Differential expression of IGFBP-5 and two human ESTs in thyroid glands with goiter, adenoma and papillary or follicular carcinomas

Single Cell RNA Sequencing of Papillary Cancer Mesenchymal Stem/Stromal Cells Reveals a Transcriptional Profile That Supports a Role for These Cells in Cancer Progression

Papillary thyroid cancer (PTC) contains mesenchymal stem/stromal cells (MSCs), but their contribution to PTC progression is not clear. In this study, we compared the transcriptional signatures of normal thyroid (NT) and PTC-derived MSCs with the aim of determining if these have distinct transcriptomes that might influence PTC progression. We used flow cytometry in combination with a panel of MSC clusters of differentiation (CD) markers and showed that both thyroid MSC populations expressed MSC markers and lacked expression of markers not normally expressed by MSCs. In addition, we determined that both MSC populations could differentiate to adipocytes and osteocytes. Analysis of single cell RNA sequencing data from both MSC populations revealed, regardless of tissue of origin, that both contained similar numbers of subpopulations. Cluster analysis revealed similarity in expression of both MSC populations for stromal markers, the vascular marker VEGFA and the smooth muscle marker CALD1, while smaller subpopulations expressed markers of more lineage-committed thyroid cells. PTC MSCs also showed upregulated expression of 28 genes, many of which are known to be involved in epithelial-mesenchymal transition (EMT) and/or disease progression in several types of cancers, including but not limited to breast cancer, gastric cancer, cervical carcinoma, bladder cancer and thyroid cancer. This included several members of the S100 and IGFBP gene families. Taken together, these data support a role for PTC MSCs in PTC progression.

Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications

To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases.

Differential gene expression profile of multinodular goiter

Introduction

The goiter, a neglected heterogeneous molecular disease, remains a major indication for thyroidectomies in its endemic regions.

Objectives

This study analyzed differential gene expression in surgical specimens diagnosed with multi nodular and compared the data to that of thyroid tissue without multinodular goiter from patients undergoing thyroidectomy in Manaus-AM, Brazil using RNA-seq technology.

Methodology

The transcriptome information of the surgical specimen fragments with and without multinodular goiter was accessed by Illumina HiSeq 2000 New Generation Sequencing (NGS) using the RNA-seq NEBNext^® Ultra^™ RNA Library Prep Kit for Illumina^®—#E7530L protocol and differential gene expression analysis.

Results

Differences were found between the gene expression profiles of the diseased tissues and those of the healthy control tissues; at least 70 genes were differentially expressed. The HOTS gene was expressed only in multinodular goiter tissues (p < 0.05).

Conclusion

These results demonstrate that the gene expression profile of multinodular goiter is pro-tumoral and that HOTS can play a central role in multinodular goiter development.

Fine-mapping of two differentiated thyroid carcinoma susceptibility loci at 2q35 and 8p12 in Europeans, Melanesians and Polynesians

Differentiated thyroid carcinoma (DTC) incidence is characterized by wide ethnic and geographic variations, with high incidence rates observed in Oceanian populations. Genome-wide association studies (GWAS) identified mainly four DTC susceptibility loci at 9q22.33, 14q13.3, 2q35 and 8p12. Here we performed fine-mapping of the 2q35 and 8p12 loci in the population of the EPITHYR consortium that includes Europeans, Melanesians and Polynesians to identify likely causal variants for DTC risk. We conducted a colocalization analysis using eQTLs data to determine the SNPs with the highest probability of causality. At 2q35, we highlighted rs16857609 located in DIRC3. This SNP has a high probability of causality in the three populations, and a significant association in Europeans (OR = 1.4, p = 1.9 x 10-10). It is also associated with expression of DIRC3 and of the nearby gene IGFBP5 in thyroid tumour cells. At 8p12, we identified rs7844425 which was significantly associated with DTC in Europeans (OR = 1.32, p = 7.6 x 10-8) and rs2439304, which was highlighted by the colocalization analysis but only moderately associated with DTC in our dataset (OR = 1.2, p = 0.001). These SNPs are linked to the expression of NRG1 in thyroid tissue. Hence, our study identified novel variants at 2q35 and 8p12 to be prioritized for further functional studies.

