Metalloproteinases and tissue inhibitors of metalloproteinases

The Effect of Irisin on Proliferation, Apoptosis, and Expression of Metastasis Markers in Prostate Cancer Cell Lines

INTRODUCTION

Irisin is a newly discovered myokine released from skeletal muscle during exercise. The matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that play a key role in the metastatic process via degrading extracellular matrix. The aim of this study was to investigate the effect of irisin on expression of metastatic markers MMP2 and MMP9 and induced apoptosis in human prostate cancer cells.

METHODS

In this study, we examined the effect of different concentrations of irisin on induced apoptosis and cell viability of two cell lines, LNCaP and DU-145, by using flow cytometry and MTT assay, respectively. The expression of MMP2 and MMP9 genes was also analyzed by real-time PCR after irisin treatment. Data were analyzed using the comparative cycle threshold 2^-∆∆Ct method.

RESULTS

Cell viability was reduced in both LNCaP and DU-145 cell lines at different concentrations of irisin. However, this decreased cell viability was strongly significant (p < 0.05) only at 5 and 10 nM concentrations of irisin in the LNCaP cell line. Furthermore, irisin could induce apoptosis in both cell lines at a concentration of 10 nM compared to 5 nM. Real-time PCR results also demonstrated a decreased expression in MMP2 and MMP9 genes in a concentration-dependent manner in both cell lines.

CONCLUSION

These results showed the anticancer effects of irisin on cell viability of both LNCaP and DU-145 cell lines and also on the expression of MMP2 and MMP9 genes occurred in a dose- and time-dependent manner.

Multi-layered proteogenomic analysis unravels cancer metastasis directed by MMP-2 and focal adhesion kinase signaling

The role of matrix metalloproteinase-2 (MMP-2) in tumor cell migration has been widely studied, however, the characteristics and effects of MMP-2 in clinical sample of metastatic colorectal cancer (CRC) remain poorly understood. Here, in order to unveil the perturbed proteomic signal during MMP-2 induced cancer progression, we analyzed plasma proteome of CRC patients according to disease progression, HCT116 cancer secretome upon MMP-2 knockdown, and publicly available CRC tissue proteome data. Collectively, the integrative analysis of multi-layered proteomes revealed that a protein cluster containing EMT (Epithelial-to-Mesenchymal Transition)-associated proteins such as CD9-integrin as well as MMP-2. The proteins of the cluster were regulated by MMP-2 perturbation and exhibited significantly increased expressions in tissue and plasma as disease progressed from TNM (Tumor, Node, and Metastasis) stage I to II. Furthermore, we also identified a plausible association between MMP-2 up-regulation and activation of focal adhesion kinase signaling in the proteogenomic analysis of CRC patient tissues. Based on these comparative and integrative analyses, we suggest that the high invasiveness in the metastatic CRC resulted from increased secretion of MMP-2 and CD9-integrin complex mediated by FAK signaling activation.

Selected Metal Matrix Metalloproteinases and Tissue Inhibitors of Metalloproteinases as Potential Biomarkers for Tubulointerstitial Fibrosis in Children with Unilateral Hydronephrosis

Renal tubulointerstitial fibrosis caused by congenital ureteropelvic junction obstruction (UPJO) may lead to the development of obstructive nephropathy (ON) and the impairment of kidney function. Hence, the identification of early biomarkers of this condition might be of assistance in therapeutic decisions. This study evaluates serum and urinary metalloproteinases MMP-1, MMP-2, and MMP-9 and tissue inhibitors of metalloproteinases TIMP-1 and TIMP-2 as potential biomarkers of ON in children with congenital unilateral hydronephrosis (HN) caused by UPJO. Forty-five (45) children with congenital HN of different grades of severity and twenty-one (21) healthy controls were enrolled in the study. Urinary and serum concentrations of MMP-1, MMP-2, MMP-9, TIMP-1 and TIMP-2 were measured using specific ELISA kits. The urinary excretions were expressed as biomarker/creatinine (Cr) ratios. To evaluate the extracellular matrix remodelling process activity, the serum and urinary MMP-1, -2, -9/TIMP-1, -2 ratios were also calculated. In comparison with the controls, patients with HN, independent of the grade, showed significantly increased median serum MMP-9, TIMP-1, and TIMP-2, median urinary MMP-9/Cr, and TIMP-2/Cr ratios. Lower median values of serum MMP-2/TIMP-1, MMP-9/TIMP-1 in patients with HN were also revealed. Additionally, higher urinary MMP-2/Cr, lower urinary MMP-2/TIMP-2, and lower serum MMP-9/TIMP-2 ratios were observed in patients with HN grades 3 and 4. Patients with ON diagnosed by renal scintigraphy had a significantly higher median serum MMP-9 concentration and lower median serum MMP-9/TIMP-1, -2 ratios in comparison with those without this condition. Patients with nonglomerular proteinuria had a significantly higher median serum TIMP-1 concentration, a higher median urinary TIMP-2/Cr ratio, and a lower serum MMP-9/TIMP-1 ratio compared to those without this symptom. The relationship between the measured biomarkers and the relative function of the obstructed kidney showed no correlations. The ROC curve analysis showed a promising diagnostic profile for the detection of ON for serum MMP-9 and the serum MMP-9/TIMP-1 and MMP-9/TIMP-2 ratios. In conclusion, the results of this study suggest that patients with HN, particularly with grades 3 and 4, are at higher risk of renal tubulointerstitial fibrosis. The noninvasive markers of this condition considered are urinary MMP-2/Cr and MMP-9/Cr, serum MMP-9, serum and urinary MMP-2, MMP-9/TIMP-1, -2. Additionally, serum MMP-9 and MMP-9/TIMP-1, -2 may become promising markers of ON.

Differential expression of Ets-1 in breast cancer among North Indian population

Breast cancer is a highly aggressive disease contributing to high mortality rate among females across the globe owing to wide geographical variations, change in lifestyle along with rapid tumor growth, drug resistance, and high metastasis rate. To understand the molecular and genetic basis of breast cancer progression; we studied the role of E26 transformation-specific-1 (Ets-1) transcription factor which is implicated to have a role in carcinogenesis like invasion, metastasis, angiogenesis, etc. Our findings revealed an overexpression of Ets-1 gene in 75 breast cancer tumors as compared with their normal adjacent tissues. The findings significantly established a co-relation between Ets-1 expression in breast cancer tissue with hormonal receptor profiles and ductal-lobular histological subtypes in Indian population. In addition, a differential expression pattern of Ets-1 was observed between high, moderate, and low grades of breast cancer patients. The present study demonstrates a crucial role of Ets-1 transcription factor which may serve as a potential biomarker for breast carcinogenesis.

