Metastasis suppressors genes in cancer

Axl mediates tumor invasion and chemosensitivity through PI3K/Akt signaling pathway and is transcriptionally regulated by slug in breast carcinoma

The invasion and chemoresistance are crucial causes of morbidity and relapse for cancer patients. Axl is implicated in the modulation of cell invasion, cancer metastasis, and chemosensitivity in human breast carcinoma cell lines. Both breast cancer cell lines and tissues displayed increased expression of Axl, and it over expressed in highly metastatic breast cancer. The altered expression level of Axl was corresponding to the changed invasive phenotype and chemosensitivity of MDA-MB-231 cells both in vitro and in vivo. Further data indicated that experimental inhibition of Axl by RNAi assay inhibited phosphatidylinositol 3-kinase (PI3K)/Akt/GSK3β signaling pathway, resulted in the decrease of Slug expression, and further suppressed cell invasion properties and chemosensitivity. What is more, after the detection and statistics in human breast cancer specimens, we found the Axl expression was closely correlated with histological grade, lymph node metastasis, and clinical stage (P < 0.01). Taken together, these findings indicate that Axl exerts the role of tumor metastasis and chemosensitivity through activation of the PI3K/Akt/GSK3β signaling pathway, which is transcriptionally regulated by Slug. Our findings support the possibility that Axl is a novel regulator. It means by targeting Axl or its related signaling pathways, we can reduce the invasion and chemosensitivity of breast tumor.

BRMS1 suppresses glioma progression by regulating invasion, migration and adhesion of glioma cells

Breast cancer metastasis suppressor 1 (BRMS1) is a metastasis suppressor gene in several solid tumors. However, the expression and function of BRMS1 in glioma have not been reported. In this study, we investigated whether BRMS1 play a role in glioma pathogenesis. Using the tissue microarray technology, we found that BRMS1 expression is significantly decreased in glioma compared with tumor adjacent normal brain tissue (P<0.01, χ² test) and reduced BRMS1 staining is associated with WHO stages (P<0.05, χ² test). We also found that BRMS1 was significantly downregulated in glioma cell lines compared to normal human astrocytes (P<0.01, χ² test). Furthermore, we demonstrated that BRMS1 overexpression inhibited glioma cell invasion by suppressing uPA, NF-κB, MMP-2 expression and MMP-2 enzyme activity. Moreover, our data showed that overexpression of BRMS1 inhibited glioma cell migration and adhesion capacity compared with the control group through the Src-FAK pathway. Taken together, this study suggested that BRMS1 has a role in glioma development and progression by regulating invasion, migration and adhesion activities of cancer cells.

The metastasis suppressor, N-myc downstream-regulated gene 1 (NDRG1), inhibits stress-induced autophagy in cancer cells

N-myc downstream regulated gene 1 (NDRG1) is a potent metastasis suppressor with an undefined role in the stress response. Autophagy is a pro-survival pathway and can be regulated via the protein kinase-like endoplasmic reticulum kinase (PERK)/eIF2α-mediated endoplasmic reticulum (ER) stress pathway. Hence, we investigated the role of NDRG1 in stress-induced autophagy as a mechanism of inhibiting metastasis via the induction of apoptosis. As thiosemicarbazone chelators induce stress and up-regulate NDRG1 to inhibit metastasis, we studied their effects on the ER stress response and autophagy. This was important to assess, as little is understood regarding the role of the stress induced by iron depletion and its role in autophagy. We observed that the chelator, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), which forms redox-active iron and copper complexes, effectively induced ER stress as shown by activation of the PERK/eIF2α pathway. Dp44mT also increased the expression of the autophagic marker, LC3-II, and this was dependent on activation of the PERK/eIF2α axis, as silencing PERK prevented LC3-II accumulation. The effect of Dp44mT on LC3-II expression was at least partially due to iron-depletion, as this effect was also demonstrated with the classical iron chelator, desferrioxamine (DFO), and was not observed for the DFO-iron complex. NDRG1 overexpression also inhibited basal autophagic initiation and the ER stress-mediated autophagic pathway via suppression of the PERK/eIF2α axis. Moreover, NDRG1-mediated suppression of the pro-survival autophagic pathway probably plays a role in its anti-metastatic effects by inducing apoptosis. In fact, multiple pro-apoptotic markers were increased, whereas anti-apoptotic Bcl-2 was decreased upon NDRG1 overexpression. This study demonstrates the role of NDRG1 as an autophagic inhibitor that is important for understanding its mechanism of action.

Furin is the major proprotein convertase required for KISS1-to-Kisspeptin processing

KISS1 is a broadly functional secreted proprotein that is then processed into small peptides, termed kisspeptins (KP). Since sequence analysis showed cleavage at KR or RR dibasic sites of the nascent protein, it was hypothesized that enzyme(s) belonging to the proprotein convertase family of proteases process KISS1 to generate KP. To this end, cell lines over-expressing KISS1 were treated with the proprotein convertase inhibitors, Dec-RVKR-CMK and α1-PDX, and KISS1 processing was completely inhibited. To identify the specific enzyme(s) responsible for KISS1 processing, mRNA expression was systematically analyzed for six proprotein convertases found in secretory pathways. Consistent expression of the three proteases – furin, PCSK5 and PCSK7 – were potentially implicated in KISS1 processing. However, shRNA-mediated knockdown of furin – but not PCSK5 or PCSK7 – blocked KISS1 processing. Thus, furin appears to be the essential enzyme for the generation of kisspeptins.

Molecular functions of the iron-regulated metastasis suppressor, NDRG1, and its potential as a molecular target for cancer therapy

N-myc down-regulated gene 1 (NDRG1) is a known metastasis suppressor in multiple cancers, being also involved in embryogenesis and development, cell growth and differentiation, lipid biosynthesis and myelination, stress responses and immunity. In addition to its primary role as a metastasis suppressor, NDRG1 can also influence other stages of carcinogenesis, namely angiogenesis and primary tumour growth. NDRG1 is regulated by multiple effectors in normal and neoplastic cells, including N-myc, histone acetylation, hypoxia, cellular iron levels and intracellular calcium. Further, studies have found that NDRG1 is up-regulated in neoplastic cells after treatment with novel iron chelators, which are a promising therapy for effective cancer management. Although the pathways by which NDRG1 exerts its functions in cancers have been documented, the relationship between the molecular structure of this protein and its functions remains unclear. In fact, recent studies suggest that, in certain cancers, NDRG1 is post-translationally modified, possibly by the activity of endogenous trypsins, leading to a subsequent alteration in its metastasis suppressor activity. This review describes the role of this important metastasis suppressor and discusses interesting unresolved issues regarding this protein.

