Biomedical subjects

C Nishigori

Publications and source records attributed to C Nishigori.

At least 37 records · Page 2Linked to original sources

PubMed1996

Evidence that DNA damage triggers interleukin 10 cytokine production in UV-irradiated murine keratinocytes.

UV irradiation interferes with the induction of T cell-mediated immune responses, in part by causing cells in the skin to produce immunoregulatory cytokines. Recent evidence implicates UV-induced DNA damage as a trigger for the cascade of events leading to systemic immune suppression in vivo. However, to date, there has been no direct evidence linking DNA damage and cytokine production in UV-irradiated cells. Here we provide such evidence by showing that treatment of UV-irradiated murine keratinocytes in vitro with liposomal T4 endonuclease V, which accelerates the repair of cyclobutylpyrimidine dimers in these cells, inhibits their production of immunosuppressive cytokines, including interleukin 10. Application of these liposomes to murine skin in vivo also reduced the induction of interleukin 10 by UV irradiation, whereas liposomes containing heat-inactivated T4 endonuclease V were ineffective. These results support our hypothesis that unrepaired DNA damage in the skin activates the production of cytokines that down-regulate immune responses initiated at distant sites.

Animals↗

PubMed1996

DNA double strand breaks in epidermal cells cause immune suppression in vivo and cytokine production in vitro.

UV irradiation of the skin causes immune suppression by a mechanism involving epidermal cytokines. To determine the role of epidermal DNA damage in immune suppression, we used HindIII restriction endonuclease encapsulated in liposomes to cause DNA strand breaks in epidermal cells in vivo and in vitro. Topical application of HindIII in liposomes to murine skin in vivo impaired the induction of contact hypersensitivity responses initiated either locally or at distant sites and impaired the function of APCs. Unlike UV-B radiation, however, treatment of mice with HindIII in liposomes before contact sensitization did not induce tolerance or transferable suppression. The liposome-encapsulated HindIII caused double strand breaks in DNA and induced IL-10 and TNF-alpha production when added to cells of a murine keratinocyte line in vitro. Topical application of liposomal HindIII also induced TNF-alpha in the epidermis of mice. Liposomes containing heat-inactivated HindIII or an endonuclease specific for pyrimidine dimers in DNA did not exhibit these effects. These results support the hypothesis that DNA damage is a trigger for the production of cytokines that modulate immune responses. They also suggest that immune suppression and suppressor cell induction are separate consequences of cutaneous injury that require different stimuli.

Animals↗

PubMed1996

Characterization of p53 gene mutations in basal-cell carcinomas: comparison between sun-exposed and less-exposed skin areas.

Mutations in the p53 gene in 32 basal-cell carcinomas (BCC) developed in Japanese patients were identified by the polymerase chain reaction and single-strand-conformation polymorphism analysis, followed by sequencing the DNA. Among 16 BCC developed in continuously sun-exposed areas, 6 tumors showed 7 base substitutions, most of which were G:C to A:T transitions, mainly at the dipyrimidine sites. Seven out of 16 BCC developed in less-exposed areas showed 8 base substitutions, but the majority (75.0%) of them were transversions. These results suggest that the mutation in the p53 gene plays a significant role in the tumorigenesis of BCC developed in less-exposed areas as well as those in sun-exposed areas in Japanese patients. There must be therefore causative factors other than UV irradiation for BCC in less-exposed areas.

Aged↗

PubMed1996

Aberrant splicing and truncated-protein expression due to a newly identified XPA gene mutation.

