Is there a genetic signature for liver metastasis in colorectal cancer?

Exploring the metastasis-related biomarker and carcinogenic mechanism in liver cancer based on single cell technology

Background

Hepatocellular carcinoma (HCC) is a fatal primary malignancy characterized by high invasion and migration. We aimed to explore the underlying metastasis-related mechanism supporting the development of HCC.

Methods

The dataset of single cell RNA-seq (GSE149614) were collected for cell clustering by using the Seurat R package, the FindAllMarkers function was used to find the highly expression and defined the cell cluster. The WebGestaltR package was used for the GO and KEGG function analysis of shared genes, the Gene Set Enrichment Analysis (GSVA) was performed by clusterProfiler R package, the hTFtarget database was used to identify the crucial transcription factors (TFs), the Genomics of Drug Sensitivity in Cancer (GDSC) database was used for the drug sensitivity analysis. Finally, the overexpression and trans-well assay was used for gene function analysis.

Results

We obtained 9 cell clusters from the scRNA-seq data, including the nature killer (NK)/T cells, Myeloid cells, Hepatocytes, Epithelial cells, Endothelial cells, Plasma B cells, Smooth muscle cells, B cells, Liver bud hepatic cells. Further cell ecological analysis indicated that the Hepatocytes and Endothelial cell cluster were closely related to the cancer metastasis. Subsequently, the NDUFA4L2-Hepatocyte, GTSE1-Hepatocyte, ENTPD1-Endothelial and NDUFA4L2-Endothelial were defined as metastasis-supporting cell clusters, in which the NDUFA4L2-Hepatocyte cells was closely related to angiogenesis, while the NDUFA4L2-Endothelial was related with the inflammatory response and complement response. The overexpression and trans-well assay displayed that NDUFA4L2 exhibited clearly metastasis-promoting role in HCC progression.

Conclusion

We identified and defined 4 metastasis-supporting cell clusters by using the single cell technology, the specify shared gene was observed and played crucial role in promoting cancer progression, our findings were expected to provide new insight in control cancer metastasis.

Deconstructing Immune Cell Infiltration in Human Colorectal Cancer: A Systematic Spatiotemporal Evaluation

Cancer-related immunity has been identified as playing a key role in the outcome of colorectal cancer (CRC); however, the exact mechanisms are only partially understood. In this study, we evaluated a total of 242 surgical specimen of CRC patients using tissue microarrays and immunohistochemistry to evaluate tumor infiltrating immune cells (CD3, CD4, CD8, CD20, CD23, CD45 and CD56) and immune checkpoint markers (CTLA-4, PD-L1, PD-1) in systematically selected tumor regions and their corresponding lymph nodes, as well as in liver metastases. Additionally, an immune panel gene expression assay was performed on 12 primary tumors and 12 consecutive liver metastases. A higher number of natural killer cells and more mature B cells along with PD-1⁺ expressing cells were observed in the main tumor area as compared to metastases. A higher number of metastatic lymph nodes were associated with significantly lower B cell counts. With more advanced lymph node metastatic status, higher leukocyte—particularly T cell numbers—were observed. Eleven differentially expressed immune-related genes were found between primary tumors and liver metastases. Also, alterations of the innate immune response and the tumor necrosis factor superfamily pathways had been identified.

Distant metastasis identification based on optimized graph representation of gene interaction patterns

Metastasis is a major cause of cancer morbidity and mortality, and most cancer deaths are caused by cancer metastasis rather than by the primary tumor. The prediction of metastasis based on computational methods has not been explored much in the previous research. In this study, we proposed a graph convolutional network embedded with a graph learning (GL) module, named glmGCN, to predict the distant metastasis of cancer. Both the mRNA and lncRNA expressions were used to provide more genetic information than using the mRNA alone and we used them to construct gene interaction graph representation to consider the effect of genetic interaction. Then, the prediction of the cancer metastasis was performed under a GCN framework, which extracted informative and advanced features from the built non-regular graph structures. Particularly, a GL module was embedded in the proposed glmGCN to learn an optimal graph representation of the gene interaction. We firstly constructed the protein-protein interaction network to represent the initial gene(node) relationship graph. Then, through the GL module, a new graph representation was built which optimally learned the gene interaction strength. Finally, the GCN was adopted to identify the distant metastasis cases. It is worth mentioning that the proposed method pays more attentions on the gene-gene relation than the previous GCN-based method, so more accurate prediction performance can be obtained. The glmGCN was trained based on two types of cancer and was further validated using two other cancer types. A series of experiments have shown that the effectiveness of the proposed method. The implementation for the proposed method is available at https://github.com/RanSuLab/Metastasis-glmGCN.

