Antibody-dependent cellular cytotoxicity mediated by cetuximab against lung cancer cell lines.

PURPOSE: Epidermal growth factor receptor (EGFR) is commonly overexpressed in lung cancer. Cetuximab is a chimeric mouse-human antibody targeted against EGFR. Compared with its inhibitory properties, its immunologic mechanisms have not been well studied. In this study, we investigated the antibody-dependent cellular cytotoxicity (ADCC) activity of cetuximab against lung cancer cell lines. EXPERIMENTAL DESIGN: We studied the correlation between EGFR expression in lung cancer cell lines and the ADCC activity of cetuximab as well as the influence of interleukin-2 and chemotherapy on the ADCC activity. EGFR expression was measured by a quantitative flow cytometric analysis and immunohistochemistry. The ADCC activity was assessed by a 4-h (51)Cr release assay. Peripheral blood mononuclear cells, purified T cells, natural killer (NK) cells, and monocytes from healthy donors or lung cancer patients were used as effector cells. RESULTS: Fresh peripheral blood mononuclear cells exhibited cetuximab-mediated ADCC activity against lung cancer cell lines at a low concentration of cetuximab (0.25 microg/mL). A logarithmic correlation was observed between the number of EGFRs and ADCC activity. Even low EGFR expression, which was weakly detectable by immunohistochemistry, was sufficient for maximum ADCC activity, and further increases in EGFR expression on the target cells had no further effect on the ADCC activity. In addition, ADCC activity was enhanced by interleukin-2 mainly through activation of NK cells and was less susceptible to immunosuppression by chemotherapy than NK activity in lung cancer patients. CONCLUSIONS: These observations suggest the importance of ADCC activity as an immunologic mechanism of cetuximab in biological therapy for lung cancer patients.     

Arsenic trioxide cytotoxicity in steroid and chemotherapy-resistant myeloma cell lines: enhancement of apoptosis by manipulation of cellular redox state.

PURPOSE: We investigated the ability of pretreatment with buthionine sulfoximine (BSO) to overcome a priori resistance to arsenic trioxide (As(2)O(3)) in multiple myeloma (MM) cells and determine whether this was through an apoptotic mechanism that involves changes in the cellular redox state. EXPERIMENTAL DESIGN: Using a panel of dexamethasone and chemotherapy-resistant MM cell lines, we examined growth inhibition, induction of apoptosis, and changes in the redox state by As(2)O(3) alone or after preincubation with BSO. RESULTS: Whereas the sensitive cell lines showed 100% killing at 0.5 micromol/liter of As(2)O(3), the resistant cell lines required BSO pretreatment to achieve 100% killing at this dose. By comparison, the peak As(2)O(3) plasma concentration in acute promyelocytic leukemia in patients successfully treated was 5-7 micromol/liter with rapid decline to a sustained level of 1-2 micromol/liter. We demonstrated that BSO and As(2)O(3)-induced cytotoxicity was attributable to induction of apoptosis accompanied by activation of the death signals: caspases 3, 8, and 9. CONCLUSIONS: We have demonstrated that growth inhibition of highly resistant MM cell lines by As(2)O(3) is facilitated by BSO and that this effect is accompanied by caspase activation, presumably leading to activation of apoptosis. These data indicate that steroid and chemotherapy-resistant MM cell lines can be overcome by manipulation of the cellular redox state. Because BSO and As(2)O(3) can be used at clinically relevant concentrations, we believe that our observations may have important implications for the treatment of MM.     

