Modulation of tumor cell response to chemotherapy by the organ environment

The outcome of cancer metastasis depends on the interaction of metastatic cells with various host factors. The implantation of human cancer cells into anatomically correct (orthotopic) sites in nude mice can be used to ascertain their metastatic potential. While it is clear that vascularity and local immunity can retard or facilitate tumor growth, we have found that the organ environment also influences tumor cell functions such as production of degradative enzymes. The organ microenvironment can also influence the response of metastases to chemotherapy. It is not uncommon to observe the regression of cancer metastases in one organ and their continued growth in other sites after systemic chemotherapy. We demonstrated this effect in a series of experiments using a murine fibrosarcoma, a murine colon carcinoma, and a human colon carcinoma. The tumor cells were implanted subcutaneously or into different visceral organs. Subcutaneous tumors were sensitive to doxorubicin (DXR), whereas lung or liver metastases were not. In contrast, sensitivity to 5-FU did not differ between these sites of growth. The differences in response to DXR between s.c. tumors (sensitive) and lung or liver tumors (resistant) were not due to variations in DXR potency or DXR distribution. The expression of the multidrug resistance-associated P-glycoprotein as determined by flow cytometric analysis of tumor cells harvested from lesions in different organs correlated inversely with their sensitivity to DXR: increased P-glycoprotein was associated with overexpression of mdr1 mRNA. However, the organ-specific mechanism for upregulating mdr1 and P-glycoprotein has yet to be elucidated.

Circumvention of multidrug-resistance in murine fibrosarcoma and colon-carcinoma cells by treatment with the alpha-adrenoceptor antagonist furobenzazepine

The purpose of this study was to determine whether agonists and antagonists of alpha-adrenoceptors that affect calcium fluxes and protein kinase C signal transduction alter the chemosensitivity of cancer cells that exhibit multidrug resistance (MDR). The effects of nine alpha-adrenoceptor antagonists or antagonists on the in vitro chemosensitivity of the UV-2237 murine fibrosarcoma and its doxorubicin-selected MDR variants (UV-2237-R1 and UV-2237-R10) were examined. Noncytotoxic concentrations of the alpha-adrenoceptor antagonist furobenzazepine enhanced the antitumor activity of doxorubicin, actinomycin D, vinblastine and vincristine, but not 5-fluorouracil. Similar effects of furobenzazepine were also observed in recently established doxorubicin-resistant MDR variants of the CT-26 murine colon carcinoma. The chemosensitizing effect of furobenzazepine was associated with an increase in intracellular accumulation of anticancer drugs. Furobenzazepine did not compete with [H-3]azidopine for photoaffinity labeling of P-glycoprotein, but it did produce a transient 30% reduction of P-glycoprotein in the MDR cells. These data indicate that furobenzazepine can reverse a P-glycoprotein-mediated experimental MDR phenotype.

Reversal of multidrug resistance in murine fibrosarcoma cells by thioxanthene flupentixol

The purpose of this study was to identify calcium channel and calmodulin antagonists effective in increasing the cytotoxic effects of several chemotherapeutic drugs against UV-2237 murine fibrosarcoma MDR cells. Among 8 compounds tested at nontoxic concentrations, flupentixol, a piperazine-substituted thioxanthene, was the most potent in enhancing the cytotoxicity of anticancer drugs commonly associated with the multidrug resistant (MDR) phenotype, such as Adriamycin, actinomycin D, vinblastine, and vincristine, but not 5-fluorouracil, a drug usually unaffected by MDR. The chemosensitizing effects of flupentixol were produced by increasing intracellular drug accumulation via a mechanism unrelated to the binding of the plasma membrane P-glycoprotein.

Calmodulin-cardiac troponin C chimeras. Effects of domain exchange on calcium binding and enzyme activation

Calmodulin (CaM) and the cardiac isoform of troponin C (cTnC) are close structural homologs, but cTnC cannot activate most CaM target enzymes. To investigate structure-function relationships, we constructed a series of CaM.cTnC chimeras and determined their ability to bind Ca2+ and activate CaM target enzymes. Previously, we exchanged domain 1 and found that the chimeras exhibited profoundly impaired activation of smooth muscle myosin light chain kinase (smMLCK) and had differential effects on other CaM target enzymes (George, S. E., VanBerkum, M. F. A., Ono, T., Cook, R., Hanley, R. M., Putkey, J. A., and Means, A. R. (1990) J. Biol. Chem. 265, 9228-9235). One of the domain 1 chimeras was a potent competitive inhibitor of smMLCK. We now extend our study of CaM.cTnC chimeras by exchanging all of the remaining functional domains of CaM and cTnC. We determined the ability of the chimeras to bind Ca2+ and activate phosphodiesterase (PDE) and smMLCK. Chimeras containing both domains 3 and 4 of cTnC exhibited high affinity Ca2+ binding that was indistinguishable from cTnC, whereas chimeras containing either domain 3 or 4 of cTnC demonstrated Ca2+ affinity that was intermediate between CaM and cTnC. All of the CaM.cTnC chimeras showed near-maximal PDE activation but required 5-775-fold higher concentrations than CaM to produce half-maximal PDE activation. In contrast, all of the chimeras showed impaired ability to activate smMLCK, and some were potent competitive inhibitors of smMLCK activation by CaM.

Cytotoxic T cells isolated from ovarian malignant ascites recognize a peptide derived from the HER-2/neu proto-oncogene

The HER-2/neu proto-oncogene encodes a transmembrane receptor protein whose expression is enhanced in a number of breast and ovarian tumors and correlates with tumor aggressiveness, suggesting that it may play an important role in tumor growth. Recent evidence suggests that HER-2/neu may be a potential candidate for targeted immune intervention. In this report we show that cytotoxic T lymphocytes (CTL) expanded from tumor-associated lymphocytes with HLA-A2+ and HER-2/neu+ tumors can specifically recognize synthetic peptides corresponding to amino acids 971-980 of HER-2/neu protein. This sequence includes a potential amphiphilic area containing both Rothbard's epitode motifs and HLA-A2 anchor residues. Our study provides the first direct evidence of HER-2/neu-reactive CTL in humans. The fact that these HER-2/neu peptide-reactive CTL show significantly lower reactivity with corresponding EGF-R peptides offers new perspectives for understanding the recognition of self-antigens by tumor-reactive T cells.

Adoptive immunotherapy of advanced renal cell cancer using PHA-stimulated autologous lymphocytes

Patients with advanced renal cell carcinoma, previously failed maximal treatment with standard chemo-hormonal-radiation therapies, were treated with plant lectin phytohemagglutinin (PHA)-stimulated autologous peripheral blood lymphocytes in a 10-year study with a 16-year follow up period. In a phase I-II setting, 52 patients were given subcutaneously 40-80 x 10(6) PHA-stimulated lymphocytes weekly for 3 weeks and then escalated to a maximum number of 80 x 10(9) lymphocytes over the next 9 weeks at 3 week intervals. In vitro blastogenesis under study conditions (10 micrograms/ml PHA for 72 hr) measured by [3H]thymidine uptake was optimal with lymphocyte stimulating indexes approaching 300. Lymphocytes obtained from patients with breast cancer, melanoma and renal cell carcinoma responded to PHA similarly to those from normal volunteers. All patients that responded developed erythematous reactions at the sites of injection; malaise, joint paint and chill-fever for 24-48 hr. The patients that responded the best were those with at least 1 positive reaction out of 4 skin tests (tuberculosis, yeast, dermatophytin, mumps) prior to therapy. All toxicity was transient and did not exceed Grade I based on criteria of the Southwest Oncology Group. The majority of patients developed a lymphopenia in the first 24 hr followed by a lymphocytosis 48-72 hr later. For some patients the lymphocytosis was as much as 30% atypical lymphocytes. Of 41 evaluable patients, there were 5 complete responses, 8 partial responses, 3 stable diseases, and 25 progressive disease. The overall response rate was 32% and the median survival was 2.8 years.(ABSTRACT TRUNCATED AT 250 WORDS)

