Cell-contact and -architecture of malignant cells and their relationship to metastasis

ALCAM contributes to brain metastasis formation in non-small-cell lung cancer through interaction with the vascular endothelium

Background

Brain metastasis (BM) in non-small-cell lung cancer (NSCLC) has a very poor prognosis. Recent studies have demonstrated the importance of cell adhesion molecules in tumor metastasis. The aim of our study was to investigate the role of activated leukocyte cell adhesion molecule (ALCAM) in BM formation in NSCLC.

Methods

Immunohistochemical analysis was performed on 143 NSCLC primary tumors and BM. A correlation between clinicopathological parameters and survival was developed. Biological properties of ALCAM were assessed in vitro by gene ablation using CRISPR/Cas9 technology in the NCI-H460 NSCLC cell line and in vivo by intracranial and intracardial cell injection of NCI-H460 cells in NMRI-Foxn1^nu/nu mice.

Results

ALCAM expression was significantly upregulated in NSCLC brain metastasis (P = 0.023) with a de novo expression of ALCAM in 31.2% of BM. Moderate/strong ALCAM expression in both primary NSCLC and brain metastasis was associated with shortened survival. Functional analysis of an ALCAM knock-out (KO) cell line showed a significantly decreased cell adhesion capacity to human brain endothelial cells by 38% (P = 0.045). In vivo studies showed significantly lower tumor cell dissemination in mice injected with ALCAM-KO cells in both mouse models, and both the number and size of BM were significantly diminished in ALCAM depleted tumors.

Conclusions

Our findings suggest that elevated levels of ALCAM expression promote BM formation in NSCLC through increased tumor cell dissemination and interaction with the brain endothelial cells. Therefore, ALCAM could be targeted to reduce the occurrence of BM.

Key Points

1. ALCAM expression associates with poor prognosis and brain metastasis in NSCLC.

2. ALCAM mediates interaction of NSCLC tumor cells with brain vascular endothelium.

3. ALCAM might represent a novel preventive target to reduce the occurrence of BM in NSCLC.

The mechanisms of IL-17A on promoting tumor metastasis

In recent decades, extensive studies have indicated that IL-17A plays an important role in tumor progression and metastasis, but the underlying mechanisms are not immediately clear. In this review, we examined the literature from the recent years concerning the study of IL-17A in four kinds of tumor transfer paths, including hematogenous metastasis, lymphatic metastasis, local invasion and transcoelomic metastasis, to summarize the roles and underlying mechanisms of IL-17A on tumor metastasis.

Interleukin 17A promotes hepatocellular carcinoma metastasis via NF-kB induced matrix metalloproteinases 2 and 9 expression

BACKGROUND

 IL-17A is a pro-inflammatory cytokine that plays important role in inflammatory disease pathology and tumor microenvironment. The aim of this study is to investigate the effect of IL-17A on the progression of hepatocellular carcinoma (HCC).

METHODOLOGY AND PRINCIPAL FINDING

Expression pattern of IL-17A in clinical HCC samples (n = 43) was determined by immunohistochemistry staining. Transcript levels of MMP2, MMP9 and IL-17A were measured in another 50 pairs (including tumor and related non-tumor tissues) HCC samples. Cell growth, focus formation, cell migration, invasion and western blot assays were used to characterize the functional and signaling mechanisms in IL-17A-treated HCC. Association study was used to identify clinical significance of IL-17A in HCC. Compared with paired non-tumor tissue, higher frequency of IL-17A-positive cells was detected in tumor tissues in HCCs with metastasis, and the frequency of IL-17A-positive cells was also significantly associated with poor prognosis of HCC (P = 0.01). Functional study found that IL-17A could promote HCC cell migration and invasion. Further molecular analysis also showed that IL-17A could upregulate MMP2 and MMP9 expression via NF-κB signaling activation.

CONCLUSIONS

 IL-17A could promote HCC metastasis by the upregulation of MMP2 and MMP9 expression via activating NF-κB signaling pathway.

Adhesion mechanisms in embryogenesis and in cancer invasion and metastasis

Cell-substratum and cell-cell adhesion mechanisms contribute to the development of animal form. The adhesive status of embryonic cells has been analysed during epithelial-mesenchymal cell interconversion and in cell migrations. Clear-cut examples of the modulation of cell adhesion molecules (CAMs) have been described at critical periods of morphogenesis. In chick embryos the three primary CAMs (N-CAM. L-CAM and N-cadherin) present early in embryogenesis are expressed later in a defined pattern during morphogenesis and histogenesis. The axial mesoderm derived from gastrulating cells expresses increasing amounts of N-cadherin and N-CAM. During metamerization these two adhesion molecules become abundant at somitic cell surfaces. Both CAMs are functional in an in vitro aggregation assay; however, the calcium-dependent adhesion molecule N-cadherin is more sensitive to perturbation by specific antibodies. Neural crest cells which separate from the neural epithelium lose their primary CAMs in a defined time-sequence. Adhesion to fibronectins via specific surface receptors becomes a predominant interaction during the migratory process, while some primary and secondary CAMs are expressed de novo during the ontogeny of the peripheral nervous system. In vitro, different fibronectin functional domains have been identified in the attachment, spreading and migration of neural crest cells. The fibronectin receptors which transduce the adhesive signals play a key role in the control of cell movement. All these results have prompted us to examine whether similar mechanisms operate in carcinoma cell invasion and metastasis. In vitro, rat bladder transitional carcinoma cells convert reversibly into invasive mesenchymal cells. A rapid modulation of adhesive properties is found during the epithelial-mesenchymal carcinoma cell interconversion. The different model systems analysed demonstrate that a limited repertoire of adhesion molecules, expressed in a well-defined spatiotemporal pattern, is involved in tissue formation and in key processes of tumour spread.

