Insulin-like growth factor binding proteins and breast cancer

A Facile Strategy for the Fabrication of Cell-laden Porous Alginate Hydrogels Based on Two-phase Aqueous Emulsions

Porous alginate hydrogels possess many advantages as cell carriers. However, current pore generation methods require either complex or harsh fabrication processes, toxic components, or extra purification steps, limiting the feasibility and affecting the cellular survival and function. In this study, a simple and cell-friendly approach to generate highly porous cell-laden alginate hydrogels based on two-phase aqueous emulsions is reported. The pre-gel solutions, which contain two immiscible aqueous phases of alginate and caseinate, are crosslinked by calcium ions. The porous structure of the hydrogel construct is formed by subsequently removing the caseinate phase from the ion-crosslinked alginate hydrogel. Those porous alginate hydrogels possess heterogeneous pores around 100 μm and interconnected paths. Human white adipose progenitors (WAPs) encapsulated in these hydrogels self-organize into spheroids and show enhanced viability, proliferation, and adipogenic differentiation, compared to non-porous constructs. As a proof of concept, this porous alginate hydrogel platform is employed to prepare core-shell spheres for coculture of WAPs and colon cancer cells, with WAP clusters distributed around cancer cell aggregates, to investigate cellular crosstalk. This efficacious approach is believed to provide a robust and versatile platform for engineering porous-structured alginate hydrogels for applications as cell carriers and in disease modeling.

Plant-Based Diet and IGF-1 Modulation on HER2-Positive Breast Cancer: A Lifestyle Medicine Nutrition Approach in Oncology

Breast cancer is the second most common type of cancer in women worldwide, where nutritional intervention should be part of a multidisciplinary lifestyle approach in oncology, promoting therapeutic success. Insulin-like growth factor 1 (IGF-1), along with estrogen, can promote the development of neoplastic cells in breast tissue. Cancers that develop under IGF-1 stimulation are often resistant to therapy. This case report describes a 47-year-old woman, body mass index 27.4 kg/m2, with HER2-positive breast cancer, as well as elevated blood glucose, total cholesterol, and low-density lipoprotein cholesterol. Soon after her breast cancer diagnosis, she transitioned from a Western pattern diet (WPD) to a predominantly whole-food, plant-based diet (PWFPBD) for 1035 days, followed by 232 days of PWFPBD plus night fasting for 16 hours per day. IGF-1 decreased 22.38%, glycemia and total cholesterol decreased by -55.06% and -36.00% at the end of the first intervention and went up by 6.25%, and 3.87%, respectively, at the end of the second intervention. A PWFPBD, with or without 16-hour overnight fasting, seems to modulate plasma levels of IGF-1 on a 47-year-old woman diagnosed with breast cancer, type HER2-positive. Future research, should explore the physiologic and pathophysiological mechanisms and clarify whether this dietary strategy, may be clinically useful in preventing HER2-positive breast cancer.

Insulin Growth Factor Binding Protein 7 (IGFBP7)-Related Cancer and IGFBP3 and IGFBP7 Crosstalk

The insulin/insulin-like growth factors (IGFs) have crucial tasks in the growth, differentiation, and proliferation of healthy and pernicious cells. They are involved in coordinated complexes, including receptors, ligands, binding proteins, and proteases. However, the systems can become dysregulated in tumorigenesis. Insulin-like growth factor-binding protein 7 (IGFBP7) is a protein belonging to the IGFBP superfamily (also termed GFBP-related proteins). Numerous studies have provided evidence that IGFBP3 and IGFBP7 are involved in a variety of cancers, including hepatocellular carcinoma (HCC), breast cancer, gastroesophageal cancer, colon cancer, prostate cancer, among many others. Still, very few suggest an interaction between these two molecules. In studying several cancer types in our laboratories, we found that both proteins share some crucial signaling pathways. The objective of this review is to present a comprehensive overview of the relationship between IGFBP7 and cancer, as well as highlighting IGFBP3 crosstalk with IGFBP7 reported in recent studies.

