Tatsuki R. Kataoka

Annexin VII as a novel marker for invasive phenotype of malignant melanoma.

Both F10 and BL6 sublines of B16 mouse melanoma cells are metastatic after intravenous injection, but only BL6 cells are metastatic after subcutaneous injection. While examining the genetic difference between the two sublines, we found a marked reduction of annexin VII expression in BL6 cells. In addition, fusion cell clones of both sublines, were as poorly metastatic as F10 cells after subcutaneous injection, and contained the annexin VII message as abundantly as F10 cells. Hence, we examined whether the annexin VII expression was correlated with the less malignant phenotype of clinical cases by immunohistochemistry. Immunoreactivities to anti‐annexin VII antibody in melanoma cells were evaluated quantitatively by using skin mast cells as an internal positive control. Eighteen patients with malignant melanoma were divided into two groups: lymph node metastasis‐negative and positive groups. The ratio of numbers of patients positive versus negative to the antibody was significantly larger in the former than in the latter group. These results not only indicated that annexin VII serves as a marker for less invasive phenotype of malignant melanoma, but also suggested a possible role of annexin VII in tumor suppression.

Concomitant hepatocellular carcinoma and non-Hodgkin's lymphoma in a patient with nodular regenerative hyperplasia

Hepatocellular carcinoma (HCC) is the most common primary cancer in the liver. Liver invasion of non‐Hodgkins lymphoma (NHL) is also often observed. But simultaneous existence of HCC and NHL in a liver is extremely rare. Such patients reported previously had cirrhotic livers. Herein is reported a patient who simultaneously had HCC and NHL in a liver without cirrhosis, but with nodular regenerative hyperplasia (NRH). NHL was of the diffuse large B‐cell type. Lymphoma cells invaded the portal vein, and formed thrombi. These thrombi would contribute to the development of NRH by decreasing portal vein blood flow. HCC was of the well‐differentiated type and there was a 2 cm‐sized nodule at the lateral segment. There is the possibility that NRH was associated with the HCC because NRH is reported as a premalignant lesion. HCC and NHL were colocalized in the liver without hepatic virus infection or cirrhosis, although common cause(s) of development of these malignancies remain unclear in the present case.

Reduced expression of IL-12 receptor β2 and IL-18 receptor α genes in natural killer cells and macrophages derived from B6-mi/mi mice

The mi transcriptional factor (MITF) is a basic helix–loop–helix leucine zipper-type transcriptional factor. The mi mutant allele encodes an abnormal MITF, in which one out of four consecutive arginines is deleted in the basic domain. The VGA-9-tg (tg) allele is another mutant allele and considered to be a null mutant allele. C57BL/6 (B6)-mi/mi mice showed abnormal phenotypes of natural killer (NK) cells and macrophages, whereas B6-tg/tg mice did not. The expression levels of the genes for the interleukin-12 receptor (IL-12R) β2 and IL-18Rα were reduced in both the NK cells and macrophages of B6-mi/mi mice, while the expression levels of the corresponding genes in B6-tg/tg mice were unaffected. The B6-mi/mi NK cells and B6-mi/mi macrophages showed impaired responses to stimulation with IL-12, IL-18, and IL-12 plus IL-18 stimulation. The abnormal NK cell and macrophage of B6-mi/mi mice appear to be due to decreased expression of the IL-12Rβ2 and IL-18Rα genes.

A new member of the GTPase superfamily that is upregulated in highly metastatic cells

Two sublines of B16 melanoma cells, F10 and BL6, are metastatic after intravenous injection, but only BL6 cells are metastatic after subcutaneous injection. We found a new member of the GTPase superfamily, namely TIB929, which displayed an induction of expression in BL6 cells. It conserved three consensus sequences for GTP-binding site motifs and showed a significant homology to the yeast Gtr2 gene throughout the coding sequence. TIB929 was expressed ubiquitously in human tumor cells, with a marked expression in highly metastatic cells. TIB929 was mapped on mouse chromosome 4D, syntenic to human chromosome 1p. The results suggested an involvement of TIB929 in malignant progression.