Adhesive properties of metastasizing tumour cells

Cancer metastasis depends on a functional property which enables tumour cells to depart from the primary site of growth, to disseminate to distant organs and to establish secondary growth. The acquisition of a metastatic phenotype by neoplastic cells most probably involves alterations in their adhesive properties as the migrating cells continuously break and establish cellular contacts throughout the process. In vitro, normal cells of either mesenchymal or epithelial origin usually depend on adhesion to and spreading on a solid substratum (anchoring) for cell division. Neoplastic cells, however, are free of dependence on the support of solid substrata for cell proliferation (anchorage independent). The search for the characteristic alterations in cell adhesion, spreading and morphology which may accompany neoplastic transformation in general and cancer metastasis in particular has engendered a wide range of research activities. These studies have led to the identification of various membrane receptors that mediate cell-cell and cell-extracellular matrix recognition and adhesion on normal and tumour cells. Central to this is the effect of cell adhesion on cell shape and cytoskeleton organization in relation to metastasis. The use of specific antibodies, ligands, drugs and culture conditions permits exploration and identification of some of the macromolecules involved in tumour cell adhesion in vitro and metastasis in vivo. Nevertheless the specificity of the interactions which might determine organ-specific metastasis remains to be elucidated. This paper discusses the interrelation between cell adhesion, cell shape, cytoskeleton and metastasis.

Large-scale optimization-based classification models in medicine and biology

We present novel optimization-based classification models that are general purpose and suitable for developing predictive rules for large heterogeneous biological and medical data sets. Our predictive model simultaneously incorporates (1) the ability to classify any number of distinct groups; (2) the ability to incorporate heterogeneous types of attributes as input; (3) a high-dimensional data transformation that eliminates noise and errors in biological data; (4) the ability to incorporate constraints to limit the rate of misclassification, and a reserved-judgment region that provides a safeguard against over-training (which tends to lead to high misclassification rates from the resulting predictive rule); and (5) successive multi-stage classification capability to handle data points placed in the reserved-judgment region. To illustrate the power and flexibility of the classification model and solution engine, and its multi-group prediction capability, application of the predictive model to a broad class of biological and medical problems is described. Applications include: the differential diagnosis of the type of erythemato-squamous diseases; predicting presence/absence of heart disease; genomic analysis and prediction of aberrant CpG island meythlation in human cancer; discriminant analysis of motility and morphology data in human lung carcinoma; prediction of ultrasonic cell disruption for drug delivery; identification of tumor shape and volume in treatment of sarcoma; discriminant analysis of biomarkers for prediction of early atherosclerois; fingerprinting of native and angiogenic microvascular networks for early diagnosis of diabetes, aging, macular degeneracy and tumor metastasis; prediction of protein localization sites; and pattern recognition of satellite images in classification of soil types. In all these applications, the predictive model yields correct classification rates ranging from 80 to 100%. This provides motivation for pursuing its use as a medical diagnostic, monitoring and decision-making tool.

Cellular chemomechanics at interfaces: sensing, integration and response

Living cells are complex entities whose remarkable, emergent capacity to sense, integrate, and respond to environmental cues relies on an intricate series of interactions among the cell's macromolecular components. Defects in mechanosensing, transduction,or responses underlie many diseases such as cancers, immune disorders, cardiac hypertrophy, genetic malformations, and neuropathies. Here, we highlight micro- and nanotechnology-based tools that have been used to study how chemical and mechanical cues modulate the responses of single cells in contact with the extracellular environment. Understanding the physical aspects of these complex processes at the micro- and nanometer scale could produce profound and fundamental new insights into how the processes of cell migration, metastasis, immune function and other areas which are regulated by mechanical forces.

Prognostic significance of MCM2, Ki-67 and gelsolin in non-small cell lung cancer

Background

Uncontrolled proliferation and increased motility are hallmarks of neoplastic cells, therefore markers of proliferation and motility may be valuable in assessing tumor progression and prognosis. MCM2 is a member of the minichromosome maintenance (MCM) protein family. It plays critical roles in the initiation of DNA replication and in replication fork movement, and is intimately related to cell proliferation. Ki-67 is a proliferation antigen that is expressed during all but G₀ phases of the cell cycle. Gelsolin is an actin-binding protein that regulates the integrity of the actin cytoskeletal structure and facilitates cell motility. In this study, we assessed the prognostic significance of MCM2 and Ki-67, two markers of proliferation, and gelsolin, a marker of motility, in non-small cell lung cancer (NSCLC).

Methods

128 patients with pathologically confirmed, resectable NSCLC (stage I-IIIA) were included. Immunohistochemistry was utilized to measure the expressions of these markers in formalin-fixed, paraffin-embedded tumor tissues. Staining and scoring of MCM2, Ki-67 and gelsolin was independently performed. Analyses were performed to evaluate the prognostic significance of single expression of each marker, as well as the prognostic significance of composite expressions of MCM2 and gelsolin. Cox regression and Kaplan-Meier survival analysis were used for statistical analysis.

Results

Of the three markers, higher levels of gelsolin were significantly associated with an increased risk of death (adjusted RR = 1.89, 95% CI = 1.17–3.05, p = 0.01), and higher levels of MCM2 were associated with a non-significant increased risk of death (adjusted RR = 1.36, 95% CI = 0.84–2.20, p = 0.22). Combined, adjusted analyses revealed a significantly poor prognostic effect for higher expression of MCM2 and gelsolin compared to low expression of both biomarkers (RR = 2.32, 95% CI = 1.21–4.45, p = 0.01). Ki-67 did not display apparent prognostic effect in this study sample.

Conclusion

The results suggest that higher tumor proliferation and motility may be important in the prognosis of NSCLC, and composite application of biomarkers might be of greater value than single marker application in assessing tumor prognosis.

Prognostic significance of gelsolin expression level and variability in non-small cell lung cancer

BACKGROUND

Gelsolin is an actin-binding protein that mediates cellular motility and maintains the integrity of cytoskeletal structure. Diminished expression of gelsolin has been observed in human cancer cell lines and tumors. Studies of the prognostic effect of gelsolin expression (GE) in non-small cell lung cancer (NSCLC) are rare and results are inconsistent to date. The present study used immunohistochemistry to evaluate the prognostic effect of gelsolin expression in 155 patients with resectable NSCLC.

METHODS

Detection of gelsolin in tumor cells was performed by immunohistochemistry, and two approaches to classification were used to describe expression: expression level (negative, reduced or high) and expression uniformity (uniform or variable). Expression level was determined by a weighted index of intensity of staining (i.e., overall tendency) in the specimen. Expression uniformity was based on the presence or absence of variability in immunostaining within the tumor section. Chi-square test, student t-test, Cox proportional hazards regression and Kaplan-Meier survival analysis were used in data analyses.