MMP-9 Overexpression Due to TIMP-1 and RECK Underexpression is Associated with Prognosis in Prostate Cancer

Background

Extracellular matrix homeostasis is strictly maintained by a coordinated balance between the expression of metalloproteinases (MMPs) and their inhibitors. The purpose of this study was to investigate whether the expression of MMP-9 and its specific inhibitors, TIMP-1 and RECK, are expressed in a reproducible, specific pattern and if the profiles are related to prognosis and clinical outcome in prostate cancer (PC).

Methods

MMP-9, TIMP-1, and RECK expression levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) in fresh-frozen malignant tissue specimens collected from 79 patients with clinically localized PC submitted to radical prostatectomy (RP). Frozen benign prostatic tissue from another 10 men with prostate cancer, also submitted to RP, was analyzed to determine if the profile of gene expression was maintained. The control group consisted of 11 patients with benign prostate hyperplasia (BPH).

Results

In the tumor samples, MMP-9 was overexpressed by 9.2 times, and TIMP-1 and RECK were underexpressed (0.75 and 0.80 times, respectively). Overexpression of MMP-9 was significantly related to PSA levels above 10 ng/mL (p=0.033). In addition, MMP-9 overexpression was related to biochemical recurrence, with a marginal statistical significance (p=0.089). MMP-9 was also overexpressed in benign tissues of patients with PC, as were TIMP-1 and RECK, in contrast to their underexpression in tumor samples.

Conclusion

Our results show that MMP-9 is overexpressed and its negative regulators are underexpressed in PC tissue, emphasizing a possible role of MMP-9 in the carcinogenesis process. Additionally, we noticed a relationship between MMP-9 overexpression and increased levels of PSA, an important prognostic factor. In benign tissue adjacent to tumors, the MMP-9 equilibrium is likely maintained because the expression of its negative regulators is preserved.

MMP9 overexpression is associated with good surgical outcome in children with UPJO: Preliminary results

BACKGROUND

Ureteropelvic junction obstruction (UPJO) diagnosed prenatally occurs in 1:150 - 1:1200 pregnancies. Although many studies investigating the molecular changes of this obstructed segment have been performed, the underlying mechanisms are still unclear. The role of extracellular matrix (ECM) components remains controversial, and the investigations in the field of ECM changes, might help the better understanding of the pathogenesis of this common condition. The aim of the present study was to investigate for the first time in the literature whether MMP9 and its specific inhibitors, TIMP1 and RECK, are expressed in a reproducible, specific pattern in UPJ.

METHODS

UPJO specimens were obtained from 16 children at the time of dismembered pyeloplasty due to intrinsic UPJ stenosis. Expression levels of the three genes (MMP9, TIMP1 and RECK) were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). Then correlated the expression levels of the genes according to grade study population that was divided in 2 categories according to Society of Fetal Urology classification, grade 3 (moderate) and 4 (severe). For DTPA we subdivided the childrens in 2 groups, obstructive (T 1/2 more than 20 min) and partial obstructive (T 1/2 between 10 and 20 min) and success in a surgery was defined as decrease in T 1/2 to less than 20 min, absence of symptoms, improving renal function and decreasing dilatation on successive exams.

RESULTS

MMP9 was underexpressed and TIMP1 and RECK were overexpressed in children with obstructive DTPA but the differences were not statistically significant. Overexpression of MMP9 was higher among patients with severe grade of UPJ compared to those with moderate grade. Surprisingly expression levels of MMP-9 was three times higher in children who were successfully treated by surgery (n = 10) (p = 0.072), so those who were followed for at least 1 year after surgery and remained with improvement in renal function and decreasing dilation on intravenous urogram and TIMP-1 was underexpressed in 100 % of this cases (p = 0.00).

CONCLUSIONS

We showed an increase in expression of MMP9 and a decrease in expression of TIMP1 in children who improving renal function and decreasing dilation after surgery. We believe that the higher expression of MMP9 in these cases can reflect an increase in degradation and remodeling process that could be used as a marker for surgical outcome.

Loss of TIMP-1 immune expression and tumor recurrence in localized prostate cancer

Introduction and objective:

Overexpression of MMPs has been related to biochemical recurrence after radical prostatectomy. TIMP1 and TIMP2 are controllers of MMPs and the aim of this study is to evaluate the expression levels of MMPs and their regulators using immunohistochemistry in tissue microarray of localized prostate cancer (PC).

Materials and Methods:

Immune-expression of MMP-9, MMP-2, TIMP1, TIMP-2, MMP-14 and IL8, were analyzed by immunohistochemistry in radical prostatectomy specimens of 40 patients with localized PC who underwent surgery between September 1997 and February 2000. Protein expression was considered as categorical variables, negative or positive. The results of the immune-expression were correlated to Gleason score (GS), pathological stage (TNM), pre-operatory PSA serum levels and biochemical recurrence in a mean follow up period of 92.5 months.

Results:

The loss of TIMP1 immune-expression was related to biochemical recurrence. When TIMP1 was negative, 56.3% patients recurred versus 22.2% of those whose TIMP1 was positive (p=0.042). MMP-9, MMP-2, IL8 and MMP-14 were positive in the majority of PC. TIMP-2 was negative in all cases.

Conclusion:

Negative immune-expression of TIMP1 is correlated with biochemical recurrence in patients with PC possibly by failing to control MMP-9, an important MMP related to cancer progression.

