Cytokeratin expression in squamous cell carcinoma of the lung and oral cavity: an immunohistochemical study with possible clinical relevance

p53, Cytokeratin 19 Expression in Oral Squamous Cell Carcinoma and Correlation with Histopathologic Grading: An Immunohistochemical Study

The purpose of this study was to examine the immunohistochemical expression of p53 and cytokeratin 19 (CK19) in normal oral mucosa (NOM) and oral squamous cell carcinoma (OSCC) and their association with histopathological differentiation grade. The secondary goal was to see if there was any correlation between p53 and CK19 expression in NOM and OSCC. A hospital-based retrospective analysis was conducted in which 40 NOM and 45 OSCC samples were acquired from archives and stained with mouse monoclonal antibodies p53 and CK19. For both the NOM and OSCC groups, the proportion of positively stained cells, staining intensity, and staining index were calculated. p53 immunoexpression revealed that 85% of positively stained cells in the NOM basal layer had a low staining index (mean ± SD 1.87 ± 0.34), whereas 66.7% of positively stained cells in the OSCC had a high staining index (mean ± SD 5.63 ± 3.02). When NOM and OSCC were compared, there was a statistically significant difference in staining intensity. However, despite a linear increase in the percentage of positive cells from well to poorly differentiated, the comparison between histopathological grades was non-significant. CK19 exhibited 18.5% positively stained cells in the NOM basal layer with a low staining index (mean ± SD 1.57 ± 0.53), whereas OSCC samples showed 4.44% immunopositivity with a high staining index. p53 is a marker of oral carcinogenesis independent of histological grade and CK19 expression. Further, CK19 is a marker of dysfunctional epithelial differentiation but lacks sensitivity and specificity; however, it demands further multicentric studies with a large sample size to draw definitive conclusions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-04092-7.

Biochemical analysis of cytokeratin fragment 21-1 concentration and expression of cytokeratin 19 in oral potentially malignant disorders

Introduction

Cytokeratin fragment 21-1 (CYFRA21-1), a constituent of the intermediate filament protein is known to be elevated in cancer. In vitro cleavage of cytokeratin 19 (CK19) protein results in the release of it's fragments into the supernatants of premalignant cell lines. This study was designed with the aim to investigate the concentrations of CYFRA21-1 in serum and saliva of oral potentially malignant disorders (OPMD), to evaluate CK19 expression in tissues of the same patients and to correlate the levels of CYFRA21-1 concentration in serum and saliva with CK19 expression in OPMDs, and to compare it with oral squamous cell carcinoma (OSCC), which was taken as positive control.

Materials and Methods

Concentration of CYFRA21-1 was measured in saliva and serum of 30 OPMD cases with five patients having OSCC using ELISA technique and analysis of CK19 protein expression in the tissue of same patients using immunohistochemical technique was done.

Results

Concentration of CYFRA21-1 in saliva and serum with regard to CK19 protein expression in tissues was significantly higher in control group than in study groups.

Conclusion

CYFRA21-1 can be used as a promising diagnostic molecule and as an adjunctive marker for early detection, disease staging, and monitoring.

A novel miR-365-3p/EHF/keratin 16 axis promotes oral squamous cell carcinoma metastasis, cancer stemness and drug resistance via enhancing β5-integrin/c-met signaling pathway

Background

Targeting the c-Met signaling pathway has become a therapeutic strategy in multiple types of cancer. We unveiled a novel c-Met regulating mechanism that could be applied as a modality for oral squamous cell carcinoma (OSCC) therapy.

Methods

Upregulation of keratin 16 (KRT16) was found by comparing isogenic pairs of low and high invasive human OSCC lines via microarray analysis. OSCC cells with ectopic expression or silencing of KRT16 were used to scrutinize functional roles and associated molecular mechanisms.