The cytotoxicity of methyl protodioscin against human cancer cell lines in vitro

Methyl protodioscin (NSC-698790) was a furostanol saponin isolated from the rhizome of Dioscorea collettii var. hypoglauca (Dioscoreaceae), a Chinese herbal remedy for the treatment of cervical carcinoma, carcinoma of the urinary bladder, and renal tumors for centuries. To systematically evaluate its potential anticancer activity, methyl protodioscin was tested cytotoxicity in vitro against human cancer cell lines by the NCI's (National Cancer Institute) anticancer drug screen. As a result, methyl protodioscin showed strong cytotoxicity against most cell lines from solid tumors with GI50 < or = 10.0 microM, especially selectively against one colon cancer line (HCT-15) and one breast cancer line (MDA-MB-435) with GI50 < 2.0 microM but moderate cytotoxicity was shown against leukemia cell lines with GI50 10-30 microM. The data are consistent with the fact that the rhizome of D. collettii var. hypoglauca has been employed for the treatment of solid tumors rather than leukemia in China for centuries. Based on an analysis using the COMPARE computer program with methyl protodioscin as a seed compound, no compounds in the NCI's anticancer drug screen database have cytotoxicity patterns similar to those of methyl protodioscin, indicating a potential novel mechanism of anticancer action.     

Schedule-dependent synergism and antagonism between methotrexate and cytarabine against human leukemia cell lines in vitro.

Methotrexate (MTX) and cytarabine have been widely used for the treatment of acute leukemias and lymphomas for over 30 years. However, the optimal schedule of this combination is yet to be determined and a variety of schedules of the combination has been used. We studied the cytotoxic effects of MTX and cytarabine in combination against human leukemia cell lines at various schedules in vitro. The effects of the combinations at the concentration of drug that produced 80% cell growth inhibition (IC(80)) were analyzed using the isobologram method of Steel and Peckham. Simultaneous exposure to MTX and cytarabine for 3 days produced antagonistic effects in human T cell leukemia, MOLT-3 and CCRF-CEM, B cell leukemia, BALL-1, Burkitt's lymphoma, Daudi, promyelocytic leukemia, HL-60 and Philadelphia chromosome-positive leukemia, K-562 cells. Simultaneous exposure to MTX and cytarabine for 24 h produced antagonistic effects, sequential exposure to MTX for 24 h followed by cytarabine for 24 h produced synergistic effects, and the reverse sequence produced additive effects in both CCRF-CEM and HL-60 cells. Sequential exposure to MTX for 24 h followed by cytarabine for 3 days also produced synergistic effects in MOLT-3 cells. Cell cycle analysis supported these observations. Our findings suggest that the simultaneous administration of MTX and cytarabine is not appropriate and the sequential administration of MTX followed by cytarabine may be the optimal schedule of this combination.     

In vitro cytotoxicity of diorganotin (IV) trimethoxy-benzoates against sixty human NCl tumor cell lines.

Diethyl- and di-n-butyltin (IV) trimethoxybenzoates were tested in vitro at the National Cancer Institute, Bethesda, Maryland, USA, for cytotoxic activity against a panel of 60 human cell lines. The di-n-butylin compounds are more active in vitro against human tumor cell lines than their diethyltin analogs.     

Taxol cytotoxicity on human leukemia cell lines is a function of their susceptibility to programmed cell death

Taxol is the prototype of a class of antineoplastic drugs that target microtubules. It enhances tubulin-monomer polymerization and stabilizes tubulin polymers, increasing the fraction of cells in the G2 or M phase of the cell cycle. We report that treatment of HL-60 and U937 myeloid cell lines with 1–10 M taxol induces DNA fragmentation and the appearance of morphological features consistent with the process of apoptosis. Taxol-induced apoptosis is inhibited neither by cycloheximide nor by actinomycin D and therefore appears to be independent of new protein synthesis. Taxol causes arrest in the G2 phase of the cell cycle and affects cell viability but does not induce DNA fragmentation in the K562 erythromyeloid cell line. Protein-synthesis inhibitors, colcemid, ionomycin, and starvation, known to trigger apoptosis, proved ineffective as well. These results suggest that the antineoplastic effect of taxol is mediated in susceptible cell lines by induction of the apoptotic machinery and that K562 partial resistance may depend upon the intrinsic inability of these tumor cells to undergo apoptosis.Abbreviations CHX cycloheximide - Act D actinomycin D - PI propidium iodide     