Identification of Candidate Biomarkers and Prognostic Analysis in Colorectal Cancer Liver Metastases

Background

Colorectal cancer (CRC), one of the most common malignant tumors worldwide, has a high mortality rate, especially for patients with CRC liver metastasis (CLM). However, CLM pathogenesis remains unclear.

Methods

We integrated multiple cohort datasets and databases to clarify and verify potential key candidate biomarkers and signal transduction pathways in CLM. GEO2R, DAVID 6.8, ImageGP, STRING, UALCAN, ONCOMINE, THE HUMAN PROTEIN ATLAS, GEPIA 2.0, cBioPortal, TIMER 2.0, DRUGSURV, CRN, GSEA 4.0.3, FUNRICH 3.1.3 and R 4.0.3 were utilized in this study.

Results

Sixty-three pairs of matched colorectal primary cancer and liver metastatic gene expression profiles were screened from three gene expression profiles (GSE6988, GSE14297 and GSE81558). Thirty-one up-regulated genes and four down-regulated genes were identified from these three gene expression profiles and verified by another gene expression profiles (GSE 49355) and TCGA database. Two pathways (IGFBP-IGF signaling pathway and complement-coagulation cascade), eighteen key differentially expressed genes (DEGs), six hub genes (SPARCL1, CDH2, CP, HP, TF and SERPINA5) and two biomarkers (CDH2 and SPARCL1) with significantly prognostic values were screened by multi-omics data analysis and verified by Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) cohort.

Conclusions

In this study, we identified a robust set of potential candidate biomarkers in CLM, which would provide potential value for early diagnosis and prognosis, and would promote molecular targeting therapy for CRC and CLM.

The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management

Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.

The Neuropeptide System and Colorectal Cancer Liver Metastases: Mechanisms and Management

Colorectal cancer (CRC), classified as the third most prevalent cancer worldwide, remains to be a clinical and research challenge. It is estimated that ~50% of CRC patients die from distant metastases, with treatment of this complication still posing significant difficulties. While liver metastasis (LM) cascade is known in the literature, its mechanisms are still unclear and remain studied in different research models. A connection is suggested between nervous system dysfunctions and a range of Neurotransmitters (Nts) (including Neuropeptides, NPs), Neurotrophins (Ntt) and their receptors (Rs) in CRC liver metastasis development. Studies on the role of NP/NP-Rs in the progression and metastasis of CRC, show the complexity of brain–tumor interactions, caused by their different forms of release to the extracellular environment (endocrine, autocrine, paracrine and neurocrine). Many stages of LM are connected to the activity of pro-inflammatory, e.g., Corticotropin-releasing Hormone Receptor 1 (CRHR1), Neuropeptide Y (NPY) and Neurotensin (NT), anti-inflammatory, e.g., Calcitonin Gene-related Peptide (CGRP), CRHR2 and Vasoactive Intestinal Polypeptide (VIP) or dual role neuropeptides, e.g., Substance P (SP). The regulation of the local immunological profile (e.g., CRH/CRHRs), dysfunctions of enteroprotective role of NPs on epithelial cells (e.g., NT/NT-R), as well as structural-functional changes in enteric nervous system innervation of the tumor are also important. More research is needed to understand the exact mechanisms of communication between the neurons and tumor cells. The knowledge on the mechanisms regulating tumor growth and different stages of metastasis, as well as effects of the action of a numerous group of Nts/NPs/Ntt as growth factors, have implications for future therapeutic strategies. To obtain the best treatment outcomes, it is important to use signaling pathways common for many NPs, as well to develop a range of broad-spectrum antagonists. This review aims to summarize the current knowledge on the importance of neuroactive molecules in the promotion of the invasion-metastasis cascade in CRC, as well as the improvements of clinical management of CRC liver metastasis.

