Expressions of DNA topoisomerase I and II gene and the genes possibly related to drug resistance in human myeloma cells

In order to clarify the mechanism of drug resistance in human myeloma cells, we investigated the expressions of DNA topoisomerase I and topoisomerase II gene and the genes possibly related to drug resistance; multi-drug resistant gene 1 (MDR-1), glutathione S-transferase class pi gene (GST-pi), by Northern blotting. Myeloma cells in eight of 15 cases prior to chemotherapy expressed topoisomerase I mRNA considerably, while the expression of topoisomerase II mRNA was detected weakly in only one of 16 myeloma patients. There was not any correlation between expression of topoisomerase I mRNA and clinical drug resistance. Significant expression of MDR-1 mRNA and P-glycoprotein was not detected in 25 cases of multiple myeloma prior to chemotherapy and even after several courses of VAD (vincristine, adriamycin and dexamethasone) therapy by Northern blotting and immunostaining using monoclonal anti-P-glycoprotein antibody (MRK-16), respectively. On the other hand, 16 of 21 myeloma cases showed significant expression of GST-pi protein and GST-pi mRNA with the various strengths, but there was no apparent correlation between GST-pi mRNA expression and clinical response. Therefore these data suggest that expression of the genes we tested may not determine the level of drug resistance in multiple myeloma, but lower or no significant expression of topoisomerase II mRNA in most myeloma cells indicates the possibility that topoisomerase II inhibitors such as VP-16 and topoisomerase II-mediated cytotoxic drugs such as adriamycin, are not so effective for the treatment of multiple myeloma.

[Study on the therapy of multiple myelomas--initial induction therapy (MP, IFN alpha, steroid pulse) and maintenance therapy (VMP, MP continuous, VEP, MCNU)]

Untreated twenty patients of multiple myeloma were treated with the chemotherapy protocol as follows: Initial induction therapy;MP continuous or MP intermittent----IFN alpha----steroid pulse. Maintenance therapy;alkylating agents which have no cross resistance were used ((V) MP----(MP)----(V) EP----MCNU). Remission rate (CR+PR) after the initial MP therapy was 45%, and that after including IFN alpha and steroid pulse therapy was 50%, Fifty percent survival rate was almost as same as those reported previously (34M). Our protocol presented here was based on the idea that, initially, myeloma cells with proliferative activity could be affected by MP therapy, and subsequent IFN alpha therapy would have effect even on the residual myeloma cells. Serial checks of 3H-TdR uptake of myeloma cells during the therapy supported this idea. During the maintenance therapy, clinical responses to the initial induction therapy were not aggravated in the responded cases when evaluated by the variation of serum M-protein level. We propose that considering from a point of proliferative activity of myeloma cells is important for designing therapeutic protocols for multiple myeloma.

Homotypic cell aggregations of human myeloma cells with ICAM-1 and LFA-1 molecules

Some myeloma cells freshly isolated from bone marrow aspirates in human myelomas and some myeloma cell lines formed spontaneous cell aggregations in vitro (homotypic cell aggregations). In order to clarify the surface molecules involved in homotypic cell aggregations and physiological roles of these cell aggregations, we investigated the expressions of intercellular adhesion molecule 1 (ICAM-1) and lymphocyte function-associated antigen 1 (LFA-1) on 20 samples of freshly isolated myeloma cells and three myeloma cell lines and the effect of anti-ICAM-1 and anti-LFA-1 alpha antibodies on myeloma cell proliferation in vitro. All myeloma cells that we tested expressed ICAM-1 on their surface. Among them, myeloma cells that strongly coexpressed LFA-1 alpha, formed homotypic cell aggregates in vitro. These spontaneous cell aggregations were completely released by adding either anti-ICAM-1 or anti-LFA-1 alpha antibody. During short-term culture, spontaneous proliferation of myeloma cells in vitro and their proliferative responses to recombinant interleukin-6 (rIL-6) were not affected by pretreatment of myeloma cells with anti-ICAM-1 or anti-LFA-1 alpha antibody. Therefore these data suggest that homotypic cell aggregation of myeloma cells is mediated by ICAM-1 and LFA-1 molecules, but myeloma cell proliferation may not be modulated by these adhesion molecules during short-term cultures.