In vitro activity of dimethylarsinic acid against human leukemia and multiple myeloma cell lines

PURPOSE: Arsenic trioxide (As(2)O(3)), an inorganic arsenic compound, has recently been approved for the treatment of relapsed or refractory acute promyelocytic leukemia. However, systemic toxicity associated with As(2)O(3) treatment remains a problem. Inorganic arsenic is detoxified in vivo by methylation reactions into organic arsenic compounds that are less toxic. METHODS AND RESULTS: We investigated the antiproliferative and cytotoxic activity of dimethylarsinic acid (DMAA), an organic arsenic derivative and major metabolic by-product of As(2)O(3), against a panel of eight leukemia and multiple myeloma cell lines. As(2)O(3) was tested in comparison. In clonogenic assay, the average concentration of DMAA that suppressed cell colony growth by 50% was 0.5-1 m M, while for As(2)O(3) it was on average 1-2 microM. At those concentrations DMAA and As(2)O(3) had significantly less effect on colony growth of normal progenitor cells. Cytotoxic doses of DMAA and As(2)O(3) in 3-day trypan blue dye exclusion assay experiments were similar to doses effective in clonogenic assay. Assessment of apoptosis by annexin V assay revealed a high rate of apoptosis in all cell lines treated with DMAA and As(2)O(3), but significantly less effect on normal progenitor cells. DMAA, unlike As(2)O(3), had no effect on the maturation of leukemic cells. CONCLUSIONS: DMAA exerts differential antiproliferative and cytotoxic activity against leukemia and multiple myeloma cells, with no significant effect on normal progenitor cells. However, concentrations of DMAA needed to achieve such efficacy are up to 1000 times those of As(2)O(3). Evaluation of novel organic arsenic that would combine the high efficacy of As(2)O(3) and the low toxicity of DMAA is warranted.     

A monoclonal antibody against the c-erbB-2 protein enhances the cytotoxicity of cis-diamminedichloroplatinum against human breast and ovarian tumor cell lines.

A monoclonal antibody (TAb 250) specific to an extracellular epitope of the c-erbB-2 protein (gp185) inhibited the in vitro proliferation of human breast tumor cell lines that overexpress c-erbB-2 in a dose-dependent manner. Treatment of cells with combinations of cis-diammedichloroplatinum (CDDP) and TAb 250 resulted in a significantly enhanced cytotoxic effect. This synergistic cytotoxicity was apparent over a wide range of antibody concentrations (200 pg/ml-100 micrograms/ml) including concentrations that showed no inhibitory effect alone. TAb 250 did not increase the cytotoxic effect of CDDP in a cell line exhibiting no detectable level of gp185. Athymic mice bearing s.c. xenografts of human tumor cells expressing high levels of gp185 showed a greatly enhanced inhibition of tumor growth when treated with TAb 250 and CDDP compared to treatment with the antibody or CDDP alone. This effect was specific inasmuch as TAb 250 did not enhance the growth-inhibitory effect of CDDP on tumor xenografts which were not expressing gp185.     

Comparative in vitro cytotoxicity of taxol and Taxotere against cisplatin-sensitive and-resistant human ovarian carcinoma cell lines

