Hiromitsu Hoshino

Osaka City University, Ōsaka, Ōsaka, Japan

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Publications (8)22.27 Total impact

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    ABSTRACT: Cancer is initiated by the transformation of stem cells or progenitor cells via a dedifferentiation process that leads to cancer stem cells; however, the process involves the activation of growth-promoting oncogenes and the inactivation of growth-constraining tumor suppressor genes. The introduction of defined factors, such as those encoded by c-Myc, Sox2, Oct3/4 and Klf4, in normal somatic cells results in their dedifferentiation into induced pluripotent stem (iPS) cells. We previously reported that these defined factors induced the development of induced multipotent cancer (iPC) cells from gastrointestinal cancer cells by reducing tumor aggressiveness. Previous studies indicated that although reprogramming may be facilitated by p53 inhibition, gain-of-function oncogenic mutations in p53 and oncogenic mutations in Kras-stimulated tumorigenic activity, and their roles in vivo are imperfectly understood. Hence, in the present study, the effect of direct injection of a Sendai virus (SeV) vector encoding four defined factors in vivo was studied using various backgrounds of transgenic and knockout mice, and was compared with that of direct injection of microRNAs (miRNAs) diluted with cationic lipid. The in vivo imaging data revealed transformation hot spots for p53 deficiency or conditional activation of mutant Kras, and the sizes were concordant with those in immuno-deficient NOD/SCID and uPA-NOG mice, as well as larger compared with those in the control mice. Overall, the present data on in vivo reprogramming indicated that Kras activation may facilitate the effect of cellular reprogramming in normal liver cells, and the effect of Kras activation is more apparent than that of tumor suppressor p53 deficiency. The results also revealed that immunodeficiency may increase the effect of reprogramming, presumably by blocking the immunosurveillance of transformed cells. These findings provide a rationale for further studies to develop a therapeutic approach involving direct in vivo reprogramming.
    Oncology letters 08/2013; 6(2):323-328. · 0.24 Impact Factor
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    ABSTRACT: Induced pluripotent stem (iPS)-like cancer cells (iPC) by the introduction of defined transcription factors reduce the prevalence of the malignant phenotype of digestive system cancer cells, but the induction efficiency is low. The role of hypoxia and TP53 deficiency in iPC cell generation remain unclear. Cellular reprogramming was performed by retroviral infection with OCT3/4, SOX2, KLF4 and c-MYC of wild-type HCT116 colorectal cancer cells and mutant TP53-deficient HCT116 cells. Cells were cultured in normoxia (21% O2) or hypoxia (5% O2) for 30 days after transduction, and the response to hypoxia and comparison of cellular proliferation, invasion and tumourigenesis before and after iPC cell generation were studied. iPC cell generation from wild-type HCT116 cells in hypoxia was approximately 4-times greater than in normoxia (p<0.05), and TP53 deficiency increased conversion efficiency significantly in normoxia (p<0.05). Significant involvement of hypoxia-inducible factors was observed in an immature carbohydrate epitope, Tra-1-60+, colony formation. Generated iPC cells exhibited multi-differentiation potential. Although the iPC cells in hypoxia exhibited reduced proliferation, invasiveness and tumourigenicity, TP53 deficiency in iPC cells resulted in higher tumourigenicity than in wild-type cells. Both hypoxia and TP53 deficiency increase iPC cell generation. TP53 deficiency can also result in deleterious mutations, whereas hypoxia may impact molecular targets of epigenome normalisation.