Metastasis tumor-associated protein 2 enhances metastatic behavior and is associated with poor outcomes in estrogen receptor-negative breast cancer

Metastasis remains a major clinical problem in breast cancer. One family of genes previously linked with metastasis is the metastasis tumor-associated (MTA) family, with members MTA1 enhancing and MTA3 inhibiting cancer metastasis. We have previously found that MTA2 enhances anchorage-independent growth in estrogen receptor α (ERα) breast cancers, and, in combination with other genes, performed as a predictive biomarker in ERα-positive breast cancer. We therefore hypothesized that MTA2 enhances breast cancer progression. To test this, cell growth, soft-agar colony formation, migration, and in vivo metastasis were examined in MTA2-overexpressing and Vector control transfected ERα-negative breast cancer cells. Pathways regulating cell-cell interaction, adhesion, and signaling through the Rho pathway were also investigated. Effects of the inhibition of the Rho pathway using a Rho Kinase inhibitor were assessed in soft-agar colony formation and motility assays in MTA2-overexpressing cells. MTA2 expression was associated with poor prognostic markers, and levels of MTA2 were associated with increased risk of early recurrence in retrospective analyses. MTA2 overexpression was associated with enhanced metastasis, and pathways regulating cell-cell interactions in vitro and in vivo. Most critically, MTA2-enhanced motility could be blocked by inhibiting Rho pathway signaling. We present the novel finding that MTA2 defined a subset of ERα-negative patients with a particularly poor outcome.

Starfish polysaccharides downregulate metastatic activity through the MAPK signaling pathway in MCF-7 human breast cancer cells

We investigated the effects of starfish (Asterina pectinifera) polysaccharides on metastatic activity in MCF-7 estrogen receptor (ER)-positive human breast cancer cells. In wound healing assay, 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cell migration was dose-dependently decreased by the starfish polysaccharides (PS). Transcription of aromatase, which catalyzes estrogen synthesis from androgen, was reduced by PS. Also, transcription of TPA-induced cyclooxygenase-2 (COX-2), which enhances breast cancer progression and metastasis via the increase of prostaglandin E2 biosynthesis, was downregulated by the PS in a dose-dependent manner. PS decreased the expression and activity of matrix metalloproteinase (MMP)-9, an important factor in the degradation of basement membrane and extracellular matrix in the metastasis process. In contrast, mRNA expression of tissue inhibitor of matrix metalloproteinase (TIMP)-1, a MMP inhibitor, was increased by 10-120 μg/ml of PS but not that of TIMP-2. We also found that PS reversed the phosphorylations of p38, ERK and JNK but not IκBα and NF-κB. These results demonstrate that PS successfully inhibits PKC-mediated cell migration and metastatic activities in MCF-7 ER-positive human breast cancer cells via downregulation of MMP-9 activity mediated by TIMP-1 upregulation and inhibition of aromatase and COX-2 expression. Also, COX-2 and MMP-9 expressions are attenuated through the inhibition of AP-1 transcription activity via the downregulation of c-Jun expression regulated by p38, ERK and JNK signaling. In conclusion, the present investigation shows that PS may prevent COX-2- and MMP-9-mediated metastatic activities in MCF-7 ER-positive breast cancer cells through the downregulation of MAPK signaling pathways.

Loss of the metastasis suppressor gene KiSS1 is associated with lymph node metastasis and poor prognosis in human colorectal cancer

Cancer research is currently focused on blocking the metastatic process at its early steps. Some particularly attractive targets are metastasis suppressor genes, which control cancer cell dissemination. The aim of this study was to clarify the relationship between the expression of KiSS1, a metastasis suppressor gene, and disease progression in colorectal cancer patients. One-hundred and seventy-five patients who underwent surgery for colorectal cancer were enrolled in this study. We analyzed KiSS1 mRNA expression by real-time reverse transcription PCR in colorectal cancer tissue and paired adjacent normal mucosa. KiSS1 protein expression in early- and advanced-stage colorectal cancer samples was determined by immunohistochemical analysis. Decreased KiSS1 expression was significantly associated with lymph node metastasis and was an independent prognostic factor. Logistic regression analysis revealed that decreased KiSS1 expression was an independent risk factor for lymph node metastasis. Immunohistochemical analysis indicated that KiSS1 was highly expressed in the cell cytoplasm of early-stage colorectal cancer cells. The loss of KiSS1 appears to correlate with the progression of lymph node metastasis. An assessment of KiSS1 expression may assist in the accurate colorectal cancer diagnosis and may contribute to predict clinical outcomes.

Diet, nutrients, phytochemicals, and cancer metastasis suppressor genes

The major factor in the morbidity and mortality of cancer patients is metastasis. There exists a relative lack of specific therapeutic approaches to control metastasis, and this is a fruitful area for investigation. A healthy diet and lifestyle not only can inhibit tumorigenesis but also can have a major impact on cancer progression and survival. Many chemicals found in edible plants are known to inhibit metastatic progression of cancer. While the mechanisms underlying antimetastatic activity of some phytochemicals are being delineated, the impact of diet, dietary components, and various phytochemicals on metastasis suppressor genes is underexplored. Epigenetic regulation of metastasis suppressor genes promises to be a potentially important mechanism by which dietary components can impact cancer metastasis since many dietary constituents are known to modulate gene expression. The review addresses this area of research as well as the current state of knowledge regarding the impact of diet, dietary components, and phytochemicals on metastasis suppressor genes.

Case-only analyses of the associations between polymorphisms in the metastasis-modifying genes BRMS1 and SIPA1 and breast tumor characteristics, lymph node metastasis, and survival

Lymph node metastases and tumor characteristics predict breast cancer prognosis but correlate imperfectly with likelihood of metastatic relapse. Discovery of genetic polymorphisms affecting metastasis may improve identification of patients requiring aggressive adjuvant therapy to prevent recurrence. We investigated associations between several variants in the BRMS1 and SIPA1 metastasis-modifying genes and lymph node metastases, tumor subtype and grade, recurrence, disease-free survival, and overall survival. This cross-sectional and prospective prognostic analysis included 859 patients who received surgery for incident breast cancer at Roswell Park Cancer Institute, participated in the DataBank and BioRepository shared resource, and had DNA, clinical, and pathology data available for analysis. Genotyping for BRMS1 (rs11537993, rs3116068, and rs1052566) and SIPA1 (rs75894763, rs746429, rs3741378, and rs2306364) polymorphisms was performed using Sequenom(®) iPLEX Gold and Taqman(®) real-time PCR assays. Logistic and Cox proportional hazards regressions were used to estimate odds ratios (OR) and hazard ratios (HR), respectively. BRMS1 rs1052566 heterozygous individuals were more likely to have node-positive tumors (OR = 1.58, 95 % CI 1.13-2.23), although there was no dose-response relationship, and those with at least one variant allele were less likely to have the luminal B subtype (AG + AA: OR = 0.59, 95 % CI 0.36-0.98). BRMS1 rs3116068 was associated with increased likelihood of having the luminal B and the HER2-enriched tumor subtype (P trend = 0.03). Two SIPA1 SNPs, rs746429 and rs2306364, were associated with decreased risk of triple-negative tumors (P trend = 0.04 and 0.07, respectively). Presence of 8 or more risk alleles was associated with an increased likelihood of having a node-positive tumor (OR = 2.14, 95 % CI 1.18-3.36, P trend = 0.002). There were no significant associations with survival. Polymorphisms in metastasis-associated genes may be related to tumor characteristics and lymph node metastasis, but not survival. Future evaluation of metastasis-modifying gene variants is necessary to better understand the biology of metastasis.