Stromal matrix metalloproteinase 2 regulates collagen expression and promotes the outgrowth of experimental metastases

Breast cancer survival rates decrease from 99% for patients with local disease to 25% for those with distant metastases. Matrix metalloproteinases (MMPs), including MMP2, are associated with metastatic progression. We found that loss of host MMP2 reduces the proliferation of experimental metastases in the lungs and identified fibroblasts in tumour-bearing lungs as the major source of MMP2. In vitro, spheroidal mammary tumour growth was increased by co-culture with control fibroblasts isolated from tumour-bearing lungs, but not when fibroblasts with stable Mmp2 knockdown were used. This result prompted us to assess whether MMP2 was responsible for a tumour-proliferative, activated fibroblast phenotype. To test this, we evaluated: (a) fibroblasts from wild-type tumour-bearing lungs, with or without shRNA-mediated MMP2 knockdown; and (b) normal, quiescent fibroblasts isolated from either WT or Mmp2(-/-) mice. Quantitative PCR revealed that Mmp2 knockdown attenuated expression of two markers of activation (α-smooth muscle actin and vimentin), but there was minimal expression in quiescent WT or Mmp2(-/-) fibroblasts, as expected. Placing quiescent fibroblasts under activating conditions led to increases in activation-associated transcripts in WT but not Mmp2(-/-) fibroblasts. Additionally, Mmp2 knockdown fibroblasts showed significantly decreased expression of the matrix transcripts collagen I, collagen IV and fibronectin. Addition of active TGFβ was sufficient to rescue the MMP2-dependent collagen I and IV expression, while MMP2-induced collagen expression was blocked by the addition of TGFβ1-neutralizing antibody. Gene expression data in stromal cells of human breast cancers reveal that MMP2 expression is also positively correlated with activation and matrix transcripts. Thus, we present a model whereby MMP2 production in tumour fibroblasts is important for TGFβ1 activity and subsequent activation of fibroblasts to a matrix-producing, proliferation-supportive phenotype. Overall, our results reveal a previously undefined role for MMP2 in metastatic outgrowth mediated by fibroblasts, and extend the mechanisms by which MMPs contribute to tumour progression.

Association of Fascin and matrix metalloproteinase-9 expression with poor prognostic parameters in breast carcinoma of Egyptian women

Abstract

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1421167695121127.

Expression of MiR200a, miR93, metastasis-related gene RECK and MMP2/MMP9 in human cervical carcinoma--relationship with prognosis

AIM AND BACKGROUND

Cervical cancer remains the third most common cancer in women globally after breast and colorectal cancer. Well-characterized biomarkers are necessary for early diagnosis and to predict metastatic progression and effective therapy. MiRNAs can regulate gene expression, cell growth, differentiation and apoptosis by targeting mRNAs for translational repression or degradation in tumor cells. The present study was conducted to assess expression of miR93, miR200a, RECK, MMP2, MMP9 in invasive cervical carcinoma, and analyze their clinical significance.

METHOD

A total of 116 patients with invasive cervical carcinoma and 100 patients undergoing hysterectomy for benign lesions were retrospectively examined. Quantitative real-time PCR was performed to determine expression of miR93 and miR200a while RECK, MMP2, MMP9 and MVD were assessed by immunohistochemical staining.

RESULTS

Cervical carcinoma patients demonstrated up-regulation of miR-93, miR-200a, MMP2 and MMP9, with down-regulation of RECK as compared to benign lesion tissues. RECK was significantly inversely related to invasion and lymphatic metastasis. The 5-year survival rate for patients with strong RECK expression was significantly higher than that with weakly expressing tumors.

CONCLUSION

MiR-93 and miR-200a are associated with metastasis and invasion of cervical carcinoma. Thus together with RECK they are potential prognostic markers for cervical carcinoma. RECK cooperating with MMP2, MMP9 expression is a significant prognostic factor correlated with long-term survival for patients with invasive cervical carcinoma.

Underexpression of MMP-2 and its regulators, TIMP2, MT1-MMP and IL-8, is associated with prostate cancer

OBJECTIVE

Extracellular matrix homeostasis is strictly maintained by a coordinated balance between the expression of metalloproteinases (MMPs) and their regulators. The purpose of this study was to investigate whether MMP-2 and its specifi c regulators, TIMP-2, MT1-MMP and IL-8, are expressed in a reproducible, specific pattern and if the profiles are related to prognosis and clinical outcome of prostate cancer (PCa).

MATERIALS AND METHODS

MMP-2, TIMP-2, MT1-MMP and IL-8 expression levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) in freshly frozen malignant and benign tissue specimens collected from 79 patients with clinically localized PCa who underwent radical prostatectomies. The control group consisted of 11 patients with benign prostate hyperplasia (BPH). The expression profile of the MMP-2 and its regulators were compared using Gleason scores, pathological stage, pre-operative PSA levels and the fi nal outcome of the PCa.

RESULTS

The analysis of 79 specimens of PCa revealed that MMP-2, TIMP-2, MT1-MMP and IL-8 were underexpressed at 60.0%, 72.2%, 62.0% and 65.8%, respectively, in malignant prostatic tissue in relation to BPH samples. Considering the prognostic parameters, we demonstrated that high Gleason score tumors (≥ 7) overexpressed MMP-2 (p = 0.048) and TIMP-2 (p = 0.021), compared to low Gleason score tumors (< 7).

CONCLUSION

We have demonstrated that MMP-2 and its regulators are underexpressed in PCa. Alternatively, overexpression of MMP-2 and TIMP-2 was related to higher Gleason score tumors. We postulate that alterations in metalloproteinase expression may be important in the control of tissue homeostasis related to prostate carcinogenesis and tumor behavior.

Evaluation of MMP-9 and TIMP-1 Levels of the Patients with Nasal Polyposis After Corticosteroid Therapies

The aim of this study is to evaluate the effects of intrapolyp, systemic and local corticosteroid treatment modalities on MMP-9 and TIMP-1 level in polyp tissues. This study included 71 patients and five groups. Group A treated with oral methylprednisolone, Group B, treated with topical steroid spray, Group C treated with intralesional triamcinolone acetonide, Group D patients with nasal polyposis who has not given any medication, Group E had surgery for concha bullosa without nasal polyp disease. Samples from group A were collected endoscopically 1 day after treatment was stopped. Group B samples were collected at the end of the first month. Video guided sample collection from Group C was also performed on the 7th day after treatment. MMP-9 and TIMP-1 levels were measured by Enzyme-linked immunosorbent assay method. When we compared the MMP-9 levels of all groups, there were no significant differences. There was significant difference of TIMP-1 level between Groups C and E (pC-E = 0.0019), however there was no difference among the level of the other groups. When MMP-9/TIMP1 rates of all groups were compared, there were significant difference between Group A and D (pA-D = 0.005) and between Group A and E, also between Group C and E. Our study is the first study to evaluate the effects of different corticosteroid treatment modalities on MMP-9 and TIMP-1 in nasal polyps and concluded that corticosteroid did not do a significant impact on this pathway.