    International Journal of Oncology 01/2012; 40(5):1423-30. · 2.66 Impact Factor
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    ABSTRACT: Histopathologically confirmed lymph node metastasis is a prognostic factor in the surgical treatment of biliary tract cancer, however, preoperative diagnosis is still difficult even with computed tomography. FDG-PET has been used for the diagnosis of cancer and metastatic lesions. Herein, we retrospectively evaluated the utility of FDG-PET for detection of lymph node metastasis in biliary tract cancer. We measured SUV(max) at each 190 surgically dissected lymph node area in 36 patients, and compared the values with histopathological diagnosis. The cutoff values for SUV(max) were defined from the ROC curve and the mean plus two standard deviations then used for detection of metastatic lymph node and prognostic value, compared with CT diagnosis. The sensitivity, specificity, and positive predictive value of FDG-PET were better than CT diagnosis (86%, 74%, 43% for SUV(max) ≥ 2.0, and 37%, 97%, 72% for SUV(max) ≥ 2.8, respectively). There was no relationship between SUV(max) and CT-determined lymph node dimensions. The presence of SUV(max) ≥ 2.8 lymph nodes was an independent determinant of prognosis after surgical treatment. The detection of metastatic lymph nodes by FDG-PET is limited, but better than CT. SUV(max) for lymph nodes seems useful for clinical decision-making regarding treatment strategy including surgery.
    Journal of Surgical Oncology 03/2011; 103(3):223-9. · 2.64 Impact Factor
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    ABSTRACT: The management of branch duct-type intraductal papillary mucinous neoplasms (IPMNs) remains controversial. This study aimed to elucidate the preoperative clinical factors that identify high-risk malignant transformation in branch duct-type IPMN. We retrospectively evaluated 38 patients diagnosed with branch duct-type IPMN who underwent pancreatectomy, identifying different preoperative factors between adenoma (intraductal papillary mucinous adenoma [IPMA]) and carcinoma (intraductal papillary mucinous carcinoma [IPMC]). Twelve patients were diagnosed with IPMC. The mean tumor size was 31.9 ± 11.8 mm for IPMA and 35.7 ± 17.1 mm for IPMC (P = .467). No significant differences were found between IPMA and IPMC patients with regard to age, sex, symptoms, and tumor number. The mean diameter of the main pancreatic duct was significantly larger in IPMCs (8.3 ± 5.9 mm) compared with IPMAs (4.7 ± 2.3 mm; P = .011). The mural nodule was a good predictor of malignancy (P = .0002) and was identified as the only independent and significant marker of IPMC in multivariate analysis. The presence of mural nodules is a potentially suitable marker for differentiating IPMC from IPMA, and is important for making decisions about surgical interventions.
    American journal of surgery 03/2011; 202(2):214-9. · 2.36 Impact Factor
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    ABSTRACT: We recently reported that gastrointestinal (GI) cancer cells can be reprogrammed to a pluripotent state by the ectopic expression of defined embryonic stem (ES)-like transcriptional factors. The induced pluripotent cancer (iPC) cells from GI cancer were sensitized to chemotherapeutic agents and differentiation-inducing treatment during a short-term culture, although a phenotype induced by long-term culture needs to be studied. A long-term cultured (Lc)-iPC cells were produced in GI cancer cell lines by virus-mediated introduction of four ES-like genes-c-MYC, SOX2, OCT3/4, and KLF4-followed by a culture more than three months after iPC cells induction. An acquired state was studied by expression of immature-related surface antigens, Tra-1-60, Tra-1-81, Tra-2-49, and Ssea-4; and epigenetic trimethyl modification at lysine 4 of histone H3. Sensitivity to chemotherapeutic agents and tumorigenicity were studied in Lc-iPC cells. Whereas the introduction of defined factors of iPC cells once induced an immature state and sensitized cells to therapeutic reagents, the endogenous expression of the ES-like genes except for activated endogenous c-MYC was down-regulated in a long-term culture, suggesting a high magnitude of the reprogramming induction by defined factors and the requirement of therapeutic maintenance in Lc-iPC cells from cholangiocellular carcinoma HuCC-T1 cells, which harbor TP53(R175H) and KRAS(G12D). The Lc-iPC cells showed resistance to 5-fluorouracil in culture, and high tumorigenic ability with activated endogenous c-MYC in immunodeficient mice. The Lc-iPC cells from HuCC-T1 might be prone to an undesirable therapeutic response because of an association with the activated endogenous c-MYC. To consider the possible therapeutic approach in GI cancer, it would be necessary to develop a predictive method for evaluating the improper reprogramming-associated aggressive phenotype of iPC cells.
