Study Protocol of a Comprehensive Activity Promotion Program for the Prevention of Dementia: A Randomized Controlled Trial Protocol

BACKGROUND

Several technical devices are available to monitor and promote changes in behavior toward higher activity. In particular, smartphones are becoming the primary platform for recognizing human activity. However, the effects of behavior change techniques that promote physical, cognitive, and social activities on incident dementia in older adults remain unknown.

OBJECTIVES

This randomized controlled trial aims to examine the effects of behavior change techniques on the prevention of dementia among community-dwelling older adults using a smartphone as a behavior change tool.

DESIGN

A randomized controlled trial.

SETTING

Community in Japan.

PARTICIPANTS

The study cohort comprises 3,498 individuals, aged ≥60 years, randomized into two groups: the smartphone group (n = 1,749) and the control group (n = 1,749).

INTERVENTION

The smartphone group will be asked to use smartphone applications for at least 30 minutes daily to self-manage and improve their physical, cognitive, and social activities. The smartphone group will perform 60-minute group walking sessions using application-linked Nordic walking poles with cognitive stimulation twice a week during the intervention period. The walking poles are a dual-task exercise tool that works with a smartphone to perform cognitive tasks while walking, and the poles are equipped with switches to answer questions for simple calculation and memory tasks. The smartphone and control groups will receive lectures about general health that will be provided during the baseline and follow-up assessments.

MEASUREMENTS

Incident dementia will be detected using cognitive tests (at baseline, after 15 months, and after 30 months) and by preparing diagnostic monthly reports based on data from the Japanese Health Insurance System. Participants without dementia at baseline who will be diagnosed with dementia over the 30-month follow-up period will be considered to have incident dementia.

CONCLUSIONS

This study has the potential to provide the first evidence of the effectiveness of information communication technology and Internet of Things in incident dementia. If our trial results show a delayed dementia onset for self-determination interventions, the study protocol will provide a cost-effective and safe method for maintaining healthy cognitive aging.

Association of Daily Physical Activity with Disability in Community-Dwelling Older Adults With/Without Chronic Kidney Disease

OBJECTIVES

Physical activity is recommended for disability prevention in the older adult population; however, the level of physical activity required for older adults with chronic kidney disease (CKD) remains unknown. This study aimed to examine the associations between daily physical activity and disability incidence in older adults with and without CKD to determine relevant daily physical activity levels.

DESIGN

Prospective observational study.

SETTING AND PARTICIPANTS

3,786 community-dwelling older adults aged ≥65 years.

MEASUREMENTS

Mean daily times spent in light- (LPA) and moderate-to-vigorous physical activity (MVPA) were measured using triaxial accelerometers. CKD was defined by a creatinine estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2. Disability incidence was identified as long-term care insurance certification during a 60-month follow-up period. Associations between physical activity and disability incidence were examined using Cox proportional hazard models stratified by the CKD status. Non-linear and linear associations were tested using the restricted cubic spline.

RESULTS

A total of 1,054 individuals were identified to have CKD. Disability incidence was higher in the CKD group than in the non-CKD group. The adjusted cox proportional hazard models indicated that a 10-minute increase in MVPA time was associated with lower disability incidence in the non-CKD group (hazard ratio [HR], 0.838; 95% confidence interval [CI]: 0.764-0.918) and the CKD group (HR, 0.859; 95% CI: 0.766-0.960). Linear associations were observed in MVPA for the non-CKD and CKD groups.

CONCLUSION

Increasing MVPA was associated with lower disability incidence in older adults with and without CKD. These findings can help devise disability prevention strategies for older CKD patients.

Association between Non-Face-to-Face Interactions and Incident Disability in Older Adults

OBJECTIVES

This observational prospective cohort study, conducted between September 2015 and February 2019, aimed to investigate the association between the incidence of disability and non-face-to-face interactions among community-dwelling older adults in Japan.

DESIGN

Participants reported their interaction status using a self-report questionnaire. Face-to-face interactions comprised in-person meetings, while virtual interactions (e.g., via phone calls or emails) were defined as non-face-to-face interactions. We examined the relationship between their interaction status at baseline and the risk of disability incidence at follow-up. We also considered several potential confounding variables, such as demographic characteristics.

SETTING

The National Center for Geriatrics and Gerontology-Study of Geriatric Syndromes.

PARTICIPANTS

We included 1159 adults from Takahama City aged ≥75 years (mean age ± standard deviation = 79.5 ± 3.6 years).

MEASUREMENTS

Interaction status was assessed using a self-reported questionnaire consisting of two sections (face-to-face and non-face-to-face interactions), and four questionnaire items. Based on the responses we categorized study participants into four groups: "both interactions," "face-to-face only," "non-face-to-face only," and "no interactions."

RESULTS

Individuals with both kinds of interactions (49.3/1000 person-years) or only one kind of interaction (face-to-face = 57.7/1000 person-years; non-face-to-face = 41.2 person-years) had lower incidence of disability than those with no interactions (88.9/1000 person-years). Moreover, the hazard ratios adjusted for potential confounding factors for the incidence of disability in the both interaction, face-to-face-only, and non-face-to-face only groups were 0.57 (confidence interval = 0.39-0.82; p = 0.003), 0.66 (confidence interval = 0.44-0.98; p = 0.038), and 0.47 (confidence interval = 0.22-0.99; p = 0.048), respectively.

CONCLUSION

Considering the interaction status of older adults in their day-to-day practice, clinicians may be able to achieve better outcomes in the primary prevention of disease by encouraging older adults to engage in any form of interaction, including non-face-to-face interactions.

Visceral Fat Accumulation Is Associated with Mild Cognitive Impairment in Community-Dwelling Older Japanese Women

OBJECTIVES

Visceral fat accumulation is detrimental for brain health and is associated with cognitive impairment in older adults. The objectives of the present study were to examine the association between visceral fat accumulation and prevalence of mild cognitive impairment and its subtypes.

