Circulating endothelial progenitor cells and depression: a possible novel link between heart and soul.

Although depression is known to be an independent risk factor for cardiovascular disorders, the mechanisms behind this connection are not well understood. However, the reduction in the number of endothelial progenitor cells (EPCs) in patients with cardiovascular risk factors has led us to hypothesize that depression influences the number of EPCs. EPCs labeled with CD34, CD133 and vascular endothelial growth factor receptor-2 (VEGFR2) antibodies were counted by flow cytometry in the peripheral blood (PB) of 33 patients with a current episode of major depression and of 16 control subjects. Mature (CD34+/VEGFR2+) and immature (CD133+/VEGFR2+) EPC counts were decreased in patients (vs controls; P<0.01 for both comparisons), and there was a significant inverse relationship between EPC levels and the severity of depressive symptoms (P<0.01 for both EPC phenotypes). Additionally, we assayed the plasma levels of VEGF, C-reactive protein (CRP) and tumor necrosis factor (TNF)-alpha and observed significantly elevated TNF-alpha concentrations in patients (vs controls; P<0.05) and, moreover, a significant inverse correlation between TNF-alpha and EPC levels (P<0.05). Moreover, by means of a quantitative RT-PCR approach, we measured CD34, CD133 and VEGFR2 mRNA levels of PB samples and found a net trend toward a decrease in all the investigated EPC-specific mRNA levels in patients as compared with controls. However, statistical significance was reached only for VEGFR2 and CD133 levels (P<0.01 for both markers). This is the first paper that demonstrates evidence of decreased numbers of circulating EPCs in patients with a current episode of major depression.

Expression and secretion of neuroleukin/phosphohexose isomerase/maturation factor as autocrine motility factor by tumor cells.

The results obtained from fragmented protein microsequencing have suggested that autocrine motility factor (AMF), a tumor-secreted Mr 55,000 cytokine that regulates cell motility in vitro as well as invasion and metastasis in vivo, is the neuroleukin (NLK)/phosphohexose isomerase (PHI)/maturation factor (MF) polypeptide. Here, we cloned, sequenced, and studied the expression, secretion, and distribution of AMF/NLK/PHI/MF in neoplastic and their normal counterpart cells. Although both normal and neoplastic cells express the gene product, overexpression associated with selective secretion of the protein was observed only in tumor cells. The cDNA sequences of AMF/NLK/PHI/MF found in both human cancer and normal cells were found to be identical, suggesting that its secretion by neoplastic cells is independent of mutation or alternative splicing. Immunohistochemical visualization has depicted AMF/NLK/PHI/MF to be localized into tubular-like vesicles, diffusely distributed throughout the cytoplasm and not colocalized with any particular cytoskeletal network. Confocal microscopic imaging had shown a partial colocalization between AMF and its receptor (Mr 78,000 glycoprotein), especially on the malignant cell surface periphery. The results suggest that extracellular AMF activity may be a result of the product of intracellular cleavage of a precursor polypeptide, which is overexpressed and selectively secreted through a nonclassical secretory mechanism by neoplastic cells.

Localization of sunitinib, its metabolites and its target receptors in tumour-bearing mice: a MALDI-MS imaging study.

BACKGROUND AND PURPOSE: The clinical effects of anti-angiogenic agents remain controversial. Therefore, elucidating the pharmacological properties of these compounds is a pivotal issue. EXPERIMENTAL APPROACH: The effects of treatment with sunitinib on tumour and normal tissues of mice bearing C-26 adenocarcinoma cells were analysed by matrix-assisted laser desorption ionization MS imaging (MALDI-MSI). Expression of the key targets of sunitinib--angiogenic receptors--was studied by immunofluorescent labelling. KEY RESULTS: MALDI-MS assays showed that sunitinib and its fragment ions were present throughout tumour and normal tissues. Major metabolites were identified in blood and solid tissues, while minor drug metabolites were detectable only in blood. Tumour growth and intratumour VEGF receptor-2 expressions were significantly reduced in sunitinib-treated mice, while the expression of the other targeted receptors, PDGF receptor -α or -ß and fibroblast growth factor receptor-1, remained unaffected. Within tumour tissue, the close proximity of sunitinib metabolites to the precursor ion suggested in situ metabolism of the administered drug. There were intratumour areas where the signal intensity of sunitinib correlated with expression of VEGF receptor-2. CONCLUSIONS AND IMPLICATIONS: This is the first study that demonstrates MALDI-MSI is a versatile platform to study the intratumour localization of an unlabelled anti-angiogenic drug. The combination of MALDI-MSI and immunofluorescence analysis can provide further insights into the molecular interaction of drug compounds and their targets within tumour tissue.

