Natcha Patarapadungkit

Differential methylation of E2 binding sites in episomal and integrated HPV 16 genomes in preinvasive and invasive cervical lesions

Enhanced expression of the HPV 16 E6‐E7 oncogenes may trigger neoplastic transformation of the squamous epithelial cells at the uterine cervix. The HPV E2 protein is a key transcriptional regulator of the E6‐E7 genes. It binds to four E2 binding sites (E2BSs 1–4) in the viral upstream regulatory region (URR). Modification of E2 functions, for example, by methylation of E2BSs is hypothesized to trigger enhanced expression of the viral E6‐E7 oncogenes. In the majority of HPV‐transformed premalignant lesions and about half of cervical carcinomas HPV genomes persist in an extra‐chromosomal, episomal state, whereas they are integrated into host cells chromosomes in the remaining lesions. Here we compared the methylation profile of E2BSs 1–4 of the HPV 16 URR in a series of 18 HPV16‐positive premalignant lesions and 33 invasive cervical cancers. CpGs within the E2BSs 1, 3, and 4 were higher methylated in all lesions with only episomal HPV16 genomes compared with lesions displaying single integrated copies. Samples with multiple HPV16 integrated copies displayed high methylation levels for all CpGs suggesting that the majority of multiple copies were silenced by extensive methylation. These data support the hypothesis that differential methylation of the E2BSs 1, 3 and 4 is related to the activation of viral oncogene expression in cervical lesions as long as the viral genome remains in the episomal state. Once the virus becomes integrated into host cell chromosomes these methylation patterns may be substantially altered due to complex epigenetic changes of integrated HPV genomes.

Up-Regulation of miR-21 Is Associated with Cervicitis and Human Papillomavirus Infection in Cervical Tissues

MicroRNA-21 (miR-21) is recognized as an oncomir and shows up-regulation in many types of human malignancy. The aim of this study was to investigate the association of miR-21 expression associated with HPV infection in normal and abnormal cervical tissues. Cervical tissue samples with different cytological or histopathological grades were investigated for HPV by PCR and for miR-21 and programmed cell death, protein 4 (PDCD4) expression using quantitative real-time PCR (qRT-PCR). Laser capture microdissection (LCM) of stromal and epithelial tissues and in situ hybridization (ISH) using locked nucleic acid (LNA) probes were performed on a subset of fixed specimens. Cell line experiments were conducted on fibroblasts stimulated in culture media from HeLa cells, which were then assessed for miR-21, PDCD4, IL-6 and α-SMA expression by qRT-PCR. Twenty normal cervical cell, 12 cervicitis, 14 cervical intraepithelial neoplastic I (CIN I), 22 CIN II-III and 43 cervical squamous cell carcinoma (SCC) specimens were investigated. miR-21 levels were significantly lower in normal than in abnormal tissues. The expression of miR-21 in HPV negative normal cytology was significantly lower than in HPV positive samples in abnormal tissue and SCC. The miR-21 expression was significantly higher in HPV negative cervicitis than HPV negative normal cells. LCM and ISH data showed that miR-21 is primarily expressed in the tumor-associated stromal cell microenvironment. Fibroblasts treated with HeLa cell culture media showed up-regulated expression of miR-21, which correlated with increased expression of α-SMA and IL-6 and with down-regulation of PDCD4. These results demonstrate that miR-21 is associated with HPV infection and involved in cervical lesions as well as cervicitis and its up-regulation in tumor-stroma might be involved in the inflammation process and cervical cancer progression.

Possible contributing role of Epstein-Barr virus (EBV) as a cofactor in human papillomavirus (HPV)-associated cervical carcinogenesis

