Altered gene expression in breast cancer liver metastases

Cerebral cavernous malformation proteins, CCM1, CCM2 and CCM3, are decreased in metastatic lesions in a murine breast carcinoma model

Three genes are associated with cerebral cavernous malformations (CCMs): CCM1, CCM2 and CCM3. These genes participate in microvascular angiogenesis, cell-to-cell junctions, migration and apoptosis. We evaluated the expression in vivo of CCM genes in primary tumors and metastastases in a murine model of metastatic breast carcinoma. We used cell lines obtained from metastasis of 4T1, 4TLM and 4THM breast cancer to liver and heart. These cells were injected into the mammary ridge of Balb/C female mice. After 27 days, the primary tumors, liver and lung were removed and CCM proteins were assessed using immunohistochemistry and western blot analysis. CCM proteins were expressed in primary tumor tissues of all tumor-injected animals; however, no CCM protein was expressed in metastatic tumor cells that migrated into other tissues. CCM proteins still were observed in the lung and liver tissue cells. Our findings suggest that CCM proteins are present during primary tumor formation, but when these cells develop metastatic potential, they lose CCM protein expression. CCM protein expression was lost or reduced in metastatic tissues compared to the primary tumor, which indicates that CCM proteins might participate in tumorigenesis and metastasis.

ADAM10 and Neprilysin level decreases in immune cells of mice bearing metastatic breast carcinoma: Possible role in cancer inflammatory response

OBJECTIVE AND DESIGN

ADAM10 and Neprilysin, proteases, play critical role in inflammatory disease, however their role in cancer immune response is not clear. We here evaluated changes in immune response using an experimental model for breast cancer.

MATERIAL AND METHOD

Highly metastatic breast cancer cells (4T1-derived) were injected orthotopically (mammary-pad of Balb-c mice) to induce tumors. Changes in enzyme level and activity as well as alterations in inflammatory cytokine release in the presence or absence of ADAM10 and NEP activity was determined using specific inhibitors and recombinant proteins. Cytokine response was evaluated using mix leucocyte cultures obtained from control and tumor-bearing mice. ANOVA with Dunnett's posttest was used for statistical analysis.

RESULTS

ADAM10 and NEP expression was decreased markedly in lymph nodes and spleens of tumor-bearing mice. ADAM10 activity was reduced together with apparent alterations of ADAM10 processing. ADAM10 and NEP activity decreased TNF-α, IL-6 and IFN-ɣ secretion. Suppression of these inflammatory cytokines were more prominent in cultures obtained from control mice demonstrating counteracting factors that are exist in tumor-bearing mice.

CONCLUSION

Loss of ADAM10 and NEP activity in immune cells during breast cancer metastasis might be one of the main factors involved in induction of chronic inflammation by tumors.

SIRT1/FOXO Signaling Pathway in Breast Cancer Progression and Metastasis

Breast cancer is the second most common cancer in women. The roles of the SIRT and FoxO proteins in tumor progression are known, but their roles in metastasis have not yet been clearly elucidated. In our study, we investigated the roles of SIRT and FoxO proteins their downstream pathways, proteins p21 and p53, in tumor progression and metastasis. We evaluated these proteins in vitro using metastatic 4TLM and 67NR cell lines, as well as their expression levels in tumor-bearing mice. In addition, the regulatory role of SIRT and FoxO proteins in different transduction cascades was examined by IPA core analysis, and clinicopathological evidence was investigated in the TCGA database. In primary tumors, the expression levels of SIRT1, p21, p53, E2F1 and FoxO proteins were higher in 67NR groups. In metastatic tissues, the expression levels of SIRT1, E2F1 and FoxO proteins were found to be enhanced, whereas the levels of p53 and p21 expression were noted to be reduced. IPA analysis also provided empirical evidence of the mechanistic involvement of SIRT and FoxO proteins in tumor progression and metastasis. In conclusion, SIRT1 was found to co-operate with FoxO proteins and to play a critical role in metastasis. Additional research is required to determine why overexpression of SIRT1 in metastatic tissues has oncogenic effects.

Effects of in-vitro modulation of TRPV1 activity on immune response of mice bearing metastatic breast carcinoma: Enhanced inflammatory response may hinder therapeutic potentials of TRPV1 agonists

AIMS

Activation of transient receptor potential vanilloid 1 (TRPV1) ion channels inhibits inflammation, enhance cytotoxic immune response, and may have therapeutic potential in treatment of cancer characterized by increased systemic inflammation. We here determined how activation of TRPV1 alters immune response of tumor-bearing mice.

MAIN METHODS

Three different metastatic subset of 4 T1 breast carcinoma cells were used to induce tumors in Balb-c mice. Mix leukocyte cultures (MLCs) using spleens and draining lymph nodes were prepared and stimulated with various challenges. Effects TRPV1 agonists including capsaicin, antagonist (AMG9810) and Gambogic Amide (GA), a TrkA agonist that sensitizes TRPV1, on secreted levels of cytokines were determined.

KEY FINDINGS

MLCs of tumor-bearing mice secreted markedly higher levels of IL-6 and lower levels of IFN-γ compared to control mice. We observed differential effects of TRPV1 agonists in control and mice bearing different subset of metastatic cells. TRPV1 increased IFN-γ and IL-17 secretion in control mice while they markedly increased IL-6 secretion and suppressed IFN--γ secretion in tumor-bearing mice. Unexpectedly, AMG9810 acted as an inverse agonist and did not antagonize the effects of TRPV1 agonists.

SIGNIFICANCE

Our results demonstrate constitutive activity of TRPV1 in immune cells, suggesting cross activation. To prevent excessive chronic activation of TRPV1 in immune cells in the presence of metastatic breast carcinoma, lower doses of TRPV1 agonist should be considered. Unexpected findings further document that a drug can have multiple intrinsic activities depending on surrounding factors can act on the same receptor as an agonist, antagonist or inverse agonist.

Effects of melatonin and doxorubicin on primary tumor and metastasis in breast cancer model

BACKGROUND

Melatonin exerts oncostatic effects on breast cancer via immunomodulation and anti-oxidation. Doxorubicin is an effective chemotherapeutic agent, but parallel studies also provide ample evidence of an off-target effect of Doxorubicin in breast cancer patients.

OBJECTIVE

Combinatorial use of doxorubicin and melatonin has not been comprehensively analyzed in breast cancer models. We hypothesized that the anti-oxidative, anti-proliferative and anti-inflammatory effects of melatonin could ameliorate the off-target effects of doxorubicin in breast cancer patients and enhance the anti-tumoral effects of doxorubicin. The goal of the study is to test this hypothesis in cancer cell lines and xenografted mice.

METHODS

The effects of Melatonin and doxorubicin on the cell viability were evaluated in 4T1-Brain Metastatic Tumor (4TBM). Furthermore, the effects of melatonin and doxorubicin on the primary tumors and systemic metastasis were evaluated in the xenografted mice. Lung and liver tissues were removed and metastasis analyses were performed. The levels of p65, phospho-STAT3, CD11b+, GR1+, Ki67, and cleaved caspase-3 proteins were determined with immunohistochemistry and western blot analysis. We examined the effects of melatonin and Melatonin+Doxorubicin combination therapy on 4TBM cells.

RESULTS

Our results showed that doxorubicin inhibited the proliferation of metastatic breast cancer cells while melatonin did not affect cells. Tumor growth and metastasis were markedly suppressed in melatonin alone and combination with doxorubicin. The expression of CD11b+ and GR1+ proteins which are indicators of myeloid-derived suppressor cells (MDSCs) were noted to be reduced in both primary tumor and metastatic tissues in melatonin and doxorubicin groups.

CONCLUSION

The combination of melatonin with doxorubicin reduced primary tumor growth and distant metastasis. Based on these results, melatonin is a promising candidate for combinatory use with conventional chemotherapeutics for breast cancer treatment.