[A case of small cell carcinoma originating at the site of pneumoplication of giant bulla five years later]

A 64 year-old man was performed pneumoplication for his left-sided giant bulla on December 15, 1983. After five years, consciousness loss and right hemiplegia occurred. Brain CT revealed a cystic lesion with enhancement in the left occipital lobe. Brain biopsy disclosed metastatic small cell carcinoma. Lung biopsy showed the same histopathology, so primary lesion was considered to be from the site of the previous pneumoplication. Lung cancer associated with emphysematous bulla have been mostly characterized by tumor shadow or niveáu in the bulla. In this case, the postoperative infiltrating shadow of pneumoplication had made early diagnosis difficult.

Increased expression of the c-myc gene may be related to the aggressive transformation of human myeloma cells

Alteration and abnormal expression of the c-myc oncogene were investigated in human multiple myeloma. Human myeloma cells were highly purified (more than 95%) from bone marrow aspirates in 14 cases of advanced multiple myelomas and one case of plasma cell leukaemia. Southern blotting revealed that a rearranged configuration of c-myc gene was found in only one case of them, but this was a novel truncation of the gene in its coding exon II; a rearranged 3.4 kb band was detected by digestion with Xba I using c-myc exon II probe, but no rearranged band was found using exon III probe. In this case, the truncated c-myc allele was not transcribed; normal sized (2.4 kb) c-myc mRNA was markedly expressed, but no aberrant mRNA was detected. On the other hand, by Northern blotting, the nine cases, including the case with the rearranged c-myc gene, showed increased expression of normal sized (2.4 kb) c-myc mRNA. Elevated c-myc mRNA expressions were well related to the in vitro proliferation (3H-TdR uptake), but not to IL-6 response. Interestingly, extremely high expressions of c-myc mRNA were detected in two cases of aggressive myelomas, including the case with the rearranged c-myc gene, and in one of plasma cell leukaemia. These two cases of aggressive myelomas were the ones who showed the markedly high 3H-TdR uptakes, and had the common clinical features with the formation of an extramedullary mass and very short survival. These results suggest that the activation of c-myc gene could induce high proliferative activities and the subsequent aggressive transformation of myeloma cells.

Constitutive and interleukin-1 (IL-1)-inducible factors interact with the IL-1-responsive element in the IL-6 gene

The interleukin-6 (IL-6) promoter is rapidly and transiently activated with other cytokines, including IL-1, tumor necrosis factor, and platelet-derived growth factor, as well as phorbol esters and agents that increase intracellular cyclic AMP. In this study, we have investigated cis-acting regulatory elements and trans-acting factors responsible for IL-1-induced IL-6 gene expression. Studies on the 5' deletion mutants of the human IL-6 gene suggested that the IL-1-responsive element was mapped within the IL-6 promoter region (-180 to -123) which was homologous to the c-fos serum-responsive enhancer element. Gel retardation assay identified two types of nuclear factors that bound to this region, one constitutive and the other inducible. These two factors recognized a 14-base-pair (bp) palindromic sequence, ACATTGCACAATCT. Furthermore, three copies of this 14-bp palindrome conferred IL-1 responsiveness to the basal enhancerless IL-6 promoter, indicating that a 14-bp-dyad symmetry sequence was an IL-1-responsive element in the IL-6 gene.

A nuclear factor for IL-6 expression (NF-IL6) is a member of a C/EBP family

NF-IL6 is a nuclear factor that specifically binds to an IL1-responsive element in the IL-6 gene. In this study the gene encoding NF-IL6 has been cloned by direct screening of a lambda gt11 library using NF-IL6 binding sequence as a ligand. The full-length cDNA encoded a 345 amino acid protein with a potential leucine zipper structure and revealed a high degree of homology to a liver-specific transcriptional factor, C/EBP, at the C-terminal portion. The bacterial fusion protein bound to the CCAAT homology as well as the viral enhancer core sequences as in the case of C/EBP. Recombinant NF-IL6 activated the human IL-6 promoter in a sequence-specific manner. Southern blot analysis demonstrated the high-degree conservation of the NF-IL6 gene through evolution and the existence of several other related genes sharing the DNA-binding domain. NF-IL6 mRNA was normally not expressed, but induced by the stimulation with either LPS, IL-1 or IL-6. Interestingly, NF-IL6 was shown to bind to the regulatory regions for various acute-phase protein genes and several other cytokine genes such as TNF, IL-8 and G-CSF, implying that NF-IL6 has a role in regulation not only for the IL-6 gene but also for several other genes involved in acute-phase reaction, inflammation and hemopoiesis.

