Detection of bone marrow-disseminated breast cancer cells using an RT-PCR assay of MUC5B mRNA

The mutational landscape of a US Midwestern breast cancer cohort reveals subtype-specific cancer drivers and prognostic markers

BACKGROUND

Female breast cancer remains the second leading cause of cancer-related death in the USA. The heterogeneity in the tumor morphology across the cohort and within patients can lead to unpredictable therapy resistance, metastasis, and clinical outcome. Hence, supplementing classic pathological markers with intrinsic tumor molecular markers can help identify novel molecular subtypes and the discovery of actionable biomarkers.

METHODS

We conducted a large multi-institutional genomic analysis of paired normal and tumor samples from breast cancer patients to profile the complex genomic architecture of breast tumors. Long-term patient follow-up, therapeutic regimens, and treatment response for this cohort are documented using the Breast Cancer Collaborative Registry. The majority of the patients in this study were at tumor stage 1 (51.4%) and stage 2 (36.3%) at the time of diagnosis. Whole-exome sequencing data from 554 patients were used for mutational profiling and identifying cancer drivers.

RESULTS

We identified 54 tumors having at least 1000 mutations and 185 tumors with less than 100 mutations. Tumor mutational burden varied across the classified subtypes, and the top ten mutated genes include MUC4, MUC16, PIK3CA, TTN, TP53, NBPF10, NBPF1, CDC27, AHNAK2, and MUC2. Patients were classified based on seven biological and tumor-specific parameters, including grade, stage, hormone receptor status, histological subtype, Ki67 expression, lymph node status, race, and mutational profiles compared across different subtypes. Mutual exclusion of mutations in PIK3CA and TP53 was pronounced across different tumor grades. Cancer drivers specific to each subtype include TP53, PIK3CA, CDC27, CDH1, STK39, CBFB, MAP3K1, and GATA3, and mutations associated with patient survival were identified in our cohort.

CONCLUSIONS

This extensive study has revealed tumor burden, driver genes, co-occurrence, mutual exclusivity, and survival effects of mutations on a US Midwestern breast cancer cohort, paving the way for developing personalized therapeutic strategies.

Mucins as contrast agent targets for fluorescence-guided surgery of pancreatic cancer

Pancreatic cancer is difficult to resect due to its unique challenges, often leading to incomplete tumor resections. Fluorescence-guided surgery (FGS), also known as intraoperative molecular imaging and optical surgical navigation, is an intraoperative tool that can aid surgeons in complete tumor resection through an increased ability to detect the tumor. To target the tumor, FGS contrast agents rely on biomarkers aberrantly expressed in malignant tissue compared to normal tissue. These biomarkers allow clinicians to identify the tumor and its stage before surgical resection and provide a contrast agent target for intraoperative imaging. Mucins, a family of glycoproteins, are upregulated in malignant tissue compared to normal tissue. Therefore, these proteins may serve as biomarkers for surgical resection. Intraoperative imaging of mucin expression in pancreatic cancer can potentially increase the number of complete resections. While some mucins have been studied for FGS, the potential ability to function as a biomarker target extends to the entire mucin family. Therefore, mucins are attractive proteins to investigate more broadly as FGS biomarkers. This review summarizes the biomarker traits of mucins and their potential use in FGS for pancreatic cancer.

Toll like receptors TLR1/2, TLR6 and MUC5B as binding interaction partners with cytostatic proline rich polypeptide 1 in human chondrosarcoma

Metastatic chondrosarcoma is a bone malignancy not responsive to conventional therapies; new approaches and therapies are urgently needed. We have previously reported that mTORC1 inhibitor, antitumorigenic cytostatic proline rich polypeptide 1 (PRP-1), galarmin caused a significant upregulation of tumor suppressors including TET1/2 and SOCS3 (known to be involved in inflammatory processes), downregulation of oncoproteins and embryonic stem cell marker miR-302C and its targets Nanog, c-Myc and Bmi-1 in human chondrosarcoma. To understand better the mechanism of PRP-1 action it was very important to identify the receptor it binds to. Nuclear pathway receptor and GPCR assays indicated that PRP-1 receptors are not G protein coupled, neither do they belong to family of nuclear or orphan receptors. In the present study, we have demonstrated that PRP-1 binding interacting partners belong to innate immunity pattern recognition toll like receptors TLR1/2 and TLR6 and gel forming secreted mucin MUC5B. MUC5B was identified as PRP-1 receptor in human chondrosarcoma JJ012 cell line using Ligand-receptor capture technology. Toll like receptors TLR1/2 and TLR6 were identified as binding interaction partners with PRP-1 by western blot analysis in human chondrosarcoma JJ012 cell line lysates. Immunocytochemistry experiments confirmed the finding and indicated the localization of PRP-1 receptors in the tumor nucleus predominantly. TLR1/2, TLR6 and MUC5B were downregulated in human chondrosarcoma and upregulated in dose-response manner upon PRP-1 treatment. Experimental data indicated that in this cellular context the mentioned receptors had tumor suppressive function.

