The prognostic significance of transforming growth factors in human breast cancer

Exploiting Canonical TGFβ Signaling in Cancer Treatment

Transforming growth factor β (TGFβ) is a pleiotropic cytokine that plays critical roles to define cancer cell phenotypes, construct the tumor microenvironment, and suppress anti-tumor immune responses. As such, TGFβ is a lynchpin for integrating cancer cell intrinsic pathways and communication among host cells in the tumor and beyond that together affect responses to genotoxic, targeted, and immune therapy. Despite decades of preclinical and clinical studies, evidence of clinical benefit from targeting TGFβ in cancer remains elusive. Here, we review the mechanisms by which TGFβ acts to oppose successful cancer therapy, the reported prognostic and predictive value of TGFβ biomarkers, and the potential impact of inhibiting TGFβ in precision oncology. Paradoxically, the diverse mechanisms by which TGFβ impedes therapeutic response are a principal barrier to implementing TGFβ inhibitors because it is unclear which TGFβ mechanism is functional in which patient. Companion diagnostic tools and specific biomarkers of TGFβ targeted biology will be the key to exploiting TGFβ biology for patient benefit.

Roles of adiponectin and leptin signaling-related microRNAs in the preventive effects of calorie restriction in mammary tumor development

Calorie restriction (CR) is suggested to prevent the development of mammary tumors (MTs); however, the mechanism remains to be clarified. We aimed to determine the microRNA (miRNA) profile in mice applied to 2 different CR protocols; chronic (CCR) and intermittent (ICR) and follow the MT development. In addition, the roles of miRNAs involved in adiponectin and/or leptin signaling pathways were investigated. Mice were divided into 3 groups: ad-libitum (AL), CCR, or ICR, which comprised 3 weeks of AL feeding followed by 1 week of 60% CR in a cyclic manner. Blood and tissue collection were performed at weeks 10, 17/18, 49/50 and 81/82. Long-term CCR provided better protection compared with ICR for MT development with a delay in the MT occurrence. Adiponectin expression in mammary fat pad were significantly higher in CCR group compared with AL. Using GeneChip Array, 250 of 3195 miRNAs were differentially expressed among the dietary groups. Thirteen of 250 miRNAs were related to adiponectin and/or leptin signaling genes. Results were verified by reverse transcription polymerase chain reaction. Specifically, miR-326-3p, miR-500-3p and miR-129-5p, which are related to adiponectin and/or leptin signaling, may play important roles in the preventive effects of CR in MT development and in ageing. Thus, these miRNAs might be putative biomarkers to target for diagnostic and treatment purposes. Novelty: Type of CR and micro RNA interaction is related to ageing. miR-326-3p, miR-500-3p and miR-129-5p expression levels were differentially expressed in MT development and in ageing. The genes associated with adiponectin and/or leptin signaling pathways are regulated by certain miRNAs in the protective effects of CR.

MicroRNA-374b inhibits breast cancer progression through regulating CCND1 and TGFA genes

Emerging evidence indicates that microRNAs (miRNAs) play a critical role in breast cancer development. We recently reported that a higher expression of miR-374b in tumor tissues was associated with a better disease-free survival of triple-negative breast cancer (TNBC). However, the functional significance and molecular mechanisms underlying the role of miR-374b in breast cancer are largely unknown. In this current study, we evaluated the biological functions and potential mechanisms of miR-374b in both TNBC and non-TNBC. We found that miR-374b was significantly downregulated in breast cancer tissues, compared to adjacent tissues. MiR-374b levels were also lower in breast cancer cell lines, as compared to breast epithelial cells. In vitro and in vivo studies demonstrated that miR-374b modulates the malignant behavior of breast cancer cells, such as cell proliferation in 2D and 3D, cell invasion ability, colony-forming ability and tumor growth in mice. By using bioinformatics tools, we predicted that miR-374b plays a role in breast cancer cells through negatively regulating cyclin D1 (CCND1) and transforming growth factor alpha (TGFA). We further confirmed that CCND1 and TGFA contribute to the malignant behavior of breast cancer cells in vitro and in vivo. Our rescue experiments showed that overexpressing CCND1 or TGFA reverses the phenotypes caused by miR-374b overexpression. Taken together, our studies suggest that miR-374b modulates malignant behavior of breast cancer cells by negatively regulating CCND1 and TGFA genes. The newly identified miR-374b-mediated CCND1 and TGFA gene silencing may facilitate a better understanding of the molecular mechanisms of breast cancer progression.

TGF-β1 mediates the effects of aspirin on colonic tumor cell proliferation and apoptosis

Previous studies have demonstrated that aspirin serves an important role in chemoprevention and the suppression of colorectal cancer (CRC); however, the underlying mechanisms for this inhibition by aspirin remain unclear. Aspirin is capable of promoting apoptosis through prostaglandin-dependent orprostaglandin-independent signaling pathways. In the prostaglandin-dependent pathways, inhibition of cyclooxygenase (COX), particularly COX-2, is the primary mechanism known to be involved in aspirin-induced CRC suppression. Previous studies have implicated prostaglandin-independent signaling pathways and certain associated proteins, including SOX7, in aspirin-induced CRC suppression. In the present study, a newly-characterized association between aspirin, transforming growth factor (TGF)-β1 and CRC inhibition was identified. Specifically, aspirin triggers CRC cell apoptosis by inducing the secretion of TGF-β1, and the increased TGF-β1 then leads to apoptosis and proliferation inhibition in CRC cells.

Transcriptome Analysis of the Thymus in Short-Term Calorie-Restricted Mice Using RNA-seq

Calorie restriction (CR), which is a factor that expands lifespan and an important player in immune response, is an effective protective method against cancer development. Thymus, which plays a critical role in the development of the immune system, reacts to nutrition deficiency quickly. RNA-seq-based transcriptome sequencing was performed to thymus tissues of MMTV-TGF-α mice subjected to ad libitum (AL), chronic calorie restriction (CCR), and intermittent calorie restriction (ICR) diets in this study. Three cDNA libraries were sequenced using Illumina HiSeq™ 4000 to produce 100 base pair-end reads. On average, 105 million clean reads were mapped and in total 6091 significantly differentially expressed genes (DEGs) were identified (p < 0.05). These DEGs were clustered into Gene Ontology (GO) categories. The expression pattern revealed by RNA-seq was validated by quantitative real-time PCR (qPCR) analysis of four important genes, which are leptin, ghrelin, Igf1, and adinopectin. RNA-seq data has been deposited in NCBI Gene Expression Omnibus (GEO) database (GSE95371). We report the use of RNA sequencing to find DEGs that are affected by different feeding regimes in the thymus.

Eicosanoids and adipokines in breast cancer: from molecular mechanisms to clinical considerations

Chronic inflammation is one of the foremost risk factors for different types of malignancies, including breast cancer. Additional risk factors of this pathology in postmenopausal women are weight gain, obesity, estrogen secretion, and an imbalance in the production of adipokines, such as leptin and adiponectin. Various signaling products of transcription factor, nuclear factor-kappaB, in particular inflammatory eicosanoids, reactive oxygen species (ROS), and cytokines, are thought to be involved in chronic inflammation-induced cancer. Together, these key components have an influence on inflammatory reactions in malignant tissue damage when their levels are deregulated endogenously. Prostaglandins (PGs) are well recognized in inflammation and cancer, and they are solely biosynthesized through cyclooxygenases (COXs) from arachidonic acid. Concurrently, ROS give rise to bioactive isoprostanes from arachidonic acid precursors that are also involved in acute and chronic inflammation, but their specific characteristics in breast cancer are less demonstrated. Higher aromatase activity, a cytochrome P-450 enzyme, is intimately connected to tumor growth in the breast through estrogen synthesis, and is interrelated to COXs that catalyze the formation of both inflammatory and anti-inflammatory PGs such as PGE(2), PGF(2α), PGD(2), and PGJ(2) synchronously under the influence of specific mediators and downstream enzymes. Some of the latter compounds upsurge the intracellular cyclic adenosine monophosphate concentration and appear to be associated with estrogen synthesis. This review discusses the role of COX- and ROS-catalyzed eicosanoids and adipokines in breast cancer, and therefore ranges from their molecular mechanisms to clinical aspects to understand the impact of inflammation.

