Tumor invasion and host extracellular matrix

Hepatocellular Carcinoma (HCC) Metastasis to the Diaphragm Muscle: A Systematic Review and Meta-Analysis of Case Reports

The purpose of this study was to conduct a systematic review and meta-analysis of case reports presenting HCC spread to the diaphragm muscle and to determine possible risk factors for this condition. An extensive literature search was performed using the following electronic databases: MEDLINE, CINAHL, ScienceDirect, Google Scholar, and DOAJ. A total of 18 articles describing 27 hepatocellular carcinoma patients were included in this review. The presence of HCC cells in the superior liver segment is strongly associated with metastases to the diaphragm. Among the two types of diaphragm involvement by HCC cells, diaphragm infiltration occurs much more frequently than diaphragm adhesion. However, an HCC nodule in the 8th liver segment and a higher number of liver segments involved by HCC cells predispose patients to diaphragm adhesion. Hepatitis B is a risk factor for diaphragm metastases in recurrent HCC. The tumor diameter is not associated with HCC spread to the diaphragm muscle. We did not find specific symptoms reported by patients that could indicate HCC metastasis to the diaphragm muscle. The presence of hepatitis B and the localization of HCC cells in superior liver segments, especially in the 8th liver segment, should be take into consideration in the diagnostic process.

Skeletal muscle metastasis from extrahepatic cholangiocarcinoma: A case report and literature review

Background

Cholangiocarcinoma (CCA) is a type of malignant tumor that arises from the epithelium of the bile ducts. According to anatomical location, CCA can be classified as intrahepatic (ICC), perihilar (PCC), or extrahepatic (ECC). CCA can invade and metastasize to other tissues in various ways, but distal skeletal muscle metastasis (SMM) is extremely rare. There are several reports on SMM from ICC or PCC, but SMM from ECC has not yet been reported.

Case presentation

A 71-year-old woman was diagnosed with ECC, for which she underwent pancreatoduodenectomy and partial hepatectomy. Nine months after surgery, she was re-admitted to the hospital complaining of a rapidly growing mass on her right thigh with progressive lower extremity edema. Magnetic resonance imaging of the right thigh showed two masses with iso-signal intensity on T1-weighted images and hyper-intensity on T2-weighted images compared with the surrounding muscles. Pathological examination of the fine-needle biopsy specimen revealed that it was similar to the previously detected ECC, and the diagnosis was metastasis of ECC. The patient was treated with opioid analgesics and died of systemic failure three months later.

Conclusion

SMM should be considered during the follow-up period despite its low incidence, and perineural invasion may be an essential pathway of distant metastasis in CCA.

Characterisation of 3D Bioprinted Human Breast Cancer Model for In Vitro Drug and Metabolic Targeting

Monolayer cultures, the less standard three-dimensional (3D) culturing systems, and xenografts are the main tools used in current basic and drug development studies of cancer research. The aim of biofabrication is to design and construct a more representative in vivo 3D environment, replacing two-dimensional (2D) cell cultures. Here, we aim to provide a complex comparative analysis of 2D and 3D spheroid culturing, and 3D bioprinted and xenografted breast cancer models. We established a protocol to produce alginate-based hydrogel bioink for 3D bioprinting and the long-term culturing of tumour cells in vitro. Cell proliferation and tumourigenicity were assessed with various tests. Additionally, the results of rapamycin, doxycycline and doxorubicin monotreatments and combinations were also compared. The sensitivity and protein expression profile of 3D bioprinted tissue-mimetic scaffolds showed the highest similarity to the less drug-sensitive xenograft models. Several metabolic protein expressions were examined, and the in situ tissue heterogeneity representing the characteristics of human breast cancers was also verified in 3D bioprinted and cultured tissue-mimetic structures. Our results provide additional steps in the direction of representing in vivo 3D situations in in vitro studies. Future use of these models could help to reduce the number of animal experiments and increase the success rate of clinical phase trials.

Muscular Metastasis of Hepatocellular Carcinoma: Case Report and Literature Review

There are few case reports of hepatocellular carcinoma (HCC) metastasis to the skeletal muscle. A 78-year-old man developed a mass in the right shoulder. Washout of contrast medium during contrast-enhanced ultrasonography (CEUS) in both the primary HCC and the metastatic site was detected. Several nodules were scattered throughout the liver on an autopsy. In addition, the moderately differentiated HCC had metastasized to the right teres major muscle. Rare muscular metastasis should be considered if a hepatic tumor is moderately or poorly differentiated HCC. Early washout during CEUS is consistent with a pathological diagnosis of moderately or poorly differentiated HCC.

SYDE1 Acts as an Oncogene in Glioma and has Diagnostic and Prognostic Values

Objectives: Gliomas remain one of serious public health problems worldwide which demand further and deeper investigation. The aim of this study was to explore the association between synapse defective protein 1 homolog 1 (SYDE1) and gliomas via public database analysis and in vitro validation to determine the potential diagnostic and prognostic values. Methods and Results: Compared with healthy brain tissues, there was a significant increase in SYDE1 expression in glioma tissues. Additionally, SYDE1 exhibited higher expression levels in glioma patients with unfavorable clinicopathological factors. In vitro knockdown of SYDE1 in glioma cell lines A172 inhibited their migrative and invasive ability but not the proliferative ability. GO and KEGG pathway analysis of the top 100 genes coexpressed with SYDE1 showed enrichments of tumor-associated terms. Further bioinformatic analysis revealed that the SNHG16/hsa-miR-520e/SYDE1 axis might be involved in glioma development. Conclusions: SYDE1 is expressed at higher levels in gliomas than in healthy brains, and can promote metastasis and invasion but not proliferation of gliomas. Furthermore, SYDE1 has values in the diagnosis and prognosis prediction of gliomas.

Acquired radioresistance in cancer associated fibroblasts is concomitant with enhanced antioxidant potential and DNA repair capacity

Background

Cancer-associated fibroblasts (CAFs) are a major component of the cancer stroma, and their response to therapeutic treatments likely impacts the outcome. We tested the hypothesis that CAFs develop unique characteristics that enhance their resistance to ionizing radiation.

Methods

CAFs were generated through intimate coculture of normal human fibroblasts of skin or lung origin with various human cancer cell types using permeable microporous membrane inserts. Fibroblasts and cancer cells are grown intimately, yet separately, on either side of the insert’s membrane for extended times to generate activated fibroblast populations highly enriched in CAFs.

Results

The generated CAFs exhibited a decrease in Caveolin-1 protein expression levels, a CAF biomarker, which was further enhanced when the coculture was maintained under in-vivo-like oxygen tension conditions. The level of p21^Waf1 was also attenuated, a characteristic also associated with accelerated tumor growth. Furthermore, the generated CAFs experienced perturbations in their redox environment as demonstrated by increases in protein carbonylation, mitochondrial superoxide anion levels, and modulation of the activity of the antioxidants, manganese superoxide dismutase and catalase. Propagation of the isolated CAFs for 25 population doublings was associated with enhanced genomic instability and a decrease in expression of the senescence markers β-galactosidase and p16^INK4a. With relevance to radiotherapeutic treatments, CAFs in coculture with cancer cells of diverse origins (breast, brain, lung, and prostate) were resistant to the clastogenic effects of ¹³⁷Cs γ rays compared to naïve fibroblasts. Addition of repair inhibitors of single- or double-stranded DNA breaks attenuated the resistance of CAFs to the clastogenic effects of γ rays, supporting a role for increased ability to repair DNA damage in CAF radioresistance.

