Circulating levels of insulin-like growth factor-II and IGF-binding protein 3 in cervical cancer

Targeting the p53 signaling pathway in cancers: Molecular mechanisms and clinical studies

Tumor suppressor p53 can transcriptionally activate downstream genes in response to stress, and then regulate the cell cycle, DNA repair, metabolism, angiogenesis, apoptosis, and other biological responses. p53 has seven functional domains and 12 splice isoforms, and different domains and subtypes play different roles. The activation and inactivation of p53 are finely regulated and are associated with phosphorylation/acetylation modification and ubiquitination modification, respectively. Abnormal activation of p53 is closely related to the occurrence and development of cancer. While targeted therapy of the p53 signaling pathway is still in its early stages and only a few drugs or treatments have entered clinical trials, the development of new drugs and ongoing clinical trials are expected to lead to the widespread use of p53 signaling-targeted therapy in cancer treatment in the future. TRIAP1 is a novel p53 downstream inhibitor of apoptosis. TRIAP1 is the homolog of yeast mitochondrial intermembrane protein MDM35, which can play a tumor-promoting role by blocking the mitochondria-dependent apoptosis pathway. This work provides a systematic overview of recent basic research and clinical progress in the p53 signaling pathway and proposes that TRIAP1 is an important therapeutic target downstream of p53 signaling.

Characterizing the extracellular matrix transcriptome of cervical, endometrial, and uterine cancers

•

The matrisome plays a critical role in the progression of cancer, but the matrisomes of gynecological cancers have not been well characterized.

•

We built an in silico analysis pipeline to analyze publicly available bulk RNA-seq datasets of cervical, endometrial, and uterine cancers.

•

Using a machine learning approach, we identified genes and gene networks that held inferential significance for cancer stage and patient survival.

•

Cervical, endometrial, and uterine cancers are highly distinct from one another and should be analyzed separately.

Increasingly, the matrisome, a set of proteins that form the core of the extracellular matrix (ECM) or are closely associated with it, has been demonstrated to play a key role in tumor progression. However, in the context of gynecological cancers, the matrisome has not been well characterized. A holistic, yet targeted, exploration of the tumor microenvironment is critical for better understanding the progression of gynecological cancers, identifying key biomarkers for cancer progression, establishing the role of gene expression in patient survival, and for assisting in the development of new targeted therapies. In this work, we explored the matrisome gene expression profiles of cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), uterine corpus endometrial carcinoma (UCEC), and uterine carcinosarcoma (UCS) using publicly available RNA-seq data from The Cancer Genome Atlas (TCGA) and The Genotype-Tissue Expression (GTEx) portal. We hypothesized that the matrisomal expression patterns of CESC, UCEC, and UCS would be highly distinct with respect to genes which are differentially expressed and hold inferential significance with respect to tumor progression, patient survival, or both. Through a combination of statistical and machine learning analysis techniques, we identified sets of genes and gene networks which characterized each of the gynecological cancer cohorts. Our findings demonstrate that the matrisome is critical for characterizing gynecological cancers and transcriptomic mechanisms of cancer progression and outcome. Furthermore, while the goal of pan-cancer transcriptional analyses is often to highlight the shared attributes of these cancer types, we demonstrate that they are highly distinct diseases which require separate analysis, modeling, and treatment approaches. In future studies, matrisome genes and gene ontology terms that were identified as holding inferential significance for cancer stage and patient survival can be evaluated as potential drug targets and incorporated into in vitro models of disease.

A patient with solid gynecologic cancer causing lactic acidosis, severe hypercalcemia, and hypoglycemia

Though rare in cervical cancer patients, paraneoplastic syndrome usually presents with several endocrine and hormonal symptoms. Knowledge of the pathophysiology that underlies these abnormalities is beneficial to diagnosis and treatment. An interdisciplinary approach and test analysis prior to initiating specific treatment is recommended, though prognosis appears poor in advanced cases.

The IGF axis in HPV associated cancers

Human papillomaviruses (HPV) infect and replicate in stratified epithelium at cutaneous and mucosal surfaces. The proliferation and maintenance of keratinocytes, the cells which make up this epithelium, are controlled by a number of growth factor receptors such as the keratinocyte growth factor receptor (KGFR, also called fibroblast growth factor receptor 2b (FGFR2b)), the epithelial growth factor receptor (EGFR) and the insulin-like growth factor receptors 1 and 2 (IGF1R and IGF2R). In this review, we will delineate the mutation, gene transcription, translation and processing of the IGF axis within HPV associated cancers. The IGFs are key for developmental and postnatal growth of almost all tissues; we explore whether this crucial axis has been hijacked by HPV.

