Tumor-specific Cytotoxic Activity Research Articles

Durvalumab Combined with Immunomodulatory Drugs (IMiD) Overcomes Suppression of Antitumor Responses due to IMiD-induced PD-L1 Upregulation on Myeloma Cells.

We previously showed that the interaction of programmed death-ligand 1 (PD-L1) on multiple myeloma (MM) cells with PD-1 not only inhibits tumor-specific cytotoxic T-lymphocyte activity via the PD-1 signaling pathway but also induces drug resistance via PD-L1-mediated reverse signals. We here examined the regulation of PD-L1 expression by immunomodulatory drugs (IMiDs) and antimyeloma effects of the anti-PD-L1 antibody durvalumab in combination with IMiDs. IMiDs induced PD-L1 expression on IMiD-insensitive MM cells and plasma cells from patients newly diagnosed with MM. Gene-expression profiling analysis demonstrated that not only PD-L1, but also a proliferation-inducing ligand (APRIL), was enhanced by IMiDs. PD-L1 induction by IMiDs was suppressed by using the APRIL inhibitor recombinant B-cell maturation antigen (BCMA)-Ig, the antibody against BCMA, or an MEK/ERK inhibitor in in vitro and in vivo assays. In addition, its induction was abrogated in cereblon (CRBN)-knockdown MM cells, whereas PD-L1 expression was increased and strongly induced by IMiDs in Ikaros-knockdown cells. These results demonstrated that PD-L1 upregulation by IMiDs on IMiD-insensitive MM cells was induced by (i) the BCMA-APRIL pathway via IMiD-mediated induction of APRIL and (ii) Ikaros degradation mediated by CRBN, which plays a role in inhibiting PD-L1 expression. Furthermore, T-cell inhibition induced by PD-L1-upregulated cells was effectively recovered after combination treatment with durvalumab and IMiDs. PD-L1 upregulation by IMiDs on MM cells might promote aggressive myeloma behaviors and immune escape in the bone marrow microenvironment.

Anti-inflammatory potential of Patrineolignan B isolated from Patrinia scabra in LPS-stimulated macrophages via inhibition of NF-κB, AP-1, and JAK/STAT pathways

Patrineolignan B (PB), a lignan compound isolated from the radix and rhizomes of Patrinia scabra, was previously reported to possess a strong tumor-specific cytotoxic activity and beneficial effects on nitric oxide (NO) levels in macrophages induced by lipopolysaccharide (LPS). In this study, we assessed the effects of PB on LPS-induced inflammation in RAW 264.7 cells and clarified its molecular mechanisms. PB reversed LPS-induced increase in NO levels and prostaglandin E2 (PGE2) production, as well as inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) protein and mRNA levels in macrophages. Besides, PB prevented the secretion of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 in a concentration-dependent manner. The regulatory effects of PB on LPS-induced inflammatory mediators and overproduction of pro-inflammatory cytokines were shown to depend partly on the suppression of nuclear factor kappa B (NF-κB)-mediated transcription and AP-1 activation regulated by a c-Jun amino-terminal kinase (JNK) and extracellular signal-regulated kinases (ERK). Its anti-inflammatory activity was also mediated by regulating the phosphorylation of Janus kinase (JAK)/signal transducers and activators of transcription 1/3 (STAT1/3) signaling pathway. Taken together, our results suggest that PB exhibits anti-inflammatory potency through interfering with the NF-κB, AP-1, and JAK/STAT signaling pathway in LPS-stimulated macrophages.

PL 04.02 Where We Are Now, and Where We Will Be in 10 years: From Asian Perspective

PL 04.02 Where We Are Now, and Where We Will Be in 10 years: From Asian Perspective

HSP70 Inhibition Limits FAK-Dependent Invasion and Enhances the Response to Melanoma Treatment with BRAF Inhibitors.

