Transforming growth factor-beta 1 induces apoptosis through down-regulation of c-myc gene and overexpression of p27Kip1 protein in cervical carcinoma

Bone morphogenetic protein signaling is a possible therapeutic target in gynecologic cancer

Bone morphogenetic proteins (BMPs) belong to the transforming growth factor β (TGFβ) superfamily. BMPs play crucial roles in embryogenesis and bone remodeling. Recently, BMP signaling has been found to have diverse effects on different types of tumors. In this review, we summarized the effects of BMP signaling on gynecologic cancer. BMP signaling has tumor-promoting effects on ovarian cancer (OC) and endometrial cancer (EC), whereas it has tumor-suppressing effects on uterine cervical cancer (UCC). Interestingly, EC has frequent gain-of-function mutations in ACVR1, encoding one of the type I BMP receptors, which are also observed in fibrodysplasia ossificans progressiva and diffuse intrinsic pontine glioma. Little is known about the relationship between BMP signaling and other gynecologic cancers. Tumor-promoting effects of BMP signaling in OC and EC are dependent on the promotion of cancer stemness and epithelial-mesenchymal transition (EMT). In accordance, BMP receptor kinase inhibitors suppress the cell growth and migration of OC and EC. Since both cancer stemness and EMT are associated with chemoresistance, BMP signaling activation might also be an important mechanism by which OC and EC patients acquire chemoresistance. Therefore, BMP inhibitors are promising for OC and EC patients even if they become resistant to standard chemotherapy. In contrast, BMP signaling inhibits UCC growth in vitro. However, the in vivo effects of BMP signaling have not been elucidated in UCC. In conclusion, BMP signaling has a variety of functions, depending on the types of gynecologic cancer. Therefore, targeting BMP signaling should improve the treatment of patients with gynecologic cancer.

Eight Aging-Related Genes Prognostic Signature for Cervical Cancer

This study searched for aging-related genes (ARGs) to predict the prognosis of patients with cervical cancer (CC). All data were obtained from Molecular Signatures Database, Cancer Genome Atlas, Gene Expression Integration, and Genotype Organization Expression. The R software was used to screen out the differentially expressed ARGs (DE-ARGs) between CC and normal tissues. A protein-protein interaction network was established by the DE-ARGs. The univariate and multivariate Cox regression analyses were conducted on the first extracted Molecular Complex Detection component, and a prognostic model was constructed. The prognostic model was further validated in the testing set and GSE44001 dataset. Prognosis was analyzed by Kaplan-Meier curves, and accuracy of the prognostic model was assessed by receiver operating characteristic area under the curve analysis. An independent prognostic analysis of risk score and some clinicopathological factors of CC was also performed. The copy-number variant (CNV) and single-nucleotide variant (SNV) of prognostic ARGs were analyzed by the BioPortal database. A clinical practical nomogram was established to predict individual survival probability. Finally, we carried out cell experiment to further verify the prognostic model. An eight-ARG prognostic signature for CC was constructed. High-risk CC patients had significantly shorter overall survival than low-risk patients. The receiver operating characteristic (ROC) curve validated the good performance of the signature in survival prediction. The Figo_stage and risk score served as independent prognostic factors. The eight ARGs mainly enriched in growth factor regulation and cell cycle pathway, and the deep deletion of FN1 was the most common CNV. An eight-ARG prognostic signature for CC was successfully constructed.

Liposomal honokiol promotes hair growth via activating Wnt3a/β-catenin signaling pathway and down regulating TGF-β1 in C57BL/6N mice

Liposomal honokiol isolated from the genus Magnolia has been found to have antiangiogenic, anti-inflammatory and antitumor properties. However, there has no report on its role in hair growth. Hair follicles are life-long cycled organelles that go through from anagen, catagen and telogen stages and are regulated by diverse signaling pathways, including Wnt/β-catenin, Notch, Epidermal growth factor (EGF) and Sonic hegehog (SHH). Wnt signals are essential for the initiation of hair follicle placode development and a new potential target of hair loss treatment. This study was designed to investigate the effect of liposomal honokiol (Lip-honokiol) on inducing hair anagen. We identified the hair grew out in advance in the shaving area of C57BL/6N mice after the treatment of liposomal honokiol (Lip-honokiol) by daily abdominal injection. We first demonstrated that Lip-Honokiol activated the Wnt3a/β-catenin pathway and downregulated the transforming growth factor-β1 (TGF-β1) to promote hair growth in mice via immunohistochemistry and immunofluorescence staining. These findings suggest that Lip-honokiol activated the Wnt/β-catenin pathway and accelerated the transfer from the telogen to anagen stage and finally promoted the hair growth.

The Interaction Between Human Papillomaviruses and the Stromal Microenvironment

Human papillomaviruses (HPVs) are small, double-stranded DNA viruses that replicate in stratified squamous epithelia and cause a variety of malignancies. Current efforts in HPV biology are focused on understanding the virus-host interactions that enable HPV to persist for years or decades in the tissue. The importance of interactions between tumor cells and the stromal microenvironment has become increasingly apparent in recent years, but how stromal interactions impact the normal, benign life cycle of HPVs, or progression of lesions to cancer is less understood. Furthermore, how productively replicating HPV impacts cells in the stromal environment is also unclear. Here we bring together some of the relevant literature on keratinocyte-stromal interactions and their impacts on HPV biology, focusing on stromal fibroblasts, immune cells, and endothelial cells. We discuss how HPV oncogenes in infected cells manipulate other cells in their environment, and, conversely, how neighboring cells may impact the efficiency or course of HPV infection.