Rebound increases in chemokines by CXCR2 antagonist in breast cancer can be prevented by PKCδ and PKCε activators

Activation of CXCR2 by chemokines such as CXCL1 and CXCL2 increases aggressiveness of breast cancer, inducing chemoresistance, hence CXCR2 antagonists are in clinical trials. We previously reported that inhibition of CXCR2 increases MIP-2 (CXCL2), which may inhibit anti-tumoral effects of CXCR2 antagonists. This seems to be due to inhibition of protein kinase C (PKC) by CXCR2 antagonist since specific inhibitor of PKC also enhances MIP-2 secretion. We here examined whether CXCR2 inhibitor also increases KC (CXCL1) secretion, ligand for CXCR2 involved in metastasis and PKC activators can prevent increases in chemokine secretion. We used SB 225002, which is a specific CXCR2 antagonist. The effects of PKC activators that have documented anti-tumoral effects and activates multiple isozymes of PKC such as Ingenol-3-angelate (I3A) and bryostatin-1 were examined here. In addition, FR236924, PKCε selective and 7α-acetoxy-6β-benzoyloxy-12-O-benzoylroyleanone (Roy-Bz), PKCδ selective activators were also tested. The effects of activators were determined using brain metastatic (4TBM) and heart metastatic (4THM) subset of 4T1 breast carcinoma cells because these aggressive carcinoma cells with cancer stem cell features secrete high levels of KC and MIP-2. Inhibition of CXCR-2 activity increased KC (CXCL1) secretion. PKC activators prevented SB225002-induced increases in KC and MIP-2 secretion. Different activators/modulators induce differential changes in basal and SB225002-induced chemokine secretion as well as cell proliferation and the activators that act on PKCδ and/or PKCε such as bryostatin 1, FR236924 and Roy-Bz are the most effective. These activators alone also decrease cell proliferation or chemokine secretion or both. Given the role of KC and MIP-2 in drug resistance including chemotherapeutics, activators of PKCε and PKCδ may prevent emerging of resistance to CXCR2 inhibitors as well as other chemotherapeutics.

The In Vivo Selection Method in Breast Cancer Metastasis

Metastasis is a complex event in cancer progression and causes most deaths from cancer. Repeated transplantation of metastatic cancer cells derived from transplanted murine organs can be used to select the population of highly metastatic cancer cells; this method is called as in vivo selection. The in vivo selection method and highly metastatic cancer cell lines have contributed to reveal the molecular mechanisms of cancer metastasis. Here, we present an overview of the methodology for the in vivo selection method. Recent comparative analysis of the transplantation methods for metastasis have revealed the divergence of metastasis gene signatures. Even cancer cells that metastasize to the same organ show various metastatic cascades and gene expression patterns by changing the transplantation method for the in vivo selection. These findings suggest that the selection of metastasis models for the study of metastasis gene signatures has the potential to influence research results. The study of novel gene signatures that are identified from novel highly metastatic cell lines and patient-derived xenografts (PDXs) will be helpful for understanding the novel mechanisms of metastasis.

NK1R antagonist decreases inflammation and metastasis of breast carcinoma cells metastasized to liver but not to brain; phenotype-dependent therapeutic and toxic consequences

Substance P a neuro-immune mediator acts on Neurokinin-1 and -2 receptors (NK1R and NK2R). Inhibitors of NK1R are considered to be safe and effective approaches for cancer treatment since Aprepitant, a non-peptide antagonist of NK1R is widely used for chemotherapy-induced emesis and has cytotoxic and antitumor effects in various models for cancer. On the other hand, our previous findings demonstrated that systemic inhibition of NK1R may decrease cytotoxic anti-tumoral immune response. Hence, actual consequences of inhibition of neurokinin receptors under in vivo conditions in a syngeneic model of carcinoma should be determined. The effects of highly potent and selective non-peptide mouse NK1R and NK2R antagonists RP 67580 and GR 159897, respectively, on metastatic breast carcinoma were evaluated. Specifically, 4T1 breast cancer cells metastasized to brain (denoted as 4TBM) and liver (denoted as 4TLM) were used to induce tumors in Balb-c mice. Changes in tumor growth, metastasis and immune response to cancer cells were determined. We here observed differential effects of NK1R antagonist depended on the subset of metastatic cells. Specifically, inhibition of NK1R markedly increased liver metastasis of tumors formed by 4TBM but not 4TLM cells. On the contrary, NK1R antagonist decreased inflammatory response and liver metastasis in 4TLM-injected mice. 4TLM tumors act more aggressively inducing more inflammatory response compared to 4TBM tumors. Hence, differential effects of NK1R antagonist are at least partly due to extend and type of the inflammatory response evoked by specific subset metastatic cells. These findings demonstrate the necessity for understanding the immunological consequences of tumor-microenvironment interactions.

HSP90 inhibitor PU-H71 increases radiosensitivity of breast cancer cells metastasized to visceral organs and alters the levels of inflammatory mediators

Heat shock protein 90 (HSP90) inhibitors are considered as new radiosensitizing agents. PU-H71, a novel HSP90 inhibitor, is under evaluation for the treatment of advanced cancer. It is however not known whether PU-H71 alters radiosensitivity of metastatic breast cancer. Hence, we here evaluated mechanisms of possible anti-tumoral and radiosensitizing effects of PU-H71 on breast carcinoma cells metastasized to vital organs such as the liver and brain. The effect of PU-H71 on proliferation of breast carcinoma cells was determined using 4T1 cells and its brain (4TBM), liver (4TLM), and heart (4THM) metastatic subsets as well as non-metastatic 67NR cells. Changes in radiation sensitivity were determined by clonogenic assays. Changes in client proteins and levels of angiogenic and inflammatory mediators from these cancer cell cultures and ex vivo cultures were detected. PU-H71 alone inhibited ERK1/2, p38, and Akt activation and reduced N-cadherin and HER2 which further documented the anti-tumoral effects of PU-H71. The combination of PU-H71 and radiotherapy induced cytotoxic effect than PU-H71 alone, and PU-H71 showed a radiosensitizing effect in vitro. On the other hand, PU-H71 and radiation co-treatment increased p38 phosphorylation which is one of the hallmarks of inflammatory response. Accordingly, IL-6 secretion was increased following PU-H71 and radiotherapy co-treatment ex vivo. Levels of angiogenic and inflammatory factors such as MIP-2, SDF-1, and VEGF were increased under in vitro conditions but not under ex vivo conditions. These results demonstrated for the first time that PU-H71 enhances therapeutic effects of radiotherapy especially in highly metastatic breast carcinoma but a possible increase in inflammatory response should also be considered.

Trained Macrophage Bioreactor for Penetrating Delivery of Fused Antitumor Protein

Macromolecular protein drugs are promising anti-neoplastic agents based on their precise tumor affinity and innocuousness to normal tissues. Although direct delivery of protein drugs remains impractical due to its short half-life in circulation, inefficiency in tumor accumulation, and poor penetrability in intratumoral distribution. Recently, biogenetic cell-based drug vectors have been widely reported for antitumor drug delivery. Macrophage is naturally independent with endogenous proteolysis, elimination of reticuloendothelial system, and immune surveillance. Meanwhile, its innate recruitment behaviors responsive to chronic inflammation signals make it a potential cellular vector for tumor targeting drug delivery. In this study, we develop a trained macrophage bioreactor for tumor homing and an in situ expression of fused antitumor protein. The recombinant tumor necrosis factor related apoptosis-inducing ligand is coded on a plasmid vector with penetrating domain on the C terminus, which improves the intratumoral distribution by facilitating protein dispersion in tumor tissue after in situ secretion. The combination of tumor-infiltrating macrophage bioreactor and multifunctional fused protein drug embodies a new effective tumor homing system for antitumor protein delivery.

A Population-Based Study on Liver Metastases in Women with Newly Diagnosed Breast Cancer

BACKGROUND

Population-based estimates for prognosis among patients with liver metastases in newly diagnosed breast cancer are not generally available.

