Growth factors: mechanism of action and relation to oncogenes

An Integrative Clinical Model for the Prediction of Pathological Complete Response in Patients with Operable Stage II and Stage III Triple-Negative Breast Cancer Receiving Neoadjuvant Chemotherapy

Simple Summary

Neoadjuvant chemotherapy (NAC) is widely used to treat stage II and III primary, operable triple-negative breast cancer (TNBC). The response to NAC critically affects the subsequent treatment plan, including not only curative surgical planning but also adjuvant therapy. There is no standard prediction model that accurately predicts NAC response. Therefore, the development of an easy-to-apply and cost-effective clinical prediction model for NAC treatment response would improve clinical practice. We propose an integrative clinical prediction model for the prediction of pathologically complete response in patients with operable stage II and stage III TNBC receiving NAC based on findings from tumor ultrasound and blood tests. All included parameters were readily available during and before NAC. This clinical prediction model could provide a reference to guide clinicians’ decisions in planning a patient’s NAC treatment as early as after the first cycle of NAC.

Abstract

Triple-negative breast cancer (TNBC) is treated with neoadjuvant chemotherapy (NAC). The response to NAC, particularly the probability of a complete pathological response (pCR), guides the surgical approach and adjuvant therapy. We developed a prediction model using a nomogram integrating blood tests and pre-treatment ultrasound findings for predicting pCR in patients with stage II or III operable TNBC receiving NAC. Clinical data before and after the first cycle of NAC collected from patients between 2012 and 2019 were analyzed using univariate and multivariate analyses to identify correlations with pCR. The coefficients of the significant parameters were calculated using logistic regression, and a nomogram was developed based on the logistic model to predict the probability of pCR. Eighty-eight patients were included. Five parameters correlated with the probability of pCR, including the neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte (PLR) ratio, percentage change in PLR, presence of echogenic halo, and tumor height-to-width ratio. The discrimination performance of the nomogram was indicated by an area under the curve of 87.7%, and internal validation showed that the chi-square value of the Hosmer–Lemeshow test was 7.67 (p = 0.363). Thus, the integrative prediction model using clinical data can predict the probability of pCR in patients with TNBC receiving NAC.

Oral biosciences: The annual review 2021

BACKGROUND

The Journal of Oral Biosciences is devoted to advancing and disseminating fundamental knowledge concerning every aspect of oral biosciences.

HIGHLIGHT

This review features review articles in the fields of "Extracellular Vesicles," "Propolis," "Odontogenic Tumors," "Periodontitis," "Periodontium," "Flavonoids," "Lactoferrin," "Dental Plaque," "Anatomy," "Induced Pluripotent Stem Cells," "Bone Cell Biology," "Dysgeusia," "Dental Caries," and "Dental Pulp Cavity," in addition to the review article by the winners of the "Lion Award" ("Sox9 function in salivary gland development") presented by the Japanese Association for Oral Biology.

CONCLUSION

These reviews in the Journal of Oral Biosciences have inspired its readers to broaden their knowledge regarding various aspects of oral biosciences. The current editorial review introduces these exciting review articles.

Insight into the molecular pathogenesis of odontogenic lesions

BACKGROUND

Odontogenic tumors, derived from epithelial, ectomesenchymal, and/or mesenchymal elements of the tooth-forming apparatus, constitute a heterogeneous group of lesions, including hamartomas, benign and malignant neoplasms with metastatic capabilities.

HIGHLIGHT

This review provides a comprehensive overviewof the pathogenesis of odontogenic tumors and explains the associated molecular events in the context of hallmarks of cancer established by Hanahan D and Weinberg RA. Diagrammatic representations depicted in the article would facilitate easier understanding.

CONCLUSION

A better understanding of the pathogenesis of the lesions may assist in determining patient's prognosis and devising better targeted therapeutic treatment, thus, reducing the morbidity and mortalityof patients.

Factors predictive of invasive ductal carcinoma in cases preoperatively diagnosed as ductal carcinoma in situ

Background

Invasion is often found during postoperative pathological examination of cases diagnosed as ductal carcinoma in situ (DCIS) by histological examinations such as core needle biopsy (CNB) or vacuum-assisted biopsy (VAB). A meta-analysis reported that 25.9% of invasive ductal carcinoma (IDC) cases are preoperatively diagnosed by CNB as DCIS. Risk factors for invasion have been studied by postoperative examination, but no factors have been found that could be obtained preoperatively from blood tests. In this study, we investigated factors predictive of invasion based on preoperative blood tests in patients diagnosed with DCIS by preoperative biopsy.

Methods

In this study, 118 patients who were diagnosed with DCIS by preoperative biopsy were included. Biopsies were performed with 16-gauge CNB or VAB. Peripheral blood was obtained at the time of diagnosis. This study evaluated absolute platelet count, absolute lymphocyte count, lactate dehydrogenase, carcinoembryonic antigen, and cancer antigen 15–3 (CA15–3). The platelet–lymphocyte ratio (PLR) was calculated by dividing the absolute platelet count by the absolute lymphocyte count, and patients were grouped into high PLR (≥160.0) and low PLR (< 160.0) groups.

Results

Invasion was found more frequently after surgery in pathologically high-grade cases than in pathologically not-high-grade cases (p = 0.015). The median PLR was 138.9 and 48 patients (40.7%) were classified into the high PLR group. The high PLR group was significantly more likely to have invasion detected by the postoperative pathology than the low PLR group (p = 0.018). In multivariate analysis of factors predictive of invasion in postoperative pathology, a high PLR (p = 0.006, odds ratio [OR] = 3.526) and biopsy method (VAB vs. CNB, p = 0.001, OR = 0.201) was an independent risk factor.

Conclusions

The PLR may be a predictor of invasion in the postoperative pathology for patients diagnosed with DCIS by preoperative biopsy.

Clinical application of injectable growth factor for bone regeneration: a systematic review

Bone regeneration has been the ultimate goal in the field of bone and joint medicine and has been evaluated through various basic research studies to date. Translational research of regenerative medicine has focused on three primary approaches, which are expected to increase in popularity: cell therapy, proteins, and artificial materials. Among these, the local injection of a gelatin hydrogel impregnated with the protein fibroblast growth factor (FGF)-2 is a biomaterial technique that has been developed in Japan. We have previously reported the efficacy of gelatin hydrogel containing injectable FGF-2 for the regenerative treatment of osteonecrosis of the femoral head. Injectable growth factors will probably be developed in the future and gain popularity as a medical approach in various fields as well as orthopedics. Several clinical trials have already been conducted and have focused on this technique, reporting its efficacy and safety. To date, reports of the clinical application of FGF-2 in revascularization for critical limb ischemia, treatment of periodontal disease, early bone union for lower limb fracture and knee osteotomy, and bone regeneration for osteonecrosis of the femoral head have been based on basic research conducted in Japan. In the present report, we present an extensive review of clinical applications using injectable growth factors and discuss the associated efficacy and safety of their administration.

Platelet-Lymphocyte Ratio as a Useful Predictor of the Therapeutic Effect of Neoadjuvant Chemotherapy in Breast Cancer

Background

The peripheral blood platelet–lymphocyte ratio (PLR) has been proposed as an indicator for evaluating systemic inflammatory responses in cancer-bearing patients. While some reports suggest a correlation between PLR and prognosis, few studies have examined the relationship between PLR and sensitivity to chemotherapy. We conducted a study on whether PLR could serve as a predictor of the therapeutic effects of neoadjuvant chemotherapy (NAC).