TGF-β polymorphism and its expression correlated with CXCR4 expression in human breast cancer

The role of chemokines and the growth factors has been extensively analyzed both in cancer risk and tumor progression. The transforming growth factor beta (TGF-β) and chemokine (C-X-C motif) receptor 4 (CXCR4) genes are implicated in several diseases, including breast cancer. Genomic DNA was obtained from 21 samples of peripheral blood or from normal tissue, previously fixed in formalin and embedded in paraffin for TGF-β T869C polymorphism analyses. Total cellular RNA was extracted from the same 21 patients, but from fresh tissue (tumor and adjacent healthy from the same breast) for expression analysis by Real Time PCR. No significant differences were observed in genotype distribution according to clinicopathological characteristics. Transforming growth factor beta (TGF-β) mRNA expression was assessed according to T869C polymorphism and CC patients presented a higher TGF-β expression but not significant when compared to other genotypes (p = 0.064). A positive correlation was observed in relative mRNA expressions of CXCR4 and TGF-β (p = 0.020). It is known that overexpression of TGF-β by both tumor and stromal tissue can facilitate the development of metastases, mainly by TGF-β stimulated angiogenesis and increased tumor cell motility. Our findings suggested a role of these genes as progression markers for breast carcinoma.

Effects of chronic vs. intermittent calorie restriction on mammary tumor incidence and serum adiponectin and leptin levels in MMTV-TGF-α mice at different ages

Calorie restriction prevents mammary tumor (MT) development in rodents. Usually, chronic calorie restriction (CCR) has been implemented. In contrast, intermittent calorie restriction (ICR) has been less frequently used. Recent studies indicate that when a direct comparison of the same degree of CCR vs. ICR was made using MMTV-TGF-α mice which develop MTs in the second year of life, ICR provided greater protection than CCR in delaying MT detection and reducing tumor incidence. Adiponectin and leptin are two adipocytokines secreted from adipose tissue which have opposite effects on many physiological functions, including proliferation of human breast cancer cells. A recent study indicated that a low adiponectin/leptin ratio was associated with breast cancer. We evaluated the relationship of adiponectin and leptin to MT development in MMTV-TGF-α calorie-restricted mice at several ages. Mice were enrolled at 10 weeks of age and subjected to 25% caloric reduction implemented either chronically or intermittently. Mice were euthanized at designated time points up to 74 weeks of age. Serum samples were collected to measure adiponectin and leptin concentrations. Both CCR and ICR mice had significantly reduced MT incidence. For the groups studied, serum leptin increased over time, while there was a trend for an increase in serum adiponectin levels in ad libitum and ICR mice, with no change in CCR mice between 10 and 74 weeks of age. The adiponectin/leptin ratio was significantly reduced as mice aged, but this ratio in ICR mice was significantly higher than that for ad libitum and CCR mice. No correlation was noted between serum adiponectin and leptin. These findings demonstrate that intermittent calorie restriction delays the early development of MTs. This delay was associated with reduced serum leptin levels following the restriction phases of the protocol. Additionally, serum leptin levels correlated with body weight and body fat in the groups studied.

Immuno-modulatory gene polymorphisms and outcome in breast and ovarian cancer

Breast and ovarian cancer continue to be a significant source of morbidity and mortality. Improved understanding of signalling pathways related to growth and apoptosis has led to targeted treatments and modest improvement in long term outcomes. However, it has become increasingly clear that tumor factors alone are not the sole determinants of outcome in patients with breast and ovarian cancer. The tumor microenvironment and other immunologic host processes play an integral role in the overall interactions between disease, host and treatment. Cytokines play a major role in the immune response to tumors. Single nucleotide polymorphisms (SNPs) in the regulatory or coding regions of many cytokine genes lead to functional alterations in the transcriptional regulation of these genes or the proteins they encode. This review examines the current literature linking functional variants in cytokine and other immune genes to outcomes in breast and ovarian cancer. We have focused on those involved in the proinflammatory response (IL-6, TNF-alpha), apoptosis (TGF-beta, Fas, FasL, C1QA), angiogenesis (IL-8) and autoimmunity (IL-10). While much remains to be learned about the mechanisms underlying these variants and their impact on tumor behavior, this area holds promise for future development of prognostic profiles and therapeutics exploiting the immune response.

TGF-beta1 genotype and phenotype in breast cancer and their associations with IGFs and patient survival

Transforming growth factor-beta (TGF-beta)-mediated signals play complicated roles in the development and progression of breast tumour. The purposes of this study were to analyse the genotype of TGF-beta1 at T29C and TGF-beta1 phenotype in breast tumours, and to evaluate their associations with IGFs and clinical characteristics of breast cancer. Fresh tumour samples were collected from 348 breast cancer patients. TGF-beta1 genotype and phenotype were analysed with TaqMan and ELISA, respectively. Members of the IGF family in tumour tissue were measured with ELISA. Cox proportional hazards regression analysis was performed to assess the association of TGF-beta1 and disease outcomes. Patients with the T/T (29%) genotype at T29C had the highest TGF-beta1, 707.9 pg mg(-1), followed by the T/C (49%), 657.8 pg mg(-1), and C/C (22%) genotypes, 640.8 pg mg(-1), (P=0.210, T/T vs C/C and C/T). TGF-beta1 concentrations were positively correlated with levels of oestrogen receptor, IGF-I, IGF-II and IGFBP-3. Survival analysis showed TGF-beta1 associated with disease progression, but the association differed by disease stage. For early-stage disease, patients with the T/T genotype or high TGF-beta1 had shorter overall survival compared to those without T/T or with low TGF-beta1; the hazard ratios (HR) were 3.54 (95% CI: 1.21-10.40) for genotype and 2.54 (95% CI: 1.10-5.89) for phenotype after adjusting for age, grade, histotype and receptor status. For late-stage disease, however, the association was different. The T/T genotype was associated with lower risk of disease recurrence (HR=0.13, 95% CI: 0.02-1.00), whereas no association was found between TGF-beta1 phenotype and survival outcomes. The study suggests a complex role of TGF-beta1 in breast cancer progression, which supports the finding of in vitro studies that TGF-beta1 has conflicting effects on tumour growth and metastasis.

Expression of reversion-inducing-cysteine-rich protein with Kazal motifs, matrix metalloproteinase-9 and transforming growth factor-β1 and their correlations in gastric carcinomas

AIM: To study the expression of RECK (reversion-inducing-cysteine-rich protein with Kazal motifs), MMP-9 (matrix metalloproteinase-9), and TGF-β1 (transforming growth factor-β1) as well as their correlations in gastric cancer, and to investigate their roles in the carcinogenesis and and development.

METHODS: PV-9000 immunohistochemistry was used to measure the expression of RECK, MMP-9, and TGF-β1 in 54 samples of gastric carcinoma selected from paraffin wax-embodied specimens with complete clinicopathological data, and another 15 cases of normal gastric mucosa.

RESULTS: The expression rate of RECK in gastric cancer was low (51.9%), and reduced with the increased invasive depth and clinical stages, decreased histological differentiation and occurrence of lymphatic and long-distance metastasis (P < 0.05). The expression rate of MMP-9 in gastric cancer was high (75.9%), and elevated with the increased invasive depth and clinical stages, decreased histological differentiation, and occurrence of lymphatic metastasis (P < 0.05). The expression rate of TGF-β1 in gastric cancer was also high (77.8%), and enhanced with the increased clinical stages, reduced histological differentiation and occurrence of lymphatic metastasis (P < 0.05). The expression of RECK was negatively correlated with the expression of MMP-9 and TGF-β1 (r = -0.618, P < 0.001; r = -0.620, P < 0.001), while the expression of MMP-9 was positively correlated with that of TGF-β1 (r = 0.716, P < 0.001).