Insulin-Like Growth Factor I Receptor (IGF-IR) Ligands and BMI in Squamous Intra-Epithelial Lesion (SIL) of Cervix

INTRODUCTION

Cancer cervix is the most common cancer in women in developing countries like India. Several studies have linked insulin-like growth factors-I & II (IGF-I and IGF-II) and IGF binding proteins-3 (IGFBP-3) with pathogenesis of Squamous Intraepithelial Lesion of cervix (SIL). To the best of our knowledge, no study has shown any correlation between circulating C-Peptide levels and SIL.

AIM

The present study has attempted to evaluate the correlation between SIL and IGF-IR ligands (IGF-I, IGF-II, C-Peptide), IGF binding protein (IGFBP-3) and Body Mass Index (BMI).

MATERIALS AND METHODS

The present case-control study consisted of 31 histologically proven SIL cases and 31 age matched controls without evidence of SIL. A 10 ml blood sample was collected in heparinized vial. Plasma was separated immediately using centrifugation and was stored at -80(0) C till further analysis. Plasma levels of IGF-I, IGF-II, C-peptide and IGFBP3 were measured using commercially available Enzyme Linked Immunosorbent Assay (ELISA) kit. Height and weight was noted for calculation of BMI. Bio-effective molar ratio (BEMR) was calculated as 3.72 x {(0.25 x IGF-I) + (0.032 x IGF-II) + (0.0025 x C-peptide)} / {(1435 + IGFBP-3) - (2.79 x IGF-I) - (2.87 x IGF-II)}. Statistical analysis was performed using SPSS and Microsoft Excel software employing student t-test, Mann-Whitney and Chi-square test for trend while binary logistic regression was used to estimate the odds ratios (OR) and corresponding 95% Confidence Intervals (CI).

RESULT

IGF-I, IGF-II levels and BEMR were significantly increased in SIL compared to controls (p= 0.001, p <0.001, and p <0.001, respectively). C-Peptide levels were higher in controls than SIL (p = 0.04). IGFBP-3 & BMI in SIL were not significantly related when compared with controls. Risk of SIL in 4(th) quartile for BEMR, IGF-I, and IGF-II was 12.18(95% CI= 3.13-47.39), 3.94(95% CI = 1.24-12.56), and 4.57(95% CI = 1.42-14.7), respectively.

CONCLUSION

Elevated levels of IGF-I and IGF-II are associated with risk of SIL while BEMR emerges out to be a derived factor strongly associated with risk of SIL.

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.

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.

Mouse 3T3 fibroblasts under the influence of fibroblasts isolated from stroma of human basal cell carcinoma acquire properties of multipotent stem cells

BACKGROUND INFORMATION

Multipotent mesenchymal stem cells can participate in the formation of a microenvironment stimulating the aggressive behaviour of cancer cells. Moreover, cells exhibiting pluripotent ESC (embryonic stem cell) markers (Nanog and Oct4) have been observed in many tumours. Here, we investigate the role of cancer-associated fibroblasts in the formation of stem cell supporting properties of tumour stroma. We test the influence of fibroblasts isolated from basal cell carcinoma on mouse 3T3 fibroblasts, focusing on the expression of stem cell markers and plasticity in vitro by means of microarrays, qRT-PCR (quantitative real-time PCR) and immunohistochemistry.

RESULTS

We demonstrate the biological activity of the cancer stromal fibroblasts by influencing the 3T3 fibroblasts to express markers such as Oct4, Nanog and Sox2 and to show differentiation potential similar to mesenchymal stem cells. The role of growth factors such as IGF2 (insulin-like growth factor 2), FGF7 (fibroblast growth factor 7), LEP (leptin), NGF (nerve growth factor) and TGFβ (transforming growth factor β), produced by the stromal fibroblasts, is established to participate in their bioactivity. Uninduced 3T3 do not express the stem cell markers and show minimal differentiation potential.

CONCLUSIONS

Our observations indicate the pro-stem cell activity of cancer-associated fibroblasts and underline the role of epithelial-mesenchymal interaction in tumour biology.