Results

We observed that high KRT16 expression significantly correlated with poorer pathological differentiation, advanced stages, increased lymph nodes metastasis, and decreased survival rate from several Taiwanese OSCC patient cohorts. We further revealed that miR-365-3p could target ETS homologous factor (EHF), a KRT16 transcription factor, to decrease migration, invasion, metastasis and chemoresistance in OSCC cells via inhibition of KRT16. Under confocal microscopic examination, c-Met was found possibly partially associates with KRT16 through β5-integrin. Colocalization of these three proteins may facilitate c-Met and β5-integrin–mediated signaling in OSCC cells. Depletion of KRT16 led to increased protein degradation of β5-integrin and c-Met through a lysosomal pathway leading to inhibition of their downstream Src/STAT3/FAK/ERK signaling in OSCC cells. Knockdown of KRT16 enhanced chemosensitivity of OSCC towards 5-fluorouracil (5-FU). Various combination of c-Met inhibitor (foretinib), protein tyrosine kinase inhibitor (genistein), β5-integrin antibody, and 5-FU markedly augmented cytotoxic effects in OSCC cells as well as tumor killing effects in vitro and in vivo.

Conclusions

Our data indicate that targeting a novel miR-365-3p/EHF/KRT16/β5-integrin/c-Met signaling pathway could improve treatment efficacy in OSCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1091-5) contains supplementary material, which is available to authorized users.

Immunohistochemical quantification of expression of a tight junction protein, claudin-7, in human lung cancer samples using digital image analysis method

BACKGROUND AND OBJECTIVES

Tight junction proteins are correlated with cancer development. As the pivotal proteins in epithelial cells, altered expression and distribution of different claudins have been reported in a wide variety of human malignancies. We have previously reported that claudin-7 was strongly expressed in benign bronchial epithelial cells at the cell-cell junction while expression of claudin-7 was either altered with discontinued weak expression or completely absent in lung cancers. Based on these results, we continued working on the expression pattern of claudin-7 and its relationship with lung cancer development. We herein proposed a new Digital Image Classification, Fragmentation index, Morphological analysis (DICFM) method for differentiating the normal lung tissues and lung cancer tissues based on the claudin-7 immunohistochemical staining.

METHODS

Seventy-seven lung cancer samples were obtained from the Second Affiliated Hospital of Zhejiang University and claudin-7 immunohistochemical staining was performed. Based on C++ and Open Source Computer Vision Library (OpenCV, version 2.4.4), the DICFM processing module was developed. Intensity and fragmentation of claudin-7 expression, as well as the morphological parameters of nuclei were calculated. Evaluation of results was performed using Receiver Operator Characteristic (ROC) analysis.

RESULTS

Agreement between these computational results and the results obtained by two pathologists was demonstrated. The intensity of claudin-7 expression was significantly decreased while the fragmentation was significantly increased in the lung cancer tissues compared to the normal lung tissues and the intensity was strongly positively associated with the differentiation of lung cancer cells. Moreover, the perimeters of the nuclei of lung cancer cells were significantly greater than that of the normal lung cells, while the parameters of area and circularity revealed no statistical significance.

CONCLUSIONS

Taken together, our DICFM approach may be applied as an appropriate approach to quantify the immunohistochemical staining of claudin-7 on the cell membrane and claudin-7 may serve as a marker for identification of lung cancer.