Conclusions

This study reveals that CAFs are radioresistant and experience significant changes in indices of oxidative metabolism. The CAFs that survive radiation treatment likely modulate the fate of the associated cancer cells. Identifying them together with their mode of communication with cancer cells, and eradicating them, particularly when they may exist at the margin of the radiotherapy planning target volume, may improve the efficacy of cancer treatments.

Novel histopathological classification of meningiomas based on dural invasion

AIMS

Histological invasion into the adjacent brain parenchyma is frequently investigated in meningioma because it is an important morphological criterion for grade II meningioma according to the 2016 WHO classification. However, few studies have focused on dural invasion of meningiomas. Herein, we propose a novel histopathological classification based on dural invasion of meningiomas.

METHODS

Forty-nine cases with WHO grade I meningiomas who underwent Simpson grade I removal were collected. After the meningeal layer (ML) and periosteal layer (PL) of dura mater were visualised by Masson's trichrome stain, we evaluated the depth (to the ML and PL) and the patterns (1, expanding; 2, infiltrating) of dural invasion of meningiomas using serial paraffin sections. Invasion-associated markers, including Ki-67, matrix metalloproteinase (MMP)-1, MMP-9 and MMP-13, aquaporin 1 and Na-K-2Cl cotransporter, were quantitatively analysed by immunohistochemistry.

RESULTS

Thirty-five cases (71.4%) showed the dural invasion. In 27 of these 35 cases (77.1%), dural invasion was localised in ML. Type 1 (expanding type) and type 2 (infiltrating type) invasions were observed in 23 and 12 cases, respectively. The recurrence rate in cases with type 2 invasion was significantly higher than that in cases with type 1 invasion. The percentage of MMP-1-positive tumour cells was also significantly higher in cases with dural invasion than those without, suggesting involvement of MMP-1 in dural invasion.

CONCLUSIONS

We quantitatively evaluated the depth and patterns of dural invasion in meningiomas. The patterns of dural invasion were associated with meningioma recurrence.

Novel quantitative signature of tumor stromal architecture: polarized light imaging differentiates between myxoid and sclerotic human breast cancer stroma

As a leading cause of death in women, breast cancer is a global health concern for which personalized therapy remains largely unrealized, resulting in over- or under-treatment. Recently, tumor stroma has been shown to carry important prognostic information, both in its relative abundance and morphology, but its current assessment methods are few and suboptimal. Herein, we present a novel stromal architecture signature (SAS) methodology based on polarized light imaging that quantifies patterns of tumor connective tissue. We demonstrate its ability to differentiate between myxoid and sclerotic stroma, two pathology-derived categories associated with significantly different patient outcomes. The results demonstrate a 97% sensitivity and 88% specificity for myxoid stroma identification in a pilot study of 102 regions of interest from human invasive ductal carcinoma breast cancer surgical specimens (20 patients). Additionally, the SAS numerical score is indicative of the wide range of stromal characteristics within these binary classes and highlights ambiguous mixed-morphology regions prone to misclassification. The enabling polarized light microscopy technique is inexpensive, fast, fully automatable, applicable to fresh or embedded tissue without the need for staining and thus potentially translatable into research and/or clinical settings. The SAS metric yields quantifiable and objective stromal characterization with promise for prognosis in many types of cancers beyond breast carcinoma, enabling researchers and clinicians to further investigate the emerging and important role of stromal architectural patterns in solid tumors.

Zyxin (ZYX) promotes invasion and acts as a biomarker for aggressive phenotypes of human glioblastoma multiforme

Glioblastoma multiforme (GBM) is characterized by highly invasive growth, which leads to extensive infiltration and makes complete tumor excision difficult. Since cytoskeleton proteins are related to leading processes and cell motility, and through analysis of public GBM databases, we determined that an actin-interacting protein, zyxin (ZYX), may involved in GBM invasion. Our own glioma cohort as well as the cancer genome atlas (TCGA), Rembrandt, and Gravendeel databases consistently showed that increased ZYX expression was related to tumor progression and poor prognosis of glioma patients. In vitro and in vivo experiments further confirmed the oncogenic roles of ZYX and demonstrated the role of ZYX in GBM invasive growth. Moreover, RNA-seq and mass-spectrum data from GBM cells with or without ZYX revealed that stathmin 1 (STMN1) was a potential target of ZYX. Subsequently, we found that both mRNA and protein levels of STMN1 were positively regulated by ZYX. Functionally, STMN1 not only promoted invasion of GBM cells but also rescued the invasion repression caused by ZYX loss. Taken together, our results indicate that high ZYX expression was associated with worse prognosis and highlighted that the ZYX-STMN1 axis might be a potential therapeutic target for GBM.

The Role of Collagen XVII in Cancer: Squamous Cell Carcinoma and Beyond

Alterations in the extracellular matrix (ECM) likely facilitate the first steps of cancer cell metastasis and supports tumor progression. Recent data has demonstrated that alterations in collagen XVII (BP180), a transmembrane protein and structural component of the ECM, can have profound effects on cancer invasiveness. Collagen XVII is a homotrimer of three α1 (XVII) chains. Its intracellular domain contains binding sites for plectin, integrin β4, and BP230, while the extracellular domain facilitates interactions between the cell and the ECM. Collagen XVII and its shed ectodomain have been implicated in cell motility and adhesion and are believed to promote tumor development and invasion. A strong association of collagen XVII ectodomain shedding and tumor invasiveness occurs in squamous cell carcinoma (SCC). Aberrant expression of collagen XVII has been reported in many epithelial cancers, ranging from squamous cell carcinoma to colon, pancreatic, mammary, and ovarian carcinoma. Thus, in this review, we focus on collagen XVII's role in neoplasia and tumorigenesis. Lastly, we discuss the importance of targeting collagen XVII and its ectodomain shedding as a novel strategy to curb tumor growth and reduce metastatic potential.

1-(5-Bromo-2-hydroxy-4-methoxyphenyl)ethanone [SE1] Inhibits MMP-9 Expression by Regulating NF-κB and MAPKs Signaling Pathways in HT1080 Human Fibrosarcoma Cells

Hippocampus is a traditional medicine in China, which can be used for treating tumors, aging, fatigue, thrombosis, inflammation, hypertension, prostatic hyperplasia, and other diseases. 1-(5-Bromo-2-hydroxy-4-methoxyphenyl)ethanone [SE1] from seahorse (Hippocampus kuda Bleeler) has been shown to suppress proinflammatory responses. In the present study, SE1 potently inhibited gelatin digestion by MMP-9 induced by phorbol 12-myristate 13-acetate (PMA) and migration of human fibrosarcoma HT1080 cells in dose-dependent manner. Moreover, western blot analysis and immunofluorescence analysis have been studied on MAPKs (ERK1/2, p38 kinase and JNK) and NF-κB (p65 and IκB), which refer to the clear molecular mechanism. The results indicated that SE1 significantly suppressed the phosphorylation of mitogen-activated protein kinases (MAPK: p38 kinase and JNK) and NF-κB. Finally, molecular docking result showed SE1 interacts with TYR245 and HIS226 of MMP-9 by hydrogen bond and Pi-Pi bond to suppress MMP-9 activity. This data suggested that the SE1 may possess therapeutic and preventive potential for the treatment of MMP-9 related disorders.

