pS2 and response to adjuvant hormone therapy in primary breast cancer

Impact of Steroid Receptors, pS2 and Cathepsin D on the Outcome of N+ Postmenopausal Breast Cancer Patients Treated with Tamoxifen

In spite of the complexity of the biological basis of the hormonal regulation of breast cancer, clinical studies tend to simplify the information by mainly categorizing continuous variables related to hormonal status and not considering the interactions between variables. The present study was planned to examine the presence of an interaction between cathepsin D (Cath-D) and pS2 in patients treated with adjuvant tamoxifen in a homogeneous subset of node-positive postmenopausal patients and to evaluate the contribution of the interaction to the predictive ability of the model. Steroid receptors (ER and PgR) were measured in cytosol using the dextran-coated charcoal method, while Cath-D and pS2 were determined using commercially available immunoradiometric assays. The prognostic role of each variable and their joint effect were investigated using a Cox regression model. Biological variables were analyzed as continuous and when their prognostic relationship did not seem linear, a restricted cubic spline regression smoothing approach was adopted. The logarithm of hazard showed a linear relationship with the log(ER), while it i) remained almost constant up to about 20 fmol/mg and subsequently decreased for PgR; ii) was almost constant up to about 50 pmol/mg and subsequently decreased for Cath-D; iii) decreased for increasing log(value) up to about 33 ng/mg and subsquently increased for pS2. In the multivariate analysis both PgR and the interaction between pS2 and Cath-D retained a significant prognostic role. For low values of pS2, the prognosis worsened with the increase in Cath-D levels and this relationship reversed for high values of pS2. From the results of the present study we can conclude that i) a significant interaction between Cath-D and pS2 was found in this case series; ii) the prognostic relationships should not be underestimated in clinical decision making; iii) a predictive score obtained considering the contribution of PgR, pS2 and Cath-D could be useful for clinical use.

Cytosolic Levels of An Estrogen-Induced Breast Cancer-Associated Peptide (TFF1/pS2) in Colorectal Cancer: Clinical Significance and Relationship with Steroid Receptors

Background

The Trefoil Factor 1 (TFF1/pS2), a peptide consisting of 60 amino acids, is the most abundant estrogen-induced messenger RNA in MCF-7 breast cancer cells and is also expressed by colorectal carcinomas. The objective of this work was to evaluate the cytosolic TFF1 content in colorectal carcinomas, its possible relationship with estrogen and progesterone receptors as well as with clinicopathological tumor parameters, and its potential prognostic significance.

Methods

Cytosolic TFF1 levels were examined by immunoradiometric assay in 178 patients with resectable colorectal cancer. The mean follow-up period was 32 months.

Results

There was a wide variability of cytosolic TFF1 levels in tumor-surrounding mucosa samples (0.09-42.5 ng/mg protein) as well as in tumors (0.01-270 ng/mg protein). Comparison of paired mucosa and carcinoma samples showed significantly higher TFF1 levels in tumors (mean: 17.1 ng/mg protein) than in mucosa samples (10 ng/mg protein) (p=0.027). TFF1 levels were significantly higher in mucosa samples surrounding distal colon and rectal tumors (p=0.0001) and in tumor samples obtained from older patients (p=0.007). However, there were no significant differences in tumor TFF1 levels with respect to clinicopathological parameters such as the patient's sex, tumor location, stage, histological grade, ploidy, S-phase, or tumor estrogen and progesterone receptors. In addition, there was no significant relationship between tumor TFF1 levels and disease outcome.

Conclusions

TFF1 may play an as yet undetermined role in the tumorigenesis of colorectal carcinomas. However, cytosolic levels of TFF1 do not seem to have any prognostic significance in colorectal carcinomas.

Endocrine therapy resistance in estrogen receptor (ER)-positive breast cancer

Estrogen receptor (ER)-positive breast cancer represents the majority (∼70%) of all breast malignancies. In this subgroup of breast cancers, endocrine therapies are effective both in the adjuvant and recurrent settings, although resistance remains a major issue. Several high-throughput approaches have been used to elucidate mechanisms of resistance and to derive potential predictive markers or alternative therapies. In this review, we cover the state-of-the-art of endocrine-resistance biomarker discovery with regard to the latest technological developments, and discuss current opportunities and restrictions for their implementation into a clinical setting.

