Tumor Cell Budding Research Articles

Decreased miR-320a promotes invasion and metastasis of tumor budding cells in tongue squamous cell carcinoma.

We aimed to determine the specific miRNA profile of tumor budding cells and investigate the potential role of miR-320a in invasion and metastasis of tongue squamous cell carcinoma (TSCC). We collected tumor budding cells and paired central tumor samples from five TSCC specimens with laser capture microdissection and examined the specimens using a miRNA microarray. The specific miRNA signature of tumor budding cells was identified. We found that miR-320a was dramatically decreased in tumor budding cells. Knockdown of miR-320a significantly enhanced migration and invasion of TSCC cell lines. Suz12 was shown to be a direct target of miR-320a. Similar results were also observed in nude mouse models. Multivariate analysis indicated that miR-320a was an independent prognostic factor. Kaplan–Meier analysis demonstrated that decreased miR-320a and high intensity of tumor budding were correlated with poor survival rate, especially in the subgroup with high-intensity tumor budding and low expression of miR-320a. We concluded that decreased expression of miR-320a could promote invasion and metastasis of tumor budding cells by targeting Suz12 in TSCC. A combination of tumor budding and miR-320a may serve as an index to identify an aggressive sub-population of TSCC cells with high metastatic potential.

419 - Expression profiling of tumour budding cells in colorectal cancer suggests an EMT-like phenotype and molecular subtype switching

419 - Expression profiling of tumour budding cells in colorectal cancer suggests an EMT-like phenotype and molecular subtype switching

Tumor budding and laminin5-γ2 in squamous cell carcinoma of the external auditory canal are associated with shorter survival.

Squamous cell carcinoma (SCC) of the external auditory canal (EAC) is rare, usually presents at an advanced stage, and is a more aggressive tumor with poor prognosis. The University of Pittsburgh TNM staging system commonly used in prognostication is not perfect, and more accurate biomarkers predicting prognosis are needed. Tumor budding is an established negative prognostic factor at the invasive front in colorectal cancer. Moreover, immunohistochemical studies showed that laminin 5-γ2 (Ln5-γ2) is expressed at the invasive front in tumor or tumor budding cells. We assessed the prognostic significance of tumor budding and Ln5-γ2 expression by performing Ln5-γ2 immunohistochemistry and evaluated the degree of tumor budding in pre-treatment biopsy specimens, and investigated their correlations to clinicopathological parameters in patients with SCC of the EAC. Patients whose tumors had high budding grade and Ln5-γ2 expression had significantly shorter survival times. Budding grade was significantly correlated with Ln5-γ2 expression. Multivariate analysis revealed that high budding grade predicted poorer prognosis regardless of disease stage. Our results suggested that budding grade and Ln5-γ2 expression can be used as indicators of poor prognosis in patients with SCC of the EAC.

FOSL1 promotes malignant progression of tumor budding cells in tongue squamous cell carcinoma

Background: FOSL1 is a member of the FOS family that is highly expressed in multiple solid cancers. However, the role of FOSL1 is not documented in tumour budding cells of tongue squamous cell carcinoma (TSCC).

Abstract 447: Tumor microenvironment in pancreatic cancer (PDAC): interplay between tumor cells, stromal cells and immune cells