CONCLUSION: RECK is lowly expressed in gastric caner, but MMP-9 and TGF-β1 are highly expressed. RECK, MMP-9 and TGF-β1 may serve as the markers in the estimation of metastasis and dissemination of gatric cnacer.

Determination of TGFbeta1 protein level in human primary breast cancers and its relationship with survival

Transforming growth factor-beta (TGFbeta)1 is thought to be implicated in breast cancer progression. However, data about the influence of TGFbeta1 on breast cancer development are conflicting. To clarify the clinical relevance of TGFbeta1, TGFbeta1 protein level has been measured by enzyme-immunoassay in 193 breast tumour samples. We found that 94.3% of patients expressed TGFbeta1 with a range of 0-684 pg mg(-1) protein. In the overall population, an increase of tumoral TGFbeta1 was observed in premenopausal patients when compared to postmenopausal subgroup (P=0.0006). When patients were subdivided according to nodal status, TGFbeta1 was correlated to type-1 plasminogen activator inhibitor in the node-negative subgroup (P=0.040). Multivariate analysis revealed that, after lymph node status (P=0.0002) and urokinase-type plasminogen activator (P=0.004), TGFbeta1 was an independent prognostic marker for DFS (P=0.005) in the overall population. In the node-negative population, TGFbeta1 was the prominent prognostic factor (P=0.010). In the same population, Kaplan-Meier curves demonstrated that high TGFbeta1 level was correlated with a shorter disease-free survival (P=0.020). These data suggest that the measurement of tumoral TGFbeta1 protein level, especially for node-negative patients, might help to identify a high-risk population early in tumour progression.

TGFbeta1/Smad3 counteracts BRCA1-dependent repair of DNA damage

Inactivation of the BRCA1 gene has been found to confer susceptibility to early-onset familial breast and ovarian cancers. BRCA1 regulates DNA repair, chromatin remodeling and affects gene transcription. Transforming growth factor-beta (TGFbeta) is a potent regulator of growth, apoptosis and invasiveness of tumor cells, including breast cancer cells. Here we show that Smad3 which is a component of the TGFbeta signaling pathway, forms a complex with BRCA1 in vitro and in vivo. The interaction is mediated by the MH1 domain of Smad3 and the C-terminal part of BRCA1. We observed a co-localization of Smad3 and BRCA1 in nuclear complexes. We also found that TGFbeta1/Smad3 counteracted BRCA1-dependent repair of DNA double-strand breaks in human breast epithelial cells, as evaluated by BRCA1 nuclear foci formation, single-cell gel electrophoresis and cell survival assays. Thus, TGFbeta1/Smad3 suppresses BRCA1-dependent DNA repair in response to a DNA damaging agent.

Role of transforming growth factor β in breast carcinogenesis

Transforming growth factor (TGF) beta is a pre-eminent negative growth regulator that has antiproliferative effects on a range of epithelial cells. This ability has evoked interest in this growth factor as a tumour suppressor with potential clinical significance. In the early stages of breast carcinogenesis, a growth-inhibitory response to TGFbeta is maintained, which depends on an intact TGFbeta signalling pathway. Tumour development and progression of cells along a neoplastic continuum is accompanied by loss of this growth-inhibitory response to TGFbeta, which might instead promote tumour growth indirectly through a combination of permissive effects on stromal tissue, angiogenesis, and the immune system. This review discusses the complexity of functional pleiotropy and the continually changing roles of TGFbeta as a tumour evolves, along with competing therapeutic strategies. The boosting of local endogenous amounts of TGFbeta in conjunction with enhancement of cellular responsiveness might be appropriate in early malignant disease, and anti-TGFbeta approaches could yield a therapeutic gain in metastatic states.

Transforming growth factor B1 T29C polymorphism and breast cancer risk in Japanese women

BACKGROUND

A cohort study for Caucasians aged 65 years or older demonstrated a marked breast cancer risk reduction for those with the CC genotype of transforming growth factor B1 (TGF B1) T29C polymorphism. This is a prevalent case-control study to examine the reported risk reduction for Japanese women.

PATIENTS AND METHODS

A total of 232 histologically diagnosed breast cancer patients who visited Aichi Cancer Center Hospital between June 1999 and March 2000 were enrolled. The controls were 172 female outpatients without cancer at the same hospital. DNA was extracted from peripheral blood, and TGF B1 genotype was determined by PCR-CTPP.

RESULTS

The genotype frequency was 23.7% for TT, 49.2% for TC, and 27.1% for CC among controls, and 28.9%, 46.1%, and 25.0%, respectively, among cases. Age-adjusted odds ratio (OR) relative to the TT genotype was 0.81 (95% confidence interval, 0.50-1.31) for the TC genotype and 0.77 (0.45-1.34) for the CC genotype. For premenopausal women, the CC genotype was significantly associated with reduced risk of breast cancer in comparison with the TT genotype (OR=0.45, 0.20-0.98). The association was not observed for postmenopausal women (OR=1.40, 0.64-3.08).

CONCLUSION

The present study showed risk reduction for Japanese premenopausal women with the CC genotype, but not for postmenopausal Japanese women.

Expression of bone morphogenetic proteins in acute promyelocytic leukemia before and after combined all trans-retinoic acid and cytotoxic treatment

We investigated the dynamics of bone morphogenetic protein (BMP) and their receptor mRNA expression in relation to combined treatment with all trans-retinoic acid (ATRA) and chemotherapy in four patients with acute promyelocytic leukemia (APL). Reverse transcription-polymerase chain reaction (RT-PCR) analysis of the bone marrow cells at diagnosis showed strong expression of BMP-2, -4, and -7, and their receptors RIA, RIB, and RII, parallel to the expression of promyelocytic leukemia/retinoic acid receptor alpha (PML/RARalpha) fusion gene transcripts. Therapeutic clearance of the tumor molecular marker corresponded to the absence of BMP expression, suggesting the possible role of BMPs as markers of the minimal residual disease (MRD) in APL.

Inhibiting the TGF-beta signalling pathway as a means of cancer immunotherapy

Cancers have developed numerous mechanisms for escaping the immune response, either by successfully evading a fully functional immune system or by actively suppressing the immune system so that they are no longer recognised or effectively eliminated. Current evidence supports active cancer cell-mediated immunosuppression via the secretion of the potent immunosuppressive cytokine, transforming growth factor-beta (TGF-beta), as the most general and potent mechanism for human cancer cells to escape the immune system. Efforts to bypass TGF-beta-mediated immunosuppression thereby represent an attractive therapeutic strategy for the chemoprevention and treatment of human cancers, both by directly increasing the efficacy of immunosurveillance and by increasing the efficacy of current immunotherapy strategies. Current approaches are limited by their nonspecific effects on the TGF-beta signalling pathway, as TGF-beta pathways which specifically mediate immunosuppression have not yet been defined. Future efforts should be directed towards elucidating specific TGF-beta pathways so that these can be targeted for the chemoprevention and treatment of human cancers.