Methods

PLR was evaluated in 177 breast cancer patients treated with the NAC 5-fluorouracil, epirubicin and cyclophosphamide, followed by weekly paclitaxel and subsequent curative surgery. The correlation between PLR and prognosis, and between PLR and the efficacy of NAC, were evaluated retrospectively.

Results

The low PLR group had significantly more patients > 56 years old (p = 0.001) and postmenopausal women (p = 0.001) than the high PLR group. The low PLR group also had a higher pathologic complete response (pCR) rate (p = 0.019). On examining the correlation with prognosis, the low-PLR group was found to have significantly longer disease-free survival (p = 0.004) and overall survival (p = 0.032) than the high PLR group. Multivariate analysis also revealed that lymph node metastasis (p = 0.043, hazard ratio = 4.40) and a high PLR (p = 0.005, hazard ratio = 2.84) were independent, unfavorable prognostic factors.

Conclusions

For patients with breast cancer treated with NAC, a low PLR indicated high chemotherapy sensitivity, suggesting that PLR could serve as a predictive marker of the therapeutic effect of NAC.

Imatinib mesylate inhibits cell growth of malignant peripheral nerve sheath tumors in vitro and in vivo through suppression of PDGFR-β

BACKGROUND

Malignant peripheral nerve sheath tumors (MPNSTs) are highly aggressive and associated with poor prognosis. Basic research to develop new treatment regimens is critically needed.

METHODS

The effects of imatinib mesylate on MPNSTs were examined in six human MPNST cell lines and in a xenograft mouse model.

RESULTS

The results showed expression of platelet-derived growth factor receptor-β and suppression of its phosphorylation by imatinib mesylate in all six cell lines. Imatinib mesylate effectively suppressed MPNST cell growth in vitro at concentrations similar to those used clinically (1.46 - 4.6 μM) in three of six cell lines. Knockdown of PDGFR-β by transfection with a specific siRNA also caused significant reduction in cell proliferation in the sensitive cell lines, but not in the resistant cell lines. Furthermore, imatinib mesylate also significantly suppressed colony formation within soft agar and tumor growth in xenograft models using two of the three sensitive MPNST cell lines. There was excellent agreement between in vitro and in vivo sensitivity to imatinib mesylate, suggesting possible selection of imatinib-sensitive tumors by in vitro analysis.

CONCLUSIONS

The results suggest that imatinib mesylate may be useful in the treatment of MPNST patients and in vitro studies may help select cells that are sensitive to imatinib mesylate in vivo.

Autocrine PDGF stimulation in malignancies

Platelet-derived growth factor (PDGF) isoforms are important mitogens for different types of mesenchymal cells, which have important functions during the embryonal development and in the adult during wound healing and tissue homeostasis. In tumors, PDGF isoforms are often over-expressed and contribute to the growth of both normal and malignant cells. This review focuses on tumors expressing PDGF isoforms together with their tyrosine kinase receptors, thus resulting in autocrine stimulation of growth and survival. Patients with such tumors could benefit from treatment with inhibitors of either PDGF or PDGF receptors.

Glioblastoma--a moving target

The slow development of effective treatment of glioblastoma is contrasted by the rapidly advancing research on the molecular mechanisms underlying the disease. Amplification and overexpression of receptor tyrosine kinases, particularly EGFR and PDGFRA, are complemented by mutations in the PI3K, RB1, and p53 signaling pathways. In addition to finding effective means to target these pathways, we may take advantage of the recent understanding of the hierarchical structure of tumor cell populations, where the progressive expansion of the tumor relies on a minor subpopulation of glioma stem cells, or glioma-initiating cells. Finding ways to reprogram these cells and block their self-renewal is one of the most important topics for future research.

Regulation of IMP3 by EGFR signaling and repression by ERβ: implications for triple-negative breast cancer

Insulin-like growth factor II (IGF-II) mRNA binding protein 3 (IMP3) is emerging as a useful indicator of the progression and outcome of several cancers. IMP3 expression is associated with triple-negative breast carcinomas (TNBCs), which are aggressive tumors associated with poor outcome. In this study, we addressed the hypothesis that signaling pathways, which are characteristic of TNBCs, impact the expression of IMP3 and that IMP3 contributes to the function of TNBCs. The data obtained reveal that IMP3 expression is repressed specifically by estrogen receptor β (ERβ) and its ligand 3βA-diol but not by ERα. EGF receptor (EGFR) signaling and consequent activation of the MAP kinase pathway induce IMP3 transcription and expression. Interestingly, we discovered that the EGFR promoter contains an imperfect estrogen response element and that ERβ represses EGFR transcription. These data support a mechanism in which ERβ inhibits IMP3 expression indirectly by repressing the EGFR. This mechanism relates to the biology of TNBC, which is characterized by diminished ERβ and increased EGFR expression. We also demonstrate that IMP3 contributes to the migration and invasion of breast carcinoma cells. Given that IMP3 is an mRNA binding protein, we determined that it binds several key mRNAs that could contribute to migration and invasion including CD164 (endolyn) and MMP9. Moreover, expression of these mRNAs is repressed by ERβ and enhanced by EGFR signaling, consistent with our proposed mechanism for the regulation of IMP3 expression in breast cancer cells. Our findings show that IMP3 is an effector of EGFR-mediated migration and invasion and they provide the first indication of how this important mRNA binding protein is regulated in cancer.

Malignant peripheral nerve sheath tumour (MPNST): the clinical implications of cellular signalling pathways

Malignant peripheral nerve sheath tumour (MPNST) is a rare malignancy accounting for 3–10% of all soft tissue sarcomas. Most MPNSTs arise in association with peripheral nerves or deep neurofibromas and may originate from neural crest cells, although the specific cell of origin is uncertain. Approximately half of MPNSTs occur in the setting of neurofibromatosis type 1 (NF1), an autosomal dominant disorder with an incidence of approximately one in 3500 persons; the remainder of MPNSTs develop sporadically. In addition to a variety of clinical manifestations, approximately 8–13% of NF1 patients develop MPNSTs, which are the leading cause of NF1-related mortality. Surgical resection is the mainstay of MPNST clinical management. However, because of invasive growth, propensity to metastasise, and limited sensitivity to chemotherapy and radiation, MPNST has a guarded to poor prognosis. Five-year survival rates of only 20–50% indicate an urgent need for improved therapeutic approaches. Recent work in this field has identified several altered intracellular signal transduction cascades and deregulated tyrosine kinase receptors, posing the possibility of personalised, targeted therapeutics. However, expanded knowledge of MPNST molecular pathobiology will be needed to meaningfully apply such approaches for the benefit of afflicted patients.

Signalling mitogenesis in 3T3 cells: role of Ca2+-sensitive, phospholipid-dependent protein kinase

Understanding the molecular mechanisms that control cell proliferation requires the identification of the early signals important for initiating a mitogenic response. In this context, the activation of Ca2+-sensitive, phospholipid-dependent protein kinase (protein kinase C), which is stimulated by diacylglycerols and serves as a major phorbol ester receptor, may play an important part in signalling mitogenesis. This conclusion is based on two main lines of evidence. Firstly, activation of protein kinase C in intact quiescent fibroblasts is one of the earliest events elicited by a variety of growth-promoting agents including serum, platelet-derived growth factor (PDGF), vasopressin and bombesin, as judged by the increase in the phosphorylation of a cellular protein characterized by an Mr of 80 000 and a pI of 5. Secondly, the synthetic diacylglycerol, 1-oleoyl-2-acetylglycerol, which directly competes with [3H]phorbol dibutyrate for binding to specific receptors in intact 3T3 cells and rapidly stimulates protein kinase C in these cells, is a potent mitogen for Swiss 3T3 cells, acting synergistically with other growth factors. We propose that activation of protein kinase C may be one of the early signals that mediate the mitogenic effects of a variety of growth factors and peptide hormones in quiescent fibroblastic cells.