Abstract Introduction: Tumor budding is considered to be the morphologic correlate of epithelial-mesenchymal-transition (EMT) and is an independent prognostic factor in pancreatic ductal adenocarcinoma (PDAC). Here we explore the interactions between tumor budding cells, stromal cells and immune cells in the microenvironment of the tumor buds in PDAC. Methods: Multi-punch tissue-microarrays (TMAs) containing punches from the tumor center and the tumor front, including tumor buds, from a well characterized cohort of 120 PDAC patients, were stained immunohistochemically and by mRNA-in-situ-Hybridization (mRNA-ISH)for the EMT markers E-cadherin, β-catenin, Snail, ZEB1, ZEB2, N-cadherin and Twist and for the immune cell markers CD8, CD4, Foxp3, M1- and M2-macrophages. Expression in budding- and stromal cells and immune-cell counts in the microenvironment of the tumor buds were compared with findings in the main tumor. Results: Tumor buds showed loss of E-cadherin and b-catenin and overexpressed ZEB1 and ZEB2 compared with the neoplastic cells of the main tumor both at protein and mRNA level (p<0.0001 respectively). Stromal cells surrounding tumor buds showed increased protein and mRNA levels of the transcription factors Snail, ZEB1 and ZEB2. The immune microenvironment of the tumor buds composed of numerous Foxp3+cells and M1-macrophages while M2-macrophages were significantly reduced and CD8+cells were almost absent, in contrast to the main tumor. Conclusions: Tumor budding cells show a shift towards EMT-promoting profiles at protein and mRNA level, compared with the neoplastic cells of the main tumor. Stromal cells surrounding tumor buds express high levels of Snail, ZEB1 and ZEB2 suggesting that some stromal cells may represent complete mesenchymally transformed tumor cells or alternatively that there is a special phenotype of cancer associated fibroblasts supporting EMT-Type tumor-budding through cellular crosstalk in the tumor microenvironment of PDAC. Moreover, there is a tumor favoring immune cell composition in the immediate microenvironment of the tumor buds. Our findings suggest a close interaction of the stromal and immune response with the EMT process in PDAC. The combined assessment of host-associated factors such as stromal and immune response and tumor-associated factors such as EMT-type tumor-budding could help us to achieve superior prognostication and patient stratification than either factor alone. Citation Format: Eva Karamitopoulou, Martin Wartenberg, José A. Galván, Inti Zlobec, Alessandro Lugli, Aurel Perren. Tumor microenvironment in pancreatic cancer (PDAC): interplay between tumor cells, stromal cells and immune cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 447. doi:10.1158/1538-7445.AM2015-447

Expression of the hyaluronan-mediated motility receptor RHAMM in tumor budding cells identifies aggressive colorectal cancers

Expression of the hyaluronan-mediated motility receptor (RHAMM, CD168) predicts adverse clinicopathological features and decreased survival for colorectal cancer (CRC) patients. Using full tissue sections, we investigated the expression of RHAMM in tumor budding cells of 103 primary CRCs to characterize the biological processes driving single-cell invasion and early metastatic dissemination. RHAMM expression in tumor buds was analyzed with clinicopathological data, molecular features and survival. Tumor budding cells at the invasive front of CRC expressed RHAMM in 68% of cases. Detection of RHAMM-positive tumor budding cells was significantly associated with poor survival outcome (P = .0312), independent of TNM stage and adjuvant therapy in multivariate analysis (P = .0201). RHAMM-positive tumor buds were associated with frequent lymphatic invasion (P = .0007), higher tumor grade (P = .0296), and nodal metastasis (P = .0364). Importantly, the prognostic impact of RHAMM expression in tumor buds was maintained independently of the number of tumor buds found in an individual case (P = .0246). No impact of KRAS/BRAF mutation, mismatch repair deficiency and CpG island methylation was observed. RHAMM expression identifies an aggressive subpopulation of tumor budding cells and is an independent adverse prognostic factor for CRC patients. These data support ongoing efforts to develop RHAMM as a target for precision therapy.

Heterogeneity analysis of Metastasis Associated in Colon Cancer 1 (MACC1) for survival prognosis of colorectal cancer patients: a retrospective cohort study