Effect of glucocorticoids on the biologic activities of myeloma cells: inhibition of interleukin-1 beta osteoclast activating factor-induced bone resorption

Regulatory effects of glucocorticoids (dexamethasone) on myeloma cells as well as bone resorption in multiple myeloma were investigated. Glucocorticoids significantly inhibited proliferation of myeloma cells, and decreased the messenger RNA (mRNA) expressions of interleukin-6 (IL-6) and secretory type immunoglobulin G (IgG). The inhibitory effects of glucocorticoids on myeloma cell proliferation could be due to the decreased expression of IL-6 mRNA, decreased IL-6 production, and thus suppression of autocrine growth by IL-6, which is an autocrine growth factor for myeloma cells as reported previously (Nature 332:83, 1988). Glucocorticoids also inhibited M-protein secretion by decreasing the levels of secretory type Ig mRNA. On the other hand, because IL-1 beta rather than lymphotoxin is considered to be a major osteoclast activating factor (OAF) produced by myeloma cells, and glucocorticoids decreased the expression of IL-1 beta mRNA and markedly suppressed the bone resorbing activity induced by IL-1 beta OAF in 45Ca-release bone resorption assay, it is suggestive that glucocorticoids could inhibit bone resorption induced by IL-1 beta OAF in multiple myeloma. Therefore, from these data it is concluded that glucocorticoids could be more effective chemotherapeutic agents in multiple myeloma than we expected, especially with regards to the inhibitory effects on proliferation and M-protein secretion from myeloma cells, as well as bone resorption by myeloma cells.

Sensitive inhibitory effect of interferon-alpha on M-protein secretion of human myeloma cells

The effects of interferon-alpha (IFN alpha) on in vitro proliferation and M-protein secretion in human myeloma cells were investigated. Human myeloma cells were purified from bone marrow aspirates in 12 multiple myeloma patients. Purified myeloma cells were cultured for 48 hours with IFN alpha at its lower concentrations (0.1 to 100 U/mL). The cells were then pulsed with 3H-TdR for the last 12 hours and 3H-TdR uptake was measured (in vitro proliferation). After 48-hour culture, supernatants were harvested and the amount of M-protein in these fluids were measured by enzyme-linked immunosorbent assay (ELISA) (in vitro M-protein secretion). In vitro M-protein secretions of myeloma cells were significantly suppressed even at 0.1 U/mL of IFN alpha, while 3H-TdR uptakes were not so suppressed until 10 or 100 U/mL of IFN alpha were added. The expressions of secretory immunoglobulin (Ig) mRNA of these myeloma cells were also selectively suppressed by IFN alpha. Furthermore, after IFN alpha had been administered intramuscularly, 3 to 6 x 10(6) U/d for at least 1 month, in vitro M-protein secretions of these myeloma cells were decreased compared with those before IFN alpha administration. Therefore, these results suggest that IFN alpha has more sensitive inhibitory effect on M-protein secretion of human myeloma cells rather than on myeloma cell proliferation.

BSF-2/IL-6 does not augment Ig secretion but stimulates proliferation in myeloma cells

Human myeloma cells were highly purified from bone marrow aspirates of 21 patients with advanced immunoglobulin G (IgG)-type multiple myeloma. B-cell stimulatory factor 2 (BSF-2)/interleukin-6 (IL-6) was originally characterized as a cytokine that can enhance immunoglobulin secretion from activated normal B cells and increase the expression of secretory-type Ig mRNA in these B cells, but that does not augment proliferation of activated B cells. However, recombinant IL-6 (rIL-6) could not enhance M-protein (IgG) secretion in freshly isolated myeloma cells in vitro but could augment proliferation of myeloma cells, although myeloma cells constitutively expressed IL-6 receptors. Furthermore, expression of secretory-type IgG (gamma-chain) mRNA in myeloma cells was not changed in the presence of IL-6. These results show that IL-6 is not an enhancing factor in Ig secretion from myeloma cells, and thus signal transduction through IL-6 in myeloma cells may be altered as opposed to activated B cells.