DESIGN

a cross-sectional study.

PARTICIPANTS

This study enrolled 6,109 community-dwelling older adults, including 3,434 women (mean age: 74.4 years) and 2,675 men (mean age: 74.3 years). Individuals with dementia, Parkinson's disease, stroke, Mini-Mental State Examination scores ≤23, and who could not perform basic activities of daily living independently were excluded.

MEASUREMENTS

Participants underwent neurocognitive assessments to assess mild cognitive impairment (MCI) and its subtypes. Visceral fat area (VFA) was measured using abdominal bioelectrical impedance analysis. Participants were divided into quartile groups by VFA.

RESULTS

There were 731 (21.3%) women and 562 (21.0%) men with MCI, and the median VFA values were 63.3 cm2 and 96.3 cm2, respectively. Women participants in the second (adjusted odds ratios [aOR], 0.71; 95% confidence interval [95% CI], 0.54-0.94), third (aOR, 0.66; 95% CI, 0.47-0.92), and fourth quartiles of VFA (aOR, 0.62; 95% CI, 0.41-0.93) had a significantly lower risk of MCI than those in the first quartile. Higher VFA quartiles in women were associated with lower risk of non-amnestic MCI. There were no significant differences in men between quartiles.

CONCLUSIONS

Visceral fat accumulation was associated with MCI, especially non-amnestic MCI, in community-dwelling older Japanese women. These results suggest that visceral fat accumulation is partially protective against cognitive impairment.

P450 in wild animals as a biomarker of environmental impact

The impact of environmental pollution on selected animals was tested by monitoring the hepatic content of cytochromes P450 and their enzyme activities or by calculating TEQ values from the concentration of pollutants in the body. Fish-eating Stellars Sea Eagles, Haliaeetus pelagicus, found dead in the northern part of Hokkaido island accumulated high levels of PCBs and DDT and metabolites. The TEQ values calculated from the PCB concentration in the eagles were high enough to cause a significant toxic effect in other birds living in the same environment. Some of these birds were also contaminated with high concentrations of lead. Spotted seals, Phoca largha, captured along the coast-line of Hokkaido accumulated PCBs in their fat at about 100 million times the concentrations in the surface sea water. The levels of expressions of hepatic microsomal CYP 1A1and related enzyme activities in these seals showed good correlation to the levels of PCBs accumulated in the fat. The fresh water crabs, Eriocheir japonicus, were captured from three different rivers with various degrees of pollution. The P450 content and the related enzyme activities showed good correlation to TEQ values obtained from the concentrations of PCBs and PCDDs in the crabs from the rivers. The wild rodents, Clethrionomys rufocanus, were captured from urban, agricultural, and forest areas in Hokkaido. Those from the forest area had the lowest CYP content and related enzyme activities, comparable to those in laboratory-raised animals. Those from the urban areas, presumably contaminated with PAHs from fuel combustion, showed increased CYP 1A1 content and related enzyme activities. Those from the agricultural areas showed increased levels of CYP 1A1, 2B, 2E1. Rats treated with some of the agrochemicals used in the area resulted in a similar pattern of induction. It is concluded that P450 can be a useful biomarker for assessing the environmental impact of chemical pollutants on wild animals.

RT-PCR-based cytochrome P450 expression profile of oral tissue samples1

OBJECTIVE

To analyse the expression of individual forms of cytochrome P450 (CYP) at the mRNA level in five homogenized oral buccal tissue samples from four individuals with or without oral malignancy.

METHOD

Individual forms of CYPs were studied by reverse transcriptase-polymerase chain reaction (RT-PCR), using specific primers for CYPs 2B6, 2C, 2D6, 2E1, 3A3/4 and 3A5, and oral CYP expressions were compared with CYP expression in liver tissue.

RESULTS

Consistent expression of CYPs 2C, 2E1 and 3A5 was observed in oral buccal tissue at mRNA level.

CONCLUSIONS

These particular CYPs have possible roles in the protection of the body against orally ingested xenobiotics as well as influence the bioavailability of therapeutic compounds.

Frequent expression of new cancer/testis gene D40/AF15q14 in lung cancers of smokers

We found a significant correlation between lung cancer in smokers and the expression of a human gene, D40, predominantly expressed in testis and cancers. In an attempt to clone a novel human gene, we screened a cDNA library derived from a human B cell line and obtained a cDNA clone that we refer to as D40. A search for public databases for sequence homologies showed that the D40 gene is identical to AF15q14. D40 mRNA is predominantly expressed in normal testis tissue. However, this gene is also expressed in various human tumour cell lines and primary tumours derived from various organs and tissues, such as lung cancer. We examined the relationship between D40 expression and clinico-pathological characteristics of tumours in primary lung cancer. D40 expression did not significantly correlate with either histological type or pathological tumour stage. However, D40 expression was observed more frequently in poorly differentiated tumours than in well or moderately differentiated ones. Furthermore, the incidence of D40 expression was significantly higher in tumours from patients who smoke than in those from non-smokers. D40/AF15q14 is the first gene in the cancer/testis family for which expression is related to the smoking habits of cancer patients.

