Transduction of KAI1/CD82 cDNA promotes hematogenous spread of human lung-cancer cells in natural killer cell-depleted SCID mice.

KAI1, which is identical to CD82, was initially identified as a metastasis-suppressor gene for human prostate cancer, and its expression is reported to be a favorable prognostic factor for operable human lung cancer. In this study, we examined the functional role of KAI1/CD82 in the late phase of metastatic spread of human lung-cancer cells. For this, KAI1/CD82 cDNA was introduced into KAI1/CD82 low-expressing human lung-cancer cell lines, SBC-3 and PC-14, and then the metastatic potential of the transformants was analyzed by i.v. inoculation of KAI1/CD82-transduced cells, SBC-3/KAI1 and PC-14/KAI1, into NK cell-depleted SCID mice. Contrary to our expectations, KAI1/CD82 gene transfer promoted multiorgan metastasis of i.v.-inoculated human lung-cancer cells, while s.c. tumor growth was unaffected. Cancer cells from metastatic tumors of NK cell-depleted SCID mice injected i.v. with SBC-3/KAI1 expressed appreciable cell-surface KAI1/CD82, and cells not expressing KAI1/CD82 (revertants) were not detected in the tumors. Our findings indicate that under conditions where the host's natural cytotoxicity is suppressed, KAI1/CD82 may enhance the formation of tumors by circulating lung-cancer cells at metastatic sites.

A new quinoline derivative MS-209 reverses multidrug resistance and inhibits multiorgan metastases by P-glycoprotein-expressing human small cell lung cancer cells.

Development of distant metastases and acquired multidrug resistance (MDR) are major problems in therapy for human small cell lung cancer (SCLC). MS-209 is a novel quinoline compound, which reverses P-glycoprotein (P-gp)-mediated MDR. We previously reported that MS-209 reversed in vitro MDR of human SCLC (SBC-3 / ADM and H69 / VP) cells expressing P-gp. In the present study, we determined the therapeutic effect of MS-209 in combination with chemotherapy against multiorgan metastases of MDR SCLC cells. SBC-3 / ADM cells expressing P-gp were highly resistant to etoposide (VP-16), adriamycin (ADM), and vincristine (VCR) in vitro, compared with parental SBC-3 cells lacking P-gp expression. MS-209 restored chemosensitivity of SBC-3 / ADM cells to VP-16, ADM, and VCR in a dose-dependent manner in vitro. Intravenous injection with SBC-3 or SBC-3 / ADM cells produced metastatic colonies in the liver, kidneys and lymph nodes in natural killer (NK) cell-depleted severe combined immunodeficiency (SCID) mice, though SBC-3 / ADM cells more rapidly produced metastases than did SBC-3 cells. Treatment with VP-16 and ADM reduced metastasis formation by SBC-3 cells, whereas the same treatment did not affect metastasis by SBC-3 / ADM cells. Although MS-209 alone had no effect on metastasis by SBC-3 or SBC-3 / ADM cells, combined use of MS-209 with VP-16 or ADM resulted in marked inhibition of metastasis formation by SBC-3 / ADM cells to multiple organs. These findings suggest that MS-209 reversed the MDR of SBC-3 / ADM cells, but not SBC-3 cells, growing in the various organs, and inhibited metastasis formation in vivo. Therefore, this chemosensitizing agent, MS-209, may be useful for treatment of refractory SCLC patients with multiorgan metastases.

Humanized anti-ganglioside GM2 antibody is effective to induce antibody-dependent cell-mediated cytotoxicity in mononuclear cells from lung cancer patients.

Ganglioside GM2 is one of the major gangliosides expressed on the cell surface of human tumors including lung cancer. We have previously reported that a mouse-human chimeric monoclonal antibody (mAb), KM966, against GM2 promotes the lysis of lung cancer cells by human blood mononuclear cells (MNC) of healthy donors. In this study, we examined antibody-dependent cell-mediated cytotoxicity (ADCC) of MNC, using KM966 mAb and its humanized counterpart, KM8969, in 16 lung cancer patients and 18 control patients. The ADCC activity was assessed by 4-h (51)Cr release from GM2 positive SBC-3 small cell lung cancer cells. MNC from lung cancer patients exhibited similar ADCC activity to those from control patients when KM966 and KM8969 were used as mAb. Moreover, effective ADCC activity was observed even in MNC from advanced lung cancer patients. These observations suggest the potential activity of humanized anti-GM2 mAb (KM8969), as well as chimeric KM966, in biological therapy for lung cancer patients.