Interleukin-1 accelerates autocrine growth of myeloma cells through interleukin-6 in human myeloma

Recombinant interleukin 1 alpha (rIL-1 alpha) augmented proliferation of freshly isolated myeloma cells as well as B-cell stimulatory factor 2 (BSF-2)/interleukin-6 (IL-6). Recombinant IL-1 alpha-induced proliferation was partially inhibited by anti-IL-6 antibody. In the culture supernatants of rIL-1 alpha-stimulated myeloma cells, IL-6 activities, which were measured by using an IL-6-dependent murine hybridoma clone, MH60.BSF2, were increased, when compared with those in the culture supernatants of nonstimulated myeloma cells. Furthermore, IL-6 messenger RNA (mRNA) expression was also augmented in IL-1 alpha-stimulated myeloma cells. Therefore rIL-1 alpha stimulates myeloma cells to produce IL-6, which consequently augments proliferation of myeloma cells. Thus, IL-1 can accelerate autocrine growth of myeloma cells through IL-6.

Interleukin-1 beta rather than lymphotoxin as the major bone resorbing activity in human multiple myeloma

Human myeloma cells were purified from bone marrow aspirates from four patients having advanced myeloma, including one with common acute lymphoblastic leukemia antigen-positive myeloma. All of these myelomas had marked bone lytic lesions. From the culture supernatants of these purified myeloma cells, bone-resorbing activities were significantly revealed by 45Ca-release bone resorption assay, and IL-1 activities were also detected by IL-1 bioassay (mouse thymocyte comitogenic assay). Sandwich enzyme immunoassay for IL-1 alpha or IL-1 beta revealed that IL-1 beta was responsible for IL-1 activity of these culture supernatants. Furthermore, the bone resorbing activities of these culture supernatants were completely neutralized by pretreatment of anti-IL-1 beta, but not anti-IL-1 alpha antibody. By Northern blot analysis, IL-1 beta mRNA was identified from these myeloma cells. Therefore, it is concluded that myeloma cells produce IL-1 beta, which acts as bone-resorbing activity in multiple myeloma.

[A case of refractory multiple myeloma demonstrating a relationship between the progression of the disease and in vitro myeloma cells activity]

In vitro proliferation (3H-TdR-uptake) and M-protein secretion rate by highly purified myeloma cells from bone marrow aspirates were examined serially to evaluate the progression of multiple myeloma in a patient who was refractory to conventional alkylating agents. Following the administration of IFN-alpha, serum M-protein decreased significantly, with the reduced in vitro spontaneous M-protein secretion rate from the separated myeloma cells. Similarly, when IFN-alpha as low as 10 u/ml was added in vitro, it also suppressed M-protein secretion from myeloma cells of this patient, suggesting that, the observed decrease of serum M-protein was due to diminished M-protein secretion by the myeloma cells themselves, as well as the reduction of the tumor cell burden. On the other hand the in vitro 3H-TdR uptake by the myeloma cells increased markedly with the decrease in the M-protein secretion rate. Five months after the initiation of IFN-alpha treatment, tumor formation at the lumbar vertebrae occurred when serum M-protein level was still low, followed by a bone marrow relapse. These results suggest that serial assessments of proliferation and M-protein secretion potential of myeloma cells in vitro can be helpful in predicting the progression of multiple myeloma.

Altered cytokine activities are related to the suppression of synthesis of normal immunoglobulin in multiple myeloma

The content of peripheral blood B cells (B1+) was reduced in patients of multiple myeloma (MM) and not in those with benign monoclonal gammopathy (BMG) compared to normal donors (P less than 0.01). This observation correlated with the suppression of synthesis of normal immunoglobulin (Ig) in MM. Thus, cytokine activities regulating the proliferation of normal mature B cells, such as B cell stimulatory factor 1 (BSF-1)/interleukin 4 (IL-4), B cell growth inhibitory factor (BIF) and IL-2 in peripheral blood T cells, and IL-1 in peripheral blood adherent cells, were investigated in patients with BMG (n = 7) and MM (n = 28). All patients of MM having a marked suppression of synthesis of all other normal Ig, had significantly lower levels of BSF-1 activity and inversely higher levels of BIF activity than those of normal donors. However, patients with BMG having no suppression of synthesis of normal Ig had BSF-1 and BIF activities similar to normal donors. There was no significant difference in IL-1 and IL-2 activities between both normal donors and BMG versus MM patients. These data show that in MM altered cytokine activities correlate with suppression of synthesis of normal Ig.