Epigenetic regulation and role of metastasis suppressor genes in pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is distinguished by rapid dissemination. Thus, genetic and/or epigenetic deregulation of metastasis suppressor genes (MSG) is a likely event during early pancreatic carcinogenesis and a potential diagnostic marker for the disease. We investigated 9 known MSGs for their role in the dissemination of PDAC and examined their promoters for methylation and its use in PDAC detection.

METHODS

MRNA expression of 9 MSGs was determined in 18 PDAC cell lines by quantitative RT-PCR and promoter methylation was analyzed by Methylation Specific PCR and validated by Bisulfite Sequencing PCR. These data were compared to the cell lines' in vivo metastatic and invasive potential that had been previously established. Statistical analysis was performed with SPSS 20 using 2-tailed Spearman's correlation with P < 0.05 being considered significant.

RESULTS

Complete downregulation of MSG-mRNA expression in PDAC cell lines vs. normal pancreatic RNA occurred in only 1 of 9 investigated genes. 3 MSGs (CDH1, TIMP3 and KiSS-1) were significantly methylated. Methylation only correlated to loss of mRNA expression in CDH1 (P < 0.05). Bisulfite Sequencing PCR showed distinct methylation patterns, termed constant and variable methylation, which could distinguish methylation-regulated from non methylation-regulated genes. Higher MSG mRNA-expression did not correlate to less aggressive PDAC-phenotypes (P > 0.14).

CONCLUSIONS

Genes with metastasis suppressing functions in other tumor entities did not show evidence of assuming the same role in PDAC. Inactivation of MSGs by promoter methylation was an infrequent event and unsuitable as a diagnostic marker of PDAC. A distinct methylation pattern was identified, that resulted in reduced mRNA expression in all cases. Thus, constant methylation patterns could predict regulatory significance of a promoter's methylation prior to expression analysis and hence present an additional tool during target gene selection.

The ubiquitin-CXCR4 axis plays an important role in acute lung infection-enhanced lung tumor metastasis

PURPOSE

Our goals were to test the effect of acute lung infection on tumor metastasis and to investigate the underlying mechanisms.

EXPERIMENTAL DESIGN

We combined bacteria-induced and lipopolysaccharide (LPS)-induced acute lung injury/inflammation (ALI) mouse models with mouse metastatic models to study the effect of acute inflammation on lung metastasis in mice. The mechanisms were investigated in ex vivo, in vitro, and in vivo studies.

RESULTS

Both bacteria- and LPS-induced ALI significantly enhanced lung metastasis of four tail vein-injected mouse tumor cell lines. Bacteria also enhanced lung metastasis when 4T1 cells were orthotopically injected. The bronchoalveolar lavage fluid (BALF) from LPS- or bacteria-injected mice stimulated migration of tumor cells. In vivo tracking of metastatic RM-9 cells showed that bacterial injection enhanced early dissemination of tumor cells to the lung. The majority of the BALF migratory activity could be blocked by AMD3100, a chemokine receptor 4 (CXCR4) inhibitor. All tested cell lines expressed CXCR4. The levels of extracellular ubiquitin, but not stromal cell-derived factor-1, in BALF were significantly increased by LPS. Ubiquitin was able to induce AMD3100-sensitive migration of tumor cells. Finally, the antibacterial agent amoxicillin and the CXCR4 inhibitor AMD3100 blocked the enhancement effect of bacterial infection on tumor metastasis.

CONCLUSIONS

Acute lung infection dramatically increased cancer cell homing to the lung and lung metastasis. This change may be due to an alteration of the lung microenvironment and preparation of a favorable metastatic "niche." This effect was seen in multiple cancer types and thus may have broad applications for cancer patients in prevention and/or treatment of metastasis.

Cloning and characterization of a novel human BRMS1 transcript variant in hepatocellular carcinoma cells

Breast cancer metastasis suppressor 1 (BRMS1) is able to suppress tumor metastasis without affecting primary tumor growth in various cancers. Here, we report a novel transcript variant of human BRMS1, termed BRMS1.vh. BRMS1.vh is identical to the major BRMS1 variant (BRMS1.v1) except for missing base pairs 683-775, encoding a 215-amino acid protein lacking a functional nuclear localization sequence. Expression of BRMS1.vh in hepatocellular carcinoma (HCC) cells suppressed NF-κB signaling pathway, sensitized cells to apoptotic stimuli, leading to suppressed tumor growth. Taken together, our results suggest a potential role for BRMS1.vh in regulating cell apoptosis and tumor growth in HCC.

Targeting tumor metastasis by regulating Nm23 gene expression

The Nm23 gene is a metastatic suppressor identified in a melanoma cell line and expressed in different tumors where their levels of expression are associated with reduced or increased metastatic potential. Nm23 is one of the over 20 metastasis suppressor genes (MSGs) confirmed in vivo. It is highly conserved from yeast to human, implying a critical developmental function. Tumors with alteration of the p53 gene and reduced expression of the Nm23 gene are more prone to metastasis. Nm23-H1 has 3'-5' exonuclease activity. This review focuses on the role of Nm23 in cancer progression and also a potential novel target for cancer therapy.

ATF3 suppresses metastasis of bladder cancer by regulating gelsolin-mediated remodeling of the actin cytoskeleton

Bladder cancer is associated with high recurrence and mortality rates due to metastasis. The elucidation of metastasis suppressors may offer therapeutic opportunities if their mechanisms of action can be elucidated and tractably exploited. In this study, we investigated the clinical and functional significance of the transcription factor activating transcription factor 3 (ATF3) in bladder cancer metastasis. Gene expression analysis revealed that decreased ATF3 was associated with bladder cancer progression and reduced survival of patients with bladder cancer. Correspondingly, ATF3 overexpression in highly metastatic bladder cancer cells decreased migration in vitro and experimental metastasis in vivo. Conversely, ATF3 silencing increased the migration of bladder cancer cells with limited metastatic capability in the absence of any effect on proliferation. In keeping with their increased motility, metastatic bladder cancer cells had increased numbers of actin filaments. Moreover, ATF3 expression correlated with expression of the actin filament severing protein gelsolin (GSN). Mechanistic studies revealed that ATF3 upregulated GSN, whereas ATF3 silencing reduced GSN levels, concomitant with alterations in the actin cytoskeleton. We identified six ATF3 regulatory elements in the first intron of the GSN gene confirmed by chromatin immunoprecipitation analysis. Critically, GSN expression reversed the metastatic capacity of bladder cancer cells with diminished levels of ATF3. Taken together, our results indicate that ATF3 suppresses metastasis of bladder cancer cells, at least in part through the upregulation of GSN-mediated actin remodeling. These findings suggest ATF3 coupled with GSN as prognostic markers for bladder cancer metastasis.