MUC5B silencing reduces chemo-resistance of MCF-7 breast tumor cells and impairs maturation of dendritic cells

Mucins participate in cancer progression by regulating cell growth, adhesion, signaling, apoptosis or chemo-resistance to drugs. The secreted mucin MUC5B, the major component of the respiratory tract mucus, is aberrantly expressed in breast cancer, where it could constitute a cancer biomarker. In this study we evaluated the role of MUC5B in breast cancer by gene silencing the MUC5B expression with short hairpin RNA on MCF-7 cells. We found that MUC5B-silenced MCF-7 cells have a reduced capacity to grow, adhere and form cell colonies. Interestingly, MUC5B knock-down increased the sensitivity to death induced by chemotherapeutic drugs. We also show that MUC5B silencing impaired LPS-maturation of DCs, and production of cytokines. Furthermore, MUC5B knock-down also influenced DC-differentiation and activation since it resulted in an upregulation of IL-1β, IL-6 and IL-10, cytokines that might be involved in cancer progression. Thus, MUC5B could enhance the production of LPS-induced cytokines, suggesting that the use of MUC5B-based cancer vaccines combined with DC-maturation stimuli, could favor the induction of an antitumor immune response.

A recyclable chitosan-based QCM biosensor for sensitive and selective detection of breast cancer cells in real time

A highly sensitive and recyclable quartz crystal microbalance (QCM) biosensor was developed using chitosan (CS) and folic acid (FA), generating conjugates that are selectively recognized by MCF-7 cancer cell over-expressed folic acid receptors. The prepared CS-FA conjugate was characterized by UV-vis spectroscopy and Fourier transform infrared spectroscopy. Atomic force microscopy and scanning electron microscopy further presented the morphology of the CS-FA conjugate interface. The hydrophilicity of films was characterized by measuring the contact angle. The recognition of MCF-7 cancer cells was investigated in situ using QCM. Captured by FA, the concentration of the MCF-7 cell was determined on-line using a quartz crystal microbalance and a wide linear range of 4.5 × 10(2) to 1.01 × 10(5) cells per mL was obtained, with a detection limit of 430 cells per mL. The fluorescence microscope further confirmed the specificity and biocompatibility of the constructed biosensor. In addition, the regeneration of the QCM biosensor was studied by using lysozyme. This receptor-bound ligand based QCM biosensor also showed good selectivity, and repeatability in the cell mixture. For the first time, this simple, economical and label-free chitosan-based QCM sensing was demonstrated, and such design could provide a promising detection strategy for sensitive detection of cancer cell over-expressed folic acid receptors.

Mucins and Cytokeratins as Serum Tumor Markers in Breast Cancer

Structural and functional characteristics of mucins and cytokeratins are shortly described. Thereafter, those commonly used in breast cancer as serum tumor markers are considered. First CA15.3, MCA, CA549, CA27.29 mucins and CYFRA21.1, TPA, TPS cytokeratins alone or in association have been examined in different stages and conditions. Then their usefulness in monitoring disease-free breast cancer patients is evaluated. The central role of the established cut-off and critical change, the "early" treatment of recurrent disease and the potential benefit in survival are other issues that have been highlighted and discussed. The successive sections and subsections deal with the monitoring of advanced disease. In them, the current recommendations and the principal findings on using the above mentioned mucins and cytokeratins have been reported. A computer program for interpreting consecutive measurements of serum tumor markers also has been illustrated. The final part of the chapter is devoted to mucins and cytokeratins as markers of circulating and disseminated tumor cells and their usefulness for prognosis.