Renal mRNA levels as prognostic tools in kidney diseases

Molecular biologic techniques are currently considered as new diagnostic and prognostic parameters with a sensitivity and specificity exceeding those of histologic and functional data currently used in clinical practice. The results in various clinical settings have been of limited value up to now. This study is an investigation of the use of tissue levels of RNA determined in routine clinical kidney biopsies as prognostic tools. The focus was on RNA encoding for molecules known to be involved in the pathogenesis of renal disorders. Fresh kidney biopsy tissue was obtained from 52 patients with various renal diseases. The GFR was followed for 12 mo. The extent of glomerulosclerosis and interstitial fibrosis in the biopsies was determined with quantitative digital image analysis. Glomerular and tubulointerstitial compartments from each biopsy specimen were separated, and mRNA levels of TGF-beta, collagen I, collagen IV, and fibronectin were quantitated by real-time PCR. Correlations, along with 95% confidence intervals (CI), between all variables tested at time biopsy were determined. To assess their prognostic value, these variables were correlated with the slope of GFR within several time intervals after biopsy. In addition, to evaluate the predictive value of the variables for outcome in individual patients, differences for each variable were tested between patients showing progressive decline in renal function (slope GFR < 0) and patients showing stable or improving renal function over time (slope GFR >or= 0). In chronic renal diseases, the extent of histologic damage correlated with the GFR at the time of biopsy (r = -0.44; CI -0.68 to -0.11), but it did not correlate with the slope expressing a change in GFR after the biopsy. Tubulointerstitial TGF-beta mRNA levels correlated with the rate of change in GFR between time of biopsy and 1 mo later (r = 0.41; CI, 0.07 to 0.67). The GFR at the time of biopsy correlated with the slope of change in GFR between time of biopsy and 12 mo later (r = -0.50; CI, -0.73 to -0.18). In chronic renal diseases, glomerular fibronectin mRNA levels, in comparison with the GFR at time of biopsy, correlated relatively strongly with the slope of change in GFR between 3 and 12 mo (r = 0.50; CI, 0.16 to 0.74). Patients with favorable renal outcome after 12 mo showed significantly higher TGF-beta mRNA levels and lower proteinuria levels at time of biopsy (P < 0.05) than patients with a progressive decline in renal function. This study shows that mRNA levels measured in kidney biopsies can function as prognostic tools in human renal diseases. In particular, relatively high levels of tubulointerstitial TGF-beta mRNA and glomerular fibronectin mRNA are associated with less deterioration in renal function.

The EGF receptor family--multiple roles in proliferation, differentiation, and neoplasia with an emphasis on HER4

The EGF Receptor (EGFR), the first transmembrane receptor tyrosine kinase cloned and sequenced, and its closely related family members HER2, HER3, and HER4, play myriad roles in mammalian growth and development. Receptor activation involves ligand binding to separate receptors followed by formation of active dimers. These receptors can signal as homodimers or they can subtly alter signaling output by heterodimerizing with other family members. Adding complexity, these receptors with varying specificity bind at least 10 ligands from two ligand families, the EGF and neuregulin/heregulin families. This signaling system's impact on human neoplasia is underscored by the following: i.) EGFR is overexpressed or activated by autocrine or paracrine growth factor loops in at least 50% of epithelial malignancies; ii.) HER2 is amplified and dramatically overexpressed in approximately 20%-25% or breast cancers; iii) HER3 and HER4 are variably expressed in breast and other cancers. Overexpression and/or activation of EGFR, HER2 and HER3 has been correlated with poor tumor prognosis; antibody and small molecule inhibitors of their activity are being tested as therapy in cancer patients. However, the signaling complexity engendered by four interacting receptors and ten ligands makes it difficult to definitively measure receptor signaling output in human tumors and even makes mechanistic studies of the family's role in normal physiology and neoplastic transformation a challenge. In spite of the literature's emphasis on growth control, activation by some EGF receptor family member ligands can produce tumor cell differentiation, characterized by growth cessation and differentiation gene product synthesis. The present work delineates a role for HER4 in breast cancer cell differentiation and demonstrates that HER4 is both necessary and sufficient to produce an anti-proliferative signal. These

Suppressor and oncogenic roles of transforming growth factor-beta and its signaling pathways in tumorigenesis

Transforming growth factor-beta (TGF-beta) has been implicated in oncogenesis since the time of its discovery almost 20 years ago. The complex, multifunctional activities of TGF-beta endow it with both tumor suppressor and tumor promoting activities, depending on the stage of carcinogenesis and the responsivity of the tumor cell. Dysregulation or alteration of TGF-beta signaling in tumorigenesis can occur at many different levels, including activation of the ligand, mutation or transcriptional suppression of the receptors, or alteration of downstream signal transduction pathways resulting from mutation or changes in expression patterns of signaling intermediates or from changes in expression of other proteins which modulate signaling. New insights into signaling from the TGF-beta receptors, including the identification of Smad signaling pathways and their interaction with mitogen-activated protein (MAP) kinase pathways, are providing an understanding of the changes involved in the change from tumor suppressor to tumor promoting activities of TGF-beta. It is now appreciated that loss of sensitivity to inhibition of growth by TGF-beta by most tumor cells is not synonymous with complete loss of TGF-beta signaling but rather suggests that tumor cells gain advantage by selective inactivation of the tumor suppressor activities of TGF-beta with retention of its tumor promoting activities, especially those dependent on cross talk with MAP kinase pathways and AP-1.

Mechanisms of action of flavopiridol

Flavopiridol inhibits phosphokinases. Its activity is strongest on cyclin dependent kinases (cdk-1, -2, -4, -6, -7) and less on receptor tyrosine kinases (EGFR), receptor associates tyrosine kinases (pp60 Src) and on signal transducing kinases (PKC and Erk-1). Although the inhibiting activity of flavopiridol is strongest for cdk, the cytotoxic activity of flavopiridol is not limited to cycling cells. Resting cells are also killed. This fact suggests that inhibition of cdks involved in the control of cell cycle is not the only mechanism of action. Inhibition of cdk's with additional functions (i.e. involved in the control of transcription or function of proteins that do not control cell cycle) may contribute to the antitumoral effect. Moreover, direct and indirect inhibition of receptor activation (EGFR) and/or a direct inhibition of kinases (pp60 Src, PKC, Erk-1) involved in the signal transduction pathway could play a role in the antiproliferative activity of flavopiridol. From pharmacokinetic data in patients it can be concluded that the inhibitory activity (IC50) of flavopiridol on these kinases is in the range of concentrations that might be achieved intracellularly after systemic application of non-toxic doses of flavopiridol. However, no in situ data from flavopiridol treated cells have been published yet that prove that by inhibition of EGFR, pp60 Src, PKC and/or Erk-1 (in addition to inhibition of cdk's) flavopiridol is able to induce apoptosis. Thus many questions regarding the detailed mechanism of antitumoral action of flavopiridol are still open. For the design of protocols for future clinical studies this review covers the essential information available on the mechanism of antitumoral activity of flavopiridol. The characteristics of this antitumoral activity include: High rate of apoptosis, especially in leukemic cells; synergy with the antitumoral activity of many cytostatics; independence of its efficacy on pRb, p53 and Bcl-2 expression; lack of interference with the most frequent multidrug resistance proteins (P-glycoprotein and MRP-190); and a strong antiangiogenic activity. Based on these pharmacological data it can be concluded that flavopiridol could be therapeutically active in tumor patients: independent on the genetic status of their tumors or leukemias (i.e. mutations of the pRb and/or p53, amplification of bcl-2); in spite of drug resistance of their tumors induced by first line treatment (and caused by enhanced expression of multidrug resistance proteins); in combination with conventional chemotherapeutics preferentially given prior to flavopiridol; and due to a complex mechanism involving cytotoxicity on cycling and on resting tumor cells, apoptosis and antiangiogenic activity. In consequence, flavopiridol is a highly attractive, new antitumoral compound and deserves further elucidation of its clinical potency.

Role of transforming growth factor beta in cancer

Transforming growth factor beta (TGF-beta) is an effective and ubiquitous mediator of cell growth. The significance of this cytokine in cancer susceptibility, cancer development and progression has become apparent over the past few years. TGF-beta plays various roles in the process of malignant progression. It is a potent inhibitor of normal stromal, hematopoietic, and epithelial cell growth. However, at some point during cancer development the majority of transformed cells become either partly or completely resistant to TGF-beta growth inhibition. There is growing evidence that in the later stages of cancer development TGF-beta is actively secreted by tumor cells and not merely acts as a bystander but rather contributes to cell growth, invasion, and metastasis and decreases host-tumor immune responses. Subtle alteration of TGF-beta signaling may also contribute to the development of cancer. These various effects are tissue and tumor dependent. Identifying and understanding TGF-beta signaling pathway abnormalities in various malignancies is a promising avenue of study that may yield new modalities to both prevent and treat cancer. The nature, prevalence, and significance of TGF-beta signaling pathway alterations in various forms of human cancer as well as potential preventive and therapeutic interventions are discussed in this review.