A simultaneous study of Doppler-echo and catheterization in noninvasive assessment of the left ventricular dp/dt

To confirm the feasibility and accuracy of the method for the noninvasive measurement of the left ventricular dp/dt, 53 patients with mitral regurgitation underwent simultaneous determination of left ventricular dp/dt by continuous-wave Doppler echocardiography and cardiac catheterization. Doppler-determined left ventricular dp/dt is derived from the Doppler mitral regurgitant spectrum by dividing the magnitude of the left ventricular-atrial pressure gradient rise between 1 and 3 m/s of the mitral regurgitant velocity signal by the time taken for this change. Left ventricular dp/dt by Doppler ranged from 629 to 3494 mmHg/s (mean +/- SD, 1971 +/- 785 mmHg/s), and that by catheterization varied between 716 and 3650 mmHg/s (mean +/- SD, 1974 +/- 727 mmHg/s). There was a high correlation (r = 0.93, y = 0.862x + 274.77, SEE = 271 mmHg/s, p < 0.001) of left ventricular dp/dt between the two techniques. It is concluded that left ventricular dp/dt is one of the most commonly used parameters for the evaluation of left ventricular systolic function and that Doppler echocardiography provides a new, accurate and noninvasive method of evaluation.

Noninvasive evaluation of right ventricular and pulmonary artery systolic pressures in patients with ventricular septal defects: simultaneous study of Doppler and catheterization data

The method for evaluating right ventricular and pulmonary artery systolic pressures by subtracting the systolic pressure gradient across the ventricular septal defect from the cuff systolic blood pressure is documented. To confirm the reliability and accuracy of this method, simultaneous continuous wave Doppler echocardiography and left and right cardiac catheterization were performed in 66 patients with congenital ventricular septal defects. The comparisons between the Doppler-derived right ventricular or pulmonary artery systolic pressures and those measured by catheterization yielded an excellent correlation (r = 0.969, y = 1.035x - 3.627, SEE = 8.2 mm Hg, p < 0.001 and r = 0.972, y = 1.012x - 2.904, SEE = 7.6 mm Hg, p < 0.001), respectively. There was a close agreement between the Doppler-derived right ventricular or pulmonary artery systolic pressures and those measured by catheters, and the differences between the two measurements did not differ significantly from zero. It is concluded that Doppler echocardiography offers a reliable and accurate method for noninvasive assessment of right ventricular and pulmonary artery systolic pressures in patients with ventricular septal defects.

Chemosensitization of murine fibrosarcoma cells to drugs affected by the multidrug resistance phenotype by the antidepressant trazodone - an experimental-model for the reversal of intrinsic drug-resistance

A variety of resistance phenotypes to cytotoxic agents in bacteria, protozoa parasites and mammalian cells are mediated by evolutionarily conserved proteins of the mdr family. The finding that chloroquine resistance in the malarial parasite, Plasmodium falciparum, that is mediated by an mdr-1 gene product can be circumvented by tricyclic antidepressant drugs has stimulated the present study to assess whether this class of agents might also modulate the multidrug resistance (MDR) phenotype(s) in mammalian tumor cells. The possible chemosensitizing effects of nine antidepressant drugs have been tested against the UV-2237M murine fibrosarcoma line and its MDR variant. At nontoxic concentrations all nine antidepressants markedly enhanced the cytotoxicity of ADR against the parental cells but were much less effective against the MDR cells. The most active antidepressant, trazodone, also enhanced the cytotoxicities of vinblastine and vincristine, but not those of actinomycin D, mitomycin C, or 5-fluorouracil. The parental cells treated with trazodone exhibited an increased accumulation of intracellular ADR, but lacked detectable alterations in the expression and drug-binding activity of plasma membrane P-glycoprotein, and trazodone did not affect the activities of isolated protein kinase C and calmodulin. These data suggest that the antidepressant drug trazodone may be useful in the reversal of the intrinsic drug resistance of tumor cells that express low levels of P-glycoprotein.

Simultaneous measurement of left atrial pressure by Doppler echocardiography and catheterization

Simultaneous, continuous wave Doppler echocardiography, left ventricular systolic and mean pulmonary capillary wedge pressure measurements were performed during cardiac catheterization in 54 patients with mitral regurgitation. Doppler-derived left atrial pressure, which was calculated by subtracting mitral regurgitant gradient from brachial artery systolic pressure, correlated well with mean pulmonary capillary wedge pressure by catheter (r = 0.933, SEE = 2.9 mmHg, P < 0.001); a comparison between non-invasive and invasive systolic gradients across the mitral valve yielded a high correlation (r = 0.91, SEE = 6.0 mmHg, P < 0.001); and there was also a high correlation between brachial artery and left ventricular systolic pressures (r = 0.93, SEE = 4.9 mmHg, P < 0.01). It is concluded that Doppler echocardiography provides a reliable and accurate method for complete non-invasive assessment of left atrial pressure in patients with mitral regurgitation.

Pulmonary artery diastolic pressure: a simultaneous Doppler echocardiography and catheterization study

Pulmonary hypertension is an important determinant of the clinical presentation of and surgical approach to patients with heart disease. To confirm the utility of continuous wave Doppler echocardiography in assessing the pulmonary artery diastolic pressure in patients with pulmonary regurgitation, 51 patients representing the wide hemodynamic spectrum of pulmonary artery pressure underwent simultaneous determination of pulmonary artery diastolic pressure by continuous wave Doppler echocardiography and cardiac catheterization. Pulmonary artery diastolic pressure was estimated from the Doppler recordings by the end-diastolic pressure gradient obtained by the modified Bernoulli equation plus the estimated right atrial pressure. A correlation was observed (r = 0.935, SEE = 7.4 mmHg) between Doppler and catheterization pulmonary artery diastolic pressure. In addition, comparison between the mean diastolic pressure gradient across the pulmonary valve by Doppler and pulmonary artery diastolic pressure at catheterization yielded a high correlation (r = 0.947, SEE = 5.1 mmHg). These data demonstrate that continuous wave Doppler echocardiography is a useful noninvasive technique for evaluating the pulmonary artery diastolic pressure in patients with pulmonary regurgitation.

Orthotopic and ectopic organ environments differentially influence the sensitivity of murine colon carcinoma cells to doxorubicin and 5-fluorouracil

We determined the effects of organ environment on the response of murine CT-26 colon carcinoma cells to 2 structurally and pharmacologically distinct chemotherapeutic agents. CT-26 cells were injected i.v. (to produce lung lesions), s.c., into the cecal wall, and into the spleen (to produce spleen and liver lesions). Doxorubicin (DXR) at 10 mg/kg, 5-fluorouracil (5-FU) at 20 mg/kg, or saline (control) was injected intravenously on different schedules after tumor-cell implantation. The in vivo responses of the tumors growing in the cecum, spleen, liver, lung and subcutis were compared. Colon carcinomas growing in the subcutis were most sensitive to DXR. Tumors growing in the spleen and cecum were most sensitive to 5-FU and less so to DXR. Tumors in the liver were highly resistant to both drugs, whereas experimental lung metastases were sensitive to 5-FU but resistant to DXR. The differential responses of the tumors to the drugs were not due to drug distribution. The level of protein-kinase-C activity was elevated in the spleen, liver and cecum tumors as compared with s.c. tumors and correlated with the in vivo DXR resistance of the tumor cells. This correlation suggested that organ environment may modulate the chemosensitivity of tumor cells, at least in part, by perturbing signal transduction pathways. Collectively, the data indicate that the organ environment has profound effects on the response of tumor cells to chemotherapy. A molecular understanding of this phenomenon should facilitate the design of more effective systemic chemotherapy for cancer metastases.