Comparison of telomere length and insulin-like growth factor-binding protein 7 promoter methylation between breast cancer tissues and adjacent normal tissues in Turkish women

BACKGROUND

Both insulin-like growth factor-binding protein 7 (IGFBP7) and telomere length (TL) are associated with proliferation and senescence of human breast cancer. This study assessed the clinical significance of both TL and IGFBP7 methylation status in breast cancer tissues compared with adjacent normal tissues. We also investigated whether IGFBP7 methylation status could be affecting TL.

METHODS

Telomere length was measured by quantitative PCR to compare tumors with their adjacent normal tissues. The IGFBP7 promoter methylation status was evaluated by methylation-specific PCR and its expression levels were determined by western blotting.

RESULTS

Telomeres were shorter in tumor tissues compared to controls (P<.0001). The mean TL was higher in breast cancer with invasive ductal carcinoma (IDC; n=72; P=.014) compared with other histological type (n=29), and TL in IDC with HER2 negative (n=53; P=.017) was higher than TL in IDC with HER2 positive (n=19). However, telomeres were shortened in advanced stages and growing tumors. IGFBP7 methylation was observed in 90% of tumor tissues and 59% of controls (P=.0002). Its frequency was significantly higher in IDC compared with invasive mixed carcinoma (IMC; P=.002) and it was not correlated either with protein expression or the other clinicopathological parameters.

CONCLUSION

These results suggest that IGFBP7 promoter methylation and shorter TL in tumor compared with adjacent tissues may be predictive biomarkers for breast cancer. Telomere maintenance may be indicative of IDC and IDC with HER2 (-) of breast cancer. Further studies with larger number of cases are necessary to verify this association.

Stromal EGF and igf-I together modulate plasticity of disseminated triple-negative breast tumors

The causes for malignant progression of disseminated tumors and the reasons recurrence rates differ in women with different breast cancer subtypes are unknown. Here, we report novel mechanisms of tumor plasticity that are mandated by microenvironmental factors and show that recurrence rates are not strictly due to cell-intrinsic properties. Specifically, outgrowth of the same population of incipient tumors is accelerated in mice with triple-negative breast cancer (TNBC) relative to those with luminal breast cancer. Systemic signals provided by overt TNBCs cause the formation of a tumor-supportive microenvironment enriched for EGF and insulin-like growth factor-I (IGF-I) at distant indolent tumor sites. Bioavailability of EGF and IGF-I enhances the expression of transcription factors associated with pluripotency, proliferation, and epithelial-mesenchymal transition. Combinatorial therapy with EGF receptor and IGF-I receptor inhibitors prevents malignant progression. These results suggest that plasticity and recurrence rates can be dictated by host systemic factors and offer novel therapeutic potential for patients with TNBC.

Insulin-like growth factor binding protein-4 and -5 modulate ligand-dependent estrogen receptor-α activation in breast cancer cells in an IGF-independent manner

Insulin-like growth factor binding proteins (IGFBPs) are modulators of numerous cellular processes including cell proliferation. Although IGFBPs classically act by sequestration of extracellular insulin-like growth factors (IGFs), thereby contributing to the fine-tuning of growth factor signals, IGF-independent actions of IGFBPs have also been described. In the breast, growth factor signaling in association with estradiol (E2)-stimulated estrogen receptor function is organized in a complex cross-talk. The importance of phosphatidylinositol 3-kinase/protein kinase B (Akt/PKB) pathway components for the E2-induced activation of estrogen receptor-alpha (ERα) is well accepted. Here we show that in the absence of IGFs, IGFBP-4 or IGFBP-5, either overexpressed in MCF-7 breast cancer cells or added exogenously, decreased the capability of E2 to induce ERα transcriptional activity. In addition, overexpression or addition of recombinant IGFBP-4 or IGFBP-5 resulted in reduction of E2-induced phosphorylation of Akt/PKB, GSK-3α/β and ERα in MCF-7 cells. The activation of the Akt/PKB-pathway describes a non-genomic effect of E2, which did not involve activation/phosphorylation of the IGF-I receptor (IGF-IR). Furthermore, knockdown of the IGF-IR did not affect the inhibition of E2-induced ERα phosphorylation by IGFBP-4 and 5. Moreover, IGFBP-4 and IGFBP-5 strongly decreased E2-triggered growth of MCF-7 cells. Our data suggest that IGFBPs interfere with the E2-induced activation of the Akt/PKB-pathway and prevent full hormone-dependent activation of ERα and breast cancer cell growth in an IGF- and IGF-IR-independent manner.