The stress-inducible chaperone protein HSP70 (HSPA1) is implicated in melanoma development, and HSP70 inhibitors exert tumor-specific cytotoxic activity in cancer. In this study, we documented that a significant proportion of melanoma tumors express high levels of HSP70, particularly at advanced stages, and that phospho-FAK (PTK2) and BRAF are HSP70 client proteins. Treatment of melanoma cells with HSP70 inhibitors decreased levels of phospho-FAK along with impaired migration, invasion, and metastasis in vitro and in vivo Moreover, the HSP70 inhibitor PET-16 reduced levels of mutant BRAF, synergized with the BRAF inhibitor PLX4032 in vitro, and enhanced the durability of response to BRAF inhibition in vivo Collectively, these findings provide strong support for HSP70 inhibition as a therapeutic strategy in melanoma, especially as an adjuvant approach for overcoming the resistance to BRAF inhibitors frequently observed in melanoma patients. Cancer Res; 76(9); 2720-30. ©2016 AACR.

Metronomic Doses of Temozolomide Enhance the Efficacy of Carbon Nanotube CpG Immunotherapy in an Invasive Glioma Model.

Even when treated with aggressive current therapies, most patients with glioblastoma survive less than two years. Rapid tumor growth, an invasive nature, and the blood-brain barrier, which limits the penetration of large molecules into the brain, all contribute to the poor tumor response associated with conventional therapies. Immunotherapy has emerged as a therapeutic approach that may overcome these challenges. We recently reported that single-walled carbon nanotubes (SWCNTs) can be used to dramatically increase the immunotherapeutic efficacy of CpG oligonucleotides in a mouse model of glioma. Following implantation in the mouse brain, the tumor cell line used in these previous studies (GL261) tends to form a spherical tumor with limited invasion into healthy brain. In order to evaluate SWCNT/CpG therapy under more clinically-relevant conditions, here we report the treatment of a more invasive mouse glioma model (K-Luc) that better recapitulates human disease. In addition, a CpG sequence previously tested in humans was used to formulate the SWCNT/CpG which was combined with temozolomide, the standard of care chemotherapy for glioblastoma patients. We found that, following two intracranial administrations, SWCNT/CpG is well-tolerated and improves the survival of mice bearing invasive gliomas. Interestingly, the efficacy of SWCNT/CpG was enhanced when combined with temozolomide. This enhanced anti-tumor efficacy was correlated to an increase of tumor-specific cytotoxic activity in splenocytes. These results reinforce the emerging understanding that immunotherapy can be enhanced by combining it with chemotherapy and support the continued development of SWCNT/CpG.

Prophylactic Antitumor Effect of Mixed Heat Shock Proteins/Peptides in Mouse Sarcoma.

Background:To develop a vaccine-based immunotherapy for sarcoma, we evaluated a mixture of heat shock proteins (mHSPs) as a vaccine for sarcoma treatment in a mouse model. Heat shock protein/peptides (HSP/Ps) are autoimmune factors that can induce both adaptive and innate immune responses; HSP/Ps isolated from tumors can induce antitumor immune activity when used as vaccines.Methods:In this study, we evaluated the effects of mHSP/Ps on prophylactic antitumor immunity. We extracted mHSP/Ps, including HSP60, HSP70, GP96, and HSP110, from the mouse sarcoma cell lines S180 and MCA207 using chromatography. The immunity induced by mHSP/Ps was assessed using flow cytometry, ELISPOT, lactate dehydrogenase release, and enzyme-linked immunosorbent assay.Results:Of S180 sarcoma-bearing mice immunized with mHSP/Ps isolated from S180 cells, 41.2% showed tumor regression and long-term survival, with a tumor growth inhibition rate of 82.3% at 30 days. Of MCA207 sarcoma-bearing mice immunized with mHSP/Ps isolated from MCA207 cells, 50% showed tumor regression and long-term survival with a tumor growth inhibition rate of 79.3%. All control mice died within 40 days. The proportions of natural killer cells, CD8+, and interferon-γ-secreting cells and tumor-specific cytotoxic T-lymphocyte activity were increased in the immunized group.Conclusions:Vaccination with a polyvalent mHSP/P cancer vaccine can induce an immunological response and a marked antitumor response to autologous tumors. This mHSP/P vaccine exerted greater antitumor effects than did HSP70, HSP60, or tumor lysates alone.

