Antitumor activity of platinum analogs against human lung cancer cell lines and tumor specimens

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.

Comparative analysis of interleukin 15 and interleukin 2 for induction of killer activity and of type 2 cytokine production by mononuclear cells from lung cancer patients

Interleukin (IL) 15 is a novel cytokine with IL-2-like activity. In this study, we examined the effect of IL-15 on induction of non major histocompatibility complex (MHC)-restricted killer activity and of type 2 cytokine production by peripheral blood and pleural mononuclear cells (MNCs), from 34 lung cancer patients and 20 control subjects. IL-15 induced significant killer activity in blood MNCs from lung cancer patients as well as control subjects against a small-cell lung cancer cell line (SBC-3). Effective killer induction by IL-15 was observed even in blood MNCs and pleural MNCs from the site of tumour growth in advanced lung cancer patients. IL-12 had an additive effect with a suboptimal dose of IL-15 in induction of killer activity. In the case of MNCs from lung cancer patients, IL-10 production was more prominent when cells were incubated with IL-2 than with IL-15. IL-5 production was observed in MNCs from lung cancer patients stimulated with IL-2, but not with IL-15. These observations suggest that IL-15, by virtue of its lesser induction of type 2 cytokine, may be a better candidate than IL-2 for lung cancer immunotherapy.

Induction by interleukin-15 of human killer cell activity against lung cancer cell lines and its regulatory mechanisms

Interleukin (IL)-15 is a novel cytokine with IL-2-like activity. In the present study, we examined IL-15-mediated induction of killer activity of peripheral blood mononuclear cells (MNC) against lung cancer cell lines, and the regulatory mechanisms of this induction by IL-15. Cytotoxic activity was measured by 51Cr release assay. IL-15 at concentrations of more than 10 ng/ml induced significant killer activity of blood MNC against a small cell lung cancer cell line (SBC-3), as well as Daudi cells, and 50 ng/ml was considered its optimal concentration. A time course study revealed that an incubation period of 4-6 days was optimal for induction of killer activity. MNC cultured with IL-15 also exhibited killer activity against other lung cancer cell lines (H-69, N-291 and PC-9 cells). IL-15 and IL-12 had additive effects on induction of killer activity against SBC-3 cells. On the other hand, IL-15 had no synergistic or additive effect on induction of killer activity by IL-2. Fresh human monocytes isolated by centrifugal elutriation augmented the development of killer activity of lymphocytes stimulated by IL-15. As a humoral regulatory factor, IL-4 had a suppressive effect on induction of killer activity by IL-15. IFN-gamma, IL-1beta, TNF-alpha, IL-6 or IL-10 had no effect on induction of killer activity by IL-15 at the optimal concentration. These results suggest that IL-15 has potential for the immunotherapy of lung cancers.

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 mononuclear 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-gamma] 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.