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.     

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.     

Suppression of human melanoma metastasis by the metastasis suppressor gene, BRMS1

We recently identified a novel metastasis suppressor gene, BRMS1, in breast cancer. Since the BRMS1 gene maps to chromosome 11q13.1-q13.2 and since chromosome 11q defects have been described in various stages of human melanoma progression, we hypothesized that BRMS1 may function as a tumor or metastasis suppressor in melanomas as well. Quantitative real-time RT-PCR revealed that BRMS1 mRNA expression was high in melanocytes, considerably reduced in early melanoma-derived cell lines, and barely detectable in advanced/metastatic cell lines. Stable transfectants of BRMS1 in the human melanoma cell lines MelJuSo and C8161.9 did not alter the tumorigenicity of either cell line, but significantly suppressed metastasis compared to vector-only transfectants. Orthotopic tumors continued to express BRMS1, but expression was lost in lung metastases. In vitro morphology, growth rate, and histology of BRMS1 transfectants were similar to controls. BRMS1 transfectants were less invasive in a collagen sandwich assay and had restored homotypic gap junctional intercellular communication (GJIC). Thus, BRMS1 functions as a metastasis suppressor in more than one tumor type (i.e., breast carcinoma and cutaneous melanoma) by modifying several metastasis-associated phenotypes.     

肿瘤转移抑制基因BRMS1的表达分析及机制研究进展

乳腺癌转移抑制基因1(BRMS1)是一个有活性的肿瘤转移抑制基因,参与抑制乳腺癌、黑素瘤、鼻咽癌、非小细胞肺癌、卵巢癌等恶性肿瘤的转移。BRMS1编码蛋白主要通过转录调控转移相关靶基因,参与调节细胞凋亡、细胞通讯、肿瘤血管新生等多种细胞事件。从BRMS1基因的分子结构、表达调控、生物学功能以及转移抑制机理等方面对BRMS1的研究进展做简要回顾。     

Effect of Chronic Psychological Stress on Liver Metastasis of Colon Cancer in Mice

Metastasis to the liver is a main factor in colorectal cancer mortality. Previous studies suggest that chronic psychological stress is important in cancer progression, but its effect on liver metastasis has not been investigated. To address this, we established a liver metastasis model in BALB/c nude mice to investigate the role of chronic stress in liver metastasis. Our data suggest that chronic stress elevates catecholamine levels and promotes liver metastasis. Chronic stress was also associated with increased tumor associated macrophages infiltration into the primary tumor and increased the expression of metastatic genes. Interestingly, β-blocker treatment reversed the effects of chronic stress on liver metastasis. Our results suggest the β-adrenergic signaling pathway is involved in regulating colorectal cancer progression and liver metastasis. Additionally, we submit that adjunctive therapy with a β-blocker may complement existing colorectal cancer therapies.     

Down-regulation of tumor suppressor in lung cancer 1 (TSLC1) expression correlates with poor prognosis in patients with colon cancer

Tumor suppressor in lung cancer 1 (TSLC1), a novel tumor suppressor gene, has been reported to be frequently inactivated in a variety of human malignant tumors. The aim of this study was to detect TSLC1 expression in human colon cancer and to analyze its association with prognosis of patients with colon cancer. Using quantitative real-time PCR and Western blot analysis, we found significantly decreased expression of TSLC1 in primary colon tumor tissues (n?=?30) compared with adjacent normal tissues. Immunohistochemistry analysis also found decreased TSLC1 expression in 41.3?% (33/80) colon tumor tissues. In clinicopathological analysis, loss of TSLC1 expression significantly correlated with female gender and lymph node metastasis of colon cancer patients (P?<?0.05). In addition, decreased expression of TSLC1 in tumors was found to be closely associated with a poor prognosis (P?=?0.037, log-rank test), and multivariate analysis showed that lower TSLC1 protein expression was an independent prognostic factor for colon cancer patients. Our study suggests that down-regulated expression of TSLC1 may play an important role in the progression of colon cancer and TSLC1 expression may serve as a useful marker for the prognostic evaluation of patients with colon cancer.     

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.     

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.     

Allelic variation and differential expression of the mSIN3A histone deacetylase complex gene Arid4b promote mammary tumor growth and metastasis

Accumulating evidence suggests that breast cancer metastatic progression is modified by germline polymorphism, although specific modifier genes have remained largely undefined. In the current study, we employ the MMTV-PyMT transgenic mouse model and the AKXD panel of recombinant inbred mice to identify AT-rich interactive domain 4B (Arid4b; NM_194262) as a breast cancer progression modifier gene. Ectopic expression of Arid4b promoted primary tumor growth in vivo as well as increased migration and invasion in vitro, and the phenotype was associated with polymorphisms identified between the AKR/J and DBA/2J alleles as predicted by our genetic analyses. Stable shRNA-mediated knockdown of Arid4b caused a significant reduction in pulmonary metastases, validating a role for Arid4b as a metastasis modifier gene. ARID4B physically interacts with the breast cancer metastasis suppressor BRMS1, and we detected differential binding of the Arid4b alleles to histone deacetylase complex members mSIN3A and mSDS3, suggesting that the mechanism of Arid4b action likely involves interactions with chromatin modifying complexes. Downregulation of the conserved Tpx2 gene network, which is comprised of many factors regulating cell cycle and mitotic spindle biology, was observed concomitant with loss of metastatic efficiency in Arid4b knockdown cells. Consistent with our genetic analysis and in vivo experiments in our mouse model system, ARID4B expression was also an independent predictor of distant metastasis-free survival in breast cancer patients with ER+ tumors. These studies support a causative role of ARID4B in metastatic progression of breast cancer.     

