Cell surfaces and cancer metastasis

Cell membrane fluid-mosaic structure and cancer metastasis

Cancer cells are surrounded by a fluid-mosaic membrane that provides a highly dynamic structural barrier with the microenvironment, communication filter and transport, receptor and enzyme platform. This structure forms because of the physical properties of its constituents, which can move laterally and selectively within the membrane plane and associate with similar or different constituents, forming specific, functional domains. Over the years, data have accumulated on the amounts, structures, and mobilities of membrane constituents after transformation and during progression and metastasis. More recent information has shown the importance of specialized membrane domains, such as lipid rafts, protein-lipid complexes, receptor complexes, invadopodia, and other cellular structures in the malignant process. In describing the macrostructure and dynamics of plasma membranes, membrane-associated cytoskeletal structures and extracellular matrix are also important, constraining the motion of membrane components and acting as traction points for cell motility. These associations may be altered in malignant cells, and probably also in surrounding normal cells, promoting invasion and metastatic colonization. In addition, components can be released from cells as secretory molecules, enzymes, receptors, large macromolecular complexes, membrane vesicles, and exosomes that can modify the microenvironment, provide specific cross-talk, and facilitate invasion, survival, and growth of malignant cells.

Tumor progression- and metastasis-associated proteins identified using a model of locally recurrent rat mammary adenocarcinomas

A recently established model for local breast cancer recurrence using the 13762NF rat mammary adenocarcinoma was used to evaluate biologic and biochemical properties related to clinical outcome for this class of tumors. Sublines isolated from local tumor regrowths following surgical resection differed from each other and from the 'parental' cell lines for multiple phenotypes, including metastatic propensity. Local recurrence- and primary tumor-derived sublines were examined by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), lectin binding to electrophoretically separated proteins, and lactoperoxidase-catalyzed cell surface iodination; and differential protein patterns were compared to tumor progression and metastatic potential. 2D-PAGE revealed several quantitatively different spots which correlated with lung colonization potential. In particular, quantities of an apparently unique, non-cell-surface protein, P50.9 (Mr approximately 50,900, pI approximately 7.3) correlated inversely with metastatic propensity, suggesting that it may be associated with, among other possibilities, the negative regulation of the metastatic phenotype. P50.9 was unrelated to four similarly sized metastasis-associated proteins--tumor autocrine motility factor; the rat analog of tumor suppressor, p53; rat cytokeratin 14 or procathepsin D--as determined by amino acid analysis. A major wheat germ agglutinin binding sialoglycoprotein, gp93 (Mr approximately 93,000), was present in smaller amounts as cells were passaged in vivo and re-established as in vitro cultures [MTF7 greater than 'primary' tumor-derived lines (sc1, sc3) much greater than local recurrence-derived lines (LR1, LR1a, LR3, LR4, LR5, LR6)]. Besides cell surface glycoprotein losses, two of six local recurrence-derived sublines expressed a wheat germ agglutinin-binding sialoglycoprotein, gp110 (Mr approximately 110,000), previously undetected on any of the other cell lines including the parental populations. gp110 was found in LR3 and LR6 which were relatively highly metastatic; however, correlation with metastatic potential failed because gp110 was not present on the metastatic parental cell line, MTF7. These results demonstrate specific quantitative and qualitative protein differences associated with the selection of locally recurrent mammary tumors.

Tumor cells in intraoperative pleural lavage. An indicator for the poor prognosis of bronchogenic carcinoma

Fifty-nine patients with bronchogenic carcinoma and 21 patients with nonneoplastic lung diseases underwent intraoperative pleural lavage with 300-ml physiologic saline before (Lavage I) and after resection (Lavage II). The presence of tumor cells in the lavage fluid was established cytologically in 29 patients with bronchogenic carcinoma. Twenty-seven had positive findings in Lavage I and 23 of these also in Lavage II. Two patients had positive findings in Lavage II only. All controls were negative. In all 40% of patients with Stage I bronchogenic carcinoma had positive lavage results. The cumulative two-year survival rate of this group is 40%, which differs significantly (P less than 0.01) from the 97% survival rate of the patients with the same tumor stage whose lavage findings were negative. Detection of tumor cells in pleural cavity washings before resection proves that tumor cells have spread into the pleural cavity. Cytologic examination of an intraoperative pleural lavage should be done when assessing the tumor stage.

Metastatic dissemination of 3LL variants after treatment with monoclonal antibody to a tumor-associated antigen

Two tumor lines derived from 3LL (Lewis lung carcinoma) endowed with different metastatic potential and stable for their metastatic phenotype during serial in vivo passages, have been analysed for growth and dissemination following treatment with a monoclonal antibody. We have used a recently developed MoAb 135-13C to a tumor-associated antigen of murine lung carcinoma having an apparent molecular weight of 180,000 (TSP-180). The metastatic dissemination of the 3LL variants before and after treatment with the MoAb has been correlated with the expression on the cell surface of the MHC antigens (Db, Kb) and of the TSP-180 protein. The results of this study indicate that cell with high TSP-180 protein expression and MHC antigen expression have the greatest metastatic potential. Administration of MoAb 135-13C to tumor-bearing mice or i.v. injection of cells preincubated with the MoAb 135-13C increase the dissemination capacity of the variant endowed with lower metastatic potential while inducing a reverse effect on the high metastatic one. Studies on the MHC expression demonstrate that MoAb 135-13C treatment induces changes in the Db and Kb expression at level of secondary neoplasms. The results are discussed in view of the importance of the use of the metastatic variants to study therapeutic effect of specific targeting agent.

