Genetically engineered humanized anti-ganglioside GM2 antibody against multiple organ metastasis produced by GM2-expressing small-cell lung cancer cells

Small-cell lung cancer (SCLC) grows rapidly and metastasizes to multiple organs. We examined the antimetastatic effects of the humanized anti-ganglioside GM2 (GM2) antibodies, BIW-8962 and KM8927, compared with the chimeric antibody KM966, in a SCID mouse model of multiple organ metastases induced by GM2-expressing SCLC cells. BIW-8962 and KM8927 induced higher antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity than KM966 against the GM2-expressing SCLC cell line SBC-3 in vitro. These humanized antibodies inhibited the production of multiple organ metastases, increased the number of apoptotic cells, and prolonged the survival of the SCID mice. Histological analyses using clinical specimens showed that SCLC cells expressed GM2. These findings suggest that humanized anti-GM2 antibodies could be therapeutically useful for controlling multiple organ metastases of GM2-expressing SCLC.     

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.     

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.     

Effect of a chimeric anti-ganglioside GM2 antibody on ganglioside GM2-expressing human solid tumors in vivo.

Ganglioside GM2 is expressed on the surface of neuroblastoma and glioblastoma cells, and may also be detected on lung cancer cells. We reported previously that anti-ganglioside GM2 antibody exhibited strong in vitro anti-tumor activity against adriamycin-resistant cancer cells, which overexpressed ganglioside GM2. In the present study, we examined the in vivo anti-tumor effect of the chimeric anti-ganglioside GM2 antibody, KM966, against human lung and breast carcinoma cells, SBC-3 and MCF-7, and respective adriamycin-resistant clones, SBC-3/ADM and AdrR MCF-7 in BALB/c nu/nu mice. Ratios of tumor volume (T/C) between KM966-treated group and control group were 0.01 for SBC-3, 0.00 for SBC-3/ADM, 0.85 for MCF-7 and 0.34 for AdrR MCF-7 cells, respectively. Nude mice, which were pretreated with anti-asialo GM1 antibody to remove natural killer cells, were transplanted with 4 x 10(7) of SBC-3 and SBC-3/ADM subcutaneously. Seven days later, when tumors had grown to a diameter of over 8 mm, mice began to receive intravenous treatment of 120 microgram/mouse KM966 daily. Fourteen daily treatments induced regression to less than 4-mm diameter in 4/5 SBC-3 tumors and 5/5 of SBC-3/ADM tumors. All SBC-3/ADM tumors disappeared completely, suggesting that KM966 exerts a strong in vivo anti-tumor effect on ganglioside GM2-expressing cancer cells. In KM966-treated mice, the surface of the tumor cells stained positive with anti-human IgG. In addition, numerous leukocytes had infiltrated into the tumor mass. Antibody-dependent cell-mediated cytotoxicity (ADCC) of KM966 against tumor cells was examined in vitro by (51)Cr-release assay and revealed that KM966 induces ADCC activity against ganglioside GM2-expressing tumors. Our results suggest that immunotherapy using KM966 may be useful for the treatment of ganglioside GM2-expressing solid tumors.     

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.     

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.     

Follistatin suppresses the production of experimental multiple-organ metastasis by small cell lung cancer cells in natural killer cell-depleted SCID mice.

PURPOSE: Follistatin (FST), an inhibitor of activin, regulates a variety of biological functions, including cell proliferation, differentiation, and apoptosis. However, the role of FST in cancer metastasis is still unknown. Previous research established a multiple-organ metastasis model of human small cell lung cancer in natural killer cell-depleted SCID mice. In this model, i.v. inoculated tumor cells produced metastatic colonies in multiple organs including the lung, liver, and bone. The purpose of this study is to determine the role of FST in multiple-organ metastasis using this model. EXPERIMENTAL DESIGN: A human FST gene was transfected into the small cell lung cancer cell lines SBC-3 and SBC-5 and established transfectants secreting biologically active FST. The metastatic potential of the transfectants was evaluated using the metastasis model. RESULTS: FST-gene transfection did not affect the cell proliferation, motility, invasion, or adhesion to endothelial cells in vitro. I.v. inoculated SBC-3 or SBC-5 cells produced metastatic colonies into multiple organs, including the lung, liver, and bone in the natural killer cell-depleted SCID mice. FST transfectants produced significantly fewer metastatic colonies in these organs when compared with their parental cells or vector control clones. Immunohistochemical analyses of the liver metastases revealed that the number of proliferating tumor cells and the tumor-associated microvessel density were significantly less in the lesions produced by FST transfectants. CONCLUSIONS: These results suggest that FST plays a critical role in the production of multiple-organ metastasis, predominantly by inhibiting the angiogenesis. This is the first report to show the role of FST in metastases.     