Identification of COL1A1 as an invasion‑related gene in malignant astrocytoma

Malignant astrocytoma (MA) is the most common and severe type of brain tumor. A greater understanding of the underlying mechanisms responsible for the development of MA would be beneficial for the development of targeted molecular therapies. In the present study, the upregulated differentially expressed genes (DEGs) in MA were obtained from the Gene Expression Omnibus database using R/Bioconductor software. DEGs in different World Health Organization classifications were compared using the Venny tool and 15 genes, including collagen type I α1 chain (COL1A1) and laminin subunit γ1 (LAMC1), were revealed to be involved in the malignant progression of MA. In addition, the upregulated DEGs in MA were evaluated using functional annotations of Gene Ontology and Kyoto Encyclopedia of Genes and Genomes with the Database for Annotation, Visualization, and Integrated Discovery tool. The results indicated that invasion-associated enrichment was observed in 'extracellular matrix' (ECM), 'cell adhesion' and 'phosphoinositide 3-kinase-protein kinase B signaling pathway'. Subsequently, the analysis of the protein-protein interactions was performed using STRING and Cytoscape software, which revealed that the ECM component was the invasion-associated module and its corresponding genes included COL1A1, LAMC1 and fibronectin 1. Finally, survival Kaplan-Meier estimate was conducted using cBioportal online, which demonstrated that COL1A1 expression affected the survival of and recurrence in patients with MA. Moreover, the results of in vitro Transwell assay and western blot analysis revealed that the depleted levels of COL1A1 also decreased the expression of several proteins associated with cell invasion, including phosphorylated-signal transducer and activator of transcription 3, matrix metalloproteinase (MMP)-2, MMP-9 and nuclear factor-κB. On the whole, the present study identified the invasion-related target genes and the associated potential pathways in MA. The results indicated that COL1A1 may be a candidate biomarker for the prognosis and treatment of MA.

Solitary biceps muscle metastasis from breast cancer

Although direct muscle invasion by carcinoma is well recognised, skeletal muscle metastases are rare. Breast cancer very rarely metastasises to skeletal muscles. We present a case of breast cancer that metastasised to the biceps muscle. The woman developed breast cancer in 1990 and then developed axillary subcutaneous metastasis in 2001. In 2015, she presented with pain in the left forearm extending to the hand. Initial imaging showed no abnormalities, but the positron emission tomography-CT scanning revealed a hot spot in the left biceps muscle. Additionally, the nerve conduction study showed feature of carpal tunnel syndrome. The hot spot was deemed inconclusive in the view of normal CT and MRI scans, and the patient was treated with carpal tunnel decompression. A few months later, the patient developed a lump in the left biceps muscle, which appeared to be a metastatic lesion from her primary breast cancer. The patient was treated with radiotherapy and responded satisfactorily.

Exosomes: The Link between GPCR Activation and Metastatic Potential?

The activation of G-Protein Coupled Receptors (GPCRs) by their respective ligands initiates a cascade of multiple signaling processes within the cell, regulating growth, metabolism and other essential cellular functions. Dysregulation and aberrant expression of these GPCRs and their subsequent signaling cascades are associated with many different types of pathologies, including cancer. The main life threatening complication in patients diagnosed with cancer is the dissemination of cells from the primary tumor to distant vital organs within the body, metastasis. Communication between the primary tumor, immune system, and the site of future metastasis are some of the key events in the early stages of metastasis. It has been postulated that the communication is mediated by nanovesicles that, under non-pathological conditions, are released by normal cells to relay signals to other cells in the body. These nanovesicles are called exosomes, and are utilized by the tumor cell to influence changes within the recipient cell, such as bone marrow progenitor cells, and cells within the site of future metastatic growth, in order to prepare the site for colonization. Tumor cells have been shown to release an increased number of exosomes when compared to their normal cell counterpart. Exosome production and release are regulated by proteins involved in localization, degradation and size of the multivesicular body, whose function may be altered within cancer cells, resulting in the release of an increased number of these vesicles. This review investigates the possibility of GPCR signaling cascades acting as the upstream activator of proteins involved in exosome production and release, linking a commonly targeted trans-membrane protein class with cellular communication utilized by tumor cells in early stages of metastasis.

RNA interference targeting human integrin α6 suppresses the metastasis potential of hepatocellular carcinoma cells

Background

Increased metastasis has been proved to be associated with a poor prognosis for hepatocellular carcinoma (HCC). There are higher-level expressions of integrin α6 in the tissues of HCC patients with a higher fatality rate. The aim of this study is to investigate the effect of short hairpin RNA (shRNA) silencing integrin α6 expression on the proliferation and metastasis in HCC cell lines.

Methods

Two human HCC cell lines, HepG2 and Bel-7402 were transfected with shRNA targeting human integrin α6. Protein and mRNA expression level were determined by western blot and real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to detect the transfected efficacy. The metastasis potential of HCC cells was evaluated by their proliferation, adhesion and invasion abilities. Cell proliferation was measured by MTT assay. Adhesion ability was measured by adhesion and spreading assays. The expression of matrix metalloproteinases (MMPs) was measured by qRT-PCR. The potential of invasion was measured by qRT-PCR and Transwell chamber assay. PI3K inhibitor LY294002 was used to explore the signal pathways of integrin α6 in HCC cells.

Results

Western blot and qRT-PCR detection showed that over 75% of integrin α6 expression in HCC cells was through knockdown by shRNA. Proliferation, adhesion, spreading and invasion of HepG2 and Bel-7402 cells were dramatically decreased in cells transfected with shRNA compared to the control cells. P-ERK and p-AKT were reduced by shRNA targeting integrin α6 and PI3K inhibitor LY294002.

Conclusion

Knockdown integrin α6 can inhibit the proliferation and metastasis of HCC cells through PI3K/ARK and MAPK/ERK signal pathways by shRNA in vitro. Integrin α6 can mediate the metastasis potential, and can be used as a candidate target for therapy in HCC resulting in improved patients’ survival.