Effects of bFGF on suppression of collagen type I accumulation and scar tissue formation during wound healing after mucoperiosteal denudation of rat palate

OBJECTIVE

The purpose of this study was to evaluate the effect of basic fibroblast growth factor (bFGF) on collagen changes after mucoperiosteal denudation of rat palate.

MATERIAL AND METHODS

A total of 36 male Wistar rats were divided into control, scar, sham, and bFGF groups. In the scar, sham, and bFGF groups, lateral palatal mucoperiosteum was excised to form scar tissue on the palate. In the bFGF group, bFGF solution was injected into the operated area 1 week postoperatively. At 6 weeks postoperatively, the distribution of collagen type I and the 3-dimensional structure of collagen fibers were investigated under immunofluorescent and scanning electron microscopy.

RESULT

In the bFGF group, weakly immunostained submucosa was clearly distinguishable from the strongly immunostained cervical periodontal ligament and gingiva. Collagen fibers running from submucosal tissue into the surface of underlying palatal bone comprised loosely arranged collagen fibrils. Lumen structures in collagen fibers resembled those in the control group.

CONCLUSION

Administration of bFGF for suppression of collagen type I generation could suppress scar tissue formation and reduce connective strength with adjacent teeth and palatal bone.

Imatinib mesylate inhibits cell invasion of malignant peripheral nerve sheath tumor induced by platelet-derived growth factor-BB

Malignant peripheral nerve sheath tumor (MPNST) is rare, highly aggressive, resistant to radiochemotherapy, and associated with poor prognosis. Basic research to develop new treatment regimes is critically needed. This study was designed to identify motogenic factor(s) involved in MPNST cell invasion and inhibitor(s) of such invasive activity. We profiled the invasion-inducing activities of eight motogenic growth factors on two human MPNST cell lines, FU-SFT8611 and 9817, using in vitro Matrigel invasion assays. Platelet-derived growth factor-BB (PDGF-BB) was identified as the most effective MPNST cell invasion-inducing factor. Epidermal growth factor (EGF) and hepatocyte growth factor (HGF) also stimulated invasion in one MPNST cell line. Expressions of PDGF-BB and EGF receptors (PDGFR-beta and EGFR) mRNAs were detected more frequently and their proteins were expressed at higher levels in MPNST tissues than benign peripheral nerve sheath tumors (schwannomas and neurofibromas). In both MPNST cell lines, PDGF-BB induced tyrosine phosphorylation of PDGFR-beta but not of PDGFR-alpha, and specific PDGFR-beta inhibition by small interfering RNA to the receptor inhibited PDGF-BB-stimulated MPNST cell invasion, suggesting the predominant role of PDGFR-beta. Inhibition of PDGFR-beta phosphorylation by pretreatment with herbimycin A and imatinib mesylate effectively suppressed basement membrane invasion and cell growth in vitro. No mutations were present in exons 12 and 18 of PDGFR-beta in both MPNST cell lines and 10 human MPNST tissues examined. Our results indicated that PDGF-BB enhanced the invasive activity of MPNST cells through PDGFR phosphorylation and that imatinib inhibited such activity. The results provide the ground for further assessment of the therapeutic potential of imatinib in suppressing the invasion and growth of MPNST.

Immunohistochemical detection of insulin-like growth factors, platelet-derived growth factor, and their receptors in ameloblastic tumors

BACKGROUND

To evaluate the roles of growth factors in oncogenesis and cytodifferentiation of odontogenic tumors, expression of insulin-like growth factors (IGFs), platelet-derived growth factor (PDGF), and their receptors was analyzed in ameloblastic tumors as well as in tooth germs.

METHODS

Tissue specimens of 10 tooth germs, 47 ameloblastomas, and five malignant ameloblastic tumors were examined immunohistochemically with the use of antibodies against IGF-I, IGF-II, IGF-I receptor (IGF-IR), PDGF A-chain, PDGF B-chain, PDGF alpha-receptor, and PDGF beta-receptor.

RESULTS

Immunohistochemical reactivity for IGFs, PDGF chains, and their receptors was detected predominantly in odontogenic epithelial cells near the basement membrane in tooth germs and in benign and malignant ameloblastic tumors. The expression levels of IGF-II and PDGF chains were significantly higher in ameloblastic tumors than in tooth germs. Malignant ameloblastic tumors showed higher reactivity for PDGF chains than benign ameloblastomas and higher reactivity for platelet-derived growth factor receptors than tooth germs. The expression levels of PDGF chains were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. Desmoplastic ameloblastomas showed higher expression of IGFs and IGF-IR when compared with other ameloblastoma subtypes.

CONCLUSION

Expression of IGFs, PDGF, and their receptors in tooth germs and ameloblastic tumors suggests that these growth factor signals contribute to cell proliferation or survival in both normal and neoplastic odontogenic tissues. Expression of these molecules in odontogenic tissues possibly affects interactions with the bone microenvironment during tooth development and intraosseous progression of ameloblastic tumors. Altered expression of the ligands and receptors in ameloblastic tumors may be involved in oncogenesis, malignant potential, and tumor cell differentiation.

The phosphoglycerate mutases

The phosphoglycerate mutase family is generally very well documented with respect to structure, evolution, and mode of action. However, a few individuals in the family remain relatively poorly characterized and will clearly require more detailed study. Furthermore, certain aspects of the detailed behavior of these enzymes are, as yet, incompletely understood and require further investigation. Cofactor-dependent monophosphoglycerate mutase and bisphosphoglycerate mutase are undoubtedly very closely related. Their amino acid sequences are strongly similar, they can form active heterodimers, and they catalyze the same three reactions, albeit at substantially different relative rates. Both enzymes catalyze a ping-pong type of reaction with a phosphohistidine intermediate. The presence of an additional phospho ligand at the active site of monophosphoglycerate mutase helps to explain why this enzyme is better at retaining the 2,3-bisphosphoglycerate intermediate and why it is thus more efficient (by a factor of about 10(3)) at catalyzing the interconversion of 3- and 2-phosphoglycerates. The reason why 1,3-bisphosphoglycerate is a better substrate for bisphosphoglycerate mutase than for monophosphoglycerate mutase (by a factor of about 30) is not yet apparent but presumably relates to the relative positioning of the two phospho-binding sites. Both enzymes are equally good as phosphatases when the reaction is activated by 2-phosphoglycollate. Available evidence indicates that these mutases are similar in many respects to the much smaller, cofactor-dependent monophosphoglycerate mutase from Schizosaccharomyces pombe, but further information is required to define the relationship more precisely. Cofactor-independent monophosphoglycerate mutase belongs to a quite distinct branch of the phosphoglycerate mutase family. It is not known at present whether this branch is related divergently or convergently to the cofactor-dependent monophosphoglycerate mutase/bisphosphoglycerate mutase branch. Existing evidence can be argued both ways. For example, the kinetic evidence shows a ping-pong type of reaction and would be consistent with a phosphohistidine intermediate as encountered in the other mutases. Thus the cofactor-independent enzyme may also have arisen by gene duplication--but, in this case, yielding an enzyme of about twice the size, with slightly different residues at the active site and C-terminal tail. An alternative possibility, of course, is that the two branches of the phosphoglycerate mutase family are quite unrelated in a divergent sense and are little more similar structurally than is, for example, the catalytically similar enzyme phosphoglucomutase.(ABSTRACT TRUNCATED AT 400 WORDS)