METHODS

Within the Surveillance, Epidemiology and End Results (SEER) database, we identified 298,370 patients with breast cancer and 4,285 patients diagnosed with initial liver metastases between 2010 and 2014. Data were stratified according to subtype, age, and race. Multivariate logistic and Cox regression were used to identify predictors for the presence of initial liver metastases and prognostic factors, respectively. Kaplan-Meier procedure was used for survival analysis.

RESULTS

A total of 4,285 patients with initial liver metastases (1.4% of the entire cohort, 29.6% of the subset with metastatic disease) were identified. Patients with hormone receptor (HR)-negative human epidermal growth factor receptor 2 (HER2)-positive (4.4% of entire cohort, 52.5% of patients with metastatic disease to any distant site) and HR-positive HER2-positive (2.8% of entire cohort, 40.4% of patients with metastatic disease to any distant site) subtypes had highest incidence proportions. The median survival of patients with liver metastases in the entire cohort was 15.0 months. Patients with HR-positive HER2-positive subtype showed the longest median survival (31.0 months); however, patients with triple-negative subtype showed the shortest median survival (8.0 months).

CONCLUSIONS

Our findings provide population-based estimates of epidemiologic characteristics and prognosis in breast cancer patients diagnosed with initial liver metastases.

IMPACT

This study lends support to the diagnosis of the liver among patients at high risk of liver metastases, including those with HER2-positive and other systemic metastases.

Presence of S100A8/Gr1-Positive Myeloid-Derived Suppressor Cells in Primary Tumors and Visceral Organs Invaded by Breast Carcinoma Cells

BACKGROUND

Increased S100A8/A9 expression in Gr1-positive cells has been shown in myeloid-derived suppressor cells and may play a role in the formation of a metastatic milieu. We aimed to determine S100A8/A9 expression alone and with coexpression of Gr1 (a myeloid marker) in primary tumor and visceral tissues invaded by metastatic breast carcinoma.

MATERIALS AND METHODS

Female BALB/c mice were injected with 4TLM, 4THM, and 67NR orthotopically. Confluent cells (75%-80%) were used. Primary tumor, lung, liver, and spleen tissue samples were removed 26 days after injection. Peripheral blood smears and metastasis assay were performed, as was immunohistochemistry and staining.

RESULTS

S100A8/A9 immunoreactivity alone or coexpressed with Gr1 was found in primary tumors formed by 4TLM and 4THM cells, which was markedly higher than in primary tumors formed by nonmetastatic 67NR cells. Similarly, liver and lung tissues obtained from mice injected with 4TLM or 4THM cells were invaded by S100A8/A9-positive and Gr1-positive cells. Double-positive cells were markedly fewer in liver and lung tissues of animals injected with 67NR cells. S100A8/A9-positive cells were mostly localized in red pulp of spleens. We observed an increased number of neutrophils in the peripheral blood of mice injected with metastatic breast carcinoma cells.

CONCLUSION

Tumor-derived factors may increase S100A8/A9-positive cells locally and systemically, and S100A8/A9-positive cells may provide an appropriate milieu for the formation of metastasis.

CD200fc enhances anti-tumoral immune response and inhibits visceral metastasis of breast carcinoma

CD200 is a widely expressed cell surface glycoprotein that inhibits excessive inflammation in autoimmunity, transplantation, and viral infections. We previously observed that visceral metastasis of highly aggressive and inflammatory 4THM breast carcinoma cells was markedly decreased in CD200 transgenic mice. The goal of this study was to determine whether exogenous exposure to CD200fc mimics the effects of endogenously over expressed CD200. Female BALB/c mice were injected with CD200fc two times a week for five times. Injection was started two days after orthotopic injection of 4THM cells. Tumor infiltrating Gr1+Cd11b+ cells were decreased while CD8+ cells were increased in CD200fc-treated animals. CD200fc injection significantly decreased lung and liver metastasis and the growth of primary tumors. CD200fc injection enhanced the tumor-induced IFN-g response while suppressing the IL-10 response. We observed excessive basal IL-6 secretion in MLC which was significantly decreased in CD200fc treated mice 12 days after injection of 4TM cells. These results are in accord with previous data from CD200 transgenic mice, and demonstrate for the first time that CD200 analogues might have therapeutic potential in the treatment of aggressive breast carcinoma which induces excessive systemic inflammation.

Secretomes reveal several novel proteins as well as TGF-β1 as the top upstream regulator of metastatic process in breast cancer

PURPOSE

Metastatic breast cancer is resistant to many conventional treatments and novel therapeutic targets are needed. We previously isolated subsets of 4T1 murine breast cancer cells which metastasized to liver (4TLM), brain (4TBM), and heart (4THM). Among these cells, 4TLM is the most aggressive one, demonstrating mesenchymal phenotype. Here we compared secreted proteins from 4TLM, 4TBM, and 4THM cells and compared with that of hardly metastatic 67NR cells to detect differentially secreted factors involved in organ-specific metastasis.

METHOD AND RESULTS

Label-free LC-MS/MS proteomic technique was used to detect the differentially secreted proteins. Eighty-five of over 500 secreted proteins were significantly altered in metastatic breast cancer cells. Differential expression of several proteins such as fibulin-4, Bone Morphogenetic Protein 1, TGF-β1 MMP-3, MMP-9, and Thymic Stromal Lymphopoietin were further verified using ELISA or Western blotting. Many of these identified proteins were also present in human metastatic breast carcinomas. Annexin A1 and A5, laminin beta 1, Neutral alpha-glucosidase AB were commonly found at least in three out of six studies examined here. Ingenuity Pathway Analysis showed that proteins differentially secreted from metastatic cells are involved primarily in carcinogenesis and TGF-β1 is the top upstream regulator in all metastatic cells.

CONCLUSIONS

Cells metastasized to different organs displayed significant differences in several of secreted proteins. Proteins differentially altered were fibronectin, insulin-like growth factor-binding protein 7, and Procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1. On the other hand, many exosomal proteins were also common to all metastatic cells, demonstrating involvement of key universal factors in distant metastatic process.

Nephronectin is Decreased in Metastatic Breast Carcinoma and Related to Metastatic Organs

Breast cancer causes death mostly due to distant metastasis. During metastasis, cancer cells create new conditions in which normal tissue structure can be disturbed. Nephronectin, which is the primary ligand for α8β1 integrin, plays an important role in kidney development. There are conflicting findings regarding its role in cancer progression and metastasis, especially in breast carcinoma. The aim of this study was to determine changes in nephronectin expression in primary tumor tissues and metastatic visceral organs, using metastatic and non-metastatic cell lines in a mouse model of breast cancer. In our study, 4T1-Liver Metastatic and 4T1-Heart Metastatic cells, originally derived from 4T1-murine breast carcinoma, and non-metastatic 67NR carcinoma cells were used. Cancer cells were injected orthotopically into the mammary gland of 8-10 week-old Balb-c mice. Primary tumors, lung, liver tissues were collected on 12th and 25th days after the tumor injection. Immunohistochemistry was used to determine expression of nephronectin in tissues. We also investigated the expression levels of the protein by using western blot technique. We found that lung and liver tissue of control animals (not-injected with tumor cells) expressed nephronectin which was lost in animals bearing metastatic tumor for 25 days. In accordance, nephronectin staining of lung and liver was preserved in animals injected with non-metastatic 67NR tumors. These results demonstrate that loss of nephronectin may play an important role in formation metastatic milieu for cancer cells. This is the first study demonstrating that tumor-induced loss of nephronectin expression in visceral organs in which metastatic growth takes place.

Changes in expressions of ADAM9, 10, and 17 as well as α-secretase activity in renal cell carcinoma

BACKGROUND

ADAM9, 10, and 17 are a class of disintegrins and metallproteinases with α-secretase activity. There are conflicting results regarding the role(s) of ADAM9, 10, and 17 in carcinogenesis, and only a few studies have examined their levels and cellular localization in renal cell carcinoma (RCC). Studies examining changes in α-secretase activity in RCC compared to enzymatic activity of the uninvolved kidney are lacking.