Abstract 2517: Effects of toll-like receptor 4 agonist on the anti-tumor immune response to the GVAX vaccine

Abstract We evaluated the immune response elicited by co-administration of a novel toll-like receptor 4 agonist, glucopyranosyl lipid A (GLA), with a genetically modified tumor cell based vaccine (GVAX) in mice. We have previously reported that the addition of GLA to the GVAX vaccine in mice resulted in a paradoxical decrease in delivery of tumor antigen to the draining lymph node, yet an increase in therapeutic benefit. The addition of GLA to GVAX altered the distribution of the vaccine induced anti-tumor T cell response. In mice vaccinated with GVAX + GLA adjuvant tumor-specific T cells accumulated in the spleen, liver and footpad as soon as two days following vaccination. In contrast, in mice vaccinated with GVAX alone, tumor-specific T cells accumulated primarily only in the dLN. Since our previous study established that incorporation of GLA into the GVAX vaccine did not alter the magnitude of the anti-tumor T cell response, we set out to determine if the co-administration of GLA with GVAX altered the functional capabilities of the anti-tumor T cell response. We found that GLA did not increase in vivo tumor-specific cytotoxic activity or increase the number of anti-tumor interferon-γ expressing T cells found in the tumor or spleen following vaccination. We next determined if the addition of GLA to GVAX altered the kinetics of the anti-tumor T cell response. We found that the addition of GLA to the GVAX vaccine resulted in rapid accumulation of activated anti-tumor T cells in the spleen. Our results suggest that addition of GLA to the GVAX vaccine does not increase the magnitude or significantly improve functional capabilities of the anti-tumor immune response. These findings are consistent with the hypothesis that the addition of GLA to the GVAX vaccine increases therapeutic benefit by altering the distribution of the response, resulting in a more systemic anti-tumor immune response. Citation Format: Michael J. Korrer, Jeff W.m. Bulte, Hyam I. Levitsky. Effects of toll-like receptor 4 agonist on the anti-tumor immune response to the GVAX vaccine. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2517. doi:10.1158/1538-7445.AM2015-2517

Thyroid status modulates the in vivo antitumor response to T lymphoma cells (P2079)

Abstract We have previously observed the regulation of immunity by thyroid status but little is known on how the levels of thyroid hormones (THs) influence antitumor responses. Our aim was to evaluate the antitumor immune response in hyper- and hypothyroid C57BL/6 mice (Hyper and Hypo respectively) which develop solid tumors and metastases in response to inoculation with EL-4 T lymphoma. Hyper showed increased rate of tumor growth compared to Hypo and control mice (C), while Hypo showed more metastases than other groups. Hyper Solid tumors had increased expression of cyclin D1, D3, E1, while Hypo had higher levels of cell cycle inhibitors p27, p16 and p53. At day 10th after EL-4 cell inoculation, when differences in tumor growth were significant, Hyper displayed higher number of cells in lymph nodes and spleens, a lower percentage (%) of myeloid-derived suppressor cells and an increased % of NK cells in the spleen accompanied by an augmented NK cell cytotoxic activity. On the other hand, Hypo displayed a reduction of CD8+ T cells and a decrease in tumor-specific cytotoxic activity. However, there were no differences among the groups in the % of T, B or Treg cells in secondary lymphoid organs. Our results suggest that THs modulate tumor growth through mechanisms involving regulation of proteins related to the progression and/or arrest of the cell cycle, and through the control of the anti-tumor immune response that could limit tumor dissemination.

Apoptin induces apoptosis in nude mice allograft model of human bladder cancer by altering multiple bladder tumor-associated gene expression profiles

Bladder cancer (BC) is one of the most common human malignancies that account for major death in the world. Apoptin that is derived from chicken anemia virus (CAV) has displayed tumor-specific cytotoxic activity in a variety of human carcinomas. However, the magical function of apoptin in bladder carcinoma cell lines has not been identified yet. In our study, we delivered apoptin into bladder-originating T24, EJ, and HCV29 cell lines by adenovirus system. The selective cytotoxic effect of apoptin was determined by cell viability assay, active caspase-3 measurement, and annexin V/PI double staining. Importantly, we have examined the differential expression patterns of tumor-associated genes including Ki67, C-erbB-2, Rb, and nm23 by flow cytometry and western blot in vitro. In an animal study, apoptin was infused into animal models by AAV system, and immunohistochemistry and quantitative real-time PCR (qRT-PCR) were employed to validate results in vivo. The results indicated that apoptin could selectively induce apoptosis in bladder tumorigenic cells coupled with tumor-specific nucleus accumulation in vitro. Interestingly, apoptin could downregulate expression levels of Ki67 and C-erbB-2 and upregulate the expression of Rb both in vitro and in vivo. Moreover, the animal models treated with AAV-apoptin have shown smaller tumor volumes and displayed better prognosis than controls. In conclusion, apoptin could selectively induce apoptosis in bladder tumor cells through altering expression profiles of tumor-associated genes.