Summary Using the sulforhodamine B assay, we compared the cytotoxic properties of the novel microtubule agent taxol and the semi-synthetic related compound Taxotere in nine human ovarian-carcinoma cell lines, including three pairs of cell lines rendered resistant to cisplatin or carboplatin. In addition, the cytotoxicity of the commonly used anticancer drugs cisplatin and adriamycin and the topoisomerase II inhibitor etoposide was determined. The results of continuous drug exposure showed that taxol [mean concentration producing 50% growth inhibition (IC₅₀), 1.1×10^–9 m; range, 2.8×10^–9–5×10^–10 m and Taxotere (mean IC₅₀, 5.1×10^–10 m; range, 7.2–3.3×10^–10 m) were >1,000 times more cytotoxic than either cisplatin (mean IC₅₀, 3.1×10^–6 m;P<0.05) or etoposide (mean IC₅₀, 2.3×10^–6 m;P<0.05) and >100 times more cytotoxic than Adriamycin (mean IC₅₀, 6.9×10^–8 m;P<0.05). Taxotere was more cytotoxic than taxol; following continuous exposure, the mean difference across the cell lines was 2 orders of magnitude (range, 1.1–3.9 orders of magnitude for individual lines). Although this difference did not reach statistical significance for any individual cell line (P values ranged from 0.17 for HX/62 to 0.9 for OVCAR-3), when all IC₅₀ values for the 96-h experiments were pooled, Taxotere was found to be significantly more potent than taxol (P=0.05). Following 2 h exposure, the mean cytotoxicity of Taxotere was 3.9-fold > that of taxol across the nine lines (range, 0.75- to 10-fold;P<0.05 for the CH1 cell line; overall pooled IC₅₀ data,P=0.05). Although a 71-fold range of sensitivity to cisplatin was observed across the six parent cell lines (IC₅₀ most resistant line/IC₅₀ most sensitive line), this was largely abolished by treatment with taxol (5.6-fold range) and Taxotere (2.2-fold rante). Following continuous exposure of the three pairs of lines exhibiting acquired resistance to platinum, no cross-resistance with either Taxotere or taxol was found (resistance factors, <1.5). In the 41M and 41McisR pair of lines, in which previous studies have shown resistance to be due to reduced platinum accumulation, taxol and Taxotere exhibited some collateral sensitivity (resistance factors, 0.69 and 0.66, respectively). Taxotere and, particularly, taxol showed a pronounced concentration times exposure duration (CxT) dependence as compared with cisplatin (P<0.05). The mean loss in potency across the nine lines for 2 vs 96 h exposure was 97 for taxol, 35 for Taxotere, 30 for Adriamycin and only 9.9 for cisplatin. However, these differences in potency loss observed between taxol and Taxotere did not reach statistical significance (P=0.18). These data indicate that Taxotere is approximately 2 times more cytotoxic than taxol and shows an encouraging lack of cross-resistance in three cell lines exhibiting acquired resistance to cisplatin and carboplatin.This study was supported by grants to the Institute of Cancer Research, Royal Cancer Hospital, from the Cancer Research Campaign and, through the European Organisation for Research and Treatment of Cancer (EORTC) Clonogenic Assay Screening Group, by grant 90031 from Rhone-Poulenc Rorer.     

PLA表位肽免疫微球诱导CTL对肝癌细胞的杀伤作用

目的〖HT5"SS〗：考察两种载肽聚乳酸（(polylatic acid, PLA)免疫微球M1（hAFP158~166）和M2（hAFP218~226）在体外诱导特异性CTL的能力及其对肝癌细胞的杀伤作用。〖HT5W〗方法： 〖HT5”SS〗制备分别荷载表位肽hAFP158~166、、hAFP218~226的PLA免疫微球M1和M2,体外刺激HLAA2+健康志愿者的外周血单个核细胞（PBMC）作为效应细胞,实验分为3组：对照组、hAFP表达组和hAFP阴性组。采用标准51Cr释放法检测CTL杀伤活性。〖HT5W〗结果：〖HT5"SS〗两种免疫微球在体外均能刺激人PBMC增殖,形成大量可见克隆;两者诱导的效应细胞对hAFP＋的荷肽T2细胞、HepG2和Alexander的杀伤率均达75％以上,均显著高于不表达hAFP的膀胱癌细胞BTT和未荷肽的T2细胞,差异非常显著（P<0.01）,而两者杀伤活性之间没有明显差异（P>0.05）。〖HT5W〗结论：〖HT5"SS〗两种载肽聚乳酸免疫微球均能在体外诱导产生特异性CTL,并对表达靶抗原的肝癌细胞有较强杀伤作用。     

Potentiation by tumor necrosis factor of mitoxantrone cytotoxicity to human ovarian cancer cell lines.