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.     

Parathyroid hormone-related protein (PTHrP) is responsible for production of bone metastasis, but not visceral metastasis, by human small cell lung cancer SBC-5 cells in natural killer cell-depleted SCID mice

We previously established an osteolytic bone metastasis model with multiorgan dissemination in natural killer (NK) cell-depleted severe combined immunodeficient (SCID) mice using human small cell lung cancer cells (SBC-5), which highly express the parathyroid hormone-related protein (PTHrP). In our present study, we evaluated the role of PTHrP on bone metastasis by SBC-5 cells using anti-PTHrP neutralizing antibody (Ab). Anti-PTHrP Ab did not affect the proliferation or cytokine production of SBC-5 cells in vitro. Repeated intravenous injection with anti-PTHrP Ab inhibited the formation of bone metastasis in a dose-dependent manner, while the same treatment had no significant effect on the metastasis to visceral organs (lung, liver, kidney and lymph node). In addition, treatment with anti-PTHrP Ab improved the elevated serum calcium level, associated with inhibition of osteolytic bone metastasis, suggesting that anti-PTHrP Ab inhibited bone metastasis via suppression of bone resorption probably by neutralizing PTHrP. These findings suggest that PTHrP is essential for bone metastasis, but not visceral metastasis, by small cell lung cancer SBC-5 cells.     

Combined therapy with a new bisphosphonate, minodronate (YM529), and chemotherapy for multiple organ metastases of small cell lung cancer cells in severe combined immunodeficient mice.

PURPOSE: Lung cancer in the advanced stage frequently metastasizes to multiple organs, including the liver, lungs, lymph nodes, and bone. Bisphosphonates have been widely used to treat osteolytic bone metastasis in the past years; however, many studies have implicated that a single use of bisphosphonates could not prolong the survival of patients. In the present study, using a multiple-organ metastasis model of human lung cancer cells, we examined the effect of combined therapy with a new bisphosphonate (YM529) and etoposide (VP-16). EXPERIMENTAL DESIGN: Human small cell lung cancer (SBC-5) cells i.v. inoculated into natural killer cell-depleted severe combined immunodeficient mice metastasized to multiple organs, including the lungs, liver, kidneys, lymph nodes, and bone. SBC-5-bearing mice were treated with YM529 and/or VP-16 and sacrificed 5 weeks after tumor cell inoculation. Bone metastasis was assessed by X-ray photographs, and visceral metastasis was evaluated macroscopically. The number of osteoclasts in the bone lesions was examined by tartrate-resistant acid phosphatase staining. RESULTS: Monotherapy with YM529 suppressed the production of bone metastases, but not visceral metastasis. Histological analyses revealed that the number of osteoclasts in bone lesions was lower in YM526-treated mice, compared with control mice. VP-16 inhibited both bone metastasis and visceral (lung and liver) metastasis. However, neither YM529 alone nor VP-16 alone significantly prolonged the survival of SBC-5-bearing mice. Combined use of YM529 and VP-16 further inhibited the production of bone metastasis and significantly prolonged survival. CONCLUSIONS: Combined therapy with bisphosphonate and chemotherapy may be useful for small cell lung cancer patients with multiple organ metastases including bone metastasis.     

