In ovarian cancer maraviroc potentiates the antitumoral activity and further inhibits the formation of a tumor-promoting microenvironment by trabectedin

Ovarian cancer (OC) is the fifth most frequent cause of cancer-related death in women. Chemotherapy agent trabectedin, affecting cancer cells and tumor microenvironment, has been approved for the treatment of relapsed platinum-sensitive OC patients. CCR5-antagonist maraviroc inhibits tumor growth, metastasis, and enhances the antitumoral activity of DNA-damaging drugs. Here, we found that OC cells expressed CCR5 receptor but did not secret CCR5-ligands. Maraviroc treatment did not affect OC cell viability, but strongly potentiated the antiproliferative activity, apoptosis induction, cell cycle blockage, DNA damage, and ROS formation by trabectedin. In A2780cis cisplatin-resistant cells, the cross-resistance to trabectedin was overcame by the combination with maraviroc. Maraviroc enhanced trabectedin cytotoxicity in OC 3Dimensional spheroids and THP-1-monocytes. Both maraviroc and trabectedin interact with drug efflux pump MDR1/P-gp, overexpressed in recurrent OC patients. Maraviroc increased trabectedin intracellular accumulation and the MDR1-inhibitor verapamil, like maraviroc, increased trabectedin cytotoxicity. In OC tumor xenografts the combination with maraviroc further reduced tumor growth, angiogenesis, and monocyte infiltration by trabectedin. In conclusion, this study offers a preclinical rationale for the use of maraviroc as new option to improve trabectedin activity in relapsed chemoresistant OC patients.

Dinuclear gold(I) complexes based on carbene and diphosphane ligands: bis[2-(dicyclohexylphosphano)ethyl]amine complex inhibits the proteasome activity, decreases stem cell markers and spheroid viability in lung cancer cells

Three new dinuclear gold(I) complexes (1-3) containing a carbene (1,3-Bis(2,6-di-isopropylphenyl)imidazol-2-ylidene (IPr)) and diphosphane ligands [bis(1,2-diphenylphosphano)ethane (Dppe), bis(1,3-diphenylphosphano)propane (Dppp) and bis[2-(dicyclohexylphosphano)ethyl]amine (DCyPA)], were synthesized and characterized by elemental analysis and, ESI-MS, mid FT-IR and NMR spectroscopic methods. The structures of complexes 2 and 3 were determined by X-ray crystallography, which revealed that the complexes are dinuclear having gold(I) ions linearly coordinated. The anticancer activities of the complexes (1-3) were evaluated in lung (A549), breast (MC-F7), prostate (PC-3), osteosarcoma (MG-63) and ovarian (A2780 and A2780cis) cancer models. Growth inhibition by the new complexes was higher than cisplatin in all cell lines tested. The mechanism of action of complex 3 was investigated in A549 cells using 2-dimensional (2D) models and 3D-multicellular tumor spheroids. Treatment of A549 cells with complex 3 caused: the induction of apoptosis and the generation of reactive oxygen species; the cell cycle arrest in the G0/G1 phase; the inhibition of both the proteasome and the NF-kB activity; the down-regulation of lung cancer stem cell markers (NOTCH1, CD133, ALDH1 and CD44). Complex 3 was more active than cisplatin also in 3D models of A549 lung cancer cells.

In Doxorubicin-Adapted Hodgkin Lymphoma Cells, Acquiring Multidrug Resistance and Improved Immunosuppressive Abilities, Doxorubicin Activity Was Enhanced by Chloroquine and GW4869

Classical Hodgkin lymphoma (cHL) is a highly curable disease (70-80%), even though long-term toxicities, drug resistance, and predicting clinical responses to therapy are major challenges in cHL treatment. To solve these problems, we characterized two cHL cell lines with acquired resistance to doxorubicin, KM-H2dx and HDLM-2dx (HRSdx), generated from KM-H2 and HDLM-2 cells, respectively. HRSdx cells developed cross-resistance to vinblastine, bendamustin, cisplatin, dacarbazine, gemcitabine, brentuximab vedotin (BV), and γ-radiation. Both HDLM-2 and HDLM-2dx cells had intrinsic resistance to BV but not to the drug MMAE. HDLM-2dx acquired cross-resistance to caelyx. HRSdx cells had in common decreased CD71, CD80, CD54, cyt-ROS, HLA-DR, DDR1, and CD44; increased Bcl-2, CD58, COX2, CD26, CCR5, and invasive capability; increased CCL5, TARC, PGE2, and TGF-β; and the capability of hijacking monocytes. In HRSdx cells less sensitive to DNA damage and oxidative stress, the efflux drug transporters MDR1 and MRP1 were not up-regulated, and doxorubicin accumulated in the cytoplasm rather than in the nucleus. Both the autophagy inhibitor chloroquine and extracellular vesicle (EV) release inhibitor GW4869 enhanced doxorubicin activity and counteracted doxorubicin resistance. In conclusion, this study identifies common modulated antigens in HRSdx cells, the associated cross-resistance patterns, and new potential therapeutic options to enhance doxorubicin activity and overcome resistance.

Current and Emerging Approaches to Study Microenvironmental Interactions and Drug Activity in Classical Hodgkin Lymphoma

Simple Summary

In classical Hodgkin Lymphoma (cHL), the tumor microenvironment (TME) plays an important role in tumor progression and treatment response, making its evaluation critical for determining prognosis, treatment strategies and predicting an increase in drug toxicity. Therefore, there is a need to utilize more complex systems to study the cHL-TME and its interplay with tumor cells. To evaluate new anticancer drugs and to find the mechanisms of drug resistance, this review summarizes emerging approaches for the analysis of the TME composition and to identify the state of the disease; the in vitro techniques used to determine the mechanisms involved in the building of an immunosuppressive and protective TME; new 3-dimensional (3D) models, the heterospheroids (HS), developed to mimic TME interactions. Here, we describe the present and likely future clinical applications indicated by the results of these studies and propose a classification for the in vitro culture methods used to study TME interactions in cHL.

Abstract

Classic Hodgkin lymphoma is characterized by a few tumor cells surrounded by a protective and immunosuppressive tumor microenvironment (TME) composed by a wide variety of noncancerous cells that are an active part of the disease. Therefore, new techniques to study the cHL-TME and new therapeutic strategies targeting specifically tumor cells, reactivating the antitumor immunity, counteracting the protective effects of the TME, were developed. Here, we describe new methods used to study the cell composition, the phenotype, and the spatial distribution of Hodgkin and Reed–Sternberg (HRS) cells and of noncancerous cells in tumor tissues. Moreover, we propose a classification, with increasing complexity, of the in vitro functional studies used to clarify the interactions leading not only to HRS cell survival, growth and drug resistance, but also to the immunosuppressive tumor education of monocytes, T lymphocytes and fibroblasts. This classification also includes new 3-dimensional (3D) models, obtained by cultivating HRS cells in extracellular matrix scaffolds or in sponge scaffolds, under non-adherent conditions with noncancerous cells to form heterospheroids (HS), implanted in developing chick eggs (ovo model). We report results obtained with these approaches and their applications in clinical setting.