Transforming growth factor-β1 in carcinogenesis, progression, and therapy in cervical cancer

Transforming growth factor β1 (TGF-β1) is a multifunctional cytokine that plays important roles in cervical tumor formation, invasion, progression, and metastasis. TGF-β1 functions as a tumor inhibitor in precancerous lesions and early stage cancers of cervix whereas as a tumor promoter in later stage. This switch from a tumor inhibitor to a tumor promoter might be due to various alterations in TGF-β signaling pathway, such as mutations or loss of expression of TGF-β receptors and SMAD proteins. Additionally, the oncoproteins of human papillomaviruses have been shown to stimulate TGF-β1 expression, which in turn suppresses host immune surveillance. Thus, in addition to driving tumor cell migration and metastasis, TGF-β1 is believed to play a key role in promoting human papillomavirus infection by weakening host immune defense. In this article, we will discuss the role of TGF-β1 in the expression, carcinogenesis, progression, and therapy in cervical cancers. A better understanding of this cytokine in cervical carcinogenesis is essential for critical evaluation of this cytokine as a potential prognostic marker and therapeutic target.

Mesenchymal stromal cells derived from cervical cancer tumors induce TGF-β1 expression and IL-10 expression and secretion in the cervical cancer cells, resulting in protection from cytotoxic T cell activity

Cervical cancer (CeCa) tumors are characterized by increased expression of TGF-β1 and IL-10, which are correlated with downregulated expression of major histocompatibility complex class I antigens (HLA-I) on cancer cells and a reduced immune response mediated by cytotoxic T lymphocytes (CTLs). Mesenchymal stromal cells (MSCs) are important components in the tumor microenvironment that have been suggested to contribute to cancer progression through the induction of TGF-β1 and IL-10. In this study, we provided evidence that MSCs derived from cervical tumors (CeCa-MSCs) cocultured with CeCa cells induced significant expression of TGF-β1 and secretion of IL-10 by CeCa cells compared to MSCs derived from the normal cervix (NCx-MSCs) and normal bone marrow (BM-MSCs; gold standard). This increase in expression was associated with a significant downregulation of HLA-I molecules and protection of the cells against specific CTL lysis. Interestingly, the addition of the neutralizing antibody anti-TGF-β to the CeCa/CeCa-MSCs coculture strongly inhibited the expression and production of IL-10 by CeCa cells. Anti-TGF-β as well as anti-IL-10 also abolished HLA-I downregulation, and reversed the inhibition of CTL cytotoxicity. These results provide evidence that TGF-β1 and IL-10 could play an important role in the downregulation of HLA-I molecules on CeCa cells induced by tumor MSCs. Our findings suggest a novel mechanism through which MSCs may protect tumor cells from immune recognition by specific CTLs.

Effect of LSKL peptide on thrombospondin 1-mediated transforming growth factor β signal activation and liver regeneration after hepatectomy in an experimental model

Background

A strategy for accelerating liver regeneration after hepatectomy would offer great benefits in preventing postoperative liver failure and improving surgical outcomes. Transforming growth factor (TGF) β is a potent inhibitor of hepatocyte proliferation. Recently, thrombospondin (TSP) 1 has been identified as a negative regulator of liver regeneration by activation of local TGF-β signals. This study aimed to clarify whether the LSKL (leucine–serine–lysine–leucine) peptide, which inhibits TSP-1-mediated TGF-β activation, promotes liver regeneration after hepatectomy in mice.

Methods

Mice were operated on with a 70 per cent hepatectomy or sham procedure. Operated mice received either LSKL peptide or normal saline intraperitoneally at abdominal closure and 6 h after hepatectomy. Perioperative plasma TSP-1 levels were measured by enzyme-linked immunosorbent assay in patients undergoing hepatectomy.

Results

Administration of LSKL peptide attenuated Smad2 phosphorylation at 6 h. S-phase entry of hepatocytes was accelerated at 24 and 48 h by LSKL peptide, which resulted in faster recovery of the residual liver and bodyweight. Haematoxylin and eosin tissue staining and blood biochemical examinations revealed no significant adverse effects following the two LSKL peptide administrations. In the clinical setting, plasma TSP-1 levels were lowest on the first day after hepatectomy. However, plasma TSP-1 levels at this stage were significantly higher in patients with subsequent liver dysfunction compared with levels in those without liver dysfunction following hepatectomy.

Conclusion

Only two doses of LSKL peptide during the early period after hepatectomy can promote liver regeneration. The transient inhibition of TSP-1/TGF-β signal activation using LSKL peptide soon after hepatectomy may be a promising strategy to promote subsequent liver regeneration.

Metformin targets c-MYC oncogene to prevent prostate cancer

Prostate cancer (PCa) is the second leading cause of cancer-related death in American men and many PCa patients develop skeletal metastasis. Current treatment modalities for metastatic PCa are mostly palliative with poor prognosis. Epidemiological studies indicated that patients receiving the diabetic drug metformin have lower PCa risk and better prognosis, suggesting that metformin may have antineoplastic effects. The mechanism by which metformin acts as chemopreventive agent to impede PCa initiation and progression is unknown. The amplification of c-MYC oncogene plays a key role in early prostate epithelia cell transformation and PCa growth. The purpose of this study is to investigate the effect of metformin on c-myc expression and PCa progression. Our results demonstrated that (i) in Hi-Myc mice that display murine prostate neoplasia and highly resemble the progression of human prostate tumors, metformin attenuated the development of prostate intraepithelial neoplasia (PIN, the precancerous lesion of prostate) and PCa lesions. (ii) Metformin reduced c-myc protein levels in vivo and in vitro. In Myc-CaP mouse PCa cells, metformin decreased c-myc protein levels by at least 50%. (iii) Metformin selectively inhibited the growth of PCa cells by stimulating cell cycle arrest and apoptosis without affecting the growth of normal prostatic epithelial cells (RWPE-1). (iv) Reduced PIN formation by metformin was associated with reduced levels of androgen receptor and proliferation marker Ki-67 in Hi-Myc mouse prostate glands. Our novel findings suggest that by downregulating c-myc, metformin can act as a chemopreventive agent to restrict prostatic neoplasia initiation and transformation.