RESULTS

After controlling for covariates, high level gelsolin expression was significantly associated with poor survival compared with negative gelsolin expression in NSCLC, and this adverse prognostic effect was specific to patients with stage II tumors and for patients with squamous cell carcinomas. Similarly, variable gelsolin expression was significantly associated with poor survival compared with uniform gelsolin expression and this adverse prognostic effect was also specific to patients with stage II tumors and for patients with squamous cell carcinomas.

CONCLUSION

High level gelsolin expression and variable gelsolin expression are adverse prognostic factors for NSCLC in this study, which might manifest the high motility and heterogeneity of tumor cells, two distinguishing characteristics for tumors with potentially enhanced invasive and dissemination capabilities.

Hepatocyte growth factor/scatter factor is implicated in the mode of stromal invasion of uterine squamous cervical cancer

OBJECTIVE

The purpose of this study was to examine the relationship of hepatocyte growth factor/scatter factor (HGF/SF) to cell motility and invasion in uterine cervical cancer.

METHODS

We examined the expression of HGF/SF and its receptor, c-met, in cervical cancer cell lines SKG-IIIa (squamous cell carcinoma) and Hela-S3 (adenocarcinoma) and in stromal cells of the cervical cancer tissue by reverse transcription-polymerase chain reaction. We studied the effect of HGF/SF on invasiveness of SKG-IIIa and Hela-S3 in an invasion model of the modified Boyden chamber method and by electron microscopy. SKG-IIIa cells were also seeded on the thick Matrigel-coated layer to evaluate the invasion patterns in three-dimensional directions. To investigate the mechanism of an inductive effect of HGF/SF on the invasiveness of SKG-IIIa, we examined the effect of HGF/SF on the expression of intercellular adhesion molecule E-cadherin, cell-substrate adhesion molecules CD44, alpha2beta1, and alpha6beta1, and intracellular skeleton fiber actin in SKG-IIIa in cell enzyme-linked immunosorbent assay (ELISA) and immunofluorescence staining.

RESULTS

HGF/SF messenger RNA (mRNA) was detected in stromal cells, and c-met mRNA was detected in SKG-IIIa and Hela-S3. Hela-S3 that initially showed weak intercellular contact freely invaded the Matrigel-coated multiporous membrane without the addition of HGF/SF. In contrast, SKG-IIIa that initially showed strong intercellular adhesion could invade the membrane after the addition of HGF/SF. The same results were represented by an addition of HECD-1, an anti-human E-cadherin antibody. In an experiment with cell culture in a thick Matrigel layer, control SKG-IIIa showed a mirror-ball-like invasion pattern, whereas HGF/SF-stimulated SKG-IIIa spread horizontally over the membrane and migrated through the membrane holes, presenting a tentacular invasion pattern. Migration of SKG-IIIa under the membrane was confirmed by scanning and transmission electron microscopy. The addition of HGF/SF in cell ELISA assay decreased the expression of E-cadherin and actin in SKG-IIIa, but it did not change the expression of CD44, alpha2beta1, and alpha6beta1. Immunofluorescence staining revealed that the expression of E-cadherin in cell membrane was disturbed by HGF/SF.

CONCLUSIONS

Our data indicate that HGF/SF produced by stromal cells influences the mode of stromal invasion of squamous cervical cancer by selectively decreasing the expression of both E-cadherin and actin.

Suppression of C8161 melanoma metastatic ability by chromosome 6 induces differentiation-associated tyrosinase and decreases proliferation on adhesion-restrictive substrates mediated by overexpression of p21WAF1 and down-regulation of bcl-2 and cyclin D3

Metastatic tumors grow under conditions that restrict proliferation of non-metastatic, more differentiated cells. To investigate this prediction, we developed a simple adhesion-restrictive assay which allows proliferation of human metastatic C8161 melanoma, but prevents growth of neo 6.3/C8161 cells in which metastasis is suppressed by introduction of neo-tagged chromosome 6. We show that tyrosinase, a key enzyme in melanocytic cell differentiation, and expression of chromosome 6-encoded cell cycle modulators like p21WAF1 and cyclin D3 is selectively increased in C8161 tumors in which metastasisis is suppressed by chromosome 6. In the latter cells, growth arrest evidenced only under adhesion-restrictive conditions correlated with down-regulation of cyclin D3 and anti-apoptotic bcl-2. No comparable growth arrest or down-regulation was detected under comparable conditions in metastatic cells, which showed activation of invasion-associated MMP-9 92 kDa gelatinase B. Our data suggests that the metastasis-suppressing effects of chromosome 6 involving increased differentiation-associated tyrosinase and growth arrest on adhesion-restrictive substrates; are partly mediated by modulation of growth regulators, like p21WAF1 and cyclin D3.

A novel model for invasion of cancer cells using the submucosal layer of the human stomach

An in vitro model for studying the invasion mechanism of cancer cells was established using the submucosal layer of the human stomach. Submucosa prepared from a surgical specimen was maintained in an organ culture. The cytoarchitecture of the cultured submucosa remained well preserved; viability remained for over 2 weeks. When human gastric cancer cell lines MKN45, MKN74, and Kato III were seeded onto the submucosal slices, cancer cells of MKN45 and KATO III invaded the submucosa 3 days after inoculation. However, MKN74 cells were not seen in the submucosal slices. Our invasion model, which mimics the in vivo conditions of the submucosa of human stomach, may make it possible to analyze actual events of human gastrointestinal malignant cell invasion in normal submucosa in vitro. The usefulness of our invasion model lies in the choice of the submucosal layer of the human stomach as the host tissue. The histarchitecture of the submucosal slices indicates that the model has potential for studies of the mechanism of interactions between carcinoma cells and host tissue similar to interactions that may occur in vivo. Moreover, this method allows the continuous microscopic observation of cells within the living submucosa. Using this model, a novel approach to controlling the local invasion of tumor cells may lead to a promising, radical cure for these intractable neoplasms. Our model system is an in vitro model that is facile, inexpensive, and experimentally manipulative.