TFF3 is a valuable predictive biomarker of endocrine response in metastatic breast cancer

The stratification of breast cancer patients for endocrine therapies by oestrogen or progesterone receptor expression is effective but imperfect. The present study aims were to validate microarray studies that demonstrate TFF3 regulation by oestrogen and its association with oestrogen receptors in breast cancer, to evaluate TFF3 as a biomarker of endocrine response, and to investigate TFF3 function. Microarray data were validated by quantitative RT-PCR and northern and western transfer analyses. TFF3 was induced by oestrogen, and its induction was inhibited by antioestrogens, tamoxifen, 4-hydroxytamoxifen and fulvestrant in oestrogen-responsive breast cancer cells. The expression of TFF3 mRNA was associated with oestrogen receptor mRNA in breast tumours (Pearson's coefficient=0.762, P=0.000). Monoclonal antibodies raised against the TFF3 protein detected TFF3 by immunohistochemistry in oesophageal submucosal glands, intestinal goblet and neuroendocrine cells, Barrett's metaplasia and intestinal metaplasia. TFF3 protein expression was associated with oestrogen receptor, progesterone receptor and TFF1 expression in malignant breast cells. TFF3 is a specific and sensitive predictive biomarker of response to endocrine therapy, degree of response and duration of response in unstratified metastatic breast cancer patients (P=0.000, P=0.002 and P=0.002 respectively). Multivariate binary logistic regression analysis demonstrated that TFF3 is an independent biomarker of endocrine response and degree of response, and this was confirmed in a validation cohort. TFF3 stimulated migration and invasion of breast cancer cells. In conclusion, TFF3 expression is associated with response to endocrine therapy, and outperforms oestrogen receptor, progesterone receptor and TFF1 as an independent biomarker, possibly because it mediates the malign effects of oestrogen on invasion and metastasis.

Trefoil factor 1 in early breast carcinoma: a potential indicator of clinical outcome during the first 3 years of follow-up

BACKGROUND

A role of an estrogen-regulated, autocrine motogenic factor was assumed to be a major biological role of trefoil factor 1 (TFF1) in breast cancer. TFF1 is regarded as a predictive factor for positive response to endocrine therapy in breast cancer patients. The aim of our study was to examine TFF1 level distribution in breast carcinomas in order to distinguish estrogen-independent from estrogen-dependent TFF1 expression and to evaluate clinical usefulness of TFF1 status in early breast cancer during the first 3 years of follow-up.

METHODS

The study included 226 patients with primary operable invasive early breast carcinomas for whom an equal, a 3-year follow-up was conducted. TFF1 levels as well as estrogen receptor (ER) and progesterone receptor (PR) levels were measured in cytosolic extracts of tumor samples by immunoradiometric assay or by use of classical biochemical method, respectively. Non-parametric statistical tests were applied for data analyses.

RESULTS

Statistical analysis revealed that TFF1 levels were significantly higher in premenopausal patients (p=0.02), or in tumors with: lower histological grade (p<0.001), positive ER or PR status (p<0.001, in both cases). On the basis of TFF1 level distribution between ER-negative and ER-positive postmenopausal patients with tumors of different histological grade, 14 ng/mg was set as the cut-off value to distinguish estrogen-independent from estrogen-dependent TFF1 expression in breast cancer. Depending on menopausal and PR status, positive TFF1 status identified patients at opposite risk for relapse among ER-positive patients with grade II tumors. Among ER- and PR-positive premenopausal patients with grade II tumors, TFF1 status alone identified patients at opposite risk for relapse.

CONCLUSIONS

Determination of TFF1 status might identify patients at different risk for relapse and help in making decision on administering adjuvant therapy for early breast cancer patients during the first 3 years of follow-up.