Silencing of diphthamide synthesis 3 (Dph3) reduces metastasis of murine melanoma

Melanoma is the most dangerous skin cancer due to its highly metastatic potential and resistance to chemotherapy. Currently, there is no effective treatment for melanoma once it is progressed to metastatic stage. Therefore, further study to elucidate the molecular mechanism underlying the metastasis of melanoma cells is urgently required for the improvement of melanoma treatment. In the present study, we found that diphthamide synthesis 3 (Dph3) is involved in the metastasis of B16F10 murine melanoma cells by insertional mutagenesis. We demonstrated that Dph3 disruption impairs the migration of B16F10 murine melanoma cells. The requirement of Dph3 in the migration of melanoma cells was further confirmed by gene silencing with siRNA in vitro. In corresponding to this result, overexpression of Dph3 significantly promoted the migratory ability of B16F10 and B16F0 melanoma cells. Moreover, down regulation of Dph3 expression in B16F10 melanoma cells strikingly inhibits their cellular invasion and metastasis in vivo. Finally, we found that Dph3 promotes melanoma migration and invasion through the AKT signaling pathway. To conclude, our findings suggest a novel mechanism underlying the metastasis of melanoma cells which might serve as a new intervention target for the treatment of melanoma.

Inhibition of metastatic lung cancer in C57BL/6 mice by liposome encapsulated all trans retinoic acid (ATRA)

The purpose of this study was to investigate whether all trans retinoic acid (ATRA) incorporated in liposome composed of distearoylphosphatidylcholine (DSPC/cholesterol) could inhibit the metastatic lung cancer in mice more efficiently than free ATRA. Metastatic lung cancer model was developed by intravenous injection of B16F10 cells and it is also referred as melanoma model. In this present study, C57BL/6 mice were divided into several groups as per experimental design and the free ATRA and liposome encapsulated ATRA were given for 21 days at a dose of 0.60 mg/kg body weight/day after cell line implantation. After 21 days, mice were sacrificed at different time interval for ATRA level analysis in serum and lung tissue by HPLC method and the remaining mice were kept for anticancer study. The ATRA level increased significantly in serum and lung tissue in liposome encapsulated ATRA treated mice. In cancer bearing mice, tumor nodule formation decreased and life span increased after receiving liposome encapsulated ATRA treatment than free ATRA treated mice. This result implies that the liposome encapsulated ATRA has maintained more ATRA concentration in lung tissue and showed more inhibition on the lung tumor nodule formation. The results indicate a possible use of liposome encapsulated ATRA in prevention of lung metastasis.

Breast cancer metastasis suppressor 1 regulates hepatocellular carcinoma cell apoptosis via suppressing osteopontin expression

Breast cancer metastasis suppressor 1 (BRMS1) was originally identified as an active metastasis suppressor in human breast cancer. Loss of BRMS1 expression correlates with tumor progression, and BRMS1 suppresses several steps required for tumor metastasis. However, the role of BRMS1 in hepatocellular carcinoma (HCC) remains elusive. In this study, we found that the expression level of BRMS1 was significantly down-regulated in HCC tissues. Expression of BRMS1 in SK-Hep1 cells did not affect cell growth under normal culture conditions, but sensitized cells to apoptosis induced by serum deprivation or anoikis. Consistently, knockdown of endogenous BRMS1 expression in Hep3B cells suppressed cell apoptosis. We identified that BRMS1 suppresses osteopontin (OPN) expression in HCC cells and that there is a negative correlation between BRMS1 and OPN mRNA expression in HCC tissues. Moreover, knockdown of endogenous OPN expression reversed the anti-apoptosis effect achieved by knockdown of BRMS1. Taken together, our results show that BRMS1 sensitizes HCC cells to apoptosis through suppressing OPN expression, suggesting a potential role of BRMS1 in regulating HCC apoptosis and metastasis.

Effect of inhibition of the lysophosphatidic acid receptor 1 on metastasis and metastatic dormancy in breast cancer

BACKGROUND

Previous studies identified the human nonmetastatic gene 23 (NME1, hereafter Nm23-H1) as the first metastasis suppressor gene. An inverse relationship between Nm23-H1 and expression of lysophosphatidic acid receptor 1 gene (LPAR1, also known as EDG2 or hereafter LPA1) has also been reported. However, the effects of LPA1 inhibition on primary tumor size, metastasis, and metastatic dormancy have not been investigated.

METHODS

The LPA1 inhibitor Debio-0719 or LPA1 short hairpinned RNA (shRNA) was used. Primary tumor size and metastasis were investigated using the 4T1 spontaneous metastasis mouse model and the MDA-MB-231T experimental metastasis mouse model (n = 13 mice per group). Proliferation and p38 intracellular signaling in tumors and cell lines were determined by immunohistochemistry and western blot to investigate the effects of LPA1 inhibition on metastatic dormancy. An analysis of variance-based two-tailed t test was used to determine a statistically significant difference between treatment groups.

RESULTS

In the 4T1 spontaneous metastasis mouse model, Debio-0719 inhibited the metastasis of 4T1 cells to the liver (mean = 25.2 liver metastases per histologic section for vehicle-treated mice vs 6.8 for Debio-0719-treated mice, 73.0% reduction, P < .001) and lungs (mean = 6.37 lesions per histologic section for vehicle-treated mice vs 0.73 for Debio-0719-treated mice, 88.5% reduction, P < .001), with no effect on primary tumor size. Similar results were observed using the MDA-MB-231T experimental pulmonary metastasis mouse model. LPA1 shRNA also inhibited metastasis but did not affect primary tumor size. In 4T1 metastases, but not primary tumors, expression of the proliferative markers Ki67 and pErk was reduced by Debio-0719, and phosphorylation of the p38 stress kinase was increased, indicative of metastatic dormancy.

CONCLUSION

The data identify Debio-0719 as a drug candidate with metastasis suppressor activity, inducing dormancy at secondary tumor sites.

The metastasis suppressor KISS1 lacks antimetastatic activity in the C8161.9 xenograft model of melanoma

The objective of this study was to use the established xenograft model of human melanoma (C8161.9) to test a pharmacological approach to the effect of the metastasis suppressor KISS1. A KISS1 analog was used to inhibit the metastatic development of C8161.9 cells in nude mice. Further experiments were performed to test the validity of the C8161.9 model and test the connection between KISS1 expression and loss of metastatic potential. New clones of C8161.9 cells were obtained, with or without KISS1 expression, and were tested for metastasis formation. The absence of benefit in survival with the KISS1 analog compared with PBS prompted us to revisit the C8161.9 model. We found that the cells expressing KISS1, used in the previous study and obtained by transfection and single-cell cloning, were defective for both formation of orthotopic tumors and metastases. In mixing experiments, these cells could not suppress orthotopic tumor growth of KISS1-negative C8161.9 cells, suggesting that the suppression of metastasis by C8161.9-KISS1 cells may be intrinsic to the selected clone rather than related to KISS1 expression. Isolation of clones from parental C8161.9 cells in soft agar yielded cell populations that phenotypically and genotypically mimicked the KISS1-positive clone. In addition, new clones expressing KISS1 did not show any decrease in metastatic growth. These data demonstrate the heterogeneity of cell types in the C8161.9 cell line and the high risk of artifact linked to single-cell selection. A different xenograft model will be necessary to evaluate the use of KISS1 analogs as antimetastatic therapy.

Voltage-gated sodium channel activity promotes prostate cancer metastasis in vivo

Epigenetic upregulation of voltage-gated sodium channels (VGSCs) has been reported in a number of carcinoma cell lines and tissues. Furthermore, a large body of experimental evidence suggested that functional VGSC expression enhances various in vitro cell behaviours, such as directional motility, that would be involved in the metastatic cascade. However, it is not known if VGSC activity promotes metastasis in vivo. Here, using the Copenhagen rat model of prostate cancer and blocking VGSC activity in primary tumours with tetrodotoxin, we show (1) that the number of lung metastasis is reduced by >40% and (2) that lifespan is significantly improved.