BackgroundMetastasis of colorectal cancer (CRC) is directly linked to patient survival. We previously identified the novel gene Metastasis Associated in Colon Cancer 1 (MACC1) in CRC and demonstrated its importance as metastasis inducer and prognostic biomarker. Here, we investigate the geographic expression pattern of MACC1 in colorectal adenocarcinoma and tumor buds in correlation with clinicopathological and molecular features for improvement of survival prognosis.MethodsWe performed geographic MACC1 expression analysis in tumor center, invasive front and tumor buds on whole tissue sections of 187 well-characterized CRCs by immunohistochemistry. MACC1 expression in each geographic zone was analyzed with Mismatch repair (MMR)-status, BRAF/KRAS-mutations and CpG-island methylation.ResultsMACC1 was significantly overexpressed in tumor tissue as compared to normal mucosa (p < 0.001). Within colorectal adenocarcinomas, a significant increase of MACC1 from tumor center to front (p = 0.0012) was detected. MACC1 was highly overexpressed in 55% tumor budding cells. Independent of geographic location, MACC1 predicted advanced pT and pN-stages, high grade tumor budding, venous and lymphatic invasion (p < 0.05). High MACC1 expression at the invasive front was decisive for prediction of metastasis (p = 0.0223) and poor survival (p = 0.0217). The geographic pattern of MACC1 did not correlate with MMR-status, BRAF/KRAS-mutations or CpG-island methylation.ConclusionMACC1 is differentially expressed in CRC. At the invasive front, MACC1 expression predicts best aggressive clinicopathological features, tumor budding, metastasis formation and poor survival outcome.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1150-z) contains supplementary material, which is available to authorized users.

Lack of Association between Membrane-Type 1 Matrix Metalloproteinase Expression and Clinically Relevant Molecular or Morphologic Tumor Characteristics at the Leading Edge of Invasive Colorectal Carcinoma.

Colorectal cancer (CRC) is one of the leading causes of death from cancer in the western world, but tumor biology and clinical course show great interindividual variation. Molecular and morphologic tumor characteristics, such as KRAS/BRAF mutation status, mismatch repair (MMR) protein expression, tumor growth pattern, and tumor cell budding, have been shown to be of key therapeutic and/or prognostic relevance in CRC. Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a membrane-anchored zinc-binding endopeptidase that is expressed at the leading edge of various invasive carcinomas and promotes tumor cell invasion through degradation of the extracellular matrix. The aim of this study was to investigate possible associations between MT1-MMP expression and molecular tumor characteristics as well as morphologic features of tumor aggressiveness in a consecutive series of 79 CRC tissue samples. However, although MT1-MMP was expressed in 41/79 samples (52%), there was no significant association between MT1-MMP expression and KRAS/BRAF mutation status, MMR protein expression, presence of lymphovascular invasion, tumor growth pattern, tumor-infiltrating lymphocytes, or tumor cell budding in our sample cohort (P > 0.05). Thus, we conclude that although MT1-MMP may play a role in CRC invasion, it is not of key relevance to the current models of CRC invasion and aggressiveness.

Tyrosine kinase receptor B (TrkB) expression in colorectal cancers highlights anoikis resistance as a survival mechanism of tumour budding cells.

Tumour buds in colorectal cancer represent an aggressive subgroup of non-proliferating and non-apoptotic tumour cells. We hypothesize that the survival of tumour buds is dependent upon anoikis resistance. The role of tyrosine kinase receptor B (TrkB), a promoter of epithelial-mesenchymal transition and anoikis resistance, in facilitating budding was investigated. Tyrosine kinase receptor B immunohistochemistry was performed on a multiple-punch tissue microarray of 211 colorectal cancer resections. Membranous/cytoplasmic and nuclear expression was evaluated in tumour and buds. Tumour budding was assessed on corresponding whole tissue slides. Relationship to Ki-67 and caspase-3 was investigated. Analysis of Kirsten Ras (KRAS), proto-oncogene B-RAF (BRAF) and cytosine-phosphate-guanosine island methylator phenotype (CIMP) was performed. Membranous/cytoplasmic and nuclear TrkB were strongly, inversely correlated (P<0.0001; r=-0.41). Membranous/cytoplasmic TrkB was overexpressed in buds compared to the main tumour body (P<0.0001), associated with larger tumours (P=0.0236), high-grade budding (P=0.0011) and KRAS mutation (P=0.0008). Nuclear TrkB was absent in buds (P<0.0001) and in high-grade budding cancers (P=0.0073). Among patients with membranous/cytoplasmic TrkB-positive buds, high tumour membranous/cytoplasmic TrkB expression was a significant, independent adverse prognostic factor [P=0.033; 1.79, 95% confidence interval (CI) 1.05-3.05]. Inverse correlations between membranous/cytoplasmic TrkB and Ki-67 (r=-0.41; P<0.0001) and caspase-3 (r=-0.19; P<0.05) were observed. Membranous/cytoplasmic TrkB may promote an epithelial-mesenchymal transition (EMT)-like phenotype with high-grade budding and maintain viability of buds themselves.