IGF Bioregulation System in Benign and Malignant Thyroid Nodular Disease: A Systematic Review

BACKGROUND/AIM

The insulin-like growth factor bioregulation system is implicated in cancer biology. Herein, we aim to review the evidence on the expression of the insulin-like growth factor 1 and 2 (IGF1 and IGF2), their receptors (IGF-Rs) and IGF-binding proteins (IGFBPs) in thyroid tissue and their possible association with benign and malignant thyroid nodular diseases.

MATERIALS AND METHODS

We systematically reviewed Pubmed and Scopus databases up to May 2020. A total of 375 articles were retrieved and analyzed.

RESULTS

Among 375 articles, 45 were included in this systematic review study. IGF1 was investigated in 31 studies, IGF2 in 1, IGF1 receptor in 15 and IGF-binding proteins in 13 articles. IGF1 expression in humans was dependent on the number and compound of benign nodules as well as the method of measurement. In differentiated thyroid carcinoma, a positive correlation between IGF1 and immunohistological stage was documented in some studies while in others only a positive trend was observed. IGF-1R and IGFBPs expression was higher in malignant rather than benign lesions. There was only a positive trend for increased IGF2 expression in malignancy, while IGFBPs were in most studies statistically increased in various cancer types compared to benign nodular disease.

CONCLUSION

The present data demonstrate that in most studies there is statistically positive expression of IGF-1 and less of IGF-2 in thyroid cancer compared to normal thyroid tissue.

Knockdown of lncRNA UCA1 inhibits proliferation and invasion of papillary thyroid carcinoma through regulating miR-204/IGFBP5 axis

Background

Long noncoding RNA (LncRNA) UCA1 has been reported to function as an oncogene in multiple cancers. However, the biological roles and underlying mechanism of UCA1 in papillary thyroid carcinoma (PTC) remain unclear. This study aimed to investigate the underlying function of UCA1 on thyroid cancer progression.

Materials and methods

A series of experiments involving Cell Counting Kit-8, wound-healing, and transwell invasion assays were conducted to determine the cellular capabilities of proliferation, migration, and invasion, respectively. Binding sites between UCA1 and miR-204 were identified using a luciferase reporter system, whereas mRNA and protein expression of target genes were determined by real-time quantitative reverse transcription-PCR (qRT-PCR) and Western blot, respectively.

Results

The results revealed that UCA1 was upregulated in PTC tissue and cell lines. UCA1 knockdown significantly suppressed the cell proliferation, migration, and invasion of TPC-1 cells. Bioinformatics analysis and luciferase reporter assay verified the complementary binding within UCA1 and miR-204 at the 3′-UTR. Moreover, miR-204 inhibition reversed the UCA1 knockdown-mediated inhibitory effect on cell proliferation, migration, and invasion. We also found that UCA1 could regulate expression of IGFBP5, a direct target of miR-204 in PTC.

Conclusion

Our study demonstrated that UCA1 exerts activity of oncogenes in PTC through regulating miR-204/IGFBP5 axis.

Association of Established Thyroid-stimulating Hormone and Free Thyroxine Genetic Variants with Hashimoto's Thyroiditis

Hashimoto's thyroiditis (HT), the most frequent autoimmune thyroid disease (AITD), is characterized by chronic inflammation of the thyroid gland that usually results in hypothyroidism. Thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels are used as clinical determinants of thyroid function. The main aim of this study was to explore the association of established TSH and FT4 genetic variants with HT. We performed a case-control analysis using 23 genetic markers in 200 HT patients and 304 controls. Additionally, we tested the association of selected variants with several thyroid-related quantitative traits in HT cases only. Two genetic variants showed nominal association with HT: rs11935941 near NR3C2 gene (p = 0.0034, OR = 0.57, 95% CI = 0.39-0.83) and rs1537424 near MBIP gene (p = 0.0169, OR = 0.72, 95% CI = 0.55-0.94). Additionally, three SNPs showed nominal association with thyroglobulin antibody (TgAb) levels: rs4804416 in INSR gene (p = 0.0073, β = -0.51), rs6435953 near IGFBP5 gene (p = 0.0081, β = 0.75), and rs1537424 near MBIP gene (p = 0.0117, β = 0.49). GLIS3 genetic variant rs10974423 showed nominal association with thyroid peroxidase antibody (TPOAb) levels (p = 0.0465, β = -0.56) and NRG1 genetic variant rs7825175 was nominally associated with thyroid gland volume (p = 0.0272, β = -0.18). All detected loci were previously related to thyroid function or pathology. Findings from our study suggest biological relevance of NR3C2 and MBIP with HT, although these loci require additional confirmation in a larger replication study.