[Circulating proteinic biomarkers and breast cancer]

Circulating proteinic biomarkers are secreted by tumor cells or by their environmental cells and they have a variable specificity. In case of breast cancer, carcino-embryonic antigen (CEA) was for a long time the only circulating biomarker used. Nowadays, the most useful biomarkers measure circulating levels of fragments of MUC1-polymorphic epithelial mucin (MUC1-PEM): cancer antigen (CA) 15.3, mucin-like carcinoma-associated antigen (MCA), CA 27-29, CA 549... They are useful for general disease follow-up. Other circulating markers belonging to keratins (tissue polypeptide antigen, TPA, TPS or Cyfra 21.1) are correlated with proliferative activity of breast tumors. More recently, the measure of the c-erb B2 circulating part (extra cellular domain, ECD) was proposed as a prognostic biomarker for breast tumors with c-erb B2 overexpression. Moreover, the determination of urinary level of trefoil factor1 (PS2-TFF1) might be useful for the follow-up of hormonodependent breast cancers. The present review describes the clinical interest of these different circulating biomarkers in case of breast cancer, emphasizing their biological characteristics.

Cytosolic levels of TFF1/pS2 in breast cancer: Their relationship with clinical-pathological parameters and their prognostic significance

BACKGROUND

The Trefoil Factor 1 (TFF1/pS2), a peptide consisting of 60 amino acids, is the most abundant estrogen-induced messenger RNA present in MCF-7 breast cancer cells. The objective of this work was to evaluate the cytosolic TFF1 content in breast carcinomas, its possible relationship with different clinical-pathological parameters, and its potential prognostic significance and predictive value.

METHODS

Cytosolic TFF1 levels were examined by immunoradiometric assay in 1031 patients with invasive breast cancer. The median follow-up period was of 50 months.

RESULTS

There was a wide variability of cytosolic TFF1 levels in tumors (0.9-743.2 ng/mg protein). Statistical analysis showed that TFF1 levels were significantly higher in premenopausal patients (p = 0.001), as well as in tumors showing any of the following characteristics: good differentiation (p = 0.0001), ER and PgR positivity (p = 0.0001 and p = 0.001, respectively), diploidy (p = 0.045) and a high S-phase fraction (p = 0.001). In addition, the presence of high intratumoral TFF1 levels (cut-off: 2 ng/mg protein) was independently associated with a shorter overall survival in the group of patients as a whole (p = 0.001) as well as in the subgroup with node-negative breast cancer (p = 0.0004). Likewise, high intratumoral TFF1 levels were associated with a more prolonged overall survival in patients who received adjuvant tamoxifen (p = 0.004).

CONCLUSIONS

In breast cancer patients, intratumoral TFF1 levels are associated with a better clinical outcome, especially in those with node-negative tumors. In addition, TFF1 levels have a low but significant predictive value in regards to response to adjuvant therapy with tamoxifen.

Predictive Markers in Breast and Other Cancers: A Review

Background: Unpredictable efficacy and toxicity are hallmarks of most anticancer therapies. Predictive markers are factors that are associated with response or resistance to a particular therapy.

Methods: The English literature relating to predictive markers in oncology was reviewed. Particular attention was paid to metaanalyses, systematic reviews, prospective trials, and guidelines issued by expert panels.

Results: The prototype predictive tests in oncology are the estrogen receptor (ER) and progesterone receptor (PR), which are used to select patients with breast cancer likely to respond to hormone therapy. A more recently introduced predictive marker is HER-2 for selecting patients with advanced breast cancer for treatment with the therapeutic antibody trastuzumab (Herceptin). In adjuvant breast cancer, overproduction of HER-2 may also indicate an enhanced sensitivity to high-dose anthracycline-based regimens. On the other hand, in both early and advanced breast cancer, high concentrations of HER-2 appear to correlate with a lower probability of response to hormone therapy. Although many different anticancer drugs appear to mediate tumor regression by inducing apoptosis, there is currently no consistent evidence that any of the molecules implicated in this process can be used as predictive markers.