In Ovarian Cancer Multicellular Spheroids, Platelet Releasate Promotes Growth, Expansion of ALDH+ and CD133+ Cancer Stem Cells, and Protection against the Cytotoxic Effects of Cisplatin, Carboplatin and Paclitaxel

A high platelet count is associated with a poor prognosis in ovarian cancer (OvCa). Despite good clinical responses with platinating agents in combination with taxanes, numerous OvCa patients relapse due to chemotherapy resistance. Here, we report that treatment of OvCa cells A2780, OVCAR5 and MDAH with releasate from activated platelets (PR) promoted multicellular tumor spheroid (MCTS) formation. These OvCa-MCTSs had increased percentages of CD133+ and aldehyde dehydrogenase (ALDH)+ cells, bona fide markers of OvCa cancer stem cells (CSCs). PR increased OVCAR5- and MDAH-MCTS viability and decreased the cytotoxic and pro-apoptotic effects of paclitaxel, cisplatin and carboplatin. PR increased the volume of spontaneously formed OVCAR8-MCTSs and counteracted their size reduction due to cisplatin, carboplatin and paclitaxel treatment. PR promoted the survival of ALDH+ and CD133+ OvCa cells during cisplatin, carboplatin and paclitaxel treatment. In conclusion, molecules and growth factors released by activated platelets (EGF, PDGF, TGF-β, IGF and CCL5) may protect tumor cells from chemotherapy by promoting the expansion of ALDH+ and CD133+ OvCa-CSCs, favoring drug resistance and tumor relapse.

Trabectedin overcomes doxorubicin-resistance, counteracts tumor-immunosuppressive reprogramming of monocytes and decreases xenograft growth in Hodgkin lymphoma

Classical Hodgkin lymphoma (cHL) tumor cells are surrounded by a protective tumor microenvironment (TME). Trabectedin, an anticancer drug targeting both tumor cells and TME, demonstrated a potent antitumor activity against Hodgkin Reed Sternberg (HRS) cells. It was cytotoxic against cHL cell lines, including the doxorubicin-resistant clones, with subnanomolar IC₅₀ values, and inhibited clonogenic growth and heterospheroid cell viability. It induced necroptosis, caused DNA damage, G2/M cell cycle arrest, and increased reactive oxygen species production. It reduced HRS cell secretion of CCL5, M-CSF, IL-6, IL-13 and TARC, and inhibited migration. Conditioned medium from trabectedin-treated HRS cells was less chemoattractive toward monocytes, mesenchymal stromal cells and lymphocytes, and less effective in educating monocytes to become immunosuppressive macrophages. These monocytes expressed lower levels of indoleamine 2,3-dioxygenase-1, CD206 and PD-L1, secreted lower amounts of IL-10, TARC, and TGF-β, and were less able to inhibit the growth of activated lymphocytes. In vivo, trabectedin inhibited by >75% the growth of cHL murine xenografts with minimal weight loss; tumors of trabectedin-treated mice had fewer TAMs and less angiogenesis. Altogether, this study offers a preclinical rationale for trabectedin use as a new drug candidate in relapsed/refractory cHL patients.

Adipose-Derived Stem Cells Primed with Paclitaxel Inhibit Ovarian Cancer Spheroid Growth and Overcome Paclitaxel Resistance

Adipose-derived stem cells (ADSCs) primed with paclitaxel (PTX) are now hypothesized to represent a potential Trojan horse to vehicle and deliver PTX into tumors. We analyzed the anticancer activity of PTX released by ADSCs primed with PTX (PTX-ADSCs) (~20 ng/mL) in a panel of ovarian cancer (OvCa) cells sensitive or resistant to PTX. We used two (2D) and three dimensional (3D) in vitro models (multicellular tumor spheroids, MCTSs, and heterospheroids) to mimic tumor growth in ascites. The coculture of OvCa cells with PTX-ADSCs inhibited cell viability in 2D models and in 3D heterospheroids (SKOV3-MCTSs plus PTX-ADSCs) and counteracted PTX-resistance in Kuramochi cells. The cytotoxic effects of free PTX and of equivalent amounts of PTX secreted in PTX-ADSC-conditioned medium (CM) were compared. PTX-ADSC-CM decreased OvCa cell proliferation, was more active than free PTX and counteracted PTX-resistance in Kuramochi cells (6.0-fold decrease in the IC50 values). Cells cultivated as 3D aggregated MCTSs were more resistant to PTX than 2D cultivation. PTX-ADSC-CM (equivalent-PTX) was more active than PTX in MCTSs and counteracted PTX-resistance in all cell lines. PTX-ADSC-CM also inhibited OvCa-MCTS dissemination on collagen-coated wells. In conclusion, PTX-ADSCs and PTX-MSCs-CM may represent a new option with which to overcome PTX-resistance in OvCa.

Formation of the Immunosuppressive Microenvironment of Classic Hodgkin Lymphoma and Therapeutic Approaches to Counter It

Classic Hodgkin lymphoma (cHL) is characterized by a few tumor cells surrounded by a protective, immunosuppressive tumor microenvironment composed of normal cells that are an active part of the disease. Hodgkin and Reed-Sternberg (HRS) cells evade the immune system through a variety of different mechanisms. They evade antitumor effector T cells and natural killer cells and promote T cell exhaustion. Using cytokines and extracellular vesicles, they recruit normal cells, induce their proliferation and "educate" (i.e. reprogram) them to become immunosuppressive and protumorigenic. Therefore, alternative treatment strategies are being developed to target not only tumor cells but also the tumor microenvironment. Here we summarize current knowledge on the ability of HRS cells to build their microenvironment and to educate normal cells to become immunosuppressive. We also describe therapeutic strategies to counteract formation of the tumor microenvironment and related processes leading to T cell exhaustion and repolarization of immunosuppressive tumor-associated macrophages.

Potent In Vitro and In Vivo Anticancer Activity of New Bipyridine and Bipyrimidine Gold (III) Dithiocarbamate Derivatives

We synthesized eight new bipyridine and bipyrimidine gold (III) dithiocarbamate-containing complexes (C1-C8) and tested them in a panel of human cancer cell lines. We used osteosarcoma (MG-63), lung (A549), prostate (PC3 and DU145), breast (MCF-7), ovarian (A2780 and A2780cis, cisplatin- and doxorubicin-resistant), and cervical (ME-180 and R-ME-180, cisplatin resistant) cancer cell lines. We found that C2, C3, C6, and C7 were more cytotoxic than cisplatin in all cell lines tested and overcame cisplatin and doxorubicin resistance in A2780cis and R-ME-180 cells. In the PC3 prostate cancer cell line, the gold (III) complex C6 ([Au₂(BPM)(DMDTC)₂]Cl₄) induced apoptosis and double-stranded DNA breaks, modified cell cycle phases, increased Reactive Oxigen Species (ROS) generation, and reduced thioredoxin reductase and proteasome activities. It inhibited PC3 cell migration and was more cytotoxic against PC3 cells than normal human adipose-derived stromal cells. In mice bearing PC3 tumor xenografts, C6 reduced tumor growth by more than 70% without causing weight loss. Altogether, our results demonstrate the anticancer activity of these new gold (III) complexes and support the potential of C6 as a new agent for prostate cancer treatment.