A group A xeroderma pigmentosum (XPA) patient, XP2NI, is a compound heterozygote with a newly identified G to C transversion at the last nucleotide in exon 5 in one chromosome, and with the known splicing mutation in intron 3 in another chromosome in the XPA gene. XP2NI had mild skin symptoms and the cells were slightly less sensitive to UV radiation than the cells of typical severe XPA patients who have the splicing mutation in intron 3 homozygously. Reverse transcriptase (RT)-PCR and sequencing of the PCR products revealed that the mutation in exon 5 resulted in producing three types of aberrant mRNA, lacking 7 nucleotides at the end of exon 5, lacking entire exon 5, and lacking exons 3, 4 and 5. A significant amount of a truncated type of protein was produced in XP2NI cells, and the size of the protein indicated that it should have been translated from the mRNA, lacking the 7 nucleotides and retained one of the zinc-finger domains required for the DNA repair activity. The clinical mildness of XP2NI may be due to the residual DNA repair activity of the truncated XPA protein, while no XPA protein was detected in the XPA cells with the homozygous intron 3 splicing mutation.

Base Sequence↗

PubMed1996

8-hydroxy-2'-deoxyguanosine is increased in epidermal cells of hairless mice after chronic ultraviolet B exposure.

8-Hydroxy-2'-deoxyguanosine (8-OHdG) is a mutation-prone (G:C to T:A transversion) DNA base-modified product generated by reactive oxygen species or photodynamic action. G:C to T:A transversions are observed in the p53 and ras genes of UVB-induced skin cancers of mice and in squamous and basal cell carcinomas of human skin exposed to sunlight. In the current study, 8-OHdG formation was evaluated in the epidermis of hairless mice after repeated exposure to UVB, and possible mechanisms involved were studied. Exposure of hairless mice to either 3.4 [2 minimal erythema dose (MED)] or 16.8 (10 MED) kJ/m2 of UVB three times a week for 2 wk induced a 2.5- or 6.1-fold increase, respectively, in the levels of 8-OHdG in DNA, compared to the unexposed controls. An immunohistochemical method using a monoclonal antibody specific for 8-OHdG showed stronger and more extensive staining in the nuclei of UV-irradiated epidermal cells than in those of nonirradiated cells. Western blots probed with antibodies against 4-hydroxy-2-nonenal-modified proteins confirmed the involvement of reactive oxygen species in the epidermal damage induced by chronic UVB exposure. 3-Nitro-L-tyrosine was detected in western blots in a concentration-dependent manner, suggesting that peroxynitrite derived from the reaction of nitric oxide and superoxide, both of which were probably released from inflammatory cells, was involved in modifying the DNA bases. Therefore, the formation of 8-OHdG after UVB exposure appears to be regulated by at least three pathways: photodynamic action, lipid peroxidation, and inflammation and may play a role in sunlight-induced skin carcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1996

The immune system in ultraviolet carcinogenesis.

The immune system plays an important role in ultraviolet (UV) carcinogenesis by contributing to host resistance against skin cancer development. UV radiation, however, circumvents immune surveillance against skin cancers by modulating the immune response in a way that favors tumor development. Studies addressing the cellular mechanisms by which UV radiation modifies immune function are summarized. These studies demonstrate that UV irradiation of the skin produces both local, nonspecific immune suppression that inhibits immune effector functions within irradiated skin, as well as systemic, specific immune suppression against antigens introduced at a critical time after exposure to UV radiation. Evidence is presented suggesting that the production of cytokines by epidermal cells in response to UV-induced DNA damage is an important component of UV-induced specific immune suppression.

Animals↗

PubMed1995

High prevalence of mutations in the p53 gene in poorly differentiated squamous cell carcinomas in xeroderma pigmentosum patients.

Mutations in the p53 gene were analyzed in 23 squamous cell carcinomas (SCCs) and five basal cell carcinomas from 10 xeroderma pigmentosum patients in Tunisia. Fourteen mutations were detected. Most occurred at the dipyrimidine sequences of DNA, suggesting that they were caused by ultraviolet light. A strong correlation was noted between the presence of the p53 mutations and clinical characteristics such as histology and growth of SCC. In well-differentiated grade 1 SCCs, three (27.3%) of 11 tumors had the p53 gene mutations, whereas in grade 2 and grade 3 SCCs, six (85.7%) of seven tumors had the p53 gene mutations (p < 0.05). Tumors less than 8.0 mm in diameter showed a relatively low frequency of mutation (two of 10 tumors, 20.0%), whereas most of the tumors larger than 8.1 mm (seven of eight tumors, 87.5%) had mutations of the p53 gene (p < 0.025). Multiple tumors in the same xeroderma pigmentosum patients also showed this relation. These results suggest that mutations in the p53 gene lead to the invasive and rapid-growing character of SCC.