Tumor budding in colorectal carcinoma assessed by cytokeratin immunostaining and budding areas: possible involvement of c-Met.

Tumor budding/sprouting has been shown to be an independent adverse prognostic factor in T1 and T3N0 colorectal carcinomas, however, its assessment could be improved by more accurate identification of budding carcinoma cells and consideration of budding areas. Moreover, tumor budding mechanisms are yet to be defined. In this study, we evaluated the identification of budding tumor cells by either H&E staining alone or H&E with immunohistochemistry and developed a scoring system based on budding grades and areas. We examined whether the budding score correlated with clinicopathologic features and prognosis and the association between tumor budding/sprouting and c-Met protein expression and phosphorylation and MET gene copy numbers because c-Met is known to play an important role in colorectal carcinoma tumorigenesis. Cytokeratin immunohistochemistry could identify tumors with shorter disease-free survival (DFS) from the low-grade budding group assessed with H&E alone. High budding scores based on budding grade and area were more significantly correlated with DFS than scores obtained using the budding grade alone. In tumors with a high budding score, c-Met expression and phosphorylation levels and MET gene copy numbers were significantly increased at the invasive front compared with those in superficial tumor portions. This study showed for the first time that high levels of phospho-c-Met at the invasive front were significantly associated with a high budding score and shorter DFS. In conclusion, a budding score assessed by budding grades and budding-positive areas correlates highly with clinicopathologic aggressive features of colorectal carcinoma.

Characterization of cathepsin X in colorectal cancer development and progression

The lysosomal cysteine carboxypeptidase cathepsin X (CTSX), localized predominantly in immune cells, has been associated with the development and progression of cancer. To determine its specific role in colorectal carcinoma (CRC), we analyzed CTSX expression in non-malignant mucosa and carcinoma of 177 patients as well as in 111 adenomas and related it with clinicopathological parameters. Further, the role of CTSX in the adhesion and invasion of the colon carcinoma cell lines HT-29 and HCT116 was investigated in an in vitro culture cell system with fibroblasts and monocytes, reflecting the situation at the tumor invasion front.Epithelial CTSX expression significantly increased from normal mucosa to adenoma and carcinoma, with highest expression levels in high grade intraepithelial neoplasia and in early tumor stages. Loss of CTSX occurred with tumor progression, and correlated with advanced local invasion, lymph node and distal metastasis, lymphatic vessel and vein invasion, tumor cell budding and poorer overall survival of patients with CRC. The subcellular distribution of CTSX changed from vesicular paranuclear expression in the tumor center to submembranous expression in cells of the invasion front. Peritumoral macrophages showed highest expression of CTSX. In vitro assays identified CTSX as relevant factor for cell–cell adhesion and tumor cell anchorage to fibroblasts and basal membrane components, whereas inhibition of CTSX caused increased invasiveness of colon carcinoma cells in mono- and co-culture. In conclusion, CTSX is involved in early tumorigenesis and in the stabilization of tumor cell formation in CRC. The results suggest that loss of CTSX may be needed for tumor cell detachment, local invasion and tumor progression. In addition, CTSX in tumor-associated macrophages indicates a role for CTSX in the anti-tumor immune response.

Association of CD98, integrin β1, integrin β3 and Fak with the progression and liver metastases of colorectal cancer

CD98-mediated β1 and β3 integrins activation can induce Fak phosphorylation which eventually promotes cell survival, proliferation, and migration. We evaluated the expression of CD98, integrin β1, integrin β3 and Fak in 45 cases of matched colorectal cancer (CRC) and liver metastases as well as 35 cases of CRC without liver metastases.There was a gradual increase of the expression of CD98, integrin β1, integrin β3 and Fak as tumor progressed from normal colon to carcinoma to budding tumor cells at the invasive front and to liver metastases. The expression of CD98 and integrin β1 in CRC with liver metastases was significantly higher than that in CRC without liver metastases. Furthermore, for those liver metastases with desmoplastic growth pattern, expression of CD98, integrin β1, integrin β3 and Fak at the metastases center was as strong as that at the metastases periphery. For those liver metastases with pushing or replacement growth patterns, more intense expression of these markers was found at the metastases center than the periphery.Overexpression of CD98, integrin β1, integrin β3 and Fak is associated with the progression and liver metastases of CRC. Overexpression of these markers in liver metastases requires direct contact between tumor cells and the stroma.

