Looking in the mouth for noninvasive gene expression-based methods to detect oral, oropharyngeal, and systemic cancer

Comparing Two Methods for the Isolation of Exosomes

Exosomes are membrane-bound nanovesicles released by cells into their extracellular environment. They carry different types of RNA including mRNA which may be useful in the diagnosis of various diseases. Exosome isolation has been a challenge because of their small size; therefore, two exosome isolation methods were compared in this study. The Exoquick-TC PLUS™ exosome isolation kit (kit) was compared with the classic ultracentrifugation (UC) method for exosome isolation. In samples obtained using both methods, cryo-electron microscopy showed round or slightly elongated vesicles with diameters ranging from 50 to 150 nm and delimited by a bilayered membrane. Dynamic light scattering resulted in multiple peaks for kit exosomes, whereas a single peak was observed for UC exosomes. Significantly, more total RNA was present in UC exosomes in contrast to kit exosomes (P < 0.0001). This was reflected in subsequent mRNA analysis using qPCR, where UC exosomes had lower Ct values compared to kit exosomes. In conclusion, exosome characterization revealed the presence of exosomes in both UC and the kit samples. The kit samples presented additional peaks from DLS which might be due to impurities. Overall, due to a higher total RNA and mRNA content, UC is a better option for subsequent mRNA analysis; nevertheless, the kit can still be used if an ultracentrifuge is not available as four out of the five genes selected were detected and quantified using the kit.

Analysis of primary oral and oropharyngeal squamous cell carcinoma in inhabitants of Beijing, China-a 10-year continuous single-center study

Background

This study aimed to describe some of the characteristics of the inhabitants of Beijing with oral and oropharyngeal squamous cell carcinoma (OSCC) who had received treatment at the Stomatology Hospital of Peking University and to analyze the survival rate and the prognostic factors of patients following surgical treatment.

Methods

Data for 603 consecutive cases with primary OSCC between 2004 and 2013 were obtained from the Stomatology Hospital of Peking University. Clinical data including age, sex, living district, primary tumor site, TNM stage, history of drinking and smoking, pathological differentiation, treatment, and survival were retrospectively analyzed.

Results

The male:female ratio was 1.1:1. The frequency of site involvement in descending order was tongue (34.3%), gingiva (25.0%), buccal mucosa (13.8%), oral floor (9.0%), oropharynx (8.5%), lip (6.3%) and palate (3.2%). Female OSCC patients tended to be significantly older than men with OSCC (P < 0.05). The percentage of patients with TNM stage III–IV OSCC was 52.4%. The results revealed that 65.3% of male patients and only 6.3% of female patients smoked or drank. The overall 5-year survival rate was 64%. Female patients had a worse prognosis than male patients. Among the patients who received surgery, tumor size and lymph node involvement were independent prognostic factors. Smoking and drinking were not prognostic factors.

Conclusion

Among the Beijing inhabitants who were diagnosed with OSCC and treated in our hospital in the past 10 years, more than half were in the advanced stage, and the cancer stage was the main prognostic factor of oral cancer. Therefore, the recognition of oral cancer should be strengthened, and early detection and treatment of OSCC should be achieved to improve the survival rate.

Salivary MMP-9 in the detection of oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) is the most common malignant tumour of the oral cavity. Detection of OSCC is currently based on clinical oral examination combined with histopathological evaluation of a biopsy sample. Direct contact between saliva and the oral cancer makes measurement of salivary metalloproteinase- 9 (MMP-9) an attractive alternative.

Material and Methods

In total, 30 OSCC patients and 30 healthy controls were included in this prospective study. Saliva samples from both groups were collected, centrifuged and supernatant fluid was subjected to ELISA for assessment of MMP-9. The median salivary MMP-9 values with interquartile range (IQR) of OSCC patients and the control group were statistically analysed using the Mann-Whitney U-test. The receiver operating characteristic (ROC) curve was constructed and the area under curve (AUC) was computed.