Negative correlation between plasma thyroid hormone levels and chlorinated hydrocarbon levels accumulated in seals from the coast of Hokkaido, Japan

Chlorinated hydrocarbon (CHC) levels in the blubber of larga seals (Phoca largha) and ribbon seals (Phoca fasciata) collected from the coastal waters of Hokkaido, Japan, were determined in order to assess the hormonal effects of CHC exposure in free-ranging pinnipeds. Plasma thyroid hormone levels, including total thyroxine (T4), free thyroxine (free T4), total triiodothyronine (T3), and free triiodothyronine (free T3), were also measured. Higher concentrations of polychlorinated biphenyl congeners (PCBs), dichlorodiphenyltrichloroethane and its metabolites, and chlordane compounds were found in the range of 380 to 2,600 ng/g, 350 to 2,600 ng/g, and 120 to 760 ng/g on a wet-weight basis, respectively. Spearman rank correlation analyses showed that in larga seals, plasma total T3 and free T3 levels negatively correlated with levels of all the CHCs analyzed, although there was no such correlation between total or free T4 levels and CHC concentrations. In ribbon seals, total T3 levels significantly decreased with an increase of di-ortho PCB (PCB170 and 180) residues. These findings indicated that the plasma T3 deficiency could be associated with some CHC exposure in larga and ribbon seals and that the responses of plasma thyroid hormones may be useful biomarkers for CHC exposure in ribbon seals.

Multiple oral squamous epithelial lesions: are they genetically related?

The development of second primary tumors (SPTs) in patients with head and neck squamous cell carcinoma (HNSCC) has become an increasingly important factor in clinical treatment decisions. Currently, clinical and histologic parameters are used to determine whether or not SPT is present. Recent studies suggest that many SPTs in the upper aerodigestive tract have a common clonal origin, challenging the longstanding multiclonal origin concept. To determine genetic relationships among multiple oral cancerous and precancerous lesions (MOCP), we analysed 100 lesions from 26 Japanese patients. Lesion development was synchronous and metachronous. We looked for patterns of microsatellite alterations (MA) using seven markers at chromosomes 3p14, 9p21, and 17p13, where MA occurs early in oral carcinogenesis. Loss of heterozygosity (LOH) was found in 52.6% (41/78), 62.5% (60/96), and 59.3% (32/54) of informative MOCP at 3p14, 9p21, and 17p13, respectively. Microsatellite instability (MI) was observed in 11, 26 and 13% of the samples at 3p14, 9p21, and 17p13 markers, respectively. Patterns of MA were concordant in only nine (14%) of 63 lesions from four (18%) of 22 patients who initially presented with noninvasive lesions. However, two of four patients with invasive cancer as indexed lesion showed 16 (43%) clonally related MOCP among 37 lesions (P=0.003). The results suggest that the majority of MOCP arise from clonally independent cells affected by field cancerization. However, the probability of mucosal spread of clonal malignant or premalignant cells may increase along with malignant progression.

Identification of novel cytochrome P450 1A genes from five marine mammal species

Marine mammals, being endangered by the chronic exposure of hydrophobic environmental contaminants as an assorting result of global pollution, are especially focused as indicators for organochlorine pollution. The use of contaminant-induced xenobiotic metabolizers, particularly P450 (CYP) 1A, in marine mammals can be effective as potential biomarkers of the contaminant exposure and/or toxic effects. In this study, we identified the first marine mammalian CYPs. Six novel CYP1A cDNA fragments were cloned from the livers of marine mammal species, minke whale (Balaenoptera acutorostrata), dall's porpoise (Phocoenoides dalli), steller sea lion (Eumetopias jubatus), largha seal (Phoca largha), and ribbon seal (Phoca fasciata) by the method of reverse transcription/polymerase chain reaction (RT/PCR); two distinct fragments were from steller sea lion and one fragment each was obtained from the other species. Five of the fragments, one from each species, were classified in the subfamily of CYP1A1, and the other fragment cloned from steller sea lion was designated CYP1A2. Degenerate PCR primers were used to amplify the fragments from liver cDNAs. The deduced amino acid sequences of these fragment CYP1As showed identities ranging from 50.0 to 94.3% with other known vertebrate CYPs in the subfamily of CYP1A, including those from fish, chicken, and terrestrial mammals. The isolated fragments were used to construct a molecular phylogeny, along with other vertebrate CYP1A cDNAs cut down in size to the corresponding region of 265 bp in which those newly determined fragments were cloned. This phylogenetic analysis by the maximum parsimony method using the PHYLIP program suggests two distinct evolutional pathways for aquatic mammalian CYP1As, compatible to a conservative taxonomy. Pinniped genes are clustered together with dog gene, forming a carnivore group, and cetaceans form another branch. Identification of CYP1A genes in marine mammals will be an introductory step to provide new insights into the metabolic or toxicological functions of CYP1As in these animals.

Characteristics of mutations in the p53 gene of oral squamous-cell carcinomas associated with betel-quid chewing in Sri Lanka

Oral squamous-cell carcinoma (SCC) is the most common neoplasm in Sri Lanka, accounting for approximately 30% of all cancers in males. Epidemiologic evidence indicates that there is an unequivocal relationship between betel chewing and oral carcinogenesis, suggesting that there may be specific genetic targets of betel-quid ingredients. The p53 gene has been indicated to be a tumor-suppressor gene that is found in mutated form in common human cancers; however, there are few reports about "carcinogen-specific" p53 mutation. Because of this background, primary resected specimens from 23 oral SCCs, 7 leukoplakias and 2 oral submucous fibrosis were collected from oral SCC patients in Sri Lanka and were used for p53 mutation analysis. Exons 5 through 8 of the p53 gene were examined by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and direct sequencing. Mutations in the p53 gene were frequent (10/23) in oral SCC specimens from Sri Lanka. Moreover, the mutations clustered significantly in exon 5 (7/10) of the p53 gene, and small deletions and inclusions other than point mutations were observed. These results indicate that 1) betel-quid chewing may cause specific genetic changes, including mutation in the p53 gene; 2) mutations in the p53 gene are not rare events in SCC patients who are betel-quid chewers, which contrasts with other reports; 3) exon 5 of the p53 gene could be one of the specific targets for some betel-quid ingredients; and 4) betel-quid chewing may be a critical environmental factor in the development of oral SCC.