The apoptotic and proliferation rate of tumour budding cells in colorectal cancer outlines a heterogeneous population of cells with various impacts on clinical outcome

In colorectal cancer (CRC), tumour buds represent an aggressive cell type at the invasive front with apparently low proliferation. The aim of this study was to determine proliferation and apoptotic rates of buds in comparison to tumour centre, front and mucosa. Whole tissue sections from 188 CRC patients underwent immunohistochemistry for Ki67. Ten high-power fields (HPFs) were evaluated in mucosa, tumour centre, tumour front and tumour buds (total=40 HPFs/case). Caspase-3 and M30 immunohistochemistry were performed on a multipunch tissue microarray from the same cohort. Ki67, caspase-3 and M30 immunoreactivity were correlated with outcome. The average percentage of cells showing Ki67 positivity was 5.2% in mucosa, and was not significantly different between the centre and front of the tumour (38.2% and 34.9%; P<0.0001); 0.3% of buds showed Ki67 positivity (P<0.0001). Caspase-3 expression was similar in mucosa, tumour centre and tumour front, but lower in tumour buds (<0.1%; P<0.0001). M30 staining in buds was decreased (0.01%; P<0.0001) in comparison to other areas. Ki67 positivity in buds was detrimental to survival in univariate (P=0.0352) and multivariate (P=0.0355) analysis. Caspase-3-positive tumours showed better outcome than negative tumours (P=0.0262); but tumours with caspase-3-positive buds showed a worse outcome than those with caspase-3-negative buds (P=0.0235). Ki67, caspase-3 and M30 staining is absent in most tumour buds, suggesting decreased proliferation and apoptosis. However, the fact that Ki67 and caspase-3 immunoreactivity was associated with unfavourable prognosis points to a heterogeneous population of tumour buds.

Tumor budding cells, cancer stem cells and epithelial-mesenchymal transition-type cells in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers with a 5-year survival rate of less than 5%. Moreover, PDAC escapes early detection and resists treatment. Multiple combinations of genetic alterations are known to occur in PDAC including mutational activation of KRAS, inactivation of p16/CDKN2A and SMAD4 (DPC4) and dysregulation of PTEN/PI3K/AKT signaling. Through their interaction with Wingless-INT pathway, the downstream molecules of these pathways have been implicated in the promotion of epithelial–mesenchymal transition (EMT). Emerging evidence has demonstrated that cancer stem cells (CSCs), small populations of which have been identified in PDAC, and EMT-type cells play critical roles in drug resistance, invasion, and metastasis in pancreatic cancer. EMT may be histologically represented by the presence of tumor budding which is described as the occurrence of single tumor cells or small clusters (<5) of dedifferentiated cells at the invasive front of gastrointestinal (including colorectal, oesophageal, gastric, and ampullary) carcinomas and is linked to poor prognosis. Tumor budding has recently been shown to occur frequently in PDAC and to be associated with adverse clinicopathological features and decreased disease-free and overall survival. The aim of this review is to present a short overview on the morphological and molecular aspects that underline the relationship between tumor budding cells, CSCs, and EMT-type cells in PDAC.

Tumor-Infiltrating Immune Cells: Triggers for Tumor Capsule Disruption and Tumor Progression?