Augmentation by interleukin-18 of MHC-nonrestricted killer activity of human peripheral blood mononuclear cells in response to interleukin-12.

Interleukin (IL)-18 is a novel cytokine with pleiotropic functions. In the present study, we examined the induction of the killer activity of peripheral blood mononuclear cells (MNC) against lung cancer cell lines upon treatment with IL-18 in combination with IL-12. Cytotoxic activity was measured by standard (51)Cr release assay. IL-18 (100 ng/ml) was found to significantly augment IL-12-induced killer activity in a MHC-nonrestricted manner against allogeneic NK-resistant Daudi cells and lung cancer cell lines: SBC-3, RERF-LC-AI and A549. IL-18 could augment IL-12-induced killer activity both at the optimal as well as suboptimal doses of the latter. However, IL-18 was found to have little effect on the killer activity of MNC induced by optimal or suboptimal dose of IL-2 or IL-15. Treatment of MNC with IL-18 in combination with IL-12 for a period of more than 4 days was observed to optimally induce the killer activity. As for induction of IFN-gamma production by MNC, IL-18 augmented that induced by IL-2 and IL-15, as well as that induced by IL-12. These results show the potential of IL-18 in combination with IL-12 for clinical application in treatment of cancer.

Human interferon-gamma enhances expression of ganglioside GM2 on human lung cancer cells and their susceptibility for antiganglioside GM2 monoclonal antibody-dependent cellular cytotoxicity.

Interferons are known to modulate several cellular functions by the induction of various proteins. In this study, we demonstrated that human interferon-gamma (HuIFN-gamma) enhanced the expression of ganglioside GM2 (GM2), which is a kind of tumor-associated antigen substantially expressed in human lung cancer and that human lung cancer cells expressing GM2 became more susceptible to anti-GM2 monoclonal antibody (mAb)-dependent tumor cell killing mediated by human effector cells after HuIFN-gamma treatment. GM2 expression on human lung cancer cells treated with or without HuIFN-gamma was measured by flow cytometry. The antibody-dependent cellular cytotoxicity (ADCC) activity was assessed by 4-h 51Cr release assay. HuIFN-gamma enhanced GM2 expression on human small-cell lung cancer (SCLC), SBC-3, and human non-small-cell lung cancer (NSCLC), A549 cells in a dose-dependent manner. The optimal concentration of HulIFN-gamma was 1,000 U/ml. The effect of HulFN-gamma reached maximum after 4 days of culture. HulFN-gamma did not have any effect to enhance the expression of other gangliosides in SBC-3 cells. No other cytokines used in this study modulated GM2 expression in SBC-3 cells. Anti-GM2 mAb-dependent ADCC activities induced by lymphocytes and monocytes were more potent against IFN-gamma-treated SBC-3 and A549 cells than nontreated cells. Taken together, HulFN-gamma combined with anti-GM2 mAb may be useful for immunotherapy against GM2-positive human lung cancer.

Immunological circumvention of multiple organ metastases of multidrug resistant human small cell lung cancer cells by mouse-human chimeric anti-ganglioside GM2 antibody KM966.

serum against SBC-3/DOX cells to a similar extent compared with parental SBC-3 cells. Pretreatment of human effector cells with various cytokines induced further enhancement of the KM966-dependent ADCC against SBC-3/DOX cells. Intravenous injection of SBC-3 or SBC-3/DOX cells into natural killer (NK) cell-depleted severe combined immunodeficient (SCID) mice developed metastases in multiple organs (liver, kidneys and lymph nodes). Interestingly, SBC-3/DOX cells produced metastases more rapidly than SBC-3 cells, suggesting more aggressive phenotype of SBC-3/DOX cells than their parental cells in vivo. Systemic treatment with KM966, given on days 2 and 7, drastically inhibited the formation of multiple-organ metastases produced by both SBC-3 and SBC-3/DOX cells, indicating that KM966 can eradicate metastasis by SCLC cells irrespective of MDR phenotype. These findings suggest that the mouse-human chimeric KM966 targets the GM2 antigen, and might be useful for the immunological circumvention of multiple-organ metastases of refractory SCLC.