The cytotoxic activity of human recombinant tumor necrosis factor (rHuTNF) (from 0.01 to 10000 U/ml) was assayed on six human ovarian cancer cell lines and one human cervical carcinoma cell line using a crystal violet assay. rHuTNF was cytotoxic to four cell lines (A2780, A2774, SW626, PA1), while 3 cell lines (IGROV1, SKOV3, Me180) were marginally sensitive to its activity. However, under the same experimental conditions rHuTNF markedly enhanced the cytotoxicity of mitoxantrone, a chemotherapeutic drug targeted at DNA topoisomerase II, in six cell lines. The potentiation of mitoxantrone cytotoxicity was not caused by increased drug accumulation after rHuTNF treatment. No significant increase in cytotoxicity to Me180 cell line was seen when rHuTNF was added to mitoxantrone.     

Schedule-dependent modulation of idarubicin cytotoxicity by lonidamine in human lymphoma cell lines

The ability of lonidamine (LND), an energolytic derivative of indazol-carboxylic acid, to modulate the cytotoxic activity of idarubicin (IDA) and doxorubicin (DX) was investigated in two human lymphoma cell lines (H9 and U937). A different pattern of interaction between the drugs was observed as a function of treatment sequence. Specifically, a 24-h postincubation with a non-cytotoxic concentration of LND (75 mu M) increased the activity of a 1-h anthracycline treatment in both cell lines. However, the extent of potentiation for IDA was more than twofold that of DX. No enhancement of anthracycline activity was observed when LND preceded IDA. For comparative purposes, the modulating effect of all-trans-retinoic acid (ATRA) on the cytotoxicity of IDA was evaluated according to different treatment schemes in both lymphoma cell lines. In U937 cells, which undergo monocytic differentiation after exposure to retinoids, a marked increase in LDA activity was obtained following a 48-h postincubation with 1.5 mu M ATRA. No potentiation of anthracycline activity was obtained using the opposite drug sequence. In H9 cells, no significant interference between ATRA and IDA was observed independent of the modality of drug administration. The ability of LND to potentiate IDA activity, and the consideration that LND causes side effects different from those caused by anthracyclines, make this compound an attractive candidate for multidrug combination therapy in hematological neoplasms.     

Syngeneic and allogeneic cell-mediated cytotoxicity against marek's disease lymphoblastoid tumor cell lines

Cell-mediated cytotoxicity (CMC) of lymphocytes obtained from chickens infected with Marek's disease (MD) virus against allogeneic MD lymphoblastoid cell lines has been reported by several research groups. Recently, we established a number of cell lines from MD tumors obtained from highly inbred chickens and characterized for major and minor histocompatibility antigens. Allogeneic versus syngeneic CMC was studied using those cell lines and lymphocytes obtained from chickens 6-8 days post infection with 5B-1, a non-oncogenic MD virus. Allogeneic cytotoxicity could be easily demonstrated, while syngeneic cytotoxicity was a rare event. However, increase of the CMC assay period from 4 to 8 h did enhance syngeneic cytotoxicity. Cold inhibition assays demonstrated that the allogeneic cytotoxicity was directed against alloantigens present on spleen lymphocytes sharing the same major histocompatibility antigens as the target cells. Cytotoxicity was not influenced by the sex of either target or effector cells or by the level of virus infectivity of the effector cells.     

