Comparison of native E. coli and PEG asparaginase pharmacokinetics and pharmacodynamics in pediatric acute lymphoblastic leukemia

Asparaginase (ASP) is used routinely in frontline clinical trials for the treatment of childhood acute lymphoblastic leukemia (ALL). The goals of this study were to assess the pharmacokinetics and pharmacodynamics of ASP and to mathematically model the dynamics between ASP and asparagine (ASN) in relapsed ALL. Forty children were randomized to receive either native or polyethylene glycolated (PEG) Escherichia coli ASP during reinduction therapy. Serial plasma ASP and ASN, cerebrospinal fluid (CSF) ASN, and serum anti-ASP antibody samples were collected. The ASP clearance was higher (P = 0.001) for native vs. PEG ASP. Patients with antibodies to PEG ASP had faster PEG ASP clearance (P = 0.004) than did antibody-negative patients. Patients who were positive for antibodies had higher CSF ASN concentrations than did those who were negative (P = 0.04). The modeling suggests that by modifying dosages, comparable ASN depletion is achievable with both preparations. At relapse, there were significant pharmacokinetic and pharmacodynamic differences attributable to ASP preparation and antibody status.

Genome-wide analysis of DNA copy number alterations and gene expression in gastric cancer

Genomic copy number aberrations (CNAs) are believed to play a major role in the development and progression of human cancers. Although many CNAs have been reported in gastric cancer, their genome-wide transcriptional consequences are poorly understood. In this study, to reveal the impact of CNAs on genome-wide expression in gastric cancer, we analysed 30 cases of gastric cancers for their CNAs by array comparative genomic hybridization (array CGH) and 24 of these 30 cases for their expression profiles by oligonucleotide-expression microarray. We found that with the application of laser microdissection, most CNAs were detected at higher frequency than in previous studies. Notably, gain at 20q13 was detected in almost all cases (97%), suggesting that this may play an important role in the pathogenesis of gastric cancer. By comparing the array CGH data with expression profiles of the same samples, we showed that both genomic amplification and deletion strongly influence the expression of genes in altered genomic regions. Furthermore, we identified 125 candidate genes, consisting of 114 up-regulated genes located in recurrent regions (>10%) of amplification and 11 down-regulated genes located in recurrent regions of deletion. Up-regulation of several candidate genes, such as CDC6, SEC61G, ANP32E, BYSL and FDFT1, was confirmed by immunohistochemistry. Interestingly, some candidate genes were localized at genomic loci adjacent to well-known genes such as EGFR, ERBB2 and SMAD4, and concordantly deregulated by genomic alterations. Based on these results, we propose that our list of candidate genes may contain novel genes involved in the pathogenesis of advanced gastric cancer.

Genome-wide microRNA expression profiling in renal cell carcinoma: significant down-regulation of miR-141 and miR-200c

We investigated expression profiles of microRNA (miRNA) in renal cell carcinoma [clear cell carcinomas (CCC) and chromophobe renal cell carcinomas (ChCC)] and in normal kidneys by using a miRNA microarray platform which covers a total of 470 human miRNAs (Sanger miRBase release 9.1). Unsupervised hierarchical cluster analysis revealed that CCC and ChCC were separable and that no subgroups were identified in CCCs. We found that 43 miRNAs were differentially expressed between CCC and normal kidney, of which 37 were significantly down-regulated in CCC and the other 6 were up-regulated. We also found that 57 miRNAs were differentially expressed between ChCC and normal kidney, of which 51 were significantly down-regulated in ChCC and the other 6 were up-regulated. Together, these observations indicate that expression of miRNAs tends to be down-regulated in both CCC and ChCC compared with normal kidney. We observed that miR-141 and miR-200c were the most significantly down-regulated miRNAs in CCCs. Indeed, in all cases of CCC analysed, both miR-141 and miR-200c were down-regulated in comparison with normal kidney. Microarray data and quantitative RT-PCR showed that these two miRNAs were expressed concordantly. TargetScan algorithm revealed that ZFHX1B mRNA is a hypothetical target of both miR-141 and -200c. We established by quantitative RT-PCR that, in CCCs in which miR-141 and miR-200c were down-regulated, ZFHX1B, a transcriptional repressor for CDH1/E-cadherin, tended to be up-regulated. Furthermore, we found that overexpression of miR-141 and miR-200c caused down-regulation of ZFHX1B and up-regulation of E-cadherin in two renal carcinoma cell lines, ACHN and 786-O. On the basis of these findings, we suggest that down-regulation of miR-141 and miR-200c in CCCs might be involved in suppression of CDH1/E-cadherin transcription via up-regulation of ZFHX1B.