Prognostic significance of Beclin 1 in intrahepatic cholangiocellular carcinoma

Autophagy enables cells to recycle long-lived proteins or damaged organelles. Beclin 1 plays important roles in autophagy, differentiation, apoptosis and the development and progression of cancer, but the expression of Beclin 1 and its possible role in primary intrahepatic cholangiocarcinoma (ICC) has not been reported yet. This study aimed to investigate Beclin 1 expression and its prognostic significance in ICC. First, we assessed the expression levels of Becn1 by real-time PCR in 50 ICC samples and found Becn1 mRNA expression was markedly increased in 78% (39 of 50) samples compared with normal bile duct epithelium. Beclin 1 protein expression in 108 tumor specimens from patients diagnosed with ICC was examined by immunohistochemistry and the correlation between Beclin 1 expression and clinicopathological factors were investigated. Immunopositivity for Beclin 1 was found in 72.2% (78 of 108) samples and low Beclin 1 expression was significantly associated with lymph node metastasis. The correlation between Beclin 1 expression and metastasis was validated in 46 ICC samples with lymph node metastasis. In survival analysis, low Beclin 1 expression was associated with worse overall survival (OS; p = 0.025) and disease-free survival (DFS; p = 0.027). In multivariate analysis, Beclin 1 expression, intrahepatic metastasis, lymph node metastasis and tumor size were found to be independent prognostic factors of OS. Thus, our results suggested the expression of Beclin 1 was correlated with progression and metastasis of ICC and it might serve as a novel prognostic marker for patients with ICC.     

Purification and characterisation of the breast cancer metastasis suppressor, BRMS1

The breast cancer metastasis suppressor 1 (BRMS1) is a member of a family of proteins that actively suppress tumour metastasis. Understanding BRMS1 mediated metastasis suppression is critical to the development of new therapies designed to prevent and treat patients with late stage breast cancer. To aid research into the functional aspects that underpin BRMS1 mediated metastasis suppression we have expressed and purified recombinant BRMS1 and produced BRMS1 polyclonal antibodies. Using these antibodies to immunoprecipitate endogenous BRMS1 containing complexes from MCF7 breast cancer cell lines we have identified, by mass spectrometry, the small heat shock protein Hsp27 in complex with BRMS1. We also show that the expression of both BRMS1 and Hsp27 are inversely correlated with metastatic potential.     

Prognostic significance of Beclin 1 in intrahepatic cholangiocellular carcinoma

Autophagy enables cells to recycle long-lived proteins or damaged organelles. Beclin 1 plays important roles in autophagy, differentiation, apoptosis and the development and progression of cancer, but the expression of Beclin 1 and its possible role in primary intrahepatic cholangiocarcinoma (ICC) has not been reported yet. This study aimed to investigate Beclin 1 expression and its prognostic significance in ICC. First, we assessed the expression levels of Becn1 by real-time PCR in 50 ICC samples and found Becn1 mRNA expression was markedly increased in 78% (39 of 50) samples compared with normal bile duct epithelium. Beclin 1 protein expression in 108 tumor specimens from patients diagnosed with ICC was examined by immunohistochemistry and the correlation between Beclin 1 expression and clinicopathological factors were investigated. Immunopositivity for Beclin 1 was found in 72.2% (78 of 108) samples and low Beclin 1 expression was significantly associated with lymph node metastasis. The correlation between Beclin 1 expression and metastasis was validated in 46 ICC samples with lymph node metastasis. In survival analysis, low Beclin 1 expression was associated with worse overall survival (OS; p = 0.025) and disease-free survival (DFS; p = 0.027). In multivariate analysis, Beclin 1 expression, intrahepatic metastasis, lymph node metastasis and tumor size were found to be independent prognostic factors of OS. Thus, our results suggested the expression of Beclin 1 was correlated with progression and metastasis of ICC and it might serve as a novel prognostic marker for patients with ICC.     

Proteomics-based strategy to delineate the molecular mechanisms of the metastasis suppressor gene BRMS1

The breast cancer metastasis suppressor 1 (BRMS1) gene has been shown to suppress metastasis without affecting the growth of the primary tumor in mouse models. It has also been shown to suppress the metastasis of tumors derived from breast, melanoma, and, more recently, ovarian carcinoma (see ref 1). However, how BRMS1 exerts its metastasis suppressor function remains unknown. To shed light into its metastatic mechanism of action, the sensitive 2D-DIGE analysis coupled with MS has been used to identify proteins differentially expressed by either overexpressing (Mel-BRMS1) or silencing BRMS1 (sh635) in a melanoma cell line. After comparison of the protein profiles from WT, Mel-BRMS1, and sh635 cells, 79 spots were found to be differentially expressed. Mass spectrometry analysis allowed the unambiguous identification of 55 polypeptides, corresponding to 43 different proteins. Interestingly, more than 75% of the identified proteins were down-regulated in Mel-BRMS1 cells compared to WT. In contrast, all the identified proteins in sh635 cells extracts were up-regulated compared to WT. Most of the deregulated proteins are involved in cell growth/maintenance and signal transduction among other cell processes. Six differentially expressed proteins (Hsp27, Alpha1 protease inhibitor, Cofilin1, Cathepsin D, Bone morphogenetic protein receptor2, and Annexin2) were confirmed by immunoblot and functional assays. Excellent correlation was found between DIGE analysis and immunoblot results, indicating the reliability of the analysis. Available evidence on the reported functions of the identified proteins supports the emerging role of BRMS1 as negative regulator of the metastasis development. This work opens an avenue for the molecular mechanisms' characterization of metastasis suppressor genes with the aim to understand their roles.