p38MAPK induces cell surface alpha4 integrin downregulation to facilitate erbB-2-mediated invasion

"A Review of HER2 overexpression and somatic mutations in cancers"

The Human Epidermal Growth Factor Receptor (HER) proteins family, which includes HER2, are membrane-bound receptors that activate many intracellular pathways associated with growth and development. When there are mutations in HER2, or when it becomes overexpressed, it can cause oncogenesis and offer differential prognosis and treatment across almost all cancer types. Both mutations in HER2 and its overexpression have distinct mechanisms by which they can cause these effects in cancers. This review outlines how HER2's normal pathway is altered in both overexpression and mutation and compiles all the well-known mechanisms by which HER2 can cause oncogenesis. Finally, this review briefly outlines how HER2 mutants and HER2 overexpression is detected, and how their detection can lead to different prognosis and treatment in cancers.

Nanolipoprotein-Mediated Her2 Protein Transfection Induces Malignant Transformation in Human Breast Acinar Cultures

Her2 overexpression is associated with an aggressive form of breast cancer and malignant transformation. We demonstrate in this work that nanolipoprotein particles (NLPs) synthesized in a cell-free manner can be used to transfer Her2 protein into the membrane of nonmalignant cells in 3D culture in a nontoxic and facile manner. With NLP-mediated Her2 protein delivery, we observed an increased probability of nonmalignant cells forming apolar nongrowth-arrested tumor-like structures. The NLP delivery system alone or Her2-NLPs plus the Her2 inhibitor trastuzumab showed no effect on the acinar organization rate, indicating that Her2 signaling is key to this process. Transcriptomics revealed essentially no effect of empty NLPs compared to untreated cells, whereas Her2-NLPs versus either untreated or empty-NLP-treated cells revealed upregulation of several factors associated with breast cancer. Pathway analysis also suggested that known nodes downstream of Her2 were activated in response to Her2-NLP treatment. This demonstrates that Her2 protein delivery with NLPs is sufficient for the malignant transformation of nonmalignant cells. Thus, this system offers a new model for studying cell surface receptor signaling without genomic modification or transformation techniques.

Functional Common and Rare ERBB2 Germline Variants Cooperate in Familial and Sporadic Cancer Susceptibility

We investigated a Spanish and Catalan family in which multiple cancer types tracked across three generations, but for which no genetic etiology had been identified. Whole-exome sequencing of germline DNA from multiple affected family members was performed to identify candidate variants to explain this occurrence of familial cancer. We discovered in all cancer-affected family members a single rare heterozygous germline variant (I654V, rs1801201) in ERBB2/HER2, which is located in a transmembrane glycine zipper motif critical for ERBB2-mediated signaling and in complete linkage disequilibrium (D' = 1) with a common polymorphism (I655V, rs1136201) previously reported in some populations as associated with cancer risk. Because multiple cancer types occurred in this family, we tested both the I654V and the I655V variants for association with cancer across multiple tumor types in 6,371 cases of Northern European ancestry drawn from The Cancer Genome Atlas and 6,647 controls, and found that the rare variant (I654V) was significantly associated with an increased risk for cancer (OR = 1.40; P = 0.021; 95% confidence interval (CI), 1.05-1.89). Functional assays performed in HEK 293T cells revealed that both the I655V single mutant (SM) and the I654V;I655V double mutant (DM) stabilized ERBB2 protein and activated ERBB2 signaling, with the DM activating ERBB2 significantly more than the SM alone. Thus, our results suggest a model whereby heritable genetic variation in the transmembrane domain activating ERBB2 signaling is associated with both sporadic and familial cancer risk, with increased ERBB2 stabilization and activation associated with increased cancer risk. PREVENTION RELEVANCE: By performing whole-exome sequencing on germline DNA from multiple cancer-affected individuals belonging to a family in which multiple cancer types track across three generations, we identified and then characterized functional common and rare variation in ERBB2 associated with both sporadic and familial cancer. Our results suggest that heritable variation activating ERBB2 signaling is associated with risk for multiple cancer types, with increases in signaling correlated with increases in risk, and modified by ancestry or family history.

