Use of a reconstituted basement membrane to study the invasiveness of tumor cells

Cell migration and invasion assays

A number of in vitro assays have been developed to study tumor cell motility. Historically, assays have been mainly monocellular, where carcinoma cells are studied in isolation. Scratch assays can be used to study the collective and directional movement of populations of cells, whereas two chamber assays lend themselves to the analysis of chemotactic/haptotactic migration and cell invasion. However, an inherent disadvantage of these assays is that they grossly oversimplify the complex process of invasion, lacking the tumor structural architecture and stromal components. Organotypic assays, where tumor cells are grown at an air/liquid interface on gels populated with stromal cells, are a more physiologically relevant method for studying 3-dimensional tumor invasion.

Survivin is a potential mediator of prostate cancer metastasis

PURPOSE

We examined whether Survivin expression is associated with an increased risk of metastasis in prostate cancer.

METHODS AND MATERIALS

A total of 205 patients with T1 (23%) and T2 (77%) prostate cancer were treated with conventional external beam radiation therapy from 1991 to 1993 at the Massachusetts General Hospital. Of the patients, 62 had adequate and suitable-stained tumor material for Survivin analysis. Median follow-up was 102 months (range, 5-127 months). Distant failure was determined on the basis of clinical criteria. In preclinical studies, replication-deficient adenovirus encoding phosphorylation-defective Survivin Thr34→Ala dominant-negative mutant pAd-S(T34A) or short hairpin RNA (shRNA) was used to inhibit Survivin in prostate cancer models, and the cell motility, morphology, and metastasis were investigated.

RESULTS

Our correlative data on men with early-stage (T1/T2) prostate cancers treated at Massachusetts General Hospital by definitive radiotherapy indicated that overexpression of Survivin (positive staining in ≥10% cells) was associated with a significantly increased risk for the subsequent development of distant metastasis (p = 0.016) in the univariate analysis. In the multivariate analysis, overexpression of Survivin remained an independent predictor of distant metastasis (p = 0.008). The inhibition of Survivin dramatically inhibited invasiveness of prostate cancer cells in the in vitro invasion assay and spontaneous metastasis in the Dunning prostate cancer in vivo model. Furthermore, attenuation of Survivin resulted in changes in the microtubule cytoskeleton, loss of cellular polarity, and loss of motility.

CONCLUSIONS

This study suggests that Survivin may be a potentially important prognostic marker and promising therapeutic target in metastatic prostate cancer.

Acetylsalicylic acid regulates MMP-2 activity and inhibits colorectal invasion of murine B16F0 melanoma cells in C57BL/6J mice: effects of prostaglandin F(2)alpha

Epidemiological studies indicate that acetylsalicylic acid may reduce the risk of mortality due to colon cancers. Metastasis is the major cause of cancer death. Matrix metalloproteinases (MMPs) play important roles in tumor invasion regulation, and prostaglandin F(2)alpha (PGF(2)alpha) is a key stimulator of MMP production. Thus, we investigated whether acetylsalicylic acid regulated MMP activity and the invasion of cancer cells and whether PGF(2)alpha attenuated acetylsalicylic acid-inhibited invasion of cancer cells. Gelatin-based zymography assays showed that acetylsalicylic acid inhibited the MMP-2 activity of B16F0 melanoma cells. Matrigel-based chemoinvasion assays showed that acetylsalicylic acid inhibited the invasion of B16F0 cells. Acetylsalicylic acid can inhibit PGF(2)alpha synthesis and PGF(2)alpha is a key stimulator of MMP-2 production. Our data showed that PGF(2)alpha treatment attenuated the acetylsalicylic acid-inhibited invasion of B16F0 cells. In animal experiments, acetylsalicylic acid reduced colorectal metastasis of B16F0 cells in C57BL/6J mice by 44%. Our results suggest that PGF(2)alpha is a therapeutic target for metastasis inhibition and acetylsalicylic acid may possess anti-metastasis ability.