Background: Our previous studies of human breast and prostate cancer have shown that aberrant immune cell infiltration is associated with focal tumor capsule disruption and tumor cell budding that facilitate invasion and metastasis. Our current study attempted to determine whether aberrant immune cell infiltration would have similar impact on colorectal cancer (CRC).Materials and Methods: Tissue sections from 100 patients with primary CRC were assessed for the frequencies of focal basement membrane (BM) disruption, muscularis mucosa (MM) fragmentation, and tumor cell dissemination in epithelial structures adjacent and distal to infiltrating lymphoid aggregates using a panel of biomarkers and quantitative digital imaging.Results: Our study revealed: (1) epithelial structures adjacent to lymphoid follicles or aggregates had a significantly higher (p<0.001) frequency of focally disrupted BM, dissociated epithelial cells in the stroma, disseminated epithelial cells within lymphatic ducts or blood vessels, and fragmented MM than their distal counterparts, (2) a majority of dissociated epithelial cells within the stroma or vascular structures were immediately subjacent to or physically associated with infiltrating immune cells, (3) the junctions of pre-invasive and invasive lesions were almost exclusively located at sites adjacent to lymphoid follicles or aggregates, (4) infiltrating immune cells were preferentially associated with epithelial capsules that show distinct degenerative alterations, and (5) infiltrating immune cells appeared to facilitate tumor stem cell proliferation, budding, and dissemination.Conclusions: Aberrant immune cell infiltration may have the same destructive impact on the capsule of all epithelium-derived tumors. This, in turn, may selectively favor the proliferation of tumor stem or progenitor cells overlying these focal disruptions. These proliferating epithelial tumor cells subsequently disseminate from the focal disruption leading to tumor invasion and metastasis.

Prognostic and Diagnostic Significance of Tumor Budding Associated with β-Catenin Expression in Submucosal Invasive Colorectal Carcinoma

Endoscopic resection has become a major curative treatment for early colorectal carcinoma without lymph node metastasis. However, lymph node metastasis, a poor prognostic factor in colorectal carcinoma, occurs in about 10% of the patients with submucosal invasive colorectal carcinoma. Therefore, it is important to identify a high-risk factor for lymph node metastasis in submucosal invasive colorectal carcinoma. This study was designed to identify the relationship between tumor budding with β-catenin expression and lymph node metastasis in submucosal invasive colorectal carcinoma. We investigated the immunohistochemistry of tumor budding in the 142 patients who underwent surgical resection for submucosal invasive colorectal carcinomas between 1984 and 1999 and the expression pattern of β-catenin in budding tumor cells. Accordingly, all the patients were followed up for at least 10 years or until death. Among the 142 patients, lymph node metastasis was detected in 14 patients (9.9%). Univariate analysis showed that tumor budding with ≥ 5 tumor cells or cell clusters with expression of β-catenin in the nucleus was significantly associated with lymph node metastasis (P = 0.005). In contrast, tumor budding detected by hematoxylin and eosin staining was not associated with lymph node metastasis. Multivariate logistic regression analysis showed that tumor budding with ≥ 5 tumor cells or cell clusters with expression of β-catenin in the nucleus was a significant risk factor for lymph node metastasis (odds ratio, 7.124; 95% confidence interval, 1.407-36.062). Thus, tumor budding associated with β-catenin expression is a risk factor for lymph node metastasis in submucosal invasive colorectal carcinoma.

Clinicopathologic factors affecting recurrence after curative surgery for stage I colorectal cancer.

PurposeThe objective of the current study was to identify the clinicopathological risk factors affecting recurrence after a curative resection for stage I colorectal cancer.MethodsWe retrospectively studied 434 patients who underwent a curative resection for stage I colorectal cancer between January 1999 and December 2004. Postoperative oral chemotherapy was performed in 189 patients (45.3%). The following prognostic factors were correlated with recurrence: age, gender, preoperative carcinoembryonic antigen level, location of tumor, T stage, size of tumor, histologic differentiation, growth pattern, and lymphovascular invasion. The median follow-up duration was 65 months.ResultsThe overall recurrence rate was 4.6% (20/434). The median time to recurrence was 33 months. Two-thirds of the recurrence occurred more than two years after surgery. Risk factors associated with recurrence were rectal cancer (P = 0.009), T2 stage (P = 0.010), and infiltrative growth pattern (P = 0.020). A Cox proportional hazards regression analysis demonstrated that the infiltrative growth pattern was an independent predictor for recurrence. Tumor cell budding was observed in all pathologic reviews with recurrence.ConclusionLong-term follow-up is necessary for stage I colorectal patients with high risk factors like rectal cancer, T2 stage, and infiltrative growth pattern.

