Biomedical subjects

D Fan

Publications and source records attributed to D Fan.

At least 127 records · Page 7Linked to original sources

PubMed1991

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.

Animals↗

PubMed1991

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.

Adenocarcinoma↗

PubMed1991

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.

Antineoplastic Agents↗

PubMed1990

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.

Animals↗

PubMed1990

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.

Carcinoembryonic Antigen↗

PubMed1990

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.

Animals↗

PubMed1990

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.

Blotting, Northern↗

PubMed1990

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.

Animals↗

PubMed1990

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.

Animals↗

PubMed1990

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.

Administration, Intravesical↗

PubMed1990

[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.

Anastomosis, Surgical↗

PubMed1990

Transient inhibition of liver regeneration in mice by transforming growth factor-beta 1 encapsulated in liposomes.

We determined whether transforming growth factor-beta 1 (TGF-beta 1) encapsulated in phosphatidylcholine and phosphatidylserine liposomes could inhibit the proliferative response of mouse liver subsequent to partial hepatectomy. C57BL/6 mice were hepatectomized (60%) or underwent laparotomy (control). Peak mitotic activity occurred 48 hr after hepatectomy, as did incorporation of [125I]IdUrd into dividing cells of the liver. The number of Kupffer cells in the regenerating liver was constant relative to liver size, and the uptake of circulating liposomes correlated with liver size and the number of Kupffer cells. Liposomes containing saline (control) or TGF-beta 1 were injected i.v. into hepatectomized mice 24 and 36 hr after the operation. Liposome-TGF-beta 1, but not control liposomes, significantly inhibited the uptake of [125I]IdUrd by liver cells when measured 48 hr after hepatectomy. However, by 72 hr after hepatectomy, the uptake of [125I]IdUrd in livers of mice treated with liposome-TGF-beta 1 was similar to or exceeded that found for hepatectomized mice injected with control liposomes. We conclude that liposomes containing TGF-beta 1 can postpone the proliferative response of regenerating mouse liver cells and are therefore suitable carriers for the in vivo use of TGF-beta 1.

Animals↗

PubMed1990

Superior antiproliferative effects mediated by interferon-alpha entrapped in liposomes against a newly established human lung cancer cell line.

The purpose of this study was to characterize the antiproliferative activity of a recombinant interferon-alpha (IFN-alpha) against a newly established human adenocarcinoma cell line (DMS-4C) and to determine whether IFN-alpha entrapped in multilamellar liposomes had superior antitumor effects compared with free IFN-alpha. Treatment of DMS-4C cells with 100 U/ml of free IFN-alpha resulted in 34% cytostasis. IFN-alpha encapsulated in phosphatidylcholine/phosphatidylserine multilamellar vesicles produced growth inhibition of 67%, which was significantly greater than that produced by free IFN-alpha or by control liposomes containing only medium combined with free IFN-alpha. Moreover, kinetic analysis revealed that to produce significant cytolysis, free IFN-alpha had to be incubated with target cells for at least 24 h, whereas IFN-alpha encapsulated into liposomes required only 30 min of exposure.

Adenocarcinoma↗

PubMed1989

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.

Carcinoma, Transitional Cell↗

PubMed1989

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.

Animals↗

PubMed1989

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.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1989

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.

Bleomycin↗

PubMed1989

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.

Animals↗