IGFBP-rP1 induces p21 expression through a p53-independent pathway, leading to cellular senescence of MCF-7 breast cancer cells

OBJECTIVES

Insulin-like growth factor-binding protein (IGFBP)-related protein 1 (IGFBP-rP1), a member of the IGFBP super family, was identified as a potent tumor suppressor in several carcinomas. IGFBP-rP1 was down-regulated in primary breast cancer tissues and several breast cancer cell lines but overexpressed in senescent human mammary epithelial cells (HMECs), suggesting that IGFBP-rP1 might be a tumor suppressor in breast cancer and the tumor suppressor role of IGFBP-rP1 might be associated with cellular senescence. The aim of the study was to observe the effect of IGFBP-rP1 on cellular senescence and the molecular events mediating this biological effect in MCF-7 breast cancer cells.

METHODS

DNA fragment-encoding IGFBP-rP1 was cloned in-frame N-terminally to EGFP gene to generate IGFBP-rP1-EGFP fusion protein expression plasmid (pEGFP-IGFBP-rP1). The plasmid pEGFP-IGFBP-rP1 was then transfected into MCF-7 cells, and the proliferation, cell cycle distribution, cellular senescence, and cell cycle-related protein expression of MCF-7 cells were examined by trypan blue exclusion, flow cytometry, senescence-associated galactosidase (SA-β-gal) staining, and Western blot analysis, respectively. Two shRNA plasmid vectors against p21 or p53 gene were constructed and stably transfected into the MCF-7 cells to determine the involvement of p21 or p53 in cellular senescence induced by IGFBP-rP1.

RESULTS

Transfection of IGFBP-rP1 or addition of condition medium (CM) from IGFBP-rP1-transfected cells in MCF-7 cells caused induction of a variety of senescent phenotypes, such as decrease in cell proliferation, increase in G0/G1 cell cycle arrest cells, change in cell morphology, and increase in senescence-associated galactosidase (SA-β-gal) activity. IGFBP-rP1-induced growth arrest is associated with enhanced expression of the cyclin-dependent kinase inhibitor p21 and dephosphorylation of the retinoblastoma protein (pRB). Cell proliferation block and cellular senescence induction in response to IGFBP-rP1 were partially reversed by p21 knockdown in MCF-7 cells. Knockdown of p53 in MCF-7 cells did not influence the growth inhibition, cellular senescence, and p21 expression of the cells in response to IGFBP-rP1 transfection.

CONCLUSIONS

Results from this study suggest that cellular senescence induced by IGFBP-rP1 is mediated at least in part by p21 enhanced expression, which regulated through the p53-independent pathway. IGFBP-rP1 might be one of the key molecules that trigger cellular senescence in breast cancer. Restoration of IGFBP-rP1 function might have therapeutic significance in breast cancer.

Insulin-like growth factor-binding protein-7 functions as a potential tumor suppressor in hepatocellular carcinoma

PURPOSE

Hepatocellular carcinoma (HCC) is a highly virulent malignancy with no effective treatment, thus requiring innovative and effective targeted therapies. The oncogene astrocyte-elevated gene-1 (AEG-1) plays a seminal role in hepatocarcinogenesis and profoundly downregulates insulin-like growth factor-binding protein-7 (IGFBP7). The present study focuses on analyzing potential tumor suppressor functions of IGFBP7 in HCC and the relevance of IGFBP7 downregulation in mediating AEG-1 function.

EXPERIMENTAL DESIGN

IGFBP7 expression was detected by immunohistochemistry in HCC tissue microarray and real-time PCR and ELISA in human HCC cell lines. Dual FISH was done to detect LOH at IGFBP7 locus. Stable IGFBP7-overexpressing clones were established in the background of AEG-1-overexpressing human HCC cells and were analyzed for in vitro proliferation and senescence and in vivo tumorigenesis and angiogenesis.

