Biomedical subjects

Takashi Shimokawa

Publications and source records attributed to Takashi Shimokawa.

At least 19 recordsLinked to original sources

PubMed2006

Inhibition of GLI1 gene activation by Patched1.

Patched1 (PTCH1) is a human tumour suppressor that acts as an HH (Hedgehog) receptor protein and is important for embryonic patterning. PTCH1 mediates its effects through SMO (Smoothened) and represses the expression of HH target genes such as the transcription factor GLI1 (glioma 1) as well as PTCH1. Up-regulation of these genes has been observed in several cancer forms, including basal cell carcinoma, digestive track tumours and small cell lung cancer. The fact that PTCH1 down-regulates its own expression via 'negative feedback' is an important feature in HH signalling, as it keeps the balance between HH and PTCH1 activities that are essential for normal development. In the present study, we provide evidence that a novel mechanism allowing PTCH1 to maintain this balance may also exist. We show that gene activation by GLI1, the transcriptional effector of the pathway, can be down-regulated by PTCH1 without involvement of the canonical cascade of HH signalling events. Specifically, the SMO antagonist cyclopamine has no appreciable effects in blocking this PTCH1-mediated inhibition. Moreover, the negative GLI1 regulator SUFU (Suppressor of Fused) was also found to be dispensable. Additionally, deletion mapping of PTCH1 has revealed that the domains encompassed by amino acids 180-786 and 1058-1210 are of highest significance in inhibiting GLI1 gene activation. This contrasts with the importance of the PTCH1 C-terminal domain for HH signalling.

Animals↗

PubMed2006

PTCH mutations: distribution and analyses.

Mutations in the PTCH (PTCH1) gene are the underlying cause of nevoid basal cell carcinoma syndrome (NBCCS), and are also found in many different sporadic tumors in which PTCH is thought to act as a tumor suppressor gene. To investigate the distribution pattern of these mutations in tumors and NBCCS, we analyzed 284 mutations and 48 SNPs located in the PTCH gene that were compiled from our PTCH mutation database. We found that the PTCH mutations were mainly clustered into the predicted two large extracellular loops and the large intracellular loop. The SNPs appeared to be clustered around the sterol sensing domain and the second half of the protein. The NBCCS cases and each class of tumor analyzed revealed a different distribution of the mutations in the various PTCH domains. Moreover, the types of mutations were also unique for the different groups. Finally, the PTCH gene harbors mutational hot spot residues and regions, including a slippage-sensitive sequence in the N-terminus.

Basal Cell Nevus Syndrome↗

PubMed2006

Identification of TOMM34, which shows elevated expression in the majority of human colon cancers, as a novel drug target.

In an attempt to isolate potential molecular targets for diagnosis, treatment and/or prevention of colorectal cancer (CRC), we have been analyzing expression profiles of clinical samples from CRC patients using genome-wide cDNA microarray. Among the genes up-regulated frequently in colorectal tumors, we here focused on TOMM34 (34 kDa-translocase of the outer mitochondrial membrane). Immunohistochemical staining revealed significant accumulation of TOMM34 protein in CRC tissues compared with their corresponding non-cancerous mucosae. Transfection of colon cancer HCT116 cells with short-interfering RNA (siRNA) specific to TOMM34 effectively suppressed its expression and drastically inhibited cell growth. These findings suggest that TOMM34 is involved in the growth of cancer cells, and may contribute to the development of novel anticancer drugs and/or diagnosis for CRC.

Animals↗

PubMed2005

Surgical anatomy of the innervation of the major duodenal papilla in human and Suncus murinus, from the perspective of preserving innervation in organ-saving procedures.

