Oral hypofunction is a new concept that addresses the oral function of older adults. Few studies have investigated the relationship between oral hypofunction and general health conditions such as frailty, sarcopenia, and mild cognitive impairment. This paper explores these relationships in a large-scale, cross-sectional cohort study. The relationships of oral hypofunction with frailty, sarcopenia, and mild cognitive impairment were examined using data from 832 individuals who participated in the 2018 health survey of the residents of Tarumizu City, Kagoshima Prefecture, Japan. Individuals with frailty, sarcopenia, and mild cognitive impairment had significantly higher rates of oral hypofunction. Frailty was independently associated with deterioration of the swallowing function (odds ratio 2.56; 95% confidence interval, 1.26–5.20), and mild cognitive impairment was independently associated with reduced occlusal force (odds ratio 1.48; 95% confidence interval, 1.05–2.08) and decreased tongue pressure (odds ratio 1.77; 95% confidence interval, 1.28–2.43). There was no independent association found between sarcopenia and oral function. In conclusion, early intervention for related factors such as deterioration of the swallowing function in frailty, reduced occlusal force, and decreased tongue pressure in mild cognitive impairment could lead to the prevention of general hypofunction in older adults.

Oral microbiota is reportedly associated with gut microbiota and influences colorectal cancer (CRC) progression; however, the details remain unclear. This study aimed to evaluate the role of oral microbiota in CRC progression. Fifty-two patients with CRC and 51 healthy controls were included. Saliva and stool samples were collected, and microbiota were evaluated using 16S rRNA analysis and next-generation sequencing. Comparative analysis was performed on both groups. Linear discriminant analysis effect size (LEfSe) revealed the presence of indigenous oral bacteria, such as Peptostreptococcus, Streptococcus, and Solobacterium spp., at a significantly higher relative abundance in saliva and stool samples of CRC patients compared with controls. Next, CRC patients were divided into early stage (Stage I, II; n = 26; 50%) and advanced stage (Stage III, IV; n = 26; 50%) disease. LEfSe revealed that S. moorei was present at a significantly higher relative abundance in the advanced-stage group compared with the early-stage group, again consistent for both saliva and stool samples. Among bacterial species with significantly higher relative abundance in CRC patients, P. stomatis, S. anginosus, S. koreensis, and S. moorei originated from the oral cavity, suggesting indigenous oral bacteria may have promoted initiation of CRC carcinogenesis. Furthermore, S. moorei may influence CRC progression.

We previously showed that ΔNp63β, a splicing variant of ΔNp63, mediated EMT and affected cell motility. DNA microarray was thus performed to elucidate the mechanism that ΔNp63β affects cell motility. As the results, Wnt5a was significantly down-regulated by ΔNp63β overexpression in tongue SCC cell line (SQUU-B) with EMT phenotype. Seven OSCC cell lines were used. Expression of ΔNp63, Wnt5a, its receptor Ror2, and matrix metalloproteinases (MMPs) were analyzed by RT-PCR, real-time PCR, and western blotting, and gelatin zymography. Furthermore, we examined the effects of siRNA for Wnt5a or Ror2 and recombinant human Wnt5a (rhWnt5a) on motility of tongue SCC cells. Biopsy specimens from tongue SCC patients were used for immunohistochemical staining of Wnt5a and Ror2. Wnt5a and Ror2 were expressed only in SQUU-B cells without ΔNp63 expression, and negatively associated with ΔNp63 expression in other cells. ΔNp63β overexpression in SQUU-B cells decreased Wnt5a and Ror2 expression. By Wnt5a or Ror2 knockdown, cell motility was remarkably inhibited, but EMT markers expression was unaffected. MMP-2 expression and the activities inversely correlated with ΔNp63 expression, and were inhibited by Wnt5a or Ror2 knockdown. Cell motility and MMP-2 activities were recovered by adding rhWnt5a in the cells with Wnt5a knockdown, but not in those with Ror2 knockdown. Moreover, immunohistochemical analyses in tongue SCC specimens found that high expression of Wnt5a or Ror2 was associated with poorer prognosis. Wnt5a-Ror2 signaling enhanced tongue SCC cell aggressiveness and promoted production of MMP-2 following ΔNp63β-mediated EMT.

