Type-specific Oligonucleotide Probes Research Articles

Presence of high risk HPV DNA but indolent transcription of E6/E7 oncogenes in invasive ductal carcinoma of breast

Background and aimsThe causative role of high risk human papillomavirus (HR-HPV) in breast cancer development is controversial, though a number of reports have identified HR-HPV DNA in breast cancer specimens. Nevertheless, most studies to date have focused primarily on viral DNA rather than the viral transcription. The aim of this study was to investigate the presence of HR-HPV in breast cancer tissues at HPV DNA level and HPV oncogenes mRNA level by in situ hybridization (ISH). MethodsOne hundred and forty six (146) cases of breast invasive ductal carcinoma(IDC) and 83 cases of benign breast lesions were included in the study. Type specific oligonucleotide probes were used for the DNA detection of HPV 16,18 and 58 by ISH. HR-HPV oncogenes mRNA was assayed by novel RNAscope HR-HPV HR7 assay ISH. p16 protein expression was evaluated by immunohistochemistry (IHC). ResultsHR-HPV 16,18 and 58 DNA were detected in 52 out of 146 (35.6%) IDC and in 3 out of 83 (3.6%) benign breast lesions by ISH. The HR-HPV mRNAs was detected only in a few specimens with strong HPV DNA positivity(4/25) in a few scattered cancer cells with very weak punctate nuclear and/or cytoplasmic staining. p16 over-expression did not correlate with the HPV DNA positive breast cancer samples(17/52 HPVDNA+ vs 28/94 HPV DNA-, p=0.731). ConclusionsHR-HPVs certainly exist in breast cancer tissue with less active transcription, which implies that the causal role of HPV in breast cancer development need further study.

Prevalence and risk factors for oral human papillomavirus infection in 129 women screened for cervical HPV infection

Oncogenic human papillomaviruses (HPV) are known to be associated with carcinomas of the uterine cervix. Furthermore, current studies have shown that HPV-infection is also associated with a subtype of oropharyngeal cancers. In general, a sexual transmission of the viruses has been shown by numerous studies in the genital lesions. However, there are unknown factors regarding the prevalence and transmission of HPV in the oropharynx. The aim of this study was to evaluate HPV prevalence in the oropharynx in female participants with and without genital HPV infection. In addition, we analyzed risk factors for an oropharyngeal colonization with HPV in their sexual partners, too. 129 Female participants were tested for presence of HPV-DNA by oral lavage, brush cytology of the tonsils and of the cervix. In addition, 15 male partners of these patients were included in the study. HPV-DNA was detected by PCR (polymerase chain reaction) amplification. For HPV-genotyping, PCR products were hybridized with type-specific digoxigenin-labeled oligonucleotide probes and discriminated into 14 high risk (HR) and 6 low risk (LR)-HPV types. The 129 female and 15 male participants were interviewed by a standardized questionnaire for socioeconomic details, drinking, smoking and sexual behaviours. 59 (45.7%) Female participants were negative for a genital HPV-infection. Of these women, 3 (5.1%) showed a positive HPV-PCR result (HR and LR) in the oropharynx. 70 (54.3%) Female participants were positive for a genital HPV infection. In this group, 4 (5.7%) had a positive HPV-detection (HR and LR) in the oral cavity and oropharynx. Female participants with cervical HPV-infection had no higher risk for HPV-detection in the oropharynx (not significant). The analysis of sexual risk factors revealed no specific risk factor for an oral HPV-infection. A correlation between cervical and oral colonization by HPV could not be demonstrated in our small cohort. Our limited data suggest that sexual transmission of HPV from the cervix uteri to the oropharynx is a rare and unlikely event.