Naturally occurring, tumor-specific, therapeutic proteins

The emerging approach to cancer treatment known as targeted therapies offers hope in improving the treatment of therapy-resistant cancers. Recent understanding of the molecular pathogenesis of cancer has led to the development of targeted novel drugs such as monoclonal antibodies, small molecule inhibitors, mimetics, antisense and small interference RNA-based strategies, among others. These compounds act on specific targets that are believed to contribute to the development and progression of cancers and resistance of tumors to conventional therapies. Delivered individually or combined with chemo- and/or radiotherapy, such novel drugs have produced significant responses in certain types of cancer. Among the most successful novel compounds are those which target tyrosine kinases (imatinib, trastuzumab, sinutinib, cetuximab). However, these compounds can cause severe side-effects as they inhibit pathways such as epidermal growth factor receptor (EGFR) or platelet-derived growth factor receptor, which are also important for normal functions in non-transformed cells. Recently, a number of proteins have been identified which show a remarkable tumor-specific cytotoxic activity. This toxicity is independent of tumor type or specific genetic changes such as p53, pRB or EGFR aberrations. These tumor-specific killer proteins are either derived from common human and animal viruses such as E1A, E4ORF4 and VP3 (apoptin) or of cellular origin, such as TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) and MDA-7 (melanoma differentiation associated-7). This review aims to present a current overview of a selection of these proteins with preferential toxicity among cancer cells and will provide an insight into the possible mechanism of action, tumor specificity and their potential as novel tumor-specific cancer therapeutics.

TGF-β1 Induces Preferential Rapid Expansion and Persistence of Tumor Antigen-specific CD8+ T Cells for Adoptive Immunotherapy

Adoptive cell transfer of expanded, autologous tumor-infiltrating lymphocytes (TIL) into lymphodepleted melanoma patients can induce the regression of bulky, metastatic disease. To generate the large numbers of T cells needed for infusion, TIL undergo a rapid expansion protocol (REP) in vitro using anti-CD3 antibody, interleukin-2, and irradiated peripheral blood feeder cells that typically results in an approximately 1000-fold expansion over 14 days. However, we have found that the conventional REP (C-REP) often favors the expansion of CD4+ T cells at the expense of tumor antigen-specific CD8+ T cells, which are the most potent cytolytic effector cells. In this study, we demonstrate that addition of transforming growth factor (TGF)-beta1 to the TIL culture at the onset of rapid expansion (T-REP ) maintained the percentage of CD8+ T cells while not inhibiting overall T-cell expansion. Of T cells expanded from different melanoma patient tumors, 13 of 15 TIL demonstrated improved yields and percentages of both CD8+ and MART-1 melanoma antigen-specific T cells after 14 days of expansion in TGF-beta1 compared with the C-REP. This was associated with a marked improvement in the antitumor activity of the resulting bulk TIL culture in terms of interferon-gamma production and melanoma tumor-specific cytotoxic T-lymphocyte activity. In addition, T-REP T cells demonstrated a higher potential for continued expansion in vitro for up to 3 weeks after the expansion compared with C-REP T cells, suggesting that they may also be capable of increased persistence after adoptive cell transfer. Our results suggest that TGF-beta1-expanded TIL have attributes that might predict efficacy superior to that of conventional TIL.

Prevention of Spontaneous Tumor Development in aretTransgenic Mouse Model by Ret Peptide Vaccination with Indoleamine 2,3-Dioxygenase Inhibitor 1-Methyl Tryptophan