Geldanamycin-induced cytotoxicity in human colon-cancer cell lines: evidence against the involvement of c-Src or DT-diaphorase

We investigated two of the major proposed modes of action of the benzoquinoid ansamycin geldanamycin using a pair of human colon-carcinoma cell lines, BE and HT29. One potential mechanism of action in colorectal cancer is the inhibition of c-Src kinase activity, since this proto-oncogene is hyperexpressed in human large-bowel tumours. Our results show that despite the 9-fold higher level of c-Src kinase activity found in HT29 cells, there was only a 1.4-fold difference in cytotoxicity as compared with BE cells, the latter being the most sensitive. Moreover, even at concentrations of geldanamycin that resulted in cell kill of 80% or more after a 24-h period of exposure, there was no effect on␣␣␣ c-Src kinase activity in HT29 cells, although c-Src protein was depleted at supralethal levels of exposure. We also investigated the metabolism of the quinone moiety of geldanamycin by DT-diaphorase, an enzyme that activates certain quinone antibiotics such as mitomycin C and is hyperexpressed in colorectal cancer cells. Geldanamycin was shown to be a substrate for␣DT-diaphorase present in HT29 cells. However, the lack of a major differential in cytotoxicity between HT29 and BE cells indicates that this is unlikely to be pharmacologically significant, since the former contains high levels of enzyme activity, whereas BE cells have no significant activity due to a point mutation in the DT-diaphorase (NQO1) gene. Although reduction of geldanamycin was also catalysed by non-DT-diaphorase reductases in HT29 and BE cells, providing the potential for free radical induction, this is unlikely to be significant since studies previously reported by us elsewhere showed that cells exposed to geldanamycin exhibited no evidence of DNA damage. Thus, as far as the mode of action of geldanamycin in human colon-carcinoma cells is concerned, the present results rule out two major possibilities, namely, the involvement of c-Src tyrosine kinase inhibition and DT-diaphorase metabolism. Received: 20 April 1997 / Accepted: 5 September 1997     

Enhancement of natural killer cell effector functions against selected lymphoma and leukemia cell lines by dasatinib

As NK cell immunotherapy is still poorly successful, combinations with drugs enhancing NK cell activity are of major interest. NK large granular lymphocyte expansions associated with improved survival have been described under monotherapy with the Bcr-Abl/Src inhibitor dasatinib, which inhibits NK cell functions in vitro. As Src kinases play a major role in inhibitory and activating signaling pathways of NK cells, both outcomes appear plausible. To clarify these contradictory observations and potentially enable the use of dasatinib as adjuvant, we analyzed how clinically relevant doses promote NK cell effector functions. Polyclonal human NK cells were studied ex vivo. Functional outcomes assessed included conjugate formation, calcium flux, receptor regulation, cytokine production, degranulation, cytotoxicity, apoptosis induction and signal transduction. While dasatinib inhibits NK cell effector functions during functional assays, 24 hr pretreatment of NK cells followed by washout of dasatinib, led to dose-dependent enhancement of cytokine production, degranulation marker expression and cytotoxicity against selected lymphoma and leukemia cell lines. Mechanistically, this was neither due to an altered viability of NK cells nor increased NKG2D, LFA-1 or conjugate formation with target cells. Receptor proximal signaling events were inhibited. However, a slight time dependent enhancement of Vav phosphorylation was observed under certain circumstances. The shift in Vav phosphorylation level may be one major mechanism for NK cell activity enhancement induced by dasatinib. Our findings argue for a careful timing and dosing of dasatinib application during leukemia/lymphoma treatment to enhance NK cell immunotherapeutic efforts.     

Potentiation of melphalan cytotoxicity in human ovarian cancer cell lines by glutathione depletion

