Insulin-like growth factor II mediates epidermal growth factor-induced mitogenesis in cervical cancer cells

Ketosis Suppression and Ageing (KetoSAge): The Effects of Suppressing Ketosis in Long Term Keto-Adapted Non-Athletic Females

Most studies on ketosis have focused on short-term effects, male athletes, or weight loss. Hereby, we studied the effects of short-term ketosis suppression in healthy women on long-standing ketosis. Ten lean (BMI 20.5 ± 1.4), metabolically healthy, pre-menopausal women (age 32.3 ± 8.9) maintaining nutritional ketosis (NK) for > 1 year (3.9 years ± 2.3) underwent three 21-day phases: nutritional ketosis (NK; P1), suppressed ketosis (SuK; P2), and returned to NK (P3). Adherence to each phase was confirmed with daily capillary D-beta-hydroxybutyrate (BHB) tests (P1 = 1.9 ± 0.7; P2 = 0.1 ± 0.1; and P3 = 1.9 ± 0.6 pmol/L). Ageing biomarkers and anthropometrics were evaluated at the end of each phase. Ketosis suppression significantly increased: insulin, 1.78-fold from 33.60 (± 8.63) to 59.80 (± 14.69) pmol/L (p = 0.0002); IGF1, 1.83-fold from 149.30 (± 32.96) to 273.40 (± 85.66) µg/L (p = 0.0045); glucose, 1.17-fold from 78.6 (± 9.5) to 92.2 (± 10.6) mg/dL (p = 0.0088); respiratory quotient (RQ), 1.09-fold 0.66 (± 0.05) to 0.72 (± 0.06; p = 0.0427); and PAI-1, 13.34 (± 6.85) to 16.69 (± 6.26) ng/mL (p = 0.0428). VEGF, EGF, and monocyte chemotactic protein also significantly increased, indicating a pro-inflammatory shift. Sustained ketosis showed no adverse health effects, and may mitigate hyperinsulinemia without impairing metabolic flexibility in metabolically healthy women.

PLAGL1 is associated with prognosis and cell proliferation in pancreatic adenocarcinoma

BACKGROUND

Emerging evidence has shown the crucial roles of pleomorphic adenoma gene (PLAG) family genes in multiple cancers. However, their functions and mechanisms in pancreatic adenocarcinoma (PAAD) remain poorly understood.

METHODS

We analyzed the expression levels of PLAG family genes in both The Cancer Genome Atlas (TCGA) database and a Gene Expression Omnibus (GEO) database, and confirmed the results in our three independent cohorts of 382 PAAD tissues and 362 adjacent nontumor pancreatic tissues. Integrated analyses were carried out to explore the function, mechanism and prognostic value of the selected PLAG family gene in PAAD patients.

RESULTS

By analyzing the TCGA and GEO databases, PLAGL1 was identified to be downregulated in PAAD tissues, and its decreasing levels of both mRNA and protein were verified in our three independent PAAD cohorts. PLAGL1 expression was inversely correlated with clinicopathological factors including the Ki67⁺ cell rate and pathologic stage. Further GSEA of the TCGA-PAAD cohort demonstrated that multiple signaling pathways implicated in cell proliferation were enriched in the lower PLAGL1 expressing PAAD group. Moreover, we demonstrated that PLAGL1 expression was obviously negatively associated with patients' overall survival outcome in both the TCGA-PAAD cohort and our verification cohorts. Additionally, through MTS and BrdU assays, we further demonstrated in vitro that PLAGL1 had the impact of preventing the proliferation of pancreatic cancer cells.

CONCLUSIONS

Our present study suggested that downregulated PLAGL1 might act as a biomarker in predicts poor prognosis and one of important factors in increasing cell proliferation in PAAD. This study provides us with a novel prognostic marker and therapeutic strategy for PAAD, which deserves further study.

Targeting IGF-1 signaling pathways in gynecologic malignancies

INTRODUCTION

The signaling pathways of the insulin-like growth factors (IGF) have been implicated in the etiology of a number of epithelial neoplasms including prostate, breast, colon and more recently, gynecologic cancers. The insulin-like growth factor-1 receptor (IGF-1R) is expressed in most transformed cells, where it displays potent anti-apoptotic, cell-survival and potentially, transforming activities. IGF-1R expression and activation are typical hallmarks associated with tumor initiation and progression. Multiple approaches have been used to abrogate IGF-1R signaling for targeted cancer therapy including antibodies and small molecule tyrosine kinase inhibitors. These novel IGF-1R targeting agents have produced significant experimental and clinical results in many cancers and generated considerable optimism in the field of cancer therapy.

AREAS COVERED

The authors will review important research advances regarding the role of the IGF axis in cancer, particularly preclinical and clinical studies in cervical, uterine and ovarian cancers. The significance of tumor expression and circulating levels of the IGF pathway as well as targeting therapies of the IGF axis in the gynecologic cancers will be discussed.