Levels of insulin-like growth factor during pregnancy and maternal cancer risk: a nested case-control study

Previous studies have suggested that pregnancy measures of insulin-like growth factors (IGFs) may be related to breast cancer risk in mothers. IGFs may also be important in cervical cancer etiology. We conducted a nested case-control study (69 breast cancer cases, 151 cervical cancer cases, 443 controls) among mothers of the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Over 70% of blood samples was taken prior to 15 weeks' gestation; the remainder before 30 weeks. Logistic regression, controlling for maternal age, gestational age, and sample type (plasma/serum) was used to model the association between IGFs and maternal cancer risk. Neither IGF-I nor IGF-II were associated with breast or cervical cancer. IGF-binding protein (BP)-3 was not related to breast cancer, but there was a suggestion that women in the highest compared to lowest quartile of IGFBP-3 had reduced risk of cervical cancer, OR 0.43 (95% CI 0.21-0.86). In conclusion, the importance of IGFs measured in pregnancy and later breast and cervical cancer remains unclear, though IGFBP-3 may be a marker of lowered risk.

Plasma insulin-like growth factor-binding protein-2 levels as diagnostic and prognostic biomarker of colorectal cancer

CONTEXT

Overexpression of IGF-II and IGF-binding protein (IGFBP)-2 has been reported in several cancers.

OBJECTIVE

We aimed to assess the roles of plasma IGF-II and IGFBP-2 levels as diagnostic and prognostic biomarkers and the impact of loss of imprinting (LOI) of IGF-II on the survival of colorectal cancer (CRC).

DESIGN

We conducted a case control and prospective cohort study for diagnostic and prognostic values, respectively.

PATIENTS AND SETTING

Plasma levels of IGF-II and IGFBP-2 were measured in 162 patients with CRC before surgery, in paired 15 patients after curative surgery, in 24 patients with advanced colon polyps, and in 114 healthy controls between 2003 and 2006 in National Taiwan University Hospital.

RESULTS

The area under the curve values of using IGFBP-2 as a diagnostic marker for advanced colon polyp and CRC were 0.654 [95% confidence interval (CI) = 0.547-0.76; P = 0.017] and 0.815 (95% CI = 0.766-0.864; P < 0.001), respectively. The sensitivity and specificity for diagnosing CRC were 80.2 and 64%, respectively, if the cutoff value of IGFBP-2 was 377 ng/ml. In the multivariate Cox proportional hazards regression model, higher IGFBP-2 levels were associated with increased risk of mortality [hazard ratio (HR) = 2.46; P = 0.017], whereas higher IGF-II levels were associated with reduced risk of mortality (HR = 0.42; P = 0.044). LOI of IGF-II was associated with increased risk of mortality (HR = 7.91; P = 0.014) in patients with stage IV disease.

CONCLUSIONS

IGFBP-2 is a potential diagnostic and prognostic biomarker of CRC. LOI of IGF-II is significantly associated with poor prognosis in patients with stage IV disease.

Head and neck squamous cancer stromal fibroblasts produce growth factors influencing phenotype of normal human keratinocytes

Epithelial-mesenchymal interaction between stromal fibroblasts and cancer cells influences the functional properties of tumor epithelium, including the tumor progression and spread. We compared fibroblasts prepared from stroma of squamous cell carcinoma and normal dermal fibroblasts concerning their biological activity toward normal keratinocytes assessed by immunocytochemistry and profiling of gene activation for growth factors/cytokines by microarray chip technology. IGF-2 and BMP-4 were determined as candidate factors responsible for tumor-associated fibroblast activity that influences normal epithelia. This effect was confirmed by addition of recombinant IGF-2 and BMP4, respectively, to the culture medium. This hypothesis was also verified by inhibition experiments where blocking antibodies were employed in the medium conditioned by cancer-associated fibroblast. Presence of these growth factors was also detected in tumor samples.

Clinical implications of insulin-like growth factor 1 system in early-stage cervical cancer

This study was aimed to identify the expression and the correlation of insulin-like growth factor-1 (IGF-1) system and their prognostic impacts in cervical cancer. Seventy-two patients with early-stage cervical cancer were eligible. We obtained the serum levels of total IGF-1 and IGF binding protein-3 (IGFBP-3) by enzyme-linked immunosorbent assay and the expression of IGF-1 receptor (IGF-1R) in cancerous tissue by immuno-fluorescent (IF) stains. The 5-year recurrence-free and overall survival rates were significantly lower (P=0.003 and P=0.01, respectively) among patients with high-grade expression of tissue IGF-1R, compared with those with low-grade expression. After adjustment for other factors, preoperative serum total IGF-1 or IGFBP-3 levels failed to predict cancer death and recurrence. High-grade expression of IGF-1R and elevated preoperative squamous cell carcinoma antigen level were independent predictors of both death and recurrence, and combination of both factors could further help identify the subgroup of patients at higher death risk. The IF staining indicates the colocalisation of IGF-1 and IGF-1R in the cancerous tissues, whereas the IGF-1R expression is not correlated with circulating levels of IGF-1 or IGFBP-3. In early-stage cervical cancer, IGF-1 system may have a paracrine or autocrine function and the adverse impacts on prognosis by IGF-1R overexpression are implicated.