Noninvasive evaluation of interventricular pressure gradient across ventricular septal defect: a simultaneous study of Doppler echocardiography and cardiac catheterization

Simultaneous continuous-wave Doppler echocardiography and left- and right-sided cardiac pressure measurements were performed during cardiac catheterization in 64 patients with a congenital ventricular septal defect (VSD). The peak-to-peak pressure gradient across the VSD on cardiac catheterization ranged from 0 to 109 mm Hg (61 +/- 31.7 mm Hg). The peak shunt velocity and peak pressure gradient across the VSD on Doppler ultrasound imaging ranged from 0.96 to 5.21 m/sec (3.75 +/- 1.16 m/sec) and from 4 to 105 mm Hg (62 +/- 29.8 mm Hg), respectively. Doppler measurements of the peak interventricular pressure gradient correlated well with measurements obtained by cardiac catheterization (r = 0.98, standard error of estimate = 6.3 mm Hg, p less than 0.001). Doppler ultrasound imaging yielded information comparable to that obtained by catheterization and provided an accurate method of measuring the pressure gradient across the VSD, which is a useful parameter for the assessment of pulmonary artery systolic pressure in patients with a VSD, without a left or right ventricular outflow tract obstruction.

Stable expression of a cDNA encoding rat brain protein kinase C-beta I confers a multidrug-resistant phenotype on rat fibroblasts

Protein kinase C (PKC) is a Ca++- and phospholipid-dependent protein kinase that plays an important role in signal transduction pathways that regulate cell growth. Tumor cells selected for a multidrug resistant (MDR) phenotype often express elevated levels of PKC activity. To directly test whether PCK overexpression can produce an MDR phenotype, we studied rat embryo fibroblasts that were infected with the full-length cDNA clone RP58 encoding the beta I form of rat brain PKC. The PKC-beta I gene recipient R6-PKC3 cells are stable, overproduce PKC, and express an elevated level of PKC activity. R6-PKC3 cells exhibited significant resistance to adriamycin, actinomycin D, vinblastine, and vincristine but not to 5-fluorouracil. Intracellular accumulation of adriamycin, vinblastine, and vincristine was decreased in the R6-PKC3 cells, but this was not associated with an altered level of P-glycoprotein expression. Moreover, the reduction in drug accumulation appeared to be a consequence of a decreased rate of drug uptake. The data indicate that overexpression of PKC in rat fibroblasts produces an MDR phenotype without altering P-glycoprotein expression.

Takayasu arteritis in China: A report of 530 cases

A total of 530 patients with Takayasu arteritis were studied. Among 346 patients who were diagnosed by aortography, the female to male ratio was 2.9 to 1, and the age of onset ranged from 5 to 45 years. Three hundred and eighteen (60%) patients with secondary hypertension, including renovascular hypertension in 281, and 197 (37.2%) with pulseless extremities were found in the series. All the patients were treated with medical or surgical procedures. Surgical treatment is preferred if clinical status of the patient permits. The patients were followed for 1-29 years (average 7.8 years). There were 55 deaths (10.4%) in this series. Cerebral hemorrhage was found as a common cause of death. Five-year and ten-year survival rates were 93.1% and 91.1%, respectively.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) in the management of cancer

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is one of the four major colony-stimulating factors (CSFs) that regulate hematopoiesis. GM-CSF can stimulate a single bone marrow stem cell to proliferate and differentiate into mature neutrophils, eosinophils, granulocytes or macrophages. The outcome of recent clinical trials indicates that GM-CSF has the prospect of being clinically effective in augmenting the recovery of hematopoiesis in recipients of autologous bone marrow transplantation, in cancer patients suffering from the hematopoietic toxicity associated with chemotherapy and radiation therapy, and in patients with acquired immunodeficiency syndrome (AIDS).

Inhibition of murine melanoma experimental metastasis by recombinant desulfatohirudin, a highly specific thrombin inhibitor

Recombinant desulfatohirudin (r-hirudin), a highly specific inhibitor of thrombin, was examined to determine whether it would inhibit production of experimental lung metastasis by B16-F10 melanoma cells. In in vitro assays using mouse plasma, the high level of procoagulant activity in B16-F10 cells was significantly inhibited by r-hirudin in a dose-dependent manner. From 15 to 120 min after s.c. administration into C57BL/6 mice, r-hirudin (10 mg/kg) markedly prolonged clotting time in a time course pattern that directly correlated with that of blood distribution of 125I-labeled r-hirudin. The production of experimental lung metastasis by B16-F10 cells was significantly inhibited by r-hirudin administered s.c. at time points ranging from 120 min before to 60 min after tumor cell inoculation with the most significant effects found in mice given r-hirudin 15 or 2 min before the i.v. injection of tumor cells. The organ distribution of [125I]IdUrd-labeled tumor cells demonstrated a clear difference in the lungs of mice treated with r-hirudin and the lungs of control mice, and these differences directly correlated with the number of lung tumor colonies found 3 weeks later. The inhibition of lung metastasis was not due to direct antitumor effects of r-hirudin. These results suggest that inhibition of coagulation events by r-hirudin significantly inhibit experimental lung metastasis during a critical time of 60 min after the entry of tumor cells into the circulation.

Optimization of the liposomes encapsulating a new lipopeptide CGP 31362 for efficient activation of tumoricidal properties in monocytes and macrophages

The purpose of this study was to optimize a suitable liposomal carrier for CGP 31362, a new synthetic lipopeptide analogue of gram-negative bacterial cell walls. CGP 31362 was inserted into the membranes of different liposomes with different phospholipid composition. We determined the ability of these liposomes to activate tumoricidal properties in mouse peritoneal and bone marrow macrophages, and in human monocytes. The ideal liposome carrier for CGP 31362 consisted of phosphatidylcholine and phosphatidylserine in a 7:3 molar ratio. Subsequent to efficient binding and endocytosis, CGP 31362 in liposomes of this composition rendered mouse macrophages and human monocytes highly tumoricidal. Moreover, even in the absence of interferon-gamma, human monocytes released significant levels of tumor necrosis factor and interleukin-1. These data show that in a suitable liposomal carrier, the new synthetic lipopeptide in liposomes is a potent activator of tumoricidal properties in macrophages.

Lymphocytes infiltrating ovarian malignant ascites: modulation of IL-2-induced proliferation by IL-4 and of selective increase in CD8+ T cells by TNF-alpha

Lymphocytes infiltrating ovarian malignant ascites (TALs) were propagated in vitro in the presence of low (20-50 U/ml) concentrations of recombinant interleukin-2 (rIL-2) and moderate concentrations of interleukin-4 (IL-4) and tumor necrosis factor type alpha (TNF-alpha). Neither IL-4 nor TNF-alpha alone induced proliferation of ovarian TALs, but IL-4 and TNF-alpha synergized with IL-2 in enhancing the proliferation of T cells from cultures and inducing a more specific pattern of cytotoxic responses of ovarian TAL. IL-4 enhanced the proliferation of TAL cultures in the induction phase, but did not synergize with IL-2 in enhancing the proliferation and cytotoxicity of an established autologous tumor-specific CD8+/CD4- cytotoxic T lymphocyte (CTL) line. In contrast, TNF-alpha-induced preferential expansion of CD8+ CTL in TAL cultures where CD3+/CD4+ cells were initially in excess and of an established autologous tumor-specific CD8+ CTL line. This expansion resulted in increased levels of cytoxicity against autologous tumor cells. Amplification of IL-2 growth-promoting effects and selective enrichment in T cell subsets by IL-4 and TNF-alpha may therefore be useful in cellular adoptive immunotherapy using tumor-specific T cells.