Molecular Mechanisms by Which S100A4 Regulates the Migration and Invasion of PGCCs With Their Daughter Cells in Human Colorectal Cancer

Recently, an increasing number of evidences have shown that polyploid giant cancer cells (PGCCs) could generate daughter cells with a strong migration and invasion ability, which have been implicated in cancer recurrence and metastasis. However, the underlying molecular mechanisms of PGCCs with their daughter cells remain largely unclear. In vitro and in vivo experiments combined with 222 cases of human colorectal cancer (CRC) samples were used to identify the molecular mechanisms of S100A4-related proteins regulating the invasion and metastasis of PGCCs with their daughter cells. PGCCs with their daughter cells had high migration, invasion, and proliferation abilities compared to control cells; these were significantly inhibited after S100A4 knockdown. The high expression of cathepsin B, cyclin B1, TRIM21, and Annexin A2 were significantly downregulated after S100A4 knockdown, while the overexpression of S100A4, cathepsin B, cyclin B1, and S100A10 were significantly downregulated after TRIM21 knockdown in PGCCs with their daughter cells. The tumorigenic and metastatic ability of PGCCs with their daughter cells in vivo was significantly stronger compared to the untreated cells, which was significantly decreased after S100A4 knockdown. Moreover, the expression of S100A4-related proteins was positively correlated with the malignancy degree of human CRC, and maintained a high level in lymph node metastasis. S100A4 and TRIM21 may regulate each other to affect the expression and subcellular localization of cyclin B1, and participate in regulating the structure and function of Annexin A2/S100A10 complex, affecting downstream cathepsin B, resulting in the invasion and metastasis of PGCCs with their daughter cells. Besides, 14-3-3 ζ/δ and Ezrin may be involved in the motility and invasion of PGCCs with their daughter cells via cytoskeletal constructions with S100A4.

Insulin-Like Growth Factor 2 (IGF2) Signaling in Colorectal Cancer-From Basic Research to Potential Clinical Applications

Colorectal cancer (CRC) is one of the most common cancers in men and women worldwide as well as is the leading cause of death in the western world. Almost a third of the patients has or will develop liver metastases. While genetic as well as epigenetic mechanisms are important in CRC pathogenesis, the basis of the most cases of cancer is unknown. High spatial and inter-patient variability of the molecular alterations qualifies this cancer in the group of highly heterogeneous tumors, which makes it harder to elucidate the mechanisms underlying CRC progression. Determination of highly sensitive and specific early diagnosis markers and understanding the cellular and molecular mechanism(s) of cancer progression are still a challenge of the current era in oncology of solid tumors. One of the accepted risk factors for CRC development is overexpression of insulin-like growth factor 2 (IGF2), a 7.5-kDa peptide produced by liver and many other tissues. IGF2 is the first gene discovered to be parentally imprinted. Loss of imprinting (LOI) or aberrant imprinting of IGF2 could lead to IGF2 overexpression, increased cell proliferation, and CRC development. IGF2 as a mitogen is associated with increased risk of developing colorectal neoplasia. Higher serum IGF2 concentration as well as its tissue overexpression in CRC compared to control are associated with metastasis. IGF2 protein was one of the three candidates for a selective marker of CRC progression and staging. Recent research indicates dysregulation of different micro- and long non-coding RNAs (miRNAs and lncRNAs, respectively) embedded within the IGF2 gene in CRC carcinogenesis, with some of them indicated as potential diagnostic and prognostic CRC biomarkers. This review systematises the knowledge on the role of genetic and epigenetic instabilities of IGF2 gene, free (active form of IGF2) and IGF-binding protein (IGFBP) bound (inactive form), paracrine/autocrine secretion of IGF2, as well as mechanisms of inducing dysplasia in vitro and tumorigenicity in vivo. We have tried to answer which molecular changes of the IGF2 gene and its regulatory mechanisms have the most significance in initiation, progression (including liver metastasis), prognosis, and potential anti-IGF2 therapy in CRC patients.

HCMDB: the human cancer metastasis database

Metastasis is the main event leading to death in cancer patients. Over the past decade, high-throughput technologies have provided genome-wide view of transcriptomic changes associated with cancer metastases. Many microarray and RNA sequencing studies have addressed metastases-related expression patterns in various types of cancer, and the number of relevant works continues to increase rapidly. These works have characterized genes that orchestrate the metastatic phenotype of cancer cells. However, these expression data have been deposited in various repositories, and efficiently analyzing these data is still difficult because of the lack of an integrated data mining platform. To facilitate the in-depth analyses of transcriptome data on metastasis, it is quite important to make a comprehensive integration of these metastases-related expression data. Here, we presented a database, HCMDB (the human cancer metastasis database, http://hcmdb.i-sanger.com/index), which is freely accessible to the research community query cross-platform transcriptome data on metastases. HCMDB is developed and maintained as a useful resource for building the systems-biology understanding of metastasis.