Role of transforming growth factor beta in cancer

Transforming growth factor beta (TGF-beta) is an effective and ubiquitous mediator of cell growth. The significance of this cytokine in cancer susceptibility, cancer development and progression has become apparent over the past few years. TGF-beta plays various roles in the process of malignant progression. It is a potent inhibitor of normal stromal, hematopoietic, and epithelial cell growth. However, at some point during cancer development the majority of transformed cells become either partly or completely resistant to TGF-beta growth inhibition. There is growing evidence that in the later stages of cancer development TGF-beta is actively secreted by tumor cells and not merely acts as a bystander but rather contributes to cell growth, invasion, and metastasis and decreases host-tumor immune responses. Subtle alteration of TGF-beta signaling may also contribute to the development of cancer. These various effects are tissue and tumor dependent. Identifying and understanding TGF-beta signaling pathway abnormalities in various malignancies is a promising avenue of study that may yield new modalities to both prevent and treat cancer. The nature, prevalence, and significance of TGF-beta signaling pathway alterations in various forms of human cancer as well as potential preventive and therapeutic interventions are discussed in this review.

Tumour necrosis factor-alpha and transforming growth factor-beta are significantly associated with better prognosis in non-small cell lung carcinoma: putative relation with BCL-2-mediated neovascularization

Recent in vivo and in vitro studies have demonstrated a wide spectrum of biologic activities of cytokines in the pathogenesis and progression of malignancy. Tumour necrosis factor alpha (TNF-alpha) and transforming growth factor beta (TGF-beta) have emerged as two of the many host-derived mediators that seem to interfere with both antiproliferative and tumorigenic effects in malignant tumours including lung cancer. However, their association with tumour prognosis or prognostic factors has not yet been completely clarified. In this study, we assessed TNF-alpha and TGF-beta mRNA expression by RT-PCR technique in 61 NSCLC samples, demonstrating the presence of TNF-alpha and TGF-beta mRNA in 55.74% and 45.9% of cases, respectively. We also evaluated the expression of the two distinct transmembrane TNF receptors. TNFR-I and TNFR-II, with a PCR-positive signal in 70.49% and 65.57% of cases, respectively. In 49 of the 61 cases, we evaluated the prognostic impact of the two growth-inhibiting factors using the Kaplan-Meier analysis. In the univariate analysis patients without nodal metastatic involvement (P = 0.02), less advanced tumour stage (P = 0.02) or TNF-alpha and TGF-beta positive cancers (P = 0.01 and P = 0.03) showed a favourable prognosis in terms of overall survival. Since our previous studies demonstrated a significant association between NSCLC behaviour, neoangiogenesis and bcl-2 expression, we investigated the putative relation between TNF-alpha and TGF-beta on the one hand, and vascular count (as a measure of tumour angiogenesis) and bcl-2 protein expression, on the other hand. Our results showed a significant direct association between TNF-alpha and bcl-2 (P = 0.05) and an inverse association between TNF-alpha and microvessel count (P = 0.03). Moreover, as previously demonstrated, we observed a significant inverse correlation between bcl-2 protein expression and vascular count (P = 0.05), suggesting that the favourable effect of TNF-alpha on clinical outcome may be related to a bcl-2-mediated low neovascular development.

Use of specimen mammography-guided FNA (fine-needle aspirates) for flow cytometric multiple marker analysis and immunophenotyping in breast cancer

A pilot study of a novel translational research method to simultaneously assay multiple molecular markers and DNA in fine-needle aspirates (FNA) of mammographically detected breast lesions is described. Specimen mammography-guided 20-gauge FNAs obtained from 86 lesions and 22 areas of normal tissue were analyzed by multiparameter flow cytometry for DNA content, her2/neu, transforming growth factor alpha (TGF alpha), and the epithelial marker cytokeratin (CK) simultaneously. Epithelial cell her2/neu positivity was detected in 12 of 44 (27%) of invasive ductal carcinomas and 3 of 9 (33%) ductal carcinoma in situ (DCIS), 10 of 30 (33%) benign lesions, and 4 of 22 (18%) normal tissue aspirates. All lesions and normal tissue showed a similar positive rate for TGFalpha ranging from 61 to 76%. The CK(+)TGF alpha(-)her2/neu(+) immunophenotype was more frequently positive in aneuploid tumors (22%) than all other lesions (7%) (P < 0.05). Specimen mammography-guided FNAs provide fresh cells for flow cytometric multiple marker analysis and immunophenotyping of clinically occult breast lesions and normal tissue.

Kinase inhibitors in cancer therapy: a look ahead

The most essential kinases involved in cell membrane receptor activation, signal transduction and cell cycle control or programmed cell death and their interconnections are reviewed. In tumours, the genes of many of those kinases are mutated or amplified or the proteins are overexpressed. The use of key kinases offers the possibility to screen in vitro for synthetic small molecule kinase inhibitors. In view of the many interconnections of cellular kinases, their role in preventing or inducing programmed cell death and the possibility that a considerable number of signal transducing proteins are still unknown, cellular test systems are recommended in which the respective key kinase or one of its main partner molecules are overexpressed.

Loss of expression of transforming growth factor beta type II receptor correlates with high tumour grade in human breast in-situ and invasive carcinomas

AIMS

Loss of transforming growth factor beta type II receptor (TGFbeta-RII) expression has been associated with resistance to TGFbeta-mediated inhibition of cell proliferation and tumour progression. We investigated whether the expression of TGFbeta-RII is related to the progression of human breast cancer and whether there is a correlation between TGFbeta-RII expression and phenotypic markers of biological aggressiveness.

METHODS AND RESULTS

Immunohistochemical methods were used to detect TGFbeta-RII in archival breast samples including benign proliferative lesions, ductal carcinoma in situ (DCIS) and invasive mammary carcinomas (IMC). Neoplastic cells showed reduced expression of TGFbeta-RII in comparison to the normal breast tissue and benign lesions. There was a significant inverse correlation between loss of TGFbeta-RII expression and tumour grade within both DCIS (P = 0.004) and IMC (P = 0.001) groups. There was an inverse correlation between TGFbeta-RII expression and both mitotic count (P = 0.001) and clinical stage (P = 0.004). Oestrogen receptor (P = 0.07) and lymph node status (P = 0.10) were not significantly associated with TGFbeta-RII expression.

CONCLUSIONS

These data indicate that decreased expression of TGFbeta-RII may contribute to breast cancer progression and is related to a more aggressive phenotype in both in-situ and invasive carcinomas.

TGF-beta and cancer

The relationships between transforming growth factor-beta (TGF-beta) and cancer are varied and complex. The paradigm that is emerging from the experimental evidence accumulated over the past decade or so is that TGF-beta can play two different and opposite roles with respect to the process of malignant progression. During early stages of carcinogenesis, TGF-beta acts predominantly as a potent tumor suppressor and may mediate the actions of chemopreventive agents such as retinoids and nonsteroidal anti-estrogens. However, at some point during the development and progression of malignant neoplasms, bioactive TGF-betas make their appearance in the tumor microenvironment and the tumor cells escape from TGF-beta-dependent growth arrest. In many cases, this resistance to TGF-beta is the consequence of loss or mutational inactivation of the genes that encode signaling intermediates. These include the types I and II TGF-beta receptors, as well as receptor-associated and common-mediator Smads. The stage of tumor development or progression at which TGF-beta-resistant clones come to dominate the tumor cell population in different types of neoplasm remains to be defined. The phenotypic switch from TGF-beta-sensitivity to TGF-beta-resistance that occurs during carcinogenesis has several important implications for cancer prevention and treatment.

A role for intracellular immunization in chemosensitization of tumor cells?

Acquired drug resistance represents a major cause of chemotherapy failure in patients with cancer. The characterization of the molecular pathways involved in drug resistance has provided us with new targets to overcome this problem. Many of these target proteins are often overexpressed in human cancers. A number of gene therapy strategies, including antisense oligonucleotides, ribozymes and single-chain antibodies, have been developed to achieve the selective modulation and inhibition of various cellu- lar proteins. Thus, these approaches can be exploited to modulate the resistance phenotype of tumor cells. These gene therapy strategies represent a novel and unique way to enhance the sensitivity of tumor cells to chemotherapeutic drugs. This review will focus on the use of intracellular immunization as a means to modulate the expression of specific genetic determinants involved in the drug resistance phenotype.