Growth modulation by epidermal growth factor (EGF) in human colonic carcinoma cells: constitutive expression of the human EGF gene

The functional role of epidermal growth factor (EGF) in epithelium-derived human colonic carcinoma cells was investigated by transfection with plasmid pUCDS3, which contained synthetic human EGF encoding sequences, into two human colonic carcinoma cell types with dissimilar phenotypic properties: the moderately differentiated and growth factor-responsive Moser and the highly metastatic KM12SM cells. The Moser cells exhibited a proliferative response to treatment with exogenous EGF, while the KM12SM cells did not. The constitutive expression of the human EGF gene in these colonic carcinoma cell types resulted in elevated expression of EGF mRNA, with concurrent production and secretion of a large amount of EGF, and downmodulation of transforming growth factor-alpha (TGF-alpha) secretion. Growth stimulation and down-modulation of both high and low affinity EGF receptors were observed in the EGF-transfected Moser clones. Results of experiments using anti-EGF and anti-EGF-receptor antibody to block the proliferation of EGF-transfected Moser clones suggested that autocrine stimulatory mechanisms involving both EGF and TGF-alpha were operative in these cells. By comparison, a growth-inhibitory effect, with no apparent EGF receptor modulation, was observed in the EGF-transfected KM12SM clones. Both the parental and EGF-transfected KM12SM clones possessed fewer EGF receptors than the Moser cells, and anti-EGF or anti-EGF-receptor antibody did not affect the cells' growth properties. These results suggested that the mechanisms of growth inhibition in the EGF-transfected KM12SM clones were non-autocrine or intracellular in nature. Thus, constitutive expression of the human EGF gene in two phenotypically different, epithelium-derived human colonic carcinoma cells resulted in divergent altered growth characteristics.

A novel N-myristylated synthetic octapeptide inhibits protein kinase C activity and partially reverses murine fibrosarcoma cell resistance to adriamycin

This report shows that N-acylation of the protein kinase C (PKC) substrate Arg-Lys-Arg-Thr-Leu-Arg-Arg-Leu (RKRTLRRL) provides it with a potent inhibitory activity against PKC. N-myristoyl-RKRTLRRL inhibited Ca2(+)- and phosphatidylserine (PS)-dependent histone phosphorylation catalyzed by PKC with a 50% inhibitory concentration (IC50) of 5 microM, whereas neither RKRTLRRL nor myristic acid inhibited PKC-catalyzed histone phosphorylation at concentrations as high as 50 microM. A fully active, Ca2(+)- and PS-independent catalytic fragment of PKC can be generated by limited proteolysis. N-myristoyl-RKRTLRRL inhibited histone phosphorylation catalyzed by the catalytic fragment of PKC (IC50 = 80 microM), but neither myristic acid nor the nonmyristylated peptide inhibited the activity of the catalytic fragment at concentrations up to and including 200 microM. The Km app and Vmax app for N-myristoyl-RKRTLRRL were similar to those of RKRTLRRL. Thus, N-myristylation provided the octapeptide with an inhibitory activity against PKC but had only minor effects on its Km app and Vmax app. Kinetic analysis provided evidence that the peptide inhibited PKC noncompetitively with respect to ATP. Previously, we reported that the protein kinase inhibitor H7 partially reverses Adriamycin resistance in the multidrug resistant (MDR) murine fibrosarcoma line UV-2237M-ADRR. In this report, we show that N-myristoyl-RKRTLRRL also partially reverses Adriamycin resistance in UV-2237M-ADRR cells. These results suggest that potent and selective cell permeable PKC inhibitors may be designed by N-acylating small PKC peptide substrates.

In vitro model for intrinsic drug resistance: effects of protein kinase C activators on the chemosensitivity of cultured human colon cancer cells

We investigated the effects that phorbol ester and diacylglycerol protein kinase C (PKC) activators had on the chemosensitivity of the human colon cancer cell line KM12L4a to Adriamycin (ADR), vincristine (VCR), and vinblastine (VLB) and on the intracellular accumulation of those drugs. Exposure of the cells to the PKC activator phorbol-12,13-dibutyrate (PDBu) (15 nM) during a 96-hr in vitro chemosensitivity assay significantly reduced the sensitivity of KM12L4a cells to ADR, VCR, and VLB, but not to 5-fluorouracil. Because a 96-hr treatment with 15 nM PDBu did not down-regulate PKC activity in KM12L4a cells, activation of PKC appeared to be responsible for the observed protection conferred by PDBu. PDBu-induced alterations in drug accumulation may account for its protective effects against these cytotoxic drugs, because both PDBu and the phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate significantly reduced accumulation of [3H] VCR and [14C]ADR in the cultured human colon cancer cells. Unsaturated diacylglycerols are structural and functional analogues of phorbol ester PKC activators that are present in the lumen of the colon. We found that treatment of KM12L4a human colon cancer cells with the diacylglycerol 1-oleoyl-2-acetyl-sn-glycerol (OAG) significantly reduced [14C]ADR and [3H]VCR accumulation in the cells. The effects of OAG were dose dependent at physiological diacylglycerol concentrations and were completely reversed by the protein kinase inhibitor H7. OAG, which is rapidly metabolized in cultured cells, did not protect KM12L4a cells against the cytotoxic drugs in our 96-hr in vitro chemosensitivity assay. However, rapid metabolism of diacylglycerols should not limit their capacity to activate PKC in the colonic epithelium in vivo, because that tissue is chronically exposed to replenished supplies of unsaturated diacylglycerols in the intestinal tract. Our results provide evidence that unsaturated diacylglycerols may be environmental factors that contribute to the intrinsic drug resistance of colon cancer in vivo by reducing drug accumulation in the cancer cells.

Use of MG series monoclonal antibodies in the diagnosis and experimental targeting therapy of gastric cancer

In order to facilitate early diagnosis and improve the treatment of gastric cancer, 12 murine hybridoma cell lines capable of producing monoclonal antibodies (mAb) against gastric cancer were established. These monoclonal antibodies were used in histopathological diagnosis, cytological and serological diagnosis, and radioimmunoimaging (RII). Also, immunoconjugates and immunoliposomes were produced by linking these antibodies with various anticancer agents. In vitro and in vivo studies in mice were carried out to investigate the possible uses of these antibodies in experimental targeting therapy of gastric cancer. This paper presents a review of these studies.

Transient enhancement of multidrug resistance by the bile acid deoxycholate in murine fibrosarcoma cells in vitro

Recent studies have implicated protein kinase C (PKC) activation in drug resistance in vitro. PKC can be activated directly by phorbol-ester tumor promoters as well as by the bile acid deoxycholate. In this report, we demonstrate that deoxycholate, at concentrations that are chronically present in the lumen of the colon in vivo, mimicked phorbol-ester tumor promoters by protecting Adriamycin (ADR)-sensitive and multidrug-resistant (MDR) murine fibrosarcoma UV-2237M cells from ADR cytotoxicity. Deoxycholate also enhanced the resistance of the MDR cell line UV-2237M-ADRR to the cytotoxic effects of vincristine and vinblastine. In contrast to cytotoxic drug-selected MDR phenotypes, deoxycholate-induced drug resistance was transient and required continuous exposure to the bile acid. The protein kinase inhibitor H7 completely reversed the protection against ADR cytotoxicity conferred on UV-2237M-ADRR cells by deoxycholate, providing evidence that deoxycholate exerts its protective effects by a mechanism that involves stimulation of protein phosphorylation and not merely by detergent effects on membrane permeability. PKC consists of a family of at least seven isozymes with distinct modes of activation and substrate specificities. We previously reported that MDR UV-2237M cell lines contain higher levels of PKC activity than the parental ADR-sensitive UV-2237M cell line (O'Brian et al., FEBS Lett 246: 78-82, 1989). The present report shows that PKC-III is a major PKC isozyme in ADR-sensitive and MDR UV-2237M cell lines. Thus, the resistance to ADR induced by the phorbol esters in UV-2237M cell lines provides strong evidence that PKC-III activation confers protection against ADR on ADR-sensitive and MDR UV-2237M cell lines. Furthermore, since deoxycholate is an endogenous molecule in the colonic epithelium, our finding that physiological concentrations of deoxycholate can render cells more resistant to chemotherapeutic drugs in vitro may have implications for the biology and therapy of intestinal cancers.