Urokinase Plasminogen Activator Receptor and Soluble Matrix Metalloproteinase-9 in Acute Myeloid Leukemia Patients: A Possible Relation to Disease Invasion

Extracellular proteolytic enzymes of the urokinase-type plasminogen activator (uPA) and metalloproteinase (MMP) family play a crucial role in the matrix degradation and tissue remodeling process characteristic of malignant disorders. The receptor for urokinase plasminogen activator (uPAR) serves to localize and intensify the action of UPA and is expressed on the surface of malignant cells. Although the biological significance of MMP-9 and soluble urokinase receptor in growth and progression of lymphoid neoplasm is understood, its clinical significance in acute myeloid leukemia (AML) has not been fully elucidated. In this study, we determined the levels of soluble urokinase-type plasminogen activator receptor (suPAR), cellular uPAR and sMMP-9 in 43 newly diagnosed AML patients at diagnosis, before chemotherapy, and also studied 10 normal subjects served as a control group. After chemotherapy suPAR and MMP-9 were determined at remission and relapse. The levels of suPAR, cellular PAR were significantly higher (P= 0.001, 0.001) and MMP-9 was significantly lower (P=0.001) in AML patients at diagnosis as compared to controls. suPAR and MMP-9 levels were significantly lower in AML patients who achieved complete remission (CR) as compared to those who did not (P= 0.001 for both). Levels of suPAR and MMP-9 were significantly correlated to peripheral blood blast cells (r= 0.88, P= 0.001; r= 0.65, P= 0.001, respectively) and blast cell distribution ratio (BCDR, r= 0.84, P= 0.001; r=65, P= 0.001, respectively). suPAR, cellular PAR and MMP-9 were significantly higher in patients with extramedullary infiltration as compared with those without (P= 0.001, 0.001, <0.05). The suPAR, cellular uPAR, and MMP-9 levels were uneven in AML FAB subtypes being highest in M5(P<0.05 for all). MMP-9 and suPAR levels were correlated with the disease status. In AML survivors, MMP-9, cellular uPAR and suPAR were significantly lower as compared to non-survivors (P= 0.001 for all). In conclusion, MMP-9 and su PAR levels might be used as a marker for disease activity and may contribute to blast cell dissemination. MMP-9 and suPAR may be target molecules in the strategy of treatment of AML.

Characterization of invading glioma cells using molecular analysis of leading-edge tissue

OBJECTIVE

We have introduced a method of characterization of invading glioma cells by using molecular analysis of marginal invading tumor cells and molecular profiles of glioma tumor margin.

METHODS

Each of tumor core and marginal tissues was obtained in 22 glioma patients. Tumor core cells and marginal cells from each glial tumor were collected by laser capture microdissection or intraoperative microdissection under the operating microscope. Expression of MMP-2, MMP-9, CD44 and RHAMM mRNA by invading glioma cells compared with tumor core was confirmed by realtime-PCR of twenty-four glioma specimens. Clinical data also were reviewed for invasion and recurrence pattern of the gliomas radiologically and invasive rim pattern microscopically.

RESULTS

Overall results of the molecular analysis showed that relative overexpression of MMP-2, MMP-9 and RHAMM were noted at the invasive edge of human glioma specimens comparing to the tumor core but CD44 was highly expressed in the tumor core comparing to the margin. High marginal expression of MMP-2 and MMP-9 were noted in poorly ill-defined margin on the pathological finding. High marginal expression of CD44 and MMP-2 were demonstrated in the midline cross group on the radiological review, and that of RHAMM and MMP-2 were showed in the aggressive recurrence group. High expression of MMP-2 seems to be involved in the various invasion-related phenomenons.

CONCLUSION

Up-regulation of MMP-2, MMP-9, CD44 and RHAMM was noted in invasive edge of gliomas according to the various clinical situations.

Detection of distant metastasis to skeletal muscle by 18F-FDG-PET in a case of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma is a rare malignancy that originates from the epithelial cells of the intrahepatic bile ducts. Intrahepatic cholangiocarcinoma can metastasize in lymphatic chains, including the hepatoduodenal ligament, and it often invades adjacent organs or metastasizes to other visceral organs such as the lungs, bones, adrenal glands, and brain. However, distant skeletal muscle metastasis is very rare. Moreover, a metastatic skeletal muscle tumor rarely shows specific symptoms, making it difficult to identify in a routine examination. A 45-year-old man with a chief complaint of right upper quadrant abdominal pain was admitted to our hospital. Abdominal ultrasound and computed tomography with contrast enhancement showed a malignant mass in the right hepatic lobe, and 2-[¹⁸F] fluoro-2-deoxy-D-glucose positron-emission tomography revealed distant skeletal muscle metastases in the thorax and buttock. The patient underwent an ultrasound-guided percutaneous needle biopsy for the metastatic low-echo masses in the skeletal muscle.

Metastasis suppressor genes at the interface between the environment and tumor cell growth

The molecular mechanisms and genetic programs required for cancer metastasis are sometimes overlapping, but components are clearly distinct from those promoting growth of a primary tumor. Every sequential, rate-limiting step in the sequence of events leading to metastasis requires coordinated expression of multiple genes, necessary signaling events, and favorable environmental conditions or the ability to escape negative selection pressures. Metastasis suppressors are molecules that inhibit the process of metastasis without preventing growth of the primary tumor. The cellular processes regulated by metastasis suppressors are diverse and function at every step in the metastatic cascade. As we gain knowledge into the molecular mechanisms of metastasis suppressors and cofactors with which they interact, we learn more about the process, including appreciation that some are potential targets for therapy of metastasis, the most lethal aspect of cancer. Until now, metastasis suppressors have been described largely by their function. With greater appreciation of their biochemical mechanisms of action, the importance of context is increasingly recognized especially since tumor cells exist in myriad microenvironments. In this chapter, we assemble the evidence that selected molecules are indeed suppressors of metastasis, collate the data defining the biochemical mechanisms of action, and glean insights regarding how metastasis suppressors regulate tumor cell communication to-from microenvironments.

Metastatic carcinoma to subcutaneous tissue and skeletal muscle: clinicopathological features in 11 cases

OBJECTIVE

Metastatic carcinoma to subcutaneous tissue or skeletal muscle is relatively rare. The present study aimed to clarify the clinicopathological features for confirming the diagnosis as soft tissue metastasis and determining the primary site.

METHODS

We reviewed records of 11 patients with soft tissue metastasis who were in our institution from 1996 to 2009.

RESULTS

In 9 of 10 patients who underwent magnetic resonance imaging, findings consisted of poorly circumscribed high-intensity lesions around the tumor on T2-weighted images, irregular peritumoral enhancement and poorly enhanced lesions at the center of the tumor on T1-weighted images. Systematic immunohistochemical examination was more valuable for diagnosing as soft tissue metastasis and confirming the primary site. The expression patterns of cytokeratins 7 and 20 and tissue-specific antibodies such as thyroid transcription factor-1, MUC5AC and CDX2 were useful diagnostic markers. The primary site could be determined in five patients with cytokeratin 7/20 immunophenotype and positivity for tissue-specific antibodies. In four cases, determination of the primary site finally became possible by comparison with the histological findings of operative specimens in past carcinoma and/or in consideration of radiological findings and the results of cytokeratin 7/20 phenotyping.