MicroRNAs and metastasis-related gene expression in Egyptian breast cancer patients

AIM AND BACKGROUND

MicroRNAs (miRNAs) are a class of naturally occurring small noncoding RNAs that regulate gene expression, cell growth, differentiation and apoptosis by targeting mRNAs for translational repression or cleavage. The present study was conducted to study miRNAs in Egyptian breast cancer (BC) and their relation to metastasis, tumor invasion and apoptosis in addition to their association with the ER and PR statuses.

METHODS

Real Time RT-PCR was performed to identify the miRNA expression level of eight miRNAs and eight metastatic-related genes in 40 breast cancer samples and their adjacent non-neoplastic tissues. The expression levels of each miRNA relative to U6 RNA were determined. Also, miRNA expression profiles of the BC and their corresponding ANT were evaluated.

RESULTS

The BC patients showed an up-regulation in miRNAs (mir-155, mir-10, mir-21 and mir-373) with an upregulation in MMP2, MMp9 and VEGF genes. We found down regulation in mir-17p, mir-126, mir-335, mir-30b and also TIMP3, TMP1 and PDCD4 genes in the cancer tissue compared to the adjacent non-neoplastic tissues. Mir -10b, mir -21, mir-155 and mir373 and the metastatic genes MMP2, MMP9 and VEGF were significantly associated with an increase in tumor size (P<0.05). No significant difference was observed between any of the studied miRNAs regarding lymph node metastasis. Mir-21 was significantly over-expressed in ER-/PR- cases.

CONCLUSION

Specific miRNAs (mir-10, mir-21, mir-155, mir-373, mir-30b, mir-126, mir-17p, mir-335) are associated with tumor metastasis and other clinical characteristics for BC, facilitating identification of individuals who are at risk.

Increased expression of MMP-9 and IL-8 are correlated with poor prognosis of Bladder Cancer

Background

Extracellular matrix homeostasis is strictly maintained by a coordinated balance between the expression of metalloproteinases (MMPs) and their inhibitors. The purpose of this study was to investigate whether the expression of MMP-9, MMP-2 and its specific inhibitors, are expressed in a reproducible, specific pattern and if the profiles are related to prognosis in Bladder Cancer (BC).

Methods

MMP-9, MMP-2 and its specific inhibitors expression levels were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) in fresh-frozen malignant tissue collected from 40 patients with BC submitted to transurethral resection of bladder. The control group consisted of normal bladder tissue from five patients who had undergone retropubic prostatectomy to treat benign prostatic hyperplasia.

Results

MMP-9 was overexpressed in 59.0 % of patients, and MMP-2, TIMP-1, TIMP-2, MMP-14, RECK and IL-8 was underexpressed in most of the patients. Regarding prognostic parameters we observed that high-grade tumors exhibited significantly higher levels of MMP-9 and IL-8 (p = 0.012, p = 0.003). Invasive tumors (pT1-pT2) had higher expression levels of MMP-9 than superficial tumors (pTa) (p = 0.026). The same was noted for IL-8 that was more expressed by invasive tumors (p = 0.015, p = 0.048). Most importantly tumor recurrence was related with higher levels of both MMP-9 (p = 0.003) and IL-8 (p = 0.005).

Conclusion

We have demonstrated that the overexpression of MMP-9 and higher expression of IL-8 are related to unfavorable prognostic factors of urothelial bladder cancer and tumor recurrence and may be useful in the follow up of the patients.

Significant relation of tissue inhibitor of matrix metalloproteinase-2 and its combination with matrix metalloproteinase-2 to survival of patients with cancer of uterine cervix

Tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) has high affinity for matrix metalloproteinase-2 (MMP-2). Few studies simultaneously investigate their implication in prognosis of patients with cervical cancer. We used reverse transcription-polymerase chain reaction and immunohistochemical method for cervical tissues and microarrays to investigate the association among TIMP-2, MMP-2, clinicopathological parameters, and prognosis of patients with cancer. Our results showed that cancer tissues exhibited less TIMP-2 expression and patients with pelvic lymph node metastasis had less TIMP-2 expression. Positive TIMP-2 constellated with negative MMP-2 indicated lower recurrence probability and better overall survival. The protective effect of TIMP-2 expression may overcome the adverse effect of MMP-2 expression in terms of disease-free interval and overall survival while neither TIMP-2 nor MMP-2 alone can be used to predict outcome. We suggest that following patients other than those with positive TIMP-2 and negative MMP-2 expression more closely and intensely may improve their prognosis.

PTTG: an important target gene for ovarian cancer therapy

Pituitary tumor transforming gene (PTTG), also known as securin is an important gene involved in many biological functions including inhibition of sister chromatid separation, DNA repair, organ development, and expression and secretion of angiogenic and metastatic factors. Proliferating cancer cells and most tumors express high levels of PTTG. Overexpression of PTTG in vitro induces cellular transformation and development of tumors in nude mice. The PTTG expression levels have been correlated with tumor progression, invasion, and metastasis. Recent studies show that down regulation of PTTG in tumor cell lines and tumors in vivo results in suppression of tumor growth, suggesting its important role in tumorigenesis. In this review, we focus on PTTG structure, sub-cellular distribution, cellular functions, and role in tumor progression with suggestions on possible exploration of this gene for cancer therapy.

TIMP-1 as a tumor marker in breast cancer--an update

Improvement of the management of breast cancer patients has high priority. In this regard, prognostic stratification needs to be improved in order to ensure proper medical treatment of all patients and furthermore predictors of response to chemotherapy are urgently needed. As new treatment opportunities emerge in the future this need will continue to grow. Thus, the search for molecular markers of prognosis and prediction is ongoing. Tissue Inhibitor of Metalloproteinases-1 (TIMP-1) has been suggested as a marker of both prognosis and response to treatment. Several studies have demonstrated the association between TIMP-1 and prognosis in breast cancer and new studies within this area have focused on the possibility of using blood samples or paraffin embedded tissue instead of tumor tissue extracts for measurements of TIMP-1. Interestingly, recent studies have investigated the association between TIMP-1 and response to treatment showing that TIMP-1 may also carry predictive information on response to treatment. In this regard, results from studies of the molecular functions of TIMP-1 point to a role of TIMP-1 in the inhibition of tumor cell apoptosis as an explanation for the clinical findings. This review gives an update on the ongoing investigation of the potential role of TIMP-1 as a tumor marker in breast cancer. Furthermore, we link the clinical findings with studies of the molecular actions of the TIMP-1 protein, raising hypotheses that may explain why TIMP-1 could play an important role in future management of breast cancer patients.