The dual role of cytoskeletal anchor proteins in cell adhesion and signal transduction

beta-Catenin and plakoglobin are homologous proteins having a dual role in cell adhesion and in transactivation together with LEF/TCF transcription factors. Overexpression of plakoglobin suppresses tumorigenicity, whereas increased beta-catenin levels are considered oncogenic. We compared the nuclear translocation and transactivation by beta-catenin and plakoglobin. Overexpression of each protein resulted in nuclear translocation and formation of structures that also contained LEF-1 and vinculin with beta-catenin, but not with plakoglobin. Transfection of LEF-1 translocated endogenous beta-catenin, but not plakoglobin into the nucleus. Chimeras of the Gal4 DNA-binding domain and the transactivation domains of either plakoglobin or beta-catenin were equally potent in transactivation, but induction of LEF-1-responsive transcription was higher with beta-catenin. Overexpression of wt plakoglobin or mutant beta-catenin lacking the transactivation domain induced nuclear accumulation of the endogenous beta-catenin and LEF-1-responsive transactivation. The nuclear localization and constitutive beta-catenin-dependent transactivation in SW480 cancer cells were inhibited by overexpressing cadherin or alpha-catenin. Moreover, transfecting the cytoplasmic tail of cadherin inhibited transactivation, by competition with LEF-1 in the nucleus for beta-catenin binding. The results indicate that (1) plakoglobin and beta-catenin differ in nuclear translocation and complexing with LEF-1 and vinculin, (2) LEF-1-dependent transactivation is mainly driven by beta-catenin, (3) cadherin and alpha-catenin can sequester beta-catenin, inhibit its transcriptional activity, and antagonize its oncogenic action.

Induction of autocrine factor inhibiting cell motility from murine B16-BL6 melanoma cells by alpha-melanocyte stimulating hormone

We have previously reported that neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH) successfully inhibited Matrigel invasion and haptotactic migration of B16-BL6 melanoma cells towards both fibronectin and laminin without affecting their growth. In the present study, we investigated the inhibitory mechanism of tumor cell motility by alpha-MSH. Alpha-MSH significantly blocked the autocrine motility factor (AMF)-enhanced cell motility. However, alpha-MSH did neither prevent the secretion of AMF from B16-BL6 cells nor alter the expression level of AMF receptor (gp78). On the other hand, alpha-MSH induced the secretion of the motility inhibitory factor(s) from B16-BL6 cells in a concentration- and time-dependent manner. The induction of the motility inhibitor(s) was proportional to increasing levels of intracellular cAMP induced by alpha-MSH as well as forskolin, and the activity was abolished by an adenylate cyclase inhibitor, 2',5'-dideoxyadenosine (DDA). The motility-inhibiting activity in conditioned medium (CM) from alpha-MSH-treated B16-BL6 cells was found to have a m.w. below 3 kDa after fractionation. This activity was abolished by boiling but insensitive to trypsin. The treatment of tumor cells with cycloheximide reduced the activity in alpha-MSH-stimulated CM. Our results suggest that alpha-MSH inhibited the motility of B16-BL6 cells through induction of autocrine factor(s).

Development and validation of a sensitive solid-phase extraction and high-performance liquid chromatography assay for the novel antitumour agent CT2584 in human plasma

A HPLC assay and solid-phase extraction technique from human plasma has been developed and validated for the novel anticancer agent CT2584, 1-(11-dodecylamino-10-hydroxyundecyl)-3,7-dimethylxanthine, which has recently completed a phase I trial at the Christie Hospital, Manchester under the auspices of the CRC phase I/II committee. Following addition of CT2576, 1-(11-octylamino-10-hydroxylundecyl)-3,7-dimethylxanthine, as internal standard, a solid-phase extraction cartridge (100 mg cyanopropyl) was used to isolate the drug CT2584 from human plasma. Analysis was performed by reversed-phase chromatography. CT2576 was used as internal standard at a concentration of 4 microg ml(-1) for the quantification of CT2584 from plasma for the duration of this work. The lower limit of quantification for the drug CT2584 in buffer using this assay was found to be 0.0122 microM (0.008 microg ml(-1)) and 0.048 microM (0.027 microg ml(-1)) when extracted from human plasma.

The role of cellular motility in the invasion of human neuroblastoma cells with or without N-myc amplification and expression

BACKGROUND/PURPOSE

Patients who have neuroblastomas with N-myc amplification that are extremely invasive and result in distant metastases tend to have a very poor prognosis. The authors reported previously that N-mycamplification and expression might be closely related to the invasiveness of human neuroblastoma cells. However, the role of cellular motility has not yet been clarified in the invasion of neuroblastoma cells. The aim of this study was, therefore, to elucidate the role of cellular motility in the invasion of neuroblastoma cells.

METHODS

Six human neuroblastoma cell lines were used for an invasion assay in vitro using polycarbonate filters coated with basement membrane Matrigel. The amplification and expression of N-myc oncogene was examined by Southern and Northern blotting, respectively. The cellular motility was quantified by computerized image analysis on the morphology of cultured cells.

RESULTS

IMR-32, GOTO, and DZ, all of which had N-myc amplification, showed a high degree of invasiveness and a high cellular motility, whereas NB-69 and SK-N-SH without N-myc amplification showed an extremely low degree of invasiveness and cellular motility. ST without N-myc amplification, which was established from an aggressive tumor, showed an exceptionally high degree of motility and invasiveness. A transcriptional reduction of the N-myc gene by retinoic acid (RA) decreased the motility, which thus resulted in a marked decline of invasiveness in IMR-32 and GOTO.

CONCLUSION

The cellular motility correlated with the invasive capacity of human neuroblastoma cells, which thus indicated that cellular motility may play an important role in invasion.

Differences in the migration capacity of primary human colon carcinoma cells (SW480) and their lymph node metastatic derivatives (SW620)

Two human cell lines, one established from a colon carcinoma (SW480) and the other from its lymph node metastasis (SW620), were compared with respect to their migration capacity employing a three-dimensional collagen matrix and time-lapse video recording. Non-motile cells were characterized by a round shape, whereas motile cells appeared in an elongated form with pseudopodia. The primary tumor cells showed a higher spontaneous locomoting activity than the cells from the metastasis. Using single cell analysis, the distance migrated within 15 h was slightly increased in the presence of hyaluronic acid (HA) in both cell lines. An investigation of the amount of CD44 on the cell surface using the anti-CD44 antibody Hermes-1 showed only minor concentrations of this glycoprotein on cells from the metastasis, whereas a much higher amount was found on cells derived from the primary tumor. The distribution of CD44 on the cell surfaces of HA-treated and untreated cells did not differ as shown by confocal laser scanning microscopy in SW480. The results indicate a restricted influence of HA on migration in the two cell lines.