SUMMARY

Metformin, an old antidiabetes drug, may inhibit prostate intraepithelial neoplasia transforming to cancer lesion via reducing c-MYC, an 'old' overexpressed oncogene. This study explores chemopreventive efficacy of metformin in prostate cancer and its link to cMYC in vitro and in vivo.

Expression and mutational analysis of TGF-beta/Smads signaling in human cervical cancers

OBJECTIVE

To define the molecular basis of TGF-beta1 function in cervical carcinogenesis, we explored the expression and mutational status of TGF-beta1, TGF-beta1 receptors, and Smads, the regulators of the TGF-beta1 signaling pathway, in human cervical cancers.

METHODS

Expression of TGF-beta1, TGF-beta1 receptors, and Smads transcripts were determined by quantitative reverse transcription-polymerase chain reaction (RT-PCR), and sequence alteration was analyzed using RT-PCR-single-strand conformation polymorphism (SSCP) analysis. Genomic levels of TGF-beta1, TGF-beta1 receptors and Smads was also measured by quantitative genomic PCR.

RESULTS

Abnormal overexpression of TGF-beta1 and abnormal reduction of type II TGF-beta1 receptor were identified in 36% (18 of 50) and 20% (10 of 50) of cervical cancer tissues, respectively. 22% (11 of 50) in Smad2 and 14% (7 of 50) in Smad4 revealed tumor specific mRNA reduction less than a half of normal means. In addition, no evidence for sequence alterations of the gene was found by RT-PCR-SSCP analysis.

CONCLUSION

Our study demonstrates that disruption of TGF-beta/Smad signaling pathway exist in human cervical cancer, suggesting that abnormal expressions of the member of TGF-beta/Smad signaling pathway might contribute to the malignant progression of human cervical tumors via suppressing the tumor suppression function of TGF-beta1 1's tumor suppression function.

Down-regulation of transforming growth factor-beta type II receptor (TGF-betaRII) protein and mRNA expression in cervical cancer

BACKGROUND

Cervical carcinogenesis is a multistep process initiated by "high risk" human papillomaviruses (HR-HPV), most commonly HPV16. The infection per se is, however, not sufficient to induce malignant conversion. Transforming Growth Factor beta (TGF-beta) inhibits epithelial proliferation and altered expression of TGF-beta or its receptors may be important in carcinogenesis. One cofactor candidate to initiate neoplasia in cervical cancer is the prolonged exposure to sex hormones. Interestingly, previous studies demonstrated that estrogens suppress TGF-beta induced gene expression. To examine the expression of TGF-beta2, TGF-betaRII, p15 and c-myc we used in situ RT-PCR, real-time PCR and immunohistochemistry in transgenic mice expressing the oncogene E7 of HPV16 under control of the human Keratin-14 promoter (K14-E7 transgenic mice) and nontransgenic control mice treated for 6 months with slow release pellets of 17beta-estradiol.

RESULTS

Estrogen-induced carcinogenesis was accompanied by an increase in the incidence and distribution of proliferating cells solely within the cervical and vaginal squamous epithelium of K14-E7 mice. TGF-beta2 mRNA and protein levels increased in K14-E7 transgenic mice as compared with nontransgenic mice and further increased after hormone-treatment in both nontransgenic and transgenic mice. In contrast, TGF-betaRII mRNA and protein levels were decreased in K14-E7 transgenic mice compared to nontransgenic mice and these levels were further decreased after hormone treatment in transgenic mice. We also observed that c-myc mRNA levels were high in K14-E7 mice irrespective of estrogen treatment and were increased in estrogen-treated nontransgenic mice. Finally we found that p15 mRNA levels were not increased in K14-E7 mice.

CONCLUSION

These results suggest that the synergy between estrogen and E7 in inducing cervical cancer may in part reflect the ability of both factors to modulate TGF-beta signal transduction.

Effects of human papillomavirus type 16 E7 protein on the growth of cervical carcinoma cells and immuno-escape through the TGF-beta1 signaling pathway

OBJECTIVE

E7 is regarded as one of the main oncoproteins of high-risk human papillomaviruses (HPVs). It may affect the transforming growth factor beta 1 (TGF-beta1) signaling pathway. In this study, the relationship between HPV-16 infection and the functions of three critical factors of the TGF-beta1/Smads pathway was explored to assess the possible role of E7 in the development of cervical cancer.

METHODS

The expression of E7, TGF-beta1, TbetaR-II and Smad4 was detected by immunohistochemistry in paraffin-embedded cervical samples, and by RT-PCR and Western blotting in cervical cancer cell lines. The effect of TGF-beta1 on the growth of cervical cancer cells were tested by methyl thiazolyl tetrazolium (MTT), and the effects of HPV-16 E7 protein on normal and malignant cervical cells were investigated by flow cytometry.