Signaling crossroads: the function of Raf kinase inhibitory protein in cancer, the central nervous system and reproduction

The Raf kinase inhibitory protein 1 (RKIP-1) and its orthologs are conserved throughout evolution and widely expressed in eukaryotic organisms. In its non-phosphorylated form RKIP-1 negatively regulates the Raf/MEK/ERK pathway by interfering with the activity of Raf-1. In its phosphorylated state, RKIP-1 dissociates from Raf-1 and inhibits GRK-2, a negative regulator of G-protein coupled receptors (GPCRs). Available data indicate that the phosphorylation of RKIP-1 by PKC can stimulate both the Raf/MEK/ERK and GPCR pathways. RKIP-1 has also been implicated as a negative regulator of the NF-kappaB pathway. Recent studies have shown that phosphorylated RKIP-1 binds to the centrosomal and kinetochore regions of metaphase chromosomes, where it may be involved in regulating the partitioning of chromosomes and the progression through mitosis. The collective evidence indicates that RKIP-1 regulates the activity and mediates the crosstalk between several important cellular signaling pathways. A variety of ablative interventions suggest that reduced RKIP-1 function may influence metastasis, angiogenesis, resistance to apoptosis, and genome integrity. Attenuation of RKIP-1 may also affect cardiac and neurological functions, spermatogenesis, sperm decapacitation, and reproductive behavior. In this review, the role of RKIP-1 in cellular signaling, and especially its functions revealed using a mouse knockout model, are discussed.

Regulation of angiogenesis and invasion by human Pituitary tumor transforming gene (PTTG) through increased expression and secretion of matrix metalloproteinase-2 (MMP-2)

Background

Pituitary tumor transforming gene (PTTG) is a novel oncogene that is expressed at higher level in most of the tumors analyzed to date compared to normal tissues. Existence of a relationship between PTTG levels and tumor angiogenesis and metastasis has been reported. However, the mechanisms by which PTTG achieve these functions remain unknown. In the present study, we investigated the effect of overexpression of PTTG on secretion and expression of metastasis-related metalloproteinase-2 (MMP-2) in HEK293 cells, cell migration, invasion and tubule formation.

Results

Transient or stable transfection of HEK293 cells with PTTG cDNA showed a significant increase in secretion and expression of MMP-2 measured by zymography, reverse transcriptase (RT/PCR), ELISA, and MMP-2 gene promoter activity. Furthermore, in our studies, we showed that tumor developed in nude mice on injection of HEK293 cells that constitutively express PTTG expressed high levels of both MMP-2 mRNA and protein, and MMP-2 activity. Conditioned medium collected from the HEK293 cells overexpressing PTTG showed a significant increase in cell migration, invasion and tubule formation of human umbilical vein endothelial cells (HUVEC). Pretreatment of conditioned medium with MMP-2-specific antibody significantly decreased these effects, suggesting that PTTG may contribute to tumor angiogenesis and metastasis via activation of proteolysis and increase in invasion through modulation of MMP-2 activity and expression.

Conclusion

Our results provide novel information that PTTG contributes to cell migration, invasion and angiogenesis by induction of MMP-2 secretion and expression. Furthermore, we showed that tumors developed in nude mice on injection of HEK293 cells that constitutively express PTTG induce expression of MMP-2 and significantly increase its functional activity, suggesting a relationship between PTTG levels and MMP-2 which may play a critical role in regulation of tumor growth, angiogenesis and metastasis. Blocking of function of PTTG or down regulation of its expression in tumors may result in suppression of tumor growth and metastasis, through the down regulation of MMP-2 expression and activity. To our knowledge, this study is the first study demonstrating the modulation of MMP-2 expression and biological activity by PTTG.

Regulation of clustered gene expression by cofactor of BRCA1 (COBRA1) in breast cancer cells

Eucaryotic genes that are coordinately expressed tend to be clustered. Furthermore, gene clusters across chromosomal regions are often upregulated in various tumors. However, relatively little is known about how gene clusters are coordinately expressed in physiological or pathological conditions. Cofactor of BRCA1 (COBRA1), a subunit of the human negative elongation factor, has been shown to repress estrogen-stimulated transcription of trefoil factor 1 (TFF1 or pS2) by stalling RNA polymerase II. Here, we carried out a genome-wide study to identify additional physiological target genes of COBRA1 in breast cancer cells. The study identified a total of 134 genes that were either activated or repressed upon small hairpin RNA-mediated reduction of COBRA1. Interestingly, many COBRA1-regulated genes reside as clusters on the chromosomes and have been previously implicated in cancer development. Detailed examination of two such clusters on chromosome 21 (21q22) and chromosome X (Xp11) reveals that COBRA1 is physically associated with a subset of its regulated genes in each cluster. In addition, COBRA1 was shown to regulate both estrogen-dependent and -independent transcription of the gene cluster at 21q22, which encompasses the previously identified COBRA1-regulated TFF1 (pS2) locus. Thus, COBRA1 plays a critical role in the regulation of clustered gene expression at preferred chromosomal domains in breast cancer cells.

Expression of MT-1 MMP, MMP2, MMP9 and TIMP2 mRNAs in ductal carcinoma in situ and invasive ductal carcinoma of the breast

We investigated the expression of membrane type-1 (MT1)-MMP, MMP2, MMP9 and TIMP2 mRNAs and their roles in ductal carcinoma in situ (DCIS) and T1 and T2 invasive ductal carcinoma of the breast. We further compared these two types of carcinomas for differences in microvessel density, and expression of angiogenic factors and CD44std. MT1-MMP, MMP2, MMP9 and TIMP2 mRNA were expressed in both DCIS and invasive ductal carcinomas. Expression rates of MT1-MMP, MMP2, MMP9 and TIMP2 mRNAs were not statistically different between DCIS and invasive ductal carcinomas, nor did they differ statistically when grouped by tumor size, histologic grade or nuclear grade of invasive ductal carcinoma. Microvessel density and expression of VEGF and TGF-beta1 were not statistically different between DCIS and invasive ductal carcinoma. CD44std expression was significantly increased in DCIS compared to invasive ductal carcinoma (p < 0.05) and it was also significantly increased in lower clinical stage, histologic grade and nuclear grade of invasive ductal carcinoma (p < 0.05). Axillary node metastasis was significantly correlated with MT1-MMP mRNA, VEGF and TGF-beta1 expression (p < 0.05) and MT1-MMP mRNA was positively correlated with VEGF expression and TIMP2 mRNA (p < 0.05). In summary, patterns of MMP mRNA expression in DCIS and invasive ductal carcinoma suggest that the invasive potential of breast carcinoma is already achieved before morphologically overt invasive growth is observed. As MT1-MMP mRNA expression is significantly correlated with axillary nodal metastasis, it may be useful as a prognostic indicator of invasive ductal carcinoma. Considering the positive correlation of MT1-MMP mRNA and TIMP2mRNA expression, our finding supports a role for TIMP2 in tumor growth, as well as the utility of CD44std as a prognostic indicator of breast cancer.