Bead-Based Multiplex Genotyping of 58 Cutaneous Human Papillomavirus Types

Cutaneous human papillomaviruses (HPVs) are a heterogeneous, nonmonophyletic assembly, comprising about 50 characterized types and at least 133 isolates putatively representing new types. Their natural history of infection and potential association with nonmelanoma skin cancer are not well understood. Several PCR systems have been developed that amplify a broad spectrum of cutaneous HPVs. However, amplicon genotyping by sequencing or reverse line blot assays are complex and not well suited for high-throughput analyses. We developed a novel multiplex cutaneous papillomavirus genotyping (McPG) assay for 38 defined and 20 putative cutaneous HPVs of the beta, gamma, mu, and nu genera. Viral DNA was amplified by the use of a modified single-tube nested "hanging-droplet" FAP PCR. The amplifiable papillomavirus (PV) spectrum was enlarged by the use of 9 outer and 13 inner primers. Biotinylated PCR products were hybridized to type-specific oligonucleotide probes coupled to fluorescence-labeled polystyrene beads and analyzed using Luminex technology. Analytical sensitivity was analyzed for 38 defined HPVs and was ≤100 genome copies for all types. Integrated β-globin primers allow for simultaneous DNA quality control. McPG is characterized by high reproducibility (κ= 0.84, 95% confidence interval = 0.79 to 0.88), good concordance with the original nested FAP PCR, followed by sequencing (70.2% complete or partial agreement) when 322 skin biopsy DNA samples were analyzed, and improved ability to detect multiple infections (on average 2.5 HPV types per HPV-positive sample compared to 1.7 HPV types with nested FAP-PCR). In conclusion, McPG is a powerful tool for genotyping multiple cutaneous HPVs in a high-throughput format and is thus suitable for large-scale epidemiological studies.

Smoking increases the risk of high-grade vaginal intraepithelial neoplasia in women with oncogenic human papillomavirus

Objectives In a large retrospective study, the association of smoking with human papillomavirus (HPV) genotype and vaginal intraepithelial neoplasia (VAIN) grade was analyzed. Methods A SNOMED search was performed for vaginal biopsy or resection specimens diagnosed as VAIN over an 11-year period. The diagnosis of VAIN grade was confirmed by histological review. HPV genotype was determined by GP5+/6+ PCR and dot blot hybridization with type-specific oligonucleotide probes. Smoking history was obtained by chart review. Statistical analysis was performed using the chi-square test. Results We identified specimens from 111 patients (age range 15–84); 64% ( n = 71) were diagnosed with high-grade VAIN (HGVAIN) and 36% ( n = 40) with low-grade VAIN (LGVAIN). High-risk (HR) HPV genotypes were identified in 83% of specimens ( n = 92), other types in 17% ( n = 19). Twenty-one different HPV genotypes were detected in total. Smoking history was available for 81% ( n = 90). Forty-one percent ( n = 37) had a positive smoking history. There was no significant difference in infection with HR vs. other types ( p = 0.92) among smokers when compared to non-smokers. In patients with HR HPV genotypes, smokers were at an increased risk for HGVAIN lesions when compared to patients who had never smoked (83% vs. 59%, p = 0.02). Conclusions These data indicate an increased risk for HGVAIN in HR HPV positive women who smoke compared to HR HPV positive non-smokers.

Association Between HLA‐DRB1 polymorphism, high‐risk HPV infection and cervical neoplasia in southern Chinese

