Selection of Aptamers Against Vimentin for Isolation and Release of Circulating Tumor Cells Undergoing Epithelial Mesenchymal Transition.

Circulating tumor cells (CTCs) undergoing epithelial mesenchymal transition (EMT) play an essential role in metastasis and have a better correlation with poor disease outcomes, but the most current affinity-based enrichment methods rely on targeting epithelial markers, which are less effective in capturing CTCs undergoing EMT. Herein, we identified and optimized an aptamer (ZY5C) sequence with high binding affinity and specificity against cell surface vimentin (CSV), which is overexpressed on the post-EMT CTCs. Not only can the hairpin-structured ZY5C aptamer specifically recognize a number of cancer cells with native CSV expression, but it can also bind to CSV expressed on EMT-cells. The Kd value of the ZY5C aptamer against CSV-positive T24 cells was found to be 38 ± 4 nM. Using the evolved ZY5C aptamer and multivalent ZY5C aptamer-functionalized chip, we were able to isolate CTCs from the blood of adenocarcinoma, sarcoma, and carcinosarcoma patients. Overall, this ZY5C aptamer and isolation method bring a fresh approach to CTCs analysis, which not only detects CTCs from nonepithelial origin, but also provides an efficient way to in-depth study the role of post-EMT CTCs in clinical application and metastasis mechanisms.

The garlic compound ajoene covalently binds vimentin, disrupts the vimentin network and exerts anti-metastatic activity in cancer cells.

BACKGROUND: Garlic has been used for centuries for its flavour and health promoting properties that include protection against cancer. The vinyl disulfide-sulfoxide ajoene is one of the phytochemicals found in crushed cloves, hypothesised to act by S-thiolating reactive cysteines in target proteins. METHODS: Using our fluorescently labelled ajoene analogue called dansyl-ajoene, ajoene's protein targets in MDA-MB-231 breast cancer cells were tagged and separated by 2D electrophoresis. A predominant band was identified by MALDI-TOF MS/MS to be vimentin. Target validation experiments were performed using pure recombinant vimentin protein. Computational modelling of vimentin bound to ajoene was performed using Schrödinger and pKa calculations by Epik software. Cytotoxicity of ajoene in MDA-MB-231 and HeLa cells was measured by the MTT assay. The vimentin filament network was visualised in ajoene-treated and non-treated cells by immunofluorescence and vimentin protein expression was determined by immunoblot. The invasion and migration activity was measured by wound healing and transwell assays using wildtype cells and cells in which the vimentin protein had been transiently knocked down by siRNA or overexpressed. RESULTS: The dominant protein tagged by dansyl-ajoene was identified to be the 57 kDa protein vimentin. The vimentin target was validated to reveal that ajoene and dansyl-ajoene covalently bind to recombinant vimentin via a disulfide linkage at Cys-328. Computational modelling showed Cys-328 to be exposed at the termini of the vimentin tetramer. Treatment of MDA-MB-231 or HeLa cells with a non-cytotoxic concentration of ajoene caused the vimentin filament network to condense; and to increase vimentin protein expression. Ajoene inhibited the invasion and migration of both cancer cell lines which was found to be dependent on the presence of vimentin. Vimentin overexpression caused cells to become more migratory, an effect that was completely rescued by ajoene. CONCLUSIONS: The garlic-derived phytochemical ajoene targets and covalently modifies vimentin in cancer cells by S-thiolating Cys-328. This interaction results in the disruption of the vimentin filament network and contributes to the anti-metastatic activity of ajoene in cancer cells.

Carcinoma mioepitelial de mama / Myoepithelial carcinoma of the breast

El carcinoma mioepitelial de mama (o mioepitelioma maligno) es un tumor poco frecuente compuesto exclusivamente por células mioepiteliales malignas. Su diagnóstico supone un reto, y viene dado por los hallazgos anatomopatológicos apoyados por las técnicas de inmunohistoquímica. Presentamos un caso clínico y revisión bibliográfica

Myoepithelial carcinoma of the breast (or malignant myoepithelioma) is a rare tumor composed exclusively of malignant myoepithelial cells. Its diagnosis is a challenge and is reached through pathological findings supported by immunohistochemical techniques. We present a case report and a review of the literature

miR-375 Regulates Invasion-Related Proteins Vimentin and L-Plastin.