EXPERT OPINION

Accumulating data confirm that the IGF-1R pathway has an important role in gynecologic cancers and in vivo and in vitro studies have shown a significant impact of IGF-1R targeted therapies in these malignancies, mainly ovarian and endometrial cancers. Currently, ongoing preclinical and clinical trials are evaluating the efficacy of IGF-1R targeting. A better understanding of the complex mechanisms underlying the regulation of the IGF system will improve the ability to develop effective treatment modalities for these malignancies.

Plasma levels of insulin-like growth factor-1 and insulin-like growth factor binding protein-3 in women with cervical neoplasia

OBJECTIVE

The goal of this study was to investigate the relationship between plasma levels of insulin-like growth factors-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) and the risk for cervical intraepithelial neoplasia (CIN) and cervical cancer.

METHODS

Plasma levels of IGF-1 and IGFBP-3 of 44 cervical cancer patients, 82 CIN patients and 40 neoplasm-free patients were investigated. Then the associations of the plasma levels of IGF-1 and IGFBP-3 with cervical neoplasm or its clinicopathologic parameters were analyzed.

RESULTS

The mean IGF-1 concentrations were significantly different among the control, CIN, and cervical cancer groups; the levels were higher in the CIN group compared to the controls. According to the quartile category, the plasma IGF-1 level was significantly higher (p=0.0015) in the CIN group than in the controls. The IGFBP-3 level showed no association between the controls and CIN groups (p=0.842). Although the mean IGF-1/IGFBP-3 molar ratio had borderline significance (p=0.08) among the study population, the quartile comparison showed a significantly higher IGF-1/IGFBP-3 molar ratio in the CIN group compared to the control group (p=0.041).

CONCLUSION

Plasma levels of IGF-1 and the IGF-1/IGFBP-3 molar ratio might be useful for the development early detection of cervical lesions and used as an adjuvant diagnostic tool for cervical neoplasia after more larger scale research.

Gonadal apoptosis during sex reversal of the rice field eel: implications for an evolutionarily conserved role of the molecular chaperone heat shock protein 10

Role of apoptosis in gonadal transformation of the rice field eel remains unknown. Here we report characterization of apoptotic pattern of testis, ovary, and ovotestis of the rice field eel, a vertebrate with natural sex reversal characteristic. DNA laddering assay showed typical ladder with step around 200 bp in the gonads, especially in testis. Terminal transferase dUTP nick end labeling on gonads indicated obvious apoptotic signals in the seminiferous tubules. Western blot analysis revealed that pro-apoptotic genes, Caspase 9 and p53, were upregulated and anti-apoptotic factor Bcl2 was downregulated in testis compared with both ovary and ovotestis. These data indicated that sex reversal process is accompanied by gonadal apoptosis with the highest proportion of cell death in the testis. Furthermore, we identified the Hsp10 by differentially screening of testis, ovary, and ovotestis using microarray technique, which is evolutionarily conserved and differentially expressed during gonadal transformation. Downregulation of Hsp10 is consistent with high apoptosis during the gonadal transformation. Flow cytometry assay confirmed that Hsp10 inhibits the apoptosis in male gonadal cells. Moreover, upregulation and mis-localization at sub-cellular level of the HSP10 together with its partner HSP60 is associated with tumorigenesis in human testis. These results suggest that downregulation of Hsp10 would be one of the main causes of apoptosis in testis, overexpression of Hsp10 suppresses apoptosis, and potentially results in testis tumorigenesis, which provide clues for understanding the mechanisms of germ cell apoptosis. Development of Hsp10 as a diagnostic marker or even treatment target will be promising in testis cancer diagnosis and therapy.

Emerging anticancer therapeutic targets and the cardiovascular system: is there cause for concern?

The race for a cure to cancer continues, fueled by unprecedented discoveries of fundamental biology underlying carcinogenesis and tumorigenesis. The expansion of the target list and tools to approach them is moving the oncology community extraordinarily rapidly to clinical trials, bringing new hope for cancer patients. This effort is also propelling biological discoveries in cardiovascular research, because many of the targets being explored in cancer play fundamental roles in the heart and vasculature. The combined efforts of cardiovascular and cancer biologists, along with clinical investigators in these fields, will be needed to understand how to safely exploit these efforts. Here, we discuss a few of the many research foci in oncology where we believe such collaboration will be particularly important.

Targeting the IGF1 axis in cancer proliferation

The IGF network of ligands, cell-surface receptors and IGF-binding proteins has important roles at multiple levels, including the cellular, organ and organism levels. The IGF system mediates growth, differentiation and developmental processes, and is also involved in various metabolic activities. Dysregulation of IGF system expression and action is linked to diverse pathologies, ranging from growth deficits to cancer development. Targeting of the IGF axis emerged in recent years as a promising therapeutic approach in conditions in which the IGF system is involved. Specific IGF1 receptor (IGF1R) targeting, in particular, produced the best experimental and clinical results so far, and generated significant optimism in the field. This review provides a basic analysis of the role of the IGF1R in cancer biology and explores the functional interactions between the IGF signaling pathways and various cancer genes (e.g., oncogenes, tumor suppressors). In addition, we review a number of specific malignancies in which the IGF system is involved and summarize recent data on preclinical and clinical studies employing IGF1R-targeted modalities.

