Characterization of sialytransferase in noncancerous and neoplastic human liver tissue.

When compared to uninvolved adjacent tissue, metastatic tumors in human liver appear to have significantly reduced sialytransferase activity. No significant kinetic differences (Michaelis constants, thermostability, and pH optima) between noncancerous and cancerous tissue sialytransferase were found. Mixing experiments between cancerous and noncancerous tissues indicated that inhibitors of sialytransferase activity were present in cancerous tissue. Subsequent experiments demonstrated increased levels of bound sialic acid in the tumor tissues. Inasmuch as futuin, a sialoglycoprotein, inhibits sialyltransferase activity, the increased levels of bound sialic acid in tumor tissue may be responsible for the reduced enzyme activity in these tissues.

Control of melanogenesis in mouse melanoma cells of varying metastatic potential.

The control of melanin production, tyrosinase activity, and cell replication by melanocyte-stimulating hormone (MSH) and cyclic AMP (cAMP) was examined in differentially metastasizing B16 mouse melanoma variants. In B16-F1 cells (low metastatic potential), MSH or cAMP greatly elevated tyrosinase activity and melanin content while inhibiting cell replication. The same parameters in B16-F5 cells (intermediate metastatic potential) were altered to a much lesser degree, whereas B16-F10 cells (high metastatic potential) were not significantly affected by MSH or cAMP. Therefore, a correlation exists between loss of hormonal regulation and increased metastatic potential.

Altered glucose metabolism in metastatic carcinoma.

To evaluate the possible role of altered glucose metabolism in malignant cachexia, metabolic parameters including total glucose turnover, glucose oxidation, and Cori cycle activity were measured in fourteen patients with metastatic carcinoma. Eight patients with progressive weight loss (PWL) were compared to 6 without (controls). Cori cycle activity was significantly increased (p less than 0.02) in PWL patients, 90 mg/kg/hr (range, 22 to 193) compared to 18 mg/kg/hr (range, 13 to 24) in controls. Total glucose turnover was moderately increased in PWL patients, 196 mg/kg/hr compared to 110 mg/kg/hr in controls. Glucose oxidation was 62 mg/kg/hr versus 48 mg/kg/hr, and total caloric expenditure was 36 kcal/sq m/hr compared to 33 Kcal/sq m/hr. PWL patients were metabolically heterogenous and mean values are skewed by four patients with increased glucose turnover, oxidation, and markedly high recycling rates that were equivalent to total endogenous glucose turnover of a normal subject. Total caloric expenditure was greatest in three of the four patients with a marked increase in Cori cycle activity. Energy loss associated with a high rate of gluconeogenesis from lactate has been suggested as an explanation for increased energy expenditure in some cancer patients, thus contributing to mechanisms that promote weight loss.

Differential production of high molecular weight sulfated glycoproteins in normal colonic mucosa, primary colon carcinoma, and metastases.

Sulfated macromolecules synthesized in tumor and mucosa tissues derived from colorectal cancer patients were labeled with [35S]sulfate and separated into two fractions on DEAE-Sephacel: the slightly acidic peak (peak I) was eluted with 0.2 M NaCl and the highly acidic peak (peak II) was eluted with 0.5 M NaCl. A total of 40 specimens, which included primary colon cancer, liver metastases, and normal mucosa obtained at surgery (16 patients), were examined regarding the amount of peak I and peak II. The amount of peak I significantly decreased in the order of normal mucosa greater than primary tumors greater than metastases, while the amount of peak II did not significantly change among the tissues. Peak I was mostly resistant to chondroitinase ABC and nitrous acid treatment under acidic conditions, whereas combined chondroitinase-sensitive materials and nitrous acid-sensitive materials were greater than 80% of the radioactivity in peak II. The major radioactive component of peak I migrated at a position corresponding to Mr greater than 300,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and became Mr less than 40,000 after alkaline borohydride treatment. The major component of peak I was likely to be a sulfated glycoprotein containing sulfate groups on alkaline labile carbohydrate chains. Peak II consisted of a mixture of heparan sulfate proteoglycans and chondroitin sulfate proteoglycans. Differential incorporation of [35S]sulfate into peak I among normal mucosa, primary colon carcinoma, and colon carcinoma metastasis was observed. Therefore, decreased peak I production may be a biochemical change associated with colorectal cancer progression and metastasis.

Linoleic acid metabolism in metastatic and nonmetastatic murine mammary tumor cells.

The mechanism(s) by which dietary linoleic acid (18:2n-6) enhances mammary tumor growth and metastasis is not known. Since arachidonic acid (20:4n-6)-derived prostaglandins (PG) may play a role in the metastatic dissemination of tumor cells, the ability of two murine mammary tumor cell lines, 4526 (metastasis positive) and line 168 (spontaneous metastasis negative), to convert 18:2n-6 into prostaglandins was examined. Cells were initially incubated with [14C]18:2n-6 and after 8-24 h the [14C]fatty acids were quantitated by high-performance liquid chromatography following transesterification. [14C]18:2n-6 was metabolized primarily to [14C]dihomogammalinolenic acid (20:3n-6) in line 4526 cells and [14C]20:4n-6 in line 168 cells. Examination of cellular fatty acid levels revealed a 20:3n-6/20:4n-6 ratio of 1.79 +/- 0.36 and 0.20 +/- 0.02 in line 4526 and 168 cells, respectively. These data are consistent with an inherently lower delta 5 desaturase activity in line 4526 relative to 168. To assess the metabolism of 18:2n-6 into eicosanoid products, the cell lines were prelabeled with [14C]18:2n-6 or 0-40 microM nonradiolabeled 18:2n-6 overnight and subsequently stimulated with calcium ionophore A23187 for 1 h. Total PGE production, as determined by radioimmunoassay, was greater in 168 relative to 4526 cells at all 18:2n-6 concentrations. 14C-prostaglandins detected by high-performance liquid chromatography and argentation thin-layer chromatography were: PGF1 alpha and PGE1 (derived from 20:3n-6) and PGF2 alpha and PGE 2 (derived from 20:4n-6) from line 4526; PGE1 and PGE2 from line 168. PGE1/PGE2 ratios were 1.43 +/- 0.07 and 0.23 +/- 0.03 for 4526 and 168 lines, respectively. Neither cell line synthesized lipoxygenase products following [14C]18:2n-6 or [3H]-20:4n-6 incubations under the conditions employed. Additional studies are warranted in order to define the biological properties of 1- and 2-series cyclooxygenase products as they relate to tumor cell metastasis.