RESULTS

During the progression from benign to malignant lesions, the expression levels of TGF-beta1 and Smad4 increased significantly in cervical carcinoma tissues. The expression of TGF-beta1 was positively correlated with E7 expression. In vitro experiments showed that TGF-beta1 could not inhibit the proliferation of several cervical carcinoma cell lines in long-term regulation, but could inhibit immunologic reactions of peripheral blood mononuclear cells (PBMCs). Blocking E7 expression could lower the expression level of TGF-beta1 and induce cells to enter apoptosis.

CONCLUSIONS

Our data indicate that HPV-16 E7 protein plays an important role during the development of cervical cancer by immuno-inhibition and stimulation of tumor cell proliferation through the TGF-beta1/Smads signaling pathway.

Reciprocal control of Forkhead box O 3a and c-Myc via the phosphatidylinositol 3-kinase pathway coordinately regulates p27Kip1 levels

B cell receptor (BCR) engagement of murine WEHI 231 immature B lymphoma cells leads sequentially to a drop in NF-kappa B and c-Myc, and induction of the p27(Kip1) cyclin-dependent kinase inhibitor, which promotes growth arrest and apoptosis. BCR engagement was recently shown to induce a drop in phosphatidylinositol 3-kinase (PI3K)/Akt signaling, preceding the increase in p27. As induction of p27 is due to an increase in gene transcription, we investigated the role of the Forkhead box O (FOXO) transcription factor family, which has been shown to potently induce p27 promoter activity. We demonstrate that pharmacologic inhibitors of PI3K or BCR engagement lead to decreased inactive cytoplasmic levels and increased active functional nuclear FOXO3a. In contrast, inhibition of PI3K/Akt signaling decreased the levels of NF-kappa B and c-Myc, which has been shown to repress p27 promoter activity. To test the effects of ectopic c-Myc on endogenous p27 levels, WEHI 231 cells stably expressing c-Myc or empty vector DNA were prepared. Ectopic c-Myc blocked the induction of p27 expression upon either inhibition of PI3K or BCR engagement. Thus, p27(Kip1) is coordinately regulated via two arms of a signaling pathway that are inversely controlled upon inhibition of PI3K: induction of the activator FOXO3a and down-regulation of the repressor c-Myc.

Estradiol reverses TGF-beta1-induced mesangial cell apoptosis by a casein kinase 2-dependent mechanism

BACKGROUND

The slower rate of progression of chronic renal disease in women than in men is explained in part by the ability of estradiol to reverse the stimulatory effect of transforming growth factor-beta1 (TGF-beta1) on collagen IV synthesis at the level of casein kinase 2 activation. Casein kinase 2 also phosphorylates and activates the pro-apoptotic protein, p53. We hypothesized that estradiol would reverse TGF-beta1-induced mesangial cell apoptosis by antagonizing the stimulatory effects of TGF-beta1 on casein kinase 2 activity, thereby preventing p53 activation.

METHODS

The effects of TGF-beta1 on mesangial cell apoptosis, p53 phosphorylation, Bax and Bcl-2 levels, caspase 9 activity, and cleavage of PARP were examined. The abilities of estradiol and a specific inhibitor of CK2 (5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole) (DRB) to modulate the effects of TGF-beta1 on these processes were also examined.

RESULTS

TGF-beta1 (2 ng/mL), which up-regulates CK2 activity, induces apoptosis in murine mesangial cells together with p53 serine389 phosphorylation, up-regulation of Bax, suppression of Bcl-2, destabilization of mitochondrial permeability transition pores, stimulation of caspase 9 activity and activation of PARP. TGF-beta1-induced p53 activation and all the intermediary steps leading to mesangial cell apoptosis were reversed by estradiol (10-9 mol/L) and by DRB, potent inhibitors of CK2 activity, but not by inhibitors of the p38 MAPK, ERK or JNK signaling cascades. In contrast, TGF-beta1 failed to induce apoptosis in p53 knockout mesangial cells.

CONCLUSIONS

Our data suggest that CK2 mediates the stimulatory effects of TGF-beta1 on mesangial cell apoptosis via a p53-dependent mechanism. The ability of estradiol to reverse TGF-beta1-induced apoptosis may contribute to the protective effects of female gender on the course of chronic renal disease.

Polymorphism in codons 10 and 25 of the transforming growth factor-beta 1 (TGF-beta1) gene in patients with invasive squamous cell carcinoma of the uterine cervix

Transforming growth factor-beta 1 (TGF-beta1) has a multifactorial role in the development of cervical cancer. It potently inhibits the growth of epithelial cells that harbour oncogenic human papilloma viruses (HPVs). TGF-beta1 also inhibits the expression of the early viral transforming regions E6 and E7, which appear to be the key oncoproteins. It has been suggested that squamous cell carcinomas are devoid of TGF-beta1, raising the possibility that elevated levels of this growth factor could protect against cervical cancer. It is also recognized that the production and levels of TGF-beta1 are genetically predetermined and individually variable. Two genetic polymorphisms in the DNA encoding the leader sequence of the TGF-beta1 gene have been described and shown to be associated with the production of high or low TGF-beta1 levels in vivo and in vitro. We hypothesized that the inheritance of these polymorphisms could influence the development of invasive cervical cancer. This hypothesis was investigated by studying polymorphism in codons 10 and 25 of the TGF-beta1 gene. We studied 97 patients with invasive cervical cancer and 73 healthy controls and found that the distributions of alleles T (Leu) and/or C (Pro) and alleles G (Arg) and/or C (Pro) in codons 10 and 25, respectively, were similar. There was no significant association between the alleles and the histological degree of cancer differentiation. It appears that the role of this growth factor in cervical oncogenesis is not related to the point mutations that we examined in codons 10 and 25 of the TGF-beta1 gene. We speculate that other factors, including additional polymorphisms of the TGF-beta1 gene, the status of TGF-beta1 receptors, the complex cytokine network, differential responsiveness of cells to the stimuli, and the status of the precancer/cancer genome, may play a role in development of invasive cervical cancer.