The insulin-like growth factor-I receptor as an oncogene

The insulin-like growth factor-I receptor (IGF-IR) mediates the biological actions of both IGF-I and IGF-II. The IGF-IR is expressed in most transformed cells, where it displays potent antiapoptotic, cell-survival, and transforming activities. IGF-IR expression is a fundamental prerequisite for the acquisition of a malignant phenotype, as suggested by the finding that IGF-IR-null cells (derived from IGF-IR knock-out embryos) are unable to undergo transformation when exposed to cellular or viral oncogenes. This review article will focus on the underlying molecular mechanisms that are responsible for the normal, physiological control of IGF-IR gene expression, as well as the cellular pathways that underlie its aberrant expression in cancer. Examples from the clinics will be presented, including a description of how the IGF system is involved in breast, prostate, pediatric, and gynecological cancers. Finally, current attempts to target the IGF-IR as a therapeutic approach will be described.

Insulin-like growth factor system gene expression in cervical scrapes from women with squamous intraepithelial lesions and cervical cancer

BACKGROUND

There is ample evidence that the insulin-like growth factors (IGF) system is involved in the development of several types of cancer. The aim of this study was to evaluate the expression levels of IGF-I, IGF-II, IGF binding protein 3 (IGFBP-3) and IGF-I receptor (IGF-IR) in exfoliated cervical cells in cervical carcinogenesis.

METHODS

mRNA levels of IGF-I, IGF-II, IGFBP-3 and IGF-IR were assessed by real-time PCR in 105 cervical scrapes obtained from 16 patients diagnosed with low-grade squamous intraepithelial lesions (LSIL), 24 with high-grade SIL (HSIL), 23 with cervical cancer, and 42 from controls with normal Papanicolau (Pap) test.

RESULTS

IGF-I mRNA levels were very low and no significant differences were seen between control and other groups. IGF-II mRNA levels were significantly lower in LSIL than in control group (median [arbitrary units]: 0.38 vs. 2.42, P=0.006) but its expression in HSIL and cervical cancer was similar to the one observed in controls. IGFBP-3 mRNA levels were significantly lower in cancer than in controls (median [arbitrary units]: 0.43 vs. 0.73, P=0.03). We observed a decrease in IGF-IR gene expression as the SIL degree increased (median for controls, LSIL, HSIL, and cervical carcinoma [arbitrary units]: 31.24, 9.08, 8.95, and 3.56, respectively). IGF-IR mRNA levels were significantly lower in HSIL and cervical cancer in comparison with controls (P=0.043 and P<0.001, respectively).

CONCLUSIONS

The present observations suggest that a reduced expression of IGFBP-3 and IGF-IR can be associated with progression to cervical cancer; the specific role played by the IGF-IR in this process remains unclear.

Down-regulation of insulin-like growth factor binding protein-5 (IGFBP-5): novel marker for cervical carcinogenesis

To better understand the underlying pathways of cervical carcinogenesis, cDNA microarray analysis was performed on 2 sets of squamous cell carcinomas (SCCs) and their adjacent normal squamous epithelia. Consistently altered expression was detected for 32 genes. Real-time RT-PCR analysis was conducted on a selected subset of these genes (S100A2, GPC4, p72, IGFBP-5, TRIM2 and NAB2) for 14 additional SCCs and 10 normal epithelia. This found that, of the 6 candidate genes, only the insulin-like growth factor binding protein-5 (IGFBP-5) mRNA was generally and significantly under-expressed in SCCs (p < 0.001). All normal cervical epithelia (30 of 30) stained positively for IGFBP-5 protein, with 70% showing strong staining, whereas 65% (17/26) of SCC had complete loss of IGFBP-5, and only 8% (2/26) SCC retained strong expression (p < 0.001). Immunohistochemistry of premalignant cervical intraepithelial neoplasia (CIN) lesions shows a significantly weaker or negative staining in advanced CIN3 lesions compared with normal squamous epithelia (p = 0.001). This is the first study to show that down-regulation of IGFBP-5 protein correlates with cervical carcinogenesis and does so at a preneoplastic stage.