Cytotoxic potential of liposomes containing tumor necrosis factor-alpha against sensitive and resistant target cells

The purpose of these studies was to determine whether recombinant tumor necrosis factor (TNF) incorporated into liposomes produced enhanced antitumor effects against TNF-sensitive and TNF-resistant target cells. The lipid composition of liposomes influenced their binding to and endocytosis by target cells. Liposomes consisting of phosphatidylcholine and phosphatidylserine (7:3 molar ratio) bound to L929 cells and A375 human melanoma cells, albeit to different degrees. Liposomes retained encapsulated TNF for up to 48 h of incubation. TNF in liposomes lysed the TNF-sensitive A375 melanoma and L929 cells at levels similar to that mediated by free, unencapsulated TNF. Cells selected for resistance against free TNF were not sensitive to TNF in liposomes. Since liposomes concentrate in organs with high levels of reticuloendothelial activity, and TNF in liposomes retains antitumor activity, this delivery system may prove to be useful for treatment of lymph node and hepatic metastases.

Overcoming murine tumor cell resistance to vinblastine by presentation of the drug in multilamellar liposomes consisting of phosphatidylcholine and phosphatidylserine

We determined whether vinblastine (VLB) encapsulated within multilamellar vesicle-liposomes (MLV) would reverse target cell resistance to the drug exhibited by the UV-2237M murine fibrosarcoma and its Adriamycin (ADR)-selected multidrug resistant (MDR) variants. Resistant fibrosarcoma cells were grown in medium containing 1 and 10 micrograms/ml ADR to yield the MDR lines UV-2237M/ADRR (ADR-1) and UV-2237M/ADRRR (ADR-10), respectively. VLB encapsulated in MLV composed of phosphatidylcholine (PC) and phosphatidylserine (PS) (7:3 molar ratio) was hydrophobic, occupied an internal space equivalent of 6.13 microliters/mumol, and was stable in medium at 37 degrees C for up to 6 days. The 50% inhibitory concentrations (IC50) of VLB were 2, 25, and 70 ng/ml for the parent, ADR-1, and ADR-10 cell lines, respectively. VLB in MLV significantly enhanced sensitivity of tumor cells to VLB. The respective IC50 of liposomal VLB were 0.5, 5.7, and 12 ng/ml for the parent, ADR-1, and ADR-10 lines. MLV containing saline were not toxic to the cells. These data indicate that presentation of VLB entrapped in PC:PS MLV provides a method to overcome tumor cell resistance to this drug.

Comparative efficacy of liposomes containing synthetic bacterial cell wall analogues for tumoricidal activation of monocytes and macrophages

We examined the activation to the tumoricidal state of normal mouse peritoneal exudate macrophages, bone marrow macrophages, and human blood monocytes by liposomes containing either lipophilic muramyl tripeptide (CGP 19,835) or a new synthetic analogue of lipoprotein from gram-negative bacteria outer wall, CGP 31,362, or combinations of the two. The superiority of liposomes containing the synthetic lipopeptide over liposomes containing lipophilic muramyl tripeptide for in vitro activation of monocytes and macrophages was demonstrated in several experiments. First, liposome-CGP-19,835 activated monocytes only in the presence of interferon-gamma, whereas activation with liposome-CGP 31,362 was interferon-independent. Second, activation of both mouse macrophages and human blood monocytes by liposome-CGP 31,362 occurred at a lower liposomal concentration than that by liposome-CGP 19,835. Third, monocytes incubated with liposome-CGP 31,362 released both tumor necrosis factor (TNF) and interleukin-1 activities, whereas monocytes treated with liposome-CGP 19,835 (in the absence of interferon-gamma) released only TNF activity. These data suggest that liposomes containing the synthetic lipopeptide CGP 31,362 are superior to liposomes containing CGP 19,835 for systemic activation of macrophages.

Site-dependent differences in response of the UV-2237 murine fibrosarcoma to systemic therapy with adriamycin

Murine fibrosarcoma UV-2237MM cells were implanted into different organs of syngeneic C3H/HeN mice. The resultant tumors were treated by i.v. administration of Adriamycin (ADR). Despite the high sensitivity of the fibrosarcoma cells to ADR in vitro, the established tumors growing in vivo exhibited marked differences in their responses to ADR. Tumors growing in the subcutis and the spleen were ADR-sensitive, whereas lung metastases were not. The resistance of lung metastases to ADR was not due to selection of a drug-resistant population since tumor cells isolated from lung metastases were highly sensitive to ADR under in vitro conditions. The responsiveness of skin and spleen tumors to ADR was due neither to increased blood supply nor to preferential accumulation of ADR, since both parameters were higher in lung metastases. Protein kinase C activity levels correlated with ADR resistance in the closely related murine fibrosarcoma cell line UV-2237 and its ADR-selected multidrug-resistant variants. However, nearly identical levels of protein kinase C activity were found in UV-2237MM tumors growing in the lung, spleen, and subcutis, indicating that protein kinase C activity levels did not account for the different responses to ADR. The present studies suggest that the organ environment influences the response of UV-2237MM to ADR administered systemically. This finding may have implications for the design of animal models for therapy of disseminated cancer.

Modulation of differentiation and proliferation in human colon carcinoma cells by transforming growth factor beta 1 and beta 2

We have previously characterized the diversity of cellular responses to transforming growth factor (TGF)-beta 1 from human colon carcinoma cells. We now show that morphological alteration and part of the growth-inhibitory responses elicited by growth factor (GF) are associated with the secondary effect of the induction of synthesis of extracellular matrix (ECM) glycoproteins. Specifically, morphological alteration is associated with the ECM glycoprotein laminin, and growth inhibition is associated with both laminin and fibronectin. Both TGF-beta 1 and TGF-beta 2 down-modulate the expression of nucleolar protein B23 (also known as numatrin or nucleophosmin, a positive regulator of cell proliferation). With one exception, the biological effects of both TGF-beta 1 and TGF-beta 2 on these human colon carcinoma cell lines are identical. Both GFs up-modulate the expression of carcinoembryonic antigen (CEA) and CEA-related gene products. However, some of these products are differentially regulated by TGF-beta 1 and TGF-beta 2. The differences in the profile of the induction of these CEA and CEA-related gene products, in the responsive cells, functionally distinguish TGF-beta 1 from TGF-beta 2. Finally, we identified and characterized some of the cellular proteins, the expression of which is up-modulated by GF. These proteins are epithelium-associated, differentiation-related cytokeratins. Both TGF-beta 1 and TGF-beta 2 up-modulate expression of the acidic and basic subtypes of human keratins in the responsive human colon carcinoma cells. Both the responsive and unresponsive cells, however, possess receptors for GFs.