TGF-beta 1 as an enhancer of Fas-mediated apoptosis of lung epithelial cells

Transforming growth factor-beta 1 (TGF-beta 1) has important roles in lung fibrosis and the potential to induce apoptosis in several types of cells. We previously demonstrated that apoptosis of lung epithelial cells induced by Fas ligation may be involved in the development of pulmonary fibrosis. In this study, we show that TGF-beta1 induces apoptosis of primary cultured bronchiolar epithelial cells via caspase-3 activation and down-regulation of cyclin-dependent kinase inhibitor p21. Concentrations of TGF-beta 1 that were not sufficient to induce apoptosis alone could enhance agonistic anti-Fas Ab or rFas ligand-mediated apoptosis of cultured bronchiolar epithelial cells. Soluble Fas ligand in the bronchoalveolar lavage fluid (BALF) from patients with idiopathic pulmonary fibrosis (IPF) also induced apoptosis of cultured bronchiolar epithelial cells that was significantly attenuated by anti-TGF-beta Ab. Otherwise, BALF from patients with hypersensitivity pneumonitis (HP) could not induce apoptosis on bronchiolar epithelial cells, despite its comparable amounts of soluble Fas ligand. The concentrations of TGF-beta 1 in BALF from patients with IPF were significantly higher compared with those in BALF from patients with HP or controls. Furthermore, coincubation with the low concentration of TGF-beta 1 and HP BALF created proapoptotic effects comparable with the IPF BALF. In vivo, the administration of TGF-beta 1 could enhance Fas-mediated epithelial cell apoptosis and lung injury via caspase-3 activation in mice. Our results demonstrate a novel role of TGF-beta 1 in the pathophysiology of pulmonary fibrosis as an enhancer of Fas-mediated apoptosis of lung epithelial cells.

The molecular biology of cervical cancer

Cervical cancer remains a major worldwide health problem, especially in developing countries. Over the last few decades many advancements have been made in determining the molecular genetics of the development of cancer. This paper attempts to summarize the major disturbances in cellular function known to date to play a role in the development of cervical cancer. The role of human papillomavirus (HPV) infection in the development of cervical cancer is a major player in the genetic abnormalities described thus far. The effects of HPV E6 and E7 on important cell cycle genes are discussed. As oncogenes and tumor suppressor genes have been described in the different types of cancer, their possible role in cervical cancer has been investigated. The possible role of angiogenesis and angiogenic factors is described. Because of the importance of HPV infection in the development of cervical cancer, the role of the body's immune function in this cancer is also under study, and the results of these findings are summarized. Although a complete paradigm of the development of cervical cancer from normal cervical epithelium is not yet known, continued study in this area will hopefully lead to a defined progression of molecular and immunologic abnormalities that cause the disease. The goal would be to use this information to help prevent and/or treat cervical cancer in the future.

Expression of growth factors, growth factor receptors and apoptosis related proteins in invasive breast cancer: relation to apoptotic rate

PURPOSE

To assess the relation between growth factors, growth-factor receptors, p53, bcl-2 and bax expression, and the rate of apoptosis in invasive breast cancer patients.

MATERIALS AND METHODS

Tumors from 45 patients were assessed by immunohistochemistry for expression patterns of five growth factors and their receptors; platelet-derived growth factor A chain (PDGF-AA) and PDGF-receptor alpha (PDGFalphaR), PDGF-BB and PDGFbetaR, transforming growth-factor alpha (TGFalpha) and its receptor-epidermal growth factor receptor (EGFR) and vascular-endothelial growth factor (VEGF) and its receptors vascular-endothelial growth factor receptor I (FLT-1) and vascular-endothelial growth factor receptor II (FLK-1/KDR), two growth-inhibiting factors; transforming-growth factor beta I (TGFbeta1) and TGFbeta2 and their receptor couple TGFbeta receptor I (TGFbetaR-I) and TGFbetaR-II, and basic-fibroblast growth factor (bFGF). Besides, the expression patterns of the bcl-2, bax and p53 gene products were investigated. Expression patterns were correlated to the number of apoptotic cells assessed by light microscopy.

RESULTS

PDGF-BB and bFGF showed a positive correlation with the AI (p = 0.006 and p = 0.030, respectively). EGFR expression was associated with a high number of apoptotic cells but did not reach significance (p = 0.10). None of the other individual growth factors, growth-inhibiting factors or receptors showed a significant relation with the AI. The presence of a possible auto- or paracrine loop of the TGFalpha/EGFR combination was associated with a high number of apoptotic cells but did not reach significance (p = 0.20). PDGF-AA, bFGF and EGFR expression showed a significant relation to p53 overexpression. TGFbeta2 expression showed an inverse correlation with p53 overexpression.

CONCLUSION

We found an association between several growth factors and growth-factor receptors with number of apoptotic cells. This underlines the importance of growth factors and their receptors not just in proliferation, but also, directly and/or indirectly, in regulating the rate of apoptosis in invasive breast cancer. Growth factors and their receptors may therefore be useful as targets of anti-cancer therapy by inducing apoptosis or increasing the sensitivity of cells for chemo- or hormonal therapy induced apoptosis.