Flaxseed and its components differentially affect estrogen targets in pre-neoplastic hen ovaries

Flaxseed has been studied for decades for its health benefits that include anti-cancer, cardio-protective, anti-diabetic, anti-inflammatory properties. The biologically active components that mediate these effects are the omega-3 fatty acids and the lignan, secoisolariciresinol diglucoside. We have previously shown that whole flaxseed supplemented diet decreases the severity and incidence of ovarian cancer while a 15% dose of flaxseed is most protective against inflammation and estrogen-induced chemical and genotoxicity. The objective of this study was to dissect the independent effects of the two flaxseed components on estrogen signaling and metabolism. Two and half year old hens were fed either a control diet, 15% whole flaxseed diet, defatted flax meal diet or 5% flax oil diet for 3 months after which the animals were sacrificed and blood and tissues were harvested. Whole flaxseed diet caused a decrease in expression of ERα. ERα target gene expression was assessed using RT(2) profiler PCR array. Some targets involved in the IGF/insulin signaling pathway (IRS1, IGFBP4, IGFBP5) were downregulated by flaxseed and its components. Flaxseed diet also downregulated AKT expression. A number of targets related to NF-kB signaling were altered by flaxseed diet including a series of targets implicated in cancer. Whole flaxseed diet also affected E2 metabolism by increasing CYP1A1 expression with a corresponding increase in the onco-protective E2 metabolite, 2-methoxyestradiol. The weak anti-estrogens, enterolactone, enterodiol and 2-methoxyestradiol, might be working synergistically to generate a protective effect on the ovaries from hens on whole flaxseed diet by altering the estrogen signaling and metabolism.

Pitavastatin Regulates Ang II Induced Proliferation and Migration via IGFBP-5 in VSMC

Angiotensin II (Ang II), a key mediator of hypertensive, causes structural changes in the arteries (vascular remodeling), which involve alterations in cell growth, vascular smooth muscle cell (VSMC) hypertrophy. Ang II promotes fibrotic factor like IGFBP5, which mediates the profibrotic effects of Ang II in the heart and kidneys, lung and so on. The purpose of this study was to identify the signaling pathway of IGFBP5 on cell proliferation and migration of Ang II-stimulated VSMC. We have been interested in Ang II-induced IGFBP5 and were curious to determine whether a Pitavastatin would ameliorate the effects. Herein, we investigated the question of whether Ang II induced the levels of IGFBP5 protein followed by proliferation and migration in VSMC. Pretreatment with the specific Angiotensin receptor type 1 (AT1) inhibitor (Losartan), Angiotensin receptor type 2 (AT2) inhibitor (PD123319), MAPK inhibitor (U0126), ERK1/2 inhibitor (PD98059), P38 inhibitor (SB600125) and PI3K inhibitor (LY294002) resulted in significantly inhibited IGFBP5 production, proliferation, and migration in Ang II-stimulated VSMC. In addition, IGFBP5 knockdown resulted in modulation of Ang II induced proliferation and migration via IGFBP5 induction. In addition, Pitavastatin modulated Ang II induced proliferation and migration in VSMC. Taken together, our results indicated that Ang II induces IGFBP5 through AT1, ERK1/2, P38, and PI3K signaling pathways, which were inhibited by Pitavastatin. These findings may suggest that Pitavastatin has an effect on vascular disease including hypertension.

MiR-204-5p suppresses cell proliferation by inhibiting IGFBP5 in papillary thyroid carcinoma

microRNAs (miRNAs) are frequently dysregulated in human malignancies. It was recently shown that miR-204-5p is downregulated in papillary thyroid carcinoma (PTC); however, the functional significance of this observation is not known. This study investigated the role of miR-204-5p in PTC. Overexpressing miR-204-5p suppressed PTC cell proliferation and induced cell cycle arrest and apoptosis. The results of a luciferase reporter assay showed that miR-204-5p can directly bind to the 3' untranslated region (UTR) of insulin-like growth factor-binding protein 5 (IGFBP5) mRNA, and IGFBP5 overexpression partially reversed the growth-inhibitory effects of miR-204-5p. These results indicate that miR-204-5p acts as a tumor suppressor in PTC by regulating IGFBP5 expression and that miR-204-5p can potentially serve as an antitumorigenic agent in the treatment of PTC.