The effectiveness of alkylating agents in the treatment of ovarian cancer is limited by the frequent development of drug resistance. In order to examine the mechanisms of resistance and potential ways in which this resistance could be overcome, we have developed a human ovarian cancer cell line, 1847ME, resistant to the bifunctional amino acid nitrogen mustard, melphalan. A 4-fold higher concentration of melphalan was required to produce an equivalent reduction in tumor colony formation in 1847ME cells as compared to the parent melphalan-sensitive line A1847. The magnitude of resistance in 1847ME was similar to that observed in the cell lines NIH:OVCAR-2, NIH:OVCAR-3, and NIH:OVCAR-4 which were derived from ovarian cancer patients clinically resistant to alkylating agents. There was no detectable difference in melphalan uptake between A1847 and 1847ME. The cellular content of the inactive dihydroxy melphalan metabolite, however, was two times greater in 1847ME compared to A1847. Levels of the principal intracellular thiol, glutathione, were found to be 2-fold greater in 1847ME than in A1847, and to be similarly elevated in the OVCAR lines. Depletion of glutathione by incubation of the cells in cystine-free medium or in the presence of the specific inhibitor of glutathione synthesis, DL-buthionine-S,R-sulfoximine, was accompanied by a marked increase in melphalan cytotoxicity. Doses of DL-buthionine-S,R-sulfoximine which were only minimally cytotoxic were associated with complete reversal of the induced resistance to melphalan in 1847ME. Synergism between melphalan and DL-buthionine-S,R-sulfoximine was also demonstrated in the OVCAR cell lines derived from previously treated ovarian cancer patients. The reversal of induced resistance to melphalan by modulation of glutathione levels is of potential clinical relevance. In addition, these cell lines provide a useful model system in which to study further the mechanisms of alkylating agent resistance in human tumors.     

Enhancement of fluorinated pyrimidine-induced cytotoxicity by leucovorin in human lung cancer cell lines

Reduced folates have been shown to increase the cytotoxicity of 5-fluorouracil (FUra) by stabilizing the fluorodeoxyuridine monophosphate:thymidylate synthase complex, thus increasing the block in the DNA synthetic pathway. Using an in vitro tetrazolium colorimetric (MTT) cytotoxic assay, we tested the effects of FUra and 5-fluorodeoxyuridine (FUdR) with and without leucovorin (LV) on a panel of 7 human lung cancer cell lines. LV at a concentration of 20 microM enhanced the cytotoxicity of FUra and of FUdR in all of the cell lines. Quantitatively, LV had a higher degree of enhancement on FUdR than on FUra cytotoxicity in 6 cell lines. There was equivalent enhancement in the only remaining line. The differential effects of LV on the cytotoxicity of FUra vs. FUdR in these lung carcinoma lines contrasts with a quantitatively similar enhancement of cytotoxicity between FUra and FUdR in colon cancer lines previously reported from our laboratory. This suggests that the metabolism of FUra may be different in these lung cancer cell lines.     

Antigens present on human myeloid leukemia cell lines

Two human acute myelogenous leukemia cell lines have recently been established: KG-1 and HL-60. Both lines retain the morphology and cytochemistry of myeloid cells, are not infected with EB virus, and respond to colony-stimulating activity (CSA) with increased colony formation in soft-gel culture. The K 562 cell line is composed of undifferentiated blast cells which are rich in glycophorin and may be induced to produce human fetal and embryonic hemoglobin. We used a variety of antisera to characterize the antigen composition of the leukemic colony-forming cells (CFC) and the general population of leukemic cells. Cells were incubated with antisera and complement, washed, plated in agar, and the colonies counted after 12 days' incubation. Culture data were correlated with the results obtained using direct and indirect immunofluorescence and dye exclusion microcytotoxicity.The majority of KG-1 cells, including CFC, expressed the ‘Ia-like’ antigen. The HL-60 and K562 cells did not express the Ia antigen, although indirect evidence using cytogenetic and isoenzyme studies suggests that the HL-60 gene locus for the antigen was probably intact.We found that the leukemia CFC had the HLA-A and -B antigens as did the general leukemia cell population. The leukemia CFC did not express a T-lymphocyte antigen, certain erythrocyte antigens, nor antigens associated with acute lymphocytic leukemia. HL-60 cells underwent morphological and functional maturation in the presence of DMSO, but no change in surface antigenic composition was noted. All antigens expressed on the leukemia CFC were also present on the general cell population.