CCR5 antagonism by maraviroc inhibits Hodgkin lymphoma microenvironment interactions and xenograft growth

Classic Hodgkin lymphoma tumor cells express a functional CCR5 receptor, and tumor tissues express high CCL5 levels, suggesting that CCL5-CCR5 signaling is involved in tumor-microenvironment formation and tumor growth. Using the CCR5 antagonist, maraviroc, and a neutralizing anti-CCL5 antibody, we found that CCL5 secreted by classic Hodgkin lymphoma cells recruited mesenchymal stromal cells and monocytes. The “education” of mesenchymal stromal cells by tumor cell-conditioned medium enhanced mesenchymal stromal cells’ proliferation and CCL5 secretion. In turn, educated mesenchymal stromal cell-conditioned medium increased the clonogenic growth of tumor cells and monocyte migration, but these effects were reduced by maraviroc. Monocyte education by tumor cell-conditioned medium induced their growth and reprogrammed them towards immunosuppressive tumor-associated macrophages that expressed IDO and PD-L1 and secreted IL-10, CCL17 and TGF-β. Educated monocyte-conditioned medium slowed the growth of phytohemagglutinin-activated lymphocytes. Maraviroc decreased tumor cell growth and synergized with doxorubicin and brentuximab vedotin. A three-dimensional heterospheroid assay showed that maraviroc counteracted both the formation and viability of heterospheroids generated by co-cultivation of tumor cells with mesenchymal stromal cells and monocytes. In mice bearing tumor cell xenografts, maraviroc reduced tumor growth by more than 50% and inhibited monocyte accumulation, without weight loss. Finally, in classic Hodgkin lymphoma human tumor tissues, CCL5 and CD68 expression correlated positively, and patients with high CCL5 levels had poor prognosis. In conclusion, since the present challenges are to find molecules counteracting the formation of the immunosuppressive tumor microenvironment or new, less toxic drug combinations, the repurposed drug maraviroc may represent a new opportunity for classic Hodgkin lym phoma treatment.

Improved GMP compliant approach to manipulate lipoaspirates, to cryopreserve stromal vascular fraction, and to expand adipose stem cells in xeno-free media

Background

The stromal vascular fraction (SVF) derived from adipose tissue contains adipose-derived stromal/stem cells (ASC) and can be used for regenerative applications. Thus, a validated protocol for SVF isolation, freezing, and thawing is required to manage product administration. To comply with Good Manufacturing Practice (GMP), fetal bovine serum (FBS), used to expand ASC in vitro, could be replaced by growth factors from platelet concentrates.

Methods

Throughout each protocol, GMP-compliant reagents and devices were used. SVF cells were isolated from lipoaspirates by a standardized enzymatic protocol. Cells were cryopreserved in solutions containing different albumin or serum and dimethylsulfoxide (DMSO) concentrations. Before and after cryopreservation, we analyzed: cell viability (by Trypan blue); immunophenotype (by flow cytometry); colony-forming unit-fibroblast (CFU-F) formation; and differentiation potential. ASC, seeded at different densities, were expanded in presence of 10% FBS or 5% supernatant rich in growth factors (SRGF) from platelets. The differentiation potential and cell transformation grade were tested in expanded ASC.

Results

We demonstrated that SVF can be obtained with a consistent yield (about 185 × 10³ cells/ml lipoaspirate) and viability (about 82%). Lipoaspirate manipulation after overnight storage at +4 °C reduced cell viability (−11.6%). The relative abundance of ASC (CD34⁺CD45⁻CD31^–) and endothelial precursors (CD34⁺CD45⁻CD31⁺) in the SVF product was about 59% and 42%, respectively. A period of 2 months cryostorage in autologous serum with added DMSO minimally affected post-thaw SVF cell viability as well as clonogenic and differentiation potentials. Viability was negatively affected when SVF was frozen at a cell concentration below 1.3 × 10⁶ cells/ml. Cell viability was not significantly affected after a freezing period of 1 year.

Independent of seeding density, ASC cultured in 5% SRGF exhibited higher growth rates when compared with 10% FBS. ASC expanded in both media showed unaltered identity (by flow cytometry) and were exempt from genetic lesions. Both 5% SRGF- and 10% FBS-expanded ASC efficiently differentiated to adipocytes, osteocytes, and chondrocytes.

Conclusions

This paper reports a GMP-compliant approach for freezing SVF cells isolated from adipose tissue by a standardized protocol. Moreover, an ASC expansion method in controlled culture conditions and without involvement of animal-derived additives was reported.

New bipyridine gold(III) dithiocarbamate-containing complexes exerted a potent anticancer activity against cisplatin-resistant cancer cells independent of p53 status

We synthesized, characterized and tested in a panel of cancer cell lines, nine new bipyridine gold(III) dithiocarbamate-containing complexes. In vitro studies demonstrated that compounds 1, 2, 4, 5, 7 and 8 were the most cytotoxic in prostate, breast, ovarian cancer cell lines and in Hodgkin lymphoma cells with IC₅₀ values lower than the reference drug cisplatin. The most active compound 1 was more active than cisplatin in ovarian (A2780cis and 2780CP-16) and breast cancer cisplatin-resistant cells. Compound 1 determined an alteration of the cellular redox homeostasis leading to increased ROS levels, a decrease in the mitochondrial membrane potential, cytochrome-c release from the mitochondria and activation of caspases 9 and 3. The ROS scavenger NAC suppressed ROS generation and rescued cells from damage. Compound 1 resulted more active in tumor cells than in normal human Mesenchymal stromal cells. Gold compounds were active independent of p53 status: exerted cytotoxic effects on a panel of non-small cell lung cancer cell lines with different p53 status and in the ovarian A2780 model where the p53 was knocked out. In conclusion, these promising results strongly indicate the need for further preclinical evaluation to test the clinical potential of these new gold(III) complexes.

Radiotherapy prolongs the survival of advanced non-small-cell lung cancer patients undergone to an immune-modulating treatment with dose-fractioned cisplatin and metronomic etoposide and bevacizumab (mPEBev)

Radiotherapy (RT), together with a direct cytolytic effect on tumor tissue, also elicits systemic immunological events, which sometimes result in the regression of distant metastases (abscopal effect). We have shown the safety and anti-tumor activity of a novel metronomic chemotherapy (mCH) regimen with dose-fractioned cisplatin, oral etoposide and bevacizumab, a mAb against the vasculo-endothelial-growth-factor (mPEBev regimen), in metastatic non-small-cell-lung cancer (mNSCLC). This regimen, designed on the results of translational studies, showed immune-modulating effects that could trigger and empower the immunological effects associated with tumor irradiation. In order to assess this, we carried out a retrospective analysis in a subset of 69 consecutive patients who received the mPEBev regimen within the BEVA2007 trial. Forty-five of these patients, also received palliative RT of one or more metastatic sites. Statistical analysis (a Log-rank test) revealed a much longer median survival in the group of patients who received RT [mCH vs mCH + RT: 12.1 +/-2.5 (95%CI 3.35-8.6) vs 22.12 +/-4.3 (95%CI 11.9-26.087) months; P=0.015] with no difference in progression-free survival. In particular, their survival correlated with the mPEBev regimen ability to induce the percentage of activated dendritic cells (DCs) (CD3-CD11b+CD15-CD83+CD80+) [Fold to baseline value (FBV) ≤1 vs >1: 4+/-5.389 (95%CI,0- 14.56) vs 56+/-23.05 (95%CI,10.8-101.2) months; P:0.049)] and central-memory- T-cells (CD3+CD8+CD45RA-CCR7+) [FBV ≤ 1 vs >1: 8+/-5.96 (95%CI,0-19.68) vs 31+/-12.3 (95%CI,6.94-55.1) months; P:0.045]. These results suggest that tumor irradiation may prolong the survival of NSCLC patients undergone mPEBev regimen presumably by eliciting an immune-mediated effect and provide the rationale for further perspective clinical studies.