Elevated serum levels of transforming growth factor-beta1 in patients with colorectal carcinoma: its association with tumor progression and its significant decrease after curative surgical resection

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) acts as a potent inhibitor of cell growth and tumor progression but loss of this negative regulation can contribute to tumor development. Some studies have reported an association between disease progression and TGF-beta1 expression in patients with colorectal carcinoma, but their results were not always consistent.

METHODS

Serum levels of TGF-beta1 were measured using an enzyme-linked immunoadsorbent assay in 121 consecutive patients with colorectal carcinoma and compared with TGF-beta1 serum levels in 31 healthy volunteers. Serum levels of TGF-beta1 also were measured in 50 patients who underwent curative surgical resection (part of the 121 preoperative patients) to compare their levels with preoperative serum levels of TGF-beta1.

RESULTS

Serum levels of TGF-beta1 in patients with colorectal carcinoma (45+/-15 ng/mL) (mean+/-the standard deviation) were significantly higher than those in the healthy control group (32+/-4 ng/mL) (P = 0.001). Serum levels of TGF-beta1 increased with increasing tumor stage (P < 0.01). Serum levels of TGF-beta1 were correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, and serum levels of carcinoembryonic antigen (CEA). Serum levels of TGF-beta1 tended to increase with increasing CEA (correlation coefficient = 0.21; P < 0.05). The mean serum level of TGF-beta1 in patients with colorectal carcinoma before surgery (45+/-14 ng/mL) (n = 50) significantly decreased to 34+/-7 ng/mL, which was within the normal range (32+/-4 ng/mL), after curative surgical resection of the tumor (P = 0.0000). Serum levels of TGF-beta1 after tumor resection decreased more significantly in patients with higher preoperative levels of TGF-beta1 (from 53+/-12 ng/mL to 36+/-6 ng/mL) (n = 30).

CONCLUSIONS

The results of the current study suggest that serum levels of TGF-beta1 in colorectal carcinoma patients may be associated with disease progression and may be used as a biomarker in the management of colorectal carcinoma patients. The authors believe further studies with a large number of patients for a longer follow-up period are necessary to conclude whether serum levels of TGF-beta1 carry significant clinical relevance.

The relationship between prognostic and predictive factors in the management of breast cancer

The discovery of new prognostic factors proceeds at a much more rapid pace than our knowledge of how to properly utilize this information in the management of patients with breast cancer, especially those with early breast cancer that has not metastasized to regional lymph nodes. Prognostic factors provide information on how the patient is likely to do regardless of treatment. Predictive factors provide information on whether a patient is likely to benefit from therapy. Most factors identified to date provide prognostic information, but relatively few provide information that is truly helpful in making a therapeutic decision in the management of individual patients. In large part this is because there has been insufficient study of the factor, especially prospective evaluations of the factor. Unfortunately this has resulted in the premature use of this information under the general rubric that patients with a poor prognosis deserve more treatment in spite of the fact that there may be no benefit from that therapy in the poor prognostic group.

Elevated serum levels of transforming growth factor-beta1 in patients with colorectal carcinoma: its association with tumor progression and its significant decrease after curative surgical resection

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) acts as a potent inhibitor of cell growth and tumor progression but loss of this negative regulation can contribute to tumor development. Some studies have reported an association between disease progression and TGF-beta1 expression in patients with colorectal carcinoma, but their results were not always consistent.

METHODS

Serum levels of TGF-beta1 were measured using an enzyme-linked immunoadsorbent assay in 121 consecutive patients with colorectal carcinoma and compared with TGF-beta1 serum levels in 31 healthy volunteers. Serum levels of TGF-beta1 also were measured in 50 patients who underwent curative surgical resection (part of the 121 preoperative patients) to compare their levels with preoperative serum levels of TGF-beta1.

RESULTS

Serum levels of TGF-beta1 in patients with colorectal carcinoma (45+/-15 ng/mL) (mean+/-the standard deviation) were significantly higher than those in the healthy control group (32+/-4 ng/mL) (P = 0.001). Serum levels of TGF-beta1 increased with increasing tumor stage (P < 0.01). Serum levels of TGF-beta1 were correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, and serum levels of carcinoembryonic antigen (CEA). Serum levels of TGF-beta1 tended to increase with increasing CEA (correlation coefficient = 0.21; P < 0.05). The mean serum level of TGF-beta1 in patients with colorectal carcinoma before surgery (45+/-14 ng/mL) (n = 50) significantly decreased to 34+/-7 ng/mL, which was within the normal range (32+/-4 ng/mL), after curative surgical resection of the tumor (P = 0.0000). Serum levels of TGF-beta1 after tumor resection decreased more significantly in patients with higher preoperative levels of TGF-beta1 (from 53+/-12 ng/mL to 36+/-6 ng/mL) (n = 30).

CONCLUSIONS

The results of the current study suggest that serum levels of TGF-beta1 in colorectal carcinoma patients may be associated with disease progression and may be used as a biomarker in the management of colorectal carcinoma patients. The authors believe further studies with a large number of patients for a longer follow-up period are necessary to conclude whether serum levels of TGF-beta1 carry significant clinical relevance.

Expression of epidermal growth factor receptor mRNA and protein in primary breast carcinomas

The expression of epidermal growth factor receptor (EGFR) mRNA and protein has been determined in a group of breast carcinomas and compared to oestrogen and progesterone receptor (ER, PgR) status, as well as pathological features. In situ hybridization using a digoxigenin-labelled oligonucleotide probe was applied to formalin-fixed paraffin-embedded sections, and immunohistochemistry was used to determine EGFR protein. EGFR mRNA was detected in 66% of carcinomas with a third having labelling similar to normal breast tissue, 22% heterogeneous weak to strong labelling, and 11% strong labelling. EGFR protein was detected in 36% and these tumours had a strong correlation to lack of ER and high histological grade. The presence of EGFR protein was strongly correlated with more intense labelling for EGFR mRNA (p < 0.0001). This contrasted with normal breast in which both EGFR protein and mRNA were present with varying degrees in both tumours and a normal breast control. The ER-/PgR- carcinomas showed the full range of EGFR mRNA labelling. It is postulated that oestrogen or oestrogen regulated proteins are involved in regulation of EGFR mRNA and protein. In a proportion of tumours lacking steroid receptors regulation is lost, leading to EGFR overexpression.

Role of epidermal-growth-factor receptor in tumor progression in transformed human mammary epithelial cells

The presence of epidermal-growth-factor receptors (EGFR) and of its ligands (TGFalpha and amphiregulin) in breast-cancer tissues suggests that they play a paracrine/autocrine role in tumor growth or progression. This hypothesis was tested on 3 cell lines, S2T2, NS2T2A and NS2T2A1. These epithelial cells are derived from a normal human breast-epithelial-cell culture transformed by SV40-T Ag, are of the same clonal origin, have respectively increasing levels of EGFR, TGFalpha, amphiregulin and of thymidine-kinase activity associated with increasing tumorigenic potential in nude mice (tumor intake and tumor volume). The monoclonal antibody MAb 425, which blocks ligands interaction with EGFR, reduced by more than 90% anchorage-independent growth of the most tumorigenic cells, NS2T2A1. Another anti-EGFR MAb, 528, reduced to 25% of controls the mean tumor mass after NS2T2A1 grafting in mice. Anti-sense RNA expression of EGFR in these cells confirmed the importance of this receptor in tumor progression, since it reduced significantly the tumor volume and tumor weight of NS2T2A1 cells to 16% of those in mock-transfected control cells.