Insulin-like Growth Factor-I and Risk of High-Grade Cervical Intraepithelial Neoplasia

Insulin-like growth factors (IGF) and their binding proteins (IGFBP) have been implicated in the risk of several epithelial or glandular tumors, including prostate cancer, breast cancer, and colon cancer. Cervical cancer, which is also of epithelial origin, has been shown to overexpress receptors for IGF-I, and plasma levels of IGF-I have been positively associated with cervical cancer precursors in one epidemiologic study. In this case-control study, we investigated plasma levels of IGF-I and IGFBP-3 in relation to the risk of histologically confirmed high-grade cervical intraepithelial neoplasia (HGCIN) and the risk of human papillomavirus (HPV) infection. Included in this analysis were 329 cases and 621 controls recruited from clinics affiliated with two Montréal-area hospital centers. We observed a reduced risk of HGCIN for increasing levels of IGF-I, with an adjusted odds ratio (OR) of 0.40 (95% confidence interval, 0.19-0.87) for the highest quartile relative to the lowest quartile of IGF-I. No association was observed between IGFBP-3 levels and HGCIN. Among controls, IGF-I was associated with a decreased risk of being positive for HPV-16 or HPV-18, with an adjusted odds ratio of 0.20 (95% confidence interval, 0.05-0.87) for the highest quartile relative to the lowest quartile of IGF-I. There was no association observed between IGFBP-3 levels and HPV infection status. IGF-I-mediated effects seemed to predominate among women <30 years of age. In contrast to the previously reported study, our results suggest that levels of IGF-I in young women may be inversely associated with HGCIN, a precursor to cervical cancer.

Clustering of microarray data reveals transcript patterns associated with somatic embryogenesis in soybean

Globular somatic embryos can be induced from immature cotyledons of soybean (Glycine max L. Merr. cv Jack) placed on high levels of the auxin 2,4-dichlorophenoxyacetic acid (2,4-D). Somatic embryos develop from the adaxial side of the cotyledon, whereas the abaxial side evolves into a callus. Using a 9,280-cDNA clone array, we have compared steady-state RNA from the adaxial side from which embryos develop and from the abaxial callus at five time points over the course of the 4 weeks necessary for the development of globular embryos. In a second set of experiments, we have profiled the expression of each clone in the adaxial side during the same period. A total of 495 genes differentially expressed in at least one of these experiments were grouped according to the similarity of their expression profiles using a nonhierarchical clustering algorithm. Our results indicate that the appearance of somatic embryos is preceded by dedifferentiation of the cotyledon during the first 2 weeks on auxin. Changes in mRNA abundance of genes characteristic of oxidative stress and genes indicative of cell division in the adaxial side of the cotyledons suggest that the arrangement of the new cells into organized structures might depend on a genetically controlled balance between cell proliferation and cell death. Our data also suggest that the formation of somatic globular embryos is accompanied by the transcription of storage proteins and the synthesis of gibberellic acid.

The interface between ErbB and non-ErbB receptors in tumor invasion: clinical implications and opportunities for target discovery

The molecular switches by which malignant cancer cells evolve from a confined to an invasive state are poorly understood, but seem to involve a progressive activation of a signaling network shared by several growth factor receptors and non-receptor molecules. Abnormal expression of ErbB tyrosine kinase receptors, commonly seen in cancer, is an early event in the invasive process, which makes these receptors exciting targets for drug discovery. The past few years have been full of promise for ErbB targeting in the context of receptor overexpression, but also fraught with disappointment as clinical efficacy has often been hampered by potential problems such as the heterogeneity of receptor expression within the same tumor, and the extensive cooperative signaling among ErbB and non-ErbB receptors. Cooperative signaling is a common characteristic of invasive cancer cells, and is believed to dictate the genetic program that controls invasion switches. Molecular studies on the combinatorial signaling involved in tumor invasion are becoming a fertile area for target discovery in cancer. This review discusses how cooperative signaling between ErbB and non-ErbB receptors regulates tumor invasion and hence provides multiple opportunities for drug discovery, and how current therapies and investigational drugs could pave the way to even more potent alternative combinatorial therapeutic approaches for invasive cancers.

Insulin-like growth factor II in gynecological cancers: a preliminary study

PROBLEM

We have previously reported elevated serum levels of cervical human papilloma viral proteins E6 and E7 and serum insulin-like growth factor II (IGF-II) in women with cervical cancer and advanced cervical intraepithelial neoplasia. As most women with cervical cancer have elevated levels of serum IGF-II, we sought to determine whether the cervical cancer and lymph node biopsies from these women demonstrated increased production of IGF-II and whether this elevation was also present in ovarian and endometrial cancers.

METHOD OF STUDY

We used the semi-quantitative immunofluorescent antibody assay established in our laboratory to identify the levels of IGF-II in 21 cervical cancers (seven with matching lymph nodes), 18 benign cervical biopsies, 13 endometrial cancers, 15 benign endometrial biopsies, 5 ovarian cancers, and 15 benign ovarian biopsies.

RESULTS

The immunofluorescent IGF-II levels (relative intensity per pixel) were the highest in cervical cancers; they were significantly higher than in matched controls. IGF-II levels were not higher in ovarian cancers and only slightly elevated in endometrial cancers. The presence of IGF-II in pelvic lymph nodes of women with cervical cancer paralleled with those in the cervical cancers. Interestingly, we could identify small nests of metastases of malignant cells in the nodes (pauci-cellular metastasis) by using IGF-II as the marker.