Genotyping of the cagA gene of Helicobacter pylori on immunohistochemistry with East Asian CagA-specific antibody

The cytotoxin-associated antigen A (CagA) of Helicobacter pylori prevalent in East Asian countries, where the mortality rate due to gastric cancer is high, has been reported to be structurally different from that in Western countries, where the gastric cancer mortality rate is relatively low. Based on the structural features of the EPIYA motifs located at the carboxyl terminal of the protein, CagA was subdivided into two types: East Asian CagA and Western CagA. A recent study suggested that immunohistochemistry with anti-East Asian-specific antibody (alpha-EAS Ab), which was specifically immunoreactive with East Asian CagA but not with Western CagA, may be useful for diagnosis of the cagA genotype. To further evaluate the value of this diagnostic method in terms of sensitivity, specificity, and accuracy, 143 gastric biopsy specimens with alpha-EAS Ab were analyzed on immunohistochemistry and compared with the sequencing of the cagA gene. It was found that diagnosis of the cagA genotype of H. pylori on immunohistochemistry using the alpha-EAS Ab was highly sensitive (sensitivity 93.2%) and specific (specificity 72.7%), suggesting that immunohistochemical diagnosis of the cagA genotype is useful for diagnosis of the cagA genotype.

Arpp/Ankrd2, a member of the muscle ankyrin repeat proteins (MARPs), translocates from the I-band to the nucleus after muscle injury

Ankyrin-repeat protein with a PEST motif and a proline-rich region (Arpp), also designated as Ankrd2, is a member of the muscle ankyrin repeat proteins (MARPs), which have been proposed to be involved in muscle stress response pathways. Arpp/Ankrd2 is localized mainly in the I-band of striated muscle. However, it has recently been reported that Arpp/Ankrd2 can interact with nuclear proteins, such as premyelocytic leukemia protein (PML), p53 and YB-1 in vitro. In this study, to determine whether nuclear accumulation of Arpp/Ankrd2 actually occurs, we performed an immunohistochemical investigation of gastrocnemius muscles that had been injured by injection of cardiotoxin or contact with dry ice. We found that Arpp/Ankrd2 accumulated in the nuclei of myofibers located adjacent to severely damaged myofibers after muscle injury. Double-labeled immunohistochemistry revealed that Arpp/Ankrd2 accumulated in the nuclei of sarcomere-damaged myofibers. Furthermore, we found that Arpp/Ankrd2 tended to be localized in euchromatin where genes are transcriptionally activated. Based on these findings, we suggest that Arpp/Ankrd2 may translocate from the I-band to the nucleus in response to muscle damage and may participate in the regulation of gene expression.

A phase I study of clofarabine in combination with cyclophosphamide and etoposide: A new regimen in pediatric patients with refractory or relapsed acute leukemia

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Background: Clofarabine is a promising new agent in the treatment of childhood leukemia as evidenced by single agent activity in previous phase I and II studies. We conducted a pilot phase I study of clofarabine used in combination with cyclophosphamide and etoposide to determine the maximum tolerated dose (MTD) and dose limiting toxicities (DLT). Methods: Patients between 1 and 21 years old with relapsed or refractory acute lymphoblastic leukemia (ALL) and acute myelogenous leukemia (AML) were enrolled. A standard 3+3 design was followed to determine the safe dose when used in combination. All drugs were administered by IV infusion daily for 5 consecutive days in induction and 4 days in consolidation. Patients received up to 2 induction cycles depending on the response, followed by consolidation cycles (maximum of 8 total cycles). The initial doses (cohort 1) were as follows: clofarabine: 20 mg/m2/day, etoposide 75 mg/m2/day and cyclophosphamide 340 mg/m2/day. Once etoposide and cyclophosphamide were escalated to their target dose (100 mg/m2/day and 440 mg/m2/day respectively in cohort 3), clofarabine was then increased to 30 mg/m2/day in cohorts 4 and would be increased to 40 mg/m2/day in cohort 5. Results: Thirteen patients (10 ALL; 3 AML) were enrolled in the first 4 dose cohorts to this date. The median number of prior regimens was 2. Response data (based on investigator assessment) are available for the first 8 patients: 6 patients (including 1 patient with AML) achieved either complete remission (CR) or complete remission without platelet recovery (CRp), for an overall response rate of 75%. Four patients proceeded to HSCT. One patient in cohort 4 experienced a DLT which resolved (grade 3 elevation of lipase) and possible veno-occlusive disease leading to cohort expansion. Common toxicities noted include febrile neutropenia and fever. Conclusions: The phase I study is ongoing until determination of MTD for this combination but these early results indicate that this combination shows significant activity in children with refractory or relapsed acute leukemias and is well-tolerated.