Cytokeratin 17 mRNA as a prognostic marker of oral squamous cell carcinoma

Despite diagnostic and therapeutic advances, the 5-year survival rate of oral squamous cell carcinoma (OSCC) remains between 70–80% due to recurrences and secondary metastases to cervical lymph nodes. It is difficult to find these recurrences and metastases postoperatively, thus, careful follow-up is recommended. Cytokeratins (CKs) are intermediate filaments of the cytoskeleton and candidate prognostic biomarkers for OSCC, as they are overexpressed in OSCC compared with normal mucosa. The aim of the present study was to determine the relative levels of occurrence of 3 CK mRNA (CK17, CK19, CK20) transcripts in peripheral blood mononuclear cells (PBMC) using reverse transcription-quantitative polymerase chain reaction. The study comprised pre- and post-operative PBMC samples from 19 OSCC patients. In the good-prognosis group, 10 of 13 patients demonstrated reduced CK17 mRNA expression post-operatively, compared with pre-operative samples, conversely, only 3 of 6 patients in the poor-prognosis group had reduced post-operative CK17 mRNA expression. This difference was statistically significant (P<0.01). The disease-free survival rate of the group with reduced post-operative CK17 mRNA expression was significantly increased compared with the elevated CK17 mRNA group (P<0.01); however, the overall survival rates of the two groups were not significantly different. Neither CK19 mRNA nor CK20 mRNA were significantly expressed in the PBMC of OSCC patients. Overall, CK17 mRNA expression may be a useful prognostic biomarker for OSCC.

CYFRA 21-1 in urine: a diagnostic marker for endometriosis?

Diagnostic workup of endometriosis usually involves laparoscopic inspection and histological examination of biopsies. Unequivocal laboratory parameters for this ailment have not been available in routine diagnostic evaluations thus far. In this study, we examined urine concentrations of cytokeratin 19 (CYFRA 21-1), a structural protein specific for epithelia. We performed immunoassays for CYFRA 21-1 in urine samples from women afflicted with endometriosis throughout their menstrual cycle. We observed a significant increase in CYFRA 21-1 concentrations, corrected by creatinine levels, in the late follicular phase as compared with the level in healthy controls. We conclude that cyclically increased CYFRA 21-1 concentrations in urine could serve as a valuable noninvasive diagnostic parameter in the workup of clinically manifesting endometriosis.

Increased Cyfra 21-1 concentration in saliva from primary oral squamous cell carcinoma patients

BACKGROUND

Saliva is the body fluid in the oral cavity and contacts directly with oral mucosa. As a detective media, it is acceptable and non-traumatic. Cyfra 21-1, being the soluble fragment of cytokeratin 19(CK19), correlates well with oral squamous cell carcinoma (OSCC).

OBJECTIVE

To investigate the saliva Cyfra 21-1 concentrations in OSCC patients and healthy persons, and the correlation between the Cyfra 21-1 concentration in saliva and the CK19 expression in tissue from OSCC patients.

DESIGN

Saliva Cyfra 21-1 concentration was detected by ELISA in 30 OSCC patients and 30 healthy persons; CK19 protein expression and CK19 mRNA level were, respectively, detected by immunohistochemistry and fluorescent real-time RT-PCR in cancerous and paracancerous tissues from 33 OSCC patients.

RESULTS

Saliva Cyfra 21-1 concentration in OSCC patients (85.95+/-78.00 microg/L) was significantly higher than that in healthy persons (42.27+/-40.84 microg/L) (P=0.009); it was also significantly higher in the patients suffering later tumour recurrence (130.95+/-66.38 microg/L) than that in the patients without tumour recurrence (74.84+/-63.45 microg/L) (P=0.023). CK19 protein expression increased significantly in OSCC tissues (P<0.001) with positive rate of 90.9%, CK19 mRNA level in cancerous tissues was 2.21 folds higher than that in paracancerous tissues (P=0.020); significant correlation was found between tissue CK19 protein expression and tissue CK19 mRNA level (P=0.003), and great correlation was found between tissue CK19 protein expression and saliva Cyfra 21-1 concentration (P=0.051).

CONCLUSIONS

The increased CK19 expression in OSCC tissues plays an important role in the increase of saliva Cyfra 21-1 concentration. Potential clinical value of saliva Cyfra 21-1 detection is suggested for OSCC. Further studies are encouraged to reveal the real diagnostic and prognostic value of detecting saliva Cyfra 21-1 concentration for OSCC.

Cytokeratin 17 mRNA expression has potential for diagnostic marker of oral squamous cell carcinoma

PURPOSE

Determination of marker for identification of oral squamous cell carcinoma (OSCC) is important for early diagnosis and individual therapy. Cytokeratins (CKs) like CK 19 and CK 20 are known to be useful diagnostic and prognostic markers for solid tumors. The aim of this study was to evaluate the relevance of further CKs for diagnosis of OSCC.