Lynch syndrome-associated breast cancers do not overexpress chromosome 11-encoded mucins

Mismatch repair-deficient breast cancers may be identified in Lynch syndrome mutation carriers, and have clinicopathological features in common with mismatch repair-deficient colorectal and endometrial cancers such as tumour-infiltrating lymphocytes and poor differentiation. Mismatch repair-deficient colorectal cancers frequently show mucinous differentiation associated with upregulation of chromosome 11 mucins. The aim of this study was to compare the protein expression of these mucins in mismatch repair-deficient and -proficient breast cancers. Cases of breast cancer (n=100) were identified from families where (1) both breast and colon cancer co-occurred and (2) families met either modified Amsterdam criteria or had at least one early-onset (<50 years) colorectal cancer. Tumour sections were stained for the epithelial mucins, MUC2, MUC5AC, MUC5B and MUC6, and the homeobox protein CDX2, a regulator of MUC2 expression. In all, 16 mismatch repair-deficient Lynch syndrome breast cancers and 84 non-Lynch breast cancers were assessed for altered mucin expression. No significant difference in the expression of MUC2, MUC5AC or MUC6 was observed between the mismatch repair-deficient and mismatch repair-proficient breast cancers; however, there was a trend for mismatch repair-deficient tumours to express high levels of MUC5B less frequently (P=0.07, OR=0.2 (0.0-1.0)). Co-expression of two or more gel-forming mucins was common. Ectopic expression of CDX2 was associated with expression of MUC2 (P=0.035, OR=8.7 (1.3-58.4)). Mismatch repair-deficient breast cancers do not show differential expression of the mucins genes on chromosome 11 when compared with mismatch repair-proficient breast cancers, in contrast with mismatch repair-deficient colorectal and endometrial cancers, which frequently have increased mucin protein expression when compared with their mismatch repair-proficient counterparts. In addition, ectopic CDX2 expression is positively associated with de novo MUC2 expression.

Monoclonal antibodies toward different Tn-amino acid backbones display distinct recognition patterns on human cancer cells. Implications for effective immuno-targeting of cancer

The Tn antigen (GalNAcα-O-Ser/Thr) is a well-established tumor-associated marker which represents a good target for the design of anti-tumor vaccines. Several studies have established that the binding of some anti-Tn antibodies could be affected by the density of Tn determinant or/and by the amino acid residues neighboring O-glycosylation sites. In the present study, using synthetic Tn-based vaccines, we have generated a panel of anti-Tn monoclonal antibodies. Analysis of their binding to various synthetic glycopeptides, modifying the amino acid carrier of the GalNAc(*) (Ser* vs Thr*), showed subtle differences in their fine specificities. We found that the recognition of these glycopeptides by some of these MAbs was strongly affected by the Tn backbone, such as a S*S*S* specific MAb (15G9) which failed to recognize a S*T*T* or a T*T*T* structure. Different binding patterns of these antibodies were also observed in FACS and Western blot analysis using three human cancer cell lines (MCF-7, LS174T and Jurkat). Importantly, an immunohistochemical analysis of human tumors (72 breast cancer and 44 colon cancer) showed the existence of different recognition profiles among the five antibodies evaluated, demonstrating that the aglyconic part of the Tn structure (Ser vs Thr) plays a key role in the anti-Tn specificity for breast and colon cancer detection. This new structural feature of the Tn antigen could be of important clinical value, notably due to the increasing interest of this antigen in anticancer vaccine design as well as for the development of anti-Tn antibodies for in vivo diagnostic and therapeutic strategies.

MUC5B leads to aggressive behavior of breast cancer MCF7 cells

The mucin MUC5B has a critical protective function in the normal lung, salivary glands, esophagus, and gallbladder, and has been reported to be aberrantly expressed in breast cancer, the second leading cause of cancer-related deaths among women worldwide. To understand better the implication of MUC5B in cancer pathogenesis, the luminal human breast cancer cell line MCF7 was transfected with a vector encoding a recombinant mini-mucin MUC5B and was then infected with a virus to deliver a short hairpin RNA to knock down the mini-mucin. The proliferative and invasive properties in Matrigel of MCF7 subclones and subpopulations were evaluated in vitro. A xenograft model was established by subcutaneous inoculation of MCF7 clones and subpopulations in SCID mice. Tumor growth was measured, and the tumors and metastases were assessed by histological and immunological analysis. The mini-mucin MUC5B promoted MCF7 cell proliferation and invasion in vitro. The xenograft experiments demonstrated that the mini-mucin promoted tumor growth and MCF7 cell dissemination. In conclusion, MUC5B expression is associated with aggressive behavior of MCF7 breast cancer cells. This study suggests that MUC5B may represent a good target for slowing tumor growth and metastasis.