No significant financial relationships to disclose.

Immunohistochemical diagnosis of the cagA-gene genotype of Helicobacter pylori with anti-East Asian CagA-specific antibody

Cytotoxin-associated antigen A (CagA) protein produced by Helicobacter pylori is proposed to be associated with the pathogenesis of gastric cancer as well as gastritis and gastroduodenal ulcer. It has been reported that the CagA of H. pylori widespread in East Asian countries, where the mortality rate due to gastric cancer is high, is structurally different from that in Western countries, where the gastric cancer mortality rate is relatively low. In this study, we generated an antibody, East Asian CagA-specific antibody (alpha-EAS Ab), which is specifically immunoreactive with East Asian CagA but not with Western CagA. The CagA was immunohistochemically detected at the surface of the gastric mucosa. Interestingly, positive immunoreactivity was also detected in the nucleus and cytoplasm of the infected gastric epithelium, suggesting that CagA may play some pathogenic role in both the nucleus and cytoplasm. Immunohistochemistry of 47 gastric biopsy specimens detected East Asian CagA-positive H. pylori in 43 cases. In 46 of the 47 cases examined, the data obtained by immunohistochemistry were completely consistent with those obtained by sequencing of the cagA gene of the isolated strain, suggesting that our immunohistochemical method is reliable and useful for diagnosis of the cagA genotype.

Aortic root subadventitial hematoma

A 51-year-old woman was operated on for aortic valve regurgitation 3 months after experiencing chest tightness awakening her from sleep. Intraoperative findings included turbid dark brown pericardial fluid and a nipple-shaped protrusion on the external aspect of the noncoronary sinus of Valsalva. Histologically, the lesion was enclosed by intact media and adventitia, and represented an organized hematoma. Dilated venules noted adjacent to the lesion were suggestive of an intramural hemangioma. The etiology of this lesion is unclear, but it might be an unusual type of intramural hematoma (IMH) and gives us a hint of an origin of IMH.

ARPP protein is selectively expressed in renal oncocytoma, but rarely in renal cell carcinomas

We have recently isolated a gene, Ankyrin-repeated protein with a proline-rich region (ARPP), that is highly expressed in the skeletal and cardiac muscle. Our previous immunohistochemical analysis revealed that ARPP expression was augmented in rhabdomyosarcoma but scarcely detectable in leiomyosarcoma, showing that ARPP is a useful marker for rhabdomyosarcoma. In the present study, we generated the anti-ARPP monoclonal antibody, YAS11, immunoreactive with the N-terminal region (amino-acids residues 1-145) of the ARPP protein. Further, we immunohistochemically analyzed 100 renal tumors including 14 oncocytomas, and 86 renal cell carcinomas (RCCs). We found that ARPP was highly expressed in 12 of the 14 (85.7%) oncocytomas, but was detectable in only four of the 86 (4.7%) RCCs. Interestingly, ARPP was not detected in any of 11 chromophobe RCCs, suggesting that ARPP may be useful for differential diagnosis between oncocytoma and chromophobe RCC. Furthermore, we found that ARPP was selectively expressed in part of the distal renal tubule in normal kidney. Immunoelectron microscopy with anti-ARPP antibody revealed that ARPP was localized in mitochondria and nuclei in both the normal distal renal tubule and oncocytoma, suggesting that oncocytoma may be derived from the distal nephron, and probably from part of the distal renal tubule.

Upregulated expression of cardiac ankyrin-repeated protein in renal podocytes is associated with proteinuria severity in lupus nephritis