Tumor cell budding from focally disrupted tumor capsules: a common pathway for all breast cancer subtype derived invasion?

Human breast cancer represents a group of highly heterogeneous lesions consisting of about 20 morphologically and immnohistochemically distinct subtypes with substantially different prognoses. Our recent studies have suggested that all breast cancer subtypes, however, may share a common pathway, tumor cell budding from focally disrupted tumor capsules, for their invasion. The potential mechanisms and clinical implications of our observations are discussed.

Clinicopathologic Significances of EGFR Expression at Invasive Front of Colorectal Cancer

Background : Epidermal growth factor receptor (EGFR) is frequently expressed in the invasive front of colorectal cancer (CRC), but its clinicopathologic significance remains unclear. We investigated the clinical value of the EGFR expression at the invasive front of CRC. Methods : We performed an immunohistochemical analysis in order to examine the expression and distribution of EGFR in 214 cases of CRC. The EGFR status was considered positive when 1% of the tumor cells had membranous staining. Results : Overall, an EGFR expression was observed in 144 (67%) cases and it had no significant relationship with the clinicopathologic parameters. However, an EGFR expression at the invasive front was correlated with lymphatic invasion, lymph node metastasis and a high level of serum carcinoembryonic antigen (p = 0.028, p = 0.043, and p = 0.045, respectively). For the budding-positive CRCs liver metastases were found in the cases with an EGFR expression at the budding, but no liver metastasis occurred in the EGFR negative cases at the budding (p = 0.030). Conclusions : An EGFR expression at the invasive front has clinicopathologic significances in patients with CRC. An EGFR expression at tumor cell budding is a pathologic marker that suggests the high potential for liver metastasis in CRC.

Divergent mechanisms underlie Smad4-mediated positive regulation of the three genes encoding the basement membrane component laminin-332 (laminin-5)

BackgroundFunctional inactivation of the tumor suppressor Smad4 in colorectal and pancreatic carcinogenesis occurs coincident with the transition to invasive growth. Breaking the basement membrane (BM) barrier, a prerequisite for invasive growth, can be due to tumor induced proteolytic tissue remodeling or to reduced synthesis of BM molecules by incipient tumor cells. Laminin-332 (laminin-5), a heterotrimeric BM component composed of α3-, β3- and γ2-chains, has recently been identified as a target structure of Smad4 and represents the first example for expression control of an essential BM component by a tumor and invasion suppressor. Biochemically Smad4 is a transmitter of signals of the TGFβ superfamily of cytokines. We have reported previously, that Smad4 functions as a positive transcriptional regulator of constitutive and of TGFβ-induced transcription of all three genes encoding Laminin-332, LAMA3, LAMB3 and LAMC2.MethodsPromoter-reporter constructs harboring 4 kb upstream regions, each of the three genes encoding Laminin-322 as well as deletion and mutations constructs were established. Promoter activities and TGFβ induction were assayed through transient transfections in Smad4-negative human cancer cells and their stable Smad4-positive derivatives. Functionally relevant binding sites were subsequently confirmed through chromatin immunoprecipitation.ResultsHerein, we report that Smad4 mediates transcriptional regulation through three different mechanisms, namely through Smad4 binding to a functional SBE site exclusively in the LAMA3 promoter, Smad4 binding to AP1 (and Sp1) sites presumably via interaction with AP1 family components and lastly a Smad4 impact on transcription of AP1 factors. Whereas Smad4 is essential for positive regulation of all three genes, the molecular mechanisms are significantly divergent between the LAMA3 promoter as compared to the LAMB3 and LAMC2 promoters.ConclusionWe hypothesize that this divergence in modular regulation of the three promoters may lay the ground for uncoupled regulation of Laminin-332 in Smad4-deficient tumor cells in response to stromally expressed cytokines acting on budding tumor cells.