Influence of hyaluronic acid or phorbol 12-myristate 13-acetate on the migration capacity of a murine lymphoma cell line (Eb) and its metastatic variant (ESb)

The in vitro migration of two murine T cell lymphoma cell lines (Eb and ESb) was studied employing a three-dimensional collagen matrix and time-lapse video recording. In the highly metastatic cell line ESb, which had a low spontaneous locomoting activity, migration could clearly be stimulated by hyaluronic acid (HA) whereas only a small increase was found after incubation with phorbol myristate acetate (PMA). The observed stimulation could be attributed to an increase in recruitment of locomoting cells and not to changes in migration parameters of motile individual cells such as percentage of time locomoting, velocity or distance migrated. Incubation of the low metastatic cell line Eb with HA led to a decrease in migration but blocking of CD44, the principle ligand for HA, by preincubation with an anti-CD44 mAb (KM114), followed by HA exposure increased the locomoting activity significantly. The effect was based on both an increase in recruitment as well as in all migration parameters regarding motile individual Eb cells.

Basic fibroblast growth factor regulates proliferation and motility of human hepatoma cells by an autocrine mechanism

BACKGROUND/AIMS

Basic fibroblast growth factor has mitogenic and angiogenic properties. In this study, we aimed to evaluate the role of fibroblast growth factor in the development and progression of human hepatocellular carcinoma.

METHODS

The expression of basic fibroblast growth factor, fibroblast growth factor receptor-1, and a receptor isoform was investigated by in situ hybridization, immunohistochemistry, reverse transcription-polymerase chain reaction, Western blot analysis and confocal laser-scanning microscopy. The influence of exogenous basic fibroblast growth factor on DNA synthesis and motility of human hepatoma cells were also evaluated.

RESULTS

Basic fibroblast growth factor and fibroblast growth factor receptor-1 messenger RNAs were present mainly in tumor cells and less so in hepatocytes from noncancerous liver tissue. Immunoreactive products of basic fibroblast growth factor and fibroblast growth factor receptor-1 were observed in tumor cells. The isoform IIIc was expressed in hepatocellular carcinoma tissue and hepatoma cell lines. Exogenous basic fibroblast growth factor stimulated DNA synthesis and motility of hepatoma cells. The effect was more marked in poorly-differentiated hepatoma cells than in well-differentiated hepatoma cells. Fibroblast growth factor-1 expression on hepatoma cells was also more marked in poorly-differentiated hepatoma cells than in well-differentiated hepatoma cells. The stimulated motility on basic fibroblast growth factor was suppressed by an anti-fibroblast growth factor receptor-1 antibody.

CONCLUSIONS

Basic fibroblast growth factor may play an important role in the development and progression of hepatocellular carcinoma via an autocrine mechanism involving fibroblast growth factor and its receptor.

Inhibitory effects of docosahexaenoic acid on colon carcinoma 26 metastasis to the lung

Unsaturated fatty acids, including n-3 polyunsaturated fatty acids (PUFAs) such as docosahexaenoic acid (C22:6, DHA) and eicosapentaenoic acid (C20:5, EPA), and a series of n-6 PUFAs were investigated for their anti-tumour and antimetastatic effects in a subcutaneous (s.c.) implanted highly metastatic colon carcinoma 26 (Co 26Lu) model. EPA and DHA exerted significant inhibitory effects on tumour growth at the implantation site and significantly decreased the numbers of lung metastatic nodules. Oleic acid also significantly inhibited lung metastatic nodules. Treatment with arachidonic acid showed a tendency for reduction in colonization. However, treatment with high doses of fatty acids, especially linoleic acid, increased the numbers of lung metastatic nodules. DHA and EPA only inhibited lung colonizations when administered together with the tumour cells, suggesting that their incorporation is necessary for an influence to be exerted. Chromatography confirmed that contents of fatty acids in both tumour tissues and plasma were indeed affected by the treatments. Tumour cells pretreated with fatty acids in vivo, in particular DHA, also showed a low potential for lung colony formation when transferred to new hosts. Thus, DHA treatment exerted marked antimetastatic activity associated with pronounced change in the fatty acid component of tumour cells. The results indicate that uptake of DHA into tumour cells results in altered tumour cell membrane characteristics and a decreased ability to metastasize.

Reduction of tumorigenicity by alpha 3 integrin in a rhabdomyosarcoma cell line

The expression levels of integrin adhesion receptors have often been correlated with neoplastic transformation and invasiveness. To investigate more definitively the role of the integrin VLA-3 (alpha 3 beta 1) in tumor cell behavior, we transfected alpha 3 subunit cDNA into human rhabdomyosarcoma (RD) cells. Transfectants expressing high levels of alpha 3 beta 1 on their cell surface displayed an altered morphology and decreased anchorage-dependent growth in vitro. Cells expressing alpha 3 also displayed marked reduction in anchorage-independent growth in soft agar and in their ability to form tumors when injected subcutaneously into athymic nude mice. Thus, VLA-3 can repress the transformed phenotype of rhabdomyosarcoma tumor cells. Similar changes in morphology and growth characteristics were observed in cells expressing a chimeric molecule X3C4 in which the alpha 3 cytoplasmic domain had been exchanged with that of the alpha 4 integrin subunit. Therefore, alpha 3 inhibitory effects in RD cells appear not to require specific signalling through the alpha 3 cytoplasmic domain.