Evolution of anti-HER2 therapies for cancer treatment

The development of HER2-directed monoclonal antibodies and tyrosine kinase inhibitors have provided benefits to cancer patients, as well as produced many insights into the biology of the ErbB receptor family. Current therapies based on ErbB family members have resulted in improved overall survival with associated improvements in quality of life for the cancer patients that respond to treatment. Compared to monotherapy using either two antibodies to block the HER2 receptor blockade or combinatorial approaches with HER2 antibodies and standard therapies has provided additional benefits. Despite the therapeutic success of existing HER2 therapies, personalising treatment and overcoming resistance to these therapies remains a significant challenge. The heterogeneous intra-tumoural HER2 expression and lack of fully predictive and prognostic biomarkers remain significant barriers to improving the use of HER2 antibodies. Imaging modalities using radiolabelled pertuzumab and trastuzumab allow quantitative assessment of intra-tumoural HER2 expression, HER2 antibody saturation and the success of different drug delivery systems to be assessed. Molecular imaging with HER2 antibodies has the potential to be a non-invasive, predictive and prognostic technique capable of influencing therapeutic decisions, predicting response and failure of treatments as well as providing insights into receptor recycling and signalling. Similarly, conjugating HER2 antibodies with novel toxic payloads or combining HER2 antibodies with cellular immunotherapy provide exciting new opportunities for the management of tumours overexpressing HER2. Future research will lead to higher therapeutic responses, lower toxicities and providing insight into the mechanisms of resistance to HER2-targeted treatments.

Therapeutic inhibition of breast cancer bone metastasis progression and lung colonization: breaking the vicious cycle by targeting α5β1 integrin

At diagnosis, 10 % of breast cancer patients already have locally advanced or metastatic disease; moreover, metastasis eventually develops in at least 40 % of early breast cancer patients. Osteolytic bone colonization occurs in 80-85 % of metastatic breast cancer patients and is thought to be an early step in metastatic progression. Thus, breast cancer displays a strong preference for metastasis to bone, and most metastatic breast cancer patients will experience its complications. Our prior research has shown that the α5β1 integrin fibronectin receptor mediates both metastatic and angiogenic invasion. We invented a targeted peptide inhibitor of activated α5β1, Ac-PHSCN-NH2 (PHSCN), as a validated lead compound to impede both metastatic invasion and neovascularization. Systemic PHSCN monotherapy prevented disease progression for up to 14 months in Phase I clinical trial. Here, we report that the next-generation construct, Ac-PhScN-NH2 (PhScN), which contains D-isomers of histidine (h) and cysteine (c), is greater than 100,000-fold more potent than PHSCN at blocking basement membrane invasion. Moreover, PhScN is also up to 10,000-fold more potent than PHSCN at inhibiting lung extravasation and colonization in athymic mice for both MDA-MB-231 metastatic and SUM149PT inflammatory breast cancer cells. Furthermore, we show that systemic treatment with 50 mg/kg PhScN monotherapy reduces established intratibial MDA-MB-231 bone colony progression by 80 %. Thus, PhScN is a highly potent, well-tolerated inhibitor of both lung colonization and bone colony progression.

Determination of the Proteomic Response to Lapatinib Treatment using a comprehensive and reproducible ion-current-based proteomics strategy

Lapatinib, a small molecule tyrosine kinase inhibitor is currently used in the treatment of HER2-positive breast cancer. The aim of this study was to further understanding of lapatinib response for the development of novel treatment lapatinib-focussed treatment strategies. HER2-overexpressing SKBR3 breast cancer cells were treated with lapatinib for 12 hours and the resultant proteome analyzed by a comprehensive ion-current-based LC-MS strategy. Among the 1224 unique protein identified from SKBR3 cell lysates, 67 showed a significant change in protein abundance in response to lapatinib. Of these, CENPE a centromeric protein with increased abundance, was chosen for further validation. Knockdown and inhibition of CENPE demonstrated that CENPE enhances SKBR3 cell survival in the presence of lapatinib. Based on this study, CENPE inhibitors may warrant further investigation for use in combination with lapatinib.