RESULTS

IGFBP7 expression is significantly downregulated in human HCC samples and cell lines compared with normal liver and hepatocytes, respectively, and inversely correlates with the stages and grades of HCC. Genomic deletion of IGFBP7 was identified in 26% of patients with HCC. Forced overexpression of IGFBP7 in AEG-1-overexpressing HCC cells inhibited in vitro growth and induced senescence, and profoundly suppressed in vivo growth in nude mice that might be an end result of inhibition of angiogenesis by IGFBP7.

CONCLUSION

The present findings provide evidence that IGFBP7 functions as a novel putative tumor suppressor for HCC and establish the corollary that IGFBP7 downregulation can effectively modify AEG-1 function. Accordingly, targeted overexpression of IGFBP7 might be a potential novel therapy for HCC.

Trastuzumab regulates IGFBP-2 and IGFBP-3 to mediate growth inhibition: implications for the development of predictive biomarkers for trastuzumab resistance

Activation of insulin-like growth factor-I receptor (IGF-IR) signaling is an important mechanism for trastuzumab resistance. IGF-binding proteins (IGFBP) modulate IGF-IR signaling and play important roles in the control of breast cancer progression. In this article, we report that trastuzumab treatment enhances the expression and secretion of IGFBP-3 in SKBR3 cells, a trastuzumab-sensitive breast cancer cell line, and that this upregulation of IGFBP-3 induced by trastuzumab correlates with trastuzumab-mediated growth inhibition. We describe a new role for IGFBP-3 in the regulation of IGF-I-mediated cross-talk between IGF-IR and ErbB2 signaling pathways. In particular, treatment of SKBR3 cells with recombinant IGFBP-3 blocks IGF-I-induced activation of IGF-IR and ErbB2, and stable expression of IGFBP-3 inhibits SKBR3 cell growth. We find an inverse relationship in the levels of secreted IGFBP-3 such that high levels of IGFBP-3 are associated with trastuzumab-sensitive breast cancer cells (SKBR3 and BT-474), whereas low levels of IGFBP-3 are found in trastuzumab-resistant cells (clone 3 and JIMT-1). In contrast to IGFBP-3, the secretion and expression of IGFBP-2 are upregulated in trastuzumab-resistant SKBR3 cells. Furthermore, we show that IGFBP-2 stimulates activation of ErbB2 and that trastuzumab reduces IGFBP-2-stimulated ErbB2 activation. Based on our data, we propose a novel mechanism of action whereby trastuzumab enhances the expression and secretion of IGFBP-3, which interferes with IGF-I-mediated mitogenic signaling via autocrine and paracrine mechanisms and reduces IGFBP-2-induced ErbB2 activation to mediate growth inhibition. Changes in secretion profiles of IGFBP-2 and IGFBP-3 in trastuzumab-sensitive and trastuzumab-resistant cells may promote the development of IGFBP-2 and IGFBP-3 as predictive biomarkers for trastuzumab resistance.

Alterations of insulin-like growth factor binding protein 3 (IGFBP-3) glycosylation in patients with breast tumours

OBJECTIVES

Insulin-like growth factor binding protein-3 (IGFBP-3) is an important modulator of development and progression of breast cancer as it regulates the amount of free, physiologically active IGF-I and IGF-II. Changes in the glycosylation pattern within IGFBP-3 may affect its interaction with ligands. The aim of this study was to investigate whether such changes occur during disease progression.

DESIGN AND METHODS

IGFBP-3 in serum samples from healthy women and from women with breast tumours was characterised in terms of its concentration (IRMA), glycosylation moiety (lectin-affinity chromatography) and distribution of molecular species (immunoblotting).

RESULTS

In patients with benign tumours the concentration and carbohydrate content of IGFBP-3 was unaltered compared to healthy women. In patients with malignant tumours in most cases these two parameters were unchanged, but there were women whose concentration of IGFBP-3 was reduced and its structure was altered. In non-surviving cancer patients the concentration of IGFBP-3 was significantly reduced and these molecules contained a greater amount of biantennary complex type N-glycans having more mannose, fucose, bisecting GlcNAc and terminal sialic acid residues.