Expression of sulfomucins in normal mucosae, colorectal adenocarcinomas, and metastases

We have examined the expression of specific mucin antigens in tissue sections from 92 cases of colorectal carcinoma, using sulfomucin-specific monoclonal antibody (MAb) 91.9H. The expression of sulfomucins was high in normal mucosae and much lower in primary colorectal carcinoma, in metastatic lesions in lymph nodes or in liver. The intracellular localization of sulfomucins was also different among these tissues. In normal mucosae, MAb 91.9H binding was seen in the supranuclear area, presumably Golgi complexes, the luminal surface, and secretory products. In primary colorectal carcinomas and in their metastatic lesions, MAb 91.9H was preferentially localized in the cell surface and substances attached to the luminal surface of glandular structures. Analysis of the lysates of normal and tumor tissues showed that very-high-molecular-weight components contained the antigenic epitopes. The intensity of MAb 91.9H binding was lower in tumors at advanced stages than in tumors at early stages. These high-molecular-weight components were apparently reactive with MAb FH6 specific for sialyl-Le(X) (s-Le(X) structures. Histological specimens with low levels of MAb 91.9H reactivity often exhibited relatively high levels of MAb FH6 reactivity. These two mucins may have reversed expression during carcinogenesis and carcinoma progression, and this change may be related to metastatic potential.

Expression of autocrine motility factor receptor in human esophageal squamous cell carcinoma

Autocrine motility factor and its receptor (gp78) have been shown to play an important role in tumor cell migration, invasion and metastasis. We have detected gp78 expression in buffered-formalin-fixed, paraffin-embedded sections of esophageal squamous cell carcinomas using an anti-gp78 monoclonal antibody (MAb), 3F3A, and examined the relationship between gp78 expression and clinicopathological and prognostic factors. In 55 of 101 (54%) patients, gp78 was detected in the tumor cells. The frequency of gp78-positive expression was significantly associated with tumor size, infiltrative growth, depth of invasion and lymph node metastasis. The cumulative survival rate of patients with gp78 was significantly lower than that of patients without gp78. Our results suggest that autocrine motility factor receptor (gp78) expression could be a useful biomarker for malignancy grading and prognosis in patients with esophageal squamous cell carcinoma.

Tenascin-C induction by the diffusible factor epidermal growth factor in stromal-epithelial interactions

Tenascin-C, a six-armed extracellular matrix glycoprotein, is expressed in a temporally and spatially restricted pattern during carcinogenesis and invasion or metastasis of carcinoma cells in association with stromal-epithelial interactions. The human epidermoid carcinoma-derived cell lines, A431 and HEp-2, which do not express tenascin-C by themselves in vitro, do express tenascin-C after transplantation into nude mice, and transforming growth factor beta 1 (TGF-beta 1) induces them to express tenascin-C in vitro. Epidermal growth factor (EGF) induced tenascin-C in these cells more effectively (about 3.5-fold greater) than did TGF-beta 1. Hepatocyte growth factor (HGF) and platelet-derived growth factor (PDGF) had little effect on the induction of tenascin-C. EGF also induced other extracellular matrix components, fibronectin and laminin. Tenascin-C was also induced when the carcinoma cells were co-cultured with embryonic fibroblasts from mice which were homozygous for a null mutation in the tenascin-C gene, or when the conditioned medium from these cells was added. The induction of tenascin-C in the co-culture was reduced by treating the cells with antibodies against EGF or its receptor. The addition of EGF caused both cell types to disrupt their cytoskeleton and focal contacts as evidenced by the loss of stress fibers and vinculin plaques. EGF did neither induce tenascin-C nor affect the morphology in tenascin-C-nonproducing A549 carcinoma cells, which did not produce tenascin-C after transplantation. Thus, EGF induces tenascin-C in tenascin-C-nonproducing human carcinoma cells through EGF receptors. Furthermore, in stromalepithelial interactions, the diffusible factor EGF participates in the induction of human tenascin-C in these cells through EGF receptors.

Alterations in cellular gene expression without changes in nuclear matrix protein content

Cell metabolism and function are modulated in part by cell and nuclear shape. Nuclear shape is controlled by the nuclear matrix, the RNA-protein skeleton of the nucleus, and its interactions with cytoskeletal systems such as intermediate filaments and actin microfilaments. The nuclear matrix plays an important role in cell function and gene expression because active genes are bound to the nuclear matrix whereas inactive genes are not. It is unknown, however, how genes move on and off the matrix, and whether these events require compositional protein changes, i.e., alterations in protein content of the nuclear matrix, or other, more subtle alterations and/or modifications. The purpose of this investigation was to begin to determine how nuclear matrix protein composition is related to gene expression. We demonstrate that gene expression can change without apparent changes in the protein composition of the nuclear matrix in MCF10A breast epithelial cells.

Signal transduction by integrins and its role in the regulation of tumor growth

It has become clear that integrins have effects on tumorigenesis that are in addition to their role in mediating cell adhesion during invasive and metastatic processes. Integrins can transduce signals from the extracellular matrix to cell interior, via tyrosine kinases, and possibly by other mechanisms as well. These integrin mediated signals contribute to control of gene expression, to regulation of anchorage-dependence, to cell cycle transit, and to the control of tumor growth.

Detection of endogenous receptors for carbohydrate ligands in primary and metastatic human renal cell carcinoma

Frozen sections of primary and metastatic human renal cell carcinoma (RCC) were analyzed for the expression of endogenous binding sites for carbohydrates. Fluorescent neoglycoproteins, carrying chemically linked carbohydrate residues on bovine serum albumin as a carrier protein, were applied to 44 primary tumor specimens. In the majority of specimens, accessible binding sites with specificity for maltose and N-acetylgalactosamine were detected. In specimens of normal kidney no specific binding of carbohydrate ligands was observed under these experimental conditions. Specimens of both the primary tumor and a metastasis were available in 10 cases. When the expression of specific binding sites of primary tumors and metastases was compared, the respective patterns were similar with no clear gain or loss of certain lectins in the metastases. We conclude that binding sites with specificity for maltose and N-acetylgalactosamine are present on human RCC and their corresponding metastases.

