Junichi Furuta

Somatic RHOA mutation in angioimmunoblastic T cell lymphoma

Angioimmunoblastic T cell lymphoma (AITL) is a distinct subtype of peripheral T cell lymphoma characterized by generalized lymphadenopathy and frequent autoimmune-like manifestations. Although frequent mutations in TET2, IDH2 and DNMT3A, which are common to various hematologic malignancies, have been identified in AITL, the molecular pathogenesis specific to this lymphoma subtype is unknown. Here we report somatic RHOA mutations encoding a p.Gly17Val alteration in 68% of AITL samples. Remarkably, all cases with the mutation encoding p.Gly17Val also had TET2 mutations. The RHOA mutation encoding p.Gly17Val was specifically identified in tumor cells, whereas TET2 mutations were found in both tumor cells and non-tumor hematopoietic cells. RHOA encodes a small GTPase that regulates diverse biological processes. We demonstrated that the Gly17Val RHOA mutant did not bind GTP and also inhibited wild-type RHOA function. Our findings suggest that impaired RHOA function in cooperation with preceding loss of TET2 function contributes to AITL-specific pathogenesis.

Identification of 27 5' CpG islands aberrantly methylated and 13 genes silenced in human pancreatic cancers.

Aberrantly methylated DNA fragments were searched for in human pancreatic cancers, using the genome scanning technique: methylation-sensitive-representational difference analysis (MS-RDA). MS-RDA isolated 111 DNA fragments derived from CpG islands (CGIs), and 35 of them were from CGIs in the 5′ regions of known genes. Methylation-specific PCR (MSP) of the CGIs in seven pancreatic cancer cell lines and two pancreatic ductal epithelial cell lines showed that 27 CGIs in the 5′ regions were aberrantly methylated in at least one of the cancer cell lines. Quantitative reverse-transcription–PCR analysis showed that downstream genes of all the CGIs were either not expressed or only very weakly expressed in cancer cell lines with the aberrant methylation. In the pancreatic ductal epithelial cell lines, 18 genes were expressed at various levels, and nine genes were not expressed at all. Treatment of a cancer cell line with a demethylating agent, 5-aza-2′-deoxycytidine, restored the expression of 13 genes, RASGRF2, ADAM23, NEF3, NKX2-8, HAND1, EGR4, PRG2, FBN2, CDH2, TLL1, NPTX1, NTSR1 and THBD, showing their silencing by methylation of their 5′ CGIs. MSP of 24 primary pancreatic cancers showed that all these genes, except for THBD, were methylated in at least one cancer. Some of those were suggested to be potentially involved in pancreatic cancer development and progression.

Promoter methylation profiling of 30 genes in human malignant melanoma

Aberrant methylation and demethylation of promoter CpG islands lead to silencing of tumor‐suppressor genes and abnormal expression of normally methylated genes, respectively. Here, we analyzed human melanomas for their methylation and demethylation profiles. Methylation status of core regions in promoter CpG islands was examined for 20 (candidate) tumor‐suppressor genes, 4 genes that are not considered as tumor‐suppressors, but are frequently silenced in human cancers, and 6 normally methylated melanoma antigen genes (MAGEs). Analysis of 13 melanoma cell lines and 2 cultured normal human epidermal melanocytes (HEMs) showed that 9 tumor‐suppressor genes and all 4 non‐tumor‐suppressor genes were methylated in at least 1 cell line, but never in HEMs, and that all 6 MAGE genes were demethylated in 3 to 13 cell lines. Interestingly, we detected no methylation of MGMT, PTEN, MTAP and p27, which were previously reported as silenced in melanomas. Furthermore, 3 genes that were frequently methylated in the cell lines and 6 MAGE genes were analyzed in 25 surgical melanoma samples. RARB, RASSF1A and 3‐OST‐2 were methylated in 5 (20%), 9 (36%) and 14 (56%) samples, respectively. MAGE‐A1, A2, A3, B2, C1 and C2 were demethylated in 9 (36%), 22 (88%), 20 (80%), 7 (28%), 21 (84%) and 16 (64%) samples, respectively. At least 1 gene was methylated in 18 (72%) samples and at least 1 was demethylated in 24 (96%) samples. No correlation between frequent methylation and frequent demethylation was observed. These profiles showed that both aberrant methylation and demethylation occur widely in human melanomas.