The molecular biology of brain metastasis

Metastasis to the central nervous system (CNS) remains a major cause of morbidity and mortality in patients with systemic cancers. Various crucial interactions between the brain environment and tumor cells take place during the development of the cancer at its new location. The rapid expansion in molecular biology and genetics has advanced our knowledge of the underlying mechanisms involved, from invasion to final colonization of new organ tissues. Understanding the various events occurring at each stage should enable targeted drug delivery and individualized treatments for patients, with better outcomes and fewer side effects. This paper summarizes the principal molecular and genetic mechanisms that underlie the development of brain metastasis (BrM).

Comparison of protein expression profiles of different stages of lymph nodes metastasis in breast cancer

Breast cancer is the most common cancer among women worldwide. Breast cancer metastasis primarily happens through lymphatic system, where the extent of lymph node metastasis is the major factor influencing staging, prognosis and therapeutic decision of the disease. We aimed to study the protein expression changes in different N (regional lymph nodes) stages of breast cancer. Protein expression profiles of breast cancerous and adjacent normal tissues were mapped by proteomics approach that comprises of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and tandem mass spectrometry (LC-MS/MS) analysis. Calreticulin and tropomyosin alpha 3 chains were the common up-regulated proteins in N0, N1 and N2 stages of breast cancer. Potential biomarker for each N stage was HSP 70 for N0, 80 k protein H precursor and PDI for N1 stage while 78 kDa glucose-regulated protein was found useful for N2 stage. In addition, significant up-regulation of PDI A3 was detected only in the metastasized breast cancer. The up-regulation expression of these proteins in cancerous tissues can potentially use as indicators for diagnosis, treatment and prognosis of different N stages of breast cancer.

RKIP Suppresses Breast Cancer Metastasis to the Bone by Regulating Stroma-Associated Genes

In the past decade cancer research has recognized the importance of tumorstroma interactions for the progression of primary tumors to an aggressive and invasive phenotype and for colonization of new organs in the context of metastasis. The dialogue between tumor cells and the surrounding stroma is a complex and dynamic phenomenon, as many cell types and soluble factors are involved. While the function of many of the players involved in this cross talk have been studied, the regulatory mechanisms and signaling pathways that control their expression haven't been investigated in depth. By using a novel, interdisciplinary approach applied to the mechanism of action of the metastasis suppressor, Raf kinase inhibitory protein (RKIP), we identified a signaling pathway that suppresses invasion and metastasis through regulation of stroma-associated genes. Conceptually, the approach we developed uses a master regulator and expression arrays from breast cancer patients to formulate hypotheses based on clinical data. Experimental validation is followed by further bioinformatic analysis to establish the clinical significance of discoveries. Using RKIP as an example we show here that this multi-step approach can be used to identify gene regulatory mechanisms that affect tumor-stroma interactions that in turn influence metastasis to the bone or other organs.

Clinical and biological significance of KISS1 expression in prostate cancer

For men in the United States, prostate cancer (PCa) is the most frequent malignancy and the second leading cause of cancer mortality. The metastatic spread of PCa is responsible for most deaths related to PCa. Although KISS1 functions as a metastasis suppressor in various cancers, its expression levels and functions in PCa development and progression remain undetermined. The goals of this study were to correlate the expression levels of KISS1 in PCas with clinicopathologic characteristics and to assess the biological relevance of KISS1 to the viability and motility of PCa cells. Strong KISS1 staining was detected in benign prostate tissues, but the staining was weaker in primary and metastatic PCas (both P < 0.001, t-test). Furthermore, the low expression levels of KISS1 in PCas correlated with clinical stage (P < 0.01) and with KISS1R expression (P < 0.001). Overexpression of full-length KISS1 in low KISS1-expressing PC-3M cells, but not KFMΔSS, which lacks the secretion signal sequence, induced re-sensitization of cells to anoikis, although it had no effect on either cell proliferation or apoptosis. Overexpression of KISS1 also suppressed steps in the metastatic cascade, including motility and invasiveness. Moreover, cells overexpressing KISS1 were found to enhance chemosensitivity to paclitaxel. Collectively, our data suggest that KISS1 functions as a metastasis suppressor in PCas and may serve as a useful biomarker as well as a therapeutic target for aggressive PCas.

Breast cancer metastasis suppressor 1 (BRMS1) is destabilized by the Cul3-SPOP E3 ubiquitin ligase complex

Breast cancer metastasis suppressor 1 (BRMS1) suppresses metastasis without affecting primary tumorigenesis. The regulatory mechanism of BRMS1 at the protein level has not been revealed until recently. Here, we found that cullin 3 (Cul3), a component of E3 ubiquitin ligase, is a new binding partner of BRMS1 and the interaction between BRMS1 and Cul3 is mediated by the SPOP adaptor protein. Intriguingly, BRMS1 turns out to be a potent substrate that is ubiquitinated by the Cul3-SPOP complex. Knockdown of SPOP increases the level of BRMS1 protein and represses the expression of BRMS1 repressive target genes such as OPN and uPA in breast cancer cells. These results suggest that the novel regulatory mechanism of BRMS1 by Cul3-SPOP complex is important for breast cancer progression.

Recent advances in breast cancer metastasis suppressor 1

Metastasis is a complex process divided into a number of steps including detachment of tumor cells from the primary tumor, invasion, migration, intravasation, survival in the vasculature, extravasation, and colonization of the secondary site. Proteins that block metastasis without inhibiting primary tumor formation are known as metastasis suppressors; examples are NM23, Maspin, KAI1, KISS1, and MKK4. Breast cancer metastasis suppressor 1 (BRMS1) was identified as a suppressor of breast cancer metastasis in the late 1990s. In vitro and in vivo studies have confirmed that BRMS1 is a potent metastasis suppressor not limited to breast cancer. However, conflicting clinical observations regarding its role as a metastasis suppressor and its validity as a diagnostic biomarker warrant more in-depth clinical study. In this review, the authors provide an overview of its biology, function, action mechanism and pathological significance.

Adipocytes Promote B16BL6 Melanoma Cell Invasion and the Epithelial-to-Mesenchymal Transition

Metastatic melanoma is one of the most deadly and evasive types of cancer. On average, cancer patients with metastatic melanoma survive only 6-9 months after diagnosis. Epidemiological and animal studies suggest that obesity increases the metastatic ability of malignant melanoma, though the mechanism is not known. In the present studies, we assessed the ability of 3T3L1 adipocytes to modulate B16BL6 melanoma cell invasion and the Epithelial-to-Mesenchymal Transition (EMT). For this purpose, we induced the differentiation of 3T3L1 fibroblasts to adipocytes. Then, we collected the cell culture media from both fibroblasts and adipocytes and determined their effect on the invasive ability and EMT gene expression of B16BL6 melanoma cells. Results show that adipocyte media increased that ability of B16BL6 cells to invade. The higher invasive ability of B16BL6 melanoma cells was associated with increased expression of EMT genes such as Snai1, MMP9, Twist, and Vimentin. Additionally, the expression of the cell-to-cell adhesion protein E-cadherin and the metastasis suppressor gene Kiss1 were down-regulated in these B16BL6 cells. Also, adipocytes had high levels of the pro-inflammatory cytokine Interleukin 6 (IL-6). Treatment of B16BL6 cells with IL-6 elicited similar effects as the adipocyte media; IL-6 promoted the invasive ability of B16BL6 melanoma cells, increased the expression of Snai1, and decreased Kiss1 expression. IL-6 neutralization, however, did not have a visible effect on adipocyte media-induced invasion and snai1 staining. In summary, adipocytes may increase the invasive ability of B16BL6 melanoma cells by promoting EMT and decreasing the expression of genes such as E-cadherin and Kiss1.