METHOD

A cross-sectional study was conducted in 56 patients undergoing radical nephrectomy after the diagnosis of RCC. α-Secretase activity was determined using flourogenic substrate in freshly frozen tumor tissues as well as similarly treated tissues from the neighboring kidney. Immunohistochemical analyses of ADAM9, 10, and 17 were also performed.

RESULTS

α-Secretase activity decreased markedly in all types of RCC as compared to neighboring uninvolved kidney tissue having 5 to 10 times higher levels of α-secretase activity. Although type-dependent variations were observed, tumoral expressions of ADAMs, except for ADAM17, were lower in the tumors compared to that of neighboring tissues, but the changes in α-secretase activity were greater. In RCC tissue, ADAM9 expressions were localized in nuclear and cytoplasmic compartments, whereas ADAM10 and 17 were present predominately in the cytoplasm potentially explaining the markedly decreased enzyme activity. Membranous localization of ADAMs was noted in uninvolved kidney tissue.

CONCLUSIONS

The loss of α-secretase activity observed here in conjunction with previous findings argue against tumorigenic effects of ADAM9, 10, and 17 supporting that increased nuclear and cytoplasmic expression may be an attempt to compensate for loss of function.

Serum-derived exosomes from mice with highly metastatic breast cancer transfer increased metastatic capacity to a poorly metastatic tumor

Altered interaction between CD200 and CD200R represents an example of “checkpoint blockade” disrupting an effective, tumor‐directed, host response in murine breast cancer cells. In CD200R1KO mice, long‐term cure of EMT6 breast cancer, including metastatic spread to lung and liver, was achieved in BALB/c mice. The reverse was observed with 4THM tumors, an aggressive, inflammatory breast cancer, with increased tumor metastasis in CD200R1KO. We explored possible explanations for this difference. We measured the frequency of circulating tumor cells (CTCs) in peripheral blood of tumor bearers, as well as lung/liver and draining lymph nodes. In some cases mice received infusions of exosomes from nontumor controls, or tumor bearers, with/without additional infusions of anticytokine antibodies. The measured frequency of circulating tumor cells (CTCs) in peripheral blood was equivalent in the two models in WT and CD200R1KO mice. Increased metastasis in EMT6 tumor bearers was seen in vivo following adoptive transfer of serum, or serum‐derived exosomes, from 4THM tumor bearers, an effect which was attenuated by anti‐IL‐6, and anti‐IL‐17, but not anti‐TNFα, antibody. Anti‐IL‐6 also attenuated enhanced migration of EMT6 cells in vitro induced by 4THM serum or exosomes, or recombinant IL‐6. Exosome cytokine proteomic profiles responses in 4THM and EMT6 tumor‐bearing mice were regulated by CD200:CD200R interactions, with attenuation of both IL‐6 and IL‐17 in 4THM CD200^tg mice, and enhanced levels in 4THM CD200R1KO mice. We suggest these cytokines act on the microenvironment at sites within the host, and/or directly on tumor cells themselves, to increase metastatic potential.

[High frequency of ancestral allele of the TJP1 polymorphism rs2291166 in Mexican population, conformational effect and applications in surgery and medicine]

BACKGROUND

TJP1 gene encodes a ZO-1 protein that is required for the recruitment of occludins and claudins in tight junction, and is involved in cell polarisation. It has different variations, the frequency of which has been studied in different populations. In Mexico there are no studies of this gene. These are required because their polymorphisms can be used in studies associated with medicine and surgery. Therefore, the aim of this study was to estimate the frequency of alleles and genotypes of rs2291166 gene polymorphism TJP1 in Mexico Mestizos population, and to estimate the conformational effect of an amino acid change.

MATERIAL AND METHODS

A total of 473 individuals were included. The rs2291166 polymorphism was identified PASA PCR-7% PAGE, and stained with silver nitrate. The conformational effect of amino acid change was performed in silico, and was carried out with servers ProtPraram Tool and Search Database with Fasta.

RESULTS

The most frequent allele in the two populations is the ancestral allele (T). A genotype distribution similar to other populations was found. The polymorphism is in Hardy-Weinberg, p>0.05. Changing aspartate to alanine produced a conformational change.

CONCLUSIONS

The study reveals a high frequency of the ancestral allele at rs2291166 polymorphism in the Mexican population.

Activation of neuroimmune pathways increases therapeutic effects of radiotherapy on poorly differentiated breast carcinoma

Recent studies document the importance of neuronal dysfunction in cancer development and metastasis. We reported previously that both depletion of neuropeptides in capsaicin-sensitive sensory nerve endings and vagotomy increases metastasis of triple negative breast carcinoma. Of the sensory neuropeptides, Substance P (SP) is distributed widely for regulation of immune functions. We therefore examined the affects of continuous exposure to low doses of SP on brain metastatic cells of the mouse breast carcinoma (4TBM) in the presence of radiotherapy (RT) thought to increase antigenicity of cancer cells. 4TBM cells have a cancer stem cell phenotype and induce extensive visceral metastasis after orthotopic inoculation into the mammary pad. Results demonstrated that SP treatment decreases the number of tumor-infiltrating myeloid-derived suppressor cells as well as the TNF-α response to LPS challenge. SP also increased CD4+Cd25(bright) cells in draining lymph nodes of tumor-bearing animals and IFN-γ secretion from leukocyte culture prepared from lymph nodes and spleens of tumor-bearing animals. SP also prevented tumor-induced degeneration of sensory nerve endings and altered release of angiogenic factors from cancer-associated fibroblasts (CAF) and tumor explants. In accordance with these observed immunological effects, combination treatment of continuous SP with a single dose of RT induced complete tumor regression and significantly reduced or prevented metastasis in 50% of the animals while suppressing primary tumor growth and metastasis in the remaining mice. These original findings demonstrate that SP through neuroimmune modulation can prevent formation of immune suppression in the tumor microenvironment, enhance cytotoxic immunity in the presence of RT and prevent metastatic growth.

Gene signature model for breast cancer risk prediction for women with sclerosing adenosis

Benign breast disease (BBD) is diagnosed in 1–2 million women/year in the US, and while these patients are known to be at substantially increased risk for subsequent development of breast cancer, existing models for risk assessment perform poorly at the individual level. Here, we describe a DNA-microarray-based transcriptional model for breast cancer risk prediction for patients with sclerosing adenosis (SA), which represent ¼ of all BBD patients. A training set was developed from 86 patients diagnosed with SA, of which 27 subsequently developed cancer within 10 years (cases) and 59 remained cancer-free at 10 years (controls). An diagonal linear discriminate analysis-prediction model for prediction of cancer within 10 years (SA TTC10) was generated from transcriptional profiles of FFPE biopsy-derived RNA. This model was tested on a separate validation case–control set composed of 65 SA patients. The SA TTC10 gene signature model, composed of 35 gene features, achieved a clear and significant separation between case and control with receiver operating characteristic area under the curve of 0.913 in the training set and 0.836 in the validation set. Our results provide the first demonstration that benign breast tissue contains transcriptional alterations that indicate risk of breast cancer development, demonstrating that essential precursor biomarkers of malignancy are present many years prior to cancer development. Furthermore, the SA TTC10 gene signature model, which can be assessed on FFPE biopsies, constitutes a novel prognostic biomarker for patients with SA.

Classifying ten types of major cancers based on reverse phase protein array profiles

Gathering vast data sets of cancer genomes requires more efficient and autonomous procedures to classify cancer types and to discover a few essential genes to distinguish different cancers. Because protein expression is more stable than gene expression, we chose reverse phase protein array (RPPA) data, a powerful and robust antibody-based high-throughput approach for targeted proteomics, to perform our research. In this study, we proposed a computational framework to classify the patient samples into ten major cancer types based on the RPPA data using the SMO (Sequential minimal optimization) method. A careful feature selection procedure was employed to select 23 important proteins from the total of 187 proteins by mRMR (minimum Redundancy Maximum Relevance Feature Selection) and IFS (Incremental Feature Selection) on the training set. By using the 23 proteins, we successfully classified the ten cancer types with an MCC (Matthews Correlation Coefficient) of 0.904 on the training set, evaluated by 10-fold cross-validation, and an MCC of 0.936 on an independent test set. Further analysis of these 23 proteins was performed. Most of these proteins can present the hallmarks of cancer; Chk2, for example, plays an important role in the proliferation of cancer cells. Our analysis of these 23 proteins lends credence to the importance of these genes as indicators of cancer classification. We also believe our methods and findings may shed light on the discoveries of specific biomarkers of different types of cancers.