Breast cancer cells secreted platelet-derived growth factor-induced motility of vascular smooth muscle cells is mediated through neuropilin-1

Motility of vascular smooth muscle cells (SMCs) is an essential step for both normal and pathologic angiogenesis. We report here that breast tumor cells, such as MCF-7 and MDA-MB-231, can modulate this SMC migration. We present evidence that the tumor cell-derived platelet-derived growth factor (PDGF) is the key regulator of vascular SMCs motility induced by breast cancer cells. PDGF significantly upregulates neuropilin-1 (NRP-1) mRNA expression and protein production in aortic smooth muscle cells (AOSMCs) and depletion of NRP-1 production by AOSMCs with specific short hairpin RNA (shRNA) prevents the PDGF-dependent migration of vascular SMCs. Moreover, we demonstrate that PDGF physically interacts with NRP-1. We propose that tumor-derived PDGF and NRP-1 of AOSMCs function as a relay system that promotes motility of vascular SMCs.

Molecular pathology of odontogenic tumors

Odontogenic tumors are lesions derived from the elements of the tooth-forming apparatus and are found exclusively within the jawbones. This review represents a contemporary outline of our current understanding of the molecular and genetic alterations associated with the development and progression of odontogenic tumors, including oncogenes, tumor-suppressor genes, oncoviruses, growth factors, telomerase, cell cycle regulators, apoptosis-related factors, regulators of tooth development, hard tissue-related proteins, cell adhesion molecules, matrix-degrading proteinases, angiogenic factors, and osteolytic cytokines. It is hoped that better understanding of related molecular mechanisms will help to predict the course of odontogenic tumors and lead to the development of new therapeutic concepts for their management.

Involvement of protein tyrosine kinase in Toll-like receptor 4-mediated NF-kappa B activation in human peripheral blood monocytes

Bacterial lipopolysaccharide (LPS) is a powerful activator of the innate immune system. Exposure to LPS induces an inflammatory reaction in the lung mediated primarily by human blood monocytes and alveolar macrophages, which release an array of inflammatory chemokines and cytokines including IL-8, TNF-alpha, IL-1beta, and IL-6. The signaling mechanisms utilized by LPS to stimulate the release of cytokines and chemokines are still incompletely understood. Pretreatment with the protein tyrosine kinase-specific inhibitors genistein and herbimycin A effectively blocked LPS-induced NF-kappaB activation as well as IL-8 gene expression in human peripheral blood monocytes. However, when genistein was added 2 min after the addition of LPS, no inhibition was observed. Utilizing a coimmunoprecipitation assay, we further showed that LPS-stimulated tyrosine phosphorylation of Toll-like receptor 4 (TLR4) may be involved in downstream signaling events induced by LPS. These findings provide evidence that LPS-induced NF-kappaB activation and IL-8 gene expression use a signaling pathway requiring protein tyrosine kinase and that such regulation may occur through tyrosine phosphorylation of TLR4.

Immunohistochemical detection of hepatocyte growth factor, transforming growth factor-β and their receptors in epithelial odontogenic tumors

BACKGROUND

Tumors derived from odontogenic epithelium exhibit considerable variation and are classified into several benign and malignant entities. To clarify the role of growth factors in oncogenesis, cytodifferentiation and progression of epithelial odontogenic tumors, expression of hepatocyte growth factor (HGF), transforming growth factor-beta (TGF-beta) and their receptors were analyzed in these tumors as well as in tooth germs.

METHODS

Specimens of five tooth germs, 34 ameloblastomas, three calcifying epithelial odontogenic tumors (CEOTs), two clear cell odontogenic tumors (CCOTs), five adenomatoid odontogenic tumors (AOTs), six calcifying odontogenic cysts (COCs) and six malignant ameloblastomas were examined immunohistochemically with the use of antibodies against HGF, TGF-beta and their receptors.

RESULTS

In tooth germs and epithelial odontogenic tumors, immunoreactivity for HGF and TGF-beta was detected in both epithelial and mesenchymal cells, while expression of their receptors was found only in epithelial cells. In tooth germs and main types of ameloblastomas, HGF and TGF-beta reactivity was marked in epithelial cells near the basement membrane, and their receptors were diffusely positive in most epithelial cells. In subtypes of ameloblastomas, reduced expression of HGF, c-Met and TGF-beta and increased reactivity for TGF-beta receptors were detected in keratinizing cells in acanthomatous ameloblastomas, and granular cells in granular cell ameloblastomas demonstrated little or no expression of HGF, TGF-beta or their receptors. As compared with main types of ameloblastomas, basal cell ameloblastomas showed high HGF reactivity, and desmoplastic ameloblastomas exhibited elevated reactivity for TGF-beta and its receptors. Neoplastic cells in CEOTs, AOTs and COCs showed reactivity for HGF, TGF-beta and their receptors. Elevated HGF and TGF-beta reactivity was found in pseudoglandular cells in AOTs, and high expression of their receptors was noted in ghost cells in COCs. Metastasizing ameloblastomas showed similar expression patterns of HGF, TGF-beta and their receptors to those of benign ameloblastomas, while CCOTs and ameloblastic carcinomas had increased HGF expression and low reactivity for TGF-beta and its receptors as compared with benign ameloblastomas.

CONCLUSIONS

Immunohistochemical localization of HGF, TGF-beta and their receptors in tooth germs and epithelial odontogenic tumors supports the hypothesis that HGF and TGF-beta act on epithelial cells via paracrine and autocrine mechanisms. Altered expression of the agents in these epithelial odontogenic tumors, especially subtypes of ameloblastomas, AOTs and COCs, suggests that HGF and TGF-beta signaling might affect differentiation of neoplastic odontogenic epithelial cells. Activated HGF/c-Met pathway and reduced TGF-beta signaling in CCOTs and ameloblastic carcinomas may be associated with the malignant potential of these epithelial odontogenic tumors.

Prognostic value of epidermal growth factor receptor (EGFR) and its relationship to the estrogen receptor status in 1029 patients with breast cancer

An epidermal growth factor receptor (EGFR) has been reported to be associated with a poor clinical outcome in breast cancer, while its prognostic value remains controversial. Immunohistochemical staining for EGFR was performed on frozen sections of primary breast cancer from 1029 patients with a mean follow-up duration of 46 months. EGFR was positive in 277 (26.9%) of 1029 cases which inversely correlated with the estrogen receptor (ER) status. A univariated analysis indicated that EGFR had a significant prognostic value in both the disease free survival (DFS) and the overall survival (OS), while the same effect was also found in node negative as well as node positive breast cancer. A multivariate analysis indicated that EGFR was an independently significant prognostic factor for DFS (p = 0.0174) and OS (p = 0.0105) in all patients, but that EGFR demonstrated a prognostic significance only for DFS (p = 0.0241) in node negative and only for OS (p = 0.0333) in node positive breast cancer. When all patients were stratified for EGFR and ER, a multivariate analysis indicated that the combination of EGFR(+)/ER(-) was an independently significant factor for both DFS and OS in node negative as well as node positive breast cancer. In conclusion, the prognostic value of EGFR was demonstrated by a multivariate analysis in a large series of breast cancer patients, but the value of EGFR was somewhat insufficient to achieve statistical significance for both DFS and OS in the subgroups divided by nodal status. On the other hand, the prognostic value of combination of EGFR and ER was sufficient to achieve statistical significance based on a multivariate analysis for both DFS and OS in the subgroups of node negative as well as node positive breast cancer patients.