Simultaneous assessment of migration and proliferation of murine fibrosarcoma cells, as affected by hydroxyurea, vinblastine, cytochalasin B, Razoxane and interferon

Using porous cell culture chambers, we have simultaneously assessed growth and locomotion of cancer cells to investigate whether certain agents affect cell motility in addition to cell division. First, cells from a murine fibrosarcoma cell line, 1.0/L1, were grown in ordinary flask cultures to determine appropriate cell inocula. Doses of agents were selected to reduce the final 4 day culture cellularity to about 50%, when present during the last two days of culturing. Secondly, the effects of these agents on cell numbers in the porous chambers and on cell migration out of the chambers ('emigration fraction') were recorded. We also examined, using a similar type of porous chamber, whether the agents could affect leucocyte chemotaxis. Hydroxyurea (an inhibitor of DNA synthesis) reduced cancer cell emigration as well as cell growth, without interfering with leucocyte chemotaxis. Cytochalasin B (a microfilament disrupting agent) inhibited cancer cell motility and growth, as well as leucocyte chemotaxis. Vinblastine (a microtubule disrupting agent), at the very low dose chosen, reduced cancer cell growth, but did not consistently affect the migration of either cell type. The experimental anti-metastasis agent Razoxane reduced growth, but had no detectable effects on motility. High doses of natural murine interferon-alpha/beta weakly inhibited both cancer cell growth and locomotion. This motivates for further studies of these and other cytokines, as treatment with agents inhibiting cancer cell locomotion might possibly prevent peri-operative spread of cancer in patients.

Expression of autocrine motility factor receptor in serum- and protein-independent fibrosarcoma cells: implications for autonomy in tumor-cell motility and metastasis

The motile response of serum-dependent (Gc-4 SD) and protein-independent (Gc-4 PF) murine fibrosarcoma cells to monoclonal antibody (MAb) that binds to gp78 a cell-surface receptor (M(r) 78,000) for an autocrine motility factor (AMF) was analyzed. The Gc-4 PF cells responded to the anti-gp78 by increased motility in vitro (3-fold) and increased lung colonization in vivo (8- to 20-fold), while the serum-dependent counterpart failed to respond to motile stimulation both in vitro and in vivo. Immuno-analysis of cell-surface expression and cell extracts revealed a smaller amount of gp78 in Gc-4 SD cells than in Gc-4 PF cells. Both cell lines secrete an equal amount of AMF to the culture media. Our results suggest that protein-free culture of Gc-4 PF cells is associated with high response to AMF and with high expression of its receptor, and that autonomous motile regulation may play a role in tumor dissemination.

Differences in chemotaxis to fibronectin in weakly and highly metastatic tumor cells

We have examined the chemotactic ability of tumor cell lines with different metastatic potential to plasma fibronectin in Transwell chamber assay. Human renal carcinoma cells with highly metastatic potential, SN12 C-2, chemotactically migrated to fibronectin (10 micrograms/ml) about three-fold more strongly than weakly metastatic SN12 C-4 cells. Similarly, murine melanoma B16-BL6 cells (highly metastatic) showed higher motility to soluble fibronectin in comparison with weakly metastatic B16-F1 cells. Anti-VLA-alpha 3 and beta 1 antibodies potently blocked the chemotaxis of both highly and weakly metastatic cells (SN12 C-2 and C-4) to fibronectin. This implies that the migration of both C-2 and C-4 cells to fibronectin is basically mediated by VLA-3 receptor. In contrast, the anti-VLA-alpha 5 antibody and RGDS peptide significantly inhibited the chemotaxis of SN12 C-2 cells to fibronectin, but did not affect weakly metastatic SN12 C-4 cells. These results suggest that the chemotactic ability to fibronectin positively correlates with the metastatic potential in SN12 and B16 cell lines, and that VLA-5 receptor is concerned in the motility of highly metastatic SN12 C-2 cells to soluble fibronectin.

Suppression of tumorigenicity in transformed cells after transfection with vinculin cDNA

Transfection of chicken vinculin cDNA into two tumor cell lines expressing diminished levels of the endogenous protein, brought about a drastic suppression of their tumorigenic ability. The SV-40-transformed Balb/c 3T3 line (SVT2) contains four times less vinculin than the parental 3T3 cells, and the rat adenocarcinoma BSp73ASML has no detectable vinculin. Restoration of vinculin in these cells, up to the levels found in 3T3 cells, resulted in an apparent increase in substrate adhesiveness, a decrease in the ability to grow in soft agar, and suppression of their capacity to develop tumors after injection into syngeneic hosts or nude mice. These results suggest that vinculin, a cytoplasmic component of cell-matrix and cell-cell adhesions, may have a major suppressive effect on the transformed phenotype.

Chemotaxis of metastatic tumor cells: clues to mechanisms from the Dictyostelium paradigm

Amoeboid movement, and in some cases, amoeboid chemotaxis, is a key step in tumor metastasis. The high degree of conservation in signal transduction pathways and motile machinery in eukaryotic cells suggests that insights and molecular probes developed from the study of these processes in easily manipulated experimental model systems will be applicable directly to experimentally intractable tumor cells. One such model system, Dictyostelium discoideum, is discussed in terms of the molecular events involved in amoeboid chemotaxis. The application of insights and assays developed with Dictyostelium to early events in the chemotaxis of Lewis lung carcinoma cells is reviewed.

Overexpression of vinculin suppresses cell motility in BALB/c 3T3 cells

The content of vinculin, a cytoplasmic protein found in focal contacts and cell-cell junctions, was increased in BALB/c 3T3 cells by gene transfection. The vinculin expressed from the full length chicken cDNA, incorporated into focal contacts and its pattern was identical to that of the endogenous protein. Cells stably expressing vinculin by 20% over the endogenous level had altered locomotory properties. In these cells, the ability to migrate into a wound formed in a confluent monolayer and the locomotion of individual cells were drastically reduced. The results provide direct evidence that cell locomotion can be regulated by modulating vinculin expression.