High frequency of p53 mutations in human oral epithelial dysplasia and primary squamous cell carcinoma detected by yeast functional assay

To determine the timing and actual incidence of p53 mutations in oral epithelial lesions, we examined 33 primary squamous cell carcinomas (SCCs), 14 dysplasias and six hyperplasias from Japanese patients by a combination of yeast functional assay and DNA sequencing. The assay detects mutations of p53 mRNA between codons 67 and 347 on the basis of the DNA-binding activity of the protein. Twenty-six SCCs (79%) and five dysplasias (36%) were positive for p53 mutation, while all six hyperplasias were negative for the mutation. Human papillomavirus type 16 E6 mRNA was detected in one of seven p53 mutation-negative SCCs by reverse transcription polymerase chain reaction (RT-PCR). We further examined p53 mutations in 17 Sri Lankan oral SCCs using the yeast functional assay and the single-strand conformation polymorphism analysis of PCR-amplified DNA fragments (PCR-SSCP) of exon 5-8. The mutations were confirmed by DNA sequencing and the detection sensitivity was compared between the two methods. Six samples (35%) were positive for p53 mutation in PCR-SSCP analysis, while nine samples (53%) were positive in yeast functional assay. This suggests that the incidence of p53 mutations has been considerably underestimated in the conventional SSCP analysis. The present data indicate that p53 mutations are extremely frequent in oral cancers in the Japanese, and suggest that the timing and significance of p53 mutation in oral tumor progression vary in different ethnic populations and areas.

Enhancement of tumor associated antigen expression during the regression phase of xenogenized tumor cell growth in vivo

Rat fibrosarcoma cells infected with Friend leukemia virus (FV-KMT-17) grow for a short time and then regress spontaneously in syngeneic hosts. This regression was caused by immunological mechanisms, because the tumor cells were renogenized. In this study, we have tried to find out whether tumor-associated antigen (TAA) expression in these xenogenized tumor cells can be modulated by xenogenization. FV-KMT-17 cells (1 x 10(7)), which were subcutaneously transplanted into ten rats, spontaneously regressed after temporary growth. All rats which rejected FV-KMT-17 cells showed strong resistance to rechallenge with KMT-17 (1 x 10(6)) cells. To reveal the chronological modulation of TAA and virus-associated antigen (VAA), a single-cell suspension was obtained from the subcutaneous tumors and expression of these antigens was chronologically measured. TAA, termed CE7 antigen, was examined by anti-CE7 monoclonal antibody (MoAb) and VAA was examined by anti-FK1 MoAb which recognizes the FV env gene product (gp 70). Expression of VAA was not modulated through either the progression or the regression phase, but expression of TAA was strongly enhanced in the regression phase. These results show that enhancement of TAA expression occurs during the regression phase of FV-KMT-17 growth in vivo and that TAA-expressing cells may stimulate anti-tumor immunity, resulting in acquisition of resistance against parental KMT-17 cells.

Enhancement of tumor antigen expression and inhibition of pulmonary metastasis of rat fibrosarcoma cells by local radiotherapy

Pulmonary metastasis formation after local radiotherapy against a rat fibrosarcoma was investigated. KMT-17 fibrosarcoma cells were transplanted into the hind leg in syngeneic WKA rats and two different doses (30Gy, 60Gy) of irradiation from a 60Co source were applied 5 days after transplantation. Pulmonary metastasis was inhibited by 30Gy irradiation rather than 60Gy irradiation, which was enough to almost completely cure the local tumors. This inhibitory effect of 30Gy irradiation was induced by the continued presence of irradiated tumors. As for pulmonary metastasis, the different effects of irradiation doses were not recognized when the tumor was removed surgically 1 day after irradiation, but when it was removed 4 days after 30Gy irradiation significantly inhibited metastasis. Expression of tumor-associated antigen (TAA), termed CE7 antigen, on the cell surface was enhanced effectively and continuously by 30Gy irradiation rather than by 60Gy. With this increase in CE7-expressing cells, the enhancement of anti-tumor immunity of spleen cells was observed in an in vitro 125I-IudR release assay and an in vivo tumor-neutralizing assay (Winn assay). The above results suggest that an appropriate dose of irradiation such as 30Gy, to a local tumor can efficiently enhance the TAA expression and that TAA-expressing cells may stimulate anti-tumor immunity, resulting in inhibition of pulmonary metastasis. This phenomenon may offer the possibility of resistance to micrometastasis through the induction of antitumor effector cells.

Mutations in the p53 gene and human papillomavirus infection as significant prognostic factors in squamous cell carcinomas of the oral cavity

The p53 gene has been indicated to be a tumour suppressor gene that is found in mutated form in common human cancers. Human papillomavirus (HPV) has oncogenic activity in cervical and oral squamous cell carcinomas (SCCs). The E6 protein of HPV is known to bind with p53 protein and inactive the tumor suppressor activity by promoting p53 degradation. Because of this background, we examined 38 primary, resected specimens of oral SCCs for detection of p53 mutations and HPV DNAs. Exons 5 through 8 of the p53 Mutations were observed in nine cases (24%). HPV-DNA detection and typing were performed using PCR with ¿high risk group' HPV-specified primers. HPV DNA sequences were detected in eight cases (21%). The AvaII digestion pattern of PCR-amplified HPV DNA showed that HPV-16 was present in all eight cases. Seven cases were p53 mutation-positive/HPV-negative, six cases were p53 mutation-negative/HPV-positive, and two intraosseus SCC cases were p53 mutation-positive/ HPV-positive. Thus, 15/38 (40%) cases had inactivation of the p53 protein. Interestingly, p53 mutation-negative/ HPV-negative cases had a poorer prognosis than p53 mutation positive or HPV-positive cases (P < 0.01). We conclude that (1) mutation in the p53 gene and/or HPV infection are frequent (40%) in oral SCC; (2) inactivation of p53 function by mutation and HPV infection are important genetic events in the development of 40% integral of oral SCCs; (3) p53 mutation and HPV infection are not mutually exclusive events and (4) other oncogenes or tumor suppressor genes may be crucial in the development of oral SCC if the prognosis is poor.