IGFBP5 domains exert distinct inhibitory effects on the tumorigenicity and metastasis of human osteosarcoma

Osteosarcoma (OS) is the most common primary malignancy of bone. We investigated the roles of insulin-like growth factor binding protein 5 (IGFBP5) domains in modulating OS tumorigenicity and metastasis. The N-terminal (to a lesser extent the C-terminal) domain inhibited cell proliferation and induced apoptosis while the C-terminal domain inhibited cell migration and invasion. The Linker domain had no independent effects. In vivo, the N-terminal domain decreased tumor growth without affecting pulmonary metastases while the C-terminal domain inhibited tumor growth and metastases. In summary, the N- and C-terminal domains modulated OS tumorigenic phenotypes while the C-terminal domain inhibited OS metastatic phenotypes.

A meta-analysis of thyroid-related traits reveals novel loci and gender-specific differences in the regulation of thyroid function

Thyroid hormone is essential for normal metabolism and development, and overt abnormalities in thyroid function lead to common endocrine disorders affecting approximately 10% of individuals over their life span. In addition, even mild alterations in thyroid function are associated with weight changes, atrial fibrillation, osteoporosis, and psychiatric disorders. To identify novel variants underlying thyroid function, we performed a large meta-analysis of genome-wide association studies for serum levels of the highly heritable thyroid function markers TSH and FT4, in up to 26,420 and 17,520 euthyroid subjects, respectively. Here we report 26 independent associations, including several novel loci for TSH (PDE10A, VEGFA, IGFBP5, NFIA, SOX9, PRDM11, FGF7, INSR, ABO, MIR1179, NRG1, MBIP, ITPK1, SASH1, GLIS3) and FT4 (LHX3, FOXE1, AADAT, NETO1/FBXO15, LPCAT2/CAPNS2). Notably, only limited overlap was detected between TSH and FT4 associated signals, in spite of the feedback regulation of their circulating levels by the hypothalamic-pituitary-thyroid axis. Five of the reported loci (PDE8B, PDE10A, MAF/LOC440389, NETO1/FBXO15, and LPCAT2/CAPNS2) show strong gender-specific differences, which offer clues for the known sexual dimorphism in thyroid function and related pathologies. Importantly, the TSH-associated loci contribute not only to variation within the normal range, but also to TSH values outside the reference range, suggesting that they may be involved in thyroid dysfunction. Overall, our findings explain, respectively, 5.64% and 2.30% of total TSH and FT4 trait variance, and they improve the current knowledge of the regulation of hypothalamic-pituitary-thyroid axis function and the consequences of genetic variation for hypo- or hyperthyroidism.

Levels of thyroid hormones are tightly regulated by TSH produced in the pituitary, and even mild alterations in their concentrations are strong indicators of thyroid pathologies, which are very common worldwide. To identify common genetic variants associated with the highly heritable markers of thyroid function, TSH and FT4, we conducted a meta-analysis of genome-wide association studies in 26,420 and 17,520 individuals, respectively, of European ancestry with normal thyroid function. Our analysis identified 26 independent genetic variants regulating these traits, several of which are new, and confirmed previously detected polymorphisms affecting TSH (within the PDE8B gene and near CAPZB, MAF/LOC440389, and NR3C2) and FT4 (within DIO1) levels. Gender-specific differences in the genetic effects of several variants for TSH and FT4 levels were identified at several loci, which offer clues to understand the known sexual dimorphism in thyroid function and pathology. Of particular clinical interest, we show that TSH-associated loci contribute not only to normal variation, but also to TSH values outside reference range, suggesting that they may be involved in thyroid dysfunction. Overall, our findings add to the developing landscape of the regulation of thyroid homeostasis and the consequences of genetic variation for thyroid related diseases.