Heterogenous response of B cell chronic lymphocytic leukaemia (B-CLL) cells to anti-human IgM antibody (anti-mu) and B cell stimulatory factor 1 (BSF-1)

B cell chronic lymphocytic leukaemia (B-CLL) cells from seven patients were examined for 3H-TdR uptake with anti-human IgM antibody (anti-mu) and B cell stimulatory factor 1 (BSF-1)/IL-4. B-CLL cells from one patient could proliferate with anti-mu plus BSF-1, but not with BSF-1 alone. B-CLL cells from two patients responded to BSF-1 alone; one could proliferate more by adding anti-mu, but the proliferation of the other cells was inhibited by adding anti-mu. On the other hand, B-CLL cells from the other four patients responded neither to anti-mu nor to anti-mu plus BSF-1. Surface densities of membrane IgM of B-CLL cells were also analysed by fluorescence activated cell sorter (FACS), but there was no correlation between proliferative response (DNA synthesis) of B-CLL cells to anti-mu and densities of surface membrane IgM. These results show that there is a functional heterogeneity of B-CLL cells with regard to proliferative response to anti-mu and BSF-1.

Genomic structure of the murine IL-6 gene. High degree conservation of potential regulatory sequences between mouse and human

The genomic clone of mouse IL-6 was isolated and compared with the human IL-6 gene. The comparison revealed that the mouse IL-6 consists of five exons and four introns and that the overall organization is similar to that of the human IL-6 gene although the third intron is about 2 kb longer. The sequence similarity in the coding region is about 60%, whereas the 3'-untranslated region and the first 300-bp sequence of the 5'-flanking region are highly conserved (greater than 80%). Several sequence blocks with high homology are also found in the introns. Furthermore, sequences similar to transcriptional enhancer elements such as the c-fos serum responsive element and the consensus sequences for cAMP induction, activator protein 1 binding, and the glucocorticoid receptor binding are identified within the highly conserved 5'-flanking regions of the genes from the two species. These sequences may play an important role in transcriptional activation of the IL-6 gene.

Genomic structure of the murine IL-6 gene. High degree conservation of potential regulatory sequences between mouse and human

The genomic clone of mouse IL-6 was isolated and compared with the human IL-6 gene. The comparison revealed that the mouse IL-6 consists of five exons and four introns and that the overall organization is similar to that of the human IL-6 gene although the third intron is about 2 kb longer. The sequence similarity in the coding region is about 60%, whereas the 3'-untranslated region and the first 300-bp sequence of the 5'-flanking region are highly conserved (greater than 80%). Several sequence blocks with high homology are also found in the introns. Furthermore, sequences similar to transcriptional enhancer elements such as the c-fos serum responsive element and the consensus sequences for cAMP induction, activator protein 1 binding, and the glucocorticoid receptor binding are identified within the highly conserved 5'-flanking regions of the genes from the two species. These sequences may play an important role in transcriptional activation of the IL-6 gene.

Separation of human myeloma cells from bone marrow aspirates in multiple myeloma and their proliferation and M-protein secretion in vitro

Human myeloma cells were purified from bone marrow aspirates from patients with multiple myeloma (MM) by Percoll discontinuous density-gradient centrifugation, E rosette formation and treatment with antimyelomonocytic antibody (Leu M1), plus complement. Thus, the purified cell fraction consisted of greater than 90% myeloma cells, even when as little as 15% myeloma cells were contained in bone marrow mononuclear cell fraction, determined by morphological and immunologic examinations. With highly purified myeloma cells from 29 patients with IgG type MM, biologic characteristics such as spontaneous proliferation (3H-TdR uptake) and M-protein secretion rate in vitro were evaluated. Both activities varied among patients within stage I and III, and a 3H-TdR uptake of 255-24, 132 cpm/4 x 10(4) cells, and an M-protein secretion rate of 9 to 72 pg/cell/day, respectively, were recorded. However, in each patient, there was no correlation between 3H-TdR uptake and M-protein secretion rate. These results thus suggest that 3H-TdR uptake and M-protein secretion rate of highly purified myeloma cells are independent biologic parameters, not associated with the clinical stages, and the purification of myeloma cells we describe can contribute to further studies on the biologic characteristics and to understanding of the pathophysiology involved in MM.