Transforming growth factor-beta regulation of estradiol-induced prolactinomas

Prolactin-secreting adenomas (prolactinomas) are the most prevalent form of pituitary tumors in humans, and increased tumor growth under estrogenic influence in female patients is often of clinical concern. Extensive experimental work has uncovered the roles of estrogen receptors and various growth-regulatory peptides in estradiol action on lactotropes. However, it is only recently that we are beginning to gain insight into how these growth factors interact to regulate estradiol action on lactotrope cell proliferation. Recent studies have identified the regulatory role of TGF-beta-related peptides in estradiol action on lactotropes. Additionally, these studies determined that TGF-beta and FGF interact to facilitate the communication between lactotropes and folliculostellate cells that is necessary for the mitogenic action of estradiol. This review addresses the role of estradiol in prolactinoma formation and summarizes data that support a novel concept: Alterations in the expression and action of TGF-beta isoforms are crucial steps in estradiol-induced tumorigenesis.

The effects of platelet-derived growth factor-BB on periodontal cells in an in vitro wound model

BACKGROUND

Platelet-derived growth factor (PDGF-BB) has been shown to enhance periodontal regeneration. Principles of guided tissue regeneration dictate that one of the goals of therapy is to modulate the wound healing processes to favor repopulation of the wound with cells derived from the periodontal ligament rather than from the gingival tissues. Using an in vitro wound model, gingival fibroblasts (GF) have been shown to fill a wound space significantly faster than periodontal ligament cells (PDL). There are no data reported directly comparing the response of these 2 cell types to PDGF-BB within such a wound model. Therefore, the aims of this research were: 1) to characterize both the proliferative and wound fill (WF) effects of PDGF-BB within an in vitro model and 2) to compare specific growth factor effects between GF and PDL.

METHODS

Primary cultures of both human PDL and GF were derived from explanted tissues and passaged to 12-well tissue culture plates. Triplicate cultures of both cell types were grown to confluence and in vitro wounds were mechanically created, removing a 3 mm wide band of the cell layer across the diameter of the wells. The wells were then incubated for 2, 6, and 9 days in media containing 0.1% fetal bovine serum (FBS) and 1 of 5 concentrations of PDGF-BB. At each time point, cells were pulsed with 5-bromo, 2-deoxyuridine (BrdU) fixed, and nuclei were stained to measure BrdU incorporation (as a measure for proliferation). Cells were counter-stained with cytoplasmic stain to measure cell number. Quantitative analyses within the wound boundaries, marginally (area of interest [AOI] 1) and centrally (AOI 2), were accomplished using computer-assisted histomorphometry.

RESULTS

PDL exhibited a significantly greater proliferative response to PDGF-BB in both AOI when compared to GF (P <0.0001). The PDL exhibited increased levels of proliferation at concentrations of PDGF-BB greater than or equal to 10 ng/ml. By contrast, GF displayed no increase in proliferation in response to stimulation with PDGF-BB at any of the concentrations tested when compared to negative controls. The wound fill (WF) responses to PDGF-BB were similar between PDL and GF, with both cell types responding in an all or none fashion when measured at day 2, and in a concentration-dependent manner at later time points. The only significant difference in WF between PDL and GF occurred in AOI 2 in negative control medium (0 ng/ml of PDGF-BB), with GFs having greater (P <0.01) levels of WF over the 9 days.

CONCLUSION

The findings from this study demonstrate differing effects of PDGF-BB on the proliferation of PDL and GF in this in vitro model. These results suggest that there may be cell-specific differences critical to periodontal wound healing that may be exploited in the development of new therapies.

Effect of insulin stimulation on the proliferation and death of Chinese hamster ovary cells

The effect of environmental and genetic parameters on cell death was studied in Chinese hamster ovary cell cultures. Experiments were performed using an anchorage-dependent CHO cell line expressing gamma-IFN, and a second cell line obtained by transfection of the previous one with bcl-2. In serum-free medium the two cell lines showed a considerable degree of growth control entering quiescence while maintaining high viabilities. The addition of transferrin did not have any effect but insulin addition allowed cells arrested by serum withdrawal to reenter the cell cycle. However, insulin supplementation also resulted in cell death, which was possible to avoid through bcl-2 overexpression or in the presence of serum. We propose that the expression of c-myc, shown to be induced by insulin, plays an important role in the cell death observed after insulin addition in an inappropriate environment, deficient in protective factors. This hypothesis is supported by measurements of c-myc expression and cell cycle distribution.

Epidermal growth factor receptor signaling activates met in human anaplastic thyroid carcinoma cells

Overexpression of Met is a common finding in thyroid carcinomas. Recently, we reported on overexpression and ligand-independent constitutive activation of Met in anaplastic thyroid carcinoma cells. In the present study we have investigated a putative mechanism for this phenomenon. Cell lines with constitutively activated Met expressed both TGF-alpha mRNA and protein. Western blot analysis revealed expression of receptors for epidermal growth factor (EGFR) in all carcinoma cell lines; in tumor cells with elevated levels of TGF-alpha mRNA there was a constitutive tyrosine phosphorylation of the EGFRs. Preincubation of carcinoma cells with suramin decreased EGFR activation and downregulated Met expression as well as the ligand-independent phosphorylation of Met. Similar results were obtained with a EGFR tyrosine kinase inhibitor, AG 1478. The MEK inhibitor U0126 had an even more pronounced effect compared to AG 1478, indicating a Ras/MAPK-mediated signal in the regulation of Met expression and activation. Inhibition of EGFR signaling also decreased proliferation of the anaplastic thyroid carcinoma cells. Thus, aberrant activation of EGFRs may lead to an overexpression and activation of Met, which may be of importance for the malignant phenotype of anaplastic thyroid carcinomas.

Cloning and characterization of the promoter region of the rat epidermal growth factor receptor gene and its transcriptional regulation by nerve growth factor in PC12 cells

Our previous studies have shown that treatment of PC12 cells with nerve growth factor (NGF) causes a profound down-regulation of the epidermal growth factor receptor (EGFR) mRNA and protein. Further, the NGF-induced down-regulation of the EGFR is under transcriptional control. To elucidate the molecular mechanism of this down-regulation we have cloned a 2.7-kilobase sequence from the promoter region of the rat EGFR from a rat P1 library. Six transcriptional start sites were identified by 5'-rapid amplification of cDNA ends and primer extension. Sequence analysis showed a 62% overall homology with the human EGFR promoter region. To investigate its transcription, 1.1 kilobases of the 5'-flanking sequence were fused to a luciferase reporter gene. This sequence exhibited functional promoter activity in transient transfection experiments with PC12, C6, and CV-1 cells. Treatment of PC12 cells with NGF inhibited promoter activity. By transfection of promoter deletion constructs, a silencer element was found between nucleotides -260 and -181, and TCC repeat sequences appeared to be at least partially responsible for the down-regulation of the EGFR by NGF. Supportive evidence for the relevance of this sequence was obtained from gel mobility shift assays and by transfection of TCC mutation constructs. Our results demonstrate that TCC repeat sequences are required for the down-regulation of rat EGFR by NGF in PC12 cells and may lead to the identification of the NGF-responsive transcription factors.