OBJECTIVES: Few studies have focused on the detailed surgical anatomy of the innervation of the major duodenal papillary region, especially in relation to duodenum-preserving pancreatic head resection (DPPHR) and its modified procedures, which is crucial to preserving the innervation of the papillary region. The aim of this study is to clarify the neural distribution of the major duodenal papilla in humans. METHODS: The pancreas, duodenum, and surrounding structures were dissected in 10 cadavers and immersed in a 0.001% solution of alizarin red S in ethanol to stain the peripheral nerves. The details of the innervation in the above areas were confirmed using a binocular microscope. Similarly, the distribution in 10 Suncus murinus was examined by whole mount immunohistochemistry method with antineurofilament protein antibody. RESULTS: The innervation of the papillary region in humans involved 2 systems. One arose from the celiac plexus, which through the anterior hepatic plexus running along the arcades of the superior pancreaticoduodenal arteries and through the posterior hepatic plexus running along or accompanying the common bile duct (CBD) or Wirsung's duct, innervated the papillary region. The other arose from the superior mesenteric plexus wound around the arcades of the inferior pancreaticoduodenal arteries innervating the papillary region. The results in S. murinus supported those in humans. CONCLUSIONS: We emphasize the importance of the nervus-preserving of the major duodenal papilla and CBD by a suitable pancreatic head remnant, preserving the pancreaticoduodenal arterial arcades and avoiding kocherization of the CBD in DPPHR and its modified procedures.

Aged↗

PubMed2005

Nerve supply to the soft palate muscles with special reference to the distribution of the lesser palatine nerve.

OBJECTIVE: Descriptions of the innervation of the soft palate muscles in previous studies have varied according to the author. In the present study, distribution of the lesser palatine nerve, through which motor fibers of the facial nerve are considered to reach soft palate muscles, and that of the pharyngeal plexus in the soft palate were investigated in order to reexamine the innervation of the soft palate muscles according to anatomical evidence. RESULTS: Observations suggested that the levator veli palatini and palatopharyngeus were doubly innervated by branches of the lesser palatine nerve and pharyngeal plexus, and that the musculus uvulae was innervated by only the lesser palatine nerve. CONCLUSION: The soft palate is considered to be located in the border region between the areas of distribution of the lesser palatine nerve and pharyngeal plexus. This may be why controversies exist in previous studies about the innervation of the soft palate muscles.

Cadaver↗

PubMed2004

A novel first exon of the Patched1 gene is upregulated by Hedgehog signaling resulting in a protein with pathway inhibitory functions.

Patched homolog 1 (PTCH1) is a key component of the Hedgehog (HH) signaling pathway with three alternative first exons, but only exon 1B transcription depending on HH activation. Here, we show that in both human and mouse a novel PTCH1 first exon (1C) is expressed. Exon 1C transcription is upregulated by HH signaling, but the resulting PTCH1-1C protein has a lower capacity for pathway inhibition than PTCH1-1B.

Alternative Splicing↗

PubMed2004

Penetration of muscles by branches of the mandibular nerve: a possible cause of neuropathy.

We carried out detailed dissections of the branches of the mandibular nerve and muscles innervated by these branches to investigate their positional relationships. We made the following observations: 1) small branch of the auriculotemporal nerve penetrated the lateral pterygoid muscle; 2) the entire lingual nerve penetrated the medial pterygoid muscle; and 3) branch of the mylohyoid nerve penetrated the mylohyoid muscle and communicated with the submandibular ganglion. No detailed descriptions of these nerve branches have been reported previously. The existence of these nerve branches that penetrate muscles might result in the neuralgic pain in the trigeminal region when such pain is of unknown origin.

Cadaver↗

PubMed2004

Contributions of the hypoglossal nerve to the innervations of the recti capiti lateralis and anterior.

We dissected five Japanese cadavers (three males, two females) to investigate the innervations of the anterior vertebral muscles. According to our observations, it could be considered that the hypoglossal nerve would participates in the innervations of the recti capiti lateralis and anterior. In addition, we observed the small muscle bundle spanning between the recti capiti lateralis and anterior, which was not reported in previous studies as far as we know. This bundle received a branch of the hypoglossal nerve or the first cervical nerve. Based on the morphology and the innervation pattern, this bundle was considered to have close relationships with the recti capiti lateralis and anterior, especially with the former muscle.