Bone metastasis model with multiorgan dissemination of human small-cell lung cancer (SBC-5) cells in natural killer cell-depleted SCID mice.

Lung cancer is commonly associated with multiorgan metastasis, and bone is a frequent metastatic site for lung cancer. Nevertheless, no bone metastasis model of lung cancer with multiorgan dissemination is available, which could provide opportunity to study the molecular pathogenesis. We examined the abilities of eight human lung cancer cell lines injected intravenously into natural killer (NK) cell-depleted SCID mice to generate metastatic nodules in bone and multiple organs, and explored the correlation of the parathyroid hormone-related protein (PTHrP) with the bone metastasis. Although all the small-cell carcinoma cell lines (SBC-5, SBC-3, SBC-3/ADM, H69, H69/VP) formed metastatic nodules in multiple organs (liver, kidney, and lymph nodes), only SBC-5 cells reproducibly developed bone metastases. Squamous cell carcinoma (RERF-LC-AI) cells metastasized mainly into the liver and kidneys, whereas adenocarcinoma (PC-14, A549) mainly produced colonies in the lungs. As assessed by X-ray photography, the osteolytic bone metastases produced by SBC-5 cells were detected as early as on day 28, and all recipient mice developed bone metastasis by day 35. The expression of PTHrP in eight cell lines was directly correlated with the formation of bone metastasis. No correlation was observed between the formation of bone metastasis and the expression of other metastasis-related cytokines (IL-1, IL-6, IL-8, IL-10, IL-11, TNF-alpha, VEGF, M-CSF). Consistent with the formation of bone metastasis by SBC-5 cells, the levels of PTHrP and calcium in the mouse serum were increased in a time-dependent manner, suggesting that PTHrP produced by human lung cancer may play a crucial role in the formation of bone metastasis and hypercalcemia. These findings indicate that a bone metastasis model of SBC-5 cells may be useful for clarifying the molecular aspects of the metastatic processes in different organ microenvironments and the development of therapeutic modalities for lung cancer patients with bone metastases.

Therapeutic efficacy of a new topoisomerase I and II inhibitor TAS-103, against both P-glycoprotein-expressing and -nonexpressing drug-resistant human small-cell lung cancer.

We examined the effect of a novel topoisomerase I and II (topo I and II) inhibitor, TAS-103, on P-glycoprotein (P-gp)-expressing and -nonexpressing drug-resistant human small-cell lung cancer (SCLC) cells in vitro and in vivo. We observed that TAS-103 was effective in inhibiting in vitro proliferation of human SCLC (SBC-3 and H69) cells and their drug-resistant variants SBC-3/ADM or SBC-3/CDDP and H-69/VP, respectively. SBC-3/ADM and H-69/VP expressed high P-gp, whereas SBC-3/CDDP did not. TAS-103 also effectively reduced the tumor growth (more than 50% inhibition) of the parental as well as MDR SCLC cells grown SC in nude mice. Adriamycin (ADM) and cisplatin (CDDP), on the other hand, were effective only against the parental cells, while these drugs failed to inhibit the respective drug-resistant variants in vitro or in vivo. TAS-103 was observed to induce apoptosis dose dependently in the parental as well as drug-resistant SCLC cells as analyzed after 48 h of in vitro treatment, suggesting that the stabilization of cleavable topo I- or II-DNA complexes by topo I and II inhibitors like TAS-103 is followed by apoptosis of the cells. Overall, our study suggests that TAS-103 may have clinical application against drug-resistant human SCLC.

Apoptosis induction of human lung cancer cell line in multicellular heterospheroids with humanized antiganglioside GM2 monoclonal antibody.