Expression of growth factors, growth inhibiting factors, and their receptors in invasive breast cancer. I: An inventory in search of autocrine and paracrine loops

The aim of the present study was to investigate which growth factors, receptors, and growth inhibiting factors are expressed in invasive breast cancer. Five (angiogenic) growth factors and their receptors: platelet-derived growth factor A chain (PDGF-AA) and PDGF receptor alpha (PDGF alpha R), PDGF-BB and PDGF beta receptor, transforming growth factor alpha (TGF alpha) 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-1 (TGF beta 1) and (TGF beta 2) and their receptor couple transforming growth factor beta receptor I (TGF beta R-I) and TGF beta R-II; and basic fibroblast growth factor (bFGF) were stained by standard immunohistochemistry on frozen sections in 45 cases of invasive carcinoma of the breast. Staining was scored as negative or positive in tumour epithelium, stroma, and blood vessels. TGF beta 1 and TGF beta 2 were expressed in the tumour cells in 67 per cent and 76 per cent of cases, respectively, whereas PDG beta R and TGF beta R-II were expressed in 0 per cent and 2 per cent, respectively. The other factors showed variable expression in tumour cells. All factors were expressed in the stroma in most cases, except Flt-1, Flk-1/KDR, TGF beta 2, and TGF beta R-II, which showed variable expression, and EGFR, which showed no expression. The endothelium was in most cases positive for bFGF, PDGF-AA, PDGF-BB, VEGF, PDGF alpha R, PDGF beta R, and TGF beta 1 but TGF beta/ was negative in most cases and TGF alpha, EGFR, Flt-1, Flk-1/KDR, TGF beta R-I, and TGF beta R-II were variably expressed. The most interesting possible auto/paracrine loops, as demonstrated on serial sections and by fluorescence double staining, were the TGF alpha/EGFR, TGF beta s/TGF beta R, VEGF/Flt-1, and the VEGF/Flk-1 combinations. In conclusion, growth factors, growth inhibiting factors, and their receptors are frequently expressed in invasive breast cancer. Indications for some possible auto- and paracrine loops have been found, which should encourage further study on the role of these factors in breast cancer proliferation and angiogenesis.

Transforming growth factor-beta1 enhances the invasiveness of human MDA-MB-231 breast cancer cells by up-regulating urokinase activity

Transforming growth factor-beta (TGFbeta1) enhances human MDA-MB-231 breast tumour cell invasion of reconstituted basement membrane in vitro but does not inhibit proliferation of this cell line. In contrast to basal invasion, which is plasmin-, urokinase (uPA)-, tissue-type plasminogen activator (t-PA)-, matrix metalloproteinase (MMP)-9- and TIMP-1-inhibitable MMP-dependent, TGFbeta1 enhanced-invasion is dependent upon plasmin and uPA activity but does not appear to involve t-PA-, MMP9- or TIMP-1-inhibitable MMPs, as judged by inhibitor studies. Enhanced invasion is associated with increased u-PA, UPAR, PAI-1, MT-MMP-1, MMP-9 and TIMP-1 expression; with reduced t-PA, MMP-1 and MMP-3 expression; and with the induction of membrane MMP-9 association. The net result of these changes includes increased secreted, but not membrane-associated, uPA levels and activity and reduced secreted levels of plasmin and APMA-activatable gelatinolytic, collagenolytic and caseinolytic MMP activity but no change in membrane-associated gelatinolytic activity, despite increased MT-MMP-1 expression and MMP-9 membrane association. TGFbeta1 does not induce MMP-2 expression. Our data indicate that TGFbeta1 can promote the malignant behaviour of MDA-MB-231 cells refractory to TGFbeta1-mediated proliferation control by enhancing their invasive capacity. We suggest that this results from the action of a uPA/plasmin-dependent mechanism resulting from stimulation of uPA expression, secretion and subsequent activity, despite elevated PAI-1 inhibitor levels.

Expression of growth factors, growth-inhibiting factors, and their receptors in invasive breast cancer. II: Correlations with proliferation and angiogenesis

Growth factors may play an important role in tumour growth and angiogenesis by their influence on tumour cell proliferation or their effect on neovascularization. The aim of the present study was to determine which of the growth factors, growth-inhibiting factors, and their receptors investigated in a previous study are correlated with proliferation and angiogenesis in invasive breast cancer, with emphasis on the impact of possible autocrine and paracrine loops. Five growth factors and their receptors: platelet-derived growth factor A chain (PDGF-AA) and PDGF alpha receptor (PDGF alpha R), PDGF-BB and PDGF beta receptor (PDGF beta R), transforming growth factor alpha (TGF alpha) and its receptor epidermal growth factor receptor (EGFR), and vascular endothelial growth factor (VEGF) and its receptors (Flt-1 and Flk-1/KDR; two growth-inhibiting factors: transforming growth factor beta-1 (TGF beta 1) and TGF beta 2 and their receptor couple TGF beta R-I and TGF beta R-II; and basic fibroblast growth factor (bFGF) were stained in 45 cases of invasive breast cancer by standard immunohistochemistry on frozen sections. Staining in tumour cells, stromal cells, and endothelial cells was scored as negative or positive. Proliferation was determined by assessment of the mitotic activity index (MAI) and the degree of angiogenesis was measure by counting the number of microvessels (microvessel density: MVD) in the most vascularized area of the tumour. bFGF and EGFR showed positive correlations with the MAI, while TGF beta 2 showed a negative correlation. Expression of bFGF, TGF alpha, TGF beta 2, and EGFR correlated positively with the MVD. Co-expression of the TGF alpha/EGFR growth factor/receptor combination showed a stronger correlation with the MAI and the MVD than EGFR or TGF alpha alone, and the TGF beta 2/TGF beta R-I/TGE beta R-II combination showed a positive correlation with the MVD. In conclusion, the expression of several growth factors, growth factor receptors and growth-inhibiting factors showed correlations with the rate of proliferation and the degree of angiogenesis in invasive breast cancer. Some growth factor/receptor combinations showed stronger correlations with proliferation and angiogenesis than the growth factor or receptor alone, pointing to the importance of possible auto- and paracrine loops for stimulation of proliferation and angiogenesis by growth factors and their receptors.

Expression of growth factors, growth inhibiting factors, and their receptors in invasive breast cancer. I: An inventory in search of autocrine and paracrine loops

The aim of the present study was to investigate which growth factors, receptors, and growth inhibiting factors are expressed in invasive breast cancer. Five (angiogenic) growth factors and their receptors: platelet-derived growth factor A chain (PDGF-AA) and PDGF receptor alpha (PDGF alpha R), PDGF-BB and PDGF beta receptor, transforming growth factor alpha (TGF alpha) 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-1 (TGF beta 1) and (TGF beta 2) and their receptor couple transforming growth factor beta receptor I (TGF beta R-I) and TGF beta R-II; and basic fibroblast growth factor (bFGF) were stained by standard immunohistochemistry on frozen sections in 45 cases of invasive carcinoma of the breast. Staining was scored as negative or positive in tumour epithelium, stroma, and blood vessels. TGF beta 1 and TGF beta 2 were expressed in the tumour cells in 67 per cent and 76 per cent of cases, respectively, whereas PDG beta R and TGF beta R-II were expressed in 0 per cent and 2 per cent, respectively. The other factors showed variable expression in tumour cells. All factors were expressed in the stroma in most cases, except Flt-1, Flk-1/KDR, TGF beta 2, and TGF beta R-II, which showed variable expression, and EGFR, which showed no expression. The endothelium was in most cases positive for bFGF, PDGF-AA, PDGF-BB, VEGF, PDGF alpha R, PDGF beta R, and TGF beta 1 but TGF beta/ was negative in most cases and TGF alpha, EGFR, Flt-1, Flk-1/KDR, TGF beta R-I, and TGF beta R-II were variably expressed. The most interesting possible auto/paracrine loops, as demonstrated on serial sections and by fluorescence double staining, were the TGF alpha/EGFR, TGF beta s/TGF beta R, VEGF/Flt-1, and the VEGF/Flk-1 combinations. In conclusion, growth factors, growth inhibiting factors, and their receptors are frequently expressed in invasive breast cancer. Indications for some possible auto- and paracrine loops have been found, which should encourage further study on the role of these factors in breast cancer proliferation and angiogenesis.