The Drosophila centrosomal protein Nuf is required for recruiting Dah, a membrane associated protein, to furrows in the early embryo

During mitosis of the Drosophila cortical syncytial divisions, actin-based membrane furrows separate adjacent spindles. Our genetic analysis indicates that the centrosomal protein Nuf is specifically required for recruitment of components to the furrows and the membrane-associated protein Dah is primarily required for the inward invagination of the furrow membrane. Recruitment of actin, anillin and peanut to the furrows occurs normally in dah-derived embryos. However, subsequent invagination of the furrows fails in dah-derived embryos and the septins become dispersed throughout the cytoplasm. This indicates that stable septin localization requires Dah-mediated furrow invagination. Close examination of actin and Dah localization in wild-type embryos reveals that they associate in adjacent particles during interphase and co-localize in the invaginating furrows during prophase and metaphase. We show that the Nuf centrosomal protein is required for recruiting the membrane-associated protein Dah to the furrows. In nuf-mutant embryos, much of the Dah does not reach the furrows and remains in a punctate distribution. This suggests that Dah is recruited to the furrows in vesicles and that the recruiting step is disrupted in nuf mutants. These studies lead to a model in which the centrosomes play an important role in the transport of membrane-associated proteins and other components to the developing furrows.

Effect of transforming RNA on the synthesis of a protein with a secretory signal sequence in vitro

U5 small nuclear RNA itself can act as a clastogenic and transforming agent when transfected into cells. In the previous work, the 3' half of the U5 small nuclear RNA first stem structure (designated RNA3S) was capable of driving normal cells into tumorigenic cells when expressed with a poly(A) tail (RNA3S+). This transformation critically depended upon the polypurine sequence GGAGAGGAA in RNA3S+. In this work, we first examined the pre-beta-lactamase and luciferase (model secretory and nonsecretory proteins) translation with the in vitro synthesized RNA3S in rabbit reticulocyte lysate. The capped RNA3S with a poly(A) tail suppressed the translation. In addition, the polypurine sequence played a crucial role in affecting the secretory protein synthesis, indicating a primary action of RNA3S+. Further studies revealed that the oligodeoxynucleotides, corresponding to the polypurine and its antisense sequences, directly contacted 28 S rRNA in ribosome and 7SL RNA in signal recognition particle, respectively, and differentially affected the nascent chain elongation of secretory protein synthesis. These results suggest that RNA3S+ blocks a physiological regulatory function played by signal recognition particle and the ribosome in the secretory protein synthesis and support the idea that the transformation might result from a repressed cellular activity.

Expression of receptors for basic fibroblast growth factor on human periodontal ligament cells

Basic fibroblast growth factor (FGF-2; bFGF) is a major mitogen for connective tissue cells, and participates in the healing process. It has already been reported that FGF-2 could be applicable to enhance periodontal regeneration. In the present study, we examined FGF receptor (FGFR) expression on human periodontal ligament (PDL) cells. The binding of [125I]-labeled FGF-2 to human PDL cells was studied by radioreceptor assay. The binding of [125I]-FGF-2 to PDL cells reached a plateau after 2.5 h incubation at 4 degrees C and was inhibited by the addition of unlabeled FGF-2 and acidic FGF (FGF-1; aFGF), but not insulin-like growth factor-I, platelet-derived growth factor and transforming growth factor-beta 1. Scatchard analysis revealed the presence of approximately 1.0 x 10(5) FGF-2 binding sites per cell with an apparent Kd of 1.2 x 10(-10) M. Interestingly, the binding of [125I]-FGF-2 on PDL cells reached its maximum at d 6 of the culture and then gradually decreased. Scatchard analysis also demonstrated that the number of FGFRs on a PDL cell was altered during the course of the culture, while the affinity between FGF-2 and its receptor was not. The responsiveness of PDL cells to FGF-2, which was monitored by the inhibitory effect on alkaline phosphatase activity, was reduced in proportion to the decrease in the number of FGFRs on the PDL cells. The present study suggests that PDL cells alter the responsiveness to FGF-2 during the course of the culture by changing the density of its receptor, and that the density of FGFR expression might be a marker of the cytodifferentiation of PDL cells into mineralized tissue forming cells.

Activation-dependent expression of the insulin-like growth factor binding protein-2 in human lymphocytes

The expression of the insulin-like growth factor binding protein-2 (IGFBP-2) was assayed in mononuclear cells originating from different organs of the immune system. All mononuclear cells studied did express IGFBP-2, but the expression level was found to be dependent on the cell type and origin of the cell. T cells showed a higher expression of IGFBP-2 mRNA than did B cells, and CD34+ stem cells expressed IGFBP-2 mRNA at a high level. Expression was highest in bone marrow and thymus. Stimulation of peripheral mononuclear cells resulted in a marked increase of IGFBP-2 mRNA and also intracellular IGFBP-2, as analysed by fluorescence staining. This increase parallels the increase of other known T-cell activation markers. Furthermore, the increase of intracellular IGFBP-2 seems to precede T-cell blast formation and all T cells in active phases of the cell cycle have high levels of IGFBP-2. Our results provide a basis for further investigations on the contribution of the IGF-system to the regulation of T-cell proliferation and differentiation. IGFBP-2, in particular, may have an important influence in the regulation of T-cell activation and proliferation.

Correlation of alpha-fetoprotein expression in normal hepatocytes during development with tyrosine phosphorylation and insulin receptor expression

The molecular mechanism of hepatic cell growth and differentiation is ill defined. In the present study, we examined the putative role of tyrosine phosphorylation in normal rat liver development and in an in vitro model, the alpha-fetoprotein-producing (AFP+) and AFP-nonproducing (AFP-) clones of the McA-RH 7777 rat hepatoma. We demonstrated in vivo and in vitro that the AFP+ phenotype is clearly associated with enhanced tyrosine phosphorylation, as assessed by immunoblotting and flow cytometry. Moreover, immunoprecipitation of proteins with anti-phosphotyrosine antibody showed that normal fetal hepatocytes expressed the same phosphorylation pattern as stable AFP+ clones and likewise for adult hepatocytes and AFP- clones. The tyrosine phosphorylation of several proteins, including the beta-subunit of the insulin receptor, insulin receptor substrate-1, p85 regulatory subunit of phosphatidylinositol-3-kinase, and ras-guanosine triphosphatase-activating protein, was observed in AFP+ clones, whereas the same proteins were not phosphorylated in AFP- clones. We also observed that fetal hepatocytes and the AFP+ clones express 4 times more of the insulin receptor beta-subunit compared with adult hepatocytes and AFP- clones and, accordingly, that these AFP+ clones were more responsive to exogenous insulin in terms of protein tyrosine phosphorylation. Finally, growth rate in cells of AFP+ clones was higher than that measured in cells of AFP- clones, and inhibition of phosphatidylinositol-3-kinase by LY294002 and Wortmannin blocked insulin- and serum-stimulated DNA synthesis only in cells of AFP+ clones. These studies provide evidences in support of the hypothesis that signaling via insulin prevents hepatocyte differentiation by promoting fetal hepatocyte growth.

Prognostic value of platelet-derived growth factor-A (PDGF-A) in gastric carcinoma

OBJECTIVE

Because our previous study indicated that PDGF-A mRNA expression in biopsy specimens might identify a subgroup of high-risk patients with gastric carcinoma, in this study we analyzed the prognostic value of platelet-derived growth factor-A (PDGF-A) gene expression in gastric carcinoma biopsy specimens.