Abnormal expression of Muc5b in Cftr-null mice and in mammary tumors of MMTV-ras mice

Gel-forming mucins are large, high molecular weight, and heavily O-glycosylated proteins that are responsible for the rheological properties of mucus gel. Among them, the mucin MUC5B has been implicated in breast cancer and cystic fibrosis. We obtained a new polyclonal serum, named CP1, which was isolated from a rabbit immunized with a mouse Muc5b peptide. The immunoprofile of Muc5b was determined on paraffin-embedded and frozen mouse tissue sections and showed a similar expression pattern in mouse to that in the human. The "nonmammary" mucin Muc5b was detected in all mammary tumors analyzed from MMTV-ras mice, suggesting that the CP1 antibody is a valuable tool for investigating the involvement of this mucin in mammary cancer. We also found that uninfected Cftr( -/- ) mice harbored more Clara cells, which were Muc5b-positive, than did their wild-type control littermates. The number of Muc5b-positive cells increased in Cftr( -/- ) mice infected experimentally with Pseudomonas aeruginosa, and the mice developed mucus plugs in their bronchi and bronchioles with a high frequency of Muc5b content (87%, Cohen's kappa = 0.82; p < 0.0001). These findings suggest that mice genetically deficient in the Cftr gene are predisposed to develop mucus plugs and that MUC5B may provide a valuable target for decreasing mucus viscosity in cystic fibrosis.

Mucins in the pathogenesis of breast cancer: implications in diagnosis, prognosis and therapy

Mucins are high molecular weight, multifunctional glycoproteins comprised of two structural classes-the large transmembrane mucins and the gel-forming or secreted mucins. The primary function of mucins is to protect and lubricate the luminal surfaces of epithelium-lined ducts in the human body. Recent studies have identified a differential expression of both membrane bound (MUC1, MUC4 and MUC16) and secreted mucins (MUC2, MUC5AC, MUC5B and MUC6) in breast cancer tissues when compared with the non-neoplastic breast tissues. Functional studies have also uncovered many unique roles of mucins during the progression of breast cancer, which include modulation in proliferative, invasive and metastatic potential of tumor cells. Mucins function through many unique domains that can form complex association with various signaling molecules including growth factor receptors and intercellular adhesion molecules. While there is growing information about mucins in various malignancies including breast cancer, no focused review is there on the expression and functional roles of mucins in breast cancer. In this present review, we have discussed the differential expression and functional roles of mucins in breast cancer. The potential of mucins as diagnostic and prognostic markers and as therapeutic targets in breast cancer have also been discussed.

Inhibition of lamin A/C attenuates osteoblast differentiation and enhances RANKL-dependent osteoclastogenesis

Age-related osteoporosis is characterized by low bone mass, poor bone quality, and impaired osteoblastogenesis. Recently, the Hutchinson-Gilford progeria syndrome (HGPS), a disease of accelerated aging and premature osteoporosis, has been linked to mutations in the gene encoding for the nuclear lamina protein lamin A/C. Here, we tested the hypothesis that inhibition of lamin A/C in osteoblastic lineage cells impairs osteoblastogenesis and accelerates osteoclastogenesis. Lamin A/C was knocked-down with small interfering (si)RNA molecules in human bone marrow stromal cells (BMSCs) differentiating toward osteoblasts. Lamin A/C knockdown led to an inhibition of osteoblast proliferation by 26% and impaired osteoblast differentiation by 48% based on the formation of mineralized matrix. In mature osteoblasts, expression levels of runx2 and osteocalcin mRNA were decreased by lamin A/C knockdown by 44% and 78%, respectively. Furthermore, protein analysis showed that osteoblasts with diminished levels of lamin A/C also secreted less osteocalcin and expressed a lower alkaline phosphatase activity (-50%). Lamin A/C inhibition increased RANKL mRNA and protein levels, whereas osteoprotegerin (OPG) expression was decreased, resulting in an increased RANKL/OPG ratio and an enhanced ability to support osteoclastogenesis, as reflected by a 34% increase of TRACP(+) multinucleated cells. Our data indicate that lamin A/C is essential for proper osteoblastogenesis. Moreover, lack of lamin A/C favors an osteoclastogenic milieu and contributes to enhanced osteoclastogenesis.