Invasion is a hallmark of advanced head and neck squamous cell carcinoma (HNSCC). We previously determined that low relative miR-375 expression was associated with poor patient prognosis. HNSCC cells with increased miR-375 expression have lower invasive properties and impaired invadopodium activity. Using stable isotope labeling with amino acids in cell culture and reverse-phase liquid chromatography mass spectrometry, we assessed the impact of miR-375 expression on protein levels in UM-SCC-1 cells. Increased miR-375 expression was associated with down-regulation of proteins involved in cellular assembly and organization, death and survival, and movement. Two invasion-associated proteins, vimentin and L-plastin, were strongly down-regulated by miR-375. Luciferase reporter assays demonstrated that high miR-375 expression reduced vimentin promoter activity, suggesting that vimentin is an indirect target of miR-375. Runt-related transcription factor 1 (RUNX1) is a potential miR-375 direct target, and its knockdown reduced vimentin and L-plastin expression. Data in The Cancer Genome Atlas HNSCC database showed a significant inverse correlation between miR-375 expression and RUNX1, vimentin, and L-plastin RNA expression. These clinical correlations validate our in vitro model findings and support a mechanism in which miR-375 suppresses RUNX1 levels, resulting in reduced vimentin and L-plastin expression. Furthermore, knockdown of RUNX1, L-plastin, and vimentin resulted in significant reductions in cell invasion in vitro, indicating the functional significance of miR-375 regulation of specific proteins involved in HNSCC invasion.

Comparative Label-Free Mass Spectrometric Analysis of Mildly versus Severely Affected mdx Mouse Skeletal Muscles Identifies Annexin, Lamin, and Vimentin as Universal Dystrophic Markers.

The primary deficiency in the membrane cytoskeletal protein dystrophin results in complex changes in dystrophic muscles. In order to compare the degree of secondary alterations in differently affected subtypes of skeletal muscles, we have conducted a global analysis of proteome-wide changes in various dystrophin-deficient muscles. In contrast to the highly degenerative mdx diaphragm muscle, which showed considerable alterations in 35 distinct proteins, the spectrum of mildly to moderately dystrophic skeletal muscles, including interosseus, flexor digitorum brevis, soleus, and extensor digitorum longus muscle, exhibited a smaller number of changed proteins. Compensatory mechanisms and/or cellular variances may be responsible for differing secondary changes in individual mdx muscles. Label-free mass spectrometry established altered expression levels for diaphragm proteins associated with contraction, energy metabolism, the cytoskeleton, the extracellular matrix and the cellular stress response. Comparative immunoblotting verified the differences in the degree of secondary changes in dystrophin-deficient muscles and showed that the up-regulation of molecular chaperones, the compensatory increase in proteins of the intermediate filaments, the fibrosis-related increase in collagen levels and the pathophysiological decrease in calcium binding proteins is more pronounced in mdx diaphragm as compared to the less severely affected mdx leg muscles. Annexin, lamin, and vimentin were identified as universal dystrophic markers.

Cytoskeletal proteins in the follicular wall of normal andcystic ovaries of sows

The expression of cytoskeletal proteins was evaluated immunohistochemically in 36 normal ovaries sampled from 18 sows and 44 cystic ovaries sampled from of 22 sows, was evaluated. All sows had history of reproductive problems, such as infertility or subfertility. The immunohistochemically stained area (IHCSA) was quantified through image analysis to evaluate the expression of these proteins in the follicular wall of secondary, tertiary, and cystic follicles. Cytokeratins (CK) immunoreactivity was strong in the granulosa cell layer (GC) and mild in the theca interna (TI) and externa (TE) of the normal follicles. There was severe reduction of the reaction to CK in the GC in the cystic follicles, mainly in the luteinized cysts. The immunoreactivity for vimentin was higher in the GC from normal and cystic follicles in contrast with the other follicular structures. In the luteinized cysts, the IHCSA for vimentin was significantly higher in TI and in both observed cysts, the labeling was more accentuated in TE. Immunohistochemical detection of desmin and -SMA was restricted to the TE, without differences between the normal and cystic follicles. The results of the current study show that the development of ovarian cysts in sows is associated to changes in the expression of the cytoskeletal proteins CK and vimentin.