The neurotrophin receptor TrkB cooperates with c-Met in enhancing neuroblastoma invasiveness

Neuroblastoma is the most frequent extracranial solid malignancy of childhood with a high mortality in advanced tumour stages. The hallmark of neuroblastoma is its clinical and biological heterogeneity. The molecular mechanisms leading to favourable or unfavourable tumour behaviour are still speculative. However, amplification of the oncogene MYCN and expression of the neurotrophin receptor TrkB are known to contribute to a highly malignant phenotype. To define the mechanisms through which TrkB may mediate neuroblastoma progression, we stably expressed this receptor in the neuroblastoma cell lines SH-SY5Y and SK-N-AS. The transfectants, but not the controls, had an increased invasive potency both, in vitro and in vivo, as demonstrated by Matrigel-invasion and chorioallantoic membrane assays, respectively. The retinoic acid-induced TrkB expression in parental SH-SY5Y cells was also associated with enhanced cell invasiveness. The TrkB mediated invasiveness involved the upregulation of the hepatocyte growth factor (HGF) and its receptor c-Met, resulting in an autocrine loop. Inhibition of HGF activity by anti-HGF neutralizing antibodies or disabling the function of c-Met by small interfering RNA suppressed the TrkB-induced invasiveness. The enhanced TrkB expression was associated with a significant increase in the secretion of various matrix-degrading proteases. Immunostaining and real-time RT-PCR analysis of tumour specimens demonstrated coordinated expression of TrkB and HGF/c-Met in experimental and primary neuroblastomas. We conclude that TrkB expression in neuroblastoma cells results in an increase in their invasive capability via upregulated expression of HGF/c-Met and enhanced activity of proteolytic networks.

Measurement of the Uncomplexed Fraction of Tissue Inhibitor of Metalloproteinases-1 in the Prognostic Evaluation of Primary Breast Cancer Patients*

Several studies have demonstrated an association between high tumor tissue levels of total tissue inhibitor of metalloproteinases-1 (TIMP-1) and a poor prognosis of primary breast cancer patients. In the present study we investigated whether measurements of the uncomplexed fraction of TIMP-1 added prognostic information to that already obtained from total TIMP-1. We measured the uncomplexed fraction of TIMP-1, using a thoroughly validated ELISA specific for this fraction, in 341 tumor tissue extracts obtained from patients with primary breast cancer. These measurements were related to previously performed measurements of total TIMP-1 as well as to patient outcome. The observation time was 8.3 years (range, 7.3-11.3 years). During this period 136 patients died, and 153 patients experienced recurrence of disease. Cox regression analysis of recurrence-free survival (RFS) suggested that a score based on both uncomplexed and total TIMP-1, reflecting the tumor level of TIMP-1/MMP complexes, would be a more precise estimate of prognosis than total TIMP-1 alone. Univariate survival analysis showed a highly significant relationship between high values of the score and poor outcomes for RFS (p = 0.0002; hazard ratio = 2.7; 95% confidence interval, 1.5-4.8). Similar results were found for overall survival (p = 0.0001; hazard ratio = 3.3; 95% confidence interval, 1.8-6.3). Multivariate analysis of RFS and overall survival demonstrated that the score was significant including the classical prognostic factors used in breast cancer (p < 0.0001). The present study raises the hypothesis that it is the tumor level of TIMP-1/MMP complexes (i.e. activated matrix metalloproteinases) rather than TIMP-1 itself that determines prognosis, supporting the use of the combined score and not only total TIMP-1 in stratification of breast cancer patients.

The role of the AP-1 transcription factors c-Fos, FosB, Fra-1 and Fra-2 in the invasion process of mammary carcinomas

Members of the Fos family of AP-1 transcription factors (c-Fos, FosB, FosB2, Fra-1 and Fra-2) are able to form dimers with Jun proteins which bind to the regulatory sequences of target genes. As many proteases involved in tumor invasion are AP-1-regulated, we assumed that Fos family members might be important for invasion of mammary carcinomas. Therefore, we performed transient transfections with expression vectors for c-Fos, FosB, FosB2, Fra-1 and Fra-2, followed by matrigel invasion assays. Fra-1 transfection resulted in a 2-4-fold increase of invasive cells in both cell lines. In a less degree, the invasive potential of MDA-MB231 cells was stimulated by Fra-2, whereas MCF7 invasion was enhanced by c-Fos and FosB. By double-labelling immunocytochemistry, PAI-1 up-regulation was observed in cells transfected with c-Fos, Fra-1 and Fra-2 expression vectors, whereas MMP1 and MMP9 expression was not affected. Results of cotransfection with a MMP9 promoter construct and AP-1 expression vectors do not indicate a direct up-regulation of MMP9 expression by Fos proteins except a positive effect of c-Fos in MCF7 cells. In parallel, expression of Fos family members as determined by Western Blot analysis in 75 mammary carcinomas was correlated with MMP1, MMP9, PAI-1 and uPAR protein levels in the tumors. Interestingly, high FosB levels were significantly associated with MMP1 overexpression, whereas expression of c-Fos and phosphorylated Fra-1 correlated with MMP9 protein levels. Strong Fra-2 expression correlated with high levels of MMP9, PAI-1, the uPA/PAI-1 complex and early recurrence. These data indicate that Fos proteins, especially Fra-1, c-Fos and Fra-2, might be involved in invasion of breast cancer cells.