METHODS

Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to analyze the PDGF-A gene expression in 65 gastric carcinoma endoscopic biopsy specimens. The 65 patients were divided into a PDGF-A-positive group (29 patients) and a PDGF-A-negative group (36 patients).

RESULTS

On the basis of 2-year follow-up data, the PDGF-A-positive group demonstrated a shorter overall survival rate compared with the PDGF-A-negative group (p < 0.0001). A similar correlation was found in 34 advanced-stage patients (p = 0.003) and in 24 advanced-stage patients who underwent a curative resection (p = 0.003). Multivariance analysis indicated that the transcription of PDGF-A gene is a potent prognostic factor that is independent of the traditional pathologic parameters.

CONCLUSIONS

Expression of PDGF-A mRNA in gastric biopsy specimens may be a new preoperative prognostic parameter in gastric carcinoma.

Characterization of growth factor responsiveness and alterations in growth factor homeostasis involved in the tumorigenic conversion of mouse oval cells

Five mouse oval cell lines were investigated in regards to their growth and differentiation factor (GDF) responsiveness and to changes in their GDF responsiveness following tumorigenic conversion. In all 59 GDFs and 11 comitogens were evaluated with variable responsiveness, depending on the mouse oval cell line under study, observed. Analysis of oval cell GDF responsiveness during tumorigenic conversion revealed that tumorigenic variants displayed alterations in GDF responsiveness which correlated with tumorigenicity. In addition, analysis of autocrine/paracrine growth factor production demonstrates that most tumorigenic variants produce growth factors. These studies demonstrate for the first time that (1) mouse oval cells respond to a wide variety of GDFs including various members of the interleukin, chemokine, stem cell factor, EGF, FGF, PDGF, TGF-beta, VEGF, insulin, CSF, TNF, HGF, and IFN growth and differentiation factor families in addition to multiple comitogens and (2) during tumorigenic conversion mouse oval cells undergo alterations which result in both alterations in GDF responsiveness and the autocrine/paracrine production of multiple GDFs.

Chondrocytes are regulated by cellular adhesion through CD44 and hyaluronic acid pathway

The articular cartilage consists of resident chondrocytes embedded within the extracellular matrix which contains several components such as collagen and hyaluronic acids (HA). CD44 is a major cell surface receptor for HA and is homologous to cartilage-link proteins. Although CD44 is present in cartilage, it is not clear if chondrocytes adhere to HA through CD44 or whether such adhesion changes the function of chondrocytes. We studied the molecular mechanisms of CD44-related chondrocyte adhesion to HA and the effects of such adhesion on chondrocyte function. Experiments were performed using the human chondrosarcoma-derived chondrocyte-like cell line HCS-2/8. Our results showed that (a) HCS-2/8 cells highly expressed CD44; (b) HCS-2/8 cells efficiently adhered to HA without any stimuli; (c) monoclonal antibody (mAb)-blocking studies indicated that adhesion of HCS-2/8 cells to HA was mainly mediated by the CD44/HA pathway; (d) cellular adhesion to HA increased the proliferation of HCS-2/8 cells, independent of transforming growth factor-beta (TGF-beta), but this was inhibited by CD44 mAb; (e) the adhesion of chondrocytes to HA also induced c-myc mRNA expression and this was also inhibited by CD44 mAb; and (f) the adhesion of cells to HA augmented TGF-beta mRNA expression, a process also reduced by CD44 mAb. Thus, HCS-2/8 cells effectively adhered to HA through cell surface CD44. The adhesion was also involved in cellular signaling which induced cellular proliferation and expression of c-myc mRNA as well as TGF-beta mRNA expression within the cells. Our results indicate that CD44 on chondrocytes plays an important role in normal and abnormal functions of cartilage through its adhesion to HA, which induces a variety of stimulatory signals to regulate chondrocyte proliferation as well as matrix synthesis in cartilage microenvironment.

Immunohistochemical analysis of platelet-derived growth factor and its receptors in fibrohistiocytic tumors

Platelet-derived growth factor (PDGF) is known to stimulate the proliferation of fibroblasts, although the role of PDGF and its receptors in the development of fibrohistiocytic tumors has not been clarified. In this study, we investigated this role by immunohistochemically staining PDGF and PDGF beta-receptors in paraffin-embedded dermatofibroma (DF), dermatofibrosarcoma protuberans (DFSP) and malignant fibrous histiocytoma (MFH) tissue. We also immunohistochemically investigated the relationship between PDGF beta-receptors and CD34, which is a known immunohistochemical marker for DFSP. Immunohistochemical studies using anti-PDGF-AA or BB antibodies showed that PDGF-AA and BB was found in 20 to 40% of the tumor cells in DF, DFSP, and MFH. No definite relationship for each tumor type was found. The expression of PDGF beta-receptors in DFSP and that of MFH tissue was significantly greater in comparison to DF and scar tissue. The expression of CD34 and PDGF beta-receptors in DFSP was observed in identical areas. These findings suggest that autocrine or paracrine growth stimulation, through PDGF beta-receptors, is related to the tumorous proliferation of fibrohistiocytic tumors, and the expression of PDGF beta-receptors might play a role in the proliferation of CD34 positive tumor cells.

Effect of suramin on human esophageal cancer cells in vitro and in vivo

BACKGROUND

Suramin disrupts several kinds of growth factor receptors. Since human esophageal squamous cell carcinoma expresses abundant epidermal growth factor receptors (EGFR) and proliferates in an autocrine and paracrine manner, it was expected that suramin inhibits tumor growth by disrupting EGFR.

METHODS

We studied the effect of suramin on the human esophageal squamous cell carcinoma cell line KEsC-II in vitro and in an animal model.

RESULTS

Cell proliferation was stimulated at a low concentration and inhibited at a high concentration of suramin in vitro. Since autophosphorylation of EGFR was stronger at the low concentration and weaker at the high concentration of suramin compared with the control, the effect of suramin was thought to be via phosphorylation of receptors. In the animal model tumor growth was significantly stimulated in the suramin-treated group compared with the control group, and the BrdU labeling index was also higher in the suramin-treated group.

CONCLUSIONS

As it was impossible to increase the dose of suramin intravenously because of side effects, administration of suramin by another method, such as subcutaneous injection around the tumor, may increase the concentration of suramin in the tumor tissue and promote the anti-tumor effect of suramin.

Dairy products and breast cancer: the IGF-I, estrogen, and bGH hypothesis

Research on the role of dietary factors in breast cancer causation has focused predominantly on fat intake. While some studies have examined associations between breast cancer rates and consumption of whole milk, there has been less attention given to dairy products in general. Dairy products contain both hormones and growth factors, in addition to fat and various chemical contaminants, that have been implicated in the proliferation of human breast cancer cells. This literature review evaluates the epidemiological and mechanistic evidence linking dairy consumption with breast cancer risk.