Mechanisms involved in breast cancer liver metastasis

Liver metastasis is a frequent occurrence in patients with breast cancer; however, the available treatments are limited and ineffective. While liver-specific homing of breast cancer cells is an important feature of metastasis, the formation of liver metastases is not random. Indeed, breast cancer cell factors contribute to the liver microenvironment. Major breakthroughs have been achieved recently in understanding breast cancer liver metastasis (BCLM). The process of liver metastasis consists of multiple steps and involves various factors from breast cancer cells and the liver microenvironment. A further understanding of the roles of breast cancer cells and the liver microenvironment is crucial to guide future work in clinical treatments. In this review we discuss the contribution of breast cancer cells and the liver microenvironment to liver metastasis, with the aim to improve therapeutic efficacy for patients with BCLM.

Upregulation of Claudin-4, CAIX and GLUT-1 in distant breast cancer metastases

BACKGROUND

Several studies have shown that the immunophenotype of distant breast cancer metastases may differ significantly from that of the primary tumor, especially with regard to differences in the level of hormone receptor protein expression, a process known as receptor conversion. This study aimed to compare expression levels of several membrane proteins between primary breast tumors and their corresponding distant metastases in view of their potential applicability for molecular imaging and drug targeting.

METHODS

Expression of Claudin-4, EGFR, CAIX, GLUT-1 and IGF1R was assessed by immunohistochemistry on tissue microarrays composed of 97 paired primary breast tumors and their distant (non-bone) metastases.

RESULTS

In both the primary cancers and the metastases, Claudin-4 was most frequently expressed, followed by GLUT-1, CAIX and EGFR.From primary breast cancers to their distant metastases there was positive to negative conversion, e.g. protein expression in the primary tumor with no expression in its paired metastasis, in 6%, 19%, 12%, 38%, and 0% for Claudin-4 (n.s), GLUT-1 (n.s), CAIX (n.s), EGFR (n.s) and IGF1R (n.s) respectively. Negative to positive conversion was seen in 65%, 47%, 43%, 9% and 0% of cases for Claudin-4 (p = 0.049), GLUT-1 (p = 0.024), CAIX (p = 0.002), EGFR (n.s.) and IGF1R (n.s.) respectively. Negative to positive conversion of Claudin-4 in the metastasis was significantly associated with tumor size (p = 0.015), negative to positive conversion of EGFR with negative PR status (p = 0.046) and high MAI (p = 0.047) and GLUT-1 negative to positive conversion with (neo)adjuvant chemotherapy (p = 0.039) and time to metastasis formation (p = 0.034). CAIX and GLUT-1 expression in the primary tumor were significantly associated with high MAI (p = 0.008 and p = 0.038 respectively).

CONCLUSION

Claudin-4 is frequently expressed in primary breast cancers but especially in their metastases and is thereby an attractive membrane bound molecular imaging and drug target. Conversion in expression of the studied proteins from the primary tumor to metastases was fairly frequent, except for IGF1R, implying that the expression status of metastases cannot always be reliably predicted from the primary tumor, thereby necessitating biopsy for reliable assessment.

Bidirectional effect of CD200 on breast cancer development and metastasis, with ultimate outcome determined by tumor aggressiveness and a cancer-induced inflammatory response

CD200 acts through its receptor (CD200R) to inhibit excessive inflammation. The role of CD200-CD200R1 interaction in tumor immunity is poorly understood. In this study, we examined the role of CD200-CD200R1 interaction in the progression and metastasis of highly aggressive 4THM murine-breast carcinoma using CD200 transgenic (CD200(tg)) and CD200R1 knock-out (CD200R1(-)(/-)) BALB/c mice. 4THM cells induce extensive visceral metastasis and neutrophil infiltration in affected tissues. CD200 overexpression in the host was associated with decreased primary tumor growth and metastasis, whereas lack of CD200R1 expression by host cells was associated with enhanced visceral metastasis. Absence of CD200R1 expression led to decreased tumor-infiltrating-cytotoxic T cells and increased the release of inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin (IL)-6. In contrast, CD200 overexpression led to increased tumor-induced interferon-γ and IL-10 response and decreased TNF-α and IL-6 release. Neutrophil infiltration of tissues was markedly decreased in CD200(tg) animals and increased in CD200R1(-/-) mice. These findings are contradictory to what has been reported in the EMT6 mouse breast-cancer model. Other distinguishing features of tumor elicited by EMT6 and 4THM cell injections were also examined. Visceral tissues from mice bearing EMT6 tumors showed a lack of neutrophil infiltration and decreased IL-6 release in CD200R1(-/-) mice. EMT6 and 4THM cells also differed in vimentin expression and in vitro migration rate, which was markedly lower in EMT6 tumors. These results support the hypothesis that CD200 expression can alter immune responses, and can inhibit metastatic growth of tumor cells that induce systemic and local inflammatory response. Increasing CD200 activity/signaling might be an important therapeutic strategy for treatment of aggressive breast carcinomas.

Claudin-2 is an independent negative prognostic factor in breast cancer and specifically predicts early liver recurrences

BACKGROUND

Predicting any future metastatic site of early-stage breast cancer is important as it significantly influences the prognosis of advanced disease. This study aimed at investigating the potential of claudin-2, over-expressed in breast cancer liver metastases, as a biomarker for predicting liver metastatic propensity in primary breast cancer.

METHODS

Claudin-2 expression was analyzed in two independent cohorts. Cohort 1 included 304 women with metastatic breast cancer diagnosed between 2002 and 2007, while cohort 2 included 237 premenopausal women with early-stage node-negative breast cancer diagnosed between 1991 and 1994. Global transcriptional profiling of fine-needle aspirates from metastases was performed, followed by immunohistochemical analyses in archival primary tumor tissue. Associations between claudin-2 expression and relapse site were assessed by univariable and multivariable Cox regression models including conventional prognostic factors. Two-sided statistical tests were used.

RESULTS

CLDN2 was significantly up-regulated (P < 0.001) in liver metastases compared to other metastatic sites. Claudin-2 protein was more frequently expressed in primary tumors from patients who subsequently developed liver metastases (P = 0.02) and high expression was associated with a shorter metastasis-free interval (cohort 1, HR = 1.4, 95% CI = 1.0-1.9; cohort 2, HR = 2.2, 95% CI = 1.3-3.5). Specifically, a significantly shorter interval between primary tumor diagnosis and liver-specific recurrence was observed among patients with high levels of claudin-2 expression in the primary tumor (cohort 1, HR = 2.3, 95% CI = 1.3-3.9).

CONCLUSION

These results suggest a novel role for claudin-2 as a prognostic biomarker with the ability to predict not only the likelihood of a breast cancer recurrence, but more interestingly, the liver metastatic potential of the primary tumor.

Ductal barriers in mammary epithelium

Tissue barriers play an integral role in the biology and pathobiology of mammary ductal epithelium. In normal breast physiology, tight and adherens junctions undergo dynamic changes in permeability in response to hormonal and other stimuli, while several of their proteins are directly involved in mammary tumorigenesis. This review describes first the structure of mammary ductal epithelial barriers and their role in normal mammary development, examining the cyclical changes in response to puberty, pregnancy, lactation and involution. It then examines the role of adherens and tight junctions and the participation of their constituent proteins in mammary tumorigenic functions such as migration, invasion and metastasis. Finally, it discusses the potential of these adhesion proteins as both prognostic biomarkers and potential therapeutic targets in breast cancer.