Expression and Localization of Cathepsins B, D and G in Cancer Stem Cells in Liver Metastasis From Colon Adenocarcinoma

Aim

We have previously identified and characterized cancer stem cell (CSC) subpopulations in liver metastasis from colon adenocarcinoma (LMCA). In this study we investigated the expression and localization of cathepsins B, D and G, in relation to these CSCs.

Methods

3,3-Diaminobenzidine (DAB) immunohistochemical (IHC) staining for cathepsins B, D and G was performed on 4μm-thick formalin-fixed paraffin-embedded LMCA sections from nine patients. Immunofluorescence (IF) IHC staining was performed on three representative samples of LMCA from the original cohort of nine patients, to determine the localization of these cathepsins in relation to the CSC subpopulations. NanoString mRNA analysis and Western Blotting (WB) were used to examine the transcript and protein expression of these cathepsins, respectively. Enzyme activity assays were utilized to determine their functional activity. Data acquired from counting of cells staining positively of the cathepsins on the DAB IHC-stained slides and from Nanostring mRNA analysis were subjected to statistical analyses to determine significance.

Results

DAB IHC staining demonstrated expression of cathepsins B, D and G within LMCA. IF IHC staining demonstrated the expression of both cathepsin B and cathepsin D by the OCT4⁻ cells within the tumor nests and the OCT4⁺ CSC subpopulation within the peritumoral stroma. NanoString mRNA analysis showed significantly greater transcript expression of cathepsin B and cathepsin D, compared to cathepsin G. WB confirmed expression of cathepsin B and cathepsin D proteins, while cathepsin G was below detectable levels. Enzyme activity assays showed functional activity of cathepsin B and cathepsin D.

Conclusion

Our study demonstrated novel finding of the expression of cathepsin B, cathepsin D, and possibly cathepsin G by the putative CSC subpopulations within LMCA.

Exome and transcriptome sequencing identifies loss of PDLIM2 in metastatic colorectal cancers

Background

Understanding the genomic determinants associated with metastasis in colorectal cancers (CRCs) provides crucial clues for improving patient care.

Patients and methods

In this study, we performed whole-exome sequencing as well as RNA sequencing analyses on five pairs of primary and liver metastasized samples from CRC patients together with blood/normal control samples for each pair.

Results

We identified genomic deletions in the region of 8p21-23 (q value <0.01) from analysis of recurrent regions with copy number variations in both primary and matched metastatic lesions. Consistent with this result, we found significantly decreased expression levels of all 12 genes (ADAMDEC1, C8orf80, CLDN23, EPHX2, GFRA2, NEFL, NEFM, PDLIM2, PTK2B, SCARA5, SLC18A1 and STMN4) located within this region (adjusted P<0.01). Notably, the mRNA levels of PDLIM2, a key regulator of well-known cancer-associated genes including the proto-oncogene c-MYC, an early response gene IER3, and regulators of apoptosis such as BCL2, FAS, and FASLG, were highly downregulated in tumors compared to normal tissues.

Conclusion

Taken together, our findings uncovered various genomic alterations potentially leading to metastasis in CRC and provide important insights into the development of potential therapeutic targets for preventing metastatic progression of CRC.

The adaptation of colorectal cancer cells when forming metastases in the liver: expression of associated genes and pathways in a mouse model

Background

Colorectal cancer (CRC) is the second leading cause of cancer-related death in men and women. Systemic disease with metastatic spread to distant sites such as the liver reduces the survival rate considerably. The aim of this study was to investigate the changes in gene expression that occur on invasion and expansion of CRC cells when forming metastases in the liver.

Methods

The livers of syngeneic C57BL/6NCrl mice were inoculated with 1 million CRC cells (CMT-93) via the portal vein, leading to the stable formation of metastases within 4 weeks. RNA sequencing performed on the Illumina platform was employed to evaluate the expression profiles of more than 14,000 genes, utilizing the RNA of the cell line cells and liver metastases as well as from corresponding tumour-free liver.