Decrease in BSF-2/IL-6 response in advanced cases of multiple myeloma

Human myeloma cells freshly isolated from 40 patients with IgG multiple myeloma (MM, 10 in stage I and 30 in stage III), were cultured for 48 hours with recombinant B cell stimulatory factor 2 (rBSF-2)/interleukin-6 (IL-6), which is considered a major growth factor for myeloma cells. Uptake of 3H-thymidine by these purified myeloma cells was measured, and BSF-2 response was evaluated by stimulation index and delta cpm induced by rBSF-2. Myeloma cells from cases in stage I responded to rBSF-2 better than those in stage III. Moreover rBSF-2 responders also showed better response to chemotherapy. Therefore, these results suggest that in vitro response of myeloma cells to BSF-2 correlates with disease progression and clinical response in patients of MM.

Autocrine generation and requirement of BSF-2/IL-6 for human multiple myelomas

Human B cell stimulatory factor 2 (BSF-2) was originally characterized and isolated as a T cell-derived factor that caused the terminal maturation of activated B cells to immunoglobulin-producing cells. Molecular cloning of the complementary DNA predicts that BSF-2 is a protein of relative molecular mass (Mr) 26,000 similar or identical to interferon beta 2, hybridoma plasmacytoma growth factor and hepatocyte stimulating factor. IL-6 has been proposed as a name for this molecule. It is now known that BSF-2 has a wide variety of biological functions and that its target cells are not restricted to normal B cells. Responses are also seen in T cells, plasmacytomas, hepatocytes, haematopoietic stem cells, fibroblasts and rat phoeochromocytoma, PC12 (Satoh, T. et al., manuscript in preparation). Of particular interest to this report is that human BSF-2 is a potent growth factor for murine plasmacytomas and hybridomas. This observation suggested to us that constitutive expression of BSF-2 or its receptor could be responsible for the generation of human myelomas. In this study we report that myeloma cells freshly isolated from patients produce BSF-2 and express its receptors. Moreover, anti-BSF-2 antibody inhibits the in vitro growth of myeloma cells. This is direct evidence that an autocrine loop is operating in oncogenesis of human myelomas.

Kininase and anti-inflammatory activities of acid carboxypeptidase from Penicillium janthinellum

The acid carboxypeptidase from Penicillium janthinellum catalyzed the rapid release of arginine, and the slow release of phenylalanine, proline, serine and glycine from the carboxy-terminal of bradykinin at pH 4.15 to 4.8. Anti-inflammatory activity of the acid carboxypeptidase seems to suggest that the enzyme hydrolyzed bradykinin in vivo.

Action of crystalline acid carboxypeptidase from Penicillium janthinellum

Acid carboxypeptidase (EC 3.4.12.-) crystallized from culture filtrate of Penicillium janthinellum has been investigated for its use in carboxy-terminal sequence determination of Z-Gly-Pro-Leu-Gly, Z-Gly-Pro-Leu-Gly-Pro, angiotensin I, native lysozyme, native ribonuclease T1, and reduced S-carboxy-methyl-lysozyme. The examination indicated that proline and glycine were liberated from Z-Gly-Pro-Leu-Gly-Pro. At high enzyme concentration, the enzyme catalyzed complete sequential release of amino acids from the carboxy-terminal leucine to the amino-terminal aspartic acid of angiotensin I. The enzyme released the carboxy-terminal leucine from native lysozyme, however, no release of the threonine from native ribonuclease T1 was observed after a prolonged period of incubation with the enzyme. The sequence of the first nine carboxy-terminal residues of denatured lysozyme, leucine, arginine, S-carboxymethyl-cysteine, glycine, arginine, isoleucine, tryptophane, alanine, and glutamine, could be deduced unequivocally from a time release plot of an incubation mixture with the enzyme.