Novel anticancer alkene lactone from Persea americana

CONTEXT

Persea americana Mill (Lauraceae) root bark is used in ethnomedicine for a variety of diseases including cancer.

OBJECTIVE

To isolate and characterize the chemical constituent in P. americana, and also to determine the anticancer property of a new alkene lactone from the root bark of P. americana.

MATERIALS AND METHODS

The MCF-7 cells were treated with different concentrations of the pure compound for 48 h. The percentage of cells in the various phases, online monitoring of metabolic changes and integrin receptor expression determined by flow cytometry.

RESULTS

One novel alkene lactone (4-hydroxy-5-methylene-3-undecyclidenedihydrofuran-2 (3H)-one) (1) was isolated and characterized using 1D-NMR, 2D-NMR, infrared, UV and MS. At a concentration of 10 µg/mL, significant reduction of proliferation of MCF-7 was induced while MCF-12 A cell was significantly stimulated by 10 µg/mL. The IC50 value for MCF-7 cells is 20.48 µg/mL. Lower concentration of 1 harbor no significant effect on either MCF-7 or MCF-12A. The apoptotic rates of MCF-7 cells were increased significantly. At the final concentration 10 µg/mL, up to 80% of all breast cancer cells were dead. On the non-tumorigenic cell line MCF-12A, the same concentrations (1 and 10 µg/mL) of compound 1 caused significant enhanced apoptotic rates. A total of 1 µg/mL of 1 caused a decrease of α4-, α6-, β1- and β3-integrin expression.

CONCLUSIONS

The compound caused a stimulatory effect on non-tumorigenic MCF-12A cells with respect to cell adhesion while tumorigenic MCF-7 cells detached continuously. This is the first report on the anticancer effects of this class of compound.

Increased potency of the PHSCN dendrimer as an inhibitor of human prostate cancer cell invasion, extravasation, and lung colony formation

Activated alpha5beta1 integrin occurs specifically on tumor cells and on endothelial cells of tumor-associated vasculature, and plays a key role in invasion and metastasis. The PHSCN peptide (Ac-PHSCN-NH(2)) preferentially binds activated alpha5beta1, to block invasion in vitro, and inhibit growth, metastasis and tumor recurrence in preclinical models of prostate cancer. In Phase I clinical trial, systemic Ac-PHSCN-NH(2) monotherapy was well tolerated, and metastatic disease progression was prevented for 4-14 months in one-third of treated patients. We have developed a significantly more potent derivative, the PHSCN-polylysine dendrimer (Ac-PHSCNGGK-MAP). Using in vitro invasion assays with naturally serum-free basement membranes, we observed that the PHSCN dendrimer was 130- to 1900-fold more potent than the PHSCN peptide at blocking alpha5beta1-mediated invasion by DU 145 and PC-3 human prostate cancer cells, whether invasion was induced by serum, or by the Ac-PHSRN-NH(2) peptide, under serum-free conditions. The PHSCN dendrimer was also approximately 800 times more effective than PHSCN peptide at preventing DU 145 and PC-3 extravasation in the lungs of athymic mice. Chou-Talalay analysis suggested that inhibition of both invasion in vitro and extravasation in vivo by the PHSCN dendrimer are highly synergistic. We found that many extravasated DU 145 and PC-3 cells go onto develop into metastatic colonies, and that a single pretreatment with the PHSCN dendrimer was 100-fold more affective than the PHSCN peptide at reducing lung colony formation. Since many patients newly diagnosed with prostate cancer already have locally advanced or metastatic disease, the availability of a well-tolerated, nontoxic systemic therapy, like the PHSCN dendrimer, which prevents metastatic progression by inhibiting invasion, could be very beneficial.