Results

A total of 3329 differentially expressed genes (DEGs) were identified when cultured CMT-93 cells propagated as metastases in the liver. Hierarchical clustering on heat maps demonstrated the clear changes in gene expression of CMT-93 cells on propagation in the liver. Gene ontology analysis determined inflammation, angiogenesis, and signal transduction as the top three relevant biological processes involved. Using a selection list, matrix metallopeptidases 2, 7, and 9, wnt inhibitory factor, and chemokine receptor 4 were the top five significantly dysregulated genes.

Conclusion

Bioinformatics assists in elucidating the factors and processes involved in CRC liver metastasis. Our results support the notion of an invasion-metastasis cascade involving CRC cells forming metastases on successful invasion and expansion within the liver. Furthermore, we identified a gene expression signature correlating strongly with invasiveness and migration. Our findings may guide future research on novel therapeutic targets in the treatment of CRC liver metastasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3342-1) contains supplementary material, which is available to authorized users.

Cadherin-12 enhances proliferation in colorectal cancer cells and increases progression by promoting EMT

Cadherin-12 (CDH12) is a subtype of N-cadherin family. In this study, we investigated the expression of CDH12 and the role of CDH12 in prognosis of colorectal cancer (CRC) patients. In addition, we observed the influence of CDH12 on proliferation and progression of CRC cell lines. By using immunohistochemical staining, we analyzed CRC samples and adjacent non-tumor tissues collected from 78 patients who underwent laparoscopic surgery in Shanghai Minimally Invasive Center, China. Statistical analyses were used to analyze relationship between CDH12 and tumor features. Kaplan-Meier method was used to analyze patients' survival. Proliferation ability of CRC cells was tested by CCK-8 assay, and transwell assays were performed to detect migration and invasion ability. Western blot assay was performed to investigate epithelial-mesenchymal transition (EMT) variants. We found that expression of CDH12 in tumor tissue was higher than in adjacent normal tissue. High expression of CDH12 was associated with tumor invasion depth and predicts poor prognosis of CRC patients. Ectopic/repressing expression of CDH12 increased/decreased the proliferation and migration ability of CRC cells. CDH12 is able to increase cancer cell migration and invasion via promoting EMT by targeting transcriptional factor Snail. These findings may conclude that CDH12 may act as a predictor in CRC patients' prognosis and an oncogene in CRC cell proliferation and migration. CDH12 may influence CRC cell progression through promoting EMT by targeting Snail. In addition, CDH12 is promoted by MCP1 through induction of MCPIP.

Downregulation of microRNA-409-3p promotes aggressiveness and metastasis in colorectal cancer: an indication for personalized medicine

BACKGROUND

MicroRNAs play an essential role in colorectal cancer development and progression. Aberrant miR-409-3p expression has been reported in several cancers. However, the clinical significance and functions of miR-409-3p in human CRC were not entirely clear.

METHODS

miR-409-3p expression levels were determined in 45 pairs of primary CRC and their corresponding adjacent non-tumor tissues by qPCR. The effects of ectopic expression of miR-409-3p on CRC cells proliferation, wound healing, metastasis were investigated by CCK-8, transwell assay and peritoneal spreading nude mice model.

RESULTS

Statistical analysis of clinical cases revealed that low miR-409-3p expression had inclinations towards lager tumor size and local invasion. Ectopic expression of miRNA mimics suggested that miR-409-3p could inhibits the abilities of proliferation, wound healing, metastasis and invasion in CRC cells. Notably, we found the NLK could be a potential target of miR-409-3p.

CONCLUSION

Our results suggest that miR-409-3p functions as a tumor suppressor by inhibiting the development and metastasis of CRC, suggesting that miR-409-3p is expected to become a new diagnostic marker and a new target of the treatment of CRC.

E2A suppresses invasion and migration by targeting YAP in colorectal cancer cells

Background

E2A gene, which encodes two basic helix–loop–helix (bHLH) transcription factors E12 and E47, has been identified as regulator of B lymphoid hematopoiesis and suppressor of lymphoma. E47 protein was found to decrease E-cadherin expression and induce epithelial-mesenchymal transition (EMT). However, the role of E2A in colorectal cancer (CRC) metastasis is still elusive.