MATERIALS

In 10 OSCC and 5 normal mucosal samples, the expression patterns of 31 CK genes were examined by cDNA microarray in order to identify CKs with most pronounced over-expression. The results were verified for CK 17, CK 19, and CK 20 in addition to 46 OSCC samples by relative quantification (RQ) using SYBR green real-time reverse transcriptase polymerase chain reaction (RT qPCR). A correlation of the CK expressions with the tumor classification was carried out.

RESULTS

cDNA microarray analyses showed that out of all CKs, CK 17 was up-regulated strongest in OSCC compared to normal samples, and over-expression was most significantly associated with diagnosis (P = 0.002). Expression rates of CK 19 and CK 20 were not significantly different between OSCC samples and normal samples. In 56 samples analyzed by real-time RT qPCR, CK 17 was over-expressed in 53 (94.6%), CK 19 in 18 (32.1%), and CK 20 in 7 (12.5%). The over-expression of CK 17 was significantly associated with metastases of neck lymph nodes (P < 0.05). CK 19 was significantly over-expressed in T3 and T4 OSCC, in stage III and IV patients (P < 0.05), and in poorly differentiated OSCC (P < 0.03). The over-expression of CK 20 was significantly associated with metastases of neck lymph nodes (P < 0.03). Determined by RQ, the mean value of CK 17 over-expression was significantly higher than that of the other CKs (P < 0.01), and was significantly associated with T1 and T2 OSCC (P < 0.03) and with stage I and II patients (P < 0.01).

CONCLUSION

CK 19 might be linked to the clinical progression and differentiation of OSCC, and CK 20 could be associated with metastases of neck lymph nodes in OSCC. Due to the significant up-regulation and the strong over-expression, CK 17 might be the most suitable marker for diagnosis of OSCC out of the CK-family.

Increased CK19 expression correlated with pathologic differentiation grade and prognosis in oral squamous cell carcinoma patients

OBJECTIVE

To investigate cytokeratin 19 (CK19) expression in oral squamous cell carcinoma (OSCC) tissue as well as its correlation with pathologic differentiation grade and prognosis.

STUDY DESIGN

Cancerous and distant tissues from 33 primary OSCC patients were collected during surgery. Each sample was divided into 2 parts, one for CK19 protein detection using immunohistochemistry, and the other for CK19 mRNA-level detection of relative quantification using fluorescent real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

The CK19 positive rate in cancerous tissue was 90.9% (30 out of 33) detected using immunohistochemistry, which was significantly higher than that in distant tissue (15.2%, 5 out of 33) by chi-square test (P < .001). The CK19 positive score in cancerous tissue was also significantly higher than that in the corresponding distant tissue by paired samples t test (P < .001). Patients with positive CK19 expression in distant tissue had higher tumor recurrence rate (P = .008) and lower survival rate (P = .015) than those with negative CK19 expression in distant tissue. Using fluorescent real-time RT-PCR, CK19 mRNA level in cancerous tissue was 2.21-fold higher than that in distant tissue (P = .020). The CK19 expression correlated significantly with pathologic differentiation grade, which was detected not only using immunohistochemistry (P = .002) but also using fluorescent real-time RT-PCR (P = .025), poorer differentiated indicating higher CK19 positive score and CK19 mRNA level.

CONCLUSIONS

Increased CK19 protein expression and gene transcription in OSCC tissue correlate significantly with pathologic differentiation grade. Positive CK19 expression in distant tissue suggests a higher tumor recurrence rate and a lower survival rate.