Modulation of the rat tumor-associated shedding antigen (CE7) and augmentation of immunogenicity by irradiation

We have previously reported that rat fibrosarcoma KMT-17 cells and their in vitro counterparts, cloned A3 cells, shed a tumor-associated antigen (TAA), termed CE7, from the cell surface on vesicular membranes, under growth-enhancing conditions. This study shows that irradiation (1 approximately Gy) from a 60Co source, inhibited A3 cell growth dose-dependently and correspondingly increased CE7 expression by A3 cells as determined by anti-CE7 monoclonal antibody using flow cytometry. CE7 expression gradually increased with increasing doses of irradiation and reached a peak level at 30Gy. After 30Gy irradiation, CE7 expressing A3 cells were fixed with 1% paraformaldehyde and were used to intradermally immunize syngenic rats. Immunized rats developed transplantation resistance to the parent KMT-17 cells as compared to rats immunized with unirradiated A3 cells. Rat MHC class 1 antigen expression was slightly decreased by irradiation and therefore, resistance to tumor transplantation appeared to arise solely due to the enhancing effects of irradiation on TAA expression which increases the antigenicity of the tumor cells coverting them to an effective stimulator of antitumor effector cells. This phenomenon may offer a possibility of the resistance to the re-emergence and metastasis of the tumor like a KMT-17 through the induction of antitumor memory cells.

Detection of human papillomavirus DNA sequences in oral squamous cell carcinomas and their relation to p53 and proliferating cell nuclear antigen expression

BACKGROUND

The etiology of oral squamous cell carcinoma (SCC) is still obscure. Since human papillomavirus (HPV) DNAs are associated with carcinoma of the uterine cervix, carcinomas of the oral cavity were investigated to ascertain if these viruses are present in squamous carcinomas of this anatomic site.

METHODS

Seventy-seven oral mucosal SCCs were examined for the presence of HPV DNAs by polymerase chain reaction and dot blot hybridization. Immunohistochemical detection of proliferating cell nuclear antigen (PCNA) and p53 was performed and single strand conformation polymorphism analysis for p53 was undertaken. In situ hybridization detection of HPV-16 DNA also was performed.

RESULTS

Human papillomavirus-16 DNA was detected in 23 cases of oral SCC and both HPV-16 and HPV-18 DNA were detected in one case of tongue SCC. Human papillomavirus DNAs were detected of 11 of 33 tongue, 4 of 15 gingival, 2 of 4 palate, 2 of 5 buccal mucosa, 3 of 7 maxillary sinus, and 2 of 11 the floor of the mouth SCCs. None were detected in SCCs of the retromolar region (0/2). Immunohistochemical examination for p53 was performed in 26 cases of oral SCC and the accumulation of p53 protein was observed in 6 cases (i.e., in 4 of 17 HPV DNA-negative cases and in 2 of 9 HPV DNA-positive cases). Single strand conformation polymorphism analysis confirmed gene mutations in all 6 cases. Human papillomavirus-16 DNA was predominantly identified in cancer cells that showed a morphologic resemblance to basal cells and its hybridized signal in keratinized cells was reduced by in situ hybridization detection. Immunohistochemical detection of PCNA revealed its cooccurrence with HPV-16 DNA in cancer cells.

CONCLUSIONS

These results suggest that HPV-16 DNA sequences may have the capability to maintain the proliferative state of epithelial cells, and may contribute to the production of malignant phenotypes.

p53 immunostaining positivity is associated with reduced survival and is imperfectly correlated with gene mutations in resected non-small cell lung cancer. A preliminary report of LCSG 871

We investigated the correlation of p53 abnormalities with survival in 85 patients with non-small cell lung cancer (NSCLC) who had undergone resection with curative intent as part of Lung Cancer Study Group (LCSG) 871. Our previous studies showed that only a subset of p53 mutations in lung cancers result in overexpression. In addition, protein overexpression has been described in the absence of mutation. Therefore, we determined both p53 protein overexpression (by immunostaining) and p53 and ras gene mutations (by single-strand conformation polymorphism and DNA sequencing) in this set of resected tumor specimens. Clinical follow-up data were available for 75 cases. Of the studied patients, 64% showed p53 overexpression and 51% had mutant p53 sequences; however, the concordance rate was only 67%. There was a negative survival correlation with positive p53 immunostaining (p = 0.05), but not with the presence of gene mutations (p = 0.62) in this group of patients. Overexpression of p53 protein determined by immunostaining may contribute to adverse outcome due to the ability of p53 to act as a dominant oncogene, or alternatively, overexpression may reflect ongoing DNA damage in the tumor as a marker for a more aggressive behavior. When adjusted for stage, age, and gender by multivariate analysis, however, there was no independent impact of p53 overexpression on survival.

Modulation of the shedding of a rat tumor-associated antigen by growth regulation and anti-cancer drugs

CE7 antigen is shed from A3 cell surfaces by cells grown in medium containing a sufficient (10%) amount of fetal calf serum (FCS), but shedding of the antigen decreases with a decrease in FCS content in the culture medium. However, the cells contain similar amounts of antigen as evidenced by Western blotting, indicating that low FCS levels interfere with antigen shedding but not antigen synthesis. Antigen expression by A3 cells treated with mitomycin C gradually shifted from negative to a strong positive with time, and on day 2, two peaks corresponding to negative and positive cells within the population can be observed. In contrast, A3 cells treated with bleomycin and cyclophosphamide shifted as a whole from negative to weakly positive. When A3 cells in media containing 10% FCS were incubated at 4 degrees C, although the cells did not proliferate, antigen expression could not be detected by flow cytometry.