Multiple determinants are involved in the progression of human papillomavirus (HPV)-infected cervical lesion to invasive cancer. Human leukocyte antigen (HLA) polymorphism seems to play a role. This study examined the association between HLA-DRB1 polymorphism, high-risk HPV infection, and the development of cervical neoplasia in southern Chinese. Three hundred and seventy women with cervical neoplasia (43 cervical intraepithelial neoplasia grade II, 154 grade III, and 173 invasive cancers) and 323 controls were recruited for HLA-DRB1 typing by a sequence-based approach. Cervical specimens were collected for HPV detection by a consensus primer-based polymerase chain reaction, and with the type of HPV identified by hybridization with type-specific oligonucleotide probes. A protective effect of HLA-DRB1*12 for cervical neoplasia was observed, and with stronger associations when subgroup analyses were carried out for patients infected with HPV16 and HPV58. The protective effect of HLA-DRB1*13 that had been reported from other populations was not observed. The data obtained in this study showed that HLA-DRB1*03 conferred a higher risk for HPV18-infected, but not for HPV16-, HPV52-, or HPV58-infected cervical lesions. Although, HPV52 was reported as uncommon worldwide, it was found to be the second most prevalent type in the southern Chinese population. However, no additional risk association was observed when subgroup analyses were performed for HPV52-infected patients. The current study shows that, among southern Chinese, the outcome of HPV-infected cervical lesions is associated with HLA-DRB1 polymorphism. These associations often vary with the type of HPV infection.

Polymerase chain reaction‐based fluorescent Luminex assay to detect the presence of human papillomavirus types

Becuase 40% of human papillomavirus (HPV) infections are mixed infections, the accurate identification of high-risk HPV genotypes in mixed infections is important for defining a woman's risk for progression to cervical cancer. Thus, advanced Luminex-based HPV genotyping has been developed to simultaneously detect the presence of multiple HPV types. Here, we describe the development of a Luminex-based HPV genotyping that combines polymerase chain reaction amplification with hybridization to fluorescence-labeled polystyrene bead microarrays (Luminex suspension array technology). New HPV type-specific oligonucleotide probes and YBT L1/GP6-1 primers were used to detect the HPV types in 132 clinical samples. We simultaneously evaluated the usefulness of this technique on clinical samples. We detected 15 specific HPV types (6, 16, 18, 31, 35, 42, 51, 52, 55, 56, 58, 59, 66, 67 and 68) examined with specificity without known cross-reaction to other HPV types. The detection limit for the different HPV types was above 500 plasmids. We compared the performance of the Luminex-based assay to the established HPV DNA microarray chip for polymerase chain reaction products derived from 53 clinical samples. The evaluation showed excellent agreement. The Luminex-based HPV genotyping was a sensitive, reproducible technique for the simultaneous genotyping of all clinically relevant genital HPV types. This assay system may be used to provide critical clinical information for early detection of HPV, especially in cases where the HPV copy numbers are low and the latency period of HPV infection is prolonged.

Detection of hepatitis B virus genotypes using oligonucleotide chip among hepatitis B virus carriers in Eastern China

To determine the genotype distribution of hepatitis B virus (HBV) with a newly oligonucleotide chip assay among the HBV carriers in Eastern China. An assay using oligonucleotide chip was developed for detection of HBV genotypes in serum samples from HBV DNA-positive patients in Eastern China. This method is based on the principle of reverse hybridization with Cy5-labeled amplicons hybridizing to type-specific oligonucleotide probes that are immobilized on slides. The results of 80 randomly chosen sera were confirmed by direct sequencing. HBV genotype B, C and mixed genotype were detected in 400 serum samples, accounting for 8.3% (n = 33), 83.2% (n = 333), and 8.5% (n = 34), respectively. The evaluation of the oligonucleotide assay showed 100% concordance with the amplicon phylogenetic analysis except 9 mixed genotype infections undetected by sequencing. The study indicates that HBV genotype C and B prevail in the Eastern China. It is suggested that the oligonucleotide chip is a reliable and convenient tool for the detection of HBV genotyping.