Cyclin A down-regulation in TGFbeta1-arrested follicular lymphoma cells

Transforming growth factor beta1 (TGFbeta1) induces growth arrest in many cell types, including B lymphocytes. We examined the effect of TGF on cell cycle progression of a non-Hodgkin lymphoma cell line of follicular lymphoma subtype (FL). After 48 h of TGFbeta1 (10 ng/ml) treatment, a significantly increased number of DoHH2 cells was retained in G(0)/G(1) phase. We examined the level of cell cycle components, cyclins, cyclin-dependent kinases (cdk), and their inhibitors. We found that the expression of cyclin A and p21(WAF1) molecules was primarily modulated by TGFbeta1 treatment while the expression of other regulatory components, like cyclins D, cyclin E, cdk2, cdk4, and cdk6 or p15(INK4B), p16(INK4A), and p27(KIP1) was not significantly affected. We further examined expression and activity of CREB/ATF family members to examine their roles in cyclin A inhibition. The binding activity of CREB-1 and ATF-2 to the CRE region of the cyclin A promoter was almost completely abolished due to the treatment. The total level of CREB-1, ATF-2, and ATF-3 was notably reduced. Moreover, CREB-1 was dephosphorylated due to the treatment as revealed by immunoblotting. We assume that down-regulation of cyclin A was mediated by the absence of CREB/ATF activation dimers. The profound effect on the ATF family of transcription factors indicates the complexity of TGFbeta1 action on FL B malignant cells.

Role of apoptosis and transforming growth factor beta1 in fibroblast selection and activation in systemic sclerosis

OBJECTIVE

We hypothesized that pathophysiologic events during the development of systemic sclerosis (SSc) may lead to selection and propagation of certain apoptosis-resistant fibroblast subpopulations. The aim of this study was to examine a possible role for apoptosis in fibroblast selection in SSc and the role of transforming growth factor beta1 (TGFbeta1).

METHODS

We compared SSc and normal fibroblasts for their susceptibility to anti-Fas-induced apoptosis and analyzed 2 models that might lead to fibroblast resistance to apoptosis in this process: long-term exposure to either anti-Fas or TGFbeta1.

RESULTS

SSc-derived fibroblasts were resistant to anti-Fas-induced apoptosis, showing 5.5 +/- 17.2% (mean +/- SD) apoptosis, compared with 32.1 +/- 14.0% among normal fibroblasts (P < 0.05). Anti-Fas-selected normal fibroblasts showed 9.0 +/- 3.7% apoptosis, compared with 21.6 +/- 5.9% for sham-treated cells, which is consistent with the elimination of apoptosis-susceptible subpopulations. Normal fibroblasts subjected to 6 weeks of TGFbeta1 treatment showed not only resistance to apoptosis, but also proliferation (118.5 +/- 35.4%), after anti-Fas treatment, compared with sham-treated cells (35.1 +/- 11.1% apoptotic cell death). TGFbeta1 treatment also increased the proportion of myofibroblasts (47% versus 28% in controls). Cultured SSc fibroblasts had a greater proportion of myofibroblasts (32-83%) than did normal fibroblasts (4-25%). We also examined the relationship between collagen gene expression and the myofibroblast phenotype in normal and SSc skin sections. Only 2 of 7 normal sections had alpha-smooth muscle actin (a-SMA)-positive cells (mean +/- SD score 0.29 +/- 0.49 on a scale of 0-3), but all SSc sections were positive for alpha-SMA, with a mean score of 1.90 +/- 0.88 for lesional and 1.50 +/- 0.71 for nonlesional sections. Scores for alpha1(I) procollagen messenger RNA (mRNA) in lesional skin (mean +/- SD 3.30 +/- 0.82 on a scale of 1-4) were significantly higher than in normal (1.43 +/- 0.79) or nonlesional (1.40 +/- 0.52) skin, but scores varied, and there was no correlation between collagen mRNA and alpha-SMA levels.

CONCLUSION

Our results show that resistance to apoptosis is an important part of the SSc phenotype. TGFbeta1 may play a role by inducing apoptosis-resistant fibroblast populations, and also by inducing myofibroblasts and by enhancing extracellular matrix synthesis.

Apoptosis induced by TGF-beta 1 in Burkitt's lymphoma cells is caspase 8 dependent but is death receptor independent

TGF-beta is a potent inducer of apoptosis in many Burkitt's lymphoma (BL) cell lines. In this study, we characterize this apoptotic process in the EBV-negative BL41 cell line. Induction of apoptosis was detected as early as 8 h after TGF-beta treatment, as assayed by TUNEL and poly(ADP-ribose) polymerase cleavage. FACS analysis demonstrates that this proceeds predominately from the G1, but also from the G2/M phases of the cell cycle. We observed no early detectable changes in the steady-state levels of Bcl-2 and several of its family members after TGF-beta treatment. We detected cleavage of caspases 2, 3, 7, 8, and 9 into their active subunits. Consistent with the involvement of these enzymes in TGF-beta-mediated apoptosis, the broad spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(Ome)-flouromethylketone (ZVAD-fmk) blocked TGF-beta-induced apoptosis and revealed a G1 arrest in treated cells. Use of specific caspase inhibitors revealed that the induction of apoptosis is caspase 8 dependent, but caspase 3 independent. Activation of caspase 8 has been shown to be a critical event in death receptor-mediated apoptosis. However, TGF-beta treatment of BL41 cells was found not to affect the cell surface expression of Fas, TNF-R1, DR3, DR4, or DR5, or the steady-state expression levels of Fas ligand, TNF-R1, DR3, DR4, and DR5. Furthermore, blocking experiments indicated that TGF-beta-mediated apoptosis is not dependent on Fas ligand, TNF-alpha, tumor necrosis-like apoptosis-inducing ligand, or TNF-like weak inducer of apoptosis signaling. Therefore, it appears that TGF-beta induces apoptosis in BL cell lines via caspase 8 in a death receptor-independent fashion.