17β-estradiol enhances α(5) integrin subunit gene expression through ERα-Sp1 interaction and reduces cell motility and invasion of ERα-positive breast cancer cells

In breast tumors the expression of estrogen receptor alpha (ERα) is known to be associated with a more favorable prognosis. ERα expression has been reported to reduce the metastatic potential of breast cancer cells. Recently, we have observed that extracellular matrix proteins activate ERα and that both liganded and unliganded receptor modulate cell invasiveness acting at nuclear level. To explain the mechanisms by which ERα regulates cell adhesion, we have evaluated the expression of α(5)β(1) integrin, prevalently expressed in stationary cells, in response to 17β-estradiol (E2). Here we show that E2/ERα increases the expression of integrin α(5)β(1) through Sp1-mediated binding to a GC-rich region located upstream of an ERE half-site in the 5' flanking region of the α(5) gene forming a ternary ERα-Sp1-DNA complex. Estrogen responsiveness of the α(5) gene promoter, as observed in HeLa cells, underlies a general mechanism of regulation which is not strictly linked to the cell type. Our data reveal novel insight into the molecular mechanisms sustaining the reduced invasiveness of ERα expressing cells demonstrating that α(5)β(1) integrin expression is related to the maintenance of the stationary status of the cells, counteracting E2/ERα capability to enhance breast cancer cell migration and invasion.

NADPH oxidase 1 controls the persistence of directed cell migration by a Rho-dependent switch of alpha2/alpha3 integrins

NADPH oxidase 1 (Nox1) is expressed mainly in colon epithelial cells and produces superoxide ions as a primary function. We showed that Nox1 knockdown inhibits directional persistence of migration on collagen I. This paper dissects the mechanism by which Nox1 affects the direction of colonic epithelial cell migration in a two-dimensional model. Transient activation of Nox1 during cell spreading on collagen 1 temporarily inactivated RhoA and led to efficient exportation of alpha2beta1 integrin to the cell surface, which supported persistent directed migration. Nox1 knockdown led to a loss of directional migration which takes place through a RhoA-dependent alpha2/alpha3 integrin switch. Transient RhoA overactivation upon Nox1 inhibition led to transient cytoskeletal reorganization and increased cell-matrix contact associated with a stable increase in alpha3 integrin cell surface expression. Blocking of alpha3 integrin completely reversed the loss of directional persistence of migration. In this model, Nox1 would represent a switch between random and directional migration through RhoA-dependent integrin cell surface expression modulation.

ErbB receptors and cell polarity: new pathways and paradigms for understanding cell migration and invasion

The ErbB family of receptor tyrosine kinases is involved in initiation and progression of a number of human cancers, and receptor activation or overexpression correlates with poor patient survival. Research over the past two decades has elucidated the molecular mechanisms underlying ErbB-induced tumorigenesis, which has resulted in the development of effective targeted therapies. ErbB-induced signal transduction cascades regulate a wide variety of cell processes, including cell proliferation, apoptosis, cell polarity, migration and invasion. Within tumors, disruption of these core processes, through cooperative oncogenic lesions, results in aggressive, metastatic disease. This review will focus on the ErbB signaling networks that regulate migration and invasion and identify a potential role for cell polarity pathways during cancer progression.

p38MAPK-activated AKT in HER-2 overexpressing human breast cancer cells acts as an EGF-independent survival signal

BACKGROUND

HER-2 is an epidermal growth factor receptor (EGFR) family receptor tyrosine kinase that is overexpressed in about 30% of human breast cancers correlating with a poor prognosis. Previous work in our laboratory has found that HER-2 overexpression plays a role in growth factor independence, anchorage independence, motility, and invasion of naturally occurring basement membranes. We also found that AKT was activated by p38MAPK in these cells, but this activation did not play a role in invasion. Since AKT has been shown in other systems to be a survival factor, we hypothesized that HER-2 mediated activation of AKT is necessary for growth factor independence.