Detection and typing of 46 genital human papillomaviruses by the L1F/L1R primer system based multiplex PCR and hybridization

There are several genital HPV DNA detection systems described, however most of them present different disadvantages regarding the number of amplified and detected types, sensitivity, type specificity. A new PCR and hybridization based detection method was developed for sensitive and balanced amplification and specific typing of HPV DNA from clinical samples. The technique amplifies and detects 46 HPV types: 2a, 3, 6, 7, 10, 11, 13, 16, 18, 26, 27, 28, 29, 30, 31, 33, 34, 35, 39, 40, 42, 43, 44/55, 45, 51, 52, 53, 54, 56, 57, 58, 59, 61, 66, 67, 68, 70, 72, 73(MM9), 74, 82(MM4), 84(MM8), 89, 90, 91. Key elements of the L1F/L1R PCR and hybridization system are: the special selection of the amplified region, a novel and optimized amplification primer set, circumspectly designed general and type-specific oligonucleotide probes. Detection following a multiplex PCR is based on solid phase hybridization in microtiter plate format using general and type-specific probes at medium stringency, which makes the detection robust in case of small sequence variations. The assay is highly reproducible and suitable for automation. The method was compared to Hybrid Capture II test, and after clarifying conflicting results, the comparison showed an excellent agreement (96.2%).

Oligonucleotide Microarray with RD-PCR Labeling Technique for Detection and Typing of Human Papillomavirus

Currently, screening for high-risk human papillomavirus (HPV) infection remains an important health concern throughout the world, because of the close association between certain types of HPV and cervical cancer. In this study, we explore the possibility of using approximately 70mer oligonucleotide microarray for detection and genotyping of HPV. The approximately 70mer type-specific oligonucleotide probes of four different types HPV were designed by using biological software Array designer 2.0, which analyzed the whole genome sequences of HPV and selected optimal probes. These probes were synthesized and printed onto the surface of glass slides in order to prepare a low-density microarray. HPV samples were labeled with fluorescence dyes Cy3 using a method of restriction display polymerase chain reaction (RD-PCR). HPV plasmid DNA was restricted with Sau3A I to produce multiple fragments that were ligated to adaptors subsequently and used as PCR template. PCR labeling was performed with the fluorescently labeled universal primer (Cy3-UP) whose sequence is designed according to the adaptor of the RD-PCR approaches. The labeled samples were hybridized with the oligonucleotide microarray. The scanning results showed that HPV DNA hybridized specifically with multiple spots correspondingly to show positive signals, whereas no signals were detected of all the negative and blank controls. These results demonstrated that approximately 70mer oligonucleotide microarray can be applied to HPV detection and genotyping. The application of RD-PCR in the sample labeling can increase significantly the sensitivity of the assay and will be especially useful for the discriminate diagnosis of multiple pathogens.

Bead-Based Multiplex Genotyping of Human Papillomaviruses

Typing of human papillomaviruses (HPV) by DNA hybridization procedures, such as reverse line blot (RLB) assay, is sensitive and well validated. However, the application of these assays to high-throughput analyses is limited. Here, we describe the development of multiplex human papillomavirus genotyping (MPG), a quantitative and sensitive high-throughput procedure for the identification of multiple high- and low-risk genital HPV genotypes in a single reaction. MPG is based on the amplification of HPV DNA by a general primer PCR (GP5+/6+) and the subsequent detection of the products with type-specific oligonucleotide probes coupled to fluorescence-labeled polystyrene beads (Luminex suspension array technology). Up to 100 different HPV types can be detected simultaneously with MPG, and the method is fast and labor saving. We detected all 22 HPV types examined with high specificity and reproducibility (the median interplate coefficient of variation was below 10%). Detection limits for the different HPV types varied between 100 and 800 pg of PCR products. We compared the performance of MPG to an established RLB assay on GP5+/6+-PCR products derived from 94 clinical samples. The evaluation showed an excellent agreement (kappa = 0.922) but also indicated a higher sensitivity of MPG. In conclusion, MPG appears to be highly suitable for large-scale epidemiological studies and vaccination trials as well as for routine diagnostic purposes.