Contact with fibrillar collagen inhibits melanoma cell proliferation by up-regulating p27KIP1

It is known that the extracellular matrix regulates normal cell proliferation, and it is assumed that anchorage-independent malignant cells escape this regulatory function. Here we demonstrate that human M24met melanoma cells remain responsive to growth regulatory signals that result from contact with type I collagen and that the effect on proliferation depends on the physical structure of the collagen. On polymerized fibrillar collagen, M24met cells are growth arrested at the G(1)/S checkpoint and maintain high levels of p27(KIP1) mRNA and protein. In contrast, on nonfibrillar (denatured) collagen, the cells enter the cell cycle, and p27(KIP1) is down-regulated. These growth regulatory effects involve contact between type I collagen and the collagen-binding integrin alpha(2)beta(1), which appears restricted in the presence of fibrillar collagen. Thus melanoma cells remain sensitive to negative growth regulatory signals originating from fibrillar collagen, and the proteolytic degradation of fibrils is a mechanism allowing tumor cells to escape these restrictive signals.

Endocervical cancer is associated with an increase in the ligands and receptors for transforming growth factor-beta and a contrasting decrease in p27(Kip1)

OBJECTIVE

The aim of this study was to investigate the relationship between the expression of the TGF-beta ligands and TGF-beta receptors to the expression of p27(Kip1), a TGF-beta-regulated gene, in endocervical cancer.

METHODS

To examine the expression of TGF-beta and p27(Kip1) in malignant transformation of the uterine endocervix, a panel of 23 formalin-fixed and paraffin-embedded human cervical specimens, including 8 with benign endocervical glands, 8 with cervical adenocarcinoma in situ, and 7 with cervical adenocarcinomas, was used. Tissues were immunostained with polyclonal antibodies that react specifically with TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-beta RI, TGF-beta RII, and p27(Kip1).

RESULTS

Immunostaining for TGF-beta 1, TGF-beta 2, TGF-beta 3, TGF-beta RI, TGF-beta RII, and p27(Kip1) was detected in normal endocervix, with the TGF-betas showing weak cytoplasmic staining, while p27(Kip1) showed strong nuclear staining. Expression of TGF-beta increased significantly upon neoplastic transformation with the TGF-beta ligands and receptors showing strong cytoplasmic staining in adenocarcinoma in situ compared to normal endocervix. Interestingly, expression of TGF-beta was lower in adenocarcinoma than in adenocarcinoma in situ, but still significantly higher than in normal endocervix. TGF-beta 2 and TGF-beta 3 showed higher levels of immunostaining than TGF-beta 1 in adenocarcinomas. In contrast, p27(Kip1) protein expression decreased with progressive malignancy, with lower p27(Kip1) protein levels detected in adenocarcinoma than in adenocarcinoma in situ, while normal endocervix showed the highest level of p27(Kip1) protein expression.

CONCLUSION

Elevated expression of the TGF-beta ligands and receptors is found in both cervical adenocarcinoma in situ and adenocarcinoma compared to normal endocervix. In contrast, a progressive decrease in p27(Kip1) occurs upon neoplastic transformation of the normal endocervix to cervical adenocarcinoma. These results suggest that neoplastic transformation of the endocervix may be related to dysregulation of TGF-beta and p27(Kip1) seen as an elevation of TGF-beta and a reduction of p27(Kip1) expression that may lead to loss of cell cycle control.

Protooncogenes as mediators of apoptosis

Apoptosis has been well established as a vital biological phenomenon that is important in the maintenance of cellular homeostasis. Three major protooncogene families and their encoded proteins function as mediators of apoptosis in various cell types and are the subject of this chapter. Protooncogenic proteins such as c-Myc/Max, c-Fos/c-Jun, and Bcl-2/Bax utilize a synergetic effect to enhance their roles in the pro- or antiapoptotic action. These family members activate and repress the expression of their target genes, control cell cycle progression, and execute programmed cell death. Repression or overproduction of these protooncogenic proteins induces apoptosis, which may vary as a result of either cell type specificity or the nature of the apoptotic stimuli. The proapoptotic and antiapoptotic proteins exert their effects in the membrane of cellular organelles. Here they generate cell-type-specific signals that activate the caspase family of proteases and their regulators for the execution of apoptosis.