Cardiac ankyrin-repeated protein (CARP) was originally identified as a protein specifically expressed in cardiomyocytes, but has recently been found to be upregulated in some muscle diseases including muscular dystrophy and myopathy, suggesting that CARP may be induced in some pathologic conditions. In this study, we immunohistochemically analyzed 69 renal biopsy samples from patients with glomerular diseases and 2 individuals with normal kidney. We found that CARP was expressed in renal podocytes at a high level in 10 of 13 cases of crescentic glomerulonephritis, 7 of 19 cases of diabetic nephropathy, and 12 of 20 cases of lupus nephritis, although it was not expressed in endocapillary glomerulonephritis, minimal change disease, thin basement membrane disease, membranous glomerulonephritis, and normal kidney. Interestingly, in lupus nephritis, CARP expression tended to be induced in cases exhibiting nephrotic syndrome, but less so in cases without nephrotic syndrome, suggesting that CARP expression is correlated with the severity of proteinuria. Furthermore, we found that CARP was not expressed in membranous glomerulonephritis but evidently expressed in most cases of membranous lupus nephritis. Although membranous glomerulonephritis and membranous lupus nephritis are sometimes morphologically indistinguishable, it is suggested that their pathologic mechanisms differ. Therefore, we propose that examination of CARP expression is useful for precise differential diagnosis of membranous glomerulonephritis and membranous lupus nephritis.

Extracellular signal-regulated protein kinase is activated in cervical intraepithelial neoplasms but inactivated in invasive cervical carcinoma

The extracellular signal-regulated protein kinase (ERK) signaling pathway has been reported to play important roles in cell growth in various neoplasms. The purpose of the present study was to immunohistochemically analyze the phosphorylation status (activity) of ERK in 24 cases of cervical carcinoma using an antiphosphorylated ERK antibody (alphap-ERK Ab) that specifically recognizes the phosphorylated form of ERK (p-ERK). In normal cervical epithelium, p-ERK was found to be confined to basal cells that were negative for Ki-67, suggesting that ERK was not activated in proliferating normal cervical epithelium. In cervical intraepithelial neoplasms (CIN), increased abnormal parabasal cells were positive for both p-ERK and Ki-67, suggesting that ERK activation in CIN may be involved in tumor cell proliferation. In contrast, it was found that, in invasive cervical carcinomas, almost all the carcinoma cells were positive for Ki-67 but negative for p-ERK, suggesting that, in contrast to many other types of cancers, the ERK signaling pathway is downregulated in invasive cervical carcinoma. These findings suggest that the phosphorylation status of ERK differs between CIN and invasive carcinomas, and that downregulation of the ERK signaling pathway may contribute to transformation of CIN to invasive cervical carcinomas.

Successive clinical trials for childhood acute myeloid leukemia at St Jude Children's Research Hospital, from 1980 to 2000

Despite substantial progress in the management of childhood acute myeloid leukemia (AML), only about 50% of patients are cured by intensive chemotherapy. The long-term results of clinical trials may reveal principles that can guide the development of future therapy. From 1980 to 2000, 251 patients <15 years of age with newly diagnosed AML were enrolled on one of the five consecutive St Jude AML studies. The median age of the 128 boys and 123 girls was 6.2 years; 193 were white, 45 black, and 13 of other racial groups. With the exception of one protocol (AML-83), outcomes improved in general over the two decades. The estimated 5-year event-free survival (+/-s.e.) was 30.8+/-5.6% for AML-80; 11.1+/-4.3% for AML-83; 35.9+/-7.4% for AML-87; 43.5+/-6.2% for AML-91; and 45.0+/-11.1% for AML-97. Resistant or relapsed AML caused the great majority of treatment failures. Increasing the intensity of chemotherapy (AML-87) did not improve outcome, partially because of toxicity, nor did prolonging postremission therapy by adding sequential myeloablative (AML-80) or nonmyeloablative (AML-83) chemotherapy cycles. We conclude that subtype-specific therapies are needed to replace the 'one size fits all' strategy of the past two decades.

Overt testicular disease at diagnosis of childhood acute lymphoblastic leukemia: lack of therapeutic role of local irradiation

To assess the prognosis of overt testicular disease at diagnosis of acute lymphoblastic leukemia, and any therapeutic role of irradiation for this involvement, we reviewed the data of 811 boys treated on St Jude studies Total X--XI (early period) and Total XII-XIV (recent period). In all, 19 boys (2.3%) had testicular disease at diagnosis. In the early period, patients with testicular leukemia had a poorer overall survival (OS) (P=0.003), event-free survival (EFS) (P=0.064), and higher cumulative incidence of relapse (P=0.041) than did other patients. During the recent period, patients with and without overt testicular leukemia did not differ in OS (P=0.257), EFS (P=0.102), or cumulative incidence of relapse (P=0.51). In a multivariate analysis, OS was lower for patients with testicular disease than for those without the involvement in the early period (P=0.047) but not in the recent one (P=0.75). Both patients who received irradiation for residual testicular disease at the end of induction subsequently died of leukemia. Of the other 17 patients who did not receive irradiation, only one developed testicular relapse in combination with bone marrow relapse. In conclusion, the prognostic impact of overt testicular disease has diminished. Irradiation appears to provide no survival advantage to this patient population.