Prevalence and typing of human papilloma virus (HPV) among female sex workers and outpatient women in southern Thailand

Thai sex workers (SW) have high rates of sexually transmitted infections (STIs); however, detection and treatment is often complicated by accessibility to sensitive and accurate diagnostic tests. Self-sampling of women combined with molecular amplification techniques could help in accurate diagnosis, treatment and follow-up of such women. Detection of persistent high-risk human papilloma virus (HPV) in such populations could also be beneficial in identifying women who may need more frequent follow-up for cervical cytology screening. The current study aimed to examine the prevalence of HPV in this population and compare this with the lower-risk outpatient women (OPW) in Thailand. Four hundred and thirty OPW and 524 Thai SW were sampled by a self-administered tampon collection. Cells were extracted from tampons and, subsequently, women underwent routine vaginal examination for detection of other STIs. Detection of HPV was performed by polymerase chain reaction (PCR) using the L1 consensus primers, followed by L1 consensus probe using an in-house PCR-enzyme-linked immunosorbent assay (ELISA). All positive samples were typed using PCR-ELISA and type-specific oligonucleotide probes. Overall, HPV was detected in 20/430 (4.6%) and 120/524 (22.9%) in OPW and SW respectively. Over 98% of samples produced a beta-globin signal, indicating adequately collected samples. Human papilloma virus typing probes detected HPV16 or 18 in 14% and 26% of the positive samples from OPW and SW respectively. HPV31, 33, 35 or 39 were detected in 19% and 12% and HPV45, 51 or 52 in 9.5% and 4% of positive OPW and SW patients respectively. Low risk HPV6 or 11 were detected in 1% and 4.9% of OPW and SW respectively. There was a significantly higher HPV prevalence in Thai SW than OPW, with the majority (21%) of positive samples containing the oncogenic HPV16 or 18 DNA. The results indicate that PCR could serve as a rapid and easy method for identification of women who require more frequent screening for cervical cancer.

Does human papillomavirus play a role in the development of bladder transitional cell carcinoma? A comparison of PCR and immunohistochemical analysis

Aim: To investigate the role of human papillomavirus (HPV) in the development of bladder transitional cell carcinoma (TCC). Methods: Seventy eight paraffin wax embedded TCC samples were tested for the...

Coxsackie virus B types were discriminated by RT-PCR

To develop a method for detection of coxsackie B virus type 1-6 by RT-PCR. A pair of primers were designed to amplify all types of coxsackie B virus 1-6 efficiently. The PCR product was hybridized in micro-wells in which 6 type specific oligonucleotide probes had been coated respectively, colorimetric detection was performed to discriminate the types of coxsackie B virus. This method was shown to be concordant with the IgM ELISA, 71.7% of anti-coxsackie B positive cases could be detected by RT-PCR. The RT-PCR method can type coxsackie B virus efficiently and provides a tool for clinical diagnosis and epidemiological investigation.

Prognostic significance of lymph node variables and human papillomavirus DNA in invasive vulvar carcinoma

Objective. The present study investigates the influence of lymph node pathological features and HPV DNA status on the prognosis of vulvar invasive tumors. Methods. This study includes 184 consecutive cases of primary invasive squamous cell carcinoma of the vulva treated by radical surgery from 1975 to 1992, in São Paulo, Brazil. Clinical follow-up data was collected from patient files and hematoxilin–eosin sections were reviewed. HPV detection and typing was done by polymerase chain reaction (PCR), using specific and generic primers, followed by dot blot hybridization (DBH) with type-specific oligonucleotide probes for 19 HPV types. Age-adjusted Kaplan–Meier survival curves and Cox proportional hazards models were used to analyze the cancer risk associations for all DNA and pathology-related variables. Results. Among 161 cases tested by PCR, 38 (23.6%) were positive for high-risk HPV types. Regional lymph nodes of 43 cases, including all those of HPV-positive tumors and a sample of the ones removed from patients with HPV negative tumors, were evaluated by the same method. HPV DNA was found in the lymph nodes of 10 cases. In every case, at least one lymph node was metastatic and the HPV detected in the lymph nodes were of the same type as those found in the primary tumor in all cases. Multivariate analysis including age, race, pattern of invasion, tumor thickness, inflammatory reaction, surgical margins, number of node metastases, presence of extracapsular growth, depth of invasion, and presence of high-risk HPV DNA was performed. Following automated selections of this model, node variables important for prognosis that remained were number of node metastases and presence of extracapsular growth. Conclusions. Patients with four or more node metastases associated with extracapsular spread were 5.6 (95%CI: 2.3–13.1) times more likely to die from cancer and 10.0 (95%CI: 4.0–24.9) times more likely to have a recurrence than patients without metastases. The HPV status in the tumor was not important as a prognostic factor.