Control of murine hair follicle regression (catagen) by TGF-beta1 in vivo

The regression phase of the hair cycle (catagen) is an apoptosis-driven process accompanied by terminal differentiation, proteolysis, and matrix remodeling. As an inhibitor of keratinocyte proliferation and inductor of keratinocyte apoptosis, transforming growth factor beta1 (TGF-beta1) has been proposed to play an important role in catagen regulation. This is suggested, for example, by maximal expression of TGF-beta1 and its receptors during late anagen and the onset of catagen of the hair cycle. We examined the potential involvement of TGF-beta1 in catagen control. We compared the first spontaneous entry of hair follicles into catagen between TGF-beta1 null mice and age-matched wild-type littermates, and assessed the effects of TGF-beta1 injection on murine anagen hair follicles in vivo. At day 18 p.p., hair follicles in TGF-beta1 -/- mice were still in early catagen, whereas hair follicles of +/+ littermates had already entered the subsequent resting phase (telogen). TGF-beta1-/- mice displayed more Ki-67-positive cells and fewer apoptotic cells than comparable catagen follicles from +/+ mice. In contrast, injection of TGF-beta1 into the back skin of mice induced premature catagen development. In addition, the number of proliferating follicle keratinocytes was reduced and the number of TUNEL + cells was increased in the TGF-beta1-treated mice compared to controls. Double visualization of TGF-beta type II receptor (TGFRII) and TUNEL reactivity revealed colocalization of apoptotic nuclei and TGFRII in catagen follicles. These data strongly support that TGF-beta1 ranks among the elusive endogenous regulators of catagen induction in vivo, possibly via the inhibition of keratinocyte proliferation and induction of apoptosis. Thus, TGF-betaRII agonists and antagonists may provide useful therapeutic tools for human hair growth disorders based on premature or retarded catagen development (effluvium, alopecia, hirsutism).

The possible role of p53 and bcl-2 expression in cervical carcinomas and their premalignant lesions

OBJECTIVE

The purpose of this study was to assess the expression and clinical significance of bcl-2 and p53 in the progression of cervical neoplasias.

METHODS

One hundred seventy-one cervical specimens, consisting of normal cervical epithelium (n = 13), lesions with histological features of HPV infection (n = 14), CIN (cervical intraepithelial neoplasia) lesions (n = 63), and cervical carcinomas (n = 81) were examined immunohistochemically in paraffin sections.

RESULTS

Twenty-three specimens showed p53 expression [3/20 (15%) CIN III, 18/63 (29%) ISCC (invasive squamous cervical carcinoma), and 2/18 (11%) adenocarcinomas] while 63 cases expressed the bcl-2 gene [10/13 (77%) normal, 0/14(0%) condylomas, 6/23 (26%) CIN I, 9/20 (45%) CIN II, 15/20 (75%) CIN III, 18/63 (29%) ISCC, and 5/18 (28%) adenocarcinomas]. The expression of bcl-2 was found to increase in direct relation to the grade of CIN (P = 0.02) whereas such a trend was not observed for p53. p53 was not detected in normal or premalignant lesions (except 3 out of 20 cases of CIN III). There was no significant correlation between the expression of p53 and the histological type of cervical carcinoma, even though expression of p53 was higher in ISCC than in adenocarcinomas (29% vs 11%, respectively). In cervical cancer patients, expression of bcl-2 was correlated to a greater than 5-year survival (P < 0.01) while no prognostic significance of p53 expression was found.

CONCLUSION

Evaluation of bcl-2 expression may provide additional and independent prognostic information for the clinical course of the disease and therefore to be developed as a prognostic indicator for cervical cancer.

Increased p27Kip1 Cyclin-Dependent Kinase Inhibitor Gene Expression Following Anti-IgM Treatment Promotes Apoptosis of WEHI 231 B Cells

Engagement of the B cell receptor of WEHI 231 immature B cells leads sequentially to a drop in c-Myc, to induction of the cyclin-dependent kinase inhibitor p27Kip1, and finally to apoptosis. Recently we demonstrated that the drop in c-Myc expression promotes cell death, whereas the induction of p27 has been shown to lead to growth arrest. In this paper, we demonstrate that increased p27 expression also promotes apoptosis of WEHI 231 B cells. The rescue of WEHI 231 cells by CD40 ligand engagement of its receptor prevented the increase in p27 induction. Inhibition of p27-ablated apoptosis induced upon expression of antisense c-myc RNA. Furthermore, specific induction of p27 gene expression resulted in apoptosis of WEHI 231 cells. Lastly, inhibition of expression of c-Myc, upon induction of an antisense c-myc RNA vector, was sufficient to induce increased p27 levels and apoptosis. Thus, these findings define a signaling pathway during B cell receptor engagement in which the drop in c-Myc levels leads to an increase in p27 levels that promotes apoptosis.

Structural alterations of transforming growth factor-beta receptor genes in human cervical carcinoma

The development and progression of invasive uterine cervical carcinomas appear to be associated with the progressive loss of sensitivity to transforming growth factor-beta (TGFbeta)-mediated cell cycle arrest. In order to identify possible molecular mechanisms responsible for TGFbeta resistance, we screened the 7 exons of the type II (TbetaR-II) TGFbeta receptor and the 9 exons of the type I (TbetaR-I) TGFbeta receptor genes for mutations in 16 paraffin-embedded primary invasive cervical carcinoma specimens. In one of these carcinomas, we found a novel G-->T transversion in exon 3 of TbetaR-II that introduces a premature stop codon (E142Stop) and presumably results in the synthesis of a truncated soluble exoreceptor. In one tumor, a silent A-->C transversion mutation that may affect mRNA splicing was present in exon 6 of TbetaR-I. In addition, 7 of 16 cases were heterozygous for a G-->A polymorphism in intron 7 of TbetaR-I. Finally, we identified a 9 base pair in-frame germline deletion in exon 1 of TbetaR-I resulting in loss of 3 of 9 sequential alanine residues at the N-terminus in 6 of 16 cases. Analysis of specimens from case-control studies indicated that carriers of this del(GGC)3 TbetaR-I variant allele may be at a increased risk for the development of cervical carcinoma (p=0.22). Furthermore, the response of cells expressing the variant receptor to TGFbeta was diminished. Our results support the notion that diverse alterations in the TGFbeta signaling pathway may play a role in the development of cervical cancer.