Few studies have investigated the relationship between nutritional status and comprehensive assessment of oral hypofunction, especially protein intake-related sarcopenia. Thus, we explored these relationships in a large-scale cross-sectional cohort study using the seven-item evaluation for oral hypofunction and Diet History Questionnaire for nutritional assessment. We used the data from 1004 individuals who participated in the 2019 health survey of the residents of Tarumizu City, Kagoshima Prefecture, Japan for analysis. We found that individuals with oral hypofunction were significantly older with a lower skeletal muscle index. Although there were few foods that had a significant difference between the groups with and without oral hypofunction, the consumption of beans and meats was significantly lower in women and men in the oral hypofunction group, respectively. According to the lower limit of the tentative dietary goal defined in Japan, comprehensive evaluation of oral hypofunction was significantly and independently associated with protein intake in both men and women (odds ratio, 1.70; 95% confidence interval, 1.21–2.35). In conclusion, we found that oral hypofunction was associated with targeted protein intake for sarcopenia and frailty prevention in middle-aged and older community-dwelling adults. Comprehensive evaluation of oral function with intervention in cases of hypofunction could inform clinicians to better prevent sarcopenia.

We previously reported that epithelial-to-mesenchymal transition (EMT) was mediated by ΔNp63β in oral squamous cell carcinoma (OSCC). In this study, DNA microarray analyses were performed using ΔNp63β-overexpressing OSCC cells to identify genes associated with ΔNp63β-mediated EMT. Thereby, we focused on kallikrein-related peptidase (KLK) 6, most up-regulated following ΔNp63β-overexpression, that activates protease-activated receptors (PARs). In RT-PCR analyses, ΔNp63 was positively associated with KLK6 and PAR2 and negatively with PAR1 in OSCC cells. By ΔNp63 knockdown, KLK6 and PAR2 expression was decreased and PAR1 was increased. Furthermore, KLK6 knockdown led to enhancing migration and invasion, and inhibiting proliferation, suggesting EMT-phenotypes. Although, in the KLK6 or PAR2 knockdown cells, phosphorylation of ERK was reduced, it was restored in the KLK6 knockdown OSCC cells treated with recombinant KLK6 proteins. Immunohistochemistry showed ΔNp63, KLK6, and PAR2 were more strongly expressed in the epithelial dysplasia and central region of OSCC than normal oral epithelium, whereas PAR1 expression was undetectable. Interestingly, at the invasive front of OSCC, ΔNp63, KLK6, and PAR2 were reduced, but PAR1 was elevated. In addition, the OSCC patients with decreasing KLK6 expression at the invasive front had more unfavourable prognosis. These results suggested differential roles of KLK6 in malignant transformation and EMT; high ΔNp63β expression up-regulates KLK6-PAR2 and down-regulates PAR1, inducing malignant transformation in oral epithelium with stimulating proliferation through ERK signal activation. Moreover, KLK6-PAR2 expression is down-regulated and PAR1 is up-regulated when ΔNp63β expression is decreased, leading to EMT with enhancing migration and invasion through ERK signal reduction at the invasive front.

Clinically, early-stage oral cancers are difficult to distinguish from oral potentially malignant disorders (OPMDs), and invasive tissue biopsy should be performed to determine a treatment strategy. Previously, we focused on gargle fluid as a noninvasive testing method and reported aberrant methylation in gargle fluid in patients with oral cancer. This study aimed to distinguish early-stage oral cancer from clinically diagnosed OPMDs using gargle fluid samples. We collected gargle fluid samples from 40 patients who were clinically diagnosed with OPMDs in the training set; among them, 9 patients were pathologically diagnosed with oral cancer. Methylation levels of 25 tumor suppressor genes were analyzed using the methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) method. We found that a combination of six genes (TP73, CASP8, RARB, KLLN, GSTP1, and CHFR) could distinguish oral cancer from clinically diagnosed OPMDs with high diagnostic performance (area under the curve [AUC], 0.885; sensitivity, 77.8%; and specificity, 87.1%). Additionally, the panel comprised of the six methylated genes was validated in the test set. Furthermore, when compared with cytology testing, the panel could accurately detect oral cancer. The present methylated gene panel may serve as a novel biomarker for oral cancer.