Retention of vital dyes correlates inversely with the multidrug-resistant phenotype of adriamycin-selected murine fibrosarcoma variants

Retention of the vital dyes rhodamine 123 (R-123) and hydroethidine (HET) correlates inversely with the multidrug resistant phenotypes of the adriamycin (ADM)-selected variants of a uv-induced murine fibrosarcoma cell line (UV-2237M). The differential affinity of these dyes for specific cellular organelles makes them unique compounds for studies of cellular transport. HET enters viable cells freely, is dehydrogenated to ethidium bromide (EtBr), and is subsequently accumulated in the nucleus. Viable cells are impermeable to extracellular EtBr, facilitating kinetic analysis of the efflux of intracellular EtBr. We found that the metabolite EtBr was rapidly cleared by ADM-resistant but not by ADM-sensitive cells. R-123 has a high affinity to mitochondria. Our results show that ADM-sensitive cells retain R-123 whereas the ADM-resistant cells do not. The clearance of both R-123 and EtBr from these cells was inhibited by verapamil. Therefore, R-123 and HET may be considered MDR-associated compounds useful in studying the MDR phenotype of cancer cells. Previously we reported a direct correlation between the level of activity of the calcium- and phospholipid-dependent protein kinase (protein kinases C) and ADM resistance in UV-2237M variant lines. In this report, we demonstrate a direct correlation between cellular calcium and MDR in these cells. Although chelation of extracellular calcium by EDTA did not alter the fluorescence profile of R-123 of the various cell lines, treating the ADM-resistant variants with verapamil restored cellular calcium to the same level as that of the parental cells and, at the same time, retarded the facilitated efflux of R-123 and EtBr and partially reversed cancer cell resistance to ADM.

Enhancement of murine tumor cell sensitivity to adriamycin by presentation of the drug in phosphatidylcholine-phosphatidylserine liposomes

In vitro incubation of mouse UV-2237M fibrosarcoma cells with liposomes containing Adriamycin (ADR) produced significant cytotoxicity in drug-sensitive cells and in multidrug-resistant variants of this tumor. ADR was encapsulated in the aqueous space of multilamellar liposomes composed of phosphatidylcholine and phosphatidylserine. The preparation was stable in medium at 37 degrees C for up to 7 days. Free unencapsulated ADR produced cytostasis in parental ADR-sensitive cells but not in variant lines selected for resistance to the drug. In contrast, ADR encapsulated in multilamellar liposomes (MLV) produced high levels of cytostasis in both ADR-sensitive and ADR-resistant cells. The phospholipid composition of the MLV influenced the outcome of ADR-mediated cytostasis. ADR encapsulated in MLV consisting of only phosphatidylcholine did not produce cytostasis. Increasing the proportion of phosphatidylserine in the MLV increased the level of ADR-mediated cytotoxicity in cells resistant to free ADR. This effect was not due to simple modification of tumor cell surface by liposomes since ADR added to resistant cells together with liposomes containing buffer produced less cytostasis. The cytostasis of resistant cells by ADR in liposomes was not due to appreciable changes in the intracellular ADR concentration or localization within the cells because ADR-induced DNA cleavage was not found in ADR-resistant cells treated with cytostatic amounts of liposomal ADR. Whether the enhanced sensitivity of tumor cells to ADR was due to localized damage to the plasma membrane through a phosphatidylserine-mediated release of the drug to the cell surface is now under active investigation.

[Experimental study of healing process of anastomosis after "tunnel" esophagogastrostomy]

The "Tunnel" esophagogastrostromy has been clinically proven to be effective in reducing the postoperative anastomotic leakage. An experimental study was carried out in 28 dogs to compare the healing process of "Tunnel" esophagogastrostomy (group A) and end-to-side anastomosis (group B), aiming at finding out the mechanism of prevention of anastomotic leakage after "Tunnel" esophagogastrostomy. The results showed that the mucosa of the esophagus and the stomach had fused at the site of the anastomosis on the fifth day in group A and the same processes had completed on the seventh day in group B. The blood supply of "Tunnel" anastomosis is better than that of the conventional end-to-side anastomosis, hence the hastening of the healing process. The protecting barrier formed with the gastric seromuscular in the "Tunnel" anastomosis plays an important role in preventing the occurrence of postoperative anastomostic leakage.

The development of liposomes containing interferon alpha for the intravesical therapy of human superficial bladder cancer

Current therapy of human superficial bladder cancer includes the intravesical administration of antitumor drugs and immunomodulators. The purpose of these studies was to determine whether phospholipid liposomes that bind to human bladder cancer cells can improve the delivery of interferon alpha (IFN-alpha) to neoplastic urothelium. The antiproliferative activity of free IFN-alpha and IFN-alpha encapsulated in liposomes was assessed in vitro against the human transitional cell carcinoma line 253J. The cells were exposed to free and liposome-encapsulated IFN-alpha for short periods ranging from 30 minutes to four hours, and inhibition of cell growth was determined three days later. The production of greater than 25 percent cytostasis of 253J cells by free IFN-alpha required four hours of continuous exposure. In contrast, IFN-alpha encapsulated in liposomes produced 35 percent and 60 percent cytostasis after a 30-minute and four-hour exposure, respectively. Liposome-encapsulated IFN-alpha was also effective (50 percent cytostasis) against a subline of 253J cells selected for resistance against free IFN-alpha. Liposomes containing IFN-alpha were stable in the presence of human urine. In vivo studies in mice showed that intravesical administration of radiolabeled IFN-alpha or radiolabeled liposomes did not yield significant systemic absorption and deposition in distant organs. Collectively, these results suggest that the encapsulation of IFN-alpha within multilamellar liposomes may augment its antiproliferative activity, overcome some forms of tumor cell resistance to IFN-alpha, and prove useful for intravesical therapy of superficial bladder cancer.

Isolation of human colon carcinoma cells for resistance to a single interferon associated with cross-resistance to multiple recombinant interferons: alpha, beta, and gamma

We established variants resistant to human interferon (IFN) from an IFN-sensitive human colon carcinoma cell line and delineated some of the mechanisms for resistance to IFN-mediated cytotoxicity. The parent KM12C cells were incubated for 2 months in medium containing recombinant human IFN-alpha hybrid BBDD (r-IFN-alpha) or recombinant human IFN-gamma (r-IFN-gamma). Surviving variants were designated KM12 alpha R and KM12 gamma R, respectively. KM12 alpha R cells were cross-resistant to the cytostatic and cytolytic effects of r-IFN-alpha, r-IFN-beta, and r-IFN-gamma, whereas KM12 gamma R cells were resistant only to the effects of r-IFN-gamma. The parent and variant cell lines had similar in vitro growth rates and similar tumorigenicity in male BALB/c nude mice, but the mechanisms for resistance to IFNs differed in the two variant lines. The resistance of the cross-resistant KM12 alpha R cell line was not attributable to the loss of specific receptors, because our analyses demonstrated the presence of receptors for IFN-gamma, whereas the KM12 gamma R line lacked specific receptors for IFN-gamma. Northern blot analyses revealed that messenger RNA (mRNA) from the proto-oncogene c-myc was equally expressed in the IFN-sensitive and IFN-resistant cell lines and that treatment with r-IFN-gamma did not alter its expression. Treatment with r-IFN-gamma induced the expression of manganous superoxide dismutase mRNA in KM12C and KM12 alpha R cells, but not in KM12 gamma R cells, confirming that both KM12C and KM12 alpha R cells, but not KM12 gamma R cells, have functional receptors for IFN-gamma.

Carcinoembryonic antigen as a selective enhancer of colorectal cancer metastasis

Although the serum level of carcinoembryonic antigen (CEA) is directly associated with a poor prognosis in human colorectal carcinoma (CRC), its function is obscure. As a member of the immunoglobulin supergene family, CEA may be involved with intercellular recognition and binding and facilitate attachment of CRC to sites of metastasis. In an experimental metastasis model of CRC in athymic nude mice, a systemic injection of CEA enhanced experimental liver metastasis and implantation in liver by a weakly metastatic CRC. This CRC also selectively bound to CEA that was attached to plastic. Thus, CEA may function as an attachment factor for CRC.