Dual abnormal effects of mutant MITF encoded by Miwh allele on mouse mast cells: decreased but recognizable transactivation and inhibition of transactivation

MITF is a basic helix-loop-helix leucine zipper-type transcription factor and is important for development of mast cells. MITF encoded by Mi(wh) allele (Mi(wh)-MITF) was mutated at a single amino acid of basic domain, and possessed a deficient but apparent DNA-binding ability. Here, we characterized the unique effects of Mi(wh)-MITF on the expression of mast cell-related genes. The expression level of mouse mast cell protease (mMCP)-4, -5, and -6 genes in Mi(wh)/Mi(wh) cultured mast cells (CMCs) was intermediate between levels of normal (+/+) CMCs and tg/tg CMCs, which did not express any MITFs. Mi(wh)-MITF appeared to show the positive transactivation effect through the remaining DNA-binding ability. On the other hand, the expression level of tryptophan hydroxylase gene was lower in Mi(wh)/Mi(wh) CMCs than in tg/tg CMCs, suggesting the inhibitory effect of Mi(wh)-MITF on the transactivation. Mi(wh)-MITF possessed dual abnormal effects on transactivation of mast cell-related genes.

Stat4 suppresses the proliferation of connective tissue-type mast cells

Mast cells are the progeny of hematopoietic stem cells, and murine mast cells are usually divided into two distinct populations, mucosal mast cells (MMCs) and connective tissue-type mast cells (CTMCs). We previously reported that CTMCs expressed signal transducer and activator of transcription (Stat) 4, but MMCs did not. Stat4 is also expressed in T cells and plays important roles in their homeostasis. In the present study, we show that Stat4 is involved in the homeostasis of CTMCs. The number of skin CTMCs increased in Stat4-deficient Balb/c mice, but that of gastric MMCs did not, when compared to those in control Balb/c+/+ mice. The comparison between cultured Stat4-deficient CTMCs and cultured Balb/c+/+ CTMCs revealed that cell cycle progression and cyclin D3 expression in the cultured Stat4-deficient CTMCs were enhanced in a Stat3 activation-dependent manner. This phenotype was explained by upregulation of KitL-induced interleukin (IL)-6 acting in an autocrine manner in cultured Stat4-deficient CTMCs. These results show that Stat4 suppresses the proliferation of CTMCs by controlling IL-6 via an autocrine mechanism.

Nuclear Expression of STAT5 in Intraductal Papillary Mucinous Neoplasms of the Pancreas

Intraductal papillary mucinous neoplasms (IPMNs) are noninvasive lesions of the pancreas and classified as intraductal papillary mucinous adenomas (IPMAs), borderline IPMNs, and intraductal papillary mucinous carcinomas (IPMCs). Expression patterns of the specific genes alter during IPMN progression. Based on the evidence that signal transducers and activators of transcription (STAT) 5 play important roles in tumor development, we tested STAT5 expression in IPMAs, borderline IPMNs, and IPMCs by immunohistochemical method. STAT5 frequently expressed in the nuclei of tumor cells of borderline IPMNs or IPMCs but was not observed in those of IPMAs. Nuclear expression of STAT5 protein correlated to the Ki-67 labeling index of the examined IPMNs. STAT5 protein could contribute to the progression and proliferation of IPMNs.

Toriello–Carey syndrome associated with respiratory failure and non‐mechanical ileus

Toriello–Carey syndrome comprises agenesis of the corpus callosum, telecanthus, small palpebral fissures, Pierre Robin sequence, abnormal ears, and cardiac defects. We report a boy who has some additional findings, including a severe respiratory failure and intestinal dysmotility. The boy died of these two disorders at age 13 months. Histological examination revealed pulmonary immaturity and a defect of smooth muscle cells in the longitudinal muscle coat of the intestinal musculature, both of which might explain some aspects of the pathophysiology of the patient.

Expression of p21Cip1/Waf1 and p27Kip1 in small cell neuroendocrine carcinoma of the uterine cervix.

Small-cell neuroendocrine carcinoma of the uterine cervix (SCCC), a rare but malignant cervical neoplasm, has a highly aggressive phenotype that requires more intensive treatment than other cervical tumors. Immunohistochemical methods were used to compare the expression of p21Cip1/Waf1 and p27Kip1 in SCCC and squamous cell carcinoma, the most common type of cervical cancer. In SCCC, p21 expression was significantly reduced compared with squamous cell carcinoma, whereas expression of p27 was similar in both carcinomas. Reduced expression of p21 could be a helpful diagnostic marker and may contribute to the invasive phenotype of SCCC.