Organ-specificity of the extravasation process: an ultrastructural study.

UNLABELLED: The process of extravasation of the high metastatic Lewis lung carcinoma line was examined in different organs. Four of the five organs (liver, lungs, brain and adrenals) represent the most frequent metastatic sites in humans. In the case of each organ 150-350 tumor cells were analysed. The interaction of tumor cells with endothelial cells and the basement membrane showed significant differences between the organs. In the liver and lungs, endothelial cells were found to migrate onto the surface of the tumor cells, resulting in the removal of tumor cells from the circulation. The process was initiated by development of cytoplasmic projections on the luminal surface of the endothelial cells. In the liver only half of the tumor cells showed basement membrane degradation even after 24 h, although 6 h after injection 40% of the tumor cells were sequestered from the circulation. In the adrenals and brain, tumor cells were not covered by endothelial cells instead, limited retraction of endothelial cells was followed by penetration of the basement membrane. In the kidney both types of tumor cell-endothelial cell interactions were observed, but the process of extravasation was not completed, stopping as the tumor cells reached the basement membrane or the mesangial matrix. The time course of tumor cell extravasation also showed significant differences between the organs. The process was most rapid in case of the liver and adrenals. By 6 h 40-50% of the tumor cells were in the process of extravasation or were in an extracapillary position. These organs are preferential metastatic sites of this tumor line. The time of extravasation was much longer in the other organs (lungs 16 h, brain 48 h), for which this tumor line shows no preference. CONCLUSIONS: (1) Type and duration of tumor cell extravasation differ between the organs. (2) The time needed to reach extraluminal position, but not the type of extravasation correlates with the organ preference. (3) Endothelial cells of the lungs and liver can play a much more active role in the process of extravasation than previously suggested. (4) Tumor cells can complete the metastatic process without reaching a complete extracapillary position; contact with the basement membrane or extracellular matrix seems to be sufficient.

Endothelialization of embolized tumor cells during metastasis formation.

The reaction of the endothelial barrier to tumor cell extravasation has been studied using electron microscopy. The model system was pulmonary metastases produced by intravenous injection of B16-F10 melanoma cells. A striking difference was observed in the behavior of the endothelial lining of arterioles versus that of capillaries. In capillaries, partial retraction of endothelial cells took place following the attachment of tumor cells. The tumor cells then immediately attached to the basement membrane and the basolateral surface of the retracted endothelial cells. The endothelial cells extended to cover the tumor cells prior to complete extravasation. In the arterioles, on the other hand, endothelial retraction did not occur following tumor cell attachment. Instead the attached tumor cell emboli became encompassed by endothelial cells, outgrowing from the intact endothelial lining of the arteriole. Owing to the proliferation of the tumor cells, tumor colonies encompassed by endothelial cells expanded within the lumen. When these intravascular growths completely filled the lumen, the tumor cells extravasated from the vessel only after the original endothelial layer became mechanically disrupted and the tumor cells thereby came into contact with the basement membrane.

Demonstration of the organ preference of liver selected 'high metastatic' Lewis lung tumor cell line.

The experimental metastasis patterns of 'low metastatic' Lewis lung tumor (LLT) and liver selected 'high metastatic' LLT-HH were studied following their arterial dissemination. In previous reports it was shown that both tumor lines develop metastases only in the first encountered organ. Here the liver preference of the liver selected cell line is demonstrated. The model of two LLT cell lines can provide experimental evidence for both the 'mechanical' and 'seed and soil' theories of metastasis formation, depending on the site of tumor cell injection.

Autocrine motility factor (neuroleukin, phosphohexose isomerase) induces cell movement through 12-lipoxygenase-dependent tyrosine phosphorylation and serine dephosphorylation events.