METHODS

Human mammary epithelial cells transduced to overexpress HER-2, HER-2, PTEN, and Myr-AKT and the primary breast cancer cell lines SUM-149 and SUM-225 were used to dissect the signaling pathways leading to growth factor independence and anchorage-independent growth in HER-2 overexpressing cells.

RESULTS

We found that, in the absence of EGF, p38MAPK-activated AKT is necessary for HER-2 overexpressing cells to survive and to form colonies in soft agar. We show that EGF works as a survival signal in the absence of p38MAPK-mediated activation of AKT. We also show that human mammary epithelial cells expressing a constitutively active AKT do not require EGF for growth or colony formation in soft agar.

CONCLUSIONS

The data presented here indicate that AKT activation can compensate for EGF-mediated cell survival signals leading to growth factor independence and anchorage-independent growth.

The oncogene HER2: its signaling and transforming functions and its role in human cancer pathogenesis

The year 2007 marks exactly two decades since Human Epidermal Growth Factor Receptor-2 (HER2) was functionally implicated in the pathogenesis of human breast cancer. This finding established the HER2 oncogene hypothesis for the development of some human cancers. The subsequent two decades have brought about an explosion of information about the biology of HER2 and the HER family. An abundance of experimental evidence now solidly supports the HER2 oncogene hypothesis and etiologically links amplification of the HER2 gene locus with human cancer pathogenesis. The molecular mechanisms underlying HER2 tumorigenesis appear to be complex and a unified mechanistic model of HER2-induced transformation has not emerged. Numerous hypotheses implicating diverse transforming pathways have been proposed and are individually supported by experimental models and HER2 may indeed induce cell transformation through multiple mechanisms. Here I review the evidence supporting the oncogenic function of HER2, the mechanisms that are felt to mediate its oncogenic functions, and the evidence that links the experimental evidence with human cancer pathogenesis.

Detection of HER-2/neu gene amplification in breast carcinomas using quantitative real-time PCR - a comparison with immunohistochemical and FISH results

The aim of our study was to evaluate the value of quantitative real-time-PCR (qPCR) in the determination of HER-2/neu amplification status of human breast carcinomas by comparing qPCR, FISH and immunohistochemistry results from the same samples. A total of 210 breast carcinomas were examined. Ready-to-use CB11 antibody was applied to detect HER-2/neu oncoprotein expression. In 76 out of 210 cases FISH was performed, and 162 cases were investigated with qPCR. Seventy-five tumors were 2+ or 3+ positive with immunohistochemistry, while 135 samples were either completely negative or 1+. In 45 cases results from all three methods were available. Out of these, in twenty negative and sixteen positive cases both FISH and qPCR led to similar results. The mean qPCR amplification ratio in the concordant positive cases was 5.424 while in the qPCR+/FISH- group the mean ratio was 2.765. Out of 121 samples with scores of 0 or 1+ immunohistochemical result, analyzed also with qPCR, 26 showed HER-2/neu gene amplification. In these cases the mean amplification ratio was 2.53. Comparison of FISH and qPCR together with immunohistochemistry shows that qPCR is more sensitive to detect HER-2/neu gene amplification in tumors scored as 2+ with immunohistochemistry, but the diagnostic cut-off ratio should be defined above 2.7 to avoid high number of false positive cases. Amongst the immunohistochemistry score 2+ cases, 10 of 18 showed gene amplification by qPCR while 10 of 26 by FISH. In conclusion, a well calibrated HER-2/neu qPCR assay may serve as useful alternative to FISH in breast cancer patients.