[5-Fluorouracil in trabeculectomy: preliminary report]

Subconjunctival 5-FU injections were used as an adjunctive therapy in trabeculectomy for high risk glaucoma patients. We injected 5 mg once a day for five to seven days as a routine treatment. For the first 10 eyes, the injections were started immediately after the operation. However, for the remaining 9 eyes, the injections began 24 to 48 hours postoperative. If the appearance of the bleb was not prominent or enriched in vascularity, the duration of the injections should be extended to 10 to 14 days. At least 8 months of follow-up were available for 19 eyes, including aphakic glaucoma, 8 eyes; neovascular glaucoma, 2 eyes; previous failed filter, 6 eyes; total collapse of the anterior chamber with leucoma adherence, 1 eye; glaucoma due to mesodermal dysgenesis, 1 eye; and juvenile glaucoma, 1 eye (whose fellow eye had received twice failed filtering procedures). The results revealed a success rate of 79% (intraocular pressure below 22mmHg with or without topical medication). The success rate for aphakic glaucoma was 63% (5/8), for neovascular glaucoma 100% (2/2) and for the failed filters 83% (5/6). We also presume that 5-FU injections would be effective in the treatment of to abnormally marked fibrous proliferations caused by age factors. The complications related to the use of 5-FU include corneal epithelial defect 4/9 (21%), conjunctival leak 3/9 (16%), subconjunctival hematoma 1/19 (5%), and conjunctival sterile ulcer 1/19 (5%).

Augmentation of antiproliferative activity of interferon alfa against human bladder tumor cell lines by encapsulation of interferon alfa within liposomes

Present therapy for human bladder cancer includes the intravesical administration of antiproliferative agents, such as recombinant human interferon alfa (IFN-alpha). The administration of cytotoxic molecules encapsulated in liposomes could provide a more efficient method for such therapy. Therefore, we determined whether encapsulation of the recombinant human IFN-alpha hybrid BBDD within liposomes will produce antitumor effects against the human bladder cancer cell line 253J superior to those observed with free IFN-alpha. Adherent cells were cultured in medium alone, in medium containing different concentrations of IFN-alpha, or in medium containing multilamellar liposomes (phosphatidylcholine-phosphatidylserine at a molar ratio of 7:3) that encapsulated saline or IFN-alpha. Cell growth was determined 96-120 hours later. Additional control groups consisted of target cells cultured with free IFN-alpha or with IFN-alpha plus liposomes containing saline. Cytostasis mediated by free IFN-alpha alone or IFN-alpha in the presence of liposome-saline was identical and ranged from 0%-30% (10 IU/mL) to 45%-70% (1,000 IU/mL). Liposomes containing saline produced no effects. Liposome-encapsulated IFN-alpha produced significantly greater growth inhibition than free IFN-alpha: 40%-70% (10 IU/mL) and 80%-90% (1,000 IU/mL), respectively. Moreover, a 253J variant subline selected for resistance to free IFN-alpha was sensitive to IFN-alpha presented in liposomes. These data suggest that the encapsulation of antiproliferative agents such as IFN-alpha in liposomes can improve therapeutic results.

Correlation of growth capacity of human tumor cells in hard agarose with their in vivo proliferative capacity at specific metastatic sites

The purpose of this study was to determine whether the degree of anchorage-independent growth of human tumor cells in increasing concentrations of agarose correlated with the capacity of the cells to produce experimental metastases in nude mice. Human melanoma, breast carcinoma, and colon carcinoma cells from parental lines and variants selected in vivo for metastasis and in vitro cloned lines were plated into medium containing 0.3%, 0.6%, 0.9%, or 1.2% of agarose. These cells were also injected into nude mice: intravenously for melanoma, into the mammary fat pad for breast carcinoma, and into the spleen for colon carcinoma. Production of tumor cell colonies in dense agarose (greater than 0.6%) correlated with production of experimental metastases in the lung (melanoma, breast carcinoma) or liver (colon carcinoma). We conclude that the degree of anchorage-independent growth of tumor cells can predict their biological behavior and metastatic potential in vivo. Thus, this technique may be useful for the isolation of metastatic cells from heterogeneous human neoplasms.

Level of protein kinase C activity correlates directly with resistance to adriamycin in murine fibrosarcoma cells

In this report, we demonstrate a direct correlation between protein kinase C (PKC) activity and adriamycin (ADR) resistance in mouse fibrosarcoma cells. PKC activity was measured in four murine UV-2237M fibrosarcoma cell lines that differed in the degrees to which they expressed resistance to ADR, which is an inhibitor of PKC. A comparison of the four cell lines revealed a positive correlation between the level of PKC activity and resistance to ADR. Incubation of the cells with the PKC inhibitor H-7 produced a partial reversal of ADR resistance. Taken together, these results suggest a role for PKC in the mechanism of ADR resistance.

In vitro activity of bleomycin, tallysomycin S10b, and liblomycin against fresh human tumor cells

The objective of this study was to compare the relative in vitro cytotoxicity of bleomycin to that of two newer-generation analogues, tallysomycin S10b and liblomycin. The latter compound is of particular interest as it has recently been shown in preclinical studies to be free of a potential to cause pulmonary injury and yet to possess only a minor potential to produce myelotoxicity. Using the adhesive tumor cell culture system, we evaluated the activity of these three drugs against a panel of 13 human tumors of various types. The range of concentrations chosen was determined and normalized using a nonleukemic permanent mouse hematopoietic progenitor cell line. Those drug concentrations achieving 90% inhibition of growth (IC90) against the murine cell line were: 6.11 microM bleomycin; 7.53 microM tallysomycin S10b; and 0.6 microM liblomycin. When tested against fresh human tumors at equally myelotoxic IC90 concentrations, bleomycin and tallysomycin S10b (nonmyelotoxic compounds) both achieved 90% growth inhibition of all tumors, while liblomycin (a myelotoxic compound) produced an IC90 inhibition in 69% of all tumors. A comparison of drug IC90 values against individual fresh tumors indicated a correlation between bleomycin and its structurally related analogue tallysomycin S10b. No such correlation, however, was seen with liblomycin in comparison to either bleomycin or tallysomycin S10b. The relative activity of liblomycin versus that of bleomycin and tallysomycin S10b varied with individual tumors tested. The response rate of liblomycin, a myelotoxic compound within this normalized range, appears promising. These data represent the first comparison of liblomycin to bleomycin against a spectrum of fresh human tumors using a stem cell assay technique.

Mechanisms of combined effects of gamma-interferon and 5-fluorouracil on human colon cancers implanted into nude mice

The purpose of these studies was to determine the possible mechanisms responsible for the therapeutic effects of systemic administration of 5-fluorouracil (FUra) and gamma-interferon on disseminated human colon cancer. We used several human carcinoma cell lines that were established from different surgical specimens. Some lines were selected in nude mice for increased metastatic potential, and one line was selected in vitro for resistance to human recombinant gamma-interferon (r-IFN-gamma). In initial in vitro studies, FUra was cytostatic against all the human cell lines but did not produce cytolysis in any of the lines tested. The two r-IFN-gamma were species specific for both antitumor and immunomodulatory effects. Human r-IFN-gamma produced cytostatic and cytolytic effects against sensitive human colon carcinoma cells but did not activate tumoricidal properties in mouse macrophages. In contrast, mouse r-IFN-gamma had no direct cytotoxic effects against any of the human colon carcinoma lines but did activate tumoricidal properties in mouse macrophages. Human colon carcinoma cells (sensitive or resistant to human r-IFN-gamma) were implanted into the spleens of nude mice. Three days later, we began treatments with FUra and human or mouse r-IFN-gamma. In all experiments, the combination of FUra with mouse r-IFN-gamma produced the best therapeutic effects against growth of the cells in the spleen and in the liver. Because the mouse r-IFN-gamma is devoid of direct antitumor effects (against human tumor cells) but is a potent macrophage activator, these results suggest that the antitumor effects were due to direct antitumor effects of FUra and to activation of host defense mechanisms by the r-IFN-gamma.