CONCLUSIONS

Systematic immunohistochemical examination is helpful for confirmation of the primary origin in soft tissue metastasis of carcinoma in addition to clinical information such as the history and condition of past carcinoma, radiological findings and comparison between the histology of biopsy specimens and past carcinoma.

Chemical Tumor Biology of Heparan Sulfate Proteoglycans

Heparan sulfate proteoglycans (HSPGs) play vital roles in every step of tumor progression allowing cancer cells to proliferate, escape from immune response, invade neighboring tissues, and metastasize to distal sites away from the primary site. Several cancers including breast, lung, brain, pancreatic, skin, and colorectal cancers show aberrant modulation of several key HS biosynthetic enzymes such as 3-O Sulfotransferase and 6-O Sulfotransferase, and also catabolic enzymes such as HSulf-1, HSulf-2 and heparanase. The resulting tumor specific HS fine structures assist cancer cells to breakdown ECM to spread, misregulate signaling pathways to facilitate their proliferation, promote angiogenesis to receive nutrients, and protect themselves against natural killer cells. This review focuses on the changes in the expression of HS biosynthetic and catabolic enzymes in several cancers, the resulting changes in HS fine structures, and the effects of these tumor specific HS signatures on promoting invasion, proliferation, and metastasis. It is possible to retard tumor progression by modulating the deregulated biosynthetic and catabolic pathways of HS chains through novel chemical biology approaches.

The tumor microenvironment: the making of a paradigm

What has been will be again, what has been done will be done again; there is nothing new under the sun

(Ecclesiastes 1:9)

Stephen Paget was the conceptual father of the role played by the Tumor Microenvironment (TME) in tumor progression. The focus of this essay is the developmental phase of the post Paget TME research. Attempts will be made to highlight some of the pioneering work of scientists from the late sixties through the eighties of last century who laid the foundations for the contemporary scientific achievements of TME research but whose ground breaking studies are rarely cited. This review should serve as a small tribute to their great work.

Decreased metastatic phenotype in cells resistant to aminolevulinic acid-photodynamic therapy

Photodynamic therapy (PDT) is a novel cancer treatment utilising a photosensitiser, visible light and oxygen. PDT often leaves a significant number of surviving tumour cells. In a previous work, we isolated and studied two PDT resistant clones derived from the mammary adenocarcinoma LM3 line (Int. J. Oncol. 29 (2006) 397-405). The isolated Clon 4 and Clon 8 exhibited a more fibroblastic, dendritic pattern and were larger than the parentals. In the present work we studied the metastatic potential of the two clones in comparison with LM3. We found that 100% of LM3 invaded Matrigel, whereas only 19+/-6% and 24+/-7% of Clon 4 and Clon 8 cells invaded. In addition, 100% of LM3 cells migrated towards a chemotactic stimulus whereas 38+/-8% and 73+/-10% of Clones 4 and 8, respectively, were able to migrate. In vivo, 100% of the LM3 injected mice developed spontaneous lung metastasis, whereas none of the Clon 8 did, and only one of the mice injected with Clon 4 did. No differences were found in the proteolytic enzyme profiles among the cells. Anchorage-dependent adhesion was also impaired in vivo in the resistant clones, evidenced by the lower tumour take, latency time and growth rates, although both clones showed in vitro higher binding to collagen I without overexpression of beta1 integrin. This is the first work where the metastatic potential of cells surviving to PDT has been studied. PDT strongly affects the invasive phenotype of these cells, probably related to a higher binding to collagen. These findings may be crucial for the outcome of ALA-PDT of metastatic tumours, although further studies are needed to extrapolate the results to the clinic employing another photosensitisers and cell types.

Inhibition of neovascularization by a cartilage factor

Neovascularization of developing, repairing or neoplastic tissues is regulated, at least partially, by a family of proteins of low molecular mass (1000 less than mol mass less than 50 000 Da) which can be extracted from avascular tissues, such as hyaline cartilage, aorta or bladder epithelium, by mild salt solutions. These extractable proteins, functionally defined as anti-invasion factor (AIF), act as local regulators for some of the major mechanistic pathways by which endothelial cells are thought to invade tissues during neovascularization, mainly by matrix-degrading enzymes and by increased rates of migration and proliferation. AIF contains a spectrum of proteinase (collagenase) inhibitory activities, as well as an endothelial cell growth inhibitor. The endothelial cell growth inhibitor is directed against actively dividing endothelial cells in culture but has no effect on endothelial cell monolayers or any other cell lines tested. In tumours, the AIF-derived endothelial cell growth inhibitor may limit tumour growth to less than 2 mm in diameter by inhibiting tumour neovascularization.

The enhanced expression of the matrix metalloproteinase 9 in nasal NK/T-cell lymphoma

Background

Nasal NK/T cell lymphoma is an aggressive disease and has a poor prognosis. Nasal NK/T cell lymphoma is refractory to conventional chemotherapy and has strong tendency of widespread relapse or dissemination into distant sites.

Methods

We immunohistochemically studied nasal NK/T-cell lymphoma to elucidate the unique characteristics of nasal NK/T-cell lymphoma, such as its higher metastatic tendency and its vast necrosis which leads to destruction of the involved tissues. The expression of P-glycoprotein and MMP-9 was evaluated in the 20 patients with nasal NK/T-cell lymphoma and 25 with nasal non-NK/T-cell lymphoma and the relationship between expression of these proteins and clinical results were analyzed in this report.

Results

Overall 5-year survival rates for patients with nasal NK/T cell lymphoma, and nasal non-NK/T cell lymphoma were 51%, and 84%. Distant involvement free 5-year survival rates for patients with nasal NK/T cell lymphoma, and nasal non-NK/T cell lymphoma were 53%, and 79%.

Overall positivity for P-glycoprotein was observed in 10 of 19 patients with NTL and in 13 of 23 patients with non-NTL. When the overall survival rate was compared between patients with P-glycoprotein positive and negative, there was no difference between them.

Sixteen of the 19 patients with nasal NK/T cell lymphoma expressed MMP-9. In contrast, only 8 of the 22 patients with nasal non-NK/T cell lymphoma expressed MMP-9. Distant involvement free 5-year survival rates for patients with MMP-9 negative, and MMP-9 positive were 92%, and 61%, respectively. The difference was statistically significant (p = 0.027).

Conclusion

Positive immunoreactivity for P-glycoprotein was not an independent prognostic factor in nasal NK/T-cell lymphomas, which stresses the importance of exploring other mechanisms of drug resistance. The strong expression of MMP-9 is uniquely characteristic of nasal NK/T cell lymphoma and may contribute to its strong tendency to disseminatate and the extensive necrosis which is always seen. However, our results are based on univariate comparisons, and as such, should be viewed with some caution.