    Biochemical and Biophysical Research Communications 04/2010; 395(2):258-63. · 2.28 Impact Factor
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    ABSTRACT: Although cancer is a disease with genetic and epigenetic origins, the possible effects of reprogramming by defined factors remain to be fully understood. We studied the effects of the induction or inhibition of cancer-related genes and immature status-related genes whose alterations have been reported in gastrointestinal cancer cells. Retroviral-mediated introduction of induced pluripotent stem (iPS) cell genes was necessary for inducing the expression of immature status-related proteins, including Nanog, Ssea4, Tra-1-60, and Tra-1-80 in esophageal, stomach, colorectal, liver, pancreatic, and cholangiocellular cancer cells. Induced cells, but not parental cells, possessed the potential to express morphological patterns of ectoderm, mesoderm, and endoderm, which was supported by epigenetic studies, indicating methylation of DNA strands and the histone H3 protein at lysine 4 in promoter regions of pluripotency-associated genes such as NANOG. In in vitro analysis induced cells showed slow proliferation and were sensitized to differentiation-inducing treatment, and in vivo tumorigenesis was reduced in NOD/SCID mice. This study demonstrated that pluripotency was manifested in induced cells, and that the induced pluripotent cancer (iPC) cells were distinct from natural cancer cells with regard to their sensitivity to differentiation-inducing treatment. Retroviral-mediated introduction of iPC cells confers higher sensitivity to chemotherapeutic agents and differentiation-inducing treatment.
    Proceedings of the National Academy of Sciences 12/2009; 107(1):40-5. · 9.81 Impact Factor
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    ABSTRACT: Gemcitabine monotherapy is accepted as a standard first-line treatment for locally advanced unresectable or metastatic pancreatic cancer. On another front, S-1 and gemcitabine combination chemotherapy is challenging but promising. We report a long-term survival case of pancreatic cancer with hepatic metastasis after surgical resection treated by S-1 and gemcitabine combination chemotherapy. A 59-year-old woman was diagnosed as locoregionally advanced pancreas head cancer without metastatic disease. Pancreatoduodenectomy with regional lymph node dissection was performed after preoperative chemoradiotherapy. Pathological examination revealed a poorly differentiated adenocarcinoma. A solitary hepatic metastasis was detected by CT imaging one year after the surgery. The patient received 35 courses of S-1 and gemcitabine combination therapy. The metastatic tumor was disappeared, and serum CEA decreased to a normal level. S-1 and gemcitabine combination therapy is not only effective but also well tolerated and safe. This combination therapy should be considered one of selective choices for advanced or metastatic pancreatic cancer.
    Gan to kagaku ryoho. Cancer & chemotherapy 11/2009; 36(12):2419-21.
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    ABSTRACT: Previous reports have demonstrated that SNAI1 plays a role in epithelial-mesenchymal transition (EMT) through the suppression of CDH1. Its role in the pathology and regulation of EMT expression to chemoresistance in colorectal cancer (CRC) has not yet been fully elucidated. Immunohistochemistry was performed to evaluate the expression of Snai1 protein in 30 primary CRC samples. The biological significance of Snai1 expression was studied by induction of the wild-type (WT) and mutant SNAI1 gene in CRC SW480 cells. Examination of 20 surgical specimens of CRC indicated that Snai1 protein expression was localized outer regions of invasive tumors. Introduction of phosphorylation-defective active EMT forms, SNAI1-6SA and SNAI1-8SA, caused downregulation of CDH1 and upregulation of VIM compared with SNAI1-WT and the negative control (NC). Chemoresistance to 5-fluorouracil (IC50) was higher in SNAI1-6SA and SNAI1-8SA transfectants compared with SNAI1-WT and NC. All the above results were significantly different. The present study demonstrated that Snai1 plays a role in CRC invasion through phosphorylation, suggesting a plausible mechanism for overcoming chemoresistance that will lead to the development of effective treatments for CRC.
    Biochemical and Biophysical Research Communications 10/2009; 390(3):1061-5. · 2.28 Impact Factor