Molecular biology of cervical cancer

Cervical cancer is a virus-induced disease that is caused by the integration of high-risk infecting human papillomaviruses (HPV) in the host genome. For this reason, the carcinogenesis process of cervical cancer is associated to the expression of the viral oncogenic proteins E6 and E7. These proteins are capable of inactivating p53 and pRb, which induces a continuous cell proliferation with the increasing risk of accumulation of DNA damage that eventually leads to cancer. Moreover, cervical cancer can be prevented by prophylactic HPV vaccines; their molecular characteristics and mechanism of action are reviewed. Ultimately, new molecular targets for cervical cancer like proteasome, the EGFR family and IGF family are exposed.

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.

Serum vascular endothelial growth factor C (VEGF-C) as a specific biomarker for advanced cervical cancer: Relationship to insulin-like growth factor II (IGF-II), IGF binding protein 3 (IGF-BP3) and VEGF-A [corrected]

OBJECTIVES

An early non-invasive diagnosis of cervical cancer and its metastasis can save lives. We have shown that serum IGF-II levels can be effectively used for a specific early diagnosis of cervical cancer. Here, we shall determine if serum levels of vascular endothelial growth factors B and C (VEGF-A [corrected] VEGF-C) associated with vasculogenic and lymphogenic metastasis may be used for an early diagnosis of advanced metastatic cervical cancer and compare these levels with those of the serum IGF-II and IGF-binding protein 3 (IGF-BP3).

MATERIAL AND METHODS

(a) Serum levels of IGF-II, IGF-BP3, VEGF-A [corrected] (VEGF(165)) and VEGF-C (ELISA kits) were determined in: 82 controls with normal Pap smears; 29 women with atypical squamous cells of undetermined significance (ASCUS) and normal cervical biopsy; 46 ASCUS and cervical intraepithelial neoplasia (CIN) on biopsy; 8 pre-therapy CIN-I; 23 successfully treated CIN-I; 75 persistent CIN-I; 14 CIN-II/III pre-therapy; 14 successfully treated CIN-II/III; 70 persistent CIN-II/III; 86 pre-therapy cervical cancer; 26 in early grades of cervical cancer; 21 in late grades of cervical cancer; 22 cervical cancer patients in remission; 50 persistent cervical cancer; 18 with ovarian cancer; and 57 with endometrial cancer. (b) Serial serum samples collected over 5 years in 5 women with progressing cervical cancer were also tested. (c) Serum and tissue VEGF-C were enumerated in 20 matched serum (ELISA) and tissue (semi-quantitative immunofluorescent antibody assay) samples from controls, early cervical cancer, late cervical cancer, ovarian cancer and endometrial cancer patients. Student's t test, chi-square analysis and linear regression analysis were used.

RESULTS

(a) As anticipated, serum IGF-II levels were elevated as early as ASCUS with CIN on biopsy and continued to be elevated in CIN (all grades; pre-therapy and persistent) and cervical cancer (pre-therapy, early, late and persistent). Serum IGF-II levels were normal in ASCUS with normal biopsy, successfully treated CIN-I, II/III, cervical cancer as well as pre-therapy ovarian and endometrial cancers (therapy efficacy: P < 0.0001 by chi-square analysis). Serum IGF-BP3 showed a significant decrease with advancing disease. Serum VEGF-A [corrected] levels were the highest in pre-therapy, early, advanced and persistent cervical cancer, as well as in ovarian and endometrial cancers. Serum VEGF-C levels, on the other hand, were the highest in late and persistent cervical cancers, but not in ovarian or endometrial cancers. (b) In the 5 women with serial samples, the serum levels of the growth factors showed similar trends. (c) VEGF-C levels in serum and tissue were elevated in cervical cancers especially in advanced grades, while they were normal in serum and tissue from the controls and women with ovarian and endometrial cancers. There was a highly significant positive correlation between VEGF-C and IGF-II and a negative correlation between IGF-BP3 and VEGF-C (P < 0.0001).