Clinical-grade quality platelet-rich plasma releasate (PRP-R/SRGF) from CaCl2 -activated platelet concentrates promoted expansion of mesenchymal stromal cells

BACKGROUND AND OBJECTIVES

The aim of our study was to test a platelet-rich plasma releasate (PRP-R/SRGF) from CaCl2 -activated platelets as a source of growth factors for the expansion of mesenchymal stromal cells (MSCs). PRP-R/SRGF, obtained with a low-cost procedure, is characterized by a reduced variability of growth factor release.

MATERIALS AND METHODS

PRP-R/SRGF is a clinical-grade quality solution obtained from CaCl2 -activated platelets. Its activity was evaluated by measuring the proliferation, the phenotype, the differentiation potential and the immunosuppressive properties of MSCs derived from bone marrow (BM) and adipose tissue (AT).

RESULTS

PRP-R/SRGF was more active than FBS to expand BM- and AT-derived MSCs. PRP-R/SRGF treatment did not affect the expression of typical MSCs surface markers, neither MSCs differentiation potential nor their capability to inhibit activated T-cell proliferation.

CONCLUSIONS

The clinical-grade PRP-R/SRGF may be used in the clinical setting for the expansion of MSCs.

Preclinical activity of the liposomal cisplatin lipoplatin in ovarian cancer

PURPOSE

Cisplatin and its platinum derivatives are first-line chemotherapeutic agents in the treatment of ovarian cancer; however, treatment is associated with tumor resistance and significant toxicity. Here we investigated the antitumoral activity of lipoplatin, one of the most promising liposomal platinum drug formulations under clinical investigation.

EXPERIMENTAL DESIGN

In vitro effects of lipoplatin were tested on a panel of ovarian cancer cell lines, sensitive and resistant to cisplatin, using both two-dimensional (2D) and 3D cell models. We evaluated in vivo the lipoplatin anticancer activity using tumor xenografts.

RESULTS

Lipoplatin exhibited a potent antitumoral activity in all ovarian cancer cell lines tested, induced apoptosis, and activated caspase-9, -8, and -3, downregulating Bcl-2 and upregulating Bax. Lipoplatin inhibited thioredoxin reductase enzymatic activity and increased reactive oxygen species accumulation and reduced EGF receptor (EGFR) expression and inhibited cell invasion. Lipoplatin demonstrated a synergistic effect when used in combination with doxorubicin, widely used in relapsed ovarian cancer treatment, and with the albumin-bound paclitaxel, Abraxane. Lipoplatin decreased both ALDH and CD133 expression, markers of ovarian cancer stem cells. Multicellular aggregates/spheroids are present in ascites of patients and most contribute to the spreading to secondary sites. Lipoplatin decreased spheroids growth, vitality, and cell migration out of preformed spheroids. Finally, lipoplatin inhibited more than 90% tumor xenograft growth with minimal systemic toxicity, and after the treatment suspension, no tumor progression was observed.

CONCLUSION

These preclinical data suggest that lipoplatin has potential for clinical assessment in aggressive cisplatin-resistant patients with ovarian cancer.

Gefitinib inhibits the cross-talk between mesenchymal stem cells and prostate cancer cells leading to tumor cell proliferation and inhibition of docetaxel activity

Increasing evidence suggests that bone marrow derived mesenchymal stem cells (BM-MSCs) are recruited into the stroma of developing tumors where they contribute to progression by enhancing tumor growth and metastasis, or by inducing anticancer-drug resistance. Prostate cancer cells secrete ligands of epidermal growth factor receptor (EGFR) and EGFR signaling could play an important role in the cross-talk between mesenchymal stem cells and prostate cancer cells. In this study, we showed that treatment of human primary MSCs with conditioned medium (CM) derived from the bone metastatic PC3 carcinoma cells (PC3-CM) resulted in: a significant activation of EGFR; increased proliferation; increased osteoblastic but decreased adipocitic differentiation; inhibition of senescence induced by serum starvation; increased CCL5 secretion. These activities were significantly inhibited in the presence of the EGFR tyrosine kinase inhibitor gefitinib. PC3-CM directly inhibited osteoclastogenesis as well as the ability of osteoblasts to induce osteoclast differentiation. The increased MSCs migration by PC3-CM and PC3 cells was partially mediated by CCL5. MSC-CM increased the formation of colonies by PC3 cells and inhibited the anti-proliferative activity of Docetaxel. Activation of EGFR expressed on MSCs by PC3-CM enhanced their capability to increase PC3 cells proliferation and to inhibit Docetaxel activity. These findings, by showing that the tumor-promoting interactions between PC3 cells and MSCs are mediated, at least in part, by EGFR, suggest a novel application of the EGFR-tyrosine kinase inhibitors in the treatment of prostate cancer.

Toward the selective delivery of chemotherapeutics into tumor cells by targeting peptide transporters: tailored gold-based anticancer peptidomimetics

Complexes [Au(III)X(2)(dtc-Sar-AA-O(t-Bu))] (AA = Gly, X = Br (1)/Cl (2); AA = Aib, X = Br (3)/Cl (4); AA = l-Phe, X = Br (5)/Cl (6)) were designed on purpose in order to obtain gold(III)-based anticancer peptidomimetics that might specifically target two peptide transporters (namely, PEPT1 and PEPT2) upregulated in several tumor cells. All the compounds were characterized by means of FT-IR and mono- and multidimensional NMR spectroscopy, and the crystal structure of [Au(III)Br(2)(dtc-Sar-Aib-O(t-Bu))] (3) was solved and refined. According to in vitro cytotoxicity studies, the Aib-containing complexes 3 and 4 turned out to be the most effective toward all the human tumor cell lines evaluated (PC3, DU145, 2008, C13, and L540), reporting IC(50) values much lower than that of cisplatin. Remarkably, they showed no cross-resistance with cisplatin itself and were proved to inhibit tumor cell proliferation by inducing either apoptosis or late apoptosis/necrosis depending on the cell lines. Biological results are here reported and discussed in terms of the structure-activity relationship.

The role of CD40/CD40L and interferon regulatory factor 4 in Hodgkin lymphoma microenvironment

Inflammation and cancer are two independent biological events that can play an interdependent role. The model of such interaction is represented by Hodgkin lymphoma (HL), where the microenvironment is dominated by an extensive mixed, potentially cellular inflammatory infiltrate that plays a decisive role in the pathobiology of HL. In this review we summarize updated information on the complex interactions between Hodgkin Reed-Sternberg (HRS) cells and their tissue microenvironment, highlighting the functional role of CD40/CD40L and interferon regulatory factor 4 (IRF4).