Hereditary and acquired p53 gene mutations in childhood acute lymphoblastic leukemia

The p53 gene was examined in primary lymphoblasts of 25 pediatric patients with acute lymphoblastic leukemia by the RNase protection assay and by single strand conformation polymorphism analysis in 23 of 25 cases. p53 mutations were found to occur, but at a low frequency (4 of 25). While all four mutations were identified by single strand conformation polymorphism, the comparative sensitivity of RNase protection was 50% (2 of 4). Heterozygosity was retained at mutated codons in 3 of 4 cases. One pedigree was consistent with the Li-Fraumeni syndrome, and bone marrow from both diagnosis and remission indicated a germline G to T transversion at codon 272 (valine to leucine). Although members of another family were affected with leukemia, a 2-bp deletion in exon 6 was nonhereditary. The other two nonhereditary p53 mutations included a T to G transversion at codon 270 (phenylalanine to cysteine) and a G to C transversion at codon 248 (arginine to proline). These data support the role of both hereditary and acquired p53 mutations in the pathogenesis and/or progression of some cases of childhood acute lymphoblastic leukemia.

Temperature-sensitive mutants of p53 associated with human carcinoma of the lung

We have compared the effects of specific point mutations on the tertiary and quaternary structure of the human p53 protein. Eight mutants, each derived from primary resected tissues of lung carcinomas, were expressed in vitro under strictly defined conditions, such that the only known variant was the point mutation present in each p53 mRNA. All the mutations were located in highly conserved domains. The tertiary structure of each mutant protein was investigated by reactivity with anti-p53 monoclonal antibodies directed against conformation-dependent epitopes. Quaternary structure was examined by gel filtration. Although all the mutant proteins exhibited abnormal tertiary structures, their quaternary structures appeared similar to wild type, the one exception being p53-tyr135, which contains tyrosine in place of cysteine at residue 135. The conformational phenotype of mutant human p53 was found to be dependent upon (i) the locus of the mutation and (ii) the nature of the amino acid substitution: two different substitutions at residue 273 yielded two mutants with differing structural properties. We have discovered three mutants of human p53 that are temperature sensitive for conformation; one is mutated at codon 273, a 'hotspot' for p53 mutation in human cancer.

Mutations in the p53 gene in primary human breast cancers

Twenty-six primary breast tumors were examined for mutations in the p53 tumor suppressor gene by an RNase protection assay and nucleotide sequence analysis of PCR-amplified p53 complementary DNAs. Each method detected p53 mutations in the same three tumors (12%). One tumor contained two mutations in the same allele. Single strand conformation polymorphism analysis of genomic DNA and complementary DNA proved more sensitive in the detection of mutations. Combining this technique with the other two a total of 12 mutations in the p53 gene were demonstrated in 11 tumors (46%), and a polymorphism at codon 213 was detected in another tumor. Loss of heterozygosity on chromosome 17p was detected by Southern blot analysis in 30% of the tumor DNAs. Not all of the tumors containing a point mutation in p53 also had loss of heterozygosity of the remaining allele, suggesting that loss of heterozygosity may represent a later event.

Polymorphism at codon 213 within the p53 gene

This report describes a rare polymorphism at codon 213 (silent alteration of CGA to CGG) within the coding region of the p53 gene. The rare polymorphic allele was present in six cases out of 189 lung and breast cancer DNAs analyzed (3.2%) and resulted in the loss of a TaqI site. This allele could be mistaken for a mutation when screening methods of mutation analysis are used without comparison with normal tissue DNA.

Occurrence of p53 gene abnormalities in gastric carcinoma tumors and cell lines

We explored the state of the p53 gene in gastric cancer. Using one or more methods, we examined 15 specimens from primary carcinomas (14 tumors, one cell line), five cell lines derived from metastases, and seven paired samples of nonmalignant gastric mucosa. Sequence analyses of complementary DNA containing the entire p53 gene open reading frame demonstrated abnormalities in one of five samples from primary tumors and in all five samples from metastases. The single cell line derived from a primary carcinoma had no abnormality of the gene. The six abnormalities included four point mutations, one base-pair deletion resulting in a frame shift, and a 24 base-pair deletion caused by an intronic point mutation (as determined by sequence analysis of genomic DNA). Four of the six mutations mapped to regions highly conserved among species or involved in simian virus 40 T-antigen binding. Restriction fragment length polymorphism studies confirmed that chromosome 17p allelic deletions occur only in a minority of primary tumors, but that they may occur more frequently in metastases. Northern blotting and ribonuclease protection assays detected only a fraction of the p53 gene abnormalities detected by sequencing. Our findings indicate that mutations of the p53 gene are relatively rare in primary gastric tumors but appear to be relatively frequent in cell lines derived from metastatic lesions. Our results may help in understanding the molecular events associated with progression and metastasis in gastric carcinoma.