CONCLUSION

Serum IGF-II up-regulation is specific to cervical cancer and helps in the early diagnosis of malignant proliferation, while serum VEGF-C up-regulation appears to be a unique marker for an early diagnosis of cervical cancer metastasis. VEGF-C and IGF-II systems appear to be interrelated in cervical cancer, contributing to the early malignant cell proliferation and lympho-vascular metastasis. Serum IGF-BP3 and VEGF-A [corrected] appear to be common markers for all gynecological cancers.

Clinical potential of inhibitors of survival pathways and activators of apoptotic pathways in treatment of cervical cancer: changing the apoptotic balance

Cervical cancer is the most common gynaecological malignant disorder worldwide. The best possible treatment of locally advanced cervical cancer is a combination of radiation and cisplatin-based chemotherapy. However, 5-year overall survival is still only 52%. To improve treatment results, research should focus on the discovery of innovative drug strategies. Drugs directed at inducing tumour-cell apoptosis are regarded as important treatment modalities. Here, we present an overview of the molecular options that can change the apoptotic balance in cervical cancer, through increasing death-receptor-mediated apoptosis, the use of proteasome inhibitors, short interfering RNAs, or non-steroidal anti-inflammatory drugs (NSAIDs). Furthermore, the potential of attacking prosurvival signalling through the epidermal-growth-factor receptor and insulin-like-growth-factor receptor to support the apoptotic process is discussed. Additional research is needed to elucidate the clinical potential of these compounds in the treatment of cervical cancer.

Up-regulation of vascular endothelial growth factor-C by nicotine in cervical cancer cell lines

PROBLEM

Smoking and infection with human papilloma virus (HPV) are major risk factors for cervical cancer. Our earlier work shows that nicotine enhances cellular proliferation of cervical cancer cell lines by up-regulating epidermal growth factor (EGF) and its receptor EGF-R, which leads to increased insulin-like growth factor II in vitro. We found that the vascular endothelial growth factor (VEGF)-C, one of the five isoforms of VEGF, may be specifically involved in lymphogenic metastasis of cervical cancer. This has prompted us to study if in vitro nicotine treatment will up-regulate VEGF-C alongside EGF-R levels, while down regulating the anti-proliferative transforming growth factor (TGF)-beta levels in HPV positive cervical cancer cell lines.

METHOD OF STUDY

Cervical cancer cell lines CaSki, HeLa and ME-180, were cultured in serum free DMEM medium for 24-hr, and treated with 10 ng/mL nicotine in the medium supplemented with 10% fetal bovine serum. A group of untreated cells served as controls. The cells were cultured in chamber slides (for immunofluorescent antibody assay) as well as microtiter plate wells (for BrdU cell proliferation assay). The cellular levels of VEGF-C, TGF-beta, EGF-R and HPV-E6 (early protein 6) were measured by a semi-quantitative immunofluorescent antibody assay. The cell proliferation and immunofluorescent assay data were analyzed by a Student's t-test.

RESULTS

Cell proliferation was significantly increased after nicotine treatment in all the cell lines. The VEGF-C levels were significantly increased, while TGF-beta levels were decreased by nicotine in all the cell lines (P < 0.00001). EGF-R levels were also significantly increased after nicotine treatment in HeLa and ME-180, while HPV-E6 levels remained unchanged in all three.

CONCLUSIONS

Nicotine up regulates expression of cell proliferative VEGF-C and EGF-R, while down-regulating anti-proliferative TGF-beta. Our data suggest that nicotine in circulation and in cervical squamous epithelial cells may promote not only rapid tumor growth but its lympho-angiogenic spread (VEGF-C) as well. It appears that nicotine does not promote HPV spread in the cervical cancer cells.