Increased levels of CK19 mRNA in oral squamous cell carcinoma tissue detected by relative quantification with real-time polymerase chain reaction

Oral squamous cell carcinoma (OSCC) is the most common malignant tumour in the oral and maxillofacial region and has a poor prognosis. Cytokeratin 19 (CK19) is a component of cytoskeleton protein. Previous studies have reported abnormal expression of CK19 protein in OSCC tissue. This study is to investigate the quantitative level of CK19 gene transcript in OSCC tissue as well as its clinical significance. Thirty-one OSCC patients (26 males and 5 females) took part in the present study, aged 34-78 years (mean 58.2 years). The level of CK19 mRNA was detected using fluorescent quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR) in cancerous and paracancerous tissues. The relative quantification in cancerous tissue compared with paracancerous tissue was calculated using the 2(-DeltaDeltaCt) equation. The level of CK19 mRNA in cancerous tissue from OSCC patients was 2.21-fold higher than that in paracancerous tissue (P=0.020), and the amplicon was specific without genomic DNA contamination. The level of CK19 mRNA correlated significantly with the pathological differentiation grade of OSCC tissue (P=0.025), with poorer differentiation indicating a higher level of CK19 mRNA. These results suggest that fluorescent quantitative real-time RT-PCR is accurate and reliable for the detection of CK19 gene transcript levels in OSCC tissue. The level of CK19 mRNA was increased in OSCC tissue, and this was significantly correlated with the pathological differentiation grade.

cDNA microarray analysis of isogenic paclitaxel- and doxorubicin-resistant breast tumor cell lines reveals distinct drug-specific genetic signatures of resistance

cDNA microarray analysis is a highly useful tool for the classification of tumors and for prediction of patient prognosis to specific cancers based on this classification. However, to date, there is little evidence that microarray approaches can be used to reliably predict patient response to specific chemotherapy drugs or regimens. This is likely due to an inability to differentiate between genes affecting patient prognosis and genes that play a role in response to specific drugs. Thus, it would be highly useful to identify genes whose expression correlates with tumor cell sensitivity to specific chemotherapy agents in a drug-specific manner. Using cDNA microarray analysis of wildtype MCF-7 breast tumor cells and isogenic paclitaxel-resistant (MCF-7(TAX)) or doxorubicin-resistant (MCF-7(DOX)) derivative cell lines, we have uncovered drug-specific changes in gene expression that accompany the establishment of paclitaxel or doxorubicin resistance. These changes in gene expression were confirmed by quantitative reverse transcription polymerase chain reaction and immunoblotting experiments, with a confirmation rate of approximately 91-95%. The genes identified may prove highly useful for prediction of response to paclitaxel or doxorubicin in patients with breast cancer. To our knowledge this is the first report of drug-specific genetic signatures of resistance to paclitaxel or doxorubicin, based on a comparison of gene expression between isogenic wildtype and drug-resistant tumor cell lines. Moreover, this study provides significant insight into the wide variety of mechanisms through which resistance to these agents may be acquired in breast cancer.

Immunohistochemical panel of antibodies in the diagnosis of brain metastases of the unknown primary

The primary tumor of brain metastases (BM) is unknown in up to one-half of BM at the time of neurosurgery. Fifty-four consecutive unselected BM were investigated immunohistochemically using antibodies against different intermediate filaments and tumor markers. By correlating the immunohistochemical results with the location of the primary tumor, a staining pattern characteristic of the most frequent BM could be established. Subsequently, 40 cases with known primary tumor were blinded and re-evaluated based on their immunohistochemical staining pattern. Lung (20.4%), colorectum (11.1%), melanoma (7.4%), and breast (7.4%) were the most common primaries. In 14 (25.9%) cases, the primary was unknown. The characteristic immunohistochemical profiles of BM were found to be positivity of cytokeratin 7 and thyroid transcription factor-1 (TTF-1) pointing to the lung, positivity of cytokeratin 20 and negativity of cytokeratin 7 pointing to the colorectum, positivity of vimentin and protein S100 and negativity of cytokeratins (CK) pointing to a melanoma, and positivity of cytokeratin 7 and CA 15-3 with negativity of TTF-1, CA 125 and CA 19-9 pointing to the breast. These primaries comprise the majority in our series. Using the established panel of immunohistochemical markers, we were able to identify the primary in 29 out of 40 (72.5%) BM correctly. To predict the primaries of BM, a combination of antibodies against different CK, vimentin, protein S100, TTF-1, and CA 15-3 is able to point to the primary site in BM of the unknown primary.