In vivo monitoring of the death rate of artificial murine pulmonary micrometastases.

A system is described for direct monitoring of the death rate of artificial murine pulmonary microscopic metastases in vivo. Metastatic fibrosarcoma cells or benign connective tissue cells labeled with [125I]iododeoxyuridine were injected i.v. Comparison of the long-term radioactive decay rate of these two cell types in the lung permitted identification of the portion of the decay curve reflecting the initial period of micrometastasis development and growth. About 5% of the injected tumor cells were retained in the lung in micrometastasis, and their average death rate could be monitored by loss of radioactivity from the lung. Systemic methotrexate (75.0 mg/kg) was administered as a single dose 80 hr after injection of tumor cells at a time when micrometastases had not yet become vascularized. This treatment killed about 60% of the micrometases and suppressed the appearance of gross metastases at 14 days.

Malignant cell glycoproteins and glycolipids.

The cell surface is involved in cell growth and division, cell-cell interaction, communication, differentiation and migration, and other processes likely to be involved in malignant transformation and/or the metastatic spread of cancer. Although there are many alterations of glycoproteins and glycolipids on the malignant cell surface, it is unclear whether these alterations are epiphenomena or an integral part of the malignancy process. This article reviews the recent literature and some earlier studies relevant for understanding emerging concepts and trends with respect to malignant cell glycoconjugates. Emphasis is on structural alterations of the carbohydrate portions of malignant cell glycoproteins and glycolipids and on the enzymes (glycosyltransferases and glycosidases) involved in their metabolism. Practical applications derived from malignant cell glycoconjugate studies are discussed briefly with respect to the diagnosis, staging, monitoring, and treatment of malignant disease. The review concludes by indicating which research areas on malignant cell glycoconjugates are likely to be fruitful in increasing our basic understanding of, and ability to deal effectively with, malignant disease.

Vitamin B6 deficiency in cancer patients.

The plasma pyridoxal phosphate concentration was determined in 30 cases of early breast cancer, 21 patients with locally recurrent disease, and 43 patients with systemic metastases. The two groups of advanced breast cancer had significantly lower plasma pyridoxal phosphate levels than 36 healthy women of similar age. Urinary 4-pyridoxic acid excretion was normal in breast cancer. Plasma pyridoxal phosphate concentrations were also reduced in 34 women with widespread cancer derived from primary sites other than breast, but were normal in 39 with early disease.

Microcytic normochromic anemia associated with iron storage by hypernephroma.

A renal-cell carcinoma was discovered and resected in a 38-year-old female patient who had microcytic normochromic anemia. During treatment with ferrous gluconate, the anemia regressed temporarily but reappeared with the onset of metastases to the abdominal lymph nodes. Heavy deposits of hemosiderin were observed in tumor cells in the resected kidney and lymph nodal metastases. It is postulated that the anemia resulted from metabolic diversion and storage of iron by the tumor cells.

Neoplastic progression evidenced in the L929 cell system. II. In vitro growth properties and biochemical characteristics of cell variants with different malignant behavior.

Using a culture cell system, derived from a low-tumorigenic strain of L929 mouse fibroblasts, including cell variants with different malignant behavior in vivo, we have tried to dissociate a group of biological and biochemical transformation-associated properties with respect to the process of neoplastic progression. It is shown that morphologic changes, nonalignment in vitro, and growth in soft-agar are not sufficient alterations for in vivo malignant behavior and, also, not useful indicators for further neoplastic progression. The rate of hexose uptake should also be considered as unrelated to this process. The increase in tumorigenicity, but without the concomitant development of metastasis ability of the cells, was associated with the decrease of a 160k cell surface protein and the diminution of the tumor dose 50%. Finally, further alteration in morphology and the appearance of a 177k cell surface protein were associated with the development of metastasis ability, in an early stage; loss of fibronectin and the ability to grow as macrocolonies in increasing concentrations of deoxyglucose appeared as associated to more advanced stages of neoplastic progression. On the whole, the approach of taking the in vivo behavior, and not the in vitro properties, as end-point for the study of transformation is recommended on the basis of this and a previous paper.

Dynamics of cancer cell interactions with microvasculature and interstitium.

Interactions of cancer cells with the microvasculature and the interstitium of non-malignant tissue were studied in a rabbit ear chamber preparation using intravital fluorescent microscopy. Injection of VX2 carcinoma cells into the auricular artery feeding the chamber led to mechanical entrapment, adhesion, and in some instances, extravasation of cancer cells. Implantation of VX2 cells in the interstitial space led to increases in the interstitial diffusion coefficients and the microvascular permeability. Our results are compared with those available in literature and directions for future research are pointed out.