Polarity proteins as regulators of cell junction complexes: implications for breast cancer

The epithelium of multicellular organisms possesses a well-defined architecture, referred to as polarity that coordinates the regulation of essential cell features. Polarity proteins are intimately linked to the protein complexes that make the tight, adherens and gap junctions; they contribute to the proper localization and assembly of these cell-cell junctions within cells and consequently to functional tissue organization. The establishment of cell-cell junctions and polarity are both implicated in the regulation of epithelial modifications in normal and cancer situations. Uncovering the mechanisms through which cell-cell junctions and epithelial polarization are established and how their interaction with the microenvironment directs cell and tissue organization has opened new venues for the development of cancer therapies. In this review, we focus on the breast epithelium to highlight how polarity and cell-cell junction proteins interact together in normal and cancerous contexts to regulate major cellular mechanisms such as migration. The impact of these proteins on epigenetic mechanisms responsible for resetting cells toward oncogenesis is discussed in light of increasing evidence that tissue polarity modulates chromatin function. Finally, we give an overview of recent breast cancer therapies that target proteins involved in cell-cell junctions.

DSG3 facilitates cancer cell growth and invasion through the DSG3-plakoglobin-TCF/LEF-Myc/cyclin D1/MMP signaling pathway

Desmoglein 3 (DSG3) is a component of the desmosome, which confers strong cell-cell adhesion. Previously, an oncogenic function of DSG3 has been found in head neck cancer (HNC). Here, we investigated how this molecule contributes to the malignant phenotype. Because DSG3 is associated with plakoglobin, we examined whether these phenotypic alterations were mediated through the plakoglobin molecule. Immunoprecipitation and immunofluorescence staining revealed that DSG3 silencing disrupted its interaction with plakoglobin and induced plakoglobin translocation from the cytoplasm to the nucleus. Knockdown of DSG3 significantly increased the interaction of plakoglobin with the transcriptional factor TCF and suppressed the TCF/LEF transcriptional activity. These effects further conferred to reduced expression of the TCF/LEF downstream target genes, including c-myc, cyclin D1, and MMP-7. Functional analyses showed that DSG3 silencing reduced cell growth and arrested cells at G0/G1 phase. Besides, cell migration and invasion abilities were also decreased. These cellular results were confirmed using tumor xenografts in mice, as DSG3 silencing led to the suppressed tumor growth, plakoglobin translocation and reduced expression of TCF/LEF target genes in tumors. Therefore, our study shows that the desmosomal protein DSG3 additionally functions to regulate malignant phenotypes via nuclear signaling. In conclusion, we found that DSG3 functions as an oncogene and facilitates cancer growth and invasion in HNC cells through the DSG3-plakoglobin-TCF/LEF pathway.

Circulating tumor cells in melanoma patients

Circulating tumor cells (CTCs) are of recognized importance for diagnosis and prognosis of cancer patients. With melanoma, most studies do not show any clear relationship between CTC levels and stage of disease. Here, CTCs were enriched (∼400X) from blood of melanoma patients using a simple centrifugation device (OncoQuick), and 4 melanocyte target RNAs (TYR, MLANA, MITF, and MIF) were quantified using QPCR. Approximately one-third of melanoma patients had elevated MIF and MLANA transcripts (p<0.0001 and p<0.001, respectively) compared with healthy controls. In contrast, healthy controls had uniformly higher levels of TYR and MITF than melanoma patients (p<0.0001). There was a marked shift of leukocytes into the CTC-enriched fractions (a 430% increase in RNA recovery, p<0.001), and no relationship between CTC levels and stage of disease was found. CTCs were captured on microfabricated filters and cultured. Captured melanoma CTCs were large cells, and consisted of 2 subpopulations, based on immunoreactivity. One subpopulation (∼50%) stained for both pan-cytokeratin (KRT) markers and the common leukocyte marker CD-45, whereas the second subpopulation stained for only KRT. Since similar cells are described in many cancers, we also examined blood from colorectal and pancreatic cancer patients. We observed analogous results, with most captured CTCs staining for both CD-45/KRT markers (and for the monocyte differentiation marker CD-14). Our results suggest that immature melanocyte-related cells (expressing TYR and MITF RNA) may circulate in healthy controls, although they are not readily detectable without considerable enrichment. Further, as early-stage melanomas develop, immature melanocyte migration into the blood is somehow curtailed, whereas a significant proportion of patients develop elevated CTC levels (based on MIF and MLANA RNAs). The nature of the captured CTCs is consistent with literature describing leukocyte/macrophage-tumor cell fusion hybrids, and their role in metastatic progression.

Expression of tight junction molecules in breast carcinomas analysed by array PCR and immunohistochemistry

In the past few decades an enormous amount of data became known to clarify the molecular composition and architecture of tight junctions (TJs). Despite the efforts, the expression and function of several TJ genes and proteins in breast carcinoma are still not known and some of the data are contradictory. The expression of forty-four TJ associated genes was examined at mRNA level in eighteen invasive ductal breast carcinoma samples and corresponding normal breast tissues by using low density array PCR. Expressions of claudins (CLDNs) 5, 10, 16, 17, and 18, and ZO-1, ZO-2 were evaluated by immunohistochemistry as well. Using immunohistochemical phenotype as a surrogate for the genetic subtype, 11 luminal A, 3 luminal B, 3 triple negative and one HER2+ cases were included. Ten genes were significantly downregulated in tumors compared with normal breast tissues (CLDNs 5, 10, 16, 18, 19, CTNNAL1, JAM-B, ZO-1, ZO-2 and PARD3), whereas one gene (CLDN17) was significantly up-regulated in tumors when compared with normal breast. At protein level CLDNs 5, 10, 16, 18, ZO-1 and ZO-2 were downregulated in tumors as compared with normal breast tissue. CLDN17 showed variable expression in tumor tissues in comparison to normal breast. In the single HER2+ tumor when compared with the other subtypes CLDNs 5, 16, 17, 18, CTNNAL1, JAM-B, ZO-1, ZO-2 and PARD3 genes were found to be upregulated. We found altered TJ genes and proteins whose expression has not yet been associated with breast carcinoma. Our findings show a tendency of TJ genes and proteins to be downregulated in breast cancer. Further studies are necessary to examine whether the downregulation of the above mentioned TJ associated genes and proteins may contribute to the malignant progression of invasive ductal breast carcinomas.

Claudin-7 is frequently overexpressed in ovarian cancer and promotes invasion

Background

Claudins are tight junction proteins that are involved in tight junction formation and function. Previous studies have shown that claudin-7 is frequently upregulated in epithelial ovarian cancer (EOC) along with claudin-3 and claudin-4. Here, we investigate in detail the expression patterns of claudin-7, as well as its possible functions in EOC.

Methodology/Principal Findings

A total of 95 ovarian tissue samples (7 normal ovarian tissues, 65 serous carcinomas, 11 clear cell carcinomas, 8 endometrioid carcinomas and 4 mucinous carcinomas) were studied for claudin-7 expression. In real-time RT-PCR analysis, the gene for claudin-7, CLDN7, was found to be upregulated in all the tumor tissue samples studied. Similarly, immunohistochemical analysis and western blotting showed that claudin-7 protein was significantly overexpressed in the vast majority of EOCs. Small interfering RNA-mediated knockdown of claudin-7 in ovarian cancer cells led to significant changes in gene expression as measured by microarrays and validated by RT-PCR and immunoblotting. Analyses of the genes differentially expressed revealed that the genes altered in response to claudin-7 knockdown were associated with pathways implicated in various molecular and cellular functions such as cell cycle, cellular growth and proliferation, cell death, development, and cell movement. Through functional experiments in vitro, we found that both migration and invasion were altered in cells where CLDN7 had been knocked down or overexpressed. Interestingly, claudin-7 expression was associated with a net increase in invasion, but also with a decrease in migration.

Conclusion/Significance

Our work shows that claudin-7 is significantly upregulated in EOC and that it may be functionally involved in ovarian carcinoma invasion. CLDN7 may therefore represent potential marker for ovarian cancer detection and a target for therapy.