Adolescent↗

PubMed1994

Mutations in ras genes in cells cultured from mouse skin tumors induced by ultraviolet irradiation.

Mutations in ras oncogenes were detected in cultured cells of mouse skin tumors induced by near-UV irradiation. DNA extracted from the UV-induced tumor cells was transfected to golden hamster embryo cells, and focus-forming ability was confirmed in 22 of 26 cell strains, 15 of which had the repetitive mouse sequence. Mouse ras genes were detected in 10 of these 22 cell strains. Point mutations in the ras genes were at Ha-ras codon 13 (GGC-->GTC in two strains, GGC-->AGC in one strain), Ki-ras codon 61 (CAA-->GAA in two strains), and N-ras codon 61 (CAA-->CAT in two strains, CAA-->AAA in two strains). In one tumor cell strain no base change was directed. Most mutations occurred at dipyrimidine sites. Pyrimidine dimers or pyrimidine(6-4)pyrimidone photoproducts are the likely cause of the skin cancers. The base change occurred preferentially at G.C base pairs, and transversions predominated.

Animals↗

PubMed1994

Formation of 8-hydroxy-2'-deoxyguanosine in epidermis of hairless mice exposed to near-UV.

Six-week-old male albino hairless mice (Hos: Hr-1) were exposed to a near-ultraviolet (UV) fluorescent sun lamp (33.5 kJ/m2/hr; wave length > 270 nm with a peak at 312.5 nm) to investigate the induction of oxidative DNA damage in epidermal cells. Significantly higher levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) were detected in a dose-dependent manner in epidermis of mice exposed to near-UV than in those of control animals. The ratio of 8-OHdG in near-UV-exposed/unexposed control was 2.08 +/- 0.19 after 168 kJ/m2 exposure, P < 0.01; 3.49 +/- 0.36 after 335 kJ/m2 exposure, P < 0.01 (means +/- SE). The levels of 8-OHdG decreased with time after near-UV exposure, suggesting the presence of removal and/or repair mechanisms. This is the first report that oxidative DNA base modification is induced in vivo in epidermal cells by near-UV exposure. Oxidative DNA base modification may be one of the causes of sunlight-induced skin carcinogenesis.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1994

Far less frequent mutations in ras genes than in the p53 gene in skin tumors of xeroderma pigmentosum patients.

Mutations in Ha-ras, Ki-ras, and N-ras genes in squamous and basal cell carcinomas in patients with xeroderma pigmentosum (XP) were examined by the polymerase chain reaction followed by single-strand conformation polymorphism analysis and direct base sequencing. No mutation was detected in codons 12, 13, and 61 of the ras genes in XP skin tumors. This was in contrast with previous findings of a high frequency of mutation in the p53 gene in skin tumors in XP patients. A novel mutation in codon 6 of the Ki-ras gene was detected in a squamous cell carcinoma. The mutation was a C-->T transition at a dipyrimidine (5'-CT) sequence and could have been produced by solar ultraviolet light. The mutated ras gene did not have the ability to transform NIH/3T3 cells. In three tumors, multiple base substitutions were detected in exon 1 of the Ki-ras and N-ras genes. These results and our previous work on p53 gene mutations suggest that mutations in ras genes are far less frequent than in the p53 gene in the skin tumors in XP patients and that ras genes are less important in skin tumorigenesis in XP patients than is the p53 gene.

3T3 Cells↗

PubMed1994

Similarity in the molecular profile of mutations induced by UV light in shuttle vector plasmids propagated in mouse and human cells.