Ob/ob serum promotes a mesenchymal cell phenotype in B16BL6 melanoma cells

In 2009, malignant melanoma was responsible for approximately 9,000 deaths in the US. These deaths are often associated with aggressive metastasis to secondary sites such as the lungs. Epidemiological and animal studies suggest that obesity is a risk factor for melanoma. Others have shown that B16BL6 melanoma cells metastasize more aggressively in obese ob/ob than in lean mice. However, the mechanism by which obesity promotes B16BL6 melanoma metastasis in ob/ob mice has not been identified. In the present study, we used serum obtained from control and ob/ob leptin-deficient obese mice to determine if obese serum increases the aggressive phenotype of melanoma cells. Results showed that ob/ob serum has higher levels of resistin, insulin, tPAI1, IL-6, TNF-α, and MCP-1 compared to control serum. We showed that ob/ob serum increases the invasive ability of B16BL6 melanomas. To further determine the mechanism by which ob/ob serum increases the invasive ability of melanomas, we determined the effect of ob/ob and control serum on genes associated with the epithelial-to-mesenchymal transition (EMT). Cancer cells with a mesenchymal phenotype have a higher metastatic ability. Snai1 and Twist are genes that are strongly associated with EMT and metastasis of melanomas. Our results showed that ob/ob serum increases the expression of Snai1 and Twist. Moreover, ob/ob serum increased matrix metalloproteast 9 (MMP9) activity and decreased the expression of E-cadherin and the metastasis suppressor gene Kiss1. In summary, results suggest that obesity may increase the metastatic ability of melanoma by promoting a mesenchymal cell phenotype.

Withaferin A inhibits breast cancer invasion and metastasis at sub-cytotoxic doses by inducing vimentin disassembly and serine 56 phosphorylation

Withaferin A (WFA) is purified from the plant Withania somnifera and inhibits the vimentin cytoskeleton. Vimentin overexpression in cancer correlates with metastatic disease, induction of epithelial to mesenchymal transition and reduced patient survival. As vimentin functions in cell motility, we wanted to test the hypothesis that WFA inhibits cancer metastasis by disrupting vimentin function. These data showed that WFA had weak cytotoxic and apoptotic activity at concentrations less than or equal to 500 nM, but retained potent anti-invasive activity at these low doses. Imaging of breast cancer cell lines revealed that WFA induces perinuclear vimentin accumulation followed by rapid vimentin depolymerization. A concomitant induction of vimentin ser56 phosphorylation was observed, which is consistent with vimentin disassembly. Structure activity relationships were established using a set of chemically modified WFA analogs and showed that the predicted vimentin-binding region of WFA is necessary to induce vimentin ser56 phosphorylation and for its anti-invasive activity. Pharmacokinetic studies in mice revealed that WFA reaches peak concentrations up to 2 μM in plasma with a half-life of 1.36 hr following a single 4 mg/kg dose. In a breast cancer metastasis mouse model, WFA showed dose-dependent inhibition of metastatic lung nodules and induced vimentin ser56 phosphorylation, with minimal toxicity to lung tissue. Based upon these studies, we conclude that WFA is a potent breast cancer anti-metastatic agent and the anti-metastatic activity of WFA is, at least in part, mediated through its effects on vimentin and vimentin ser56 phosphorylation.

Sorting nexin 6 interacts with breast cancer metastasis suppressor-1 and promotes transcriptional repression

Sorting nexin 6 (SNX6), a predominantly cytoplasmic protein involved in intracellular trafficking of membrane receptors, was identified as a TGF-β family interactor. However, apart from being a component of the Retromer, little is known about SNX6 cellular functions. Pim-1-dependent SNX6 nuclear translocation has been reported suggesting a putative nuclear role for SNX6. Here, we describe a previously non-reported association of SNX6 with breast cancer metastasis suppressor 1 (BRMS1) protein detected by a yeast two-hybrid screening. The interaction can be reconstituted in vitro and further FRET analysis confirmed the novel interaction. Additionally, we identified their coiled-coil domains as the minimal binding motives required for interaction. Since BRMS1 has been shown to repress transcription, we sought the ability of SNX6 to interfere with this nuclear activity. Using a standard gene reporter assay, we observed that SNX6 increases BRMS1-dependent transcriptional repression. Moreover, over-expression of SNX6 was capable of diminishing trans-activation in a dose-dependent manner.

Metastasis suppressors in human benign prostate, intraepithelial neoplasia, and invasive cancer: their prospects as therapeutic agents

Despite advances in diagnosis and treatment of prostate cancer, development of metastases remains a major clinical challenge. Research efforts are dedicated to overcome this problem by understanding the molecular basis of the transition from benign cells to prostatic intraepithelial neoplasia (PIN), localized carcinoma, and metastatic cancer. Identification of proteins that inhibit dissemination of cancer cells will provide new perspectives to define novel therapeutics. Development of antimetastatic drugs that trigger or mimic the effect of metastasis suppressors represents new therapeutic approaches to improve patient survival. This review focuses on different biochemical and cellular functions of metastasis suppressors known to play a role in prostate carcinogenesis and progression. Ten putative metastasis suppressors implicated in prostate cancer are discussed. CD44s is decreased in both PIN and cancer; Drg-1, E-cadherin, KAI-1, RKIP, and SSeCKS show similar expression between benign epithelia and PIN, but are downregulated in invasive cancer; whereas, maspin, MKK4, Nm23 and PTEN are upregulated in PIN and downregulated in cancer. Moreover, the potential role of microRNA in prostate cancer progression, the understanding of the cellular distribution and localization of metastasis suppressors, their mechanism of action, their effect on prostate invasion and metastasis, and their potential use as therapeutics are addressed.

Overexpression of KAI1 induces autophagy and increases MiaPaCa-2 cell survival through the phosphorylation of extracellular signal-regulated kinases

KAI1, a metastasis-suppressor gene belonging to the tetraspanin family, is known to inhibit cancer metastasis without affecting the primary tumorigenicity by inhibiting the epidermal growth factor (EGF) signaling pathway. Recent studies have shown that hypoxic conditions of solid tumors induce high-level autophagy and KAI1 expression. However, the relationship between autophagy and KAI1 remains unclear. By using transmission electron microscopy, confocal microscopy, and Western blotting, we found that KAI1 can induce autophagy in a dose- and time-dependent manner in the human pancreatic cell line MiaPaCa-2. KAI1-induced autophagy was confirmed by the expression of autophagy-related proteins LC3 and Beclin 1. KAI1 induces autophagy through phosphorylation of extracellular signal-related kinases rather than that of AKT. KAI1-induced autophagy protects MiaPaCa-2 cells from apoptosis and proliferation inhibition partially through the downregulation of poly [adenosine diphosphate (ADP)-ribose] polymerase (PARP) cleavage and caspase-3 activation.