VCAM-1 inhibits TGFβ stimulated epithelial–mesenchymal transformation by modulating Rho activity and stabilizing intercellular adhesion in epicardial mesothelial cells

Regulation of epithelial-mesenchymal transformation (EMT) is of central importance both in normal development and in disease. During heart development, cells of the superficial epicardial mesothelium undergo EMT to give rise to precursor cells of the coronary vasculature and cardiac fibroblasts. Here we report that the alpha(4)beta(1) integrin ligand, VCAM-1, inhibits EMT of chick epicardial mesothelial cells stimulated by TGFbeta isoforms. We further investigated the molecular basis of this inhibition using cultured chick embryonic and rat adult epicardial mesothelial cells. We observed that VCAM-1 increased cortical actin filaments at intercellular junctions and reduced stress fibers across epicardial cells. VCAM-1 inhibited stress fiber formation by TGFbeta1, TGFbeta2, TGFbeta3 and lysophosphatidic acid and altered Rho activity stimulated by TGFbeta3. This was accompanied by an increase in tyrosine phosphorylation of p190RhoGAP. All three TGFbeta isoforms weakened intercellular adhesion, reduced membrane localization of beta-catenin and E-cadherin and stimulated epicardial EMT in chick hearts. Each of these effects was restricted by simultaneous VCAM-1 treatment. Our data support the hypothesis that VCAM-1 can alter epicardial EMT at two key points: it limits Rho-dependent events such as stress fiber formation and it maintains the association of beta-catenin and E-cadherin with the adherens junction.

Role of Focal Adhesion Kinase and Phosphatidylinositol 3′-Kinase in Integrin Fibronectin Receptor-Mediated, Matrix Metalloproteinase-1–Dependent Invasion by Metastatic Prostate Cancer Cells

alpha(5)beta(1) Integrin interacts with the PHSRN sequence of plasma fibronectin, causing constitutive invasion by human prostate cancer cells. Inhibition of this process reduces tumorigenesis and prevents metastasis and recurrence. In this study, naturally serum-free basement membranes were used as in vitro invasion substrates. Immunoassays were employed to dissect the roles of focal adhesion kinase (FAK), phosphatidylinositol 3'-kinase (PI3K), and protein kinase Cdelta (PKC delta) in alpha(5)beta(1)-mediated, matrix metalloproteinase-1 (MMP-1)-dependent invasion by metastatic human DU 145 prostate cancer cells. We found that a peptide composed of the PHSRN sequence induced rapid FAK phosphorylation at Tyr(397) (Y397), a site whose phosphorylation is associated with kinase activation. The technique of RNA silencing [small interfering RNA (siRNA)] confirmed the role of FAK in PHSRN-induced invasion. PHSRN also induced the association of the p85-regulatory subunit of PI3K with FAK at a time corresponding to FAK phosphorylation and activation, and maximal PI3K activity occurred at this same time. The necessity of PI3K activity in both PHSRN-induced invasion and MMP-1 expression was confirmed by using specific PI3K inhibitors. By employing a specific inhibitor, Rottlerin, and by using siRNA, we also found that PKC delta, a PI3K substrate found in focal adhesions, functions in PHSRN-induced invasion. In addition, the induction of MMP-1 in PHSRN-treated DU 145 cells was shown by immunoblotting, and the role of MMP-1 in PHSRN-induced invasion was confirmed by the use of blocking anti-MMP-1 monoclonal antibody. Finally, a close temporal correspondence was observed between PHSRN-induced invasion and PHSRN-induced MMP-1 activity in DU 145 cells.