Intravoxel distribution of DWI decay rates reveals C6 glioma invasion in rat brain

The hypothesis was tested that the intravoxel distribution of water diffusion rates, as measured with a stretched-exponential model of diffusion-weighted imaging (DWI), is a marker of brain tumor invasion. Eight rats underwent intracerebral inoculation of C6 glioma cells. In three rats, cells were labeled with a fluorescent dye for microscopy. One rat was inoculated with a saline solution, and five more rats were imaged without inoculation as controls. Five healthy uninoculated rats were also imaged. DWI was performed 14-15 days after inoculation, with diffusion-weighting factor b = 500 to 6500 sec/mm2, and the resulting signal attenuation was fitted with the stretched-exponential model. The heterogeneity index values were significantly lower (P < 0.05) in the peritumor ROI than in normal gray matter and significantly higher than in normal white matter. The distributed diffusion coefficient values were significantly lower than in normal white matter or normal gray matter. Fluorescence microscopy confirmed the presence of tumors in the peritumor region that could be histologically distinguished from the main tumor mass. There was no change in proton density or T2-weighted images in the peritumor region, making vasogenic edema unlikely as a source of contrast. It is therefore thought that the heterogeneity parameter alpha is a marker of brain tumor invasion.

Extra-cellular matrix in vascular networks

The vascular network is a series of linked conduits of blood vessels composed of the endothelium, a monolayer of cells that adorn the vessel lumen and surrounding layer(s) of mesenchymal cells (vascular smooth muscle, pericytes and fibroblasts). In addition to providing structural support, the mesenchymal cells are essential for vessel contractility. The extracellular matrix is a major constituent of blood vessels and provides a framework in which these various cell types are attached and embedded. The composition and organization of vascular extracellular matrix is primarily controlled by the mesenchymal cells, and is also responsible for the mechanical properties of the vessel wall, forming complex networks of structural proteins which are highly regulated. The extracellular matrix also plays a central role in cellular adhesion, differentiation and proliferation. This review examines the cellular and extracellular matrix components of vessels, with specific emphasis on the regulation of collagen type I and implications in vascular disease.

Increased Expression of Matrix Metalloproteinase 9 Correlates with Poor Prognostic Variables in Renal Cell Carcinoma

BACKGROUND

MMP2 and MMP9 are two gelatinolytic enzymes, which are key regulators of tumor invasion and metastasis. This study aimed to clarify the prognostic significance of MMP2 and MMP9 with particular regard to their transcript levels, enzymatic activities in renal cell carcinomas (RCCs).

MATERIALS AND METHODS

Through cDNA array, the differential expression of the MMP superfamily was evaluated in RCC. Various properties of MMP2 and MMP9 were quantified, in 178 patients with RCC, based on the Heidelberg classification. Of these, 145 cases including 16 fresh-frozen cases were available for MMP2 and MMP9 transcript level evaluation. In addition, gelatinolytic activity was assessed by zymography in 16 other fresh-frozen samples from new RCC cases.

RESULTS

MMP2, 9, 11, 14, and 16 were upregulated in the conventional RCC in comparison with the chromophobe RCC, whereas MMP1, 11 and 16 were pronounced in papillary RCC. MMP9 transcript levels were strongly associated with the MMP9 enzymatic activity (p=0.001), and therefore, with disease-free survival (p=0.001) and metastasis (p=0.011). Gelatinolytic activity of MMP9 by zymography was strongly associated with MMP9 mRNA expression, which was more intense in 'conventional' RCC than in 'chromophobe' RCC (p=0.001), irrespective of tumor grade or stage. MMP9 was proven to be a significant prognostic predictor by multi-variate survival analysis (p=0.0054). MMP2 enzymatic activity disappeared in spite of its constant transcript expression in RCC.

CONCLUSIONS

MMP9 appears to be regulated at the transcript level, whereas MMP2 is regulated at the posttranscriptional level. Poor survival with a high frequency of metastases in 'conventional' RCC is associated with MMP9, which exhibits a high transcriptional level, and a high gelatinolytic activity. As a result, MMP9 may be a candidate of predictors of disease-free survival in RCC.

Quantification of elastase-like activity in 13 human cancer cell lines and in an immortalized human epithelial cell line by RP-HPLC

A sensitive and specific RP-HPLC assay was developed to measure the levels of polymorphonuclear elastase (PMN-E) activity in growing cell cultures. By combining a pre-incubation of the cells with a relatively non-toxic, PMN-E-specific inhibitor, MeOSuc-Ala-Ala-Pro-Val-chloromethylketone (MAAPVCK), the p-nitroaniline formed by the hydrolysis of the substrate MeOSuc-Ala-Ala-Pro-Val-p-NA by PMN-E is quantified. Elastase-like activity was measured in 14 human cells lines: 13 cancer cell lines (HL-60, U-937, A-427, LCLC-103H, YAPC, DAN-G, PA-TU-8902, KYSE-70, -510, -520, 5637, SISO and MCF-7) and one immortalized epithelial cell line (hTert-RPE1). Activity was detected in all lines; the lowest was found in hTert-RPE1 cells while the highest was detected in a pancreas adenocarcinoma line (PA-TU-8902). When the results were normalized according to cell volume instead of cell number, the leukemia line HL-60 had the highest activity and PA-TU-8902 ranked second. A 1 h pre-incubation with 9.0 microM of the irreversible PMN-E inhibitor MAAPVCK led to varying degrees of enzyme inhibition depending on the cell line; the strongest inhibition was observed with the PA-TU-8902 pancreatic cancer cell line (90% inhibition) while the weakest was seen with the A-427 lung cancer cell line (52%). These results indicate that PA-TU-8902 is a suitable in vitro model for testing the efficacy of PMN-E-activated prodrugs of antitumor agents.

Downregulation of hemidesmosomal proteins in nasopharyngeal carcinoma cells

Hemidesmosome (HD) is a transmembrane complex that mediates attachment of epithelial cells to the basement membrane. Abnormal expression of HD components has been reported in several types of human cancers and is believed to play a role in tumor invasion and metastasis. Using differential gene display, we have identified downregulation of BPAG1 expression in nasopharyngeal carcinoma cells. BPAG1 is a major component of hemidesmosome. In the present study, we have extended our work to investigate the expression pattern of other components in the HD complex, namely, BPAG2, ITGalpha6 and ITGbeta4 in three distinct biological groups of nasopharyngeal epithelial cells: (a) non-malignant nasopharyngeal epithelial cells established from primary culture of nasopharyngeal explants, (b) non-malignant nasopharyngeal epithelial cells immortalized by viral oncogenes, SV40 or HPV16E6E7, and (c) nasopharyngeal carcinoma (NPC) cells. Both non-malignant primary cultured nasopharyngeal epithelial cells and immortalized nasopharyngeal epithelial cell lines expressed all the HD components examined, although the immortalized cells expressed a lower level of HD components compared with the non-malignant nasopharyngeal cells established from primary culture. In contrast, downregulation of HD components is commonly observed in nasopharyngeal carcinoma cells. Loss of HD expression in NPC may be associated with the undifferentiated properties of NPC cells and may have prognostic significance.