MMP-2 protein in invasive breast cancer and the impact of MMP-2/TIMP-2 phenotype on overall survival

Crucial event in the metastasis of cancer cells is the secretion of matrix metalloproteinases (MMPs), which are responsible for the degradation of extracellular matrix (ECM). Among them, matrix metalloproteinase-2 (MMP-2) is a gelatinase, which degrades basement membrane type-IV collagen. Immunohistochemistry was performed to detect MMP-2 protein in 135 infiltrative breast carcinomas. MMP-2 was studied along with clinicopathological parameters (tumor size, histological type, nuclear and histological grade, stage, lymph node status, ER, and PR), patients' survival and tissue inhibitor metalloproteinase-2 (TIMP-2), Ki-67, and p53 proteins. MMP-2 immunoreactivity was detected in the cytoplasm in cancer cells in 102 (75.6%) and in both tumor and tumor stromal cells in 37 (27.4%) of 135 cases respectively. MMP-2 reactivity in cancer cells displayed a statistically significant association with tumor size > 2 cm (p = 0.022). In tumor stromal cells a strong parallel association was observed between the expression of MMP-2 and TIMP-2 (p = 0.015), while an inverse correlation was found between MMP-2 and both Ki-67 and p53 (p = 0.033 and p = 0.034 respectively). In the subgroup with negative lymph nodes MMP-2 was also inversely associated with p53 in cancer cells (p = 0.045). Finally a statistically significant association was revealed using Kaplan-Meier and Cox's proportional hazard regression model between the MMP-2/TIMP-2 phenotype and patients' better survival (p = 0.021). Our results point out the strong relation between MMP-2 and TIMP-2 and the effect of the MMP-2/TIMP-2 phenotype in the patients' overall survival. The inverse correlation between MMP-2 and both Ki-67 and p53 can be explained by the potential inhibition of MMP-2 by TIMP-2. These results suggest the necessity of further investigation.

Enhanced mRNA expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) in breast carcinomas is correlated with adverse prognosis

Tissue inhibitor of metalloproteinase-1 (TIMP-1) has emerged as a multifunctional protein with the contrasting activities of inhibiting tissue-degrading enzymes and promoting cellular growth. In an attempt to elucidate the clinical significance of TIMP-1 in breast cancer, the expression of TIMP-1 mRNA was evaluated in 117 invasive breast carcinomas by mRNA in situ hybridization, in correlation with clinicopathological parameters, immunohistochemical prognostic factors (Ki-67, c-erb-B-2, bcl-2) and clinical outcome. TIMP-1 was detected in stromal cells in areas within the tumours and at the tumour margin. High TIMP-1 mRNA expression in the marginal portion of the tumours was significantly correlated with lymph node metastasis (p<0.05) and c-erbB-2 expression (p<0.05). On the other hand, increased TIMP-1 mRNA expression within the tumours showed a statistically significant correlation with ER detection (p<0.01). Multivariate analysis revealed worse survival for patients with high TIMP-1 mRNA expression in the marginal portion of the tumours; the subgroup of these patients co-expressing high levels of TIMP-1 mRNA within the tumours as well had even worse survival (p=0.042). In conclusion, our data support the multifunctional role of TIMP-1, particularly its growth-promoting activity, on the basis of its significant correlation with lymph node metastasis and adverse prognosis. In addition to the latter property, a probable association of TIMP-1 with tumour cell differentiation is suggested by its topographical correlation with ER detection.

Effects of norepinephrine, HIV type 1 infection, and leukocyte interactions with endothelial cells on the expression of matrix metalloproteinases

The expression of matrix metalloproteinases (MMPs) associated with AIDS-related cardiomypathies and cocaine abuse was examined in an in vitro coculture model. Human peripheral blood mononuclear cells (PBMCs), HIV infected or uninfected, were placed in coculture with primary human cardiac microvascular endothelial cells (HMVEC-C) in the presence or absence of the cocaine-inducible catecholamine norepinephrine (NE). Culture supernatants were assayed for MMP-1, -2, -3, -7, -9, and -13, and for tissue inhibitor of metalloproteinase 1 (TIMP-1) and TIMP-2, by enzyme-linked immunosorbent assay. Low levels of constitutively expressed MMP-1 and -2 were detected in individual cultures of HMVEC-C and PBMCs. NE did not induce MMP or TIMP expression by HMVEC-C and caused modest increases (3- to 4-fold) in MMP-1 and -2 by uninfected PBMCs. Increased levels of NE-induced MMP-1 (5-fold) and MMP -2 (15-fold) were detected in cocultures of HMVEC-C and uninfected PBMCs. HIV infection enhanced MMP-1 (46-fold) and MMP-2 (48-fold) and active MMP-7 (33-fold) and MMP-9 (50-fold) by PBMCs. Coculture of HIV-infected PBMCs with HMVEC-C increased MMP-1 (110-fold) and MMP-2 (307-fold) but not active MMP-7 and -9. The combination of NE, HIV infection, and coculture increased MMP-1 (126-fold) and MMP-2 (467-fold), and active MMP-7 (65-fold) and MMP-9 (75-fold). MMP-3 or-13 was not detected in any of the treatment groups and TIMP-1 and -2 appeared inversely proportional to the observed levels of MMPs. These results suggest that HIV infection, NE, and leukocyte endothelial interactions demonstrate separate and overlapping cooperative effects on the regulation of expression of TIMPs and MMPs associated with AIDS-related cardiomyopathies.

Truncated ErbB2 receptor enhances ErbB1 signaling and induces reversible, ERK-independent loss of epithelial morphology

Shedding of the extracellular domain of the ErbB2 tyrosine kinase receptor and expression of the remaining NH(2)-terminally truncated ErbB2 correlates with lymph node metastases and adverse outcome in human breast cancer. To study the possible signaling from such a truncated receptor, MCF-7 human breast cancer cells expressing NH(2)-terminally truncated ErbB2 (DeltaNErbB2) were compared with cells overexpressing wild-type ErbB2. Expression of DeltaNErbB2 in MCF-7 cells resulted in sustained activation of extracellular signal-regulated kinases (ERK) 1/2, extensive loss of the epithelial morphology, appearance of vesicles and long protrusions as well as pronounced scattering of the cells. Similar alterations were observed upon ErbB2 overexpression but at much lower levels. Employing cell clones with inducible expression of DeltaNErbB2, it was revealed that the morphological changes were fully reversible and depended on continuous expression of DeltaNErbB2 but not on the activation of the ERK1/2 pathway. Interestingly, the expression of DeltaNErbB2 resulted also in the increased expression and phosphorylation of ErbB1 as well as in the prolonged ligand-induced activation of the ErbB1 signaling pathway. In conclusion, constitutive signaling upon expression of the truncated ErbB2 receptor in human breast cancer cells promotes morphological changes indicative of a more motile and aggressive phenotype.