Functional roles and clinical values of insulin-like growth factor-binding protein-5 in different types of cancers

Insulin-like growth factor-binding proteins (IGFBPs) are critical regulators of the mitogenic activity of insulin-like growth factors (IGFs). IGFBP5, one of these IGFBPs, has special structural features, including a nuclear transport domain, heparin-binding motif, and IGF/extracellular matrix/acid-labile subunit-binding sites. Furthermore, IGFBP5 has several functional effects on carcinogenesis and even normal cell processes, such as cell growth, death, motility, and tissue remodeling. These biological effects are sometimes related with IGF (IGF-dependent effects) and sometimes not (IGF-independent effects). The functional role of IGFBP5 is most likely determined in a cell-type and tissue-type specific manner but also depends on cell context, especially in terms of the diversity of interacting proteins and the potential for nuclear localization. Clinical findings show that IGFBP5 has the potential to be a useful clinical biomarker for predicting response to therapy and clinical outcome of cancer patients. In this review, we summarize the functional diversity and clinical importance of IGFBP5 in different types of cancers.

Insulin-like growth factor binding protein 5 suppresses tumor growth and metastasis of human osteosarcoma

Osteosarcoma (OS) is the most common primary malignancy of bone. There is a critical need to identify the events that lead to the poorly understood mechanism of OS development and metastasis. The goal of this investigation is to identify and characterize a novel marker of OS progression. We have established and characterized a highly metastatic OS subline that is derived from the less metastatic human MG63 line through serial passages in nude mice via intratibial injections. Microarray analysis of the parental MG63, the highly metastatic MG63.2 subline, as well as the corresponding primary tumors and pulmonary metastases revealed insulin-like growth factor binding protein 5 (IGFBP5) to be one of the significantly downregulated genes in the metastatic subline. Confirmatory quantitative RT-PCR on 20 genes of interest demonstrated IGFBP5 to be the most differentially expressed and was therefore chosen to be one of the genes for further investigation. Adenoviral mediated overexpression and knockdown of IGFBP5 in the MG63 and MG63.2 cell lines, as well as other OS lines (143B and MNNG/HOS) that are independent of our MG63 lines, were employed to examine the role of IGFBP5. We found that overexpression of IGFBP5 inhibited in vitro cell proliferation, migration and invasion of OS cells. Additionally, IGFBP5 overexpression promoted apoptosis and cell cycle arrest in the G1 phase. In an orthotopic xenograft animal model, overexpression of IGFBP5 inhibited OS tumor growth and pulmonary metastases. Conversely, siRNA-mediated knockdown of IGFBP5 promoted OS tumor growth and pulmonary metastases in vivo. Immunohistochemical staining of patient-matched primary and metastatic OS samples demonstrated decreased IGFBP5 expression in the metastases. These results suggest 1) a role for IGFBP5 as a novel marker that has an important role in the pathogenesis of OS, and 2) that the loss of IGFBP5 function may contribute to more metastatic phenotypes in OS.

Tumor-associated retinal astrocytes promote retinoblastoma cell proliferation through production of IGFBP-5

Retinoblastomas consist of cone-like neoplastic cells and diverse non-neoplastic cells whose roles in tumorigenesis have not been defined. Here, we investigated the glial cells that constitute 2% to 3% of the cells in retinoblastoma tumors, including their origin, their relationship to a potential retinoblastoma stem cell population, and their effects on tumor cell proliferation. Retinoblastoma glia consistently expressed the retinal astrocyte marker Pax2 but inconsistently expressed the Müller cell and occasional astrocyte marker CRALBP. Many of the glia expressed the stem cell-associated Sox2 but nevertheless were non-neoplastic as they coexpressed Rb and/or retained two RB1 alleles. Conversely, the glia were distinct from the non-neoplastic cells that strongly expressed the stem cell-associated ABCG2. Adherent Pax2(+),Sox2(+),Rb(+) glia readily grew from explanted retinoblastomas and produced soluble factors that enhanced the proliferation of cocultured retinoblastoma cells. This effect was emulated by normal retinal glia and appeared to be mediated by insulin-like growth factor binding protein-5 (IGFBP-5), as it was mimicked by recombinant IGFBP-5 and mitigated by neutralizing IGFBP-5 antibody. As glia-derived IGFBP-5 was earlier found to promote photoreceptor survival, our findings indicate that retinal astrocytes enhance the proliferation of cone-like retinoblastoma cells by deploying a factor that also provides trophic support to the tumor cells' non-neoplastic counterparts. These observations suggest that a tissue-specific microenvironmental feature cooperates with oncogenic mutations in a cancer cell of origin to promote retinoblastoma tumorigenesis.