Role of the EGFR ligand/receptor system in the secretion of angiogenic factors in mesenchymal stem cells

Increasing evidence suggests that bone marrow-derived mesenchymal stem cells (MSCs) are recruited into the stroma of developing tumors where they contribute to cancer progression. MSCs produce different growth factors that sustain tumor-associated neo-angiogenesis. Since the majority of carcinomas secrete ligands of the epidermal growth factor receptor (EGFR), we assessed the role of EGFR signaling in regulating the release of angiogenic factors in MSCs. Treatment of human primary MSCs and of the human osteoblastic cell line hFOB with transforming growth factor α (TGF-α), one of the main ligands of the EGFR, significantly induced activation of this receptor and of different intracellular signaling proteins, including the PI3K/AKT and the MEK/MAPK pathways. TGF-α induced a significant increase in the levels of secretion of vascular endothelial growth factor in both MSCs and hFOB. Conditioned medium from TGF-α treated MSCs showed an higher in vivo angiogenic effect as compared with medium from untreated cells. Treatment of MSCs with TGF-α also produced a significant increase in the secretion of other angiogenic growth factors such as angiopoietin-2, granulocyte-colony stimulating factor, hepatocyte growth factor, interleukin (IL)-6, IL-8, and platelet-derived growth factor-BB. Using selective MEK and PI3K inhibitors, we found that both MEK/MAPK and the PI3K/AKT signaling pathways mediate the ability of TGF-α to induce secretion of angiogenic factors in MSCs. Finally, stimulation with TGF-α increased the ability of MSCs to induce migration of MCF-7 breast cancer cells. These data suggest that EGFR signaling regulates the ability of MSCs to sustain cancer progression through the release of growth factors that promote neo-angiogenesis and tumor cell migration.

Antitumor activity of gold(III)-dithiocarbamato derivatives on prostate cancer cells and xenografts

Among the nonplatinum antitumor drugs, gold(III)-dithiocarbamato derivatives have recently attracted considerable attention due to their strong in vitro and in vivo antiproliferative activity and reduced renal toxicity. Some of them, namely [AuCl(2) (DMDT)] (compound 1) and [AuBr(2) (ESDT)] (compound 2), have shown to be highly active against the androgen-resistant prostate cancer cell lines PC3 and DU145, both inhibiting cell proliferation in a dose-dependent way, and are more active than the reference drug cisplatin (cis-[PtCl(2) (NH(3) )(2) ]). In particular, [AuCl(2) (DMDT)] was proved cytotoxic against cisplatin-resistant R-PC3 cells, with activity levels comparable to those induced on the parent cisplatin-sensitive PC3 cells, ruling out the occurrence of cross-resistance phenomena. Moreover, it causes early cell damage, slightly affecting the cell cycle, thus suggesting a different mechanism of action from clinically established platinum-based drugs. In fact, the investigated gold(III) complex alters mitochondrial functions, promoting mitochondrial membrane permeabilization and Cyt-c release, stimulating ROS generation, and strongly inhibiting the activity of the selenoenzyme TrxR, which is overexpressed in prostate cancer and associated with the onset of drug resistance. In addition, it induces apoptosis, caspase activation, Bcl-2 downregulation and Bax upregulation, reduces the expression of the phosphorylated form of the EGFR, and it inhibits PC3 cell migration. Finally, the treatment of PC3 prostate tumor-bearing nude mice with [AuCl(2) (DMDT)] significantly inhibited tumor growth in vivo, causing minimal systemic toxicity. Altogether, our results confirm that these gold(III)-dithiocarbamato derivatives have potential for the treatment of prostate cancer.

IRF4 silencing inhibits Hodgkin lymphoma cell proliferation, survival and CCL5 secretion

Interferon regulatory factor 4 (IRF4) expression is detected in many lymphoid and myeloid malignancies, and may be a promising therapeutic target. IRF4 is strongly expressed in classical Hodgkin lymphoma (cHL) and its expression is up-regulated by CD40L and down-regulated by both anti-proliferative and pro-apoptotic stimuli. This study analysed the effects of IRF4 silencing in a panel of HL-derived cell lines. We demonstrated that IRF4 down-modulation determined a remarkable decrease of both cell number and clonogenic growth in L-1236, L-428, KM-H2 and HDLM-2 cells, but not in IRF4-negative L-540 cells. IRF4 silencing induced apoptosis, as evaluated by caspase-3 activation and Annexin-V staining and up-regulation of the pro-apoptotic molecule Bax. CD40 engagement by both soluble and membrane bound-CD40L almost totally reduced IRF4 down-modulation and growth inhibition by IRF4 silencing in both L-1236 and L-428 cells. Finally, IRF4 silencing decreased CCL5 secretion in all HL cell lines tested and CCL17 in KM-H2 cells. Taken together, our results demonstrated that IRF4 down-modulation by IRF4 silencing was reversed by CD40 engagement, inhibited HL cells proliferation, induced apoptosis and decreased CCL5 secretion, thus suggesting that IRF4 may be involved in HL pathobiology.

Latest insights into the anticancer activity of gold(III)-dithiocarbamato complexes

In this review paper we aim at giving a detailed overview on our research work devoted to the design of gold-based anticancer agents. In particular, during the last decade, we have been developing some gold(III)-dithiocarbamato derivates showing outstanding in vitro and in vivo antitumor properties and reduced, or even no, systemic and renal toxicity, compared to the reference clinically-established anticancer drug cisplatin. Starting from the rationale behind our investigations, we here summarize the results achieved so far, focusing on the latest in-depth mechanistic studies that have recently provided insights into their mechanism of action, thus opening up new prospects for further pharmacological testing and, hopefully, to enter clinical trials.

IRF4 is modulated by CD40L and by apoptotic and anti-proliferative signals in Hodgkin lymphoma

The effects of proliferative, apoptotic and anti-proliferative stimuli on interferon regulatory factor 4 (IRF4) expression by Reed-Sternberg (RS) cells were analysed using a panel of Hodgkin lymphoma (HL)-derived cell lines. IRF4 expressed by HL cells was consistently upregulated after CD40 engagement; IRF4 was downregulated by agonistic anti-CD95 antibodies in the FAS-sensitive HDLM-2 cells and after treatment with Adriamycin and Dacarbazine, two chemotherapic agents commonly used for HL treatment. These results demonstrated, for the first time, that IRF4 was up-modulated by CD40 engagement, and down-modulated by apoptotic and anti-proliferative signals, suggesting an involvement of IRF4 also in HL pathobiology.

Functional coexpression of Interleukin (IL)-7 and its receptor (IL-7R) on Hodgkin and Reed-Sternberg cells: Involvement of IL-7 in tumor cell growth and microenvironmental interactions of Hodgkin's lymphoma

The clinical and pathological features of classical Hodgkin lymphoma (cHL) mirror an abnormal tissue and systemic immune response due to the production of a variety of cytokines and chemokines by the malignant Hodgkin-Reed-Sternberg (H-RS) cells and/or surrounding reactive cells. Here, we demonstrate that HL-derived cell lines (L-428, KM-H2, HDLM-2, L-1236 and L-540) and primary H-RS cells from lymph node tissues of HL patients express the IL-7(R) receptor. IL-7 appears to be involved in autocrine circuitries of HL because L-1236, HDLM-2 and KM-H2 cells display the constitutive production of IL-7 and neutralizing anti-IL-7 antibodies induces a statistically significant inhibition of their basal proliferation. In addition, IL-7, either exogenous or fibroblasts-derived, promotes the clonogenic growth and reduces apoptosis of cultured H-RS cells, being also able to partially protect these cells from the cytotoxic effects of doxorubicin. We also provide evidence that IL-7 stimulates IL-6 secretion from IL-7R-expressing fibroblasts from HL-involved lymph nodes (HLFs), and that a striking increase in IL-6 secretion can be observed in cocultures of HLFs with L1236 cells. Finally, we show that L-1236 cells-derived IL-7 represents a costimulator for proliferation of purified CD4+CD25+CD127(dim/-) regulatory T cells (Tregs). Taken together, our data indicates that the IL-7/IL-7R axis constitutes an additional signaling pathway between H-RS cells and their reactive cellular background, thereby affecting proliferation and survival of tumor cells, acting as a cofactor for Tregs expansion and enhancing the microenviromental production of IL-6, a cytokine associated with the presence of "B" symptoms and a poor outcome in HL patients.