Novel metastasis model of human lung cancer in SCID mice depleted of NK cells

Metastasis is a critical problem in the treatment of human lung cancer. Thus, a suitable animal model of metastasis of human lung cancer is required for in vivo biological and preclinical studies. In this study, we tried to establish a suitable model for this, using SCID mice. Neither human SCLC H69/VP cells (5 × 10⁶) nor squamous-cell carcinoma RERF-LC-AI cells (1 × 10⁶), injected through a tail vein, formed metastases in untreated SCID mice. Pre-treatment of SCID mice with anti-asialo GM₁ serum resulted in only a few metastases of H69/VP cells, but pre-treatment with anti-mouse IL-2 receptor β chain Ab (TM-β1) resulted in numerous lymph-node metastases 56 days after tumor inoculation. H69/VP-M cells, an in vivo-selected variant line, formed significant numbers of lymph-node metastases even in SCID mice pre-treated with anti-asialo GM₁ serum. SCID mice depleted of NK cells by treatment with TM-β1 showed different patterns of metastasis when inoculated intravenously with the 2 different human lung cancer cell lines (H69/VP and RERF-LC-AI cells): H69/VP cells formed metastases mainly in systemic lymph nodes and the liver, whereas RERF-LC-AI cells formed metastases mainly in the liver and kidneys, with only a few in lymph nodes. A histopathological study showed that the metastatic colonies consisted of cancer cells. The numbers of metastatic colonies formed by the 2 cell lines increased with the number of cells inoculated. TM-β1 treatment of SCID mice efficiently removed NK cells from peripheral blood for at least 6 weeks, whereas, after treatment of the mice with anti-asialo GM₁ serum, NK cells were recovered within 9 days. These findings suggest that NK-cell-depleted SCID mice may be useful as a model in biological and pre-clinical studies on metastasis of human lung cancer. © 1996 Wiley-Liss, Inc.     

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.     

Reversal of adriamycin resistance with chimeric anti-ganglioside GM2 antibody

Ganglioside G_M2 is one of the major cell-surface gangliosides expressed in human tumors. We earlier established a mouse/human IgGI chimeric anti-G_M2 antibody, KM966, which displayed anti-tumor activity in human tumor cells both in vitro and in vivo. In this study, we have screened for changes in ganglioside expressions in several drug-resistant human cancer cell lines to examine the modulation of drug resistance by immunotherapy with anti-ganglioside antibodies. Increased G_M2 expression, detected by flow cytometry and thin-layer chromatography, was observed in the SBC-3/ADM and AdrR MCF7 adriamycin-resistant cell lines, in contrast with their parental lines. In other related gangliosides, ganglioside G_D2 levels in AdrR MCF7 were higher than those in MCF7 cells. We confirmed increased N-acetylgalactosaminyltransferase mRNA in adriamycin-resistant cell lines, as compared with the parental cells, by Northern-blot analysis. Moreover, to investigate the possibility of exploiting the anti-tumor activity of KM966 in order to overcome resistance to adriamycin, we investigated the antibody-dependent cell-mediated cytotoxity of human peripheral mononuclear blood cells and the complement-dependent cytotoxity of human serum with KM966 against SBC-3, SBC-3/ADM, MCF7 and AdrR MCF7. Significantly higher killing via KM966 was observed in SBC-3/ADM and AdrR MCF7 cells as compared with the parental cells. This suggests that passive immunotherapy using KM966 against human adriamycin-resistant cancer may be useful for overcoming resistance to adriamycin. © 1996 Wiley-Liss, Inc.     

Anti-ganglioside GM2 Monoclonal Antibody-dependent Killing of Human Lung Cancer Cells by Lymphocytes and Monocytes

Ganglioside GM₂ (GM₂) frequently appears on the cell surface of human cancers of neuroendocrine origin. A mouse-human chimeric monoclonal antibody (mAb), KM966, against GM₂ was previously found to promote the lysis of various cancer cells by human blood mononnclear cells (MNC). In this study, we analyzed the effector cells responsible for the chimeric mAb-dependent cell-mediated cytotoxicity (ADCC) against small cell lung cancer (SCLC) cells and examined the enhancing effect of various cytokines on the ADCC activity. The ADCC activity was assessed by 4-h ⁵¹Cr release assay. Highly purified lymphocytes (>99%) and monocytes (>90%) were separated by centrifugal elutriation from peripheral blood MNC of the same healthy donor. KM966 induced lysis of SCLC cells mediated by both lymphocytes and monocytes to similar extents, in a dose-dependent manner. Pretreatment of lymphocytes with various cytokines [interleukin (IL)-2, IL-12 and interferon-γ] and that of monocytes with macrophage-colony-stimulating factor significantly augmented the killer activity against SCLC cells in the presence of KM966 mAb. KM966 was also effective for the lysis of non-small cell lung cancer cells in direct proportion to the GM₂ expression levels. These findings suggest that combined treatment of KM966 mAb with cytokines may be therapeutically useful for in vivo killing of lung cancer cells expressing GM₂ through the ADCC reaction.     