A chemical mismatch cleavage method useful for the detection of point mutations in the p53 gene in lung cancer

Point mutations in genes can be etiologic of pulmonary diseases, as in the case of the inherited disorders alpha-1-antitrypsin deficiency and cystic fibrosis or in the context of dominant and recessive oncogenes in lung cancer. Various methodologies have been developed to screen for single-base mutations. These techniques include direct DNA sequencing, RNase protection, denaturing gradient gel electrophoresis, and chemical mismatch cleavage. The latter method offers the advantages of rapid and efficient analysis of genomic or cDNA and is thus ideally suited to screening applications. Furthermore, all possible single-base changes can theoretically be detected. In the present work, chemical mismatch cleavage was utilized to detect mutations in the p53 gene in small cell and non-small cell lung cancer. This technique was modified by using a two-step, hemi-nested PCR procedure for preparation of target genomic DNAs permitting an expanded target size for analysis. Evaluation by chemical mismatch cleavage of eight p53 cDNAs derived from lung tumors shown to have different mutations by DNA sequencing correctly detected the presence of a point mutation in all instances. Analysis of six additional tumor genomic DNAs with defined mutations in the corresponding p53 cDNAs accurately confirmed the mutation at the level of the genome. The technique also identified codon 72 and intron 6 polymorphisms. Using the intron 6 polymorphism, loss of heterozygosity at the p53 locus in tumor DNA was readily detected by chemical mismatch cleavage. Finally, utilizing this technique for scanning analysis of the p53 gene of uncharacterized lung tumor DNAs, additional mutations were identified in a prospective manner which were confirmed by sequence analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of intronic point mutations as an alternative mechanism for p53 inactivation in lung cancer

The p53 gene initially was thought to be an oncogene, but recent evidence suggests that wild-type p53 can function as a tumor suppressor gene in lung, colon, and breast cancer as well as less common malignancies. This study reports the first identification of intronic point mutations as a mechanism for inactivation of the p53 tumor suppressor gene. Abnormally sized p53 mRNAs found in a small cell and a non-small cell lung cancer cell line were characterized by sequence analysis of cDNA/PCR products, the RNase protection assay and immunoprecipitation. These mRNAs were found to represent aberrant splicing leading to the production of abnormal or no p53 protein. Sequence analysis of genomic DNA revealed that a point mutation at the splice acceptor site in the third intron or the splice donor site in the seventh intron accounts for the abnormal mRNA splicing. In one patient the same intronic point mutation was found in the tumor cell line derived from a bone marrow metastasis and in multiple liver metastases but not in normal DNA, indicating that it occurred as a somatic event before the development of these metastases. These findings further support the role of inactivation of the p53 gene in the pathogenesis of lung cancer and indicate the role of intronic point mutation in this process.

Regression mechanisms of mouse fibrosarcoma cells after in vitro exposure to quercetin: diminution of tumorigenicity with a corresponding decrease in the production of prostaglandin E2

We have previously reported that both regressor (QR) and progressor (metastatic, QP) clones were obtained after the in vitro exposure of a mouse fibrosarcoma BMT-11 cl-9 to quercetin. In this study, we investigated possible mechanisms of spontaneous regression of QR clones as compared with tumorigenic QP and BMT-11 cl-9 tumor clones. We observed that BMT-11 cl-9 cells produced relatively high amounts of prostaglandin E2 (PGE2) during in vitro culture. The average production by 11 subclones of BMT-11 cl-9 cells was 9236 +/- 2829 pg/ml whereas that by 9 QR clones was 3411 +/- 2213 pg/ml (P less than 0.02). Indomethacin not only inhibited in vitro PGE2 synthesis by QP clones (high-PGE2 producers) but also the s.c. growth of QP clones in mice. Chronological changes in host immune responses to tumor-associated antigen were measured by cytotoxic T lymphocyte (CTL) activity examined after mixed lymphocyte/tumor cell culture of spleen cells obtained from tumor-bearing mice. The CTL activity disappeared abruptly in the spleen of QP-clone-bearing mice 21 days after the inoculation of tumors, whereas the spleen cells of QR-clone-inoculated mice retained their CTL activity. We determined that the mechanism responsible for the regression of these regressor clones is not due to any qualitative or quantitative increase in pre-existing membrane antigens, nor the emergence of new antigen(s) on the cell surface of the QR clones: nor was it due to enhanced susceptibility of QR clones to natural killer cells, lymphokine-activated killer cells and macrophages. These finding suggest that the regression mechanism of QR clones may be the diminished inhibition of host response to tumor-associated antigen caused by the reduced production of PGE2 by QR clones.

p53: a frequent target for genetic abnormalities in lung cancer

Allele loss is a hallmark of chromosome regions harboring recessive oncogenes. Lung cancer frequently demonstrates loss of heterozygosity on 17p. Recent evidence suggests that the p53 gene located on 17p13 has many features of such an antioncogene. The p53 gene was frequently mutated or inactivated in all types of human lung cancer. The genetic abnormalities of p53 include gross changes such as homozygous deletions and abnormally sized messenger RNAs along with a variety of point or small mutations, which map to the p53 open reading frame and change amino acid sequence in a region highly conserved between mouse and man. In addition, very low or absent expression of p53 messenger RNA in lung cancer cell lines compared to normal lung was seen. These findings, coupled with the previous demonstration of 17p allele loss in lung cancer, strongly implicate p53 as an anti-oncogene whose disruption is involved in the pathogenesis of human lung cancer.

Growth-associated shedding of a tumor antigen (CE7) detected by a monoclonal antibody

A monoclonal antibody was developed against an antigen, termed CE7, which was highly expressed on the surface of rat fibrosarcoma KMT-17 cells (clone A3) cultured in low serum medium (A3-1% FCS). The CE7 antigen was not detectable on A3 cells cultured in ordinary high serum medium (A3-10% FCS), on in vivo passaged A3 cells, or on parental in vivo KMT-17 cell line. However, immunoelectron microscopy and Western blot analyses indicated that CE7 antigen was produced by these tumor cells in all circumstances but was shed from their surfaces in vesicular form into the surrounding tissue culture medium or ascites, unless low serum concentration prevailed and disappeared from their cell surfaces. We have previously reported that the immunogenicity of A3 cells was increased when the serum concentration was lowered from 10% to 1% and the phenomenon paralleled the CE7 antigen expression on the A3 cells. These results suggest that the CE7 antigen could be a tumor-associated rejection antigen and that the expression of the CE7 antigen on A3-1% FCS cells (which is shed by high serum culture or in vivo transplantation and disappears from the cell surface) may play a role in immunological responses against the tumor cells.