Metastasis tumour suppressor-1 and the aggressiveness of prostate cancer cells

Previous studies have suggested that metastasis tumour suppressor-1 (MTSS1) plays a key role in cancer metastasis. Firstly, in this study we assessed MTSS1 expression levels in prostate cancer cell lines to reveal any changes in cell properties. Secondly, we aimed to clarify the cellular function of MTSS1 in prostate cancer cells. MTSS1 expression levels were assessed in different types of cancer cell lines through the RT-PCR analysis technique. The influence of MTSS1 was further examined via biological overexpression and knockdown in the prostate cancer cell lines. Two prostate cell lines were chosen for either knockdown or overexpression of the MTSS1 gene. The overexpression of MTSS1 in PC-3 human prostate cancer cells significantly suppressed the migratory, growth and adherence properties of the cells (p<0.01). By contrast, the knockdown of MTSS1 in DU-145 human prostate cancer cells dramatically enhanced these properties (p<0.001). We concluded that MTSS1 demonstrates the ability to play a role in controlling the metastatic nature of prostate cancer cells.

Vernonia cinerea Less. Inhibits Tumor Cell Invasion and Pulmonary Metastasis in C57BL/6 Mice

The effect of Vernonia cinerea Less. extract on the inhibition of lung metastasis induced by B16F-10 melanoma cells was studied in C57BL/6 mice. V cinerea extract significantly ( P < .001) inhibited lung tumor formation (78.8%) and significantly increased the life span (72.5%). Moreover, lung collagen hydroxyproline, uronic acid, and hexosamine and also serum sialic acid, γ-glutamyltransferase (GGT), and vascular endothelial growth factor (VEGF) levels were found to be significantly ( P < .001) lower in treated animals compared with untreated controls. Histopathological analysis of the lung tissues also correlated with these findings. V cinerea treatment significantly inhibited the invasion of B16F-10 melanoma cells across the collagen matrix of the Boyden chamber. V cinerea also inhibited the migration of B16F-10 melanoma cells across a polycarbonate filter in vitro. It downregulated the production and expression of proinflammatory cytokines such as TNF (tumor necrosis factor)-α, IL (interleukin)-1β, IL-6, and GM-CSF (granulocyte monocyte colony-stimulating factor). V cinerea extract administration could suppress or downregulate the expression of matrix metalloproteinase (MMP)-2, MMP-9, lysyl oxidase, prolyl hydroxylase, K-ras, extracellular signal-regulated kinase (ERK)-1, ERK-2, and VEGF and also upregulate the expression of nm-23, tissue inhibitor of metalloproteinase (TIMP-1), and TIMP-2 in the lung tissue of metastasis-induced animals. It also inhibited the protein expression of MMP-2 and MMP-9 in gelatin zymographic analysis of B16F-10 cells. These results indicate that V cinerea could inhibit the metastatic progression of B16F-10 melanoma cells in C57BL/6 mice by regulating MMPs, VEGF, prolyl hydroxylase, lysyl oxidase, ERK-1, ERK-2, TIMPs, nm23, and proinflammatory cytokine gene expression in metastatic lung tissue.

SERPINB5 and AKAP12 - expression and promoter methylation of metastasis suppressor genes in pancreatic ductal adenocarcinoma

BACKGROUND

Early metastasis and infiltration are survival limiting characteristics of pancreatic ductal adenocarcinoma (PDAC). Thus, PDAC is likely to harbor alterations in metastasis suppressor genes that may provide novel diagnostic and therapeutic opportunities. This study investigates a panel of metastasis suppressor genes in correlation to PDAC phenotype and examines promoter methylation for regulatory influence on metastasis suppressor gene expression and for its potential as a diagnostic tool.

METHODS

Metastatic and invasive potential of 16 PDAC cell lines were quantified in an orthotopic mouse model and mRNA expression of 11 metastasis suppressor genes determined by quantitative RT-PCR. Analysis for promoter methylation was performed using methylation specific PCR and bisulfite sequencing PCR. Protein expression was determined by Western blot.

RESULTS

In general, higher metastasis suppressor gene mRNA expression was not consistent with less aggressive phenotypes of PDAC. Instead, mRNA overexpression of several metastasis suppressor genes was found in PDAC cell lines vs. normal pancreatic RNA. Of the investigated metastasis suppressor genes, only higher AKAP12 mRNA expression was correlated with decreased metastasis (P < 0.05) and invasion scores (P < 0.01) while higher SERPINB5 mRNA expression was correlated with increased metastasis scores (P < 0.05). Both genes' promoters showed methylation, but only increased SERPINB5 methylation was associated with loss of mRNA and protein expression (P < 0.05). SERPINB5 methylation was also directly correlated to decreased metastasis scores (P < 0.05).

CONCLUSIONS

AKAP12 mRNA expression was correlated to attenuated invasive and metastatic potential and may be associated with less aggressive phenotypes of PDAC while no such evidence was obtained for the remaining metastasis suppressor genes. Increased SERPINB5 mRNA expression was correlated to increased metastasis and mRNA expression was regulated by methylation. Thus, SERPINB5 methylation was directly correlated to metastasis scores and may provide a diagnostic tool for PDAC.

KISS1 over-expression suppresses metastasis of pancreatic adenocarcinoma in a xenograft mouse model

Identifying molecular targets for treatment of pancreatic cancer metastasis is critical due to the high frequency of dissemination prior to diagnosis of this lethal disease. Because the KISS1 metastasis suppressor is expressed at reduced levels in advanced pancreatic cancer, we hypothesized that re-expression of KISS1 would reduce metastases. Highly metastatic S2VP10 cells expressing luciferase (S2VP10L) were transfected with a FLAG-tagged version of KISS1 (KFM), KFMΔSS (with deleted secretion signal sequence), or pcDNA3 control plasmid (CP) and expression was confirmed by RTQ-PCR. SCID mice were implanted orthotopically with S2VP10L cells or transfectants and tumor growth and metastases were monitored using bioluminescence imaging. Mice with S2VP10L-KISS1 tumors developed fewer liver (98%) and lung (99%) metastases than S2VP10L. Unexpectedly, mice with S2VP10L-KFMΔSS tumors also had reduced liver and lung metastases, but had more metastases than mice with S2VP10L-KISS. KISS1 protein was found in the cytoplasm of both KFMΔSS and KISS1-expressing orthotopic tumors by immunohistochemistry. Metastases were not found in lungs of mice with S2VP10L-KISS1 tumors; whereas, KFMΔSS lung sections had regions of concentrated KISS1 staining, suggesting that secretion of KISS1 is needed to reduce metastasis significantly. These data suggest induction of KISS1 expression has potential as an adjuvant treatment for pancreatic cancer.