The present study investigated an immunotherapeutic strategy for rearranged during transfection proto-oncogene (ret)-associated carcinomas in a transgenic MT/ret 304/B6 mouse model in which spontaneous tumors develop due to overexpression of the ret gene. A Ret peptide vaccine comprising an extracellular fragment of Ret protein and Th1-polarized immunoregulator CpG oligonucleotide (1826) induced strong and specific cellular and humoral immune responses in wild-type C57BL/6 mice, showing that the Ret peptide has a strong immunogenic potential as part of an antitumor vaccine. In MT/ret 304/B6 mice, however, the vaccine was only modestly effective as an inducer of the humoral immune response, and it failed to elicit a T-cell response. An immunohistochemical analysis revealed marked indoleamine 2,3-dioxygenase expression after immunization with Ret peptide vaccine in the lymph nodes and spleens of MT/ret 304/B6 mice. The systemic administration of the potent inhibitor of indoleamine 2,3-dioxygenase 1-methyl tryptophan (1MT) along with Ret vaccine produced a significant increase in tumor-specific cytotoxic activity. A delay in spontaneous tumor development was also observed in the MT/ret 304/B6 mice to which the Ret vaccine and 1MT were administered. These results indicate that an improved Ret vaccine composed of Ret peptide plus CpG oligonucleotide plus 1MT is a potential therapeutic strategy for treatment of ret-associated carcinomas.

Topical CpG Enhances the Response of Murine Malignant Melanoma to Dacarbazine

Malignant melanoma is a potentially fatal skin cancer that is increasing in incidence. Standard chemoimmunotherapy consisting of dacarbazine (DTIC) given with IFN-alpha has had disappointing results. We describe a chemoimmunotherapy protocol for cutaneous melanoma that combines the administration of DTIC with the topical application of CpG oligodinucleotide (ODN). Subcutaneous B16 melanoma tumors in C57BL/6 mice were treated with intraperitoneal injections of DTIC followed by the topical application of CpG-ODN over the tumors. This therapeutic approach abrogated the growth of established tumors and significantly enhanced survival. Topical CpG application was more effective than intratumoral CpG. Cell depletion studies indicated that the antitumor effect was dependent on both CD4(+) and CD8(+) cells but not on natural killer (NK) cells. Tumor-specific cytotoxic T-lymphocyte activity was generated in treated animals and was highest in topically treated animals. Immunohistochemical analysis revealed that DTIC, but not CpG, enhanced tumor cell apoptosis. Further, topical CpG induced an expansion of a B220(+)CD8(+) subset of dendritic cells and a subset of NK1.1(+) CD11c(+) cells within the tumors. By enhancing both tumor cell death and local immune activation, DTIC/topical CpG chemoimmunotherapy induced an effective T-cell-dependent host-immune response against melanoma.

Inhibition of TACE Activity Enhances the Susceptibility of Myeloma Cells to TRAIL.

TNF-related apoptosis-inducing ligand/Apo2 ligand (TRAIL/Apo2L) selectively induces apoptosis in various cancer cells including myeloma (MM) cells. Although TRAIL-mediated immunotherapy is as attractive maneuver against MM because of its tumor-specific cytotoxic activity, the susceptibility of MM cells to TRAIL has been demonstrated to vary among MM cells, which limits clinical applications of TRAIL-mediated immunotherapy. TRAIL is known to bind to 2 different proapoptotic receptors, death receptor 4 (DR4) and DR5. The membrane-bound TRAIL receptors have been reported to be subjected to proteolytic cleavage in melanoma cells in a manner inhibitable by tissue inhibitor of metalloproteinases-3 (TIMP-3), an endogenous inhibitor for TNF-alpha converting enzyme (TACE) (Ahonen M, Oncogene. 2003). Although TACE is regarded as a sheddase for TNF-like ligands/receptors, the role for TACE in TRAIL-mediated cytotoxicity in MM cells is largely unknown. In the present study, we therefore investigated the role for TACE in TRAIL and its receptor editing as well as the effect of TACE inhibition on TRAIL-triggered cytotoxicity in MM cells. MM cells constitutively expressed DR4 on their surface as determined in flow cytometry, while the expression of DR5 as well as TRAIL was negligible. TACE mRNA was constitutively overexpressed in all MM cell lines including RPMI8226, MM.1S, KMS12 and U266, whereas its endogenous inhibitor, TIMP-3, was not detected, suggesting enhanced TACE activity along with down-regulation of TIMP-3 in MM cells. TAPI-0, a TACE inhibitor, up-regulated the cell-surface expression of DR4 about 2-fold in RPMI8226 and U266 cells, while DR5 and TRAIL expression remained undetectable. Immunoblot analyses for DR4 revealed that conditioned media from RPMI8226 and U266 cells contained DR4 protein with a molecular size smaller than that observed in their cell lysates. Interestingly, TAPI-0 treatment down-regulated DR4 levels in culture supernatants of these MM cells, while increasing DR4 levels in their cell lysates as well as on their surface, suggesting ectodomain shedding of DR4 by TACE in MM cells. Importantly, TAPI-0 treatment potentiated TRAIL-triggered cytotoxicity against MM cells including RPMI8226 and MM.1S, which was almost completely antagonized by addition of osteoprotegerin, a soluble inhibitor for TRAIL, indicating a TRAIL-dependent mechanism. Taken together, the present observations demonstrate that cell-surface TRAIL receptor expression is post-transcriptionally down-regulated by endogenous TACE activity enhanced in MM cells, which may protect MM cells from TRAIL-mediated apoptosis by surrounding immune cells expressing TRAIL, and that up-regulation of TRAIL receptor expression by inhibiting TACE activity is able to restore the susceptibility of MM cells to TRAIL. Therefore, these preclinical data provide that TACE inhibitors in combination with TRAIL-based immunotherapy may be a novel therapeutic approach against MM which can not be cured by the present chemotherapeutic modalities.