Resistance to DNA denaturation in irradiated Chinese hamster V79 fibroblasts is linked to cell shape

Exponentially growing Chinese hamster V79-171b lung fibroblasts seeded at high density on plastic (approximately 7 x 10(3) cells/cm2) flatten, elongate, and produce significant amounts of extracellular fibronectin. When lysed in weak alkali/high salt, the rate of DNA denaturation following exposure to ionizing radiation is exponential. Conversely, cells plated at low density (approximately 7 x 10(2) cells/cm2) on plastic are more rounded 24 h later, produce little extracellular fibronectin, and display unusual DNA denaturation kinetics after X-irradiation. DNA in these cells resists denaturation, as though "constraints" to DNA unwinding have developed. Cell doubling time and distribution of cells in the growth cycle are identical for both high and low density cultures as is cell survival in response to radiation damage. The connection between DNA conformation and cell shape was examined further in low density cultures grown in conditioned medium. Under these conditions, cells at low density were able to elongate, and DNA denaturation of low density cultures was identical to that of high density cultures. Conversely, cytochalasin D, which interferes with actin polymerization causing cells to "round up" and release fibronectin, allowed development of constraints in high density cultures. These results suggest that DNA conformation is sensitive to changes in cell shape which result when cells are grown in different environments. However, these changes in DNA conformation detected by the DNA unwinding assay do not appear to play a direct role in radiation-induced cell killing.

Tumor cell autocrine motility factor receptor

The ability to locomote and migrate is fundamental to the acquisition of invasive and metastatic properties by tumor cells. Autocrine motility factor (AMF) is a cytokine produced by various tumor cells which stimulates their in vitro motility and in vivo lung-colonizing ability. AMF stimulates cell motility via a receptor-mediated signalling pathway. Signal transduction following binding of AMF to its receptor, a cell surface glycoprotein of 78 kD (gp78), is mediated by a pertussis toxin sensitive G protein, inositol phosphate production and the phosphorylation of gp78. AMF induces gp78 internalization to intracellular tubulovesicles and transport to the leading edge stimulating pseudopodial protrusion and cell motility.

The invasive phenotypes

The expression of the invasive (I+ or I-) phenotypes determines cancer metastasis (M+ or M- phenotype). The invasive (I+ or I-) phenotypes can be divided according to time and site of expression into subphenotypes, which can be assessed separately. At various sites along the metastatic pathway the expression of the I phenotypes can be accompanied by the presence of uncontrolled growth (G+ phenotype) or its absence (G- phenotype). Various combinations of the I and G phenotypes determine the behaviour of metazoan or parasitic cells under normal, pathological non-neoplastic and neoplastic conditions. Although the G+I+M+ combination correlates with full malignancy, the sequence of events leading to the acquisition of these phenotypes during tumor development is not clear. Conditional invasion in experimental systems indicates that a tumor may be invasive and metastatic when part of its population temporarily expresses the I+ phenotype. These experiments further stress the importance of the tumor-host ecosystem for the regulation of the I phenotypes. As distinct from some parasites, the invasive morphotype of vertebrate cells cannot be simply identified. Nevertheless, within the tumor-host ecosystem morphological correlates of the activities of invasive cells may be recognized. They reflect one or more of the I+ functions, namely: motility; loss of homotypic cell-cell adhesion; establishment of alternative cell-substrate and heterotypic cell-cell adhesion; breakdown of extracellular matrices. These functions are not exclusive for I+ tumor cells, and neither are the molecular markers investigated so far. Oncogene activation leads mainly to G+ expression, and in this way serves as a signal amplifier for the I and M phenotypes. Attractive candidate molecular markers of I phenotypes are: regulators of hydrolase activities; cell-cell adhesion molecules; cell surface receptors. From data presently available, we hypothesize that invasion depends upon the balance between and I+ and an I- pathway, with both pathways being sensitive to stimulation inhibition.

Profiles of human melanoma cell surface proteins: effects of culturing on two different substrates

Three human melanoma cell lines of differing invasive and metastatic potentials were cultured on either a plastic surface or a denuded amniotic basement membrane, and alterations in their cell surface proteins, invasive profiles, and the presence or absence of the 69 Kd high-affinity metastasis-associated laminin receptor were examined. Our data indicate that the labeled, precipitable cell surface proteins are different from the three cell lines when they are cultured on the same substrate, and change when the cells are cultured on a different substrate. Furthermore, the invasive potential (as measured in the in vitro Membrane Invasion Culture System) is decreased for all of the cell lines after culturing the cells on a basement membrane matrix compared to a plastic surface. Finally, we show that the 69 Kd high-affinity metastasis-associated laminin receptor can be isolated from all three cell lines cultured on the two different substrates by labeling the cell surface with trinitrobenzene sulfonic acid and immunoprecipitating these targeted proteins.

Molecular oncogenetics of metastasis

Metastasis is a complex non-stochastic process that is most likely the result of genetic and epigenetic interactions of a wide variety of genes. The search for a single gene which can encompass such a pleiotropic response as to account for the observed phenotypic characteristics of metastatic tumour populations has been unsuccessful. Particular studies involving gene transfection, subtractive hybridisation and cell fusion are beginning to identify specific genes which contribute to metastasis in some cell types. However, such analyses are complicated by the inherent genetic instability and phenotypic heterogeneity present in tumour populations. A more detailed understanding of the metastatic process may require an abandoning of current generalised approaches to metastasis in favour of concentrating on key components of the metastatic cascade such as adhesion and invasion.

Membrane fluidity affects tumor-cell motility, invasion and lung-colonizing potential

Membrane fluidity, determined by steady-state fluorescence polarization measurements, was correlated with metastatic capacity of murine tumor-cell lines. A correlation was observed in cell lines with different metastatic potential, and was confirmed when their lung-colonizing ability was modulated by alteration of either the membrane lipid composition or the culture conditions. Two cellular functions, motility and basement membrane invasion, were affected by the membrane lipid composition, and might explain the role of membrane fluidity observed in cancer metastasis.

Interactions between cancer cells and the microvasculature: a rate-regulator for metastasis

Hematogenous metastasis is a major consideration in the staging, treatment and prognosis of patients with cancer. Key events affecting hematogeneous metastasis occur in the microvasculature. This is a brief, selective review of some interactions involving cancer cells and the microvasculature in pathologic sequence, specifically: (1) intravasation of cancer cells; (2) the arrest of circulating cancer cells in the microvasculature; (3) cancer cell trauma associated with arrest; (4) microvascular trauma; (5) the inflammatory; and (6) the hemostatic coagulative responses associated with arrest, and finally (7) angiogenesis, leading to tumor vascularization. The evidence shows that through a series of complex interactions with cancer cells, the microvasculature acts as a rate-regulator for the metastatic process, in addition to providing routes for cancer cell dissemination and arrest sites for cancer cell emboli.