Expression of TTF-1 and cytokeratins in primary and secondary epithelial lung tumours: correlation with histological type and grade

AIMS

To assess cytokeratin (CK) and thyroid transcription factor (TTF)-1 expression in primary epithelial lung tumours by comparison with non-pulmonary carcinomas and to correlate it with their histological type and grade.

METHODS AND RESULTS

Immunohistochemistry using antibodies against CKs 5/6, 7, 19, 20 and TTF-1 was applied to 165 primary and 37 secondary epithelial lung tumours. CK5/6 is a sensitive and specific marker of lung squamous carcinomas being positive in 100% of cases. CK7 is a common marker of primary lung adenocarcinomas (100% of cases) but with a lower specificity since it is also observed in other primary lung carcinomas (70% of large-cell neuroendocrine carcinomas, 40% of large-cell carcinomas, 23% of squamous carcinomas) but also in 27% of non-pulmonary adenocarcinomas. Addition of an anti-CK20 may be useful to prove or disprove the pulmonary origin of an adenocarcinoma when there is a history of colon cancer. CK19 is ubiquitous but a predominant or exclusive 'dot-like' pattern is very suggestive of high-grade neuroendocrine carcinoma. TTF-1 is a very sensitive and specific marker to document the pulmonary origin of an adenocarcinoma if a thyroid origin is excluded. Its expression in neuroendocrine lung tumours depends on the tumour grade.

CONCLUSIONS

Immunohistochemical expression of CKs and TTF-1 may be correlated with histological type and grade of lung primary epithelial tumours and may allow them to be distinguished from non-pulmonary carcinomas.

Monitoring of therapy in head and neck patients during the radiotherapy by measurement of Cyfra 21-1

PURPOSE

Cyfra 21-1, measuring serum fragments of cytokeratin 19, has been found to be related to tumour stage and tumour size in patients with cervical cancer. It could be a promising marker in squamous lung cancer. We evaluated this new marker with carcinoembryonic antigen, (CEA) and squamous cell carcinoma antigen (SCC-Ag) in the monitoring of 27 patients with head and neck cancer.

PATIENTS AND METHODS

The retrospective study group consisted of 27 patients, 17 not suited for surgery and 10 after laser resection. Patients were clinically staged according to the TNM-classification. The mean age of the patients was 53 years (range 37-70 years). Serum levels of each marker were studied in relation to tumour stage and clinical status of the patients during radiotherapy and 6 weeks after the end of the treatment. The clinical performance of the various assays to separate those patients with complete remission from those patients with the presence of tumour was assessed.

RESULTS

Pre-treatment serum Cyfra 21-1, CEA, and SCC-Ag levels were not related to stage of disease and were not found to be predictive of tumour response. The clinical performance of post-treatment serum SCC-Ag levels in predicting the presence of tumour was not better than the Cyfra 21-1 assays.

CONCLUSION

We could not conclude from this study that Cyfra 21-1 marker is an additional parameter in identifying patients at risk of residual tumour after treatment, recurrent or progressive disease. An elevation of cyfra 21-1 marker was not detectable in 70% of the cases with macroscopic tumour. Therefore, Cyfra 21-1 is not a reliable parameter for the monitoring of patients with head and neck cancer during radiotherapy.

Cytokeratin expression patterns in jaw cyst linings with metaplastic epithelium

BACKGROUND

Cytokeratin (CK) expression patterns have been studied in numerous intact and diseased oral tissues. However, CK expression in metaplastic squamous cells has not been explored in depth and the origin of metaplastic epithelial linings of the jaw cysts has not been sufficiently investigated.

METHODS

We examined CK expression in 46 postoperative maxillary cysts (POMCs) which were lined with pseudostratified columnar cells only, columnar and squamous cells, and squamous cells only, in 13, 30 and 3 cases, respectively.