Involvement of CD14 in lipopolysaccharide- induced liver injury in mice pretreated with Propionibacterium acnes

OBJECTIVE

The aim of this study was to elucidate the role of CD14 in the Propionibacterium acnes-lipopolysaccharide (LPS) system.

METHODS AND RESULTS

CD14 transgenic mice (M14M), which expressed heterotopic CD14 and showed decreased responses to LPS in vivo, were used. Seven days after priming, the size of granulomas induced by an intraperitoneal administration of P. acnes in the M14M mice was smaller than that in the nontransgenic mice. The number of CD14-positive cells in granulomas was also decreased in the M14M mice compared to the nontransgenic mice. An LPS challenge induced apoptotic and necrotic changes in hepatocytes in the nontransgenic mice but not in the M14M mice. Seven days after priming, tumor necrosis factor-alpha expression was found in monocytic cells in granulomas and Kupffer cells in the nontransgenic mice and was significantly upregulated after LPS injection, whereas the expression was very weak in these cells in the M14M mice.

CONCLUSIONS

CD14 plays a role in the P. acnes-LPS system in both priming and induction phases.

Expression of splice variants of the human ADAM15 gene and strong interaction between the cytoplasmic domain of one variant and Src family proteins Lck and Hck

OBJECTIVE

The aim of the present study was to show variant species of ADAM15 and unique Src homology 3 (SH3)-binding motifs, which strongly bound Src family proteins compared with ADAM15.

METHODS AND RESULTS

RT-PCR using primers for the cytoplasmic domain revealed the presence of different species, designated ADAM15v1 and ADAM15v2, which had characteristic SH3-binding class I and class II motifs. The mRNA of ADAM15v1 and ADAM15v2 was mainly found in peripheral blood mononuclear cells, T lymphocytes and monocytic cell lines. ADAM15v2 protein interacted more strongly with the Src family proteins Lck and Hck than did ADAM15 protein, as examined by pull-down analysis and immunoprecipitation followed by immunoblot analysis. The binding with Lck and Hck was enhanced by the phosphorylation of ADAM15v2 protein.

CONCLUSIONS

These results suggest that the cytoplasmic domain of ADAM15v2 strongly interacts with Lck and Hck and regulates leukocyte function.

Roles of CD14 in LPS-induced liver injury and lethality in mice pretreated with Propionibacterium acnes

The mechanism of the liver damage and lethality in Propionibacterium acnes (P. acnes)-LPS system remains obscure. To examine the role of CD14 in the system, M14M mice, in which CD14 was expressed heterotopically under the control of the metallothionein promoter were used. The production of soluble CD14 (sCD14) was increased by both P. acnes - priming and LPS challenge (1 microg per mouse) in both nontransgenic and M14M mice, although the plasma level was much higher in M14M nontransgenic than mice. The size of granulomas induced by an intraperitoneal administration of P. acnes in M14M mice 7 days after priming was smaller than that in nontransgenic mice. An LPS challenge induced apoptotic and necrotic changes in hepatocytes in nontransgenic mice but not in M14M mice. The challenge dose resulted in almost 90% lethality in nontransgenic mice but not in M14M mice 24h after challenge. TNF-alpha, IFN-gamma, IL-12, IL-18 and inducible nitric oxide synthase (iNOS) mRNA expressions produced by LPS challenge in M14M mice were low compared with those in nontransgenic mice. IL-18 mRNA expression was upregulated in P. acnes-primed nontransgenic mice but not in M14M mice. These results suggest that the high sCD14 concentration may account for less marked liver damage in M14M mice. Increase in the challenge dose of LPS (2 microg per mouse) resulted in increased lethality of M14M mice without liver damage. The levels of endothelial cell leukocyte adhesion molecule (ELAM)-1 mRNA expression in several organs in M14M mice 1-3h after LPS challenge were, however, lower than those in nontransgenic mice. The high sCD14 concentration may stimulate endothelial cell activation, which may account for lethality without liver damage in M14M mice. Thus, CD14 is involved in both the priming and induction phases as well as lethality in P. acnes-LPS system.