A expressão de proteínas do citoesqueleto foi avaliada por imuno-histoquímica em ovários normais e císticos de porcas matrizes. Amostras de 36 ovários normais (18 porcas) e de 44 císticos (22 porcas) foram avaliadas. Todas as matrizes apresentaram histórico de problemas reprodutivos, como infertilidade ou subfertilidade. As áreas coradas por imuno-histoquímica (IHCSA) foram quantificadas por avaliação de imagens avaliando a expressão dessas proteínas na parede folicular de folículos secundários, terciários e císticos. A imuno-reatividade para citoqueratina (CK) foi forte na camada de células da granulosa (GC) e discreta nas tecas interna (TI) e externa (TE) dos folículos normais. Houve redução acentuada da reação de CK na CG dos folículos císticos, principalmente nos cistos luteinizados. A reação para vimentina foi mais intensa na CG dos folículos normais e císticos em comparação com outras estruturas foliculares. Nos cistos luteinizados, a IHCSA para vimentina foi significativamente maior na TI e, em ambos os cistos observados, a marcação foi mais acentuada na TE. A marcação de desmina e actina alfa de músculo liso foi restrita a TE, sem diferenças entre os folículos normais e císticos. Os resultados do presente estudo mostram que o desenvolvimento de cistos ovarianos em porcas matrizes está associado a alterações na expressão das proteínas do citoesqueleto CK e vimentina.

Dermatofibrosarcoma protuberans metastásico: una causa poco frecuente de masa pulmonar / No disponible

El dermatofibrosarcoma protuberans (DFSP) es una neoplasia de partes blandas de malignidad intermedia localizada inicialmente en la piel, desde donde invade tejidos más profundos. Clínicamente se caracteriza por su presentación como un nódulo o placa indurada en tronco o extremidades. El tratamiento inicial es la extirpación quirúrgica local, siendo el factor de mal pronóstico más reconocido una extirpación quirúrgica inadecuada. Hay pocos casos de metástasis descritos en la literatura siendo la localización pulmonar la más frecuente. El estudio inmunohistoquímico se caracteriza por la expresión de vimentina y CD34, y el estudio genético-molecular por la presencia de translocación de cromosomas 17 y 22. El tratamiento de elección es la extirpación quirúrgica completa, seguida de radioterapia y quimioterapia en los casos avanzados. Por tanto, aunque las metástasis son extremadamente raras, la presencia de una masa pulmonar debe incluirse en el diagnóstico diferencial de un paciente con antecedentes de un DFSP

Dermatofibrosarcoma protuberans (DFSP) is a neoplasm of soft tissue of intermediate malignancy, initially localized in the skin developing in the deep layers of skin. Clinically it is characterized by its presentation as a nodule or indurated plaque on the trunk and proximal extremities.Initial treatment is local surgical excision, and an inadequate surgical removal is themayor risk for recurrence. There are few reports of metastases described in the literature; the lung is the most common site of metastasis. Immunohistochemical study is characterized by the expression of vimentin and CD34, and by a reciprocal chromosomal translocation, t(17;22). The treatment is a complete surgical excision, followed by radiotherapy and chemotherapy in advanced cases. Therefore, although metastases are extremely rare, the presence of a lung mass should be included in the differential diagnosis of a patient with a history of DFSP

Isolation and characterization of mesenchymal progenitors derived from the bone marrow of goats native from northeastern Brazil.

PURPOSE: To characterize bone marrow progenitors cells grown in vitro, using native goats from northeastern Brazil as animal model. METHODS: Ten northeastern Brazil native goats of both genders were used from the Piauí Federal University Agricultural Science Center's (UFPI) - Goat Farming Sector. Bone marrow aspirates where taken from the tibial ridge and seeded on culture plates for isolation, expansion and Flow Cytometry (expression markers - Oct-3/4, PCNA, Ck-Pan, Vimentina, Nanog). RESULTS: Progenitor cells showed colonies characterized by the presence of cell pellets with fibroblastoid morphology. Cell confluence was taken after 14 days culture and the non-adherent mononuclear cell progressive reduction. After the first passage, 94.36% cell viability was observed, starting from 4.6 x 106 cell/mL initially seeded. Cells that went through flow cytometry showed positive expression for Oct-3/4, PCNA, Ck-Pan, Vimentina, and Nanog. CONCLUSIONS: Bone marrow progenitor isolated of native goats from northeastern Brazil showed expression markers also seen in embryonic stem cells (Oct-3/4, Nanog), markers of cell proliferation (PCNA) and markers for mesenchymal cells (Vimentina and Ck-pan), which associated to morphological and culture growth features, suggest the existence of a mesenchymal stem cell (MSC) population in the goat bone marrow stromal cells studied.