Role of insulin-like growth factor-binding protein 5 (IGFBP5) in organismal and pancreatic beta-cell growth

A family of IGF-binding proteins (IGFBP) exerts biological actions both dependent on and independent of IGF-I. A major effector of the insulin/IGF-I signaling pathway, the serine/threonine protein kinase Akt, mediates cellular processes such as glucose uptake, protein synthesis, cell survival, and growth. IGF-I is required for normal organismal growth, and in the pancreatic beta-cell, the insulin/IGF-I signaling pathway is critical for normal and adaptive maintenance of beta-cell mass. Expression of myrAkt1, an activated form of Akt, in the endocrine pancreas drives beta-cell expansion through dramatic increases in both islet and beta-cell size and number. Herein we present a comparative expression profiling of myrAkt1 transgenic islets that demonstrates the increased abundance of transcripts encoding proteins associated with growth, suppression of apoptosis, RNA processing, and metabolism. Although IGFBP5 is identified as a gene induced by Akt1 activation in the beta-cell, Igfbp5 expression is not necessary for myrAkt1 to augment beta-cell size or mass in vivo. However, in the absence of Igfbp5, mice demonstrate an increase in size and mild glucose intolerance. This is accentuated during diet-induced obesity, when Igfbp5-deficient mice have increased adiposity compared with wild-type mice on the same diet. These studies reveal a novel role for Igfbp5 in the control of growth and metabolism.

IGF-independent effects of insulin-like growth factor binding protein-5 (Igfbp5) in vivo

IGF activity is regulated tightly by a family of IGF binding proteins (IGFBPs). IGFBP-5 is the most conserved of these and is up-regulated significantly during differentiation of several key lineages and in some cancers. The function of IGFBP-5 in these physiological and pathological situations is unclear, however, several IGFBP-5 sequence motifs and studies in vitro suggest IGF-independent actions. Therefore, we aimed to compare the phenotypes of mice overexpressing wild-type Igfbp5 or an N-terminal mutant Igfbp5 with negligible IGF binding affinity. Both significantly inhibited growth, even at low expression levels. Even though wild-type IGFBP-5 severely disrupted the IGF axis, we found no evidence for interaction of mutant IGFBP-5 with the IGF system. Further, overexpression of wild-type IGFBP-5 rescued the lethal phenotype induced by "excess" IGF-II in type 2 receptor-null mice; mutant IGFBP-5 overexpression could not. Therefore, wild-type IGFBP-5 provides a very effective mechanism for the inhibition of IGF activity and a powerful in vivo mechanism to inhibit IGF activity in pathologies such as cancer. This study is also the first to suggest significant IGF-independent actions for IGFBP-5 during development.

Multifunctional roles of insulin-like growth factor binding protein 5 in breast cancer

The insulin-like growth factor axis, which has been shown to protect cells from apoptosis, plays an essential role in normal cell physiology and in cancer development. The family of insulin-like growth factor binding proteins (IGFBPs) has been shown to have a diverse spectrum of functions in cell growth, death, motility, and tissue remodeling. Among the six IGFBP family members, IGFBP-5 has recently been shown to play an important role in the biology of breast cancer, especially in breast cancer metastasis; however, the exact mechanisms of action remain obscure and sometimes paradoxical. An in-depth understanding of IGFBP-5 would shed light on its potential role as a target for breast cancer therapeutics.

Induction of cellular senescence by insulin-like growth factor binding protein-5 through a p53-dependent mechanism

The insulin-like growth factor (IGF) signaling pathway plays a crucial role in the regulation of cell growth, differentiation, apoptosis, and aging. IGF-binding proteins (IGFBPs) are important members of the IGF axis. IGFBP-5 is up-regulated during cellular senescence in human dermal fibroblasts and endothelial cells, but the function of IGFBP-5 in cellular senescence is unknown. Here we show that IGFBP-5 plays important roles in the regulation of cellular senescence. Knockdown of IGFBP-5 in old human umbilical endothelial cells (HUVECs) with IGFBP-5 micro-RNA lentivirus caused partial reduction of a variety of senescent phenotypes, such as changes in cell morphology, increases in cell proliferation, and decreases in senescence-associated beta-galactosidase (SA-beta-gal) staining. In addition, treatment with IGFBP-5 protein or up-regulation of IGFBP-5 in young cells accelerates cellular senescence, as confirmed by cell proliferation and SA-beta-gal staining. Premature senescence induced by IGFBP-5 up-regulation in young cells was rescued by knockdown of p53, but not by knockdown of p16. Furthermore, atherosclerotic arteries exhibited strong IGFBP-5-positive staining along intimal plaques. These results suggest that IGFBP-5 plays a role in the regulation of cellular senescence via a p53-dependent pathway and in aging-associated vascular diseases.