Shuttle vector plasmids pYZ289 were irradiated with UV and transfected to mouse cells to permit repair of damage, mutation and replication in the cells. The frequency and types of mutations were compared with those of UV-irradiated shuttle vector plasmids pZ189 which were propagated in normal human and xeroderma pigmentosum (XP) patient cells defective in DNA repair. Both shuttle vector plasmids contain a bacterial suppressor tRNA gene supF as a common mutation target. pYZ289 propagated in the mouse cells showed survival and mutation frequency similar to pZ189 propagated in the normal human cells. All single base substitution mutations were induced in dipyrimidine sequences and G:C to A:T transition was most frequently observed (47%) in the mouse cells; however, the frequency was significantly lower than that in the XP cells. The frequency of the base substitution mutations at A:T base pairs was significantly higher in the mouse cells (29%) than in the normal human (12%) and the XP cells (6%). These results show that similar types of mutations are induced by UV in mouse and normal human cells, and that the A:T base pair is relatively more mutable in mouse than in normal human and XP cells.

Animals↗

PubMed1994

Gene alterations and clinical characteristics of xeroderma pigmentosum group A patients in Japan.

BACKGROUND AND DESIGN: The responsible gene for xeroderma pigmentosum group A was recently identified. This study was performed to detect the gene alteration of xeroderma pigmentosum group A complementing gene in 29 xeroderma pigmentosum group A patients in Japan and to analyze whether genetic alterations in the xeroderma pigmentosum group A complementing gene are related to the clinical features. RESULTS: Of 29 patients, 25 (86%) had a mutation at the splicing junction of intron 3 and exon 4 in the homozygous state that was detected by the polymerase chain reaction and the AlwN I-restriction fragment length polymorphism. Patients having a splicing mutation at intron 3 in the homozygous state develop severe skin manifestations from early infancy and severe progressive neurologic abnormalities, including sensorineural hearing impairment, brain atrophy, mental retardation, areflexia, and ataxia. Four patients were heterozygous for splicing mutation in intron 3. Among them, at least three patients showed milder skin symptoms and milder neurologic abnormalities than patients with the homozygous splicing mutation. Two patients (single-ovum twins) revealed a compound heterozygote of splicing mutation of intron 3 and a nonsense mutation of exon 6. One patient had the splicing mutation and another mutation at the last codon of exon 5, a type of mutation that has never been reported. CONCLUSION: These data indicate that different genetic alterations in the xeroderma pigmentosum group A complementing gene may induce different clinical features.

Adolescent↗

PubMed1993

Ultraviolet-specific mutations in p53 gene in skin tumors in xeroderma pigmentosum patients.

Mutations in the p53 gene were identified in five of eight non-melanoma skin tumors in the sun-exposed areas of xeroderma pigmentosum patients by the polymerase chain reaction and single strand conformation polymorphism analysis followed by sequencing of the DNA. All mutations occurred at the dipyrimidine sites, indicating that they were caused by UV irradiation. Two tumors had multiple mutations, and four tumors had nonsense mutations. Since xeroderma pigmentosum patients are extremely sensitive to UV, the solar UV should have caused the mutations in the p53 gene and the mutations must have played a significant role in UV tumorigenesis.

Adolescent↗

PubMed1993

IgG4 deficiency with Rothmund-Thomson syndrome: a case report.

We describe a patient with Rothmund-Thomson syndrome and IgG4 deficiency. In vitro examination of his peripheral mononuclear cells revealed impaired IgG4 synthesis. Susceptibility to sinus and pulmonary infections was cured by monthly immunoglobulin infusions.

Child, Preschool↗

PubMed1993

Absence of DNA repair deficiency in the confirmed heterozygotes of xeroderma pigmentosum group A.