Autocrine motility factor (AMF) is one of the motility cytokines regulating tumor cell migration, therefore identification of the signaling pathway coupled with it has critical importance. Previous studies revealed several elements of this pathway predominated by lipoxygenase-PKC activations but the role for tyrosine kinases remained questionable. Motility cytokines frequently have mitogenic effect as well, producing activation of overlapping signaling pathways therefore we have used B16a melanoma cells as models where AMF has exclusive motility effect. Our studies revealed that in B16a cells AMF initiated rapid (1-5 min) activation of the protein tyrosine kinase (PTK) cascade inducing phosphorylation of 179, 125, 95 and 40/37 kD proteins which was mediated by upstream cyclo- and lipoxygenases. The phosphorylated proteins were localized to the cortical actin-stress fiber attachment zones in situ by confocal microscopy. On the other hand, AMF receptor activation induced significant decrease in overall serine-phosphorylation level of cellular proteins accompanied by serine phosphorylation of 200, 90, 78 and 65 kd proteins. The decrease in serine phosphorylation was independent of PTKs, PKC as well as cyclo- and lipoxygenases. However, AMF induced robust translocation of PKCalpha to the stress fibers and cortical actin suggesting a critical role for this kinase in the generation of the motility signal. Based on the significant decrease in serine phosphorylation after AMF stimulus in B16a cells we postulated the involvement of putative serine/threonine phosphatase(s) upstream lipoxygenase and activation of the protein tyrosine kinase cascade downstream cyclo- and lipoxygenase(s) in the previously identified autocrine motility signal.

The antimetabolite Tiazofurin (TR) inhibits glycoconjugate biosynthesis and invasiveness of tumour cells.

We investigated the effect of Tiazofurin (TR-2-beta-D-furanosylthiazole-4-carbamide) on tumour cell invasion using metastatic 3LL-HH murine lung carcinoma and HT168-M1 human melanoma as experimental models. TR pretreatment of 3LL-HH cells, in a dose range of 15-60 microM, caused inhibition of cell proliferation, adhesion to plastic and extracellular matrix proteins. The TR-induced altered matrix interactions of 3LL-HH cells were reflected in decreased migration through matrix-covered filters. Analysis of the expression of certain invasion markers indicated that TR suppressed the expression of alpha v beta 3 integrin and MMP2 metalloproteinase. Biochemical studies indicated that 24 h 60 microM TR treatment of 3LL-HH cells inhibited glycosylation of a wide range of glycoproteins with the most pronounced effect on proteoglycans. TR pretreatment of 3LL-HH tumour cells resulted in the loss of lung colonisation potential in vivo. Furthermore, in vivo TR treatment inhibited the formation of liver metastases of 3LL-HH murine carcinoma. TR treatment also induced inhibition of integrin and MMP2 expression, migration and liver colonisation of the human melanoma HT168-M1 cell line. Since the TR concentration which inhibited various cellular functions was much lower for cell adhesion and lung colonisation than for cell proliferation, we suggest that the predominant effect of TR is the inhibition of metastasis in these model systems. We also suggest that both the effect of TR on tumour cell proliferation and on extracellular matrix interaction contribute to its remarkable antimetastatic potential in vivo.

Methamphetamine-induced neurotoxicity in BALB/c, DBA/2N and C57BL/6N mice.

Repeated administration of methamphetamine (METH; 2 and 4 mg/kg, s.c. four times every 2 h) caused hyperthermia and a dose-dependent depletion of striatal dopamine levels 3 days after the METH-treatment in both BALB/cAnNCrj (BALB) and DBA/2NCrj (DBA) mice, but these responses were lower in C57BL/6NCrj (C57BL) mice. An acute decrease of striatal dopamine levels 30 min after the last injection of METH (4 mg/kg) was observed in both BALB and DBA mice, while an increase in dopamine was observed in C57BL mice. Striatal 3-methoxytyramine levels were drastically increased in both DBA and C57BL mice after this same treatment. Moreover, pretreatment with the superoxide dismutase inhibitor, diethyldithiocarbamate (200 mg/kg, i.p.) exacerbated the METH (4 mg/kg)-induced striatal dopamine-depletion in BALB mice. In addition, pretreatment with an inhibitor of poly(ADP-ribose) polymerase, benzamide (160 mg/kg, s.c.), significantly attenuated the METH (4 mg/kg)-induced striatal dopamine depletion in both BALB and DBA mice. These results suggest that both BALB and DBA mice possess a higher sensitivity to the METH-induced striatal dopaminergic neurotoxicity compared to C57BL mice. In addition, the striatal dopaminergic neurons of BALB mice may be more vulnerable to METH-induced oxidative stress as compared to that in C57BL mice.

Ectopic alphaIIbbeta3 integrin signaling involves 12-lipoxygenase- and PKC-mediated serine phosphorylation events in melanoma cells.