Vascular endothelial growth factor (VEGF) up-regulates epidermal growth factor receptor (EGF-R) in cervical cancer in vitro: this action is mediated through HPV-E6 in HPV-positive cancers

OBJECTIVES

Epidermal Growth Factor Receptor (EGF-R) up-regulation in cervical cancer cells leads to an increase in cell proliferative Insulin-like Growth Factor II (IGF-II) and Vascular Endothelial Growth Factor (VEGF) and a decrease of the anti-proliferative IGF-binding protein-3 (IGF-BP3). The objectives for this study are: (a) to find if VEGF, in turn, up-regulates EGF-R and down-regulates IGF-BP3; (b) to determine if human papilloma virus (HPV-E6) mediates this action of VEGF in HPV-positive cells; and (c) to verify if these effects are reflected in changes in cell proliferation

METHODS

We used HPV-positive HeLa (Black), ME-180 and CaSki (Caucasian) and HPV-negative HT-3 (Caucasian) cell lines. (a) Levels of HPV-E6 in the HPV-positive cells were enumerated after treating the cells for 24 h with 20 ng/ml of VEGF using our semi-quantitative immunofluorescent antibody assay. (b) Cellular levels of EGF-R, HPV-E6, IGF-II and IGF-BP3 were enumerated in ME-180 and CaSki cells incubated for 24 h with 5, 10 and 20 ng/ml of VEGF. (c) HPV-negative HT-3 and HPV-positive ME-180 and CaSki cells were incubated with 20 ng/ml VEGF alone or in combination with antibodies to HPV-E6 and EGF-R. HPV-E6 (measured only in HPV-positive cells), EGF-R, IGF-II and IGF-BP3 levels were measured. (d) Cell proliferation was determined using cell proliferation Bradykinine-U colorimetric assay, in HT-3, HeLa and ME-180 cell lines in the presence of VEGF alone and with HPV-E6 antibodies.

RESULTS

(a) In all the HPV-positive cell lines, 20 ng/ml VEGF significantly increased (30-50%; P < 0.0001) the HPV-E6. (b) In the ME-180 and CaSki cells, VEGF treatment up-regulated EGF-R, IGF-II and HPV-E6 and down-regulated IGF-BP3 in a dose-dependent manner (P < 0.001). (c) These effects of VEGF were eliminated when the HPV-positive cells were co-incubated with antibodies to HPV-E6 or EGF-R. In the HPV-negative HT-3 cells, VEGF decreased IGF-BP3 while increasing EGF-R and IGF-II levels. Antibodies to EGF-R eliminated these effects (P < 0.0001). (d) Treatment with VEGF resulted in increased cell proliferation in HT-3, HeLa and ME-180 cells; co-incubation with HPV-E6 antibodies abrogated this effect only in the HPV-positive cells.

CONCLUSIONS

In cervical cancer, VEGF up-regulates EGF-R and down-regulates IGF-BP3, thus amplifying the cell proliferative activity of EGF-R. This action of VEGF seems to be mediated, directly through EGF-R or indirectly through HPV-E6 in the HPV-positive cancers, while EGF-R up-regulation appears to play a major role in the HPV-negative cervical cancers.

In vitro downregulation of growth factors by insulin-like growth factor binding protein-3 in cervical cancer☆

OBJECTIVES

Our hypothesis is that insulin-like growth factor binding protein 3 (IGF-BP3) would downregulate epidermal growth factor receptor (EGF-R) levels in cervical cancer cell lines, thereby reducing cellular IGF-II and angiogenesis-related vascular endothelial cell growth factor (VEGF). As folate deficiency is a risk factor in cervical cancer, we sought to determine if folic acid treatment might increase IGF-BP3 production, thereby inhibiting malignant cell proliferation.

METHODS

We determined the cellular levels of EGF-R, IGF-II, and VEGF in the cervical cancer cell lines HeLa, ME-180 (both positive for human papilloma virus; HPV), and HT-3 (HPV-negative), following their treatment with IGF-BP3. Levels of IGF-BP3 in these cells before and after treatment with folic acid and VEGF were also enumerated, using a computerized semiquantitative immunofluorescent antibody assay.

RESULTS

Treatment with IGF-BP3 significantly reduced the levels (mean intensity per pixel) of EGF-R, IGF-II, and VEGF in all three cell lines and IGF-I receptor (IGF-IR) in representative ME-180 cell line. Treatment with antiproliferative folic acid increased IGF-BP3 levels while the proliferative VEGF depleted cellular IGF-BP3 in all the cell lines.

CONCLUSIONS

Levels of EGF-R, IGF-II, IGF-IR, and VEGF are significantly reduced following treatment with IGF-BP3 in cervical cancer. We observed increased levels of IGF-BP3 by folic acid, and decreased IGF-BP3 levels by VEGF. Downregulation of EGF-R by IGF-BP3 suggests an IGF-independent action. Folate deficiency is a risk factor in cervical cancer. Our results suggest that folic acid supplementation can lead to inhibition of cervical cancer cell growth by promoting increased IGF-BP3 levels.