The chimeric antiganglioside GM2 monoclonal antibody (MAb) KM966, which showed high effector functions such as complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC), potently suppressed growth and metastases of GM2-positive human cancer cells inoculated into mice. To further improve the therapeutic efficacy of the anti-GM2 MAb in humans, we constructed a humanized anti-GM2 MAb, KM8969. The humanized KM8969 was more efficient in supporting ADCC against GM2-positive human cancer cell lines than the chimeric KM966, whereas complement-dependent cytotoxicity was slightly reduced in the humanized KM8969. In addition, the humanized KM8969 was shown to exert potent ADCC mediated by both lymphocytes and monocytes. To investigate the effect of the humanized KM8969 on the biological function of GM2 in the condition physiologically mimicking formation and growth of cancer masses, the heterospheroids composed of normal human dermal fibroblasts and GM2-positive human lung cancer cells were developed. Interestingly, the humanized KM8969 gave rise to growth inhibition of heterospheroids without dependence of the effector functions. Morphological and immunocytochemical analysis suggested that the inhibitory effect was due to the apoptosis of GM2-positive cancer cells in the heterospheroids. The result indicates that GM2 captured by the antibody on the cell surface loses its physiological function that plays a critical role in maintaining the three-dimensional growth of cancer cells in contact with its own cells or other type of cells in a microenvironment. The humanized KM8969, which can destroy the cancer cells via blocking functional GM2 on the cell surface as well as the effector functions, would have extraordinary potential in human cancer therapy.

Production of interleukin-10 by alveolar macrophages from lung cancer patients.

Interleukin (IL)-10 is known to be an autoregulatory factor of functions of monocyte macrophages. The purpose of this study was to determine whether IL-10 production by alveolar macrophages (AMs) is altered in patients with lung cancer. AMs were obtained by bronchoalveolar lavage from 25 patients with lung cancer and 14 control patients. The production of IL-10 by AMs was quantitated by enzyme immunoassay with or without stimulation with lipopolysaccharide (LPS). No significant difference in spontaneous and LPS-stimulated IL-10 production by AMs was observed between lung cancer patients and control patients (mean +/- SEM; 288.0 +/- 56.7 vs. 249.6 +/- 58.4 pg ml-1). IL-10 production of LPS-stimulated AMs was not impaired even in lung cancer patients with systemic metastasis. IL-4 failed to suppress LPS-induced production of IL-10 by AMs both in control patients and in lung cancer patients. In eight patients with lung cancer, IL-10 production by AMs was estimated before and after systemic chemotherapy and IL-10 production by LPS-stimulated AMs tended to increase after systemic chemotherapy from 152.3 +/- 51.9 to 278.0 +/- 112.8 pg ml-1. As IL-10 is a potent inhibitor of tumour angiogenesis, an important process of tumour progression, these results suggest that, even in advanced cancer patients, macrophages can produce potent angiogenesis inhibitor and systemic chemotherapy may augment this inhibitory activity in the lung.

Combined therapy with anti-P-glycoprotein antibody and macrophage colony-stimulating factor gene transduction for multiorgan metastases of multidrug-resistant human small cell lung cancer in NK cell-depleted SCID mice.

Our aim was to determine the antimetastatic potential of anti-P-glycoprotein (P-gp) antibodies (Abs) against multidrug-resistant (MDR) human small cell lung cancer (SCLC) cells expressing P-gp. Human SCLC cells H69 (P-gp negative) and its etoposide-resistant variant H69/YP (P-gp positive) were used. H69 and H69/VP cells injected i.v. metastasized to the liver, kidneys and systemic lymph nodes of NK cell-depleted severe combined immunodeficient (SCID) mice. H69/VP cells, but not H69 cells, were resistant to treatments with vindesine. Treatment with mouse-human chimeric anti-P-gp Ab (MH162) and its mouse counterpart (MRK-16) reduced metastasis of H69/VP cells in various organs and prolonged the survival of tumor-bearing mice, although they were less effective if injected at late times (after 28 days). Treatment with another mouse anti-Pgp Ab, MRK-17, was effective only against liver metastasis. MH162 and MRK-16 efficiently induced Ab-dependent cellular cytotoxicity (ADCC) by peritoneal macrophages against H69/VP cells in vitro, but MRK-17 was less effective, in accordance with their in vivo antimetastatic potential. Gene transfection of macrophage colony-stimulating factor (M-CSF) into H69/VP cells to augment macrophage-mediated ADCC resulted in inhibition of metastasis to the liver and lymph nodes, but not kidneys. Combined treatment with a low dose of MRK-16 completely cured metastasis of M-CSF transfectant, but not of the mock transfectant. Our findings suggest that while anti-P-gp Abs had antimetastatic potential against SCLC cells expressing P-gp, combined treatment with M-CSF gene transduction to augment the therapeutic efficacy of anti-P-gp Abs may be beneficial for eradicating metastatic MDR SCLC in humans.

Cytolysis of human dendritic cells by autologous lymphokine-activated killer cells: participation of both T cells and NK cells in the killing.