Study of tumor infiltrating lymphocytes and transforming growth factor-beta as prognostic factors in breast carcinoma

Cytokines and growth factors are powerful modulators of the immune response. Their aberrant expression either by the tumor cells or by the tumor infiltrating lymphocytes confers a selective advantage to the tumor to grow and suppress the cytotoxic activity of the infiltrating lymphocytes. Therefore, analysis of these soluble factors in the tumor microenvironment can provide an insight into the understanding of the tumor behavior and may be used as a prognostic factor. In the present study the nature of the tumor infiltrating lymphocytes (TILs) and cytokine profile was examined in 36 and 19 mammary carcinoma tissues, respectively, by immunohistochemistry and PCR. Phenotypic differences in the number of cytotoxic T lymphocytes (CD8+) and lymphokine activated killer cells (CD16) was observed among TILs when patients with either early disease stage (39% and 46.6%, respectively) or those alive with no residual disease (31% and 52%, respectively) were compared with late stage (9.7% and 22.8%, respectively) or those dead of disease (14.6% and 15.6%, respectively). Furthermore, analysis of the 19 tumor samples for cytokine mRNA expression by RT-PCR revealed the presence of TNF-alpha, IL-10, TGF-beta1, and IL-2. However, semi-quantitative PCR analysis demonstrated TGF-beta1 expression to be significantly higher in patients with a favorable outcome (1.0246 attomoles/micromoles) as compared to patients with a poor prognosis (0.1157 attomoles/micromoles). Our results demonstrate the potential biological significance of certain host factors, particularly TILs and TGFbeta1 expression, on the outcome of breast cancer.

EGF-related peptides in the pathophysiology of the mammary gland

Normal mammary gland development is the result of complex interactions between a number of hormones and growth factors. Normal and malignant human mammary epithelial cells are able to synthesize and to respond to various different, locally acting growth factors and growth inhibitors. Among these, the EGF-related peptides play an important role in regulating the proliferation and differentiation of human mammary epithelial cells. EGF4 and TGF4 are able to stimulate the lobulo-alveolar development of the mammary gland in vivo as well they are involved in the pathogenesis of human breast cancer. Experimental evidence suggests that estrogen-induced proliferation of breast carcinoma cells is mediated in part by EGF-related growth factors. It has also been demonstrated that activation of certain cellular protooncogenes such as c-Ha-ras in human mammary epithelial cells results in cellular transformation and in an increased production of several EGF-related growth factors such as TGFalpha and amphiregulin. Coexpression of both EGF-related peptides and their own receptors frequently occurs in human breast carcinomas and in human breast cancer cell lines, suggesting that an autocrine pathway of uncontrolled cell growth sustains neoplastic transformation.

The epidermal growth factor receptor in breast cancer

The epidermal growth factor receptor (EGFR)3 is a 170 kD transmembrane tyrosine kinase activated by several ligands. It is required for normal mammary development and lactation and is aberrantly expressed in approximately 40% of breast carcinomas, particularly those with a poor prognostic phenotype. Since EGF receptor levels are elevated in a high proportion of many tumor types its potential as a therapy target is being investigated using the EGF receptor to target toxins, as well as drugs that interfere with signaling and anti-receptor antibodies. These approaches are likely to be most effective when used in the adjuvant situation in combination with chemotherapy.

Role of TGF beta in the anti-estrogen response/resistance of human breast cancer

Transforming growth factor beta (TGF beta) has potent inhibitory effects upon epithelial proliferation and malignant progression may be associated with breakdown of the autocrine and paracrine inhibitory loops in which TGF beta participates. The therapeutic effecs of anti-estrogens may be partially attributable to boosting of local endogenous levels of TGF beta. This article reviews the evidence in support of TGF beta being a proximate effector in mediation of the anti-neoplastic effects of anti-estrogens. Both the conventional estrogen receptor (ER) dependent and ER independent mechanisms of action are likely to be involved. Evidence for preferential stromal induction of TGF beta by anti-estrogens is emphasized, together with the therapeutic potential of this strategy for improving outcome in early breast cancer irrespective of ER status.

In situ cytokine production by breast cancer tumor-infiltrating lymphocytes

BACKGROUND

Human breast cancers progressively grow despite the presence of extensive lymphocytic infiltration and specific antitumor immune recognition, thereby calling into question the competency of breast tumor-infiltrating lymphocytes (TIL). The function of breast TILs in vivo and their possible role in the suppression of an antitumor immune response are largely unknown.

METHODS

The cytokines produced in situ by lymphocytes in 89 breast carcinomas and 14 benign breast lesions were assessed using immunohistochemistry.

RESULTS

The majority of tumor and benign breast samples contained T-cell infiltrates, which were disclosed using an anti-CD3 antibody stain. The percentage of tumor samples in which > or =3% of the lymphocytes were producing cytokines was as follows: interleukin (IL)-2 45%, IL-4 36%, tumor necrosis factor-alpha (TNF-alpha) 28%, transforming growth factor-beta 1 (TGF-beta 1) 20%, IL-10 11%, interferon-gamma (IFN-gamma) 4%, and granulocyte-macrophage colony-stimulating factor (GM-CSF) 3%. Production of IL-2, IL-4, and TGF-beta 1 by TILs in breast cancers exceeded that detected in benign breast lesions (p < 0.005). Significantly more tumor samples contained lymphocytes producing IL-2, IL-4, TGF-beta 1, and TNF-alpha than IFN-gamma and GM-CSF (p < 0.002 for each comparison). One or more of the potentially immunoinhibitory cytokines-IL-4, IL-10, or TGF-beta 1-were produced by lymphocytes in 44% of the specimens. No significant associations were seen between lymphocyte production of a particular cytokine and disease-free survival (median follow-up 43 months).

CONCLUSIONS

Immunohistochemical techniques can be used to detect cytokine secretion by TILs in preserved tissue. The relative lack of secretion of IFN-gamma and GM-CSF, rather than a deficiency of IL-2, may explain why the antitumor immune response to breast cancer is impaired.

Hepatocyte growth factor/scatter factor expression and c-met in primary breast cancer

Hepatocyte growth factor/scatter factor (HGF/SF) is a fibroblast-derived cytokine whose receptor is encoded by c-met. Activation of c-met promotes tumour cell proliferation, dissociation, invasiveness and angiogenesis. Aberrant expression of HGF/SF or c-met may play a role in tumour progression. HGF/SF and c-met were determined in 73 breast cancers (median follow up: 61 months) and 10 samples of tumour-free breast tissue. HGF/SF was detected at significantly higher concentrations in breast cancers (median 350, range 58-1604 ng per 100 mg total protein) when compared with normal breast tissue (median 108, range 66-213 ng per 100 mg total protein) (P < 0.001). C-met was detected in all 10 samples of tumour-free breast tissue and in 26 breast cancers. HGF/SF concentrations correlated with disease relapse (P < 0.001) and reduced overall survival (P < 0.001). Tumours with detectable c-met correlated significantly with disease-relapse (P = 0.012). Multivariate analysis demonstrated a significant interaction between HGF/SF and c-met in relation to disease-relapse (P = 0.014). These results suggest a biological interaction involving HGF/SF and c-met in promoting tumour progression in breast cancer.

Prognostic significance of TGF-alpha expression in breast cancer

A series of breast cancer biopsies from 204 women were analysed immunohistochemically for the expression of transforming growth factor alpha (TGF-alpha). Expression of TGF-alpha was intense in 119 cases (58%), weak in 63 (31%), and totally absent in 22 (11%) of the cases. No correlation was observed between the expression of TGF-alpha and tumour size, metastasis at diagnosis, histological type and grade, ER and PR status, DNA index, S-phase fraction or the expression of TGF-beta1 or beta2. However, the expression of TGF-alpha was significantly related to axillary lymph node metastasis and to low survival probability during the follow-up. These data support the earlier observations on the in vitro studies, suggesting that TGF-alpha most probably exerts an in vivo growth stimulation of female breast cancer cells.