Megakaryocytic genes such as alphaIIbbeta3 can be expressed by malignant cells as part of the disturbances in their gene regulation. However, the function of the gene product greatly depends on the interaction of the ectopic protein with the new environment. The outside-in signaling of the ectopically expressed alphaIIbbeta3 integrin was studied in B16a murine melanoma cells using a monoclonal antibody, specifically directed to the activated conformation of alphaIIbbeta3, PAC-1 and the physiological ligand, fibrinogen. Ligation of alphaIIbbeta3 induced down-regulation of FAK but serine phosphorylation of three protein bands, 20/21, 85 and 140 kDa within 1-15 min. Flow cytometry indicated that the ligation of the receptor in B16a cells induces approximately 50% increase in phosphoserine positive cells within 5-15 min. 12-lipoxygenase is placed downstream in the signaling pathway, since ligation of alphaIIbbeta3 induces 12-HETE production within 5 min and pretreatment of tumor cells with select lipoxygenase inhibitior, Baicalein, prevents the increase in serine phosphorylation. Confocal microscopy of adherent tumor cells demonstrated rearrangement of actin filaments upon alphaIIbbeta3 ligation paralleled by downregulation of p125FAK and phoshotyrosine+ adhesion plaques and translocation of PKCalpha to stress fibers and cortical actin. PKC appears to be the major effector serine kinase of the alphaIIbbeta3-coupled signaling pathway, since pretreatment of tumor cells with a select PKC inhibitor, Calphostin C, prevents the ligation-induced serine phosphorylation. Previous studies have indicated a role for the 12-lipoxygenase-PKC signaling pathway in platelet aggregation as well as tumor invasion, therefore the involvement of this cascade in the signaling of the ectopic alphaIIbbeta3 integrin may partially explain its role in tumor progression.

Two human melanoma xenografts with different metastatic capacity and glycosaminoglycan pattern.

Two human melanoma xenografts were compared with respect to their in vivo growth and metastatic potentials as well as glycosaminoglycan patterns. The less differentiated HT 168 tumor showed faster growth at primary sites and a more pronounced capacity for metastasis into the liver. Although chondroitin sulfate was the dominant glycosaminoglycan subtype in both tumors, the more invasive xenograft had a higher heparan sulfate/chondroitin sulfate (HS/CS) ratio. We suggest that tumor progression is influenced by this ratio in this human melanoma system.

Oral administration of a trace element preparation and zinc inhibit liver metastasis of 3LL-HH murine tumor cells.

A trace element preparation (TEP-Beres Drops Plus) was given to liver metastasizing 3LL-HH tumor bearing mice in the presence and after the removal of the primary spleen tumor. In both models when TEP was provided daily and orally in a dose range of 100-5,000 microgram/kg, the number of liver metastasis decreased at an end-point of day 14 and TEP also had inhibitory effect on the primary tumor. The antitumor action proved to be dependent on tumor burden. There was no change in body weight, size distribution of metastases and in the life span of mice. Zn++ could be one of the antimetastatic components among the trace elements. This is the first report on the antimetastatic effect of trace elements in an experimental tumor model.

Ultrastructural studies on the lung colonization by nonmetastatic rat tumor cells.

The events during the settlement of BSp73AS (AS) tumor cells in the syngeneic rat lung are described. Although AS cells show highly invasive behavior in vitro, subcutaneous primary tumors grow solidly without detectable metastatic spreading. However, AS cells when applied to the syngeneic rats via the tail vein give rise to lung colonies which grow rapidly at the site of the cells' primary arrest in the capillaries. The colonization comprises formation of microemboli, penetration of the endothelium including the basal lamina, and invasion of the lung tissue. Within two weeks, large colonies develop, thereby compressing, invading, and destroying their surroundings without detectable preference in direction. This establishment of AS tumors in the lung reflects the high invasive potential of AS cells and displays many of the morphological features observed during the formation of colonies of metastatic cell lines. Thus, we conclude that a nonmetastatic tumor cell line, such as AS, may possess almost the whole set of properties necessary for successful metastasis.

Experimental approaches to problems of invasion and metastasis.