Hypertonic stress promotes the upregulation and phosphorylation of zonula occludens 1

Tight junction molecules form a barrier between adjacent cells and mediate the cells' ability to develop membranes that constitute boundaries of different compartments within the body. Membranes with selective ion and water passage are important for the electrolyte and water homeostasis in the kidney. Due to their role in the urinary concentration process, renal medullary cells are exposed to hyperosmotic stress. Therefore, we were interested in the question of how mouse inner medullary collecting duct cells (mIMCD3) manage to maintain their cell-cell contacts, despite hypertonicity-induced cell shrinkage. Employing mRNA expression analysis, we found that the zonula occludens type 1 (Zo-1), multi-PDZ domain protein 1 (MUPP1) and cortactin mRNA levels were upregulated in a tonicity-dependent manner. Using Western blot analysis, immunoprecipitation and immunofluorescence, we show that the Zo-1 protein is upregulated, phosphorylated and linked to the actin cytoskeleton in response to hypertonic stress. After cell exposure to hypertonicity, rearrangement of the actin cytoskeleton resulted in a stronger colocalization of actin fibres with Zo-1. Urea, which generates hyperosmolality, but no transcellular gradient, did not induce changes in Zo-1 protein expression or actin rearrangement. This data indicates that Zo-1 is a response protein to inner medullary tonicity and that extracellular stressors can promote Zo-1 protein expression, tyrosine phosphorylation and cytoskeleton association.

Type IV collagen-initiated signals provide survival and growth cues required for liver metastasis

The liver is a major site of metastasis for human malignancies, yet the factors that regulate tumor cell survival and growth in this organ remain elusive. Previously, we reported that M-27(IGF-IR) murine lung carcinoma cells with ectopic insulin-like growth factor-1 (IGF-I) receptor overexpression acquired a site-specific, liver-metastasizing potential. Gene expression profiling and subsequent RNA and protein analyses revealed that this was associated with major changes to the expression of extracellular matrix (ECM) protein-encoding genes including type III, IV and XVIII collagen genes, and these changes were also observed in the respective tumors in vivo. Because type IV collagen was the most prominently altered ECM protein in this model, we further analyzed its functional relevance to liver metastasis. M-27 cells stably overexpressing type IV collagen α1 and α2 chains were generated and their growth and metastatic properties investigated. We found that these cells acquired a site-selective growth advantage in the liver and this was associated with cell rescue from anoikis in a collagen IV/α2 integrin/FAK-dependent manner and increased responsiveness to IGF-I. Conversely, collagen IV or focal adhesion kinase (FAK) silencing by small-interfering RNA in highly metastatic tumor cells enhanced anoikis and decreased liver metastases formation. Moreover, analysis of human surgical specimens revealed uniformly high collagen IV expression in 65/65 hepatic metastases analyzed, regardless of tissue of origin, whereas it was variable and generally low in 50/50 primary colorectal carcinoma specimens examined. The results suggest that collagen IV-conveyed signals are essential cues for liver metastasis in diverse tumor types and identify mediators of collagen IV signaling as potential therapeutic targets in the management of hepatic metastases.

Simple and comprehensive SLA-DQB1 genotyping using genomic PCR and direct sequencing

To enable the efficient analysis of a highly polymorphic swine major histocompatibility complex (MHC) class II gene, swine leukocyte antigen (SLA)-DQB1, we developed a simple and comprehensive high-resolution genotyping protocol. To obtain sufficient sequence information to design a set of common genotyping primers for SLA-DQB1, we cloned SLA-DQB1 introns 1 and 2 from 11 alleles with official four-digit allelic designations and sequenced the regions directly surrounding the SLA-DQB1 exon 2. Significant intronic nucleotide variations, including several deletions, were identified. Based on 733-bp assembled genomic sequences including introns 1 and 2 and exon 2 from 11 different alleles, a primer set was identified that allowed the ubiquitous amplification and analysis of the complete SLA-DQB1 exon 2 sequence. We then developed a method to directly sequence the amplified polymerase chain reaction (PCR) products without further experimental steps. We especially focused on avoiding superimposed peaks, which arose from the presence of allelic deletions, in the sequencing electropherogram of SLA-DQB1 heterozygous animals. The genotyping accuracy was evaluated by comparing the results of genomic sequence-based typing (GSBT) with those of other available methods, including cDNA sequence-based typing (SBT), low-resolution PCR typing with sequence-specific primers, allelic segregation analysis, and heterozygote simulation typing. In all cases, the results were consistent between SLA-DQB1 GSBT and previously reported methods or expected results. We applied it to genotype 350 animals from seven pig breeds. The observed level of heterozygosity from our genotyping was ∼51%, reflecting that a large portion of the animals were inbred miniature pigs. Among the seven pig breeds tested, the allelic diversity of SLA-DQB1 was highest in Berkshire pigs. In conclusion, we have developed a simple and effective SLA-DQB1 GSBT method by combining simple genomic DNA PCR and direct sequencing. Our new method may aid in the study of SLA diversity and disease resistance and susceptibility.

Trefoil factor 3 is oncogenic and mediates anti-estrogen resistance in human mammary carcinoma

We report herein that trefoil factor 3 (TFF3) is oncogenic and mediates anti-estrogen resistance in human mammary carcinoma. Forced expression of TFF3 in mammary carcinoma cells increased cell proliferation and survival, enhanced anchorage-independent growth, and promoted migration and invasion. Moreover, forced expression of TFF3 increased tumor size in xenograft models. Conversely, depletion of endogenous TFF3 with small interfering RNA (siRNA) decreased the oncogenicity and invasiveness of mammary carcinoma cells. Neutralization of secreted TFF3 by antibody promoted apoptosis, decreased cell growth in vitro, and arrested mammary carcinoma xenograft growth. TFF3 expression was significantly correlated to decreased survival of estrogen receptor (ER)-positive breast cancer patients treated with tamoxifen. Forced expression of TFF3 in mammary carcinoma cells increased ER transcriptional activity, promoted estrogen-independent growth, and produced resistance to tamoxifen and fulvestrant in vitro and to tamoxifen in xenograft models. siRNA-mediated depletion or antibody inhibition of TFF3 significantly enhanced the efficacy of antiestrogens. Increased TFF3 expression was observed in tamoxifen-resistant (TAMR) cells and antibody inhibition of TFF3 in TAMR cells improved tamoxifen sensitivity. Functional antagonism of TFF3 therefore warrants consideration as a novel therapeutic strategy for mammary carcinoma.

Presence of tumoural C-reactive protein correlates with progressive prostate cancer

C-reactive protein (CRP) is an acute phase protein implicated in the progression of cancer. A positive correlation between tumour stage and plasma CRP levels was demonstrated in prostate cancer, indicating a relationship between raised CRP levels and more aggressive disease, suggesting a role for inflammatory response in tumour progression. Aim of this study was to assess the tumoural presence and cellular location of CRP and establish if these are linked to clinicopathological features of the cohort and patient survival. Tissue microarray technology was employed to analyse 50 matched pairs of hormone sensitive and refractory prostate cancers. Immunohistochemistry was performed using antibody to CRP. CRP was assessed using the weighted histoscore method. CRP presence was observed in the cytoplasm and nucleus of selected tumours. Cytoplasmic CRP correlated positively with metastases at diagnosis (P=0.039), whereas nuclear CRP presence correlated with metastases at relapse (P=0.006). A trend towards an increase in cytoplasmic and nuclear CRP presence from hormone sensitive to hormone refractory tumours was noticed. No significant association between tumoural CRP presence, time to biochemical relapse or disease-specific survival was observed. Tumoural CRP is likely to have a role in progression of prostate cancer, as it is associated with increased presence of metastases at the time of diagnosis and time of relapse. A larger powered study is necessary to establish if CRP presence is associated with disease-specific survival.

Impact of smoking on the expression of claudins in lung carcinoma

RATIONALE

Tight junctions regulate the paracellular permeability and orientation of cells and claudins are key components of tight junctions.

OBJECTIVES

To study the influence of cigarette smoke on claudin expression in vitro and in lung cancer patients.