RRR-alpha-tocopheryl succinate inhibits human prostate cancer cell invasiveness

RRR-alpha-tocopheryl succinate (alpha-vitamin E succinate, VES), one of the vitamin E derivatives, can effectively inhibit the proliferation of human prostate cancer cells. However, little is known about its effect on prostate cancer cell invasive ability. Tumor metastasis is a complex process and the extracellular matrix (ECM) is the first barrier that tumor cells encounter. Therefore, we tested the effect of VES on the invasion of different prostate tumor cells, PC-3, DU-145, and LNCaP, through Matrigel, a reconstituted ECM, using an in vitro cell invasion assay. The invasion of PC-3 and DU-145 cells through Matrigel was inhibited by 20 microM VES after treating for 24 h. The condition did not alter cell survival, cell cycle, cell adhesion or cell motility. We further investigated whether the ability of VES to inhibit prostate cancer cell invasiveness was associated with its ability to inhibit the activity of matrix metalloproteinases (MMPs), the key enzymes in the proteolysis of basement membrane during invasion. PC-3 and DU-145 cells that were treated with VES showed a significant reduction in the levels of MMP-9 in the culture medium. In contrast, LNCaP cells, which did not secrete MMP-9, were poorly invasive in Matrigel and were hardly affected by treatment with VES. This is the first report suggesting that VES inhibits human prostate cancer cell invasiveness and the reduction of secreted MMP-9 activity could be one of the contributory factors, which points to the potential use of VES in the prevention and therapy of prostate cancer invasion.

Antagonistic and agonistic effects of quinazoline tyrosine kinase inhibitors on mutant EGF receptor function

A mutated form of the EGF receptor (EGFRvIII), resulting from deletion of exons 2-7, is an oncogenic protein that is expressed in multiple human tumors. This mutation induces ligand-independent activation of the EGFR tyrosine kinase and thereby can initiate unregulated cell growth and tumorigenesis. Thus, inhibition of the kinase activity of EGFRvIII is a potential means of suppressing its oncogenic properties. Certain tyrosine kinase inhibitors (tyrphostins) specifically inhibit the wild-type EGFR and thereby inhibit tumor growth both in vitro and in vivo. We demonstrate that the quinazoline tyrphostins AG 1478 and AG 1517 can suppress morphologic transformation of cell lines by EGFRvIII. Quinazolines were found to inhibit receptor autophosphorylation and signaling through MAP kinase, but had minimal effects on association of EGFRvIII with Grb2/SOS. Low concentrations of quinazoline also increased receptor dimerization and phosphotyrosine content. This was associated with increases in colony formation in soft agar and increased invasion through matrigel for AG 1478. Thus, both AG 1478 and AG 1517 can inhibit multiple EGFRvIII signaling pathways, but at low concentrations AG 1478 can enhance colony formation, presumably related to augmented homodimerization of the receptor and activation of downstream signaling.

Abciximab inhibits the migration and invasion potential of human coronary artery smooth muscle cells

In the EPIC trial, high-risk patients received the integrin receptor antagonist abciximab v placebo during and for 12 h following percutaneous coronary intervention with a significant 23% decrease of repeat revascularisation at 6 months. However, EPILOG and CAPTURE trials could not confirm these promising long-term results. Recently presented data from the EPISTENT trial suggested a beneficial effect of abciximab on restenosis in patients with diabetes. Based on these divergent results the aim of this study was to test whether alpha v beta 3 receptor blockade by abciximab could cause inhibition of human coronary smooth muscle cell (hcSMC) proliferation, migration, and invasion which represent crucial steps during restenosis development. In contrast to quiescent hcSMCs, proliferating cells were capable to migrate towards chemoattractive stimuli and even capable to invade through a basement membrane equivalent. Abciximab and LM609, an alpha v beta 3 specific inhibiting antibody, caused only a modest dose-dependent inhibition of hcSMC proliferation. On the contrary, the chemotactic and invasive potential of hcSMCs was significantly inhibited by abciximab administration 24 h prior to and during migration. (IC(50)=33.0 microg/ml for chemotaxis and IC(50)=0.5 microg/ml for invasion). For LM609 similar results were obtained. Administration of the drugs just during migration without pretreatment inhibited migration equally but invasion to a lower extent (abciximab: IC(50)=32.6 microg/ml for chemotaxis and IC(50)=44.9 microg/ml for invasion; LM609 IC(50)=3.1 microg/ml for chemotaxis and IC(50)=2.0 microg/ml for invasion). The attachment to the extracellular matrix proteins collagen I, collagen IV, laminin and vitronectin was not influenced. Pretreatment for 24 h with abciximab or LM609 did not cause a downregulation of the alpha v beta 3-integrin receptor. The results of this study indicate that the alpha v beta 3 antagonist abciximab is a potent inhibitor of hcSMC migration and invasion which could explain the observed lower reintervention rate after PTCA and stent implantation.