The highly metastasizing ASML cells and the non-metastasizing AS cells, arisen as spontaneous tumors of the rat, were confronted with rat lung tissue in vitro. Small cubes of the lung were allowed to heal their cut edges, then tumor cells were added. Both tumor cell types adapted their shape to the environment, penetrated the superficial layer of lung cells, either of epithelial or of fibroblastoid character and settled on the basal lamina, which, however, was not pierced. In a second set of experiments the tumor cells were inoculated intravenously into the living animal. The lung loaded with tumor cells was excised and cut into cubes which were then incubated in vitro. Here also both tumor cell types exhibited an invasive behavior but the basal lamina of the vessels in which the tumor cells have been arrested was not penetrated. These data indicate that tumor cell behavior is strongly dependent on the environment and the complete invasion or extravasation must be considered as an inducible process.

Invasive activities of metastasizing and nonmetastasizing tumor cell variants in vitro. II. Studies on confrontations with aorta, vein, ductus thoracicus, diaphragm, and lung.

In continuation of a previous paper (1), we have prolonged the time of confrontation of two rat tumor cell variants (BSp73 AS and ASML) with normal epithelial cells and broadened the spectrum of confrontation partners. In addition to the aorta we have also used small veins, the ductus thoracicus as a lymphatic vessel, the diaphragm, and lung fragments. The organ sections were preserved for a longer period of time by incubating them in a gyratory shaker. Under these conditions the vessel material and diaphragm remained morphologically intact for up to 12 hrs; lung cubes concealed the cut surfaces by immediate wound healing, and were preserved intact for up to 40 days. All endothelia and the mesothelium of the diaphragm were destroyed by the nonmetastasizing AS cells, but the basal lamina remained intact by morphological criteria even after 18 hrs of exposure to the AS cells. The metastasizing ASML cells attached by filopodia mostly to the basal lamina of the vessels, but were unable to destroy neither the endothelia nor the basal lamina. The superficial cell layers of the lung cubes, however, were penetrated by the cells of both tumor lines, but to a different degree.

Ultrastructural analysis of experimentally induced invasion in the rat lung by tumor cells metastasizing lymphatically.

The colonization of the lung by the rat tumor cells BSp73 ASML which have the ability to metastasize via the lymphatic system was studied at the ultrastructural level. Tumor cells arriving in the lung after i.v. injection become transiently embolized; within hours, however, they begin to extravasate from the blood capillaries. Swelling cellular protrusions open a limited area between endothelium and basal lamina through which tumor cells erupt. Tumor cells then form metastases in the interstitial tissue and, in an apparently lymphotropic action, intravasate the lymphatic vessels in a similar manner to a reverse diapedesis-like process. Within the lympatic system they settle, spread, and build up extensive tumor foci particularly in the subpleural region.

Effect of Avemar and Avemar + vitamin C on tumor growth and metastasis in experimental animals.

Because of the observed immunostimulatory actions of a new fermented wheat germ extract--with standardized benzoquinone composition--we have investigated the eventual tumor growth- and metastasis-inhibiting effects of this preparation (Avemar) applied alone or in combination with vitamin C. Tumor models of different origin [a highly metastatic variant of the Lewis lung carcinoma (3LL-HH), B16 melanoma, a rat nephroblastoma (RWT-M) and a human colon carcinoma xenograft (HCR25)]--kept in artificially immunosuppressed mice were applied. The metastasis-inhibiting effects of the treatments have been studied both in the presence and in the absence (following surgical removal) of the transplanted primary tumors. Combined treatments with Avemar and vitamin C--administered synchronously--profoundly inhibited the metastasis formation in all the applied tumor models while, treatments with vitamin C alone did not exert such an inhibiting effect on the metastasizing process. The degree of the observed metastasis inhibition in certain models was significant, while in others--although it was meaningful--did not prove to be significant. It is noteworthy that treatment with Avemar alone in certain models exerted a more pronounced inhibiting effect on metastasis formation than the synchronous combined treatment with Avemar and vitamin C. Furthermore, if the time schedule of the combined treatment was changed (vitamin C--instead of being administered synchronously--was given one hour after the treatments with Avemar), the vitamin C rather decreased the metastasis inhibiting effect of Avemar. It should be mentioned however, that in the case of rat nephroblastoma, a different response was observed: while, in the case of synchronous combination significant inhibition of metastasis formation was observed, treatment with Avemar alone did not produce metastasis-inhibition. It is noteworthy that in this model the metastasis-inhibiting effect of the synchronous combination treatment proved to be even more pronounced if Avemar was administered in a 100 times smaller dose than its regularly applied dosage. Treatment with Avemar and vitamin C--administered in combination or separately--in the majority of experimental models (with the exception of rat nephroblastoma) did not inhibit the growth of the primary tumors. It is reasonable, therefore, to suppose that in the observed metastasis-inhibiting effect the eventual proliferation inhibiting effect of these remedies does not play an important role. According to the results of other experiments--carried out in our laboratory in parallel with those described here--Avemar proved to have a meaningful immunostimulatory effect. It might therefore be suggested that the observed metastasis-inhibiting effect of this preparation may be mainly due to its immunostimulatory properties. The possible therapeutic benefits of Avemar and Avemar plus vitamin C are also discussed.