BACKGROUND Persistent infection with EBV has been linked to the development of malignancies including HPV-associated cervical carcinoma. However, the role of EBV in HPV-associated cervical cancer is still poorly understood. OBJECTIVE To determine the possible contributing role of EBV in HPV-associated cervical carcinogenesis according to HPV genotypes, HPV genome status and EBV localization. STUDY DESIGN Cervical tissues, including 82 with no squamous intraepithelial lesions (noSILs), 85 low-grade SILs (LSILs), 85 high grade SILs (HSILs) and 40 squamous cell carcinoma samples (SCC) were investigated using PCR and dot blot hybridization for EBV detection and PCR and reverse line blot hybridization for HPV genotyping. The amplification of papillomavirus oncogene transcripts assay and in situ hybridization were used to determine HPV physical status and EBV EBER localization, respectively. RESULTS EBV was detected increasingly from noSIL (13.4%), LSIL (29.4%) to HSIL (49.4%) samples. The prevalence of HPV-EBV co-infection was significantly higher in any grade of lesion than in noSIL samples (p<0.05) including noSIL (1.2%; 95% confidence intervals [CI]=0.0-3.6%, relative risk [RR]=1), LSIL (18.8%, 95% CI=10.5-27.1%, RR=15.4), HSIL (41.2%, 95% CI=30.7-51.6%, RR=33.8) and SCC (30.0%, 95% CI=15.8-44.2%, RR=24.6). Interestingly, HPV-EBV co-infection was more common in cases with episomal forms of high-risk (HR) HPV whereas HPV alone was more common in cases with integrated HR-HPV. In addition, EBER staining demonstrated that EBV was mainly present in infiltrating lymphocytes. CONCLUSION Infiltrating EBV-infected lymphocytes may play a role in cancer progression of cervical lesion containing episomal HR-HPV.

Anal Cancer Screening by Modified Liquid-Based Cytology in an HIV Clinic

This study aimed to screen for anal cancer and to determine its cytomorphology using liquid-based cytology (LBC) with specimens preserved in 95% ethyl alcohol. Anal swabs were collected for cytological examination from 177 adult, HIV-infected patients. After collection, sample slides were reviewed and classified according to their cytomorphology using the modified Bethesda 2001 system. An abnormal anal Pap smear was found in 26.0% of the patients. The diagnoses were: 66.7% negative for intraepithelial lesions (NIL), 14.1% with atypical squamous cells of undetermined significance (ASC-US), 10.7% (19) with low-grade squamous intraepithelial lesions (LSIL), and 1.13% with high-grade squamous intraepithelial lesions (HSIL). The cytological evaluation was an unsatisfactory result only with 6.67%. The present modified LBC using 95% ethyl alcohol as the preservative could thus be used for anal cancer screening. The number of SILs in Thai HIV-infected patients is lower than that in Western countries. We found anal cytology a satisfactory tool for early screening and detection of anal dysplasia commonly found in high-risk, HIV-infected patients.

The three most common human papillomavirus oncogenic types and their integration state in Thai women with cervical precancerous lesions and carcinomas

To understand the potential role in cervical cancer development of the three most common high‐risk human papillomavirus (HR‐HPVs) in Thai women, HPV genotypes and viral genome statuses in different cervical lesions were investigated. Cervical tissues consisting of no cervical intraepithelial neoplasia (84 cases), grade I cervical intraepithelial neoplasia (176 cases), grade II–III cervical intraepithelial neoplasia (91 cases), and squamous cell carcinoma (66 cases) were subjected for HPV genotyping by polymerase chain reaction (PCR) and reverse line blot hybridization assay and for HPV genome status determination by amplification of papillomavirus oncogene transcripts (APOT) assay. HPV prevalence was 28.6% in no cervical intraepithelial neoplasia, 40.3% in grade I cervical intraepithelial neoplasia, 70.3% in grade II–III cervical intraepithelial neoplasia and 86.4% in squamous cell carcinoma cases. The three most common HR‐HPV types were HPV 16, 58, and 18 which were distributed in all cervical lesions. HPV physical statuses could be investigated in 4 no cervical intraepithelial neoplasias, 2 grade I cervical intraepithelial neoplasias, 28 grade II–III cervical intraepithelial neoplasias and 31 squamous cell carcinomas. The integrated‐derived transcripts were found 3.6% in grade II–III cervical intraepithelial neoplasia and 48.4% in squamous cell carcinoma, whereas no viral genome integration was found in the group of no cervical intraepithelial neoplasia or grade I cervical intraepithelial neoplasia samples. The frequencies of HR‐HPV integration in squamous cell carcinoma were found 40%, 100%, 20% of HPV 16, 18, and 58. This study indicates the oncogenic potential ability of the three most common HR‐HPVs associated with cervical cancer progression. J. Med. Virol. 86:1911–1919, 2014.