Convallasaponin A, a New 5β‐Spirostanol Triglycoside from the Rhizomes of Convallaria majalis.

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Convallasaponin A, a New 5.BETA.-Spirostanol Triglycoside from the Rhizomes of Convallaria majalis

The rhizomes of Convallaria majalis have been analyzed for their steroidal glycoside constituents, resulting in the isolation of a new 5beta-spirostanol triglycoside, named convallasaponin A, along with two known cardenolide glycosides and a known cholestane glycoside. The structure of convallasaponin A was determined on the basis of extensive spectroscopic analysis, including 2D NMR data, and the results of hydrolytic cleavage. The cardenolide glycosides showed tumor specific cytotoxic activity.

Biological activity of carotenoids in red paprika, Valencia orange and Golden delicious apple

Carotenoid fractions were extracted from red paprika, Valencia orange peel and the peel of Golden delicious apple. Thus, hypophasic carotenoids of paprika (PM1), orange (PM3) and apple (PM4), and epiphasic extractions of paprika (PM2) and apple (PM5) were obtained by extraction, saponification and partition between MeOH-H(2)O (9:1) (hypophasic) and hexane (epiphasic). A high content of capsanthin was quantified in hypophasic carotenoids (PM1) from red spice paprika, whereas the hypophasic fractions from orange (PM3) and apple (PM4) were mainly composed of violaxanthin, zeaxanthin and lutein. On the other hand, a high content of beta,beta-carotene and beta-cryptoxanthin was found in epiphasic fractions (PM2 and PM5). The extracts were studied for their anti-Helicobacter pylori (H. pylori), anti-human immunodeficiency virus (HIV), cytotoxic, multidrug resistance (MDR) reversal and radical scavenging activity. Among five PM extracts and beta,betacarotene, PM4 showed potent anti-H. pylori activity (MIC(50) = 36 microg/mL), comparable to metronidazole (MIC(50) = 45 microg/mL). The extracts were inactive against HIV. PM3 and PM4 showed slightly higher cytotoxic activity against three human tumor cell lines (squamous cell carcinoma HSC-2, HSC-3, submandibular gland carcinoma HSG) and human promyelocytic leukemic HL-60 cells than against three normal human oral cells (gingival fibroblast HGF, pulp cell HPC, periodontal ligament fibroblast HPLF), suggesting a tumor-specific cytotoxic activity. PM1, PM3 and PM4 displayed much higher MDR-reversing activity than (+/-)-verapamil. ESR spectroscopy demonstrated that PM1-5 and beta,beta-carotene produced little or no detectable radical under alkaline conditions and did not scavenge the O(2) (-) produced by the hypoxanthine and xanthine oxidase reaction. On the other hand, PM1 and PM2 scavenged efficiently 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, whereas singlet oxygen was also quenched efficiently by PM5 and PM2. The data suggest the potential importance of carotenoids as possible anti-H. pylori and MDR reversal agents. The active principles in the carotenoid extract might differ, depending upon the types of fruits and vegetables.

Biological activity of barbados cherry (acerola fruits, fruit of Malpighia emarginata DC) extracts and fractions.