Organ heterogeneity of host-derived matrix metalloproteinase expression and its involvement in multiple-organ metastasis by lung cancer cell lines

Cancer metastasis is tightly regulated by the interaction of tumor cells and host organ microenvironments. Matrix metalloproteinases (MMPs), produced by both tumor cells and host stromal cells, play a central role in tumor invasion and angiogenesis. We determined whether metastatic potential of lung cancer to multiple organs is dependent solely on the expression of MMPs by tumor cells, using two metastasis models of human lung cancer cell lines expressing various levels of MMPs and a MMP inhibitor (ONO-4817). In the lung metastasis model, tumor cells (PC14, PC14PE6, H226, A549) inoculated i.v. into nude or SCID mice metastasized only in the lung. In the multiple-organ metastasis model, tumor cells (RERF-LC-AI, SBC-3/DOX, H69/VP, which express low levels of MMPs) inoculated i.v. into natural killer cell-depleted SCID mice metastasized into the liver, kidneys, and systemic lymph nodes. Film in situ zymography analysis revealed that the nontumor parenchyma of the lung had no gelatinolytic activity, whereas gelatinolytic activity of the liver and kidney was high and low, respectively. In the lung metastasis model, gelatinolytic activity of lung nodules directly correlated with the in vitro expression of MMP-2 and MMP-9 by tumor cells. Inhibition of MMP activity by ONO-4817 suppressed lung metastasis by the cell lines that expressed MMPs, but not those that did not express MMP, via the inhibition of MMP activity of lung tumors. In the multiple-organ metastasis model, liver parenchyma, but not liver nodules, showed gelatinolytic activity. The MMP inhibition reduced metastasis to the liver, but not to the kidney or lymph nodes, via inhibition of MMP activity of liver parenchyma. These findings suggest that MMP expression varies among the host organ microenvironments and that stromal MMPs may promote metastasis of lung cancer. Therefore, antimetastatic effects based on MMP inhibition may be dependent on MMPs derived not only from tumor cells but also from organ-specific microenvironments.     

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.     

Monocyte chemoattractant protein-1 gene modification of multidrug-resistant human lung cancer enhances antimetastatic effect of therapy with anti-P-glycoprotein antibody in SCID mice

Distant metastases and multidrug resistance are critical problems in the therapy of human small cell lung cancer (SCLC). In this study, we investigated whether transduction of the monocyte chemoattractant protein-1 (MCP-1) gene into multidrug-resistant (MDR) human lung cancer cells affected the formation of metastases or their inhibition by the anti-P-glycoprotein (P-gp) monoclonal antibody (MAb) MRK16. MDR human SCLC (H69/VP) cells were transduced with the human MCP-1 gene inserted into the expression vector BCMGSNeo. MCP-1 gene transduction had no effect on drug sensitivity, the expression of surface antigens or the in vitro proliferation of H69/VP cells. Using the metastatic model of NK cell-depleted SCID mice, H69/VP cells transduced with the MCP-1 gene were inoculated intravenously (i.v.) and formed metastatic colonies in the liver, kidneys and lymph nodes, similar to those formed by parent or mock-transduced cells. However, systemic treatment of the mice with MRK16 reduced the metastases of H69/VP cells in the liver, kidneys and lymph nodes, and was significantly more effective in inhibiting the metastases of MCP-1 producing H69/VP than those of mock-transduced cells. MCP-1 gene transduction significantly prolonged the survival of tumor-bearing mice treated with MRK16. Our findings suggest that local production of MCP-1 in the tumor site increases the anti-P-gp antibody-dependent cell-mediated cytotoxicity, and the MCP-1 gene-induced modification of MDR human SCLC cells thereby enhances the antimetastatic effect of therapy with anti-P-gp antibody. Thus, the accumulation of effector cells in the tumor site is a very important factor in the therapy using the anti-P-gp antibody.     