Human papillomavirus (HPV) infection in a case-control study of oral squamous cell carcinoma and its increasing trend in northeastern Thailand

Human papillomavirus (HPV) is an independent risk factor for development of oral squamous cell carcinoma (OSCC). This study aimed to investigate the role of HPV infection and the trend in percentage of HPV‐associated OSCC over a 5‐year period in northeastern Thailand. In this case‐control study, 91 exfoliated oral cell samples and 80 lesion cell samples from OSCC cases and exfoliated oral cells from 100 age/gender‐matched controls were collected. HPV infection was investigated by PCR using GP5+/GP6+ primers followed by HPV genotyping using reverse line blot hybridization. Quantitative RT‐PCR was used to evaluate HPV oncogene transcription. Temporal trends of HPV infection were evaluated in archived formalin‐fixed paraffin‐embedded (FFPE) OSCC tissues using in situ hybridization. HPV DNA was found in 17.5% (14/80) of lesion samples from OSCC cases and 29.7% (27/91) of exfoliated oral cell samples from the same cases. These values were significantly higher than in exfoliated oral cell samples from controls (13%, 13/100). HPV‐16 was the genotype most frequently found in OSCC cases (92.8%, 13/14 infected cases). Interestingly, HPV oncogene mRNA expression was detected and correlated with OSCC cases (P < 0.005). Of 146 archived FFPE OSCC samples, 82 (56.2%) were positive for high‐risk HPV DNA and 64 (43.8%) cases were positive for HPV E6/E7 mRNA expression. There was a trend of increasing percentage of HPV‐associated OSCC from 2005 to 2010. This was especially so for females with well‐differentiated tumors in specific tongue sub‐sites. We suggest that HPV infection plays an important role in oral carcinogenesis in northeastern Thailand.

Effects of arecoline on proliferation of oral squamous cell carcinoma cells by dysregulating c-Myc and miR-22, directly targeting oncostatin M

Arecoline, the major alkaloid of areca nut, is known to induce oral carcinogenesis, however, its mechanism is still needed to elucidate. This study investigated the effects of arecoline on cell viability and cell-cycle progression of oral squamous cell carcinoma (OSCC) cells as well as a relevant cellular gene expression. The results showed that a low concentration of arecoline (0.025 μg/ml) increased OSCC cell viability, proportion of cells in G2/M phase and cell proliferation. Simultaneously, it induced IL-6, STAT3 and c-Myc expression. Interestingly, c-myc promoter activity was also induced by arecoline. MiR-22 expression in arecoline-treated OSCC cells was suppressed and comparable to an upregulated c-Myc expression. In arecoline-treated OSCC cells, oncostatin M (OSM) expression was significantly upregulated and inversely correlated with miR-22 expression. Likewise, OSM expression and its post-transcriptional activity were significantly decreased in miR-22-transfected OSCC and 293FT cells. This result demonstrated that miR-22 directly targeted OSM. Interestingly, miR-22 played an important role as a tumor suppresser on suppressing cell proliferation, migration and cell-cycle progression of OSCC cells. This result suggested the effect of arecoline to promote cell proliferation and cell-cycle progression of OSCC cells might be involved in induction of c-Myc expression and reduction of miR-22 resulting in OSM upregulation.

Amplification of EGFR and cyclin D1 genes associated with human papillomavirus infection in oral squamous cell carcinoma

Human papillomavirus (HPV) infection is associated with several genetic alterations including oncogene amplification, leading to increased aggression of tumors. Recently, a relationship between HPV infection and oncogene amplification has been reported, but this finding remains controversial. This study therefore investigated relationships between HPV infection and amplification of genes in the epidermal growth factor receptor (EGFR) signaling cascade in oral squamous cell carcinoma (OSCC). Extracted DNA from 142 formalin-fixed paraffin-embedded (FFPE) OSCC tissues was performed to investigate the copy number of EGFR, KRAS, c-myc and cyclin D1 genes using real-time polymerase chain reaction (RT-PCR) and compared with calibrators. A tissue microarray of OSCC tissues was used for detection of c-Myc expression and HPV infection by immunohistochemistry and HPV E6/E7 RNA in situ hybridization, respectively. HPV infection was also investigated using PCR and RT-PCR. Of the 142 OSCC samples, 81 (57%) were HPV-infected cases. The most frequently amplified gene was c-myc (55.6%), followed by cyclin D1 (26.1%), EGFR (23.9%) and KRAS (19.7%). Amplification of c-myc was significantly associated with levels of its protein product. EGFR amplification was also significantly associated with amplification of genes in the signaling cascade: KRAS (50.0%), c-myc (34.2%) and cyclin D1 (46.0%). Interestingly, HPV infection was significantly associated with amplification of both EGFR (76.5%) and cyclin D1 (73.0%). Only cyclin D1 amplification was significantly associated with severity of OSCC histopathology. HPV infection may play an important synergistic role in amplification of genes in the EGFR signaling cascade, leading to increased aggression in oral malignancies.