METHODS

We studied the effect of smoking on claudin expression by exposing a bronchial cell line (BEAS-2B) and two carcinoma cell lines (SK-LU1 and SK-MES1) to tobacco smoke for 48 h and analysed their claudin mRNA expression. The relation between smoked pack years and protein expression of claudins 1-5 and 7 in 344 lung cancer patients was determined by immunohistochemistry.

MEASUREMENTS AND MAIN RESULTS

In BEAS-2B cells and SK-LU1 cells, an initial increase was followed by a decline in the mRNA expression of several claudins. In SK-MES1 cells, no evident elevation in claudin expression was observed. Intense claudin 1 and 4 positivity was found more often in cancer samples of smokers and ex-smokers compared to non-smokers (p<0.001 and p=0.003, respectively). Heavy smokers with longer than 40 pack-years consumption had more often intense claudin 1 (p=0.011), 4 (p=0.050) or 7 (p=0.058) expression in squamous cell carcinoma compared to non-smokers or smokers with fewer pack-years. Claudin 1 positivity predicted a better survival in adenocarcinoma (p=0.044) and in squamous cell carcinoma (p=0.027) and claudin 4 positivity in adenocarcinoma only (p=0.048). In squamous cell carcinoma, claudin 7 positivity was associated with a better survival (p=0.011).

CONCLUSIONS

Bronchial BEAS-2B cells and SK-LU1 cells respond to tobacco smoke by changing their claudin mRNA synthesis and resulting tight junction permeability changes may thus contribute to tobacco induced carcinogenesis both during initiation and progression. This concept is strengthened by findings in the clinical tumour material, where tobacco consumption was associated with claudin expression.

Claudin-2 is selectively enriched in and promotes the formation of breast cancer liver metastases through engagement of integrin complexes

The liver represents the third most frequent site of metastasis in patients with breast cancer. We performed in vivo selection using 4T1 breast cancer cells to identify genes associated with the liver metastatic phenotype. Coincident with the loss of numerous tight-junctional proteins, we observe claudin-2 overexpression, specifically in liver-aggressive breast cancer cells. We further demonstrate that claudin-2 is both necessary and sufficient for the ability of 4T1 breast cancer cells to colonize and grow in the liver. The liver-aggressive breast cancer cells display a claudin-2-mediated increase in their ability to adhere to extracellular matrix (ECM) components, such as fibronectin and type IV collagen. Claudin-2 facilitates these cell/matrix interactions by increasing the cell surface expression of α(2)β(1)- and α(5)β(1)-integrin complexes in breast cancer cells. Indeed, claudin-2-mediated adhesion to fibronectin and type IV collagen can be blocked with neutralizing antibodies that target α(5)β(1) and α(2)β(1) complexes, respectively. Immunohistochemical analyses reveal that claudin-2, although weakly expressed in primary human breast cancers, is readily detected in all liver metastasis samples examined to date. Together, these results uncover novel roles for claudin-2 in promoting breast cancer adhesion to the ECM and define its importance during breast cancer metastasis to the liver.

Liposome-siRNA-peptide complexes cross the blood-brain barrier and significantly decrease PrP on neuronal cells and PrP in infected cell cultures

Background

Recent advances toward an effective therapy for prion diseases employ RNA interference to suppress PrP^C expression and subsequent prion neuropathology, exploiting the phenomenon that disease severity and progression correlate with host PrP^C expression levels. However, delivery of lentivirus encoding PrP shRNA has demonstrated only modest efficacy in vivo.

Methodology/Principal Findings

Here we describe a new siRNA delivery system incorporating a small peptide that binds siRNA and acetylcholine receptors (AchRs), acting as a molecular messenger for delivery to neurons, and cationic liposomes that protect siRNA-peptide complexes from serum degradation.

Conclusions/Significance

Liposome-siRNA-peptide complexes (LSPCs) delivered PrP siRNA specifically to AchR-expressing cells, suppressed PrP^C expression and eliminated PrP^RES formation in vitro. LSPCs injected intravenously into mice resisted serum degradation and delivered PrP siRNA throughout the brain to AchR and PrP^C-expressing neurons. These data promote LSPCs as effective vehicles for delivery of PrP and other siRNAs specifically to neurons to treat prion and other neuropathological diseases.

A claudin-targeting molecule as an inhibitor of tumor metastasis

Tumor metastasis of epithelium-derived tumors is the major cause of death from malignant tumors. Overexpression of claudin is observed frequently in malignant tumors. However, claudin-targeting antimetastasis therapy has never been investigated. We previously prepared a claudin-4-targeting antitumor molecule that consisted of the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) fused to protein synthesis inhibitory factor (PSIF) derived from Pseudomonas exotoxin. In the present study, we investigated whether claudin CPE receptors can be a target for tumor metastasis by using the C-CPE-fused PSIF as a claudin-targeting agent. One of the most popular murine metastasis models is the lung metastasis of intravenously injected B16 cells. Therefore, we first investigated the effects of the C-CPE-fused PSIF on lung metastasis of claudin-4-expressing B16 (CL4-B16) cells. Intravenous administration of the C-CPE-fused PSIF suppressed lung metastasis of CL4-B16 cells but not B16 cells. Injection of C-CPE-fused PSIF also inhibited tumor growth and spontaneous lung metastasis of murine breast cancer 4T1 cells inoculated into the subcutis. Treatment with C-CPE-fused PSIF did not show apparent side effects in mice. These findings indicate that claudin targeting may be a novel strategy for inhibiting some tumor metastases.

Hepatic tight junctions: From viral entry to cancer metastasis

The tight junction (TJ) is a critical cellular component for maintenance of tissue integrity, cellular interactions and cell-cell communications, and physiologically functions as the “great wall” against external agents and the surrounding hostile environment. During the host-pathogen evolution, viruses somehow found the key to unlock the gate for their entry into cells and to exploit and exhaust the host cells. In the liver, an array of TJ molecules is localized along the bile canaliculi forming the blood-biliary barrier, where they play pivotal roles in paracellular permeability, bile secretion, and cell polarity. In pathology, certain hepatic TJ molecules mediate virus entry causing hepatitis infection; deregulation and functional abnormality of the TJ have also been implicated in triggering liver cancer development and metastasis. All these findings shed new insights on the understanding of hepatic TJs in the development of liver disease and provide new clues for potential intervention.

Vitamin K, an example of triage theory: is micronutrient inadequacy linked to diseases of aging?

The triage theory posits that some functions of micronutrients (the approximately 40 essential vitamins, minerals, fatty acids, and amino acids) are restricted during shortage and that functions required for short-term survival take precedence over those that are less essential. Insidious changes accumulate as a consequence of restriction, which increases the risk of diseases of aging. For 16 known vitamin K-dependent (VKD) proteins, we evaluated the relative lethality of 11 known mouse knockout mutants to categorize essentiality. Results indicate that 5 VKD proteins that are required for coagulation had critical functions (knockouts were embryonic lethal), whereas the knockouts of 5 less critical VKD proteins [osteocalcin, matrix Gla protein (Mgp), growth arrest specific protein 6, transforming growth factor beta-inducible protein (Tgfbi or betaig-h3), and periostin] survived at least through weaning. The VKD gamma-carboxylation of the 5 essential VKD proteins in the liver and the 5 nonessential proteins in nonhepatic tissues sets up a dichotomy that takes advantage of the preferential distribution of dietary vitamin K1 to the liver to preserve coagulation function when vitamin K1 is limiting. Genetic loss of less critical VKD proteins, dietary vitamin K inadequacy, human polymorphisms or mutations, and vitamin K deficiency induced by chronic anticoagulant (warfarin/coumadin) therapy are all linked to age-associated conditions: bone fragility after estrogen loss (osteocalcin) and arterial calcification linked to cardiovascular disease (Mgp). There is increased spontaneous cancer in Tgfbi mouse knockouts, and knockdown of Tgfbi causes mitotic spindle abnormalities. A triage perspective reinforces recommendations of some experts that much of the population and warfarin/coumadin patients may not receive sufficient vitamin K for optimal function of VKD proteins that are important to maintain long-term health.