Silencing of tissue factor pathway inhibitor‐2 gene in malignant melanomas

To identify tumor‐suppressor genes inactivated by aberrant methylation of promoter CpG islands (CGIs) in human malignant melanomas, genes upregulated by treatment of cells with a demethylating agent, 5‐aza‐2′‐deoxycytidine (5‐aza‐dC), were searched for using oligonucleotide microarrays in melanoma cell lines, HMV‐I, MeWo and WM‐115. Seventy‐nine known genes with CGIs were identified as being upregulated (≥16‐fold), and 18 of them had methylation of their putative promoter CGIs in 1 or more of 8 melanoma cell lines. Among the 18 genes, TFPI‐2, which is involved in repression of the invasive potential of malignant melanomas, was further analyzed. Its expression was repressed in a melanoma cell line with its complete methylation, and was restored by 5‐aza‐dC treatment. It was unmethylated in cultured neonatal normal epidermal melanocyte, and was induced by ultraviolet B. In surgical melanoma specimens, TFPI‐2 methylation was detected in 5 of 17 metastatic site specimens (29%), while it was not detected in 20 primary site specimens (0%) (p = 0.009). By immunohistochemistry, the 5 specimens with promoter methylation lacked immunoreactivity for TFPI‐2. The results showed that TFPI‐2 is silenced in human malignant melanomas by methylation of its promoter CGI and suggested that its silencing is involved in melanoma metastasis.

Severe local skin reactions to interferon beta-1b in multiple sclerosis-improvement by deep subcutaneous injection

Severe local skin reactions to subcutaneous injection of interferon beta-1b in multiple sclerosis are rare, and only 12 cases of severe skin reaction due to interferon beta-1b have been reported to date. We report two cases of severe skin reactions in multiple sclerosis patients following the injection of subcutaneous interferon beta-1b. In case 1, after five years of treatment, a painful indurated erythematous lesion appeared at the injection site on the left buttock. On histological analysis, the lesion showed septal and lobular panniculitis with lymphocytic infiltration. In case 2, cutaneous ulceration was surrounded by painful induration, which developed at the injection site on the right thigh after four years of treatment. The lesions resolved rapidly after discontinuation of interferon beta-1b treatment in both cases. Here, we review cases of similar lesions caused by interferon beta-1b reported in the literature, and discuss the characteristics, mechanism, treatment, and prevention of such lesions.

A randomized double-blind trial of intravenous immunoglobulin for bullous pemphigoid.

BACKGROUND Patients with steroid-resistant bullous pemphigoid (BP) require an appropriate treatment option. OBJECTIVE A multicenter, randomized, placebo-controlled, double-blind trial was conducted to investigate the therapeutic effect of high-dose intravenous immunoglobulin (IVIG; 400mg/kg/day for 5days) in BP patients who showed no symptomatic improvement with prednisolone (≥0.4mg/kg/day) administered. METHODS We evaluated the efficacy using the disease activity score on day15 (DAS15) as a primary endpoint, and changes in the DAS over time, the anti-BP180 antibody titer, and safety for a period of 57days as secondary endpoints. RESULTS We enrolled 56 patients in this study. The DAS15 was 12.5 points lower in the IVIG group than in the placebo group (p=0.089). The mean DAS of the IVIG group was constantly lower than that of the placebo group throughout the course of observation, and a post hoc analysis of covariance revealed a significant difference (p=0.041). Furthermore, when analyzed only in severe cases (DAS≥40), the DAS15 differed significantly (p=0.046). The anti-BP180 antibody titers showed no difference between the two groups. CONCLUSION IVIG provides a beneficial therapeutic outcome for patients with BP who are resistant to steroid therapy.