Factors influencing the growth and metastatic behavior of tumors

The factors influencing the growth and metastatic behavior of experimental animal tumors are examined. 10(4) TA3Ha cells were injected intraperitoneally, intravenously, subcutaneously into the flank, and subcutaneously into the tail tissues of syngeneic strain A mice. The tumor takes from these injections were 50/50 (100%), 1/10 (10%), 10/10 (100%), and 7/12 (60%), respectively. The frequency of lung metastasis from these sites was 0, 100, 50, and 100%, respectively. At the time of host death, the flank and tail tumors were, respectively, 2.2 +/- 0.5 cm (geometric mean diameter) and 1.2 +/- 0.3 cm in the TA3Ha and 0.9 +/- 0.1 cm and 0.4 +/- 0.1 cm in the L1210 systems. TA3Ha tumors metastasized regularly to the lymph nodes but the L1210 tumors seldom metastasized to the lymph nodes. Tail implants of TA3Ha tumors behaved similarly in the athymic nude mice and strain A mice. TA3Ha cells inoculated into the Millipore chambers and maintained in mice for greater than 150 days were viable and able to form tumors. The results demonstrate that the anatomic location of the tumor affects the growth and metastatic behavior of the tumors, and that the tumors of different histologic origin metastasize differently even when grown in corresponding locations.

Basic mechanisms of metastasis

Metastatic disease is responsible for the majority of deaths caused by cancer. The process of metastasis is an orderly, stepwise process that results in the selection of cells that possess the capability to establish viable metastases. These cells must be locally invasive and be able to survive the physical traumas of dissemination and normal host defenses. Once metastatic cells have been arrested in a capillary bed, they must be able to invade the host organ parenchyma and survive in that milieu. Studies in a number of model systems have documented the phenotypic alterations in cells that have "metastatic potential." These differences may stem from normal tumor cell heterogeneity and surprisingly reflect only minor differences in gene expression. The role of activated oncogenes in metastasis is unclear, but a number of laboratories have documented that transfection with activated Ha-Ras results in increased metastatic potential. An increased understanding of the genetic basis of metastatic potential may suggest new directions for intervening in this deadly process.

Temperature elevation during brachytherapy for carcinoma of the uterine cervix: adverse effect on survival and enhancement of distant metastasis

Possible effects of fever during intracavitary radiation therapy on patient survival, local-regional control or metastatic spread of disease were analyzed in a group of 398 patients with previously untreated, invasive carcinoma of the uterine cervix, managed with a combination of external beam irradiation and intracavitary radium (ICR) applications at Yale-New Haven Medical Center and affiliated hospitals from January 1953 through December 1977. Cox step-wise proportional hazard models were used to test for the influence of elevated temperatures during ICR placements, controlling for the influence of other pretreatment patient parameters, including FIGO stage, age, blood count, prior supracervical hysterectomy and number of prior pregnancies. Increasing maximum temperatures noted during ICR placements were associated with: decreased patient survival (p = 0.014) and increased frequency with time of distant metastasis as the initial sites of treatment failure (p = 0.038). When patients were dichotomized on the basis of maximum temperature during ICR, distant metastasis as the initial site(s) of treatment failure was noted twice as frequently in patients with maximum temperatures greater than or equal to 101.0 degrees F (12.5%; 10/80 patients) than in those with maximum temperatures less than 101.0 degrees F during ICR placement (6.3%; 20/318 patients). No statistically significant differences were noted between the two groups in their distributions by stage, age, histology, year of diagnosis, or pretreatment hemoglobin, and the sites of distant metastasis and time course for clinical detection were similar in both groups. These results are in agreement with prior clinical studies in cancer of the uterine cervix which noted a poor prognosis in patients with cancer of cervix who developed fever during treatment. In addition, the finding of an association between an increased frequency of distant metastasis and temperature elevation during the ICR provides, for the first time, clinical data supporting the reports of an alteration or enhancement of distant metastasis following the application of whole body hyperthermia in murine, rabbit and canine tumors.

Chromosome analysis of two rat tumor cell lines. Possible role of DMs and HSR in metastasis

The rat tumor cell lines BSp73AS (AS, non-metastasizing with pronounced adherent capacities) and BSp73ASML (ASML, highly metastasizing with reduced adherent capacities) were cytogenetically investigated. The ASML cell line is reportedly derived from the AS cell line. Both lines exhibited abnormal numerical and structural chromosomal characteristics. The metastasizing ASML cells showed a higher chromosome number (modal number: 62-63) than the nonmetastasizing AS cells (modal number:48). The AS karyotype was characterized by the presence of a large metacentric marker chromosome resulting from a Robertsonian translocation (Rb 6.7). This chromosome is as such absent in ASML cells but perhaps it may be present in these cells with a major part of chromosome 7 being deleted. The most interesting feature of the ASML karyotype was the presence of double minutes (DMs) and a homogeneously staining region (HSR) at the telomeric end of chromosome 6. These were peculiar to the ASML cells, being absent in the AS cells. DMs and HSR are reported to be correlated with the resistance to various drugs and with the acquired virulence of tumor cells through gene amplification. Therefore, we assume that in the metastasizing ASML cell line the DMs and HSR were established through genetic selection and that they are probably related to the acquired metastasizing capacity of these cells.