CONCLUSION

We propose that measurement and identification of IGF-II in the cervical biopsy may be a sensitive method of detecting cervical cancer and metastatic spread in the lymph nodes.

IGF-1 in gynaecology and obstetrics: update 2002

Recent discoveries on endocrine, paracrine and autocrine involvement of insulin-like growth factor-1 (IGF-1) in the proliferation of many tissues raised the attention of its role in reproduction and in the growth of various cancers as well as of benign proliferations. The intention of this article is to focus on IGF-1 in the field of gynaecology. Perimenopausal women who exhibit high IGF-1 and low IGF binding protein (IGFBP) levels, like IGFBG-3, have an increased risk of developing breast cancer. A higher risk for cervical, ovarian and endometrial cancer is related to high IGF-1 levels in post- and premenopausal women. It has been shown that myomas, by far the most common benign uterine tumor in women, grow in the presence of IGF-1, in vitro as well as in vivo. Studies show that IGF-1 is involved in the differentiation of various reproductive tissues, like endometrium and ovarian tissues. Patients suffering from polycystic ovary syndrome (PCO) frequently show insulin resistance accompanied by an increase of IGF-1 in plasma. Plasma IGF-1 levels are higher in cases of severe endometriosis, however, in endometriosis and in PCO IGF levels locally in the endometrium are reduced, what might explain infertility. Recently, it was shown that IGF facilitates the implantation of the human embryo in the endometrium during IVF. Implantation is a paradox where different immune systems have to collaborate to make implantation and survival of the pregnancy possible. IGF seems to be the starter molecule so that the two epithelia can fuse. A disturbance can result in complications during pregnancy i.e. spontaneous miscarriage, preeclampsia as well as defects of the embryo. Therefore, IGF is a useful marker in successful pregnancy as well. A better mechanistic understanding of IGF-1 action on the cellular level not only provides more elegant mechanistic explanations for the scientist, but the practitioner might find it interesting to utilize its diagnostic potential as a marker for various diseases. The relation between systemic IGF levels and local tissue IGF-1 levels has not yet been determined for all conditions.

Identification of two genes differentially expressed upon different spatial configuration of the MGH-U3 human bladder cancer cells

By using mRNA differential display technology, we have compared gene expression in neoconfluent (actively proliferating) and 14-day confluent (non-proliferative) MGH-U3 cells. Two clones (6.17.6 and 10.9.2) displayed significantly increased expression in the 14-day confluent MGH-U3 cells, as confirmed by Northern blot analysis. Nucleotide sequence showed that clone 6.17.6 was part of the human insulin-like growth factor binding protein-5 (IGFBP-5) cDNA, while clone 10.9.2 was part of a human gene with unknown function (clone HSI12602). The differential IGFBP-5 expression in this model system was also evidenced by Western analysis. The possible anti-proliferative role of IGFBP-5 in this model system is briefly discussed.

Expression of components of the IGF signalling system in childhood acute lymphoblastic leukaemia

BACKGROUND

Alterations in the insulin-like growth factor (IGF) system have been reported for different tumours. They are of particular interest in the search for new prognostic and therapeutic approaches in cancer. In childhood acute lymphoblastic leukaemia (ALL) the amount of "tumour mass" at diagnosis can exceed 1 kg. To understand the endocrine, paracrine, and autocrine potential of the malignant transformed progenitor cells, the ability of these cells to express components of the IGF system needs to be investigated.

AIM

To characterise the expression pattern of genes of the IGF system in malignant lymphoblasts of children suffering from ALL.

METHODS

Reverse transcription polymerase chain reaction of Ficoll separated mononuclear cells from 142 children with ALL, 127 cord blood samples, and 55 blood samples of age matched controls were studied.

RESULTS

The expression of IGF-I, IGF-II, IGF binding protein 5 (IGFBP-5), and CTGF (IGFBP-rP2) was seen in a higher proportion of mononuclear cells of patients with ALL than in controls. Patients with ALL who were in continuous remission had a lower percentage of IGFBP-2 and IGFBP-3 expressing mononuclear cells at diagnosis than did those who developed a relapse. Only malignant lymphoblasts of B cell origin showed expression of CTGF (IGFBP-rP2). Malignant lymphoblasts of T cell origin more often expressed IGFBP-2 and IGFBP-5, whereas IGF-II and IGFBP-3 expression was seen more often in lymphoblasts of B cell origin.

CONCLUSIONS

Malignant lymphoblasts of patients with ALL express components of the IGF system and therefore promote their own growth in an autocrine, paracrine, or endocrine manner. Whether these components will be useful as prognostic factors in the stratification of ALL treatment in children needs to be evaluated.