Silencing of the thrombomodulin gene in human malignant melanoma.

The loss of thrombomodulin (TM) expression is associated with tumour growth, infiltration and lymph node metastasis in human tumours. In melanoma cell lines, TM is reported to mediate cell adhesion, and its introduction into TM-negative melanoma cell lines suppresses their growth. In this study, we analysed TM expression in surgical melanoma specimens and the role of its promoter methylation in the loss of its expression. In 15 (75%) of the 20 specimens (five from a primary site and 15 from metastatic sites), melanoma cells lacked TM immunoreactivity. Methylation of the TM promoter region was detected in 10 (67%) of the 15 TM-negative specimens by methylation-specific polymerase chain reaction, whereas methylation was detected in two (40%) of the five TM-positive specimens. In cell lines, complete methylation of the TM promoter CpG island was detected in six (46%) of 13 melanoma cell lines, whereas no methylation was detected in two cultured normal melanocytes. There was a good correlation between the methylated status of the CpG island and the loss of TM messenger RNA (mRNA) expression. Treatment of melanoma cell lines with a demethylating agent, 5-aza-2′-deoxycytidine, induced demethylation of the promoter CpG island and the restoration of mRNA and protein expression. These findings suggest that most human melanomas lack TM expression, and that methylation of the promoter CpG island is one of the mechanisms responsible.

Improvement of the sentinel lymph node detection rate of cervical sentinel lymph node biopsy using real‐time fluorescence navigation with indocyanine green in head and neck skin cancer

The standard technique using lymphoscintigraphy, blue dye and a gamma probe has established a reliable method for sentinel node biopsy for skin cancer. However, the detection rate of cervical sentinel lymph nodes (SLN) is generally lower than that of inguinal or axillary SLN because of the complexity of lymphatic drainage in the head and neck region and the “shine‐through” phenomenon. Recently, indocyanine green fluorescence imaging has been reported as a new method to detect SLN. We hypothesized that fluorescence navigation with indocyanine green in combination with the standard technique would improve the detection rate of cervical sentinel nodes. We performed cervical sentinel node biopsies using the standard technique in 20 basins of 18 patients (group A) and using fluorescence navigation in combination with the standard technique in 12 basins of 16 patients (group B). The mean number of sentinel nodes was two per basin (range, 1–4) in group A and three per basin (range, 1–5) in group B. The detection rate of sentinel nodes was 83% (29/35) in group A and 95% (36/38) in group B. The false‐negative rate was 6% (1/18 patients) in group A and 0% in group B. Fluorescence navigation with indocyanine green may improve the cervical sentinel node detection rate. However, greater collection of data regarding the usefulness of cervical sentinel node biopsy using indocyanine green is necessary.

Hereditary complement (C9) deficiency associated with dermatomyositis

A 28‐year‐old Japanese woman with hereditary complement (C9) deficiency and dermatomyositis is reported. She had a 3‐year history of facial erythema and a 1‐month history of progressive muscle weakness. Clinical and laboratory findings were suggestive of dermatomyositis; muscle biopsy confirmed an inflammatory myopathy. An unexpected finding, however, was the low titre of serum haemolytic complement (CH50). Treatment with prednisolone resulted in marked clinical improvement but did not affect the CH50 titre. Further investigation revealed a selective and total absence of the ninth complement component (C9), with direct DNA sequence analysis revealing a non‐sense mutation at Arg95 of the C9 gene. This case demonstrates that the muscle lesions of dermatomyositis can occur in the presence of a complement defect that would prevent the formation of the C5b‐9 membrane attack complex.

Usefulness of sentinel lymph node biopsy for extramammary Paget disease.

In the present study, we sequenced the RPL21 gene in a Chinese family and could not find any variant. However, we identified a recurrent mutation, c.26T>G (p.Leu9Arg), in the APCDD1 gene. The mutation p.Leu9Arg is located within the cleavage site of the APCDD1 protein which has been shown to be highly conserved during evolution among dog, horse, mouse and bat, and may be critical for the function of the protein.