Matrix metalloproteinases in tumor invasion and metastasis

Extensive work on the mechanisms of tumor invasion and metastasis has identified matrix metalloproteinases (MMPs) as key players in the events that underlie tumor dissemination. Studies using natural and synthetic MMP inhibitors, as well as tumor cells transfected with cDNAs encoding the MMPs characterized thus far have provided compelling evidence that MMP activity can induce or enhance tumor survival, invasion and metastasis. Because of the ability of MMPs to degrade extracellular matrix (ECM) proteins, the principal mechanism whereby MMPs promote tumor development has been thought to be the proteolytic breakdown of tissue barriers to invasion and the associated facilitation of circulating tumor cell extravasation. However, recent evidence stemming from the use of novel experimental approaches indicates that MMPs do not play a major role in the process of extravasation itself. Rather, they appear to promote intravasation (the process of penetrating the circulation following invasion of blood vessels) and regulate the relationship between tumor cells and host tissue stroma subsequent to extravasation. In addition, the discoveries that a growing number of proteolytically active MMPs may localize to the cell surface in association with adhesion receptors, and that MMP substrates include latent cytokines and growth factors, provide a new conceptual framework for the mechanisms whereby MMPs influence tumor behavior.

Breast tumour cell-induced down-regulation of type I collagen mRNA in fibroblasts

This study investigated the modulation of type I collagen gene expression in normal fibroblasts by breast tumour cells. Northern analysis of total RNA extracted from stages I, II and III breast tumour tissue revealed that collagen mRNA levels were elevated in stage I tumours compared to the adjacent normal breast tissues, whereas they were decreased in stages II and III breast tumours. This aberrant collagen gene expression was confirmed by non-radioactive RNA:RNA in situ hybridization analysis of 30 breast carcinomas which localized the production of type I collagen mRNA to the stromal fibroblasts within the vicinity of the tumour cells. In order to determine whether the tumour cells were directly responsible for this altered collagen production by the adjacent fibroblasts, breast tumour cell lines were co-cultured with normal fibroblasts for in vitro assessment of collagen and steady-state collagen RNA levels. Co-culture of tumour cells and normal fibroblasts in the same dish resulted in down-regulation of collagen mRNA and protein. Treatment of the fibroblasts with tumour-cell conditioned medium also resulted in decreased collagen protein levels but the mRNA levels, however, remained unaltered. These results suggested that the tumour cells either secrete a labile 'factor', or express a cell surface protein requiring direct contact with the fibroblasts, resulting in down-regulation of collagen gene expression. Modulation of the ECM is a common characteristic of invading tumour cells and usually involves increased production of collagenases by the tumour cells or stromal fibroblasts. This study showed that tumour cells were also able to modulate collagen mRNA production by stromal fibroblasts, which may facilitate tumour cell invasion and metastasis.

Matrix metalloproteinase 9 expression is induced by Epstein-Barr virus latent membrane protein 1 C-terminal activation regions 1 and 2

Nasopharyngeal carcinoma (NPC), which is closely associated with the Epstein-Barr virus (EBV), is a highly metastatic malignant tumor. An important activity in tumor invasion and metastasis is that of the 92-kDa type IV collagenase or gelatinase, matrix metalloproteinase 9 (MMP-9), which mediates the degradation of the basement membrane and extracellular matrix. The expression of MMP-9 has been shown to be enhanced by the EBV oncoprotein, latent membrane protein 1 (LMP-1). LMP-1, which is expressed in NPC, has two essential signaling domains within the carboxy terminus, termed C-terminal activation regions 1 (CTAR-1) and CTAR-2. This study reveals that either signaling domain can activate the MMP-9 promoter and induce MMP-9 activity; however, LMP-1 deletion mutants lacking either CTAR-1 or CTAR-2 had a decreased ability to induce MMP-9 expression. The deletion of both activation regions completely abolished the induction of MMP-9 activity, while the cotransfection of both the CTAR-1 and CTAR-2 deletion mutants restored MMP-9 activity to levels produced by wild-type LMP-1. The NF-kappaB and activator protein 1 (AP-1) binding sites in the MMP-9 promoter were essential for the activation of MMP-9 gene expression by both CTAR-1 and CTAR-2. The induction of MMP-9 expression by LMP-1 and both CTAR-1 and CTAR-2 mutants was blocked by the overexpression of IkappaB. The tumor necrosis factor receptor-associated factor (TRAF) pathway also contributed to the activation of the MMP-9 promoter as shown by the use of TRAF-2 and TRAF-3 dominant-negative constructs. These data indicate that the activation of both the NF-kappaB and AP-1 pathways by LMP-1, CTAR-1, and CTAR-2 is necessary for the activation of MMP-9 expression. In NPC, LMP-1 may contribute to invasiveness and metastasis through the induction of MMP-9 transcription and enzymatic activity.

Metastatic carcinoma to skeletal muscle. A report of 15 patients

The records of 15 patients with metastatic carcinoma to skeletal muscle treated between 1979 and the present were reviewed. Fourteen patients were referred with a diagnosis of soft tissue sarcoma and one with suspected infection. There was a previous diagnosis of carcinoma in eight patients but seven patients had no prior diagnosis of a known malignancy. Primary tumors were lung (eight), melanoma (two), gastrointestinal (one), kidney (one), and bladder (one). No primary tumor could be identified in two patients. Local control of metastatic lesions was achieved by radiotherapy in 11 patients as an initial measure. Two patients underwent wide excision and one declined treatment for local tumor control. Eight patients died within 12 months of presentation and survival analysis indicated a 25% overall survival at 60 months. Two patients remained free of disease at 132 months and 72 months. From this study and a review of 52 cases reported in the literature, the authors are unable to find any clinical or radiographic characteristics that distinguish metastatic carcinoma to muscle from soft tissue sarcomas. Surgical resection can be reserved for cases in which radiation does not provide local control.

Association between the rat homologue of CO-029, a metastasis-associated tetraspanin molecule and consumption coagulopathy

Recently, we have described a panel of metastasis-associated antigens in the rat, i.e., of molecules expressed on metastasizing, but not on nonmetastasizing tumor lines. One of these molecules, recognized by the monoclonal antibody D6.1 and named accordingly D6. 1A, was found to be abundantly expressed predominantly on mesenchyme-derived cells. The DNA of the antigen has been isolated and cloned. Surprisingly, the gene product proved to interfere strongly with coagulation. The 1.182-kb cDNA codes for a 235-amino acid long molecule with a 74.2% homology in the nucleotide and a 70% homology in the amino acid sequence to CO-029, a human tumor-associated molecule. According to the distribution of hydrophobic and hydrophilic amino acids, D6.1A belongs to the tetraspanin superfamily. Western blotting of D6.1A-positive metastasizing tumor lines revealed that the D6.1A, like many tetraspanin molecules, is linked to further membrane molecules, one of which could be identified as alpha6beta1 integrin. Transfection of a low-metastasizing tumor cell line with D6.1A cDNA resulted in increased metastatic potential and provided a clue as to the functional role of D6.1A. We noted massive bleeding around the metastases and, possibly as a consequence, local infarctions predominantly in the mesenteric region and all signs of a consumption coagulopathy. By application of the D6.1 antibody the coagulopathy was counterregulated, though not prevented. It has been known for many years that tumor growth and progression is frequently accompanied by thrombotic disorders. Our data suggest that the phenomenon could well be associated with the expression of tetraspanin molecules.