Methylation Status of P16Ink4a in Human Papillomavirus-Associated Cancer of Oral Cavity and Oropharynx in Northeastern Thailand

Background: Over-expression of p16INK4a protein is a biomarker for human papillomavirus (HPV)-associated cervical cancer. However, absence of p16INK4a protein expression in HPV-associated cancer of the oral cavity and oropharynx has been reported. Among a number of possible reasons for this is methylation, which is frequently noted in the promoter region of p16INK4a and is associated with silencing of the gene and disease severity. Methods: We investigated the relationships between p16INK4a protein expression, HPV infection and methylation status of the p16INK4a promoter in cancers of the oral cavity and oropharynx. Fifty-three formalin-fixed paraffin-embedded (FFPE) cancer tissue samples from the oral cavity (49 cases) and oropharynx (4 cases) were studied. P16INK4a protein expression was determined using immunohistochemical staining (IHC). Additional oral tissues lacking squamous intraepithelial lesions (SILs), and cervical tissues with high-level SILs, were used as negative and positive controls, respectively. High-risk HPV infection was detected using HPV E6/E7 mRNA in situ hybridization. Methylation status of the p16INK4a promoter was investigated using sodium bisulfite treatment and methylation-specific PCR (MS-PCR). Results: HPV infection was found in 40.8% (20/49) and 50.0% (2/4) of oral cavity and oropharynx cancers, respectively. Promoter methylation of p16INK4a occurred in 73.6 % of all cases and differed significantly in frequency between HPV-positive (90.9%, 20/22) and HPV-negative (61.3%, 19/31) samples. Expression of p16INK4a was found in 35.8% (19/53) and commonly detected in samples with p16INK4a unmethylation (79.5%). Interestingly, the silencing of p16INK4a (64.2%, 34/53) was significantly associated with methylation status (91.2%, 31/34), especially in HPV-infected samples in which the p16INK4a promoter was methylated (52.9%, 18/34). Conclusions: This result demonstrated high frequency of p16INK4a promoter methylation status in HPV-associated HNSCC subsets that could influence the silent p16INK4a expression and might promote disease severity.

Effect of human papillomavirus 16 oncoproteins on oncostatin M upregulation in oral squamous cell carcinoma

Human papillomavirus (HPV) infection modulates several host cytokines contributing to cancer development. Oncostatin M (OSM), an IL-6 family cytokine, acts to promote cell senescence and inhibit growth. Its dysregulation promotes cell survival, cell proliferation and metastasis in various malignancies. The effect of HPV on OSM dysregulation has not been investigated. To elucidate this, immunohistochemistry was used on formalin-fixed, paraffin-embedded oral squamous cell carcinoma (OSCC) tissues: HPV-positive (50) and HPV-negative (50) cases. Immortalized human cervical keratinocytes expressing HPV16E6 (HCK1T, Tet-On system) were used to demonstrate the role of HPV16E6 in OSM expression. In addition, a vector containing HPV16E6/E7 was transiently transfected into oral cancer cell lines. Cell viability, cell-cycle progression and cell migration were evaluated using flow cytometry and a wound healing assay, respectively. The results showed various intensities of OSM expression in OSCC. Interestingly, the median percentages of strongly stained cells were significantly higher in HPV-positive OSCCs than in HPV-negative OSCCs. To explore the role of HPV oncoproteins on OSM expression, the expression of HPV16E6 in the HCK1T Tet-On condition was induced by doxycycline and HPV16E6 was found to significantly upregulate levels of OSM mRNA and protein, with concomitant upregulation of c-Myc. In addition, the levels of OSM mRNA and protein in E6/E7 transiently transfected oral cancer cells also gradually increased in a time-dependent manner and these transfected cells showed greater viability and higher migration rates and cell-cycle progression than controls. This result demonstrates that HPV16 oncoproteins upregulate OSM and play an important role to promote OSCC development.