In vitro downregulation of growth factors by insulin-like growth factor 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.

Prognostic value of insulin-like growth factor 2 mRNA-binding protein 3 and vascular endothelial growth factor-A in patients with primary non-small-cell lung cancer

Insulin-like growth factor 2 mRNA-binding protein 3 (IMP3) and vascular endothelial growth factor-A (VEGF-A) may play important roles in the process of tumor progression and tumor angiogenesis. The aim of the present study was to examine the co-expression of IMP3 and VEGF-A in primary human non-small cell lung cancer (NSCLC), to investigate the association between these two expression levels and determine the clinicopathological implications, including changes to microvessel density (MVD), and to assess the prognostic value of co-expression. Using immunohistochemical staining, the expression of IMP3, VEGF-A and CD34 expression was detected in 128 primary NSCLC tissue samples. According to the expression of IMP3 and VEGF-A, the cases were divided into four groups. Next, the clinicopathological features, MVD and survival time were investigated across the different groups. The immunohistochemical analyses demonstrated that there was a significant correlation between IMP3 and VEGF-A expression in NSCLC (r=0.181; P=0.041). Co-expression of IMP3 and VEGF-A was significantly associated with larger primary tumor size (P=0.016), poorer differentiation (P=0.014), more advanced Tumor-Node-Metastasis stage (P=0.012), increased MVD (P=0.004) and positive lymph node metastasis (P=0.002). Survival analysis demonstrated that cases with IMP3 and VEGF-A double-positive staining were significantly associated with lower survival rates compared with cases with double-negative staining (P=0.039). In the early NSCLC (I–IIa) subgroup, the mean survival time of the double-positive staining group was significantly shorter compared with that of the double-negative staining group (P=0.015). Co-expression of IMP3 and VEGF-A was associated with angiogenesis and a poorer prognosis in NSCLC, and may therefore play a critical role in NSCLC progression.

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.

Chronic activation of vasopressin V2 receptor signalling lowers renal medullary oxygen levels in rats

AIM

In the present study, we aimed to elucidate the effects of chronic vasopressin administration on renal medullary oxygen levels.

METHODS

Adult Sprague Dawley or vasopressin-deficient Brattleboro rats were treated with the vasopressin V2 receptor agonist, desmopressin (5 ng/h; 3d), or its vehicle via osmotic minipumps. Immunostaining for pimonidazole and the transcription factor HIF-1α (hypoxia-inducible factor-1α) were used to identify hypoxic areas. Activation of HIF-target gene expression following desmopressin treatment was studied by microarray analysis.

RESULTS

Pimonidazole staining was detected in the outer and inner medulla of desmopressin-treated rats, whereas staining in control animals was weak or absent. HIF-1α immunostaining demonstrated nuclear accumulation in the papilla of desmopressin-treated animals, whereas no staining was observed in the controls. Gene expression analysis revealed significant enrichment of HIF-target genes in the group of desmopressin-regulated gene products (P = 2.6*10(-21) ). Regulated products included insulin-like growth factor binding proteins 1 and 3, angiopoietin 2, fibronectin, cathepsin D, hexokinase 2 and cyclooxygenase 2.

CONCLUSION

Our results demonstrate that an activation of the renal urine concentrating mechanism by desmopressin causes renal medullary hypoxia and an upregulation of hypoxia-inducible gene expression.

IGF-1R/MDM2 relationship confers enhanced sensitivity to RITA in Ewing sarcoma cells

Ewing sarcoma is one of the most frequent bone cancers in adolescence. Although multidisciplinary therapy has improved the survival rate for localized tumors, a critical step is the development of new drugs to improve the long-term outcome of recurrent and metastatic disease and to reduce side effects of conventional therapy. Here, we show that the small molecule reactivation of p53 and induction of tumor cell apoptosis (RITA, NSC652287) is highly effective in reducing growth and tumorigenic potential of Ewing sarcoma cell lines. These effects occur both in the presence of wt-p53 as well as of mutant or truncated forms of p53, or in its absence, suggesting the presence of additional targets in this tumor histotype. Further experiments provided evidence that RITA modulates an important oncogenic mark of these cell lines, insulin-like growth factor receptor 1 (IGF-1R). Particularly, RITA causes downregulation of IGF-1R protein levels. MDM2 degradative activity is involved in this phenomenon. Indeed, inhibition of MDM2 function by genetic or pharmacologic approaches reduces RITA sensitivity of Ewing sarcoma cell lines. Overall, these data suggest that in the cell context of Ewing sarcoma, RITA may adopt additional mechanism of action besides targeting p53, expanding its field of application. Noteworthy, these results envisage the promising utilization of RITA or its derivative as a potential treatment for Ewing sarcomas.

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.

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.

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.