Methods

qRT-PCR and semi-qRT-PCR were performed to determine mRNA level of E2A in CRC specimens and colorectal cancer cells. RNAi was employed to downregulate E2A expression and subsequent protein level change was evaluated by immunoblot. Cell invasion and migration capacity were detected by transwell assay using cell culture inserts with or without basement membrane matrix, respectively.

Results

E2A expression was decreased in metastatic CRC tissues. Invasion and migration assays showed downregulation of E2A increased metastatic capacity of CRC cells while forced expression of E12 or E47 could offset this effect. Both E12 and E47 suppressed EMT induced by E2A downregulation. Moreover, Yes-Associated Protein (YAP) was a downstream target of E2A and suppression of YAP inhibited the pro-migration/invasion of E2A deficiency.

Conclusion

Our results suggest that E2A suppresses CRC cell metastasis, at least partially if not all, by inhibiting YAP expression.

miR-320a suppresses colorectal cancer progression by targeting Rac1

MicroRNAs (miRNAs) have emerged as critical epigenetic regulators involved in cancer progression. miR-320a has been identified to be a novel tumour suppressive miRNA in colorectal cancer (CRC). However, the detailed molecular mechanisms are not fully understood. Here, we reported that miR-320a inversely associated with CRC aggressiveness in both cell lines and clinical specimens. Functional studies demonstrated that miR-320a significantly decreased the capability of cell migration/invasion and induced G0/G1 growth arrest in vitro and in vivo. Furthermore, Rac1 was identified as one of the direct downstream targets of miR-320a and miR-320a specifically binds to the conserved 8-mer at position 1140-1147 of Rac1 3'-untranslated region to regulate Rac1 protein expression. Over-expression of miR-320a in SW620 cells inhibited Rac1 expression, whereas reduction of miR-320a by anti-miR-320a in SW480 cells enhanced Rac1 expression. Re-expression of Rac1 in the SW620/miR-320a cells restored the cell migration/invasion inhibited by miR-320a, whereas knockdown of Rac1 in the SW480/anti-miR-320a cells repressed these cellular functions elevated by anti-miR-320a. Conclusively, our results demonstrate that miR-320a functions as a tumour-suppressive miRNA through targeting Rac1 in CRC.

The liver prometastatic reaction of cancer patients: implications for microenvironment-dependent colon cancer gene regulation

Colon cancer frequently metastasizes to the liver but the genetic and phenotypic properties of specific cancer cells able to implant and grow in this organ have not yet been established. The contribution of the patient's genetic, physiologic and pathologic backgrounds to the incidence and development of hepatic colon cancer metastases is also presently misunderstood. At a transcriptional level, hepatic metastasis development is in part associated with marked changes in gene expression of colon cancer cells that may originate in the primary tumor. Other changes occur in the liver and are regulated by hepatic cells, which represent the new microenvironment for metastatic colon cancer cells. However, hepatic parenchymal and non-parenchymal cell functions are also affected by both tumor-derived factors and systemic host factors, which suggests that the hepatic metastasis microenvironment is a functional linkage between the hepatic pathophysiology of the colon cancer patient and the biology of its cancer cells. Therefore, together with metastasis-related gene profiles suggesting the existence of liver metastasis potential in primary tumors, new biomarkers of the prometastatic microenvironment supported by the liver reaction to colon cancer factors may be helpful for the individual assessment of hepatic metastasis risk in colon cancer patients. In addition, knowledge on hepatic metastasis gene regulation by the hepatic microenvironment may open multiple opportunities for therapeutic intervention during colon cancer metastasis at both subclinical and advanced stages.

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.

Targeting the extracellular signature of metastatic colorectal cancers

BACKGROUND

Colorectal cancer is a leading cause of tumor death, a consequence primarily of the spreading of malignant cells to liver and lung. Despite a range of interventions for liver metastases, the present knowledge of few specific molecular targets may contribute to late diagnosis and poorly effective therapy.

OBJECTIVE

To review the most innovative methodology employed to profile the signature(s) of metastatic colorectal cancer (mCRC) and to address diagnostic/therapeutic agents.

METHODS

A broad range Medline search was conducted, with particular attention to the search terms 'liver metastasis signature', in combination with 'targeting' and 'nanotechnology'.

RESULTS/CONCLUSIONS

Studies aimed at the discovery of molecular signatures of cancers and metastasis are ongoing; the future of cancer/metastasis targeting is nanoparticle-mediated drug delivery.