This study was performed to elucidate whether xeroderma pigmentosum complementation group A (XPA) carrier has DNA repair abnormality against sun-exposure and ultraviolet (UV)-mimetic chemical carcinogen 4-nitroquinoline 1-oxide (4NQO). Here we report three sporadic cases of XP that were defined as group A by genetic complementation test as well as polymerase chain reaction (PCR) analysis to detect the point mutation in the responsible gene for XPA. DNA repair analyses in the skin fibroblasts revealed that the cells from the patients were much more sensitive to UV and 4NQO and had extremely low UV-induced unscheduled DNA synthesis (UDS) than control cells, whereas the cells from the carriers (heterozygotes of XP) had sensitivity to UV and 4NQO and levels of UV-induced UDS similar to normal cells. These results indicate that the obligate heterozygotes, despite having a mutated allele in XPA complementing gene demonstrated by PCR, have no DNA repair abnormality after UV irradiation and UV-mimetic 4NQO treatment. Our observations imply that XPA heterozygotes do not have higher risk of skin cancers than normal subjects based on their DNA repair abnormality.

4-Nitroquinoline-1-oxide↗

PubMed1993

A case of xeroderma pigmentosum complementation group F with neurological abnormalities.

We report a 48-year-old Japanese man suffering from xeroderma pigmentosum associated with mental retardation, cerebral atrophy and cerebellar ataxia. Cultured fibroblasts from an unexposed area of skin had reduced DNA repair capacity after UV irradiation, with higher sensitivity to UV than normal cells in colony-forming ability and host cell reactivation using herpes simplex virus. Genetic complementation tests by cell fusion with polyethylene glycol revealed that the patient belonged to group F. He died of bile duct cancer at the age of 50. This is the first report of an XP-F patient with neurological abnormalities.

Brain Diseases↗

PubMed1993

High prevalence of the point mutation in exon 6 of the xeroderma pigmentosum group A-complementing (XPAC) gene in xeroderma pigmentosum group A patients in Tunisia.

Xeroderma pigmentosum (XP) patients in Tunisia who belong to the genetic complementation group A (XPA) have milder skin symptoms than do Japanese XPA patients. Such difference in the clinical features might be caused by the difference in the site of mutation in the XP A-complementing (XPAC) gene. The purpose of this study is to identify the genetic alterations in the XPAC gene in the Tunisian XPA patients and to investigate the relationship between the clinical symptoms and the genetic alterations. Three sites of mutation in the XPAC gene have been identified in the Japanese XPA patients, and about 85% of them have a G-->C point mutation at the splicing acceptor site of intron 3. We found that six (86%) of seven Tunisian XPA patients had a nonsense mutation in codon 228 in exon 6, because of a CGA-->TGA point mutation, which can be detected by the HphI RFLP. This type of mutation is the same as those found in two Japanese XPA patients with mild clinical symptoms. Milder skin symptoms in the XPA patients in Tunisia than in those in Japan, despite mostly sunny weather and the unsatisfactory sun protection in Tunisia, should be due to the difference in the mutation site.

Adolescent↗

PubMed1993

A case of Rothmund-Thomson syndrome with reduced DNA repair capacity.

BACKGROUND: Rothmund-Thomson syndrome is an autosomal recessively inherited disease with multiple skin disorders, and little has been known about the cause of the clinical features. We cultured the cells from a patient with Rothmund-Thomson syndrome and examined the ultraviolet repair characteristics. OBSERVATIONS: A 5-year-old boy with Rothmund-Thomson syndrome is presented. He has had reticular pigmentation and hypopigmentation on his cheeks, upper aspect of the trunk, palms, and soles since 6 months of age. Cells originating from the patient had reduced unscheduled DNA synthesis, 37% of normal, after exposure to ultraviolet C (predominantly at 254 nm), and they were slightly more sensitive to ultraviolet C than were normal cells in cell ultraviolet survival. CONCLUSION: Such repair deficiency might account for the mild sun sensitivity in early childhood. Heterogeneity in the repair mechanism as well as in clinical features in this syndrome was suggested.

Cells, Cultured↗