RESULTS

The expression of CK8, CK13 and CK18 were observed in 39, 9 and all 43 of the columnar epithelial linings, respectively. Metaplastic squamous epithelia expressed more CK13, and less CK18 and CK8. Of the 33 metaplastic linings, 24 expressed CK8, 23 CK13 and 26 linings expressed CK18. The patterns of expression of CK13 and CK18 observed were CK18(+)-CK13(-) in 10 metaplastic linings, CK18(+)-CK13(+) in 16, and CK18(-)-CK13(+) in 7. The expression of CK13- and CK18-mRNA was generally correlated with level of protein expressed. CK18-mRNA expression was observed by in situ hybridization, not only in the 26 metaplastic linings which were positive for CK18 protein, but also in five of the seven metaplastic linings which did not express CK18 protein. In addition, RT-PCR revealed an expression of CK18-mRNA in all metaplastic squamous linings, although the expression level was weaker than that in the columnar epithelial linings. The CK13-mRNA was expressed inversely to the CK18-mRNA.

CONCLUSIONS

These results indicate that CK18-mRNA is preserved through metaplasia, although the protein expression decreased. Metaplastic squamous cells differentiate with a decrease of CK18 and an increase of CK13 expression.

Expression of cytokeratins (CKs) 8, 13 and 18 and their mRNA in epithelial linings of radicular cysts: implication for the same CK profiles as nasal columnar epithelium in squamous epithelial lining

OBJECTIVE

Our objective was to specify cytokeratin (CK) patterns in lining epithelia of radicular cysts which are sometime lined with ciliated columnar epithelia as seen in the nasal epithelia.

MATERIALS AND METHODS

We examined the CK expression in 52 radicular cysts obtained from 32 maxillary and 20 mandibular lesions and investigated CK-mRNA expression using in situ hybridization in 24 maxillary and 13 mandibular cysts and reverse transcription-polymerase chain reaction (RT-PCR) in 24 maxillary cysts.

RESULTS

Of the maxillary cysts, 20, 29 and 19 squamous epithelial linings were positive for CK8, CK13 and CK18, respectively; of the mandibular cysts, 10, 20 and 11 linings were positive for these CKs, respectively. The expression patterns of CK18(+)-CK13(-), CK18(+)-CK13(+) and CK18(-)-CK13(+) were observed in 3, 16 and 13 linings of the maxillary cysts and 0, 11 and 9 linings of the mandibular cysts, respectively. In situ hybridization revealed the expression of CK18-mRNA in 9 and 4 linings of 24 maxillary and 13 mandibular cysts examined, respectively. With RT-PCR, we explored that both CK18- and CK13-mRNA were expressed not only in the normal nasal and gingival epithelia but also in the examined maxillary cyst linings although their expression levels differed correlating with the difference in CK staining.

CONCLUSION

It is concluded that CK13- and CK18-mRNA are constitutively expressed in columnar and squamous epithelial cells, respectively, and that the variant CK expression patterns with CK18-mRNA expression in maxillary radicular cysts are indicative of the possibility of phenotypic transformation in the cyst linings.

Keratin mRNA for detecting micrometastasis in cervical lymph nodes of oral cancer

We studied three keratin (K) gene candidates, K13, K19, and K20 mRNAs, for detecting micrometastases in cervical lymph nodes (LNs) by reverse transcriptase-polymerase chain reaction (RT-PCR). Of 166 histologically metastasis-negative nodes, 24 micrometastatic LNs (14. 4%) were detected based on K13 gene expression. Keratin 19 mRNA is an inadequate marker for the genetic diagnosis due to not only illegitimate gene expression from lymphatic tissue but also gene expression from the ectopic salivary gland. Keratin 20 mRNA showed low sensitivity. It is suggested that K13 mRNA may be a promising tumor marker among these keratin genes for detecting the micrometastases in cervical LNs of oral cancer.