Conclusions: Currently, the only recommended predictive markers in oncology are ER and PR for selecting endocrine-sensitive breast cancers and HER-2 for identifying breast cancer patients with metastatic disease who may benefit from trastuzumab. For malignancies other than breast cancers, validated predictive markers do not exist at present.

mRNA expression level of estrogen-inducible gene, alpha 1-antichymotrypsin, is a predictor of early tumor recurrence in patients with invasive breast cancers

We previously identified 18 genes that correlated with ER positivity by adapter-tagged competitive-PCR analysis of 2412 genes in human breast cancer tissues. The aim of the present study was to determine the prognostic significance of these genes. mRNA expression levels of 12 of the above 18 genes were quantified in breast cancer tissues by real-time PCR assay, and their association with patients' prognosis (n = 110) was studied according to hormone receptor (HR) status. In addition, the genes found to influence prognosis were further investigated to examine whether their mRNA expression could be induced by estrogen in MCF-7 cells in vitro. Of the 12 genes, mRNA expression levels of two [alpha 1-antichymotrypsin (ACT) and stanniocalcin 2 (STC2)] were significantly (P = 0.002 and P = 0.007, respectively) associated with good prognosis in HR-positive (ER and/or PR positive) breast cancer patients treated with adjuvant hormone therapy. Multivariate analysis showed that ACT mRNA level, but not STC2 mRNA level, in HR-positive patients, was a significant prognostic factor (P = 0.042), which was independent of tumor size and lymph node metastases. On the other hand, mRNA expressions of ACT and STC2 were not significantly associated with prognosis in HR-negative patients. Estradiol treatment resulted in a significant increase in the mRNA levels of both ACT and STC2 in MCF-7 cells. The mRNA level of ACT, which is an estrogen-inducible gene, is a significant predictor of good prognosis in HR-positive, but not HR-negative, patients with breast cancers. Since HR-positive patients were treated with adjuvant hormone therapy, we suggest that ACT mRNA level could potentially be used as a predictor of response to hormone therapy, rather than a prognostic factor (predictor of metastatic potential).

Human ADA3 binds to estrogen receptor (ER) and functions as a coactivator for ER-mediated transactivation

We have recently identified the hADA3 protein, the human homologue of yeast transcriptional coactivator yADA3, as a novel HPV16 E6 target. Using ectopic expression approaches, we further demonstrated that hADA3 directly binds to the 9-cis retinoic acid receptors alpha and beta, and functions as a coactivator for retinoid receptor-mediated transcriptional activation. Here, we examined the role of endogenous hADA3 as a coactivator for estrogen receptor (ER), an important member of the nuclear hormone receptor superfamily. We show that ADA3 directly interacts with ER alpha and ER beta. Using the chromatin immunoprecipitation assay, we also show that hADA3 is a component of the activator complexes bound to the native ER response element within the promoter of the estrogen-responsive gene pS2. Furthermore, using an ER response element-luciferase reporter, we show that overexpression of ADA3 enhances the ER alpha- and ER beta-mediated sequence-specific transactivation. Reverse transcription-PCR analysis showed an ADA3-mediated increase in estrogen-induced expression of the endogenous pS2 gene. More importantly, using RNA interference against hADA3, we demonstrate that inhibition of endogenous hADA3 inhibited ER-mediated transactivation and the estrogen-induced increase in the expression of pS2, cathepsin D, and progesterone receptor, three widely known ER-responsive genes. The HPV E6 protein, by targeting hADA3 for degradation, inhibited the ER alpha-mediated transactivation and the protein expression of ER target genes. Thus, our results demonstrate that ADA3 directly binds to human estrogen receptor and enhances the transcription of ER-responsive genes, suggesting a broader role of mammalian hADA3 as a coactivator of nuclear hormone receptors and the potential role of these pathways in HPV oncogenesis.

Urinary pS2/TFF1 levels in the management of hormonodependent breast carcinomas

pS2/TFF1 overexpression in breast carcinomas correlates with response to hormonotherapy. We evaluated the clinical relevance of urinary pS2/TFF1 in breast cancer patients. In healthy controls (100 cases), it represents an individual and relatively stable parameter. Although 24 out 83 pre-operative breast cancer patients showed elevated levels, both the sensitivity and specificity of the test were too low for breast cancer screening. However, neoadjuvant hormonotherapy decreased pS2/TFF1 levels in nine out of 20 patients. Furthermore, among 22 patients receiving long-term adjuvant hormonotherapy, four exhibited elevated levels, two of them at the time of relapse. Thus, urinary pS2/TFF1 quantification might be suitable as an in vivo diagnosis for tumor hormonodependency, and disease follow-up during hormonotherapy.