Cancer micrometastasis and tumour dormancy

Many epithelial cancers carry a poor prognosis even after curative resection of early stage tumours. Tumour progression in these cancer patients has been attributed to the existence and persistence of disseminated tumour cells (DTC) in various body compartments as a sign of minimal residual disease. Bone marrow (BM) has been shown to be a common homing organ and reservoir for DTC. A significant correlation between the presence of DTC in BM and metastatic relapse has been reported in various tumour types. However, only a portion of patients with DTC in BM at primary surgery relapse. Thus far, little is known about the conditions required for the persistence of dormancy or the escape from the dormant phase into the active phase of metastasis formation. Thereby, this peculiar stage of conceivably balanced tumour cell division and death may last for decades in cancer patients. Most likely, the ability of a dormant DTC to "be activated" is a complex process involving (i) somatic aberrations in the tumour cells, (ii) the interaction of the DTC with the new microenvironment at the secondary site, and (iii) hereditary components of the host (i.e., cancer patient). In this review, we will summarize the key findings of research on micrometastatic cancer cells and discuss these findings in the context of the concept of tumour dormancy.

Review: Biological relevance of disseminated tumor cells in cancer patients

The prognosis of cancer patients is largely determined by the occurrence of distant metastases. In patients with primary tumors, this relapse is mainly due to clinically occult micrometastasis present in secondary organs at primary diagnosis but not detectable even with high resolution imaging procedures. Sensitive and specific immunocytochemical and molecular assays enable the detection and characterization of disseminated tumor cells (DTC) at the single cell level in bone marrow (BM) as the common homing site of DTC and circulating tumor cells (CTC) in peripheral blood. Because of the high variability of results in DTC and CTC detection, there is an urgent need for standardized methods. In this review, we will focus on BM and present currently available methods for the detection and characterization of DTC. Furthermore, we will discuss data on the biology of DTC and the clinical relevance of DTC detection. While the prognostic impact of DTC in BM has clearly been shown for primary breast cancer patients, less is known about the clinical relevance of DTC in patients with other carcinomas. Current findings suggest that DTC are capable to survive chemotherapy and persist in a dormant nonproliferating state over years. To what extent these DTC have stem cell properties is subject of ongoing investigations. Further characterization is required to understand the biology of DTC and to identify new targets for improved risk prevention and tailoring of therapy. Our review will focus on breast, colon, lung, and prostate cancer as the main tumor entities in Europe and the United States.

Significance of micrometastasis in bone marrow and blood of operable breast cancer patients: research tool or clinical application?

Approximately 25% of breast cancer patients without lymph node metastases develop systemic relapse. A growing body of data supports the notion that hematogenous dissemination of breast cancer cells occurs independently of lymphatic spread of disease; however, current clinical practice does not involve routine analysis of circulating or disseminated cells. Recent studies have documented that both circulating tumor cells (CTCs) within the blood and disseminated tumor cells (DTCs) in bone marrow can be identified using a variety of techniques. It is now clear that the presence of DTCs correlates with subsequent development of clinically evident bone metastases, and a worse outcome from breast cancer. While there are data identifying prognostic significance of CTCs in patients with metastatic breast cancer, there are few data regarding CTCs in operable patients. Factors such as presence of a cancer stem cell phenotype and/or certain microenvironmental conditions are involved in the establishment of distant metastases from a primary breast cancer, emphasizing the need for further studies within this area. The purpose of this report is to review the data regarding CTCs and DTCs in patients with operable breast cancer.

Application of immunomagnetic cell enrichment in combination with RT-PCR for the detection of rare circulating head and neck tumor cells in human peripheral blood

Detection of rare, circulating tumor cells (CTC's) in human peripheral blood is a potential indicator of prognosis and diagnosis in oncology. Typical methods to detect these CTC's are either by immunocytochemistry (ICCS) or RT-PCR. However without accurate, rapid, and reproducible enrichment processes, these detection techniques are labor intensive and/or unreliable. In this article, a repeatable enrichment process that included a flow-through immunomagnetic cell separation system, the quadrupole magnetic sorter (QMS) was optimized with the aid of a statistical analysis software package. The QMS was operated in a negative mode of operation by immunomagnetically targeting normal human peripheral blood lymphocytes (PBL) through the CD45 surface marker. Three head and neck squamous carcinoma cell lines (HNSCC), Detroit-562, SCC-4, and CAL-27, were used to determine the sensitivity of RT-PCR for the epidermal growth factor receptor (EGFR) in spiked PBL. The detection purity needed for detection was found to be one cell in 10(4), one cell in 10(3), and one cell in 10(5) for the Detroit-562, SCC-4, and CAL-27, respectively. The actual number of cancer cells needed for RT-PCR detection ranged from 30 to 1 cell. To mimic the potential concentration of rare CTC present in peripheral blood of cancer patients, the spiking concentration was chosen to be one cancer cell per 10(5) total leukocytes from healthy donors. Using a single step immunomagnetic labeling, the final, optimized enrichment process produced a 57.6 +/- 30.3-fold (n = 6) enrichment of the rare cancer cells with a final cancer cell recovery of (77.8 +/- 6.6)%.