Validated prediction of clinical outcome in sarcomas and multiple types of cancer on the basis of a gene expression signature related to genome complexity

Sarcomas are heterogeneous and aggressive mesenchymal tumors. Histological grading has so far been the best predictor for metastasis-free survival, but it has several limitations, such as moderate reproducibility and poor prognostic value for some histological types. To improve patient grading, we performed genomic and expression profiling in a training set of 183 sarcomas and established a prognostic gene expression signature, complexity index in sarcomas (CINSARC), composed of 67 genes related to mitosis and chromosome management. In a multivariate analysis, CINSARC predicts metastasis outcome in the training set and in an independent 127 sarcomas validation set. It is superior to the Fédération Francaise des Centres de Lutte Contre le Cancer grading system in determining metastatic outcome for sarcoma patients. Furthermore, it also predicts outcome for gastrointestinal stromal tumors (GISTs), breast carcinomas and lymphomas. Application of the signature will permit more selective use of adjuvant therapies for people with sarcomas, leading to decreased iatrogenic morbidity and improved outcomes for such individuals.

BRMS1 expression alters the ultrastructural, biomechanical and biochemical properties of MDA-MB-435 human breast carcinoma cells: an AFM and Raman microspectroscopy study

Restoring BReast cancer Metastasis Suppressor 1 (BRMS1) expression suppresses metastasis in MDA-MB-435 human breast carcinoma cells at ectopic sites without affecting tumor formation at orthotopic site in the body. BRMS1 expression induces many phenotypic alterations in 435 cells such as cell adhesion, cytoskeleton rearrangement, and the down regulation of epidermal growth factor receptor (EGFR) expression. In order to better understand the role of cellular biomechanics in breast cancer metastasis, the qualitative and quantitative detection of cellular biomechanics and biochemical composition is urgently needed. In the present work, using atomic force microscopy (AFM) and fluorescent microscopy we revealed that BRMS1 expression in 435 cells induced reorganization of F-actin and caused alteration in cytoarchitectures (cell topography and ultrastructure). Results from AFM observed increase in biomechanical properties which include cell adhesion, cellular spring constant, and Young's modulus in 435/BRMS1 cells. Raman microspectroscopy showed weaker vibrational spectroscopic bands in 435/BRMS1 cells, implying decrease in concentration of cellular biochemical components in these cells. This was despite the similar spectral patterns observed between 435 and 435/BRMS1 cells. This work demonstrated the feasibility of applying AFM and Raman techniques for in situ measurements of the cellular biomechanics and biochemical components of breast carcinoma cells. It provides vital clues in understanding of the role of cellular biomechanics in cancer metastasis, and further the development of new techniques for early diagnosis of breast cancer.

Development and progression of colorectal neoplasia

A variety of genetic and molecular alterations underlie the development and progression of colorectal neoplasia (CRN). Most of these cancers arise sporadically due to multiple somatic mutations and genetic instability. Genetic instability includes chromosomal instability (CIN) and microsatellite instability (MSI), which is observed in most hereditary non-polyposis colon cancers (HNPCCs) and accounts for a small proportion of sporadic CRN. Although many biomarkers have been used in the diagnosis and prediction of the clinical outcomes of CRNs, no single marker has established value. New markers and genes associated with the development and progression of CRNs are being discovered at an accelerated rate. CRN is a heterogeneous disease, especially with respect to the anatomic location of the tumor, race/ethnicity differences, and genetic and dietary interactions that influence its development and progression and act as confounders. Hence, efforts related to biomarker discovery should focus on identification of individual differences based on tumor stage, tumor anatomic location, and race/ethnicity; on the discovery of molecules (genes, mRNA transcripts, and proteins) relevant to these differences; and on development of therapeutic approaches to target these molecules in developing personalized medicine. Such strategies have the potential of reducing the personal and socio-economic burden of CRNs. Here, we systematically review molecular and other pathologic features as they relate to the development, early detection, diagnosis, prognosis, progression, and prevention of CRNs, especially colorectal cancers (CRCs).

KLF17 is a negative regulator of epithelial-mesenchymal transition and metastasis in breast cancer

Metastasis is a complex multistep process, which requires the concerted action of many genes and is the primary cause of cancer death. Both pathways that regulate metastasis enhancement and those that regulate its suppression contribute to the tumour dissemination process. To identify new metastasis suppressors, we set up a forward genetic screen in a mouse model. We transduced a genome-wide RNA interference (RNAi) library into the non-metastatic 168FARN breast cancer cell line and orthotopically transplanted the cells into mouse mammary fat pads. We then selected cells that could metastasize to the lung and identified an RNAi for the KLF17 gene. Conversely, we demonstrate that ectopic expression of KLF17 in a highly metastatic 4T1 breast cancer cell line inhibits the ability of cells to metastasize from the mammary fat pad to the lung. We also show that suppression of KLF17 expression promotes breast cancer cell invasion and epithelial-mesenchymal transition (EMT), and that KLF17 protein functions by directly binding to the promoter region of Id1 (which encodes a key metastasis regulator in breast cancer) to inhibit its transcription. Finally, we demonstrate that KLF17 expression is significantly downregulated in primary human breast cancer samples and that the combined expression pattern of KLF17 and Id1 can serve as a potential biomarker for lymph node metastasis in breast cancer.

Breast cancer metastasis suppressor 1 coordinately regulates metastasis-associated microRNA expression

Breast cancer metastasis suppressor 1 (BRMS1) suppresses metastasis of multiple tumor types without blocking tumorigenesis. BRMS1 forms complexes with SIN3, histone deacetylases and selected transcription factors that modify metastasis-associated gene expression (e.g., EGFR, OPN, PI4P5K1A, PLAU). microRNA (miRNA) are a recently discovered class of regulatory, noncoding RNA, some of which are involved in neoplastic progression. Based on these data, we hypothesized that BRMS1 may also exert some of its antimetastatic effects by regulating miRNA expression. MicroRNA arrays were done comparing small RNAs that were purified from metastatic MDA-MB-231 and MDA-MB-435 and their nonmetastatic BRMS1-transfected counterparts. miRNA expression changed by BRMS1 were validated using SYBR Green RT-PCR. BRMS1 decreased metastasis-promoting (miR-10b, -373 and -520c) miRNA, with corresponding reduction of their downstream targets (e.g., RhoC which is downstream of miR-10b). Concurrently, BRMS1 increased expression of metastasis suppressing miRNA (miR-146a, -146b and -335). Collectively, these data show that BRMS1 coordinately regulates expression of multiple metastasis-associated miRNA and suggests that recruitment of BRMS1-containing SIN3:HDAC complexes to, as yet undefined, miRNA promoters might be involved in the regulation of cancer metastasis.

Linking metastasis suppression with metastamiR regulation

Cancer metastasis requires the coordinate expression of multiple genes during every step of the metastatic cascade. Molecules that regulate these genetic programs have the potential to impact metastasis at multiple levels. Breast cancer metastasis suppressor 1 (BRMS1) suppresses metastasis by inhibiting multiple steps in the cascade through regulation of many protein-encoding, metastasis-associated genes as well as metastasis-regulatory microRNA, termed metastamiR. In this Feature , we will highlight connections between BRMS1 biology and regulation of metastamiR.