Autocrine transformation by fibroblast growth factor 9 (FGF-9) and its possible participation in human oncogenesis

Transfection of human fibroblast growth factor 9 (FGF-9) cDNA into mouse BALB/c 3T3 clone A31 cells led to morphological transformation of the cells and foci formation 4 weeks later. Isolated transformants had a higher saturation density than parental A31 cells, could grow in soft agar, and secreted FGF-9 into the culture supernatant. The introduction of FGF-9 N33 cDNA, which encodes a truncated protein that has 33 N-terminal amino acids deleted and has the same mitogenic potency as FGF-9, failed to lead to foci formation. Although FGF-9 is a secretory protein, it does not have a typical secretory signal sequence, and the secreted protein retains the full sequence coded in the cDNA except for the initiating methionine. The produced FGF-9 N33 was not secreted and remained within the cell. It is possible that FGF-9 has an uncleavable signal sequence within the first 33 N-terminal amino acids. All of the phenotypes acquired by transformation could be arrested by treatment with a neutralizing anti-human FGF-9 monoclonal antibody (MAb) 150-59. Additionally, transformants formed tumors in nude mice. Injection of MAb 150-59 suppressed tumor formation in nude mice and caused existing tumors to regress. Our results suggest that the cellular transformation mediated by FG F-9 is produced by autocrine stimulation. We have detected FGF-9 production in the human tumor cell lines glioma NMC-G1, from which FGF-9 was originally purified, and stomach carcinoma AZ-521. The growth of NMC-G1 was not affected by MAb 150-59, but that of AZ-521 was arrested by MAb 150-59 in the presence of heparin. Moreover, the growth of the AZ-521 cell tumor in nude mice could be partially arrested by antibody treatment. The possibility of a participation of FGF-9 in the formation of human tumors is suggested.

Alterations in epidermal growth factor binding to hepatic membranes following dietary exposure of rats to known hepatocarcinogens

Administration of the chemical carcinogen 2-acetylaminofluorene (2-AAF) has previously been shown to lower hepatic epidermal growth factor (EGF) binding levels during chemically induced hepatocarcinogenesis. To further characterize the specificity of this response, EGF binding levels for liver microsomes were determined after a 3-week administration of subacute doses of 2-AAF and five other known hepatocarcinogens: 3'-methyl-4-dimethylaminoazobenzene (3'Me-DAB), 2-AAF, aflatoxin B1 (AFB1), thioacetamide (TA), ethionine, benzidine (Benz), as well as four non-hepatocarcinogens: fluorene, p-aminoazobenzene, 4-acetylaminofluorene (4-AAF), and 3-methylcholanthrene. Five of six of the hepatocarcinogens tested (3'Me-DAB, 2-AAF, TA, AFB1 and Benz) caused significant lowering of EGF binding levels, and one of the four non-hepatocarcinogens (4-AAF) caused significant lowering of EGF binding levels. Paired feeding studies indicated that the decreases in EGF binding levels were not a result of differences in net diet consumption. These findings show that decreases in EGF binding capacity are caused by a diverse group of known hepatocarcinogenic compounds at an early stage in the carcinogenesis process.

Epithelial induction in dermatofibroma: a role for the epidermal growth factor (EGF) receptor

Dermatofibroma (DF) refers to a spectrum of firm, nodular, nonencapsulated lesions that occur commonly on the extremities. Histologically, DF is composed of spindle cells with variable differentiation toward histiocytic and vascular elements, often associated with epithelial hyperplasia and basilar keratinocyte pigmentation that histologically may simulate basal cell carcinoma (BCC). The characteristic epithelial changes are likely to be mesenchyma-mediated and probably represent a host reparative response otherwise known as the inductive phenomenon. Epidermal-mesenchymal cellular interactions, including induction, occur in various stages of embryonic skin development and in response to injury with tissue repair. Cellular interaction is mediated by direct apposition of cells or by soluble protein hormones produced directly by the cell (autocrine effect) or adjacent cells (paracrine effect). Among the important soluble mediators are epidermal growth factor (EGF), which is known to stimulate the proliferation and differentiation of a variety of transformed and benign tissues. We investigated the possible etiologic association between EGF receptor (EGF-R) expression and epithelial induction in a prospective series of 20 cases of DF compared to entities such as granular cell tumor, scar tissue, and nevus sebaceus similarly showing epithelial hyperplasia. Immunohistochemical staining for EGF-R showed strong dermal staining of dendritic spindle cells and overlying hyperplastic keratinocytes in each of the DF cases. Immunohistochemical staining for EGF-R was absent within all dermal loci of granular cell tumor (n = 3), nevus sebaceus (n = 6), and scar tissue (n = 12).

Autocrine growth induced by transferrin-like substance in bladder carcinoma cells

Ample evidence confirms that certain cancer cells have the capacity to produce multiple peptides as growth factors and that expression of their receptor may act in tumour cell paracrine and/or autocrine loop mechanisms, either by extracellular release of the growth factor or by the tumour itself. To study the possibility of an autocrine growth mechanism in bladder carcinoma, we investigated the ability of various bladder carcinoma cell lines to proliferate in serum-free medium. A rat bladder carcinoma cell line, BC47, demonstrated exponential and density-dependent growth in serum-free medium. Furthermore, conditioned medium from BC47 cells induced growth-stimulating activity for BC47 cells themselves. Purification and further characterization of this activity was performed by chromatographic methods, SDS-PAGE and N-terminal amino acid analysis. Finally, we have identified that a transferrin-like 70-kDa protein is found to be the main growth-promoting factor in this conditioned medium. In addition, specific antibodies against transferrin and the transferrin-receptor inhibit the in vitro growth of this cell line. Our data suggest that this transferrin-like factor possibly acts as an autocrine growth factor for cancer cells.

Growth Factors

Growth factors are polypeptides that interact with specific cellular receptors leading to many different biological responses. There are various families of growth factors that have similar biochemical structures. Although many growth factors stimulate cell proliferation, a few have primarily inhibitory functions, such as transforming growth factor-p (TGFB). Growth factors regulate various modes of action of endocrine tissues, including autocrine, paracrine, and endocrine functions. Recent studies have shown that growth factors also regulate various proteins in the cell cycle, and may have a direct or indirect effect on cell proliferation. For example, TGFB regulates various inhibitory cell-cycle proteins, including p27(kip1) and p15(INK4B). Molecular analyses of growth factors, including the cloning and sequencing of specific growth factor receptors, have contributed greatly to our understanding of the role these factors play in cellular homeostasis and neoplastic development.

Carcinogen-induced alteration in liver epidermal growth factor receptor distribution during the promotion stage of hepatocarcinogenesis in rat

Changes in hepatic membrane binding capacity for epidermal growth factor (EGF) were assessed during 2-acetylaminofluorine (2-AAF)-induced hepatocarcinogenesis. An overall decrease in membrane EGF binding levels was observed throughout the period of 2-AAF administration. Immunochemical studies indicated the decreases in EGF binding levels were paralleled by decreases in tissue EGF receptor levels. Immunohistochemical studies showed that the losses in hepatic EGF receptor levels were not uniform throughout the liver during the early, promotion stage of cancer development. During the promotion stage, preneoplastic liver nodules were found to display a higher level of EGF receptor than surrounding hepatic tissue. This resistance to 2-AAF-mediated down-regulation of EGF receptor may confer a proliferative advantage to the developing nodule relative to the surrounding liver tissue. Similar immunochemical and immunohistochemical analysis of hepatocarcinomas at late stages of 2-AAF-induced hepatocarcinogenesis indicated a uniform loss of EGF receptor in tumor and surrounding tissue. These studies indicate that carcinogen-mediated changes in EGF binding levels are different during the multistage process of hepatocarcinogenesis, and that resistance to down-regulation of EGF receptor among preneoplastic nodules may have a role in providing a selective growth advantage to initiated cell populations. EGF receptor may be useful as a dynamic marker assessing the development of hepatic tumors.