Isolation and characterization of mesenchymal progenitors derived from the bone marrow of goats native from northeastern Brazil

PURPOSE: To characterize bone marrow progenitors cells grown in vitro, using native goats from northeastern Brazil as animal model. METHODS: Ten northeastern Brazil native goats of both genders were used from the Piauí Federal University Agricultural Science Center's (UFPI) - Goat Farming Sector. Bone marrow aspirates where taken from the tibial ridge and seeded on culture plates for isolation, expansion and Flow Cytometry (expression markers - Oct-3/4, PCNA, Ck-Pan, Vimentina, Nanog). RESULTS: Progenitor cells showed colonies characterized by the presence of cell pellets with fibroblastoid morphology. Cell confluence was taken after 14 days culture and the non-adherent mononuclear cell progressive reduction. After the first passage, 94.36% cell viability was observed, starting from 4.6 x 106 cell/mL initially seeded. Cells that went through flow cytometry showed positive expression for Oct-3/4, PCNA, Ck-Pan, Vimentina, and Nanog. CONCLUSIONS: Bone marrow progenitor isolated of native goats from northeastern Brazil showed expression markers also seen in embryonic stem cells (Oct-3/4, Nanog), markers of cell proliferation (PCNA) and markers for mesenchymal cells (Vimentina and Ck-pan), which associated to morphological and culture growth features, suggest the existence of a mesenchymal stem cell (MSC) population in the goat bone marrow stromal cells studied. .

Self-assembly enhances the strength of fibers made from vimentin intermediate filament proteins.

Hagfish slime threads were recently established as a promising biomimetic model for efforts to produce ecofriendly alternatives to petroleum polymers. Initial attempts to make fibers from solubilized slime thread proteins fell short of achieving the outstanding mechanics of native slime threads. Here we tested the hypothesis that the high strength and toughness of slime threads arise from the ability of constituent intermediate filaments to undergo a stress-induced α-to-ß transition. To do this, we made fibers from human vimentin proteins that were first allowed to self-assemble into 10 nm intermediate filaments. Fibers made from assembled vimentin hydrogels underwent an α-to-ß transition when strained and exhibited improved mechanical performance. Our data demonstrate that it is possible to make materials from intermediate filament hydrogels and that mimicking the secondary structure of native hagfish slime threads using intermediate filament self-assembly is a promising strategy for improving the mechanical performance of biomimetic protein materials.

Discovery of lamin B1 and vimentin as circulating biomarkers for early hepatocellular carcinoma.

The recent advancements in proteomic technologies have reconstituted our research strategies over different type of liver diseases including hepatocellular carcinoma (HCC). Combined analyses on HCC proteome and clinicopathological data of patients have allowed identification of many promising biomarkers that can be further developed into noninvasive diagnostic assays for cancer surveillance. Capitalizing our established proteomic platform primarily based on two-dimensional polyacrylamide gel electrophoresis (2DE) and MALDI-TOF/TOF mass spectrometry, our groups have identified lamin B1 (LMNB1) and vimentin (VIM) as promising biomarkers for detection of early HCC. Protein levels of both biomarkers were significantly elevated in cancerous tissues when compared to the controls in disease-free and cirrhotic liver subjects. Further investigation of the circulating LMNB1 mRNA level in patients' blood samples by standard PCR showed 76% sensitivity and 82% specificity for detection of early HCC. In parallel, an ELISA assay for measuring circulating vimentin level in patients' serum samples could detect small HCC at 40.91% sensitivity and 87.5% specificity. The candidate biomarkers were evaluated with the diagnostic performance of α-fetoprotein (AFP) for HCC. In this article, we address the current protocols for HCC biomarker discovery, ranging from clinical sample preparation, 2DE proteomic profiling and informatics analysis, and assay development and clinical validation study. Focus is emphasized on the methods for sample preservation and low-abundance protein enrichment.

Extragonadal seminoma presenting as a large mass in the pelvic cavity without c-kit-activating mutations.

Extragonadal germ cell tumors are relatively rare tumors, which usually occur in the mediastinum or retroperitoneum. In this report, we present a case of primary seminoma arising in the pelvic cavity. A 58-year-old man with urinary retention and abdominal distension was admitted to our hospital. Computed tomography and magnetic resonance imaging demonstrated a large mass in the pelvic cavity. Histological examination of the specimens obtained by open biopsy revealed seminomatous malignant cells. Immunohistochemical studies detected vimentin, placental alkaline phosphatase and c-kit. Taking these results together with the patient's other clinical manifestations, this case was diagnosed as extragonadal seminoma without c-kit-activating mutations, and chemotherapy followed by radiation therapy was successful. Primary seminoma in the pelvic cavity is extremely rare, but should be considered a cause of pelvic mass formation.