Effect of all-trans retinoic acid on sodium/iodide symporter expression, radioiodine uptake and gene expression profiles in a human anaplastic thyroid carcinoma cell line

The plasma membrane glycoprotein sodium/iodide symporter (NIS) is crucial for thyroid hormone biosynthesis and mediates the iodide uptake of thyrocytes. It has been shown that retinoic acid (RA) alters NIS gene expression in thyroid carcinoma lines and stimulates their iodide uptake. Here, we generated an ARO human thyroidal cancer cell line that expresses the NIS gene (ARO-NIS) and found that its baseline 125I uptake was threefold higher than that of its parental ARO cells. However, a 1-microM all-trans retinoic acid (tRA) treatment significantly increased this 125I uptake up to approximately approximately 6.5-fold on Day 3. tRA also elevated NIS mRNA expression in ARO-NIS cells, with peaks of expression being observed on Day 3. To investigate the underlying genomic mechanisms involved in these tRA-induced phenotypic changes, we subjected tRA-treated and untreated ARO-NIS cells to cDNA microarray analysis. Of 1152, genes spotted onto the microarray membrane, 18 were up-regulated (z ratio>2.0) and 33 were down-regulated (z ratio<-2.0) in ARO-NIS cells after 3 days of tRA treatment. More specifically, tRA increased the expression of BCL3, CSRP3, v-fos, and CDK5 genes and decreased the expression of the FGF12 and IGFBP6 genes. Thus, tRA treatment of human anaplastic thyroid carcinoma cells stably expressing the NIS gene significantly elevates their NIS-mediated radioiodine uptake and alters the expression of many genes involved in cell growth and cellular differentiation. Therefore, tRA treatment and NIS gene transfection are potential tools for the diagnosis and treatment of thyroid cancer.

Insulin-like growth factor-binding protein-5 (IGFBP-5): a critical member of the IGF axis

The six members of the insulin-like growth factor-binding protein family (IGFBP-1-6) are important components of the IGF (insulin-like growth factor) axis. In this capacity, they serve to regulate the activity of both IGF-I and -II polypeptide growth factors. The IGFBPs are able to enhance or inhibit the activity of IGFs in a cell- and tissue-specific manner. One of these proteins, IGFBP-5, also has an important role in controlling cell survival, differentiation and apoptosis. In this review, we report on the structural and functional features of the protein which are important for these effects. We also examine the regulation of IGFBP-5 expression and comment on its potential role in tumour biology, with special reference to work with breast cancer cells.

Effect of NS398 on metastasis-associated gene expression in a human colon cancer cell line

AIM: To investigate the effect of NS398 on the metastasis-associated gene expression in LoVo colorectal cancer cells.

METHODS: LoVo cells were treated with NS398 at the concentration of 100 mmol/L for 24 and 48 h respectively. Total RNA was extracted with TRIzol reagents and reverse transcribed with Superscript II and hybridized with cDNA microarray (containing oncogenes, tumor suppressor genes, signal transduction molecules, adhesive molecules, growth factors, and ESTs) fabricated in our laboratory. After normalization, the ratio of gene expression of NS398 treated to untreated LoVo cells was either 2-fold up or 0.5-fold down was defined as the differentially expressed genes. Semi-quantitative RT-PCR was used to validate the microarray results.

RESULTS: Among the 447 metastasis-associated genes, 9 genes were upregulated and 8 genes were downregulated in LoVo cells treated with NS398 for 24 h compared to untreated cells. While 31 genes were upregulated and 14 genes were downregulated in LoVo cells treated with NS398 for 48 h. IGFBP-5, PAI-2, JUN, REL, BRCA1, and BRCA2 might be the new targets of NS398 in treatment of colorectal cancer.

CONCLUSION: NS398 might exert its anti-metastasis effect on colorectal cancer by affecting several metastasis-associated gene expression.