Decline in the expression of the serine proteinase inhibitor maspin is associated with tumour progression in ductal carcinomas of the breast

Maspin is an inhibitor of serine proteinases with tumour suppressor activity. Its expression appears to be reduced in advanced stages of breast cancer. A large series of archival breast tissue specimens has been examined, including normal glands (n=7), fibrocystic change (n=22), ductal carcinoma in situ (DCIS, n=12), infiltrating carcinomas (n=128) and their lymph node metastases (n=65), using a specific monoclonal antibody. Myoepithelium invariably showed strong maspin expression. In epithelial cells, the strongest expression was found in normal breast and fibrocystic change. A significant stepwise decrease in maspin expression (p<0.0001) occurred in the sequence DCIS - invasive cancer - lymph node metastasis. However, a subset of infiltrating carcinomas showed strong maspin expression, significantly associated with a lower rate of lymph node metastasis at the time of diagnosis (p<0.01). This was independent of tumour size and grade. The in vivo observations presented here are in keeping with data obtained in prior in vitro experiments. Maspin emerges as an indicator of tumour progression and metastatic potential, and might be exploited to predict breast cancer prognosis. According to in vitro data, its tumour suppressor activity is likely to involve both the modulation of cell motility/invasiveness and the inhibition of angiogenesis.

Genetic basis of human breast cancer metastasis

Once cancer cells have spread and formed secondary masses, breast cancers are largely incurable even with state-of-the-art medicine. To improve diagnosis and therapy, better markers are needed to distinguish cells which have a high probability for causing clinically relevant, macroscopic metastases. In this review, we summarize the several genes that regulate breast cancer metastasis. Two categories of genes are presented--metastasis activator (ras, MEK1, mta1, proteinases, adhesion molecules, chemoattractants/receptors, autotaxin, PKC, S100A4, RhoC, osteopontin) and metastasis suppressor (Nm23, E-cadherin, TIMPs, KiSS1, Kai1, Maspin, MKK4, BRMS1). While the mechanisms of action for most of these genes are not fully elucidated, some clues are emerging and are presented.

Quantification of matrix metalloproteinase activity in plasma of patients enrolled in a BAY 12-9566 phase I study

The expression of matrix metalloproteinases (MMPs) is often associated with invasiveness or grade of tumours. Increased blood levels of MMP proteins, including MMP-1, MMP-2, MMP-3 and MMP-9 have been detected in various types of cancers. With the exception of one study, MMPs in serum and plasma have been determined using ELISA. In the present study we measured the activity of the MMPs found in human plasma samples using gelatin enzymography and fluorimetric degradation assays. We used plasma samples from healthy control subjects and cancer patients enrolled in a dose-finding study for the MMP inhibitor, BAY 12-9566, to assess the activity of MMPs found in plasma and screen for efficacy of the MMP inhibitor. BAY 12-9566 has inhibitory activity toward MMP-2, MMP-3 and MMP-9. Patients with advanced solid tumours were enrolled in our study and plasma was collected on day 1 before dosing and at steady-state of the drug on day 15. Our results show that BAY 12-9566 was effective in lowering the plasma gelatinolytic activity in the group of 29 patients when considering the data obtained from a fluorimetric gelatinase assay. The data obtained from gelatin enzymography, however, did not reach significance. The fluorimetric degradation assay could be a useful tool to screen plasma from cancer patients in other clinical trials assessing MMP inhibitors.

Design, synthesis, and evaluation of a pyrrolinone-based matrix metalloprotease inhibitor

[reaction: see text] A pyrrolinone-based hydroxamate matrix metalloprotease inhibitor, (-)-1, has been designed and synthesized. Enzymatic assay revealed that (-)-1 inhibited three of the ten matrix metalloprotease enzymes examined and as such represents a new, potentially important lead structure.

Paradoxical pro-invasive effect of the serine proteinase inhibitor tissue factor pathway inhibitor-2 on human hepatocellular carcinoma cells

We have previously shown that human liver myofibroblasts promote in vitro invasion of human hepatocellular carcinoma (HCC) cells through a hepatocyte growth factor (HGF)/urokinase/plasmin-dependent mechanism. In this study, we demonstrate that myofibroblasts synthesize the serine proteinase inhibitor tissue factor pathway inhibitor-2 (TFPI-2). Despite the fact that recombinant TFPI-2 readily inhibits plasmin, we show that it potentiates HGF-induced invasion of HCC cells and is capable of inducing invasion on its own. Furthermore, HCC cells stably transfected with a TFPI-2 expression vector became spontaneously invasive. HCC cells express tissue factor and specifically factor VII. Addition of an antibody to factor VII abolished the pro-invasive effect of TFPI-2. We suggest that TFPI-2 induces invasion following binding to a tissue factor-factor VIIa complex preformed on HCC cells. Our data thus demonstrate an original mechanism of cell invasion that may be specific for liver tumor cells.

Biological mechanisms in breast cancer invasiveness: relevance to preventive interventions

Migration studies suggest that the high incidence of postmenopausal breast cancer in Western women is related mainly to epigenetic factors. Progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) also appears to involve environmental rather than genetic factors, and a role has been postulated for metabolic-endocrine changes related to the Western lifestyle. Protein kinase C (PKC) is important in cell signal transduction, and laboratory studies show that PKC stimulates the activities of urokinase plasminogen activator, matrix metalloproteinases and cell adhesion molecules, all of which are known to increase invasiveness in human mammary cancer cell lines. In rodents, the activity of PKC in tissue cells is enhanced by insulin, and PKC isoenzymes have been shown to stimulate the development of hyperinsulinaemic insulin resistance in rodents. Clinically, hyperinsulinaemia and the concomitant increase in circulating levels of free oestradiol and bioactive insulin-like growth factor 1 (IGF1) are each confirmed markers of high risk for breast cancer in women. Lesions of DCIS show evidence of regression with mammary involution, but it is postulated that this may be opposed by the concomitants of hyperinsulinaemic insulin resistance. The prevalence of the latter is increasing in Western populations, and a combination of high IGF1 and low IGF-binding protein 3 concentrations has been associated with the presence of DCIS lesions in premenopausal women. Measures that enhance insulin sensitivity in such women may reduce the risk of progression in DCIS lesions, and a clinical trial is proposed to test the hypothesis.