A maize insulin-like growth factor signals to a transduction pathway that regulates protein synthesis in maize

Insulin and insulin-like growth factors (IGFs) are well-characterized regulators in higher eukaryotic cells that control biological processes such as cell growth and survival, and selective translation of mRNAs. This research presents the purification of a 20 kDa protein, isolated from maize tissue, with IGF activity. The protein was purified from 48 h-germinated maize embryonic axes by G-50 Sephadex fractionation followed by affinity chromatography through a bovine insulin antibody-Sepharose column. This protein proved to significantly speed up maize germination and seedling growth. At the molecular level, Zea mays IGF (ZmIGF) enhanced phosphorylation of S6 ribosomal protein (rp) on the 40 S ribosomal subunit, in a similar way as observed when bovine insulin is applied to maize axes during germination. Rapamycin, a specific inhibitor of the insulin-stimulated signal transduction pathway, prevented S6 rp phosphorylation in maize axes. Moreover, ZmIGF stimulated [(35)S]methionine incorporation into rps, above the level of overall cytoplasmic proteins. Either incubation with anti-insulin antibody, heat treatment (60 degrees C) or trypsin digestion abolished this ZmIGF effect. It is proposed that ZmIGF is an endogenous maize growth factor that regulates the synthesis of specific proteins through a pathway similar to that of insulin or IGFs in animal tissues.

Expression and function of EGF-related peptides and their receptors in gynecological cancer--from basic science to therapy

EGF-related peptides and their receptors play an important, but not fully understood role, both, in epithelial physiology and pathophysiology but also in human tumor carcinogenesis and tumor behavior, respectively. Overexpression of EGF-related growth factors from normal epithelium to carcinomas has been demonstrated for several human tissues such as breast, endometrium, cervix and ovary. Additionally, the differential overexpression of EGFR or erb B-2 in various malignancies has already proven to be efficacious in stratifying patients with respect to a poor prognosis. These data suggest that EGF-related growth factors, erb B receptors or signaling proteins that function either upstream or downstream from these receptors may represent novel targets for selective tumor therapy. In the future, conventional chemotherapy regimes will ultimately be wedded to more biologically-oriented therapies. One important target for these novel therapeutic approaches in solid tumors will be the EGF-related growth factors and their receptors.

Luteinizing hormone-releasing hormone (LH-RH) antagonist Cetrorelix inhibits growth of DU-145 human androgen-independent prostate carcinoma in nude mice and suppresses the levels and mRNA expression of IGF-II in tumors

In previous studies, we showed that LH-RH antagonist Cetrorelix inhibits the growth of DU-145 and PC-3 human androgen-independent prostate cancers in nude mice. To investigate the mechanisms involved, we treated male nude mice bearing xenografts of DU-145 human androgen-independent prostate cancer with Cetrorelix at a dose of 100 microg/animal subcutaneously (s.c.) once a day. Tumor growth, serum and tumor levels of IGF-I and -II as well as the mRNA expression of IGF-I and -II in tumors were evaluated. After 8 weeks of treatment, final volume and weight of DU-145 tumors in mice treated with Cetrorelix were significantly decreased compared with controls and serum IGF-1 showed a significant reduction. Therapy with Cetrorelix also reduced by 84% the levels of IGF-II in DU-145 tumor tissue compared with controls, but did not affect the concentration of IGF-I. RT-PCR analyses revealed a high expression of mRNA for IGF-II, but not for IGF-I in DU-145 tumors. Treatment with Cetrorelix decreased the expression of IGF-II mRNA by 78% (p < 0.01) as compared with controls. Our study indicates that LH-RH antagonist Cetrorelix may inhibit the growth of DU- 145 human androgen-independent prostate cancers by decreasing the production and mRNA expression of IGF-II by the tumor tissue. This also suggests that LH-RH antagonist Cetrorelix could interfere with the signal transduction pathways involving IGF-II, leading to tumor growth inhibition.

Survival factors and apoptosis

This chapter will explore the role of survival factors in suppression of apoptosis, and illustrate how survival signals play a critical role in the survival of both normal and tumor cells. Survival factors necessary for the development and maintenance of the nervous system and hemopoietic system will be surveyed. This will be followed by a detailed discussion of the role of insulin-like growth factor I (IGF-I) and its receptor in suppression of apoptosis. The importance of survival signals from the IGF-IR for development and tumorigenesis will be discussed, and results of a mutational analysis of the receptor to assign domains necessary for suppression of apoptosis will be summarized. Finally, a discussion of the signal transduction pathways involved in survival factor-signaling will review the roles played by PI-3 kinase and AKT and speculate on how activation of these kinases by survival factors might regulate the apoptotic pathway.

Do overexpressed oncoproteins cause malignant growth of cancer cells?--Studied by antisense oligonucleotides

Antisense oligonucleotides were used to demonstrate the importance of insulin-like growth factor II and alpha-fetoprotein for the growth of hepatoma cell lines. The level of insulin-like growth factor II was found to correlate positively with cell proliferative activity, whereas alpha-fetoprotein was not. We have developed an in vitro system for the screening of antisense oligonucleotides effective for inhibiting target protein production. Using this system, the effectiveness of antisense oligonucleotides can be determined even when a specific antibody or activity assay method is not available. These approaches will be useful for verifying the physiological role of other oncoproteins or proteins in living cells, and antisense oligonucleotides may be developed as new therapeutic agents.