Arrest and retention of multilamellar liposomes in the brain of normal mice or mice bearing experimental brain metastases

The blood-brain barrier presents a major obstacle to the systemic treatment of malignant brain tumors and brain metastases. We investigated whether the direct injection of liposomes into the internal carotid artery of normal mice or mice with experimental brain-melanoma metastases could allow delivery of anticancer drugs across this barrier. Liposomes of different sizes (greater than 5 microns, less than 1 micron, 40-80 nm) and lipid compositions were injected i.v. or into the internal carotid artery. The retention of liposomes in the brain of normal C3H/HeN mice was similar to that observed in mice with experimental brain cancer metastasis. The highest accumulation of liposomes in the brain occurred with large multilamellar vesicles, which also produced severe toxicity presumably due to embolism. Smaller liposomes were not toxic but did not accumulate in the brain. Liposomes injected i.v. did not accumulate in the brain, either. Thus, neither i.v. nor intracarotid administration of liposomes produce results suitable for therapy of brain tumors/metastases.

Antiproliferative activity of liposome-encapsulated transforming growth factor-beta against MDA-MB-435 human breast carcinoma cells

We determined whether transforming growth factor-beta (TGF-beta) could be encapsulated in phospholipid liposomes and then would mediate antiproliferative activity against the sensitive, human breast cancer cell line, MDA-MB-435. TGF-beta was encapsulated in multilamellar liposomes consisting of phosphatidylcholine (PC) or PC and phosphatidylserine (PS) at a 7:3 molar ratio. It was captured in both the aqueous phase and the bilayer lipid (hydrophilic and lipophilic association) and was stable for at least 24 hr of incubation at 37 degrees C in medium that contained 5% fetal bovine serum. In calcium- and magnesium-free Hanks' balanced salt solution, TGF-beta in the internal aqueous compartment was stable for at least five days, even in the presence of trypsin and ethylenediamine tetraacetic acid. TGF-beta (type 1 or 2) in liposomes was active as free-form TGF-beta in mediation of antiproliferative effects. The lipophilic nature of TGF-beta, which resulted in a high capture ratio in liposomes, coupled with exceptional stability, suggested that liposomes could be a carrier for the in vivo use of TGF-beta.

Clonal stimulation or inhibition of human colon carcinomas and human renal carcinomas mediated by transforming growth factor-beta 1

We examined various human carcinomas and cells populating a single human neoplasm to determine whether they exhibit a heterogeneous response to the effects of transforming growth factor-beta 1 (TGF-beta). Using recently established human colon carcinoma and renal cell carcinoma under defined in vitro conditions, we observed intertumoral and intratumoral heterogeneity and polarity of responses to TGF-beta (growth inhibition or stimulation) that did not correlate with the metastatic phenotype of the cancer cells as assessed in athymic nude mice. TGF-beta mediated both cytostatic and cytolytic effects against sensitive tumor cells, and these responses were not related to the effects of TGF-beta on the cell-cycle traverse. The human colon carcinoma and renal cell carcinoma, however, exhibited differences in the expression of TGF-beta receptors.

Antitumor activity against human tumor samples of cis-diamminedichloroplatinum(II) and analogues at equivalent in vitro myelotoxic concentrations

We compared the antitumor activity of cis-diamminedichloroplatinum(II) (cisplatin; CDDP) with three CDDP analogues: cis-diammine-1,1-cyclobutanedicarboxylateplatinum(II) (CBDCA), N-methyliminodiacetato-1,2-diamino(cyclohexane)platinum(II) (MIDP), and N-(2-hydroxyethyl)-iminodiacetato-1,2-diamino(cyclohexane)platinum (II) (HIDP). Fresh human tumor samples in the adhesive tumor culture system were utilized for this comparison. The equitoxic concentrations of all four drugs were derived based on their inhibitory activity against human bone marrow samples. For these normalized concentrations, CDDP proved to have a higher cytotoxic activity than its analogues. CBDCA's in vitro activity had a significant correlation with CDDP activity (r = 0.67) in vitro. However, the structurally similar substances MIDP and HIDP demonstrated a much greater degree of association (r = 0.90). Our data suggest that CBDCA, HIDP, and MIDP have overall less activity than CDDP when tested at equitoxic in vitro concentrations. Close association between CDDP and CBDCA also reflects known clinical experience with these two drugs, suggesting the method of comparison used here is probably appropriate. These conclusions, however, must be validated by clinical trials.

Comparison of antitumor activity of standard and investigational drugs at equivalent granulocyte-macrophage colony-forming cell inhibitory concentrations in the adhesive tumor cell culture system: an in vitro method of screening new drugs

We compared the in vitro growth inhibition of primary human tumor cells in the adhesive tumor cell culture system (ATCCS), exposed to the investigational agents caracemide, spirogermanium and taxol and to standard chemotherapy agents at equitoxic concentrations for granulocyte-macrophage colony-forming cells (GM-CFC) in vitro. Clinically active standard agents tested at up to GM-CFC 90% inhibitory concentrations (IC90) resulted in in vitro activity (greater than or equal to 50% tumor growth inhibition) in at least 30% of tumors tested. In vitro responses for taxol, caracemide and spirogermanium were 78%, 9% and 7%, respectively. This paper proposes a model that incorporates two hypotheses: (1) myelotoxic drugs which inhibit tumor growth at concentrations equal to or less than equitoxic GM-CFC ICs will demonstrate clinical activity; and (2) both myelotoxic and particular nonmyelotoxic drugs inactive in vitro at these doses will not be active clinically. If this drug screening concept is valid, taxol may be clinically more active than caracemide and spirogermanium.

Properties of transient degenerate four-wave mixing involving the relaxation effect: an investigation

A series of phenomenological relaxation equations have been introduced to describe the formation and decay of a grating. The influences of medium relaxation on the transient properties of degenerate four-wave mixing were studied theoretically and experimentally. As we studied the backward wave shape, the accumulation and smoothing effects were observed. The theory agreed well with the experimental results.

Pharmacologic assessment of regimen chemosensitivity in the soft-agar assay: effect of oxygen on human tumors

The influence of oxygen on the growth and the in vitro chemosensitivity of human tumor cells was studied in the soft-agar assay. Tumor cells of pancreatic and ovarian origin prefer a reduced oxygen atmosphere for colony formation, whereas those of pulmonary origin grow better in 20% oxygen. Depending on the physiologic oxygen tension and the histologic origin of a particular cancer type, the in vitro chemosensitivity of many drug obtained with the conventional culture system could be inadequately assessed. The in vitro responses of tumor cells to combinations of drugs were measured by the regimen efficacy index (REI) method. The REI delineates the possible regimen enhancement or regimen default based on the in vitro chemosensitivity of the individual agents tested in the assay. In vitro regimen enhancement was observed only in ascites incubated in a reduced oxygen atmosphere with two-drug combinations. However, regardless of the oxygen gradients used, regimen default was seen in cancer cells of solid tumors treated with all combinations of drugs tested. This study suggests further investigation on the effects of oxygen in the soft-agar assay, and proposes the novel use of the REI method for evaluating the in vitro regimen chemosensitivity of human tumor cells.