[The role of vimentin during PRRSV infection of Marc-145 cells].

The objective of this study was to investigate the function of vimentin in PRRSV infection. Vimentin gene from Marc-145 cells was amplified by RT-PCR, cloned into pET-28a vector and expressed in Escherichia coli BL21(DE3). The expressed vimentin was confirmed by Western blot and purified which was used to immunize BALB/c mice for the production of antibodies. Vimentin and antibodies were tested for blocking PRRSV infection of Marc-145 cells. The binding of vimentin to PRRSV N and GP5 proteins were tested by the ELISA. The results showed that vimentin gene was amplified successfully and expressed as identified by SDS-PAGE and Western blot. Mouse anti-vimentin antibodies were produced with the titer of 10(5). PRRSV infection of Marc-145 cells was blocked partially by vimentin while blocked completely by the antibobies. In addition, vimentin was bound N protein, but not GP5. These results provide additional information on PRRSV entry into Marc-145 cells.

Japanese encephalitis virus interacts with vimentin to facilitate its entry into porcine kidney cell line.

Japanese encephalitis virus (JEV) requires the presence of an inexplicable cellular receptor on the surface of the host cell for its entry into the cell. The JEV envelope (E) protein has been shown to play an important role in attachment to cells. By using a widely accepted technique, virus overlay protein binding assay (VOPBA), a protein molecule of approximately 60 kDa, identified as vimentin by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI TOF), was recognized on porcine kidney (PS) cells as a possible receptor for JEV. Further, anti-vimentin monoclonal antibodies were able to block JEV entry into the PS cells. Additionally, co-immunoprecipitation assay confirmed that vimentin protein present on the PS cells interacts with the JEV-E protein. These observations indicate that vimentin serves as a putative receptor for JEV in porcine kidney cells.

Vimentin inhibits ATF4-mediated osteocalcin transcription and osteoblast differentiation.

Activating transcription factor 4 (ATF4) is an osteoblast-enriched transcription factor that regulates osteocalcin transcription and osteoblast terminal differentiation. To identify functional partners of ATF4, we applied ROS17/2.8 osteoblast nuclear extracts and purified recombinant His-ATF4 onto a Ni(+) affinity matrix chromatography column. Vimentin was identified by liquid chromatography-mass spectrometry. Coimmunoprecipitation and pulldown assays revealed that vimentin interacted with ATF4 with its first leucine zipper domain. DNA cotransfection and gel retardation demonstrated that vimentin inhibited the transactivation activity of ATF4 on osteocalcin by preventing it to bind OSE1, the ATF4 binding site on the osteocalcin promoter. Northern hybridization revealed that vimentin was expressed at a high level in immature osteoblasts and a low level in fully differentiated osteoblasts. Down-regulation of vimentin by small interfering RNA induced endogenous osteocalcin transcription in immature osteoblasts. Conversely, ectopic overexpression of vimentin in osteoblasts inhibited osteoblast differentiation as shown by lower alkaline phosphatase activity, delayed mineralization, and decreased expression of osteoblast marker genes such as bone sialoprotein and osteocalcin. Together, our data uncover a novel mechanism whereby a cytoskeletal protein, vimentin, acts as a break on differentiation in immature osteoblasts by interacting with ATF4.

Vimentin is required for dengue virus serotype 2 infection but microtubules are not necessary for this process.

The present study investigated the effect of microtubules (MTs) and vimentin during dengue virus serotype 2 (DV2) infection. Immunostaining showed that DV2 infection induced MT and vimentin reorganization. Colocalization of DV2 antigens with MTs or vimentin were often observed in ECV304 cells. MT-disrupting agents could enhance DV2 release but did not affect other steps of virus replication. In contrast, disruption of vimentin inhibited DV2 infection. Our results suggest that an MT-dependent mechanism may not be necessary for DV2 infection, and MT disruption may promote DV2 release. However, vimentin is required for DV2 infection.

Modification of vimentin: a general mechanism of nonenzymatic glycation in human skin.