Cooperative interactions of HER-2 and HPV-16 oncoproteins in the malignant transformation of human mammary epithelial cells

To better understand the mechanisms of transformation by the oncogene HER-2, we transduced the human mammary epithelial (HME) cell line MCF-10A with HER-2 and developed a cell line that appeared to moderately overexpress HER-2. These MCF-10HER-2 cells were unable to grow in the absence of epidermal growth factor (EGF). However, coexpression of HER-2 with the HPV-16 oncoproteins E6 and E7 resulted in EGF-independent cells that expressed very high levels of constitutively activated HER-2. Interestingly, coexpression of E7 with HER-2 resulted in cells that were EGF-independent for growth but did not express HER-2 to high levels, and coexpression of E6 with HER-2 resulted in cells expressing higher levels of HER-2, which were still dependent on EGF for growth and survival. The MCF-10HER-2E7 and HER-2/E6E7 cells exhibited constitutive activation of a form of epidermal growth factor receptor (EGFR) that had a faster electrophoretic mobility than EGFR activated by exogenous growth factors. Exposure of cells with EGFR activation to ZD1839 (Iressa), at concentrations specific for EGFR, had little or no influence on proliferation of cells with amplified HER-2 but little or no EGFR. These results indicate that HER-2, E6, and E7 cooperate with endogenous EGFR to yield fully transformed cells.

Breast cancer cells with inhibition of p38alpha have decreased MMP-9 activity and exhibit decreased bone metastasis in mice

p38 belongs to a family of mitogen-activated protein kinases, which transfer extracellular signals into intracellular responses. p38 is also frequently detected in clinical breast cancer specimens, but its role as a prognostic factor is not known. Of the various p38 isoforms, p38alpha has been shown to mediate the in vitro invasiveness of breast cancer cells through up-regulation of urokinase plasminogen activator (uPA). We studied the role of p38alpha in breast cancer bone metastases, using dominant negative blockade approach. Human MDA-MB-231 breast cancer clones stably expressing dominant negative p38alpha (p38/AF) exhibited decreased basal MMP-9 activity. TGF-beta1-induced MMP-9 activity was also blunted in these clones, as compared with controls in which TGF-betal up-regulated MMP-9 activity. Consistent with these findings, SB202190, a specific p38 inhibitor, also inhibited TGF-beta1-induced MMP-9 activity in parental cells. The p38/AF clones exhibited also reduced uPA production after growth on vitronectin and decreased cell motility, as compared with controls. VEGF production levels in all the studied clones were similar. The p38/AF clone, which had similar in vitro growth rate as the control pcDNA3 clone, formed significantly less bone metastases in a mouse model, as compared with the control clone. In conclusion, inhibition of the p38alpha pathway results in decreased MMP-9 activity, impaired uPA expression and decreased motility, all of which may contribute to the decreased formation of bone metastasis.

Prediction of lymph node metastasis and perineural invasion of biliary tract cancer by selected features from cDNA array data

OBJECTIVE

To better understand the nature of the malignancy of biliary tract carcinoma and evaluate the feasibility of its prediction by gene expression profiles.

METHODS AND RESULTS

We explored the gene expression profiles characteristic of progression and invasiveness in the cDNA array data obtained from 37 biliary tract carcinomas (15 bile duct, 11 gallbladder, 11 of ampulla of Vater). We pre-selected 51 and 100 genes for the presence versus absence of lymph node metastasis and perineural invasion on the basis of statistical difference. To search optimized sets of genes for prediction, we applied a sequential forward feature selection, minimizing leave-one-out error rates on a k-nearest neighbor classifier. We could predict lymph node metastasis and perineural invasion with an accuracy of 94 and 100%, respectively. When the 6-stage IA cancers without perineural invasion were precluded, a marked difference in gene expression (147 gene), discriminable with 100% accuracy, was noted between positive versus negative perineural invasion, suggesting that the acquisition of invasive character is rather a later molecular pathological event in biliary tract cancer.

CONCLUSION

The present method provides a powerful means of classifying biliary tract carcinomas. We also suggest that perineural invasion is an important target of array databased pattern classification, which may predict patient outcomes and facilitate the determination of the extent of surgery to minimize the risk of recurrence.