Alterations in the growth factor signal transduction pathways and modulators of the cell cycle in endocervical cells from macaques exposed to TCDD

After more than a year had elapsed since a single oral exposure to 2 and 4 microgram 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)/kg, there was an apparent dose-related increased incidence of significant endocervical squamous metaplasia in a group of cynomolgus macaques (Scott et al., 1998). In the present experiments we investigated the mechanisms by which chemicals like TCDD could induce epithelial cell transdifferentiation in the primate endocervix. One focus of investigation was epidermal growth factor receptor (EGFR) and the key cytosolic signaling kinases, c-Src and protein tyrosine kinase (PTK), whose responses to TCDD are well characterized. A second focus was the distal kinase Erk2 that transduces the cytosolic signal into a nuclear signal, and which in combination with nuclear casein kinase II (CKII), can lead to activation of p53. Finally, we studied three key target proteins of activated p53 (wafl/p21, Cdc2 p34, and Cdk4), whose modulation could produce cell cycle effects. The studies were carried out using primary cell cultures prepared from endocervical epithelium recovered at necropsy from TCDD-treated (2 and 4 microgram TCDD/kg) and untreated macaques. There was a significant decrease in EGFR binding activity in cells from TCDD-treated animals as compared to controls. A marked increase in the protein amount of H-Ras and a significant increase in the activity of c-Src kinase, PTK, and Erk2 were found in cells from TCDD-treated animals. A significant decrease in the activity of CKII and in the protein amount of p53, wafl/p21, and Cdc2 p34 was found. On the other hand, a substantial increase in the protein amount of Cdk4 and DNA binding activity of AP-1 was found in cells from TCDD-treated animals. In vitro experiments using primary cultures of endocervical cells from untreated macaques revealed that these cells have AhR, and that c-Src protein is functionally attached to the AhR and is specifically activated upon ligand binding as judged by the following criteria. (1) A structure-activity relationship study with TCDD and three dioxin congeners revealed a rank order for their potency in activation of AhR-associated c-Src kinase from cervical cells which was identical to that of previously determined toxicity indices. (2) TCDD-induced, AhR-associated c-Src kinase activity was abolished when an AhR immunoprecipitate from cervical cells was preincubated with alpha-naphthoflavone (AhR blocker) or geldanamycin (Src kinase inhibitor) prior to the addition of TCDD. (3) The analysis of the AhR complex showed three proteins of molecular weights of 100 (AhR), 90, and 60 kDa. (4) The same protein with molecular weight 60 kDa was found when the immunoprecipitate with anti AhR-antibody was analyzed by SDS-PAGE, then transferred into nitrocellulose membrane followed by immunobloting the membrane with anti c-Src-antibody. Our data suggest that TCDD induced pathology in endocervical cells through changes in growth factor receptor signaling, other cytosolic signaling proteins, tumor suppressor proteins, and cell cycle proteins.

Retinoic acid inhibits cell growth in HPV negative cervical carcinoma cells by induction of insulin-like growth factor binding protein-5 (IGFBP-5) secretion

Retinoids have been demonstrated to inhibit epithelial cell growth and differentiation. We examined the anti-proliferative effects of retinoic acid (RA) in an HPV positive and negative cervical carcinoma cell line. Our findings indicate that HPV-negative C33A cervical carcinoma cells are more sensitive to the growth inhibitory activity of retinoic acid (RA) than are HPV-positive CaSki cervical carcinoma cells. However, conditioned medium from RA-treated C33A cells displayed strong growth inhibitory activity in both C33A and CaSki cells. Since RA has been shown to modulate the expression of insulin-like growth factor binding proteins (IGFBPs) in many cells, we examined RA regulated expression of IGFBPs in medium isolated from RA treated C33A cells. IGFBP-5 was detectable in medium from C33A cells exposed to RA, and addition of purified exogenous IGFBP-5 resulted in growth inhibition of C33A cells. These results indicate that RA exerts it's anti-neoplastic effect in HPV negative cervical carcinoma cells via the overproduction of IGFBP-5.

Insulin-like growth factor I receptor signaling in transformation by src oncogenes

R- cells, a line of mouse embryo fibroblasts with a targeted disruption of the insulin-like growth factor I (IGF-I) receptor genes, are refractory to transformation by several viral and cellular oncogenes. Using colony formation in soft agar as a measure of full transformation, we report here that R- cells can be transformed by v-src, although they still cannot be transformed by the activated c-src527 (mutation at tyrosine 527 to phenylalanine), which readily transforms mouse embryo cells with a wild-type number of IGF-I receptors (W cells). Although v-src is a more potent inducer of tyrosine phosphorylation than c-src527, the extent of phosphorylation of either insulin receptor substrate 1 or Shc, two of the major substrates of the IGF-I receptor, does not seem sufficiently different to explain the qualitative difference in soft agar growth. v-src, however, is considerably more efficient than c-src527 in its ability to tyrosyl phosphorylate, in R- cells, the focal adhesion kinase, Stat1, and p130cas. These results indicate that v-src, but not c-src527, can bypass the requirement for a functional IGF-I receptor in the full transformation of mouse embryo fibroblasts and suggest that qualitative and quantitative differences between the two oncogenes can be used to identify some of the signals relevant to the mechanism(s) of transformation.