Biologic and clinical significance of cytokine production in B-cell malignancies

Cytokines are a group of polypeptide hormones endowed with pleiotropic biological properties. Normal B lymphocytes produce a number of these factors that subserve important regulatory functions in the combined processes of proliferation and differentiation. Also neoplastic B cells can release cytokines and, simultaneously, respond to the same factors in an autocrine circuit that supports their malignant growth. In addition, tumor cells can make use of the factors released by normal cells, either spontaneously or under the influence of inductive signals from the neoplastic cells. Inappropriate or excessive release of cytokines may have an important role in the pathophysiology of some clinical features. Thus, neutralization of cytokine biologic activity in vivo could be a therapeutic strategy for treatment of human B-cell neoplasias.

The role of the EGFR signaling in tumor microenvironment

The epidermal growth factor receptor (EGFR) family comprehends four different tyrosine kinases (EGFR, ErbB-2, ErbB-3, and ErbB-4) that are activated following binding to epidermal growth factor (EGF)-like growth factors. It has been long established that the EGFR system is involved in tumorigenesis. These proteins are frequently expressed in human carcinomas and support proliferation and survival of cancer cells. However, activation of the EGFR in non-malignant cell populations of the neoplastic microenvironment might also play an important role in cancer progression. EGFR signaling regulates in tumor cells the synthesis and secretion of several different angiogenic growth factors, including vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), and basic fibroblast growth factor (bFGF). Overexpression of ErbB-2 also leads to increased expression of angiogenic growth factors, whereas treatment with anti-EGFR or anti-ErbB-2 agents produces a significant reduction of the synthesis of these proteins by cancer cells. EGFR expression and function in tumor-associated endothelial cells has also been described. Therefore, EGFR signaling might regulate angiogenesis both directly and indirectly. In addition, activation of EGFR is involved in the pathogenesis of bone metastases. Within the bone marrow microenvironment, cancer cells stimulate the synthesis of osteoclastogenic factors by residing stromal cells, a phenomenon that leads to bone destruction. It has been shown that EGFR signaling regulates the ability of bone marrow stromal cells to produce osteoclastogenic factors and to sustain osteoclast activation. Taken together, these findings suggest that the EGFR system is an important mediator, within the tumor microenvironment, of autocrine and paracrine circuits that result in enhanced tumor growth.

Expression of CCR5 receptors on Reed-Sternberg cells and Hodgkin lymphoma cell lines: involvement of CCL5/Rantes in tumor cell growth and microenvironmental interactions

The expression of CCL5/Rantes by Hodgkin (H) and Reed-Sternberg (RS) cells has been recently documented. In the present study we demonstrated that the CCL5 receptor (CCR5) is constitutively expressed by Hodgkin Lymphoma (HL)-derived cell lines (i.e. L-428, KM-H2, L-1236 and L-540) as shown by immunohistochemistry, flow cytometry and western blotting and also detected by immunohistochemistry on primary H-RS cells from lymph node tissues. sCD40L never significantly affected CCR5 expression, whereas a short exposure to doxorubicin down regulated its expression. CCR5 receptors on HL cell lines were functionally active, since neutralizing anti-CCL5 monoclonal antibodies inhibited basal proliferation of HL-derived cell lines and recombinant CCR5 ligands (CCL3/Mip-1 alpha, CCL4/Mip1 beta and CCL5/Rantes) increased their clonogenic growth. CCL5 secretion by L-1236, L-428 and KM-H2 cells was stimulated by CD40 engagement and also by coculturing L-1236 cells on primary stromal fibroblasts from HL-involved lymph nodes (HLF). Coculture experiments indicated that a direct contact of H-RS cells induces HLF cells to produce CCL5. Supernatants from L-1236, L-428 and KM-H2 cells stimulated migration of purified CD4+ T-cells and eosinophils in vitro. The migratory response to HL-cell lines supernatants was only partially neutralized (CD4+ cells: 70%; esinophils: 36%) by anti-CCL5 antibodies, reinforcing the notion that multiple chemokines are involved in the recruitment of nonmalignant reactive cells in HL tissues. Taken together, our results indicate a possible involvement of the CCR5/CCR5-ligands signaling in the regulation of H-RS cells growth and in the formation/maintenance of the typical tissue microenvironment of HL.

Antiproliferative and apoptotic effects of two new gold(III) methylsarcosinedithiocarbamate derivatives on human acute myeloid leukemia cells in vitro

[Au(MSDT)Cl2] (dichloro[methyl N-(dithiocarboxy-kS,kS')-N-methylglicinato]gold(III)) and [Au(MSDT)Br2] (dibromo[methyl N-(dithiocarboxy-kS,kS')-N-methylglicinato]gold(III)) gold(III) dithiocarbamate derivatives are two newly synthesized gold(III) derivatives of methylsarcosinedithiocarbamate, containing a sulfur chelating ligand that is able to bind the metal center strongly, so preventing interactions with sulfur-containing enzymes; in fact these reactions are believed to be responsible for the nephrotoxicity induced by the platinum(II)-based drugs. Their activity has been compared with the well-known platinum-based anticancer agent cisplatin on a panel of acute myelogenous leukemia cell lines representing different French-American-British subtypes and in the Philadelphia-positive cell line K562. Both compounds suppressed, in a dose-dependent manner, colony formation in methylcellulose with ID50 values of about 10-fold lower than that of the reference drug. After a short exposure (18 h), our compounds, but not cisplatin, were able to: downregulate the antiapoptotic molecule Bcl-2, upregulate the proapoptotic molecule Bax and induce apoptosis, as determined by a strong induction of APO2.7 and phosphatidylserine exposure. Finally, after a 72-h exposure, both gold(III) dithiocarbamate derivatives determined modest cell cycle modifications, but induced DNA fragmentation in all myeloid cell lines tested. Altogether, our results indicate that these new gold(III) dithiocarbamate derivatives might represent novel potentially active drugs for the management of myeloid leukemia, able to combine cytostatic and apoptotic activity with reduced nephrotoxicity.