Antiproliferative efficacy of the somatostatin analogue TT-232 in human melanoma cells and tumours.

BACKGROUND: TT-232, a somatostatin analogue, induces apoptosis in various tumours. The aim of our study was to characterise its effect on human melanoma cells and tumours. MATERIALS AND METHODS: Proliferation of seven melanoma cell lines was tested in vitro with the methylene blue test. D10 and 205 cells were also implanted into CB17-scid mice which received 30-150-750 micrograms/kg/day of TT-232 or saline. Animals with 205 cells received twice-daily subcutaneous injections whereas animals with D10 cells were treated with osmotic mini-pumps. In addition, TT-232 metabolites were generated with tissue homogenates and tested in vitro. RESULTS: TT-232 strongly inhibited proliferation of all cell lines in vitro and tumour growth in vivo. Two out of 8 animals (30-150 micrograms/kg) in the 205 model and one out of 8(150 micrograms/kg) in the D10 model became completely tumour-free at the 11th and 9th day of treatment, respectively. TT-232 was degraded only by liver homogenate whilst its metabolite had no antiproliferative effect in vitro. CONCLUSIONS: TT-232 is a promising drug candidate for melanoma.

Current concepts of tumor-induced angiogenesis.

Tumor induced angiogenesis is responsible for the nutrition of the growing tumor and can also increase the probability of hematogenous tumor dissemination. Data obtained from morphological analysis of tumor angiogenesis can contribute to the development of new anti-angiogenic therapies. Based on in vitro and in vivo observations several models of angiogenesis were introduced, explaining the mechanism of lumen formation and the timing of basement membrane depositon. (1) Lumen is formed either by cell body curving or by fusion of intracellular vacuoles of nonpolarized endothelial cells. New basement membrane is deposited after lumen formation. (2) Slit-like lumen is immediately formed by migrating polarized endothelial cells. Basement membrane is continuously deposited during endothelial cell migration, only cellular processes of the endothelial cell migrating on the tip of the growing capillary are free of deposited basement membrane material. (3) Development of transluminal bridges in larger vessels a process called intussusceptive growth leads to the division of the vessels. These models, however, describe angiogenesis in tissues rich in connective tissue. Different processes of angiogenesis take place in organs such as liver, lungs, adrenals, which are the most frequent sites of metastasis having high vessel density without sufficient space for capillary sprouting. In the case of liver metastases of Lewis lung carcinoma the proliferation of endothelial cells was elicited only by direct contact between tumor and endothelial cells, leading to the development of large convoluted vessels inside the metastases. These vessels were continuous with the sinusoidal system, suggesting that these metastases have dual blood supply. This observation, among others, is in contrast to the generally accepted view that liver tumors have arterial blood supply. The increasing number of data demonstrating the dual or venous blood supply of liver metastases should be taken into consideration in the therapy of liver metastasis.

Tumor cell motility and metastasis : Autocrine motility factor as an example of ecto/exoenzyme cytokines.

Cellular locomotion plays a critical role in such normal processes as embryonic development, tissue segregation, as well as the infiltration of fibroblasts and vascular cells during wound repair and the inflammatory responses of the adult immune system. During tumor invasion and metastasis the processes of cell migration achieve dire significance. Disruption of normal homeostatic mechanisms to benefit the survival of the individual tumor cell is a common theme discovered during the characterization of factors once thought to be tumor-specific. One such molecule, tumor cell autocrine motility factor, was so described and has only recently been identified as a normal protein involved in intracellular glycolysis as well as implicated as an extracellular effector of normal cell functions including survival of certain populations of neurons. This molecule represents a member of the newly emerging family of intracellular enzymes whose disparate functions as extracellular mediators of cellular responses defines a new class of ecto/exoenzymes which play a role in normal cellular processes and are inappropriately utilized by tumor cells to elicit new survival strategies.