Dendritic cells (DC) play a key role in the initiation of immune response by stimulating the naive T cells. The fate of DC after the initiation of immune response is not clearly understood. Although there are few reports implicating natural killer (NK) cells in the elimination of DC, killing of DC by LAK cells, and specifically by T cells, has not been studied. In this study, we observed that DC, generated from monocytes, in vitro in the presence of granulocyte-macrophage colony-stimulating factor, interleukin-4 (IL-4), and tumor necrosis factor alpha were susceptible to cytolysis by lymphokine-activated killer (LAK) cells induced in the presence of IL-2 and IL-15 but not IL-12 alone. However, LAK cells induced by a combination of IL-12 and suboptimal dose of IL-2 were cytotoxic to DC. When purified lymphocytes were activated with IL-2, the CD8+/CD57- fraction (T-LAK), but not the CD8-/CD57+ fraction (NK-LAK) was cytotoxic to autologous DC. However, when unseparated peripheral blood mononuclear cells were used to generate LAK cells, both T-LAK and NK-LAK fractions showed equal cytotoxicity against autologous DC. Monoclonal antibodies against CD54, CD11a, and CD18 significantly inhibited the cytolysis, indicating that the killing involves the engagement of CD54 with its ligands.

Heterogeneity of multiorgan metastases of human lung cancer cells genetically engineered to produce cytokines and reversal using chimeric monoclonal antibodies in natural killer cell-depleted severe combined immunodeficient mice.

Lung cancer is a major cause of cancer deaths, most of which can be attributed to distant multiorgan metastases. To examine the cellular and molecular mechanisms of lung cancer metastasis to distant organs, we have established novel models of human lung cancer (small cell and non-small cell lung cancer) metastasis in natural killer cell-depleted severe combined immunodeficient (SCID) mice. We investigated whether local production of the cytokines responsible for regulation of macrophage function at tumor growth sites affects the pattern of lung cancer metastasis in distant organs. Several lung cancer cell lines were genetically engineered to produce human macrophage colony-stimulating factor (M-CSF) and monocyte chemoattractant protein-1 (MCP-1), and their metastatic potentials were assessed. Interestingly, M-CSF gene transduction had an antimetastatic effect for the liver and lymph nodes, but not the kidneys. In contrast, MCP-1 gene-modified lung cancer cells and their parent cells had identical metastatic potentials. These findings indicate a possible role for cytokines and suggest that lung cancer has metastatic heterogeneity. Examining ways of controlling human lung cancer metastases, we investigated the antimetastatic effect of chimeric monoclonal antibodies (MAbs) against P-glycoprotein and ganglioside GM2 (MH162 and KM966, respectively). Both MAbs, when given on days 2 and 7, inhibited the development of distant metastases of lung cancer in a dose-dependent fashion. Combined use of anti-P-glycoprotein MAb with M-CSF or MCP-1 gene transduction caused complete inhibition of metastasis of H69/VP cells. The antimetastatic effect of these MAbs in vivo was mainly due to an antibody-dependent cell-mediated cytotoxicity reaction mediated by mouse macrophages. These findings suggest that the mouse-human chimeric MAb in combination with cytokine gene transduction may be useful for the eradication of lung cancer metastases in humans.

Differential effect of interleukin 10 on interleukin 12- and interleukin 2-mediated killer induction from blood mononuclear cells.

We investigated the regulatory effect of interleukin (IL) 10 on IL-12-inducible killer activity of blood mononuclear cells (MNC) of healthy subjects. IL-10 suppressed non-MHC-restricted killer activity induced by IL-12 in a dose-dependent manner. Cytotoxicity against Daudi cells of blood MNC activated with optimal dose (100 U/ml) of IL-12 was significantly suppressed from 36.6 +/- 6.8% (mean +/- SE) to 26.0 +/- 5.0% by 100 ng/ml of IL-10 (n = 5; P < 0.05) at an E/T ratio of 20. IL-10, however, did not suppress killer induction by IL-2 from blood MNC. On the other hand, IL-4, a known inhibitor of IL-2-mediated killer induction, had no effect on IL-12-mediated killer induction from blood MNC. Moreover, production of interferon-gamma by IL-12-stimulated MNC was suppressed by IL-10. Because the presence of IL-10 is reported in the tumor-growing site, these observations suggest that IL-10 acts as a key cytokine in the suppression of IL-12-mediated antitumor response in situ.

