are mediated through the activities of a complex molecular network of positive (e.g., type I IGF) and negative (e.g., the type II IGF receptor, IGF-IIR) effectors. Under normal physiological conditions, the balance between the expression and activities of these molecules is tightly controlled. Changes in this delicate balance (e.g., overexpression of one effector) may trigger a cascade of molecular events that can ultimately lead to malignancy. In recent years, evidence has been mounting that the IGF axis may be involved in human cancer progression and can be targeted for therapeutic intervention. Here we review old and more recent evidence on the role the IGF system in malignancy and highlight experimental and clinical studies that provide novel insights into the complex mechanisms that contribute to its oncogenic potential. Controversies arising from conflicting evidence on the relevance of IGF-IR and its ligands to human cancer are discussed. Our review highlights the importance of viewing the IGF axis as a complex multifactorial system and shows that changes in the expression levels of any one component of the axis, in a given malignancy, should be interpreted with caution and viewed in a wider context that takes into account the expression levels, state of activation, accessibility, and functionality of other interacting components. Because IGF targeting for anticancer therapy is rapidly becoming a clinical reality, an understanding of this complexity is timely because it is likely to have an impact on the design, mode of action, and clinical outcomes of newly developed drugs.

PBK/TOPK promotes tumour cell proliferation through p38 MAPK activity and regulation of the DNA damage response

The contribution of the insulin-like growth-factor-I receptor (IGF-IR) to tumour progression is well documented. To identify new mediators of IGF-IR function in cancer, we recently isolated genes differentially expressed in cells overexpressing the IGF-IR. Among these was the serine/threonine kinase PBK/TOPK (PDZ-binding kinase/T-LAK cell-originated protein kinase), previously associated with highly proliferative cells and tissues. Here, we show that PBK is expressed at high levels in tumour cell lines compared with non-transformed cells. IGF-I could induce PBK expression only in transformed cells, whereas epidermal growth factor could induce PBK in non-transformed MCF-10A breast epithelial cells. Suppression of PBK expression using small interfering RNA did not prevent progression through the cell cycle, but caused decreased proliferation over time in culture, and reduced clonogenic growth in soft agarose. PBK knockdown impaired p38 activation after long-term stimulation with different growth factors and reduced DU145 cells motility. Suppressed PBK expression also resulted in an impaired response to DNA damage that was evident by the decreased generation of gamma-H2AX, increased DNA damage and decreased cell survival. Taken together, the data indicate that PBK is necessary for appropriate activation and function of the p38 pathway by growth factors. Thus, enhanced expression of PBK may facilitate tumour growth by mediating p38 activation and by helping cells to overcome DNA damage.

Combined In vivo Effect of A12, a Type 1 Insulin-Like Growth Factor Receptor Antibody, and Docetaxel against Prostate Cancer Tumors

PURPOSE

A human type 1 insulin-like growth factor receptor antibody (A12) has been shown to effectively inhibit human xenograft tumor growth, including androgen-dependent and androgen-independent prostate tumors. Docetaxel, either as a single agent or combined with others, has shown a survival benefit in prostate cancer patients. Based on these data, we investigated the combined in vivo effect of A12 and docetaxel on human androgen-independent and osseous prostate tumor growth.

EXPERIMENTAL DESIGN

To study human androgen-independent prostate cancer model, LuCaP35V tumors were implanted s.c. into castrated severe combined immunodeficient mice. When tumors reached about 100 mm3, animals were treated with vehicle control docetaxel (10 or 20 mg/kg) and docetaxel in combination with A12 (40 microg/kg) for 4 weeks. To study human osseous prostate cancer model, LuCaP 23.1 tumors were implanted intratibiae. When serum prostate-specific antigen reached 5 to 10 ng/mL, treatments were initiated.

RESULTS

A12 markedly augmented the inhibition of docetaxel on tumor growth. When docetaxel is combined with A12, the inhibition of tumor growth continued after treatment cessation, which was associated with continued apoptosis and decreased proliferation of tumor cells. Gene expression profiles indicated that the posttreatment suppression of tumor growth may be due to enhanced negative regulation of cell cycle progression- and/or cell survival-associated genes, some of which have been shown to induce resistance to docetaxel.

CONCLUSIONS

Our findings suggest that targeting type 1 insulin-like growth factor receptor can enhance the therapeutic effect of docetaxel on advanced prostate cancer. Our findings also suggest a potential mechanism to improve the treatment efficacy of docetaxel in prostate cancer.

Silencing of LASP-1 influences zyxin localization, inhibits proliferation and reduces migration in breast cancer cells

LIM and SH3 protein (LASP-1), initially identified from human breast cancer, is a specific focal adhesion protein involved in cell migration. LASP-1 is an actin binding protein, which also interacts with the proline-rich domains of zyxin, a scaffolding protein required for cell movement and gene transcription. In the present work, we analyzed the effect of LASP-1 on different human breast cancer cell lines. Transfection with LASP-1-specific siRNA resulted in a reduced protein level of LASP-1 in BT-20 and MCF-7 cell lines. The siRNA-treated cells were arrested in G2/M phase of cell cycle, and proliferation of the tumor cells was suppressed by 30-50% corresponding to around 50% of the cells being transfected successfully as seen by immunofluorescence. In addition, tumor cells showed a 50% reduced migration after siRNA treatment, while overexpression of LASP-1 in non-tumor PTK-2 cells, which do not express endogenous LASP-1, resulted in a significant increase in cell motility. LASP-1 silencing is accompanied with a reduced binding of the of LASP-1 binding partner zyxin to focal contacts without changes in actin stress fiber organization as observed in immunofluorescence experiments. The data provide evidence for an essential role of LASP-1 in tumor cell growth and migration, possibly by influencing the localization of zyxin.