Thymine-rich single-stranded DNA activates Mcm4/6/7 helicase on Y-fork and bubble-like substrates

The presence of multiple clusters of runs of asymmetric adenine or thymine is a feature commonly found in eukaryotic replication origins. Here we report that the helicase and ATPase activities of the mammalian Mcm4/6/7 complex are activated specifically by thymine stretches. The Mcm helicase is specifically activated by a synthetic bubble structure which mimics an activated replication origin, as well as by a Y-fork structure, provided that a single-stranded DNA region of sufficient length is present in the unwound segment or 3' tail, respectively, and that it carries clusters of thymines. Sequences derived from the human lamin B2 origin can serve as a potent activator for the Mcm helicase, and substitution of its thymine clusters with guanine leads to loss of this activation. At the fork, Mcm displays marked processivity, expected for a replicative helicase. These findings lead us to propose that selective activation by stretches of thymine sequences of a fraction of Mcm helicases loaded onto chromatin may be the determinant for selection of initiation sites on mammalian genomes.

Overexpression of intestinal trefoil factor in human colon carcinoma cells reduces cellular growth in vitro and in vivo

BACKGROUND & AIMS

Intestinal trefoil factor (ITF) has a role in gastrointestinal mucosal integrity and the repair of damaged mucosa. However, little is known about its role in tumors. To analyze the role of ITF in colon carcinomas, overexpression of the ITF gene in colon carcinoma cells was used.

METHODS

Human colon carcinoma cell lines LoVo and SW837, expressing no endogenous ITF, and WiDr expressing a low level of ITF were stably transfected with an expression vector harboring human ITF complementary DNA. The effects of ITF overexpression on in vitro growth, morphology in collagen gel, response to epidermal growth factor (EGF), mitogen-activated protein kinase (MAPK) activity, and growth in nude mice were assessed.

RESULTS

Overexpression of ITF in LoVo and SW837 resulted in significantly reduced growth in vitro and in vivo. In collagen gels, the ITF-expressing LoVo clones formed smaller, more dispersed colonies. EGF-induced phosphorylation of MAPKs was modestly reduced in the ITF-expressing clones. The growth of WiDr was modestly suppressed only in vivo by ITF overexpression.

CONCLUSIONS

Overexpression of ITF suppressed the growth of colon carcinoma cells. ITF may function as an inhibitory factor for the growth of colonic neoplasm.

pS2/TFF1 interacts directly with the VWFC cysteine-rich domains of mucins

BACKGROUND & AIMS

Trefoil factors (TFFs) are secreted gastrointestinal proteins that have been shown to protect and promote healing of the gastrointestinal tract. Moreover, pS2/TFF1 is essential for normal differentiation of the gastric mucosa because deficient mice develop antropyloric adenomas. To date, it is unclear how TFFs mediate their functions.

METHODS

Using the yeast 2-hybrid system, we attempted to identify murine TFF1 interacting proteins by screening a stomach and duodenum complementary DNA (cDNA) expression library.

RESULTS

Four positive clones were isolated. Sequence and expression studies showed that they corresponded to the murine counterpart of human cDNA sequences encoding carboxy-terminal fragments of mMuc2 (489 residues) and mMuc5AC (427, 430, and 894 residues) mucin proteins. Mutagenesis experiments showed that TFF1 interacts with the 2 mucins through binding with their VWFC1 and VWFC2 (von Willebrand factor C) cysteine-rich domains.

CONCLUSIONS

These results show that the gastrointestinal protective effect of TFF1, and presumably of the other TFFs, is caused at least partially by their participation, via mucin binding, in the correct organization of the mucous layer that protects the apical side of the mucosa from deleterious luminal agents.