Cadaver↗

PubMed2004

Cellular localization of endocrine cells in the adult pancreas of the house musk shrew, Suncus murinus: a comparative immunocytochemical study.

The right and left lobes of the pancreas in the house musk shrew, Suncus murinus, were found to be completely separated. A morphologic study of the pancreas in S. murinus in terms of the blood supplies and innervation of the right and left lobes was performed in our previous study. It revealed clearly different blood supply and innervation patterns in the right and left lobes, suggesting that the right lobe of the pancreas corresponded to the ventral pancreas, and the left lobe related to the dorsal pancreas. To test this perspective from the histology, in this study, we investigated the immunolocalization of the cells of Langerhans islets in the pancreas of the animal. The distribution of insulin-, glucagon-, somatostatin-, and pancreatic polypeptide (PP)-secreting cells of the right and left lobes of the pancreas was examined in 10 animals. The glucagon-immunoreactive cells were distributed in both the right and left lobes. The PP-immunoreactive cells were extremely abundant in the right lobe and distributed throughout almost all the islets of Langerhans in the right lobe. By contrast, in the left lobe, immunoreactive PP cells were absent in the islets of Langerhans, and only very few immunoreactive PP cells were scattered in the exocrine parenchyma in part of the specimens. Therefore, these findings support our previous studies, and showed that the right and left lobes of the S. murinus pancreas could be related to an embryological origin from the ventral and dorsal pancreatic primordium, respectively, and that the S. murinus pancreas is suitable as a new experimental model to study the development of the human pancreas.

Animals↗

PubMed2004

Genes associated with liver metastasis of colon cancer, identified by genome-wide cDNA microarray.

To uncover mechanisms underlying progression of colorectal carcinogenesis and to identify genes associated with liver metastasis, we analyzed expression profiles of 14 primary colorectal cancers (CRCs) with liver metastases, and compared them with profiles of 11 non-metastatic carcinomas and those of 9 adenomas of the colon. A hierarchical cluster analysis using data from a cDNA microarray containing 23,040 genes indicated that the cancers with metastasis had different expression profiles from those without metastasis, although a number of genes were commonly up-regulated in primary cancers of both categories. We documented 54 genes that were frequently up-regulated and 375 that were frequently down-regulated in primary tumors with metastases to liver, but not in tumors without metastasis. Subsequent quantitative PCR experiments confirmed that PRDX4, CKS2, MAGED2, and an EST (GenBank accession number BF696304) were expressed at significantly higher levels in tumors with metastasis. These data should contribute to a better understanding of the progression of colorectal tumors, and facilitate prediction of their metastatic potential.

Cell Line, Tumor↗

PubMed2004

A novel oncoprotein RNF43 functions in an autocrine manner in colorectal cancer.

We previously analyzed expression profiles of 20 colorectal tumors by means of genome-wide cDNA microarray. Among the genes that were commonly up-regulated in the CRCs, we further characterized biological importance of a novel human gene termed RNF43 (RING finger protein 43) in colorectal carcinogenesis. Multiple-tissue northern blot analysis revealed undetectable expression of RNF43 in normal adult tissues examined and low levels of expression in fetal kidney and lung. Its exogenous expression conferred a growth-promoting effect in COS7 and NIH3T3 cells, and suppression of its expression by specific short interfering RNAs retarded the growth of colon cancer cells. Interestingly, RNF43 protein was shown to be a secreted protein, and addition of the conditioned media of the RNF43-transfected cells into culture media of NIH3T3 cells revealed a significant enhancement of cell growth. These data suggest that RNF43 may exert its growth promoting effect in an antocrine manner, and that it may be a novel diagnostic marker for colorectal cancer.

Blotting, Northern↗

PubMed2003

Involvement of the FGF18 gene in colorectal carcinogenesis, as a novel downstream target of the beta-catenin/T-cell factor complex.