Results

The median absorbance MMP-9 value of the OSCC group was 0.186 (IQR=0.158) and that of control group was 0.156 (IQR=0.102). MMP-9 was significantly increased in the OSCC patients than in the controls by +19.2% (p=0.008). Median values in patients with recurrence and in patients with primary event were 0.233 (IQR=0.299) and 0.186 (IQR=0.134) respectively. MMP-9 was significantly increased in patients with primary event (p=0.017) compared to controls by +19.2%. No significant increase of MMP-9 level was detected when comparing patients with recurrence and healthy controls (+49.4%; p=0.074). The sensitivity value of MMP-9 was 100% whereas the specificity value was 26.7% with AUC of 0.698.

Conclusions

The present data indicates that the elevation of salivary levels of MMP-9 may be a useful adjunctive diagnostic tool for detection of OSCC. However, further studies are necessary to provide scientific and clinical validation.

Key words:Oral squamous cell carcinoma, oral cancer, saliva, salivary diagnostics, cancer detection, MMP-9, metalloproteinases.

Improving accuracy of RNA-based diagnosis and prognosis of oral cancer by using noninvasive methods

RNA-based diagnosis and prognosis of squamous cell carcinoma has been slow to come to the clinic. Improvements in RNA measurement, statistical evaluation, and sample preservation, along with increased sample numbers, have not made these methods reproducible enough to be used clinically. We propose that, in the case of squamous cell carcinoma of the oral cavity, a chief source of variability is sample dissection, which leads to variable amounts of stroma mixed in with tumor epithelium. This heterogeneity of the samples, which requires great care to avoid, makes it difficult to see changes in RNA levels specific to tumor cells. An evaluation of the data suggests that, paradoxically, brush biopsy samples of oral lesions may provide a more reproducible method than surgical acquisition of samples for miRNA measurement. The evidence also indicates that body fluid samples can show similar changes in miRNAs with oral squamous cell carcinoma (OSCC) as those seen in tumor brush biopsy samples - suggesting much of the miRNA in these samples is coming from the same source: tumor epithelium. We conclude that brush biopsy or body fluid samples may be superior to surgical samples in allowing miRNA-based diagnosis and prognosis of OSCC in that they feature a rapid method to obtain homogeneous tumor cells and/or RNA.

A loss of profilin-1 in late-stage oral squamous cell carcinoma

BACKGROUND

The genes for PFN1 and TMSB4 are both highly expressed in oral tissue and both encode actin monomer binding proteins thought to play a role in cell motility and possibly other crucial parts of tumor progression.

METHODS

Oral brush cytology of epithelium from oral squamous cell carcinoma (OSCC) was used to measure PFN1 and TMSB4 mRNA in OSCC, while immunohistochemical analysis of tissue was used to check protein levels.

RESULTS

High but variable expression of mRNAs encoding these two proteins was observed suggesting they may contribute to tumor characteristics in a subset of OSCCs. Both proteins were highly expressed in normal appearing basal epithelium, in the cytoplasm, and perinuclear area, while expression was minimal in upper epithelial layers. In OSCCs, expression of these proteins varied. In tumors classified as later stage, based on size and/or lymph node involvement, PFN1 levels were lower in tumor epithelium. A control gene, KRT13, showed expression in normal differentiated basal and suprabasal oral mucosa epithelial cells and as reported was lost in OSCC cells.

CONCLUSION

Loss of PFN1 in tumor cells has been associated with lymph node invasion and metastasis in other tumor types, strengthening the argument that the protein has the potential to be a tumor suppressor in late-stage OSCC.

microRNA from brush biopsy to characterize oral squamous cell carcinoma epithelium