Gene expression analysis reveals evidence for increased expression of cell cycle-associated genes and Gq-protein-protein kinase C signaling in cold thyroid nodules

In contrast to the molecular etiology of autonomously functioning thyroid nodules, the molecular cause of cold thyroid nodules (CTNs), their benign, functional inactive counterparts, are so far largely unknown. Because of the partially dedifferentiated phenotype of CTNs, alterations in signaling cascades that favor proliferation, but not differentiation, are likely candidates for tumor induction and progression. The importance of RAS mutations for the development of benign nodules with follicular histology is still in question. However, differentially expressed genes in the context of their signaling cascades could define aberrant signaling in CTNs. Therefore, we investigated gene expression in 22 CTNs and their normal surrounding tissue using Affymetrix GeneChips. Most prominently, data analysis revealed an increased expression of cell cycle-associated genes and a special relevance of protein kinase C signaling, whereas no evidence of RAS-MAPK signaling in CTNs was found. Moreover, we determined 31 differentially regulated genes in CTNs, including several histone mRNAs. Taken together, these results explain recent findings showing an increased proliferation in CTNs and draw attention to protein kinase C signaling, but away from RAS-MAPK signaling, as being involved in the etiology of CTNs.

Expression profile of malignant and non-malignant diseases of the thyroid gland reveals altered expression of a common set of genes in goiter and papillary carcinomas

Using cDNA microarrays with 3800 cDNA fragments, we determined the expression profile of normal thyroid tissue, goiter, adenoma and papillary carcinoma (10 samples from each class). After background correction and statistical analysis, we identified a set of 160 genes as being differentially expressed in all pair-wise comparisons. Here we demonstrate that, at least on the basis of these differentially expressed genes, a positive correlation between goiter and papillary carcinomas could be observed. We identified a common set of genes whose expression is diminished in both goiter and papillary carcinomas as compared to normal thyroid tissue. Moreover, no genes with inverse correlation in samples from goiter and papillary carcinomas could be detected. Using Real-Time PCR and/or tissue microarrays, we confirmed the altered expression of some of the identified genes. Of notice, we demonstrate that the reduced mRNA levels of p27(kip1) observed in papillary carcinomas as compared to either goiter or normal thyroid tissues (P<0.001) is accompanied by an altered protein distribution within the cell. In papillary carcinomas, P27(KIP1) is preferentially cytoplasmic as opposed to goiter or normal thyroid tissue, where P27(KIP1) is preferentially located in the nucleus. The exploitation of the data presented here could contribute to the understanding of the molecular events related to thyroid diseases and gives support to the notion that common molecular events might be related to the frequent observation of areas of papillary carcinomas in the gland of patients with goiter.

Partitioning of IGFBP-5 actions in myogenesis: IGF-independent anti-apoptotic function

Igfbp5 is upregulated during the differentiation of several key cell lineages and in some tumours; the function of IGFBP-5 in these physiological and pathological situations is unknown. Since IGFBP-5 contains sequence motifs consistent with IGF-independent actions, the aim of these studies was to distinguish between IGF-dependent and -independent actions of IGFBP-5. Myc-tagged wild-type (termed wtIGFBP-5) and non-IGF binding mouse Igfbp5 (termed mutIGFBP-5) cDNAs were generated and used to transfect C2 myoblasts, a cell line that undergoes differentiation to myotubes in an IGF- and IGFBP-5-regulated manner. WtIGFBP-5, but not mutIGFBP-5, inhibited myogenesis, as assessed by cell morphology, MHC immunocytochemistry and caveolin 3 expression. However, both wt- and mutIGFBP-5 increased cell survival and decreased apoptosis, as indicated by decreased caspase-3 activity and cell surface annexin V binding. Further examination of apoptotic pathways revealed that wt- and mutIGFBP-5 ameliorated the increase in caspase-9 but not the modest increase in caspase-8 during myogenesis, suggesting that IGFBP-5 increased cell survival via inhibition of intrinsic cell death pathways in an IGF-independent manner. The relationship between IGF-II and IGFBP-5 was examined further by cotransfecting C2 myoblasts with antisense Igf2 (previously established to induce increased cell death) and Igfbp5; both wt- and mutIGFBP-5 conferred equivalent protection against the decreased cell survival and increased apoptosis. In conclusion, we have partitioned IGFBP-5 action in myogenesis into IGF-dependent inhibition of differentiation and IGF-independent cell survival. Our findings suggest that, by regulation of cell survival, IGFBP-5 has an autonomous role in the regulation of cell fate in development and in tumourigenesis.