Time at surgery during menstrual cycle and menopause affects pS2 but not cathepsin D levels in breast cancer

Many studies have addressed the clinical value of pS2 as a marker of hormone responsiveness and of cathepsin D (Cath D) as a prognostic factor in breast cancer. Because pS2 and Cath D are both oestrogen induced in human breast cancer cell lines, we studied the influence of the menstrual cycle phase and menopausal status at the time of surgery on the levels of these proteins in breast cancer. A population of 1750 patients with breast cancer, including 339 women in menstrual cycle, was analysed. Tumoral Cath D and pS2 were measured by radioimmunoassay. Serum oestradiol (E2), progesterone (Pg), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels at the day of surgery were used to define the hormonal phase in premenopausal women. There was a trend towards a higher mean pS2 level in the follicular phase compared with the luteal phase (17 ng mg(-1) and 11 ng mg(-1) respectively, P = 0.09). Mean pS2 was lower in menopausal patients than in women with cycle (8 ng mg(-1) and 14 ng mg(-1) respectively, P = 0.0001). No differences in mean Cath D level were observed between the different phases of the menstrual cycle, or between pre- and post-menopausal women. In the overall population, pS2 was slightly positively associated with E2 and Pg levels and negatively associated with FSH and LH, probably reflecting the link between pS2 and menopausal status. In premenopausal women, no association was found between pS2 and E2, Pg, FSH or LH levels. There were no correlations between Cath D level and circulating hormone levels in the overall population. However, in the subgroup of premenopausal women with ER-positive (ER+) tumours, E2 was slightly associated with both pS2 and Cath D, consistent with oestrogen induction of these proteins in ER+ breast cancer cell lines. There are changes in pS2 level in breast cancer throughout the menstrual cycle and menopause. This suggests that the choice of the pS2 cut-off level should take the hormonal status at the time of surgery into account. In contrast, the level of Cath D is unrelated to the menstrual cycle and menopausal status.

Identification of BCAR3 by a random search for genes involved in antiestrogen resistance of human breast cancer cells

The antiestrogen tamoxifen is important in the treatment of hormone-dependent breast cancer, although development of resistance is inevitable. To unravel the molecular mechanisms of antiestrogen resistance, a search for involved genes was initiated. Retrovirus-mediated insertional mutagenesis was applied to human ZR-75-1 breast cancer cells. Infected cells were subjected to tamoxifen selection and a panel of resistant cell clones was established. Screening for a common integration site resulted in the identification of a novel gene designated BCAR3. Transfer of this locus by cell fusion or transfection of the BCAR3 cDNA to ZR75-1 and MCF-7 cells induces antiestrogen resistance. BCAR3 represents a putative SH2 domain-containing protein and is partly homologous to the cell division cycle protein CDC48.

The estrogen responsive element of the pS2 gene is recognized by a methylation sensitive DNA binding protein

The human pS2 gene is specifically expressed is a subclass of estrogen receptor containing human breast cancer cells. In the MCF7 cell line, its induction by estradiol is a primary transcriptional event. The exact location of its estrogen responsive element has been determined using a chimeric recombinant transfected into HeLa cells and a transient expression assay. In this study we found, using electrophoretic mobility shift experiments, that in HeLa cells the estrogen responsive element (ERE) of the pS2 gene is recognized by a methylation sensitive DNA binding protein (MSDBP) different from the estrogen receptor. Competition experiments have shown that the binding of this protein requires at least one CpG in the center of the palindromic sequence and that imperfect palindromic sequences are also recognized. Although the presence of CpG is necessary, CpG-rich oligonucleotides, containing consensus sequences for Sp1 or AP2, do not interfere with its binding to the pS2 oligonucleotide, indicating that the ERE sequence itself participates in the specificity of its binding. This protein binds the pS2 sequence with a relatively high affinity (apparent Kd = 10(-10) M) and its binding is strongly reduced by the methylation of the cytosines at CpG sites. UV cross-linking experiments and peptide mapping indicate that this protein has an apparent molecular weight of 46 kDa and is present in several cell lines, including non-human cell lines. Taken together, these data suggest that this protein might have a potential role in regulating gene activity or in chromatin structure of some genes possessing an ERE.