Molecular pathogenesis and its therapeutic modalities of lung cancer metastasis to bone

Bone metastasis is a critical problem of lung cancer patients. Reproducible animal models of lung cancer bone metastasis, like NK-cell depleted SCID mouse model with SCB-5 cells, are useful to explore the molecular mechanism and search of molecular targets. SBC-5 cells overexpressed PTHrP and that treatment with anti-PTHrP neutralizing antibody inhibited the production of bone metastases of SBC-5 cells in the NK-cell depleted SCID mouse model, indicating the critical role of PTHrP in bone metastasis in this model. In addition, we demonstrated that several compounds, including bisphosphonates and reveromycin A, potentially suppress osteoclast-activity were beneficial for the treatments of bone metastasis. Multi-modality therapy may be necessary for further augmenting the therapeutic efficacy against lung cancer bone metastasis.     

A novel SCID Mouse Model for Studying Spontaneous Metastasis of Human Lung Cancer to Human Tissue

We established a novel severe combined immunodeficient (SCID) mouse model for the study of human lung cancer metastasis to human lung. Implantation of both human fetal and adult lung tissue into mammary fat pads of SCID mice showed a 100% rate of engraftment, but only fetal lung implants revealed normal morphology of human lung tissue. Using these chimeric mice, we analyzed human lung cancer metastasis to both mouse and human lungs by subcutaneous inoculation of human squamous cell carcinoma and adenocarcinoma cell lines into the mice. In 60 to 70% of SCID mice injected with human-lung squamous-cell carcinoma, RERF-LC-AI, cancer cells were found to have metastasized to both mouse lungs and human fetal lung implants but not to human adult lung implants 80 days after cancer inoculation. Furthermore, human-lung adenocarcinoma cells, RERF-LC-KJ, metastasized to the human lung implants within 90 days in about 40% of SCID mice, whereas there were no metastases to the lungs of the mice. These results demonstrate the potential of this model for the in vivo study of human lung cancer metastasis.     

Recombinant antibodies against ganglioside expressed on tumor cells

Several gangliosides such as GM2, GD2, and GD3 have been thought of as target molecules for active or passive immunotherapy of human cancers because of their dominant expression on the tumor cell surface, especially in tumors of neuroectodermal origin. We established a number of mouse or rat monoclonal antibodies (mAbs) to a series of gangliosides to investigate the nature of the molecules on the cell surface. Some of those mAbs were converted to chimeric or humanized mAbs with the aim of developing immunotherapy for human cancer. It is desirable for mAbs to remain on the cell surface for a long time so that they can exert effector functions such as complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC). We found that mAbs to GM2, GD2, and GD3 remain on the cell surface for ₨ min after binding, while mAbs to other types of carbohydrate such as sialy Le^a are quickly internalized. A chimeric mAb to GD3, KM871, was generated by linking cDNA sequences encoding light- and heavy-chain variable regions of mouse mAb KM641 with cDNAs encoding the constant region of human immunoglobulin ų (IgG-1). KM871 bound to a variety of tumor cell lines, especially melanoma cells, including some cell lines to which R24 failed to bind. In a preclinical study, intravenous injection of KM871 markedly suppressed tumor growth and radio-labeled KM871 efficiently targeted the tumor site in a nude mouse model. This chimeric mAb is being evaluated in a phase I clinical trial in melanoma patients. The chimeric mAb KM966 and humanized mAb KM8969 to GM2 originated from a mouse IgM mAb. When human serum and human peripheral blood mononuclear cells were used as effectors in CDC and ADCC, respectively, KM966 and KM8969 killed GM2-expressing tumor cells effectively. In addition, these mAbs may induce apoptosis of a small cell lung cancer cell line cultured under conditions mimicking physiological tumor conditions.