Few cancers are diagnosed based on RNA expression signatures. Oral squamous cell carcinoma (OSCC) is no exception; it is currently diagnosed by scalpel biopsy followed by histopathology. This study sought to identify oral tumor epithelial microRNA (miRNA) expression changes to determine if these changes could be used to diagnose the disease noninvasively. Analysis of miRNA profiles from surgically obtained OSCC tissue, collected under highly standardized conditions for The Cancer Genome Atlas, was done to determine the potential accuracy in differentiating tumor from normal mucosal tissue. Even when using small 20 subject datasets, classification based on miRNA was 90 to 100% accurate. To develop a noninvasive classifier for OSSC, analysis of brush biopsy miRNA was done and showed 87% accuracy in differentiating tumor from normal epithelium when using RT‐qPCR or miRNAseq to measure miRNAs. An extensive overlap was seen in differentially expressed miRNAs in oral squamous cell carcinoma epithelium obtained using brush biopsy and those reported in saliva and serum of oral squamous cell carcinoma patients in several studies. This suggested that nonselective release of these miRNAs into body fluids from tumor epithelium was largely responsible for the changes in levels in these fluids seen with this disease. Using a variation in mirRPath we identified the KEGG pathway of neurotrophin signaling as a target of these miRNAs disregulated in tumor epithelium. This highlights the utility of brush biopsy of oral mucosa to allow simple acquisition of cancer relevant miRNA information from tumor epithelium.

miR-98 suppresses tumor cell growth and metastasis by targeting IGF1R in oral squamous cell carcinoma

Increasing evidences indicate that dysregulation of miRNAs contributes to the pathogenesis of oral squamous cell carcinoma (OSCC). However, little is known about the potential role of miR-98 in OSCC. Here, we found that miR-98 was downregulated in OSCC tissues and cell lines. Overexpression of miR-98 inhibited proliferation, colony formation, migration, and invasion of OSCC cells. IGF1R was identified as the potential target of miR-98 using dual luciferase assay, qRT-PCR and western blot. Furthermore, restoration of IGF1R remarkably reversed the tumor-suppressive effects of miR-98 on OSCC cells. Moreover, miR-98 expression was inversely correlated with IGF1R expression in 19 cases of OSCC. These findings suggest that miR-98 inhibits cancer cell growth and metastasis by direct targeting IGF1R, implicating miR-98 as a novel potential therapeutic target for OSCC.

Oral cancer incidence and mortality in China, 2011

OBJECTIVE

To descript the incidence and mortality rates of oral cancer among Chinese population in 2011, and provide valuable data for oral cancer prevention and research.

METHODS

Data from 177 population-based cancer registries distributed in 28 provinces were accepted for this study after evaluation based on quality control criteria, covering a total of 175,310,169 populations and accounting for 13.01% of the overall national population in 2011. Incidence and mortality rates were calculated by area, gender and age groups. The numbers of new cases and deaths were estimated using the 5-year age-specific cancer incidence/mortality rates and the corresponding populations. The Chinese population in 2000 and World Segi's population were used for age-standardized rates.

RESULTS

The estimate of new cases diagnosed with oral cancer was 39,450 including 26,160 males and 13,290 females. The overall crude incidence rate for oral cancer was 2.93/100,000. The age-standardized rates by China (ASRCN) population and by World population (ASRwld) were 2.22/100,000 and 2.17/100,000, respectively. Among subjects aged 0-74 years, the cumulative incidence rate was 0.25%. The estimated number of oral cancer deaths of China in 2011 was 16,933, including 11,794 males and 5,139 females. The overall crude mortality rate was 1.26/100,000, accounting for 0.80% of all cancer deaths. The ASRCN and ASRwld for mortality were 0.90/100,000 and 0.89/100,000, respectively. Among subjects aged 0-74 years, the cumulative mortality rate was 0.10%. The incidence and mortality rates of oral cancer were much higher in males and urban areas than in females and rural areas. In addition, the incidence and mortality rates were increased by the raising of ages.

CONCLUSIONS

Results in the study may have important roles for oral cancer prevention and research. Although oral cancer burden of China is not high, we must pay attention to this malignancy as well. In addition, further researches need to be done for primary and secondary prevention research of oral cancer, especially for the high risk population.

The use of information theory in evolutionary biology

Information is a key concept in evolutionary biology. Information stored in a biological organism's genome is used to generate the organism and to maintain and control it. Information is also that which evolves. When a population adapts to a local environment, information about this environment is fixed in a representative genome. However, when an environment changes, information can be lost. At the same time, information is processed by animal brains to survive in complex environments, and the capacity for information processing also evolves. Here, I review applications of information theory to the evolution of proteins and to the evolution of information processing in simulated agents that adapt to perform a complex task.