What destroys the joint in rheumatoid arthritis?

The immunological disturbance in rheumatoid arthritis (RA) gives rise to a nonspecific inflammatory reaction mediated by cells and cytokines. This immunological nonbacterial synovitis, however, does not destroy the articular cartilage. The destruction of joint structures is the effect of tumor-like aggressive synoviogenic cell elements (TLP). These TLP formations are not observed in any other type of arthritis. TLP formations are strictly avascular and short-lived. After they have decayed, a collagenous pannus remains. Invasion and destruction of joint structures are brought about by several types of proteases, synthesized and secreted by highly active TLP cells. The TLP formations possess more than twice the affinity for adjacent bone than for the articular cartilage. In these formations, four oncogenes could be identified. In the course of RA disease, TLP formations can recur. Thus, the joint damage can summate with time. The oncological character of the aggressive process in RA demands new therapeutical considerations to protect RA patients from destruction of their joints.

Melanoma and stroma: an interaction of biological and prognostic importance

Stromal relationships are crucial to metastatic spread of solid malignancies. Some aspects of this stroma interaction are obviously associated with particular morphological features, which may carry prognostic significance. In cutaneous melanoma, level of invasion, arrangement of cells (horizontal or vertical growth phase), neovascularization, vessel invasion, architecture of the border, and inflammatory infiltrate have been examined. Expression of adhesion molecules, signalling factors, cytoskeletal components, extracellular matrix molecules and matrix-degrading enzymes have been assessed by immunohistology and in situ hybridization. Besides providing prognostic information, a thorough evaluation of stromal relationships may help to increase our knowledge about factors mediating the growth and metastatic spread of malignancies.

Hyaluronan: RHAMM mediated cell locomotion and signaling in tumorigenesis

Extracellular matrix molecules and their receptors are important regulators of cell movement, adhesion and cytoskeletal organization. Adhesion molecules can also serve to mediate signal transduction and can influence, and sometimes direct, the events required for tumorigenesis. The extracellular matrix molecule, hyaluronan and its receptors have been implicated in transformation and metastasis, in particular the processes of tumor cell motility and invasion. RHAMM (receptor for hyaluronan mediated motility) is required for the cell locomotion of ras-transformed fibrosarcoma cells, cytokine stimulated fibrobasts and T lymphocytes, malignant B cells, and breast carcinoma cells. HA:RHAMM interactions promote cell locomotion via a protein tyrosine kinase signal transduction pathway that targets focal adhesions. The tyrosine kinase pp60c-src is associated with RHAMM in cells and is required for RHAMM mediated cell motility. It is possible that a RHAMM/src pathway induces focal adhesions to signal the cytoskeletal changes required for elevated cell motility seen in tumor progression, invasion and metastasis.

Biology of human colon cancer metastasis

The process of metastasis is highly selective and favors the survival and growth of a few subpopulations of cells that preexist within a heterogeneous primary neoplasm. To produce metastases, tumor cells must succeed in invasion, embolization, survival in the circulation, arrest in a distant capillary bed, and extravasation into and multiplication in organ parenchyma. The outcome of this process depends on the interaction of metastatic cells with multiple host factors. To assess metastatic potential accurately, it is necessary to orthotopically implant human tumor cells recovered from surgical specimens into nude mice. This orthotopic implantation of tumor cells is invariably associated with trauma to the specific organ of implantation, which is followed by the processes of inflammation and repair. Tissue-specific growth factors may be responsible for stimulation of tumor cells that possess specific surface receptors. Understanding the factors that regulate cancer metastasis should allow for the design of rational therapy.

Hyaluronan and the hyaluronan receptor RHAMM promote focal adhesion turnover and transient tyrosine kinase activity

The molecular mechanisms whereby hyaluronan (HA) stimulates cell motility was investigated in a C-H-ras transformed 10T 1/2 fibroblast cell line (C3). A significant (p < 0.001) stimulation of C3 cell motility with HA (10 ng/ml) was accompanied by an increase in protein tyrosine phosphorylation as detected by anti-phosphotyrosine antibodies using immunoblot analysis and immunofluorescence staining of cells. Tyrosine phosphorylation of several proteins was found to be both rapid and transient with phosphorylation occurring within 1 min of HA addition and dissipating below control levels 10-15 min later. These responses were also elicited by an antibody generated against a peptide sequence within the HA receptor RHAMM. Treatment of cells with tyrosine kinase inhibitors (genistein, 10 micrograms/ml or herbimycin A, 0.5 micrograms/ml) or microinjection of anti-phosphotyrosine antibodies inhibited the transient protein tyrosine phosphorylation in response to HA as well as prevented HA stimulation of cell motility. To determine a link between HA-stimulated tyrosine phosphorylation and the resulting cell locomotion, cytoskeletal reorganization was examined in C3 cells plated on fibronectin and treated with HA or anti-RHAMM antibody. These agents caused a rapid assembly and disassembly of focal adhesions as revealed by immunofluorescent localization of vinculin. The time course with which HA and antibody induced focal adhesion turnover exactly paralleled the induction of transient protein tyrosine phosphorylation. In addition, phosphotyrosine staining colocalized with vinculin within structures in the lamellapodia of these cells. Notably, the focal adhesion kinase, pp125FAK, was rapidly phosphorylated and dephosphorylated after HA stimulation. These results suggest that HA stimulates locomotion via a rapid and transient protein tyrosine kinase signaling event mediated by RHAMM. They also provide a possible molecular basis for focal adhesion turnover, a process that is critical for cell locomotion.

Distribution of basal lamina type IV collagen and laminin in normal rat tongue mucosa and experimental oral carcinoma: ultrastructural immunolocalization and immunogold quantitation

The relationship of basal lamina, a form of specialised extracellular matrix which separates epithelial cells and other cell types from adjacent stroma, to the behaviour of malignant neoplasms of epithelial origin is not well understood. However, it is widely acknowledged that the properties of local invasion and metastasis of carcinomas are linked to extracellular matrix (including basal lamina) changes. In the present study, the distribution of the major basal lamina components, type IV collagen and laminin, in normal rat tongue mucosa and experimentally induced oral carcinomas was investigated using post-embedding immunogold techniques and electron microscopy. The expression of these components was also quantitatively analysed using morphometry and immunocytochemistry. Results indicated that type IV collagen and laminin were confined to the lamina densa of normal oral epithelial basal lamina, and that both components were also detected in the lamina densa of basal lamina associated with carcinomas, and in the extracellular matrix of tumours. Furthermore, laminin was detected within stromal fibroblasts in normal tissues and experimental carcinomas. Quantitative analysis indicated that expression of laminin was significantly increased in carcinomas. In contrast, type IV collagen expression was significantly decreased. The quantitative changes observed in the two basal lamina constituents may be related to the process of tumour invasion, reflecting altered metabolic activities of tumour and stromal cells. These observations may be of use in understanding the architectural characteristics of oral mucosa basal lamina and in assessing the malignant potential of epithelial dysplasias or "premalignant" lesions.