Circumvention of multidrug resistance by a quinoline derivative, MS-209, in multidrug-resistant human small-cell lung cancer cells and its synergistic interaction with cyclosporin A or verapamil.

PURPOSE AND METHODS: To develop a clinically useful approach to circumvent P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) in MDR human small-cell lung cancer (SCLC), we examined the ability of a novel quinoline compound, MS-209, to reverse MDR by inhibition of P-gp function in combination with other MDR-reversing drugs using a cytotoxicity assay. RESULTS: We established MDR human SCLC cells by culture in medium with gradually increasing concentrations of adriamycin (ADM). Compared with the parental human SCLC cells, SBC-3, the MDR variant SBC-3 cells obtained (SBC-3/ADM) were highly resistant to various chemotherapeutic agents due to P-gp expression. MS-209 reversed the resistance to ADM and vincristine (VCR) of SBC-3/ADM and H69/VP cells in a dose-dependent manner. Moreover, MS-209 in combination with cyclosporin A (CsA) or verapamil (VER) synergistically enhanced the antitumor effects of ADM and VCR on SBC-3/ADM cells. MS-209 restored ADM incorporation and this effect was enhanced by CsA and VER, suggesting that these synergistic effects were due to competitive inhibition of P-gp function. CONCLUSION: MS-209 in combination with CsA or VER might increase the efficacy of these chemotherapeutic agents against MDR human SCLC cells.

Therapeutic efficacy of mouse-human chimeric anti-ganglioside GM2 monoclonal antibody against multiple organ micrometastases of human lung cancer in NK cell-depleted SCID mice.

The development of distant metastases to multiple organs is a critical problem in the treatment of human lung cancer. In this study, we evaluated the therapeutic efficacy of a mouse-human chimeric anti-ganglioside GM2 (GM2) monoclonal antibody (MAb), KM966 against metastasis formation of GM2-positive human lung cancer cells inoculated intravenously (i.v.) into natural killer (NK) cell-depleted severe combined immunodeficient (SCID) mice. GM2-positive human small cell lung cancer (SCLC), SBC-3 cells (1 x 10(6)), injected through a tail vein into NK cell-depleted SCID mice, formed large number of metastatic colonies in the liver, kidneys and lymph nodes by 42 days after inoculation (day 42). KM966, but not control MAb, given on days 2 and 7, almost completely inhibited metastasis formation of SBC-3 cells in the liver, kidneys and lymph nodes in a dose-dependent fashion. Moreover, treatment with KM966 at advanced stages of metastasis (even from day 28) significantly suppressed multiple organ metastases of SBC-3 cells. The anti-metastatic effect of KM966 in vivo was mainly due to an antibody-dependent cell-mediated cytotoxicity (ADCC) reaction mediated by macrophages of the SCID mice. Our findings suggest that the mouse-human chimeric anti-GM2 MAb, KM966 may be useful for eradicating multiple organ micrometastases of lung cancer in humans.

The role of cyclosporin A on antibody-dependent monocyte-mediated cytotoxicity against human multidrug-resistant cancer cells.

A P-glycoprotein (P-gp) inhibitor, cyclosporin A (CsA) was found to enhance the susceptibility of multidrug resistant (MDR) cancer cells to anti-P-gp antibody-dependent cellular cytolysis (ADCC) by monocytes, but the exact mechanism is unknown. In this study, we examined whether CsA enhanced the susceptibility of MDR cells through its inhibitory effect of P-gp function by using anti-ganglioside GM2 (GM2) monoclonal antibody (Ab), KM966, instead of anti-P-gp Ab, MRK16. Monocyte-ADCC induced by both KM966 and MRK16 against P-gp positive human MDR ovarian cancer cells was significantly augmented by addition of CsA. KM966, but not MRK16, induced monocyte-ADCC against P-gp negative human ovarian cancer cells and CsA enhanced this ADCC activity, indicating that suppressive effect of P-gp function by CsA was not essential to the enhancement of ADCC. Moreover, pretreatment of tumor cells with CsA augmented their susceptibility to monocyte-ADCC irrespective of P-gp expression. Interestingly, KM966 or MRK16 induced monocyte-ADCC against various human lung cancer cells expressing either GM2 or P-gp, but CsA did not affect these ADCC. These findings suggest that CsA may enhance the susceptibility to the monocyte-ADCC of ovarian cancer cells, but not of lung cancer cells, irrespective of its suppressive effect of P-gp function.