The role of interleukin-3 in classical Hodgkin's disease

Classical Hodgkin's disease (HD) is a peculiar form of lymphoma characterized by a low frequency of tumor cells, the so-called Hodgkin (H) and Reed/Sternberg (RS) cells, embedded in a background of non-neoplastic (reactive) cells believed to be recruited and activated by H-RS cell-derived cytokines/chemokines. How these tumor cells can survive in such a seemingly hostile environment has confused researchers. We have previously identified interleukin (IL)-3 receptor (R) expression as a common feature of classical HD and unveiled the potential role of IL-3 as a growth and anti-apoptotic factor for H-RS cells. More then 90% of malignant cells of classical HD usually express the alpha chain of the IL-3R (IL-3R(alpha)), as evidenced by immunostaining of frozen sections and cell suspensions from neoplastic lymph nodes. Consistently, HD-derived cell lines (L428, KMH2, HDLM2 and L1236) express the alpha and beta chains that form IL-3R, both at the mRNA and protein level, with a molecular size of IL-3R(alpha) identical (70 kDa) to that expressed by human myeloid cells. Exogenous IL-3 promotes the growth of cultured H-RS cells, such an effect being potentiated by IL-9 and stem cell factor (SCF) co-stimulation, and is able to partially rescue tumor cells from apoptosis induced by serum deprivation. Finally, cultured H-RS cells are able to increase the production of IL-3 by pre-activated T cells, suggesting an involvement of IL-3/IL-3R interactions in the cellular growth of HD through paracrine mechanisms. This review will outline the biological activity of IL-3 and summarize the evidence indicating IL-3 as a growth and anti-apoptotic factor for H-RS cells in classical HD.

Gefitinib inhibits the ability of human bone marrow stromal cells to induce osteoclast differentiation: implications for the pathogenesis and treatment of bone metastasis

Significant relief of bone pain in patients with bone metastases was observed in a clinical trial of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib in breast cancer. Osteoclast activation and differentiation are regulated by bone marrow stromal cells (BMSC), a heterogeneous cell compartment that comprehends undifferentiated mesenchymal stem cells (MSC) and their specialized progeny. In this regard, we found that human primary BMSCs express immunoreactive EGFR. Expression of EGFR mRNA and protein was also demonstrated in two human, continuous MSC-like cell lines, HDS-1 and HDS-2 cells. Treatment of HDS cells with EGF produced a significant increase in the levels of activated EGFR which was not observed in the presence of gefitinib. A significant reduction in the basal levels of activation of the EGFR and of Akt was observed in HDS cells following treatment with gefitinib. Treatment of HDS cells with gefitinib produced a significant reduction in the levels of secreted macrophage colony-stimulating factor (M-CSF) and cell-associated receptor activator of NF-kappaB ligand (RANKL) in both cell lines, as assessed by using specific ELISA and Western blotting techniques. Finally, the ability to sustain the differentiation of pre-osteoclasts of conditioned medium from gefitinib-treated HDS cells was reduced by approximately 45% as compared with untreated HDS cells. These data have demonstrated for the first time that the EGFR regulates the ability of BMSCs to induce osteoclast differentiation and strongly support clinical trials of gefitinib in breast cancer patients with bone disease.

Pentostatin (2'-deoxycoformycin) for the treatment of hepatosplenic gammadelta T-cell lymphomas

We report the results of treatment with single agent 2'-deoxycoformycin (Pentostatin) in two patients with Hepatosplenic gammadelta T-cell lymphoma (HSgammadeltaTCL), a rare lymphoma subtype with a highly unfavorable prognosis. Present and previous data reviewed here demonstrates the striking cytotoxic activity of Pentostatin against gammadelta+ tumor T cells. Further studies are warranted to define the optimal strategy to fully exploit therapeutic potential of this drug in patients with HSgammadeltaTCL.

Synthesis, Characterization, and Comparative in Vitro Cytotoxicity Studies of Platinum(II), Palladium(II), and Gold(III) Methylsarcosinedithiocarbamate Complexes

This work reports on the synthesis, characterization, and in vitro cytotoxic activity of some new platinum(II), palladium(II), and gold(III) derivatives of methylsarcosinedithiocarbamate and its S-methyl ester, to study their behavior as potential antitumor agents. The biological activity of these compounds, as determined by growth inhibition and apoptosis induction, has been investigated in both human leukemic promyelocites HL60 and human squamous cervical adenocarcinoma HeLa cell lines, and their activity has been compared to the well-known platinum-based anticancer agent cisplatin. On the basis of these experimental results, [Pd(MSDT)X]n (MSDT = methylsarcosinedithiocarbamate; X = Cl, Br) complexes show a strong dose-dependent growth inhibition of both HL60 and HeLa cells, with IC(50) values slightly higher than those recorded for cisplatin; moreover, [Au(MSDT)X(2)] activity appears significantly higher or, at least, comparable to that of the reference drug. Exposure of both cell lines to [Pd(MSDT)X]n and [Au(MSDT)X(2)] complexes induces apoptosis, as determined by an Apo2.7 assay.

Interactions between tissue fibroblasts in lymph nodes and Hodgkin/Reed-Sternberg cells

Classic Hodgkin's Disease (cHD) is a lymphoid neoplasia characterized by a few malignant Hodgkin and Reed-Sternberg (H-RS) cells embedded in an abundant background of non-tumor cells. In this context, fibrosis is a common morphologic feature of HD lesions, being found more frequently in cHD subtypes. The clinical and histopathologic features of cHD are thought to be largely due to the effects of a wide variety of cytokines and chemokines primarily produced by H-RS cells, as well as by the surrounding reactive component. In the present review, first we propose three mechanisms putatively explaining fibroblast activation and fibrosis in HD: (1) unbalanced production of the pro-fibrogenic Th2 over Th1 cytokines; (2) production of TGF-beta, b-FGF and IL-13 by H-RS cells; (3) activation of fibroblasts by CD40L-expressing cells of the HD microenvironment. Second, we suggest some molecular pathways involving cytokines produced by HD-derived fibroblasts (SCF, IL-7, IL-6) supposedly responsible for H-RS proliferation and rescue from apoptosis. Finally, we describe the role of specific molecules produced by H-RS cells in the regulation of HD-derived fibroblast production of chemokines, in turn involved in T-lymphocytes and recruitment of eosinophils.

CD26 expression correlates with a reduced sensitivity to 2'-deoxycoformycin-induced growth inhibition and apoptosis in T-cell leukemia/lymphomas

PURPOSE AND EXPERIMENTAL DESIGN

dCF (2'-deoxycoformycin) is a potent inhibitor of ADA (adenosine deaminase), an enzyme regulating intra- and extracellular concentrations of purine metabolites. ADA exists as cytosolic and extracellular forms, the latter colocalized on the cell surface with CD26. Once the surface expression of CD26 and ADA in a panel of cell lines and primary samples of T-cell leukemia/lymphoma was defined, we correlated this expression with the antiproliferative and apoptotic effect of dCF.

RESULTS

Surface expression of CD26 inversely correlated with the capability of dCF to inhibit cell growth and induce apoptosis both in T-cell lines and primary samples of T-cell malignancies. This conclusion was sustained by a decreased sensitivity to dCF-mediated proapoptotic and/or antiproliferative in vitro effects of: (a) leukemia/lymphoma T-cell lines expressing surface CD26/ADA complex; (b) primary CD26(+) T cell malignancies; and (c) normal T cells (CD26(+)) as compared with tumor T cells (CD26(-)) in unpurified samples from three cases of T-cell receptor gammadelta(+) T-cell malignancies characterized by a mixture of normal and neoplastic cells. This latter point was confirmed in vivo, in a patient affected by CD26(-) T-cell receptor gammadelta(+) hepatosplenic gammadelta(+) T-cell lymphomas treated on a compassionate basis with dCF. The inverse correlation between CD26 expression and sensitivity to dCF was also demonstrated in a lymphoblastic lymphoma case in which CD26 was expressed on circulating blasts at relapse but not at diagnosis, as well as in two H9 T-cell clones expressing or not expressing CD26 mRNA and protein.