To search for potential molecular targets for development of novel anticancer drugs, we have been analyzing expression profiles of clinical samples from cancer patients, using a genome-wide cDNA microarray. In experiments with colon cancer cells, the gene encoding fibroblast growth factor 18 (FGF18) was among those that showed elevated expression. The promoter region of this gene was found to contain putative Tcf4-binding motifs; moreover a reporter-gene assay using luciferase activity as a marker and an electromobility shift assay indicated that FGF18 is a downstream transcription target in the beta-catenin/Tcf4 pathway. We showed that exogenous FGF18 promoted growth of NIH3T3 cells in an autocrine manner and that transfection of FGF18 short interfering RNAs suppressed growth of colon cancer cells in culture. Our results indicate that FGF18 is activated in colon cancers as a direct downstream target of the Wnt signaling pathway and that it might represent a marker for early diagnosis and a molecular target for treatment of this life-threatening tumor.

Adenocarcinoma↗

PubMed2003

Anatomical study of the pancreas in the house musk shrew (Suncus murinus), with special reference to the blood supply and innervation.

To examine the macroscopic structure, blood supply, and innervation of the pancreas in the house musk shrew (Suncus murinus), we performed gross anatomical dissection and whole-mount immunostaining of the autonomic nerve of Suncus pancreases based on neurofilament protein (NFP) immunoreactivity. The adult Suncus pancreas is clearly separated into right and left lobes that are not fused. The right lobe of the Suncus pancreas is located in the dorsum of the duodenum and to the right of the common bile duct independently. The right lobe is supplied by branches of the superior mesenteric artery, and is innervated by branches that originate from the superior mesenteric plexus and run along the arterial branches of the superior mesenteric artery. The left lobe occupies 9/10 of the entire pancreas and is located to the left of the common bile duct. It is supplied mainly by branches of the splenic and common hepatic arteries, and is innervated by branches that originate from the celiac plexus and run along the splenic and common hepatic arteries. According to previous studies on the blood supply and innervation of the human pancreas, the right and left lobes of the Suncus pancreas correspond to the pancreatic parts derived from the ventral and dorsal pancreatic buds. The current results suggest that the Suncus pancreas is a suitable experimental model for studying the development of the human pancreas.

Animals↗

PubMed2003

Innervation of the pancreas from the perspective of perineural invasion of pancreatic cancer.

INTRODUCTION: Pancreatic cancer invasion via neural routes (perineural invasion) has been studied extensively, but detailed research on the morphology of innervation of the pancreas related to perineural invasion is scarce. AIMS: To clarify the morphology of neural distribution in the human pancreas. METHODOLOGY: The pancreas and surrounding structures were dissected in 9 cadavers, the specimens were immersed in a 0.001% solution of alizarin red S in ethanol to stain the peripheral nerves, and the detailed distribution was studied to confirm the extrapancreatic and intrapancreatic plexus using a binocular microscope. RESULTS: The innervation of the uncinate process of the pancreas originated from the superior mesenteric plexus (SMPlx) along the inferior pancreaticoduodenal artery (IPDA), but did not form a wide offshoot of nerve bundles as reported. Concerning the innervation of the body and tail, it was found that the nerve fibers entered the pancreas immediately after leaving the celiac plexus, and were distributed around the pancreatic duct in a twig-like manner. CONCLUSION: It was emphasized that the nerve originating from SMPlx to the uncinate process chiefly ran along the IPDA and it was necessary to focus one's attention not only on the extrapancreatic perineural invasion but also on the intrapancreatic perineural invasion in carcinoma of the body and tail of the pancreas.

Aged↗

PubMed2002

Isolation of a novel human gene, APCDD1, as a direct target of the beta-Catenin/T-cell factor 4 complex with probable involvement in colorectal carcinogenesis.