Effect of clarythromycin on the distant metastases of human lung cancer cells in SCID mice.

Recently, the use of macrolides is suggested to be therapeutically effective in prolonging the survival of patients with inoperable non-small cell lung cancer. The purpose of this study was to examine therapeutic effects of a macrolide, clarythromycin (CAM) on the metastastic developments of two different human non-small cell lung cancers (squamous cell lung carcinoma RERF-LC-AI, and adenocarcinoma PC-14) in severe combined immunodeficient (SCID) mice depleted or undepleted of natural killer (NK) cells, respectively. CAM, injected subcutaneously at doses of 5 and 10 mg/kg body weight/day from day 7 to 41 after i.v. inoculation of human lung cancer cells, was not effective in inhibiting their distant organ metastases in SCID mice. CAM at concentrations of less than 10 micrograms/ml did not have a direct influence on the proliferation of these tumor cells in vitro. Although CAM alone was not effective in augmenting NK activity, it augmented the IL-2-induced killer (LAK) activity against Daudi cells in vitro. These results suggest that CAM alone may not be enough to control the spread of non-small cell lung cancer in the patient with T cell dysfunction.

Intrapleural instillation of interferon gamma in patients with malignant pleurisy due to lung cancer.

The effect of intrapleural instillation of recombinant human interferon gamma (IFN gamma) at increasing doses of (1-12) x 10(6) U was examined in six patients with cytologically positive pleural effusion due to lung cancer. Intrapleural instillation was repeated up to three times. Clinically, no reaccumulation of pleural effusion was observed in one patient and disappearance of lung cancer cells from the pleural effusion was seen in two other patients. No severe side-effects were observed. Considerable levels of IFN gamma remained in the pleural effusion as well as in patients' serum up to 7 days after instillation of 2 x 10(6) U and higher doses. The total cell number showed a transient decrease on day 1 of therapy. Levels of pro-inflammatory cytokines, such as tumor necrosis factor alpha, interleukin(IL)-1 beta and IL-6, in the pleural effusion remained almost stable after IFN gamma instillation. On the other hand, intrapleural IL-1 receptor antagonist levels were remarkably elevated by the instillation of IFN gamma. IL-2- and IL-12-inducible killer activity of pleural mononuclear cells tended to increase slightly. Despite the inability of IFN gamma to control pleural effusion in this treatment schedule, IFN gamma instilled by an intrapleural route had a potential local antitumor activity. Moreover, since IFN gamma persists in pleural effusions for a long time after a single instillation, such a therapy in combination with other fibrogenic biological response modifiers can be promising.

Model of malignant pleural effusion of human lung adenocarcinoma in SCID mice.

Malignant pleural effusion (PE) is a frequent problem in lung cancer. In this study, we established a model of malignant PE of human adenocarcinoma cells, PC-14, in SCID mice. Intravenously injected PC-14 cells formed colonies in the lungs as early as week 4 after tumor inoculation, and produced bloody PE in all recipient SCID mice by week 8. Pretreatment of SCID mice with anti-mouse IL-2 receptor beta chain antibody (TM-beta 1) to deplete natural killer (NK) cells markedly promoted the production of bloody PE and metastases to multiple organs, such as the lungs, liver, kidneys, and lymph nodes 4 weeks after tumor inoculation. Histological studies indicated that PC-14 cells formed colonies in the lungs, and then invaded the pleura and spread to the pleural cavity. To establish cell lines with a high potential to produce PE, we harvested PE, expanded the tumor cells in vitro, and injected them into SCID mice again. By four in vivo selection cycles in this way we obtained PC-14-PM4 cells, which produce lung metastases and PE earlier than PC-14 cells. The survival of SCID mice inoculated with PC-14-PM4 cells was significantly shorter than that of mice inoculated with PC-14 cells. The expressions of adhesion molecules, such as CD44, CD49d, ICAM-1, and MHC class I, on PC-14-PM4 cells tended to increase compared with PC-14 cells. These changes of adhesion molecules seem to be one of possible mechanisms involved in higher metastatic potential of PC-14-PM4 cells. PE models with PC-14 and PC-14-PM4 cells should be useful for biological and preclinical studies on malignant PE produced by human lung cancer.