CONCLUSION

Our results showed that breast cancer progression causes alterations of IGFBP-3 glycosylation. The extent of changes increases with breast cancer severity.

Genetic variation and circulating levels of IGF-I and IGFBP-3 in relation to risk of proliferative benign breast disease

Insulin-like growth factor-I (IGF-I) and its major binding protein IGFBP-3 have been implicated in breast carcinogenesis. We examined the associations between genetic variants and circulating levels of IGF-I and IGFBP-3 with proliferative benign breast disease (BBD), a marker of increased breast cancer risk, in the Nurses' Health Study II (NHSII). Participants were 359 pathology-confirmed proliferative BBD cases and 359 matched controls. Circulating IGF-I and IGFBP-3 levels were measured in blood samples collected between 1996 and 1999. Thirty single nucleotide polymorphisms (SNPs) in IGF-I, IGFBP-1, and IGFBP-3 genes were selected using a haplotype tagging approach and genotyped in cases and controls. Circulating IGF-I levels were not associated with proliferative BBD risk. Higher circulating IGFBP-3 levels were significantly associated with increased risk of proliferative BBD (highest vs. lowest quartile odds ratio (OR) [95% confidence interval (CI)], 1.70 (1.06-2.72); p-trend = 0.03). The minor alleles of 2 IGFBP-3 SNPs were associated with lower proliferative BBD risk (homozygous variant vs. homozygous wild-type OR (95% CI): rs3110697: 0.6 (0.4-0.9), p-trend = 0.02; rs2132570: 0.2 (0.1-0.6), p-trend = 0.02). Three other IGFBP-3 SNPs (rs2854744, rs2960436 and rs2854746) were significantly associated with circulating IGFBP-3 levels (p < 0.01). Although these SNPs were not significantly associated with proliferative BBD risk, there was suggestive evidence that the alleles associated with higher circulating IGFBP-3 levels were also associated with higher risk of proliferative BBD. These results suggest that genetic variants and circulating levels of IGFBP-3 may play a role in the early stage of breast carcinogenesis.

t10,c12-Conjugated linoleic acid stimulates mammary tumor progression in Her2/ErbB2 mice through activation of both proliferative and survival pathways

The t10,c12 isomer of conjugated linoleic acid (CLA) inhibits rat mammary carcinogenesis, metastasis from a transplantable mouse mammary tumor and angiogenesis; however, it stimulates mammary tumorigenesis in transgenic mice overexpressing ErbB2 in the mammary epithelium (ErbB2 transgenic mice). In the current study, we report that a 4-week supplementation of the diet with 0.5% trans-10, cis-12 conjugated linoleic acid (t10,c12-CLA) stimulated the growth of established ErbB2-overexpressing mammary tumors by 30% and increased the number of new tumors from 11% to 82%. Additionally, when t10,c12-CLA supplementation of ErbB2 transgenic mice was initiated at 21 weeks of age, a time just prior to tumor appearance, overall survival was decreased from 46.4 weeks in the control to 39.0 weeks in the CLA group, and survival after detection of a palpable tumor from 7.5 to 4.6 weeks. Short-term supplementation from 10 to 14 weeks or 21 to 25 weeks of age temporarily accelerated tumor development, but over the long term, there was no significant effect on mammary tumorigenesis. Long term as well as a short 4-week supplementation increased mammary epithelial hyperplasia and lobular development, and altered the mammary stroma; this was reversible in mice returned to the control diet. t10,c12-CLA altered proliferation and apoptosis of the mammary epithelium, although this differed depending on the length of administration and/or the age of the mice. The increased tumor development with t10,c12-CLA was associated with increased phosphorylation of the IGF-I/insulin receptor, as well as increased signaling through the mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase and phosphatidylinositol 3-kinase/Akt pathways; however, neither phospho-ErbB2 nor ErbB2 was altered.