In a recent study, we were able to show that the intermediate filament protein vimentin aggregates in human dermal fibroblasts because of modification by the advanced glycation endproduct carboxymethyllysine (CML). In this work, we investigated the formation of intracellular CML in relation to the concentration of glucose in the culture medium. The natural degradation product of glucose, methylglyoxal, was able to induce the aggregation of vimentin. This dicarbonyl leads to the formation of the modifications MG-H1 and carboxyethyllysine (CEL) as a result of the reaction with arginine and lysine residues of proteins. Furthermore, we found that the protein vimentin was modified, not only by CML and CEL, but also by pentosidine and pyrraline. These findings underline the special position of vimentin as a preferential target of the Maillard reaction in human skin.

Progesterone receptor or cytoskeletal protein?

Immunoblotting is used to characterize the various nuclear progesterone receptor (nPR) isoforms present in tissues; however, the success of this technique is dependent on the specificity of the primary nPR antibody. The authors investigate the specificity of a frequently used nPR antibody, sc-538, in total protein from human myometrium and a myometrial cell line (PHM1-31). Using immunoblotting, 2 sc-538 immunoreactive bands at 100 and 55 kDa were detected. The bands were extracted and identified by 1-dimensional liquid chromatography mass spectrometry. The predominant protein in the 100-kDa band was alpha-actinin. The dominant proteins in the smaller band were vimentin (57 kDa) and desmin (53 kDa). Myometrial lysate was immunoprecipitated with sc-538, and immunoblotting of the immunoprecipitate with antibodies to alpha-actinin, desmin, and vimentin confirmed the presence of these proteins. The sc-538 nPR antibody therefore cross-reacts with cytoskeletal proteins that could be misinterpreted as nPR isoforms. Such misinterpretation has confused the progesterone response literature.

Generation and expansion of multipotent mesenchymal progenitor cells from cultured human pancreatic islets.

Cellular models and culture conditions for in vitro expansion of insulin-producing cells represent a key element to develop cell therapy for diabetes. Initial evidence that human beta-cells could be expanded after undergoing a reversible epithelial-mesenchymal transition has been recently negated by genetic lineage tracing studies in mice. Here, we report that culturing human pancreatic islets in the presence of serum resulted in the emergence of a population of nestin-positive cells. These proliferating cells were mainly C-peptide negative, although in the first week in culture, proliferating cells, insulin promoter factor-1 (Ipf-1) positive, were observed. Later passages of islet-derived cells were Ipf-1 negative and displayed a mesenchymal phenotype. These human pancreatic islet-derived mesenchymal (hPIDM) cells were expanded up to 10(14) cells and were able to differentiate toward adipocytes, osteocytes and chondrocytes, similarly to mesenchymal stem/precursor cells. Interestingly, however, under serum-free conditions, hPIDM cells lost the mesenchymal phenotype, formed islet-like clusters (ILCs) and were able to produce and secrete insulin. These data suggest that, although these cells are likely to result from preexisting mesenchymal cells rather than beta-cells, hPIDM cells represent a valuable model for further developments toward future replacement therapy in diabetes.

Identification of hydrophobic proteins as biomarker candidates for colorectal cancer.

Nowadays, colorectal cancer is one of the major causes of cancer death in Western countries. Due to the lack of biomarkers with clinical utility for this pathology, and considering that membrane and hydrophobic proteins have not been studied in depth, we performed a prefractionation of colorectal tissues prior to two-dimensional gel electrophoresis in order to identify hydrophobic proteins differentially expressed in colorectal cancer patients. Fractions enriched in hydrophobic proteins were obtained from healthy mucosa and tumor tissue by a specific extraction method based on temperature-dependent phase partitioning with Triton X-114. Proteins were separated by two-dimensional gel electrophoresis and gels were silver-stained, scanned and compared using the PDQuest software. Those spots presenting significantly different abundance were submitted to mass spectrometry for protein identification. Alterations in the expression of cytoskeletal proteins, including a decrease of vimentin and the absence of desmin, were found. We also detected alterations in antioxidant and transport proteins, chaperones, and in two isoforms of the calcium-binding protein S100A6. On the other hand, vimentin was chosen to corroborate the electrophoretic results by specific immunodetection. Most of the altered proteins have been related to cellular membranes, many of them to lipid rafts microdomains in the plasma membrane, and they have also been implicated in the control of cell proliferation, apoptosis, or metastasis. In conclusion, all the proteins found altered in colorectal tumor samples could be considered as candidates for future studies focused on their utility as markers for colorectal diagnosis and prognosis, or as targets for colorectal cancer therapy.