Biomarkers in breast cancer

Breast cancer is one of the most frequently diagnosed cancers among women in the western world. Due to the aggressive behaviour of some specific types and the possibility of an early diagnosis, breast cancer has been constantly studied. Tumour size, histological type, cellular and nuclear characteristics, mitotic index, vascular invasion, hormonal receptors and axillary lymph node status are biomarkers routinely used. However, these parameters are not enough to predict the course of this disease. Molecular biology advances have made it possible to find new markers, which have already been incorporated to the clinical practice. Their ultimate goal is to reduce mortality by identifying women at risk for the development of this disease, help diagnosis, determine prognosis, detect recurrences, monitor and guide treatment, and in particular cancers they are suited for general screening. Tumour markers in breast cancer were ranked in categories reflecting their clinical utility, according to the American College of Pathologists.

This article focuses on traditional and new molecular markers stratifying them into categories and emphasizing their relevance in the routine evaluation of patients with breast cancer.

Expression analysis of stage III serous ovarian adenocarcinoma distinguishes a sub-group of survivors

It is difficult to predict the clinical outcome for patients with ovarian cancer. However, the use of biomarkers as additional prognostic factors may improve the outcome for these patients. In order to find novel candidate biomarkers, differences in gene expressions were analysed in 54 stage III serous ovarian adenocarcinomas with oligonucleotide microarrays containing 27,000 unique probes. The microarray data was verified with quantitative real-time polymerase chain reaction for the genes TACC1, MUC5B and PRAME. Using hierarchical cluster analysis we detected a sub-group that included 60% of the survivors. The gene expressions in tumours from patients in this sub-group of survivors were compared with the remaining tumours, and 204 genes were found to be differently expressed. We conclude that the sub-group of survivors might represent patients with favourable tumour biology and sensitivity to treatment. A selection of the 204 genes might be used as a predictive model to distinguish patients within and outside of this group. Alternative chemotherapy strategies could then be offered as first-line treatment, which may lead to improvements in the clinical outcome for these patients.

UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 6 (ppGalNAc-T6) mRNA as a potential new marker for detection of bone marrow-disseminated breast cancer cells

The evaluation of disseminated epithelial tumor cells in patients with early stages of breast cancer has generated considerable interest because of its potential association with poor clinical outcome. Considering that O-glycosylation pathways are frequently altered in breast cancer, we performed this work to evaluate the potential usefulness of UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts) (a family of glycosyltransferases which catalyze the first key step of mucin-type O-glycosylation) to detect disseminated cells in bone marrow samples from patients with operable breast cancer. Using RT-PCR assays, we studied the gene expression of 9 enzymes (ppGalNAc-T1-T9). Among the ppGalNAc-Ts expressed by breast tumors (-T1, -T2, -T3, -T6 and -T7), the best specificity (negative results on all PBMN cell samples from healthy donors) was shown for ppGalNAc-T6. Thus, we selected this enzyme as a target gene for further evaluation. ppGalNAc-T6 mRNA was found in 22/25 (88%) breast cancer samples, in all 3 human breast cancer cell lines evaluated (MCF-7, ZR75-1 and T47D), in 1/30 (3%) PBMN cells and 0/19 bone marrow samples obtained from patients without cancer. Using this method, 22/61 (36%) patients with breast cancer, who underwent curative surgery, showed positive ppGalNAc-T6 mRNA in bone marrow aspirates obtained prior to surgery, including 11/34 patients with stage-I or -II, without histopathological lymph node involvement. In a preliminary follow-up evaluation, 19/61 patients experienced recurrence of the disease. ppGalNAc-T6 was positive in 11/19 (57.9%) of these patients. Interestingly, in the group of patients without lymph node involvement, disease recurrence was observed in 54.5% of patients who showed ppGalNAc-T6 mRNA-positive bone marrow aspirates and only in 4.3% of patients when ppGalNAc-T6 was negative (p = 0.014). These results indicate that ppGalNAc-T6 mRNA could be a specific marker applicable to the molecular diagnosis of breast cancer cells dissemination.