Fractionation of barbados cherry (acerola fruit, a fruit of Malpighia emarginata DC.) extracts were performed by organic solvent extractions and column chromatographies, using two extraction methods. Higher cytotoxic activity was concentrated in fractions A4 and A6 (acetone extract), and H3 and HE3 (hexane extract). These four fractions showed higher cytotoxic activity against tumor cell lines such as human oral squamous cell carcinoma (HSC-2) and human submandibular gland carcinoma (HSG), when compared with that against normal cells such as human periodontal ligament fibroblasts (HPLF) and human gingival fibroblasts (HGF). HE2 (hexane extract), AE2 (ethyl acetate extract), AE3, AE4, AE5, A8, A9 and A10 showed some relatively higher anti-bacterial activity on the Gram-positive Staphylococcus epidermidis ATCC 1228 but were ineffective on the representative Gram-negative species E. coli and Ps. aeruginosa. The fractions were inactive against Helicobacter pylori, two representative Candida species, and human immunodeficiency virus (HIV). H3, H4 and HE3, which displayed higher tumor-specific cytotoxicity also showed higher multidrug resistance (MDR) reversal activity, than (+/-)-verapamil as positive control. ESR spectroscopy shows that the radical-mediated oxidation is not involved in the induction of tumor-specific cytotoxic activity. The tumor specific cytotoxic activity and MDR reversal activity of barbados cherry may suggest its possible application for cancer therapy.

Cytotoxic and multidrug resistance reversal activity of a vegetable, 'Anastasia Red', a variety of sweet pepper.

The vegetable, Anastasia Red, Capsicum annuum L. var. angulosum Mill. (Solanaceae) was successively extracted with hexane, acetone, methanol and 70% methanol, and the extracts were further separated into a total of 21 fractions by silica gel or octadecylsilane (ODS) column chromatography. The biological activities of extracts and fractions were determined. These extracts showed relatively higher cytotoxic activity against two human oral tumor cell lines (HSC-2, HSG) than against normal human gingival fibroblasts (HGF), suggesting a tumor-specific cytotoxic activity. The cytotoxic activity of these extracts was enhanced by fractionation on silica gel [H2, A2, M1-M3] or ODS column chromatography [70M]. Several fractions [H2, H4, H5, A1, A2, A3, A5, A6, A7, M2] reversed the multidrug resistance (MDR) phenotype with L5178 mouse lymphoma T cells, more efficiently than (+/-)-verapamil. The extracts and fractions did not show any detectable anti-human immunodeficiency virus (HIV) or anti-Helicobacter pylori activity. Thus, this study suggests the effective and selective antitumor potential of 'Anastasia Red' of sweet pepper for further phytochemical and biological investigation.

Interleukin-12-mediated induction of systemic immunity in the periphery and recruitment of activated T cells into the brain produce limited antitumor effects compared with interleukin-2

Interleukin-12 (IL-12) stimulates the type 1 helper T (Th1) cell responses and augments antitumor immunity. We examined possible antitumor effects of IL-12 secreted intracerebrally (i.c.) and/or subcutaneously (s.c.) in an experimental glioblastoma model and compared the effects with those of IL-2. Rat 9L gliosarcoma cells retrovirally transduced with the IL-12 or IL-2 gene (9L/IL-12 and 9L/IL-2, respectively) were completely rejected when they were s.c. inoculated. The transduced cells, implanted i.c., developed progressive brain tumors at reduced rates compared with 9L brain tumors and the growth retardation of 9L/IL-2 tumors was greater than that of 9L/IL-12 tumors. When rats were s.c. immunized with either 9L/IL-12 or 9L/IL-2 cells, the growth of 9L brain tumors developed in the rats was suppressed compared with that of 9L tumors in naive rats. Among various combinations of simultaneous inoculations of cytokine producers s.c. and i.c., 9L/IL-2 but not 9L/IL-12 cells inoculated i.c. were rejected when the rats were s.c. immunized with either 9L/IL-12 or 9L/IL-2 cells. The synergistic antitumor effects induced were correlated with the infiltration levels of CD8+ and CD4+ T cells into brain tumors. Tumor-specific cytotoxic activity was induced in the rats immunized s.c. with 9L/IL-2 but not fully in the rats with 9L/IL-12 cells. These results collectively suggest that the antitumor activity with IL-2 was superior to IL-12 both in the induction of cytotoxic T cells and in the recruitment of activated T cells into brain tumors.