[Effects of environmental changes around tumor cells on immunogenicity, and its mechanisms]

I studied alterations in the tumorigenicity and immunogenicity of cultured rat fibrosarcoma clone in different growth environments. When the fetal calf serum concentration in a medium was lowered from 10% to 1%, the tumorigenicity was diminished while the immunogenicity was enhanced, accompanied by a prolongation of the in vitro doubling time in a reversible manner. These phenomena were not associated with the quantities of the tumor-associated antigen and/or the rat major histocompatibility complex, but were associated with the appearance of a unique antigen (s), which consist of glycoprotein and exist as a crypt-antigen (s). Our observations indicate that the in vitro growth environment modifies the surface of tumor cells and causes a reduction in their tumorigenicity and an enhancement of their immunogenicity.

Suppression of transformed phenotypes in intraspecific somatic cell hybrid clones between the c-myc activating mouse plasmacytoma line and normal cells

The role of normal-cell-derived chromosome 15 in suppressing transformed phenotypes was studied in intraspecific hybrid clones between the c-myc oncogene activating BALB/c mouse plasmacytoma (S194) cells and normal spleen cells or fibroblasts from CBA/H-T6 mice. All the hybrid clones between S194 and normal spleen cells grew very rapidly in suspension and formed colonies in soft agar. In contrast, the hybrid clones between S194 and normal fibroblasts grew slowly in an attached form. They were divided into 2 groups on the basis of their morphology and growth properties: most clones showed flat type morphology, and no colony formation was seen in soft agar, while some clones grew in a piled-up fashion and formed colonies in soft agar. The hybrid clones between S194 and normal spleen cells lost some normal-cell-derived chromosomes but retained most tumor-derived marker chromosomes including the t(12;15) chromosome which carried the activated c-myc oncogene. On the other hand, hybrid clones between S194 cells and normal fibroblasts retained almost all chromosomes from both parental cells. With respect to retention of normal-cell-derived chromosome 15, both the flat and piled-up type clones retained 2 copies each of the t(14;15) and T6 marker chromosomes, the normal counterparts of the t(12;15) chromosomes. Our results suggest that the transformed phenotypes of the hybrid clones between S194 cells and normal fibroblasts are negatively modulated by normal-cell-derived chromosomes but not by normal-cell-derived chromosome 15 alone.

Enhanced immunogenicity of the cultured rat fibrosarcoma KMT-17 by cultivation in a low concentration of fetal calf serum

We examined in different culture conditions alterations in the tumorigenicity and immunogenicity of an A3 clone that had been derived from a rat fibrosarcoma KMT-17. When a fetal calf serum concentration in a culture medium was lowered from 10 to 1%, the tumorigenicity was diminished while the immunogenicity was enhanced in a reversible manner; this was accompanied by a reversible prolongation of the in vitro doubling time. These phenomena were not due to an increase in the quantities of the original tumor-associated antigen and/or of the rat major histocompatibility complex (RT1) but seemed to be due to the appearance of a unique antigen(s) that was detected by an antibody taken from rats immunized with A3 tumor cells cultured in the low fetal calf serum concentration; this antigen(s) may consist of glycoprotein and exist as a crypt antigen(s). These phenomena were measured by an absorption test and flow cytometric analysis. Our observations suggest that the in vitro culture condition of tumor cells, in particular their culturing in the low fetal calf serum concentration medium, modifies the surface of tumor cells and causes a diminishment in their tumorigenicity and an enhancement of their immunogenicity.

Unresponsiveness of both non-rearranged and rearranged c-myc to serum stimulation in a mouse plasmacytoma S194

Expression of non-rearranged and rearranged c-myc in a mouse plasmacytoma cell line S194 cultured in different serum concentration or temperature was examined. Exponentially growing S194 cells expressed a high level of rearranged c-myc and a low level of non-rearranged c-myc mRNAs. The levels of the two c-myc mRNAs were nearly the same in the cells in which growth was suppressed by lowering serum concentrations or incubation temperature in culture medium. Furthermore, even when serum-deprived S194 cells resumed growth following serum restimulation, the induction of non-rearranged c-myc mRNA, observed in a mouse T-cell lymphoma cell line BW5147, was not demonstrated. In contrast to the unchanged c-myc expression, the level of N-ras mRNA was related to changes in cell growth rate induced by changes in serum concentration in S194 cells. These results suggest that not only the rearranged c-myc but also the non-rearranged c-myc is unresponsive to serum stimulation and temperature changes, even though cell growth rate is markedly changed.

Development of highly immunogenic variants of a rat fibrosarcoma line during in vitro cultivation

Rat fibrosarcoma KMT-17 cells decreased in tumorigenicity when cultured in vitro. Eight clones derived from cultured KMT-17 cell lines (c-KMT-17) were examined for their tumorigenicity, immunosensitivity, and immunogenicity. All the clones were less or nontumorigenic in normal syngeneic rats than KMT-17 cells maintained in vivo. All eight clones produced tumors in rats immunosuppressed with 600 rad 60Co; differences in degree of tumorigenicity were seen among clones in rats irradiated with 250 rad 60Co. Although immunosensitivity of the eight clones to complement-dependent and cell-mediated cytotoxicity was the same or less than that of KMT-17 cells, al leight clones induced greater transplantation resistance to KMT-17 than KMT-17 itself. Cold target inhibition tests demonstrated new antigens in a highly immunogenic variant in addition to the original tumor associated antigen (TAA). New glycolipids, not observed in KMT-17 cells, were demonstrated in the clones by thin layer chromatography. These results suggest that new antigens appearing during culture of KMT-17 may act as helper antigens for TAA, increasing the immunogenicity and decreasing the tumorigenicity of the cultured cells.