Prognostic value of mucins in the classification of ampullary carcinomas

The ampulla of Vater is of high clinical relevance with regard to influx of chyme, ascending inflammation, intubation during diagnostic and therapeutic endoscopic investigation, therapeutic papillotomy, and especially to malignant transformation. Little is known about the distribution of mucins in the ampulla. In this study, we have investigated the mucin distribution in the normal ampulla of Vater and compared it to duodenal mucosa and Brunner glands. Expression of mucins in the ampulla of Vater and duodenum was monitored by reverse transcription-polymerase chain reaction and localization of the products by immunohistochemistry. The samples investigated originated from 30 autopsy cases. Mucins MUC1, MUC3, MUC4, MUC5AC, MUC5B, MUC6, MUC7, and MUC8 were expressed in the ampulla of Vater. Immunohistochemistry revealed production of MUC4, MUC5AC, MUC5B, and MUC6. The mucin composition varied in comparison with the duodenum referring to MUC2, MUC7, and MUC8. Detected mucins contribute to innate immunity, epithelial restitution, and protection against the aggressive secretions of the liver, gall bladder, and pancreas. By cross-linking, they influence the rheological properties of the secretions in the ampulla and facilitate unidirectional flow into the duodenum. Knowledge of their pattern of expression has prognostic value with regard to the detection of malignancy. The observed differences in the mucin distribution between the duodenum and the ampulla of Vater support the use of MUC2, MUC7, and MUC8 as useful tool in the classification of ampullary carcinomas.

Selective identification of secreted and transmembrane breast cancer markers using Escherichia coli ampicillin secretion trap

Secreted and cell surface proteins play important roles in cancer and are potential drug targets and tumor markers. Here, we describe a large-scale analysis of the genes encoding secreted and cell surface proteins in breast cancer. To identify these genes, we developed a novel signal sequence trap method called Escherichia coli ampicillin secretion trap (CAST). For CAST, we constructed a plasmid in which the signal sequence of beta-lactamase was deleted such that it does not confer ampicillin resistance. Eukaryotic cDNA libraries cloned into pCAST produced tens of thousands of ampicillin-resistant clones, 80% of which contained cDNA fragments encoding secreted and membrane spanning proteins. We identified 2,708 unique sequences from cDNA libraries made from surgical breast cancer specimens. We analyzed the expression of 1,287 of the 2,708 genes and found that 166 were overexpressed in breast cancers relative to normal breast tissues. Eighty-five percent of these genes had not been previously identified as markers of breast cancer. Twenty-three of the 166 genes (14%) were relatively tissue restricted, suggesting use as cancer-specific targets. We also identified several new markers of ovarian cancer. Our results indicate that CAST is a robust, rapid, and low cost method to identify cell surface and secreted proteins and is applicable to a variety of relevant biological questions.

Immunohistochemical analysis of MUC5B apomucin expression in breast cancer and non-malignant breast tissues

A deregulation of several MUC genes (MUC1, MUC2, MUC3, MUC5AC, and MUC6) was previously demonstrated in breast carcinomas. Considering that recently we found the "non-mammary" MUC5B mRNA in primary breast tumors (Berois et al. 2003), we undertook the present study to evaluate the expression profile of MUC5B protein product in breast tissues, using LUM5B-2 antisera raised against sequences within the non-glycosylated regions of this apomucin. Expression of MUC5B by breast cancer cells was confirmed by immunocytochemistry, in situ hybridization, and Western blot on MCF-7 cancer cells. Using an immunohistochemical procedure, MUC5B apomucin was detected in 34/42 (81%) primary breast tumors, in 13/14 (92.8%) samples of non-malignant breast diseases, in 8/19 (42.1%) samples of normal-appearing breast epithelia adjacent to cancer, and in 0/5 normal control breast samples. The staining pattern of MUC5B was very different when comparing breast cancer cells (cytoplasmic) and non-malignant breast cells (predominantly apical and in the secretory material). We analyzed MUC5B mRNA expression using RT-PCR in bone marrow aspirates from 22/42 patients with breast cancer to compare with MUC5B protein expression in the primary tumors. Good correlation was observed because the six MUC5B-positive bone marrow samples also displayed MUC5B expression in the tumor. Our results show, for the first time at the protein level, that MUC5B apomucin is upregulated in breast cancer. Its characterization could provide new insights about the glycobiology of breast cancer cells.