Clinical significance of minimal residual disease in childhood acute lymphoblastic leukemia after first relapse

Using flow cytometric techniques capable of detecting 0.01% leukemic cells, we prospectively studied minimal residual disease (MRD) in patients with acute lymphoblastic leukemia (ALL) after first relapse. At the end of remission reinduction, 41 patients had a bone marrow sample adequate for MRD studies; 35 of these were in morphologic remission. Of the 35 patients, 19 (54%) had MRD >/=0.01%, a finding that was associated with subsequent leukemia relapse. The 2-year cumulative incidence of second leukemia relapse was 70.2+/-12.3% for the 19 MRD-positive patients and 27.9+/-12.4% for the 16 MRD-negative patients (P=0.008). Among patients with a first relapse off therapy, 2-year second relapse rates were 49.1+/-17.8% in the 12 MRD-positive and 0% in the 11 MRD-negative patients (P=0.014); among those who received only chemotherapy after first relapse, the 2-year second relapse rates were 81.5+/-14.4% (n=12) and 25.0+/-13.1% (n=13), respectively (P=0.004). Time of first relapse and MRD were the only two significant predictors of outcome in a multivariate analysis. We conclude that MRD assays should be used to guide the selection of postremission therapy in patients with ALL in first relapse.

Pinhole rupture of aortic root aneurysm with severe atherosclerotic change

We report two cases of the rupture of calcified aortic root aneurysms that were successfully treated by emergency operations. One patient underwent Bentall's operation, and for the other, we performed a valve-sparing operation. Because their aneurysms revealed pear-like configurations with aortic regurgitation, the findings were consistent with annuloaortic ectasia (AAE). However, both cases were unlike typical AAE in that the aortic walls showed severe atherosclerotic change, with little sign of cystic medial necrosis. It was very interesting that each rupture point was a very small pinhole originating from one of the atherosclerotic ulcers.

The Roles of Soluble Osteopontin Using Osteopontin-Transgenic Mice in vivo: Proliferation of CD4+ T Lymphocytes and the Enhancement of Cell-Mediated Immune Responses

We generated transgenic mice expressing osteopontin (OPN) under the control of the alpha(1)-antitrypsin promoter. These mice (OPN-T mice) expressed OPN mRNA in liver and kidney, and released a large amount of plasma OPN, which increased after stimulation with turpentine oil. Before sensitization, the number of CD4+ T cells in lymph nodes was significantly higher in OPN-T than nontransgenic mice, and that in spleen was slightly higher, whereas that of CD8+ T cells was no different between OPN-T and nontransgenic mice. After sensitization, the CD4+ T cell numbers in spleen increased significantly, while there were almost no changes in the CD8+ T cells in lymph nodes and spleen. The intensity of contact hypersensitivity responses to 2,4-dinitrofluorobenzene (DNFB) was obviously enhanced in OPN-T mice. In the delayed-type hypersensitivity (DTH) model elicited by DNFB, the number of CD8+ T cells among DNFB-2,4,6-trinitrobenzenesulfonic acid (TNBS)-peritoneal exudate cells was significantly higher in OPN-T than nontransgenic mice, while there was almost no difference in that of CD4+ T cells. Adoptive transfer experiments revealed that the enhanced reactivity is carried by CD4+ and CD8+ T cells, respectively, although the ability of transferring DTH was significantly lower in CD8+ than in CD4+ T cells. The enhancement of CD8+ T cell migration was observed in OPN-T mice. These results suggest that OPN induces a proliferation of effector CD4+ and CD8+ cells in cell-mediated reactions and plays a role in the migration of CD8+ T cells.

Expression of murine N-MYC by insertion of retrovirus sequences in a murine macrophage cell line (RAW264)

RAW264 cells, reported to be originated from Abelson-virus-induced B lymphomas, are widely used as a murine monocyte cell line. We found that RAW264 show enhanced expression of murine N-MYC. Murine cDNA clones associated with N-MYC were separated from (lambda)gt11 cDNA library constructed by using mRNA from the macrophage cell line, RAW264 cells. Sequencing analysis of the longest cDNA clone N-MYCL showed that the length of the coding region was 18 bases shorter than that of the predicted full length N-MYC cDNA, and the 3' untranslated region had the 5' long terminal repeat (LTR) sequence of the Moloney-like proviral sequence, suggesting the expression of N-MYC by insertion of the proviral sequence. This suggests that expression of N-MYC plays a role in the establishment of macrophage cell line RAW264. Integration of LTR and overexpression of the N-MYC gene might have existed in the parental lymphoma cells, playing a role in the development of lymphoma or in the establishment of macrophage cell line.