Invasion of human follicular thyroid carcinoma cells in an in vivo invasion model

Models that demonstrate histological invasion of extracellular matrix barriers by tumor cell lines are useful for assessing new methods to treat or prevent tumor metastasis. An in vivo invasion model using acellular human dermal matrix has been described in a murine squamous cell carcinoma line. The present study examined the application of this tumor invasion model to another epithelial cell line derived from a different species. A human follicular thyroid carcinoma cell line, known to be invasive by other assays, was grown on the dermal-epidermal basement membrane surface of human acellular dermal matrix in culture and then grafted in athymic mice. Immunohistochemical staining of type IV collagen was used to identify the basement membrane and invasion was determined as penetration of the basement membrane by tumor cells. Identification of the human tumor cells in the in vivo grafts was done by in situ hybridization with species specific probes. FTC-133 tumor cells did not invade the matrix after 4 weeks of growth in in vitro culture, but there was extensive loss of the basement membrane and infiltration of the tumor cells into the dermis after 2 weeks growth in vivo. This study suggests that the in vivo dermal matrix model of invasion is applicable to a broad range of epithelial carcinoma cell lines to study their capability to penetrate basement membrane. A model such as this may be useful for studying the local effects of genetic manipulations of implanted tumor cell populations, leading to the development of therapeutic agents that block invasion.

Thyroid stimulating hormone and N6-2'-O-dibutyryladenosine 3'-5'-cyclic monophosphate decrease 110,000-130,000 M(r) tyrosine-phosphorylated substrate in rat thyroid cells

By immunoblotting using monoclonal antibodies against phosphotyrosine, thyroid stimulating hormone (TSH)-induced changes in tyrosine phosphorylation of intracellular proteins in earlier passages of rat thyroid cells (FRTL-5) were studied. TSH and N6-2'-O-dibutyryladenosine 3'-5'-cyclic monophosphate (Bt2cAMP) decreased the phosphotyrosine content of 110,000-130,000 M(r) substrate (p120) in parallel with a morphological change in FRTL-5 cells. Insulin-like growth factor-I (IGF-I) or phorbol 12-myristate 13-acetate (PMA) only showed an attenuated reaction compared with that of TSH or Bt2cAMP. Further, sodium orthovanadate (a protein tyrosine phosphatase inhibitor) could not inhibit this reaction. These data suggest possible inhibitory effects of TSH and adenosine 3'-5'-cyclic monophosphate (cAMP) on tyrosine kinases that act on this substrate.

Cytokine control of cell motility: modulation and mediation by the extracellular matrix

Cytokines are multifunctional regulators of cell behaviour affecting such diverse activities as cell proliferation, gene expression and motility. Matrix macromolecules influence a similarly wide range of cell functions. A review of the available literature suggests that cytokines may affect cell motility by (a) directly influencing the motility apparatus, and (b) indirectly as a consequence of the altered expression of genes coding for matrix macromolecules, their respective cell surface receptors and matrix degrading enzymes and their inhibitors. Conversely, the composition and supramolecular organisation of the matrix plays a central role in defining cellular response to potentially multifunctional cytokines. Such complex and reciprocal interactions between cytokines and the matrix elicit both positive and negative reiterative feedback loops which must be taken into account when interpreting the results of migration assays in vitro and extrapolating them to in vivo processes.