CONCLUSIONS

This study corroborates the notion of CD26 as a marker of poor prognosis for T-cell malignancies and delineates a role for CD26 as a predictor of poor response to dCF.

CD40L induces proliferation, self-renewal, rescue from apoptosis, and production of cytokines by CD40-expressing AML blasts

OBJECTIVE

Conflicting experimental and clinical results have been reported regarding the role of CD40 in acute myeloid leukemia (AML). In the present study, we analyzed the capability of CD40L/CD154 to modulate several functional aspects of CD40-expressing AML blasts.

METHODS

After defining the constitutive expression levels of CD40 in a wide panel (n = 67) of AMLs and evaluating the capability of cytokines to modulate its expression, we investigated the effects of CD40 engagement by soluble (s) CD40L on proliferation, self-renewal capacity, apoptosis, homotypic adhesion, and cytokine production of leukemia cells.

RESULTS

CD40 was detected in blast cells from about 37% of AMLs, the highest frequency being documented in monocytic subtypes, and its expression was upregulated or de novo induced by treatment with interleukin (IL)-1alpha, IL-3, IL-4, granulocyte-macrophage colony-stimulating factor (GM-CSF), interferon-gamma, and tumor necrosis factor-alpha. Exposure of CD40(+) AML blasts to sCD40L resulted in a dose-dependent proliferative response, enhancement of clonogenic growth and self-renewal capacity, and a striking increase in colony size. CD40 engagement was able to rescue AML blasts from apoptosis induced by serum deprivation, as demonstrated by reduced expression of APO2.7 and annexin-V binding, as well as upregulation of the anti-apoptotic protein bcl-x(L). CD40 triggering upregulated cell surface expression of the adhesion molecules CD54, CD58, and CD15 and resulted in homotypic aggregation of leukemia cells at least in part CD54-dependent. An increased production of IL-6 and GM-CSF by CD40(+) AML blasts was also documented upon sCD40L exposure.

CONCLUSIONS

This study indicates a possible involvement of CD40 in the interactions of AML blasts with other growth-sustaining microenvironmental accessory cells and immune effectors, in turn expressing CD40L. Caution in the use of CD40 triggering in immunotherapy of AMLs is also suggested.

Hodgkin and Reed-Sternberg cells express functional c-kit receptors and interact with primary fibroblasts from Hodgkin's disease-involved lymph nodes through soluble and membrane-bound stem cell factor

Classic Hodgkin's disease (cHD) is a lymphoid neoplasia characterized by few malignant Hodgkin and Reed-Sternberg (H-RS) cells, embedded in an abundant background of non-tumour cells. We have previously demonstrated the expression in primary H-RS cells of the receptor tyrosine kinase (RTK) c-kit; here we describe its functional role in the cross-talk between H-RS cells themselves with neighbouring cell populations. In particular, we analysed the expression of c-kit and its ligand stem cell factor (SCF) in a panel of HD-derived cell lines and fibroblasts from HD-involved lymph nodes (HDF). While c-kit was expressed by HD-derived cell lines, usually in the absence of SCF, this latter molecule, in its soluble and/or membrane-bound (mb) form, was in turn expressed at a high level by primary HDF. In vitro adhesion between HD-derived cell lines and HDF was mainly mediated by c-kit/SCF interactions, and this phenomenon was significantly inhibited by an excess of soluble SCF or by neutralizing anti-c-kit monoclonal antibodies. Furthermore, both soluble and mb-SCF increased growth and colony survival of HD-derived cell lines; these effects were significantly enhanced upon co-stimulation of H-RS cells with interleukin 9. Finally, soluble SCF was able to partially rescue H-RS cells from apoptosis induced by serum starvation. Taken together, our data indicated the expression of functional c-kit receptor by H-RS cells and suggests a role of SCF in the pathobiology of cHD.

A novel bcl-1/JH breakpoint from a patient affected by mantle cell lymphoma extends the major translocation cluster

Mantle cell lymphoma (MCL) is a B-lymphocytic malignancy frequently associated with the presence of the t(11;14) chromosomal translocation. By using a polymerase chain reaction (PCR) strategy to detect breakpoints within the major translocation cluster (MTC), an unexpectedly large product (about 1.1 kb by using first-round bcl-1/JH primers) has been identified in one out of 16 patients harbouring the t(11;14) translocation. Sequence analysis of the atypical PCR product, re-amplified and cloned with second-round primers, revealed a 459 bp portion corresponding exactly to the 3'-end segment of the MTC, followed by a sequence of 433 bp that lacked homology with any previously known sequence. PCR experiments using DNA from healthy donors identified that fragment as an extension of MTC fused, through a N-region of seven nucleotides, to the JH4 region of IgH gene. A computer-based search of the novel MTC portion aimed at detecting potential recombination motifs revealed the presence of several 4-bp sequences (5'-CCAG-3' or its complement 5'-CTGG-3'), one of them within seven nucleotides from the putative breakpoint, known to play a role in non-homologous recombination events at the Ig loci. The recognition of this novel breakpoint may have important implications for the diagnosis and detection of minimal residual disease in t(11;14)-positive lymphomas.

Expression pattern of MUM1/IRF4 in the spectrum of pathology of Hodgkin's disease

Biological and clinical studies have shown that Hodgkin's disease (HD) can be divided into two major categories, termed nodular lymphocyte predominance HD (NLP HD) and classic HD (CHD). Within CHD four subtypes have been distinguished: nodular sclerosis, mixed cellularity, lymphocyte rich and lymphocyte depletion. To refine the histogenesis of the pathological spectrum of HD, 75 CHD and 13 NLP HD were analysed for the expression pattern of MUM1/IRF4 (Multiple Myeloma-1/Interferon Regulatory Factor-4), a lymphocyte-specific member of the IRF family, that is expressed by late centrocytes and post-germinal centre (GC) B cells. MUM1 reacted with Hodgkin's and Reed-Sternberg (HRS) cells of all CHD cases (75/75 cases), with a moderate to strong staining intensity. Conversely, lymphocyte and histiocyte (L & H) cells, the putative tumour cells of NLP HD, were negative for MUM-1 expression (9/13 cases) or displayed a weak reactivity for the antigen in < 10% neoplastic cells (4/13 cases). With respect to HD microenvironment, NLP HD displayed numerous MUM1-positive T lymphocytes located in close proximity to L & H cells whereas, in CHD, MUM1-positive T lymphocytes appeared to be distributed randomly with no specific relationship with HRS cells. Overall, this study shows that MUM1 expression differs in L & H cells versus HRS cells, corroborating the notion that NLP HD and CHD represent different stages of B-cell differentiation. As MUM1-positive T lymphocytes form rosettes around tumour cells of NLP HD, but not of CHD, these data point also to differences in the microenvironment of NLP HD and CHD, and postulate an interactive role of MUM1-positive T lymphocytes with L & H cells.