Molecular Basis of Incomplete O-Glycan Synthesis in MCF-7 Breast Cancer Cells: Putative Role of MUC6 in Tn Antigen Expression

An incomplete elongation of O-glycan saccharide chains in mucins have been found in epithelial cancers, leading to the expression of shorter carbohydrate structures, such as the Tn antigen (GalNAc-O-Ser/Thr). This antigen is one of the most specific human cancer-associated structures and is capable of inducing effective immune responses against cancer cells. We aimed to investigate the causes of the expression of Tn antigen in the Tn-rich MCF-7 breast cancer cell line focusing on the first step of the O-glycosylation process. Interestingly, amino acid sequences derived from "non-mammary" apomucins (MUC5B and MUC6) were very good acceptor substrates for ppGalNAc-Ts, which are the enzymes catalyzing the Tn antigen synthesis. MUC6 peptide glycosylation with MCF-7 microsome extracts as source of ppGalNAc-T activity yielded 95% conversion of the peptide into MUC6-Tn. In addition, the MUC6-Tn glycopeptide was a poor acceptor substrate for core 1 beta3Gal-T, the next enzyme involved in the saccharide chain biosynthesis, yielding only 5% conversion of MUC6-Tn into MUC6-TF. These results indicate that non-mammary apomucin expression could be responsible, at least in part, for Tn antigen expression in MCF-7 breast cancer cells due to a combined action on glycosyltransferases: an increase of ppGalNAc-T activity and a decrease of core 1 beta3Gal-T activity. Our hypothesis is supported by experiments in vivo showing that (a) native MUC6 glycoproteins express the Tn antigen in MCF-7 cells and (b) Tn antigen expression is increased after transfection with a construct encoding for a MUC6 recombinant protein into the low Tn-expressing breast cancer cell T47D. These results open new horizons in breast cancer glycoimmunology, stressing the potential role of non-mammary apomucins.

Detection of lymph node micrometastasis in gastric cancer by MUC2 RT-PCR: usefulness in pT1 cases

BACKGROUND AND OBJECTIVES

The objectives of this study were to evaluate the clinical utility of MUC2-specific reverse transcriptase-polymerase chain reaction (RT-PCR) in gastric cancer patients and to compare MUC2-specific RT-PCR to carcinoembryonic antigen (CEA)-specific RT-PCR.

METHODS

A total of 305 lymph nodes from 28 patients with gastric cancer were histologically examined and analyzed by MUC2 RT-PCR and CEA RT-PCR.

RESULTS

MUC2 and CEA were expressed in 17.1 and 7.0% of the 286 histologically negative lymph nodes, respectively. The detection rate of MUC2 was significantly higher than that of CEA (P < 0.01). MUC2 RT-PCR revealed no false positive results in control specimens. Lymph node micrometastases in pT1 gastric cancer were expressed only in perigastric lymph nodes near the tumor and were not detected in tumor less than 30 mm in patients with mucosal cancer.

CONCLUSIONS

MUC2-specific RT-PCR is a sensitive and specific method to detect lymph node micrometastases in gastric cancer patients. The distribution of lymph node micrometastases detected by this method may be useful in minimally invasive procedures for gastric cancer, especially pT1 cases.

Role of caspase activation in butyrate-induced terminal differentiation of HT29 colon carcinoma cells

Colon epithelial cells have a defined life span and undergo terminal differentiation as they mature and migrate to the luminal surface. The differentiation process can be induced in cultured colon cancer cells by sodium butyrate, which induces expression of various differentiation markers followed subsequently by cell death. In the present study, HT29 colorectal carcinoma cells were shown to undergo butyrate-induced caspase activation that was mainly produced through a mitochondrial pathway. Inhibition of caspase activation, either by peptide pan caspase inhibitor Z-VAD-FMK, by caspase 9 inhibitor Z-LEHD-FMK, or by overexpression of Bcl-XL, also inhibited the expression of differentiation markers. These findings suggest (a) that terminal differentiation of HT29 colon carcinoma cells is tightly linked to caspase activation and (b) that increased expression of anti-apoptotic members of the Bcl-2 family of proteins, as well as other inhibitors of caspase activation, has the potential to inhibit terminal differentiation and thereby may contribute to the progression of colon cancer.