Insulin-like growth factor II stimulates cell proliferation through the insulin receptor

R- cells are 3T3-like fibroblasts generated from mouse embryos nullizygous for a targeted disruption of the genes encoding the type 1 insulin-like growth factor (IGF) receptor (IGF1R). These cells fail to proliferate in serum-free medium supplemented with purified growth factors, in contrast to their wild-type counterparts. However, when R- cells overexpress the insulin receptor from a stably integrated plasmid, R-/IR cells, they become capable of growing in serum-free medium supplemented solely with insulin or IGF-II, but not with IGF-I. Moreover, the introduction into R-/IR cells of an additional plasmid expressing IGF-II causes these cells to proliferate in serum-free medium without growth factor supplementation. From these results, we conclude that IGF-II can stimulate cell proliferation not only through its cognate IGF1R but also through the insulin receptor.

Adrenomedullin expression in human tumor cell lines. Its potential role as an autocrine growth factor

Although adrenomedullin (AM) previously has been identified in human tumors, its role has remained elusive. Analysis by reverse transcriptase-polymerase chain reaction (RT-PCR) revealed AM mRNA in 18 of 20 human normal tissues representing major organs, and 55 of 58 (95%) malignant cell lines. Western blot and high performance liquid chromatography analysis showed immunoreactive AM species of 18, 14, and 6 kDa that are consistent with the precursor, intermediate product, and active peptide, respectively. Immunohistochemistry and in situ RT-PCR performed on paraffin-embedded tumor cell lines of various tissue origins exhibited AM cytoplasmic staining. Neutralizing monoclonal antibody to AM inhibits tumor cell growth in a concentration-dependent manner, an effect that was reversed with the addition of exogenous AM. Responding tumor cells were shown to have approximately 50,000 AM receptors per cell by Scatchard analysis with 125I-AM and expressed AM receptor mRNA by RT-PCR. Our data showed 36 of 48 (75%) tumor cell lines expressed AM receptor mRNA by RT-PCR assessment, all of them also expressed AM. In the presence of AM, cAMP levels were shown to increase in tumor cells. Our collective data demonstrate that AM and AM receptor are expressed in numerous human cancer cell lines of diverse origin and constitute a potential autocrine growth mechanism that could drive neoplastic proliferation.

Insulin-like growth factor expression in human cancer cell lines

The insulin-like growth factors (IGFs), IGF-I and IGF-II, are potent mitogens for human lung and other epithelial cancer cell lines. Previous studies in defined medium lacking added IGF or insulin suggest that an IGF-related ligand can act as an autocrine growth factor for many cancer cell lines through action via the type I IGF receptor (IGF-R). Analysis of RNA isolated from human lung and breast cancer cell lines by reverse transcription of mRNA and polymerase chain reaction reveal that IGF-I and IGF-II mRNAs were co-expressed with IGF-R in the majority of cell lines. IGF-I mRNA was detected in 11/12 small cell lung cancer cell lines (SCLC), 13/14 nonsmall cell lung cancer (NSCLC) cell lines, and 1/2 breast cancer cell lines. IGF-II mRNA was detected in 8/10 SCLC, 11/12 NSCLC cell lines, and 2/2 breast lines. All cell lines expressed IGF-R. For analysis of IGF peptide secretion, cell lines were adapted to growth in serum/hormone-free culture medium (R0), and to avoid interference by IGF-binding proteins, secreted IGF peptides were isolated under acidic conditions and analyzed by Western blotting. Based upon measurement of the sensitivity of the anti-IGF antibodies for detection of recombinant human IGFs, IGF peptides accumulated in conditioned medium at greater than picomolar concentrations should have been readily detected. In three cell lines (two lung and one breast) secreted IGF immunoreactivity was detected as three molecular mass species of 23, 14, and 6 kDa. Isolation and NH2-terminal sequencing of each of these species definitively identified them as differentially processed forms of the IGF-II prohormone. Despite the high frequency of IGF-I gene expression detected by reverse transcription-polymerase chain reaction analysis, only one lung cancer cell line, NCI-N417d, was found that unequivocally secreted IGF-I peptide. This direct sequence determination unambiguously identifies IGF-II as the predominant IGF involved in the autocrine growth stimulation of human lung and breast epithelial tumor cell lines and supports a growing body of literature that implicates IGF-II/IGF-R autocrine loops as a common growth mechanism in epithelial carcinogenesis.