To clarify the molecular mechanisms of human carcinogenesis associated with abnormal beta-catenin/T-cell factor (Tcf) signaling, we have been using cDNA microarrays to search for genes whose expression is significantly altered after introduction of wild-type APC into SW480 colon cancer cells. These experiments identified a novel human gene, termed APCDD1, that was down-regulated in the cancer cells by exogenous wild-type APC; its expression was also reduced in response to transduction of AXIN1. Moreover, we documented elevated expression of APCDD1 in 18 of 27 primary colon cancer tissues compared with corresponding noncancerous mucosae. A reporter gene assay using the 5'-flanking region of APCDD1 indicated that transfection of beta-catenin together with wild-type Tcf4 into HeLa cells increased the reporter activity through two putative Tcf/lymphoid enhancer factor-binding motifs upstream of the transcription start site, indicating that APCDD1 is one of the direct targets of this transcription complex. Exogenous APCDD1 promoted growth of colon cancer cells both in vitro and in vivo, whereas transfection with antisense S-oligodeoxynucleotides decreased cell/tumor growth. These data suggest that APCDD1 is directly regulated by the beta-catenin/Tcf complex and that its elevated expression is likely to contribute to colorectal tumorigenesis.

Cell Division↗

PubMed2002

Isolation of HELAD1, a novel human helicase gene up-regulated in colorectal carcinomas.

To investigate the mechanisms of colorectal carcinogenesis, we searched for genes regulated by adenomatous polyposis coli gene product (APC) and identified a novel gene, termed HELAD1 (helicase, APC down-regulated 1). A recombinant polypeptide representing the ATPases associated with cellular activities (AAA) domain of the HELAD1 product showed 3' to 5' helicase activity and exonuclease activity in vitro. HELAD1 was abundantly expressed in 16 of 20 colon cancers examined but hardly detectable in corresponding non-cancerous mucosae. Treatment of colon-cancer cells with antisense oligonucleotides suppressed its expression and induced apoptosis. These data revealed an importance of HELAD1 in colorectal carcinogenesis and suggest that suppression of HELAD1 may be a promising therapeutic strategy.

Colorectal Neoplasms↗

PubMed2002

Cutaneous nerve to the subacromial region originating from the lateral pectoral nerve.

During dissection practice, a cutaneous branch to the deltoid region, which originated from the lateral pectoral nerve, was found bilaterally in one Japanese male (two of 125 sides, 1.6%). The branch originated from the superior surface of the lateral pectoral nerve, ran on the superior surfaces of the coracoid process and the coraco-acromial ligament, and pierced the deltoid muscle close to the tip of the acromion. The distribution area of this cutaneous branch was similar to the cutaneous branch of the suprascapular nerve. Although the branch from the suprascapular nerve has been reported in man and primates, a minute description of such a branch from the lateral pectoral nerve is not currently available in the literature. According to the detailed analyses of the roots of the lateral pectoral nerve and the suprascapular nerve, the roots of both nerves are close to each other in the upper part of the superior trunk of the brachial plexus. Therefore, these cutaneous branches have different courses, but are considered to be a single nerve to complement the supraclavicular nerves.

Cadaver↗

PubMed2002

Positional relationships between the masticatory muscles and their innervating nerves with special reference to the masseter and zygomaticomandibularis in Suncus murinus.

In the present study, we investigated the structure and nerve innervation of the masseter, temporalis and zygomaticomandibularis of Suncus murinus which has no zygomatic arch. Detailed dissection of eight head halves of four S. murinus was performed. In S. murinus, small muscle bundle was observed to be adjoined with the lateral surface of the temporalis. This muscle bundle was completely separated from the masseter. Based on the positional relationships between the muscle bundle and supplying nerves, we conducted that the bundle corresponded to the zygomaticomandibularis of human described in our previous study (Shimokawa et al., 1999). In addition, some differences in the nerve distribution to the masticatory muscles were observed in S. murinus as compared with humans with respect to the following points: 1) The additional supplying branch to the masseter originated from the auriculo-temporal nerve: 2) The common trunk of the masseteric nerve and the nerve to the posterior part of the temporalis penetrated the superior head of the lateral pterygoid. A possible model to account for these differences based on the positional relationships among the muscles and supplying nerves is presented.

Animals↗