Contamination of environmental surfaces by genital human papillomaviruses

Objective: To investigate contamination of environmental surfaces with human papillomaviruses (HPV) DNA in two genitourinary medicine (GUM) clinics and in an on-site staff leisure and fitness centre. Methods: Samples were...

GP5+/6+ PCR followed by reverse line blot analysis enables rapid and high-throughput identification of human papillomavirus genotypes.

In this study, we developed a simple and fast typing procedure for 37 mucosotropic human papillomavirus (HPV) types using a nonradioactive reverse line blotting (RLB) procedure for general primer (GP5+/6+) PCR products. This system has the advantages not only that in a simple format, up to 42 PCR products can be simultaneously typed per membrane per day, but also that after stripping, the membranes can be easily rehybridized at least 15 times without a loss of signal. RLB appeared highly specific, and its sensitivity was identical to that of conventional typing performed with type-specific oligonucleotide probes in an enzyme immunoassay (EIA). The performance of RLB typing was evaluated with samples of HPV-positive cervical scrapings (n = 196) and biopsies of cervical premalignant lesions (n = 100). The distribution of HPV genotypes detected in these samples was in line with the distribution expected on the basis of literature data. In addition, RLB and EIA typing procedures were compared for the typing of high-risk HPV types in GP5+/6+ PCR products of 210 cervical scrapings from high-risk HPV-positive women who participated in a population-based screening program. The typing procedures had an excellent overall agreement rate of 96.5% (kappa value, 0.77). RLB was successful in detecting multiple HPV infections as well as single infections. In conclusion, the GP5+/6+ PCR-RLB procedure appeared to be a reliable and simple approach that may be of great value for large epidemiological studies, population-based cervical cancer screening programs, and vaccination trials that require high-throughput HPV typing.

Human papillomavirus genotype spectrum in Czech women: correlation of HPV DNA presence with antibodies against HPV-16, 18, and 33 virus-like particles.

Because the biological spectrum of human papillomavirus (HPV) genotypes present in cervical cancer lesions varies according to the geographical region studied, and because little genotype information is available for Central and Eastern European countries, we studied the endemic HPV-genotype spectrum in cervical samples collected from women visiting gynaecological departments of selected hospitals in the Czech Republic. In a series of 389 samples, 171 (44.0%) were positive for HPV DNA using a consensus-primer polymerase chain reaction (PCR). Genotyping of the HPV PCR products was done using dot-blot hybridisation with type-specific oligonucleotide probes and thermocycle DNA sequencing. Twenty-two different HPV types were detected, HPV-16 being the most prevalent type irrespective of severity of the lesions (55.0%). Multiple HPV types were found in 16.4% of our HPV-DNA-positive samples. The prevalence of HPV infection was 23.0% in women with normal findings and 59.4% in patients with cervical neoplasia, and increased significantly with the severity of the disease: 52.9% in low-grade lesions, 58.0% in high-grade lesions, and 73.5% in cervical carcinomas (P for trend < .00001). In the sera of 191 subjects, 89 with normal findings and 102 with different forms of cervical neoplasia, the prevalence of HPV-specific IgG antibodies was tested by an enzyme-linked immunosorbent assay (ELISA) using virus-like particles (VLPs) of HPV-16, -18, and -33. Antibodies were significantly more prevalent in HPV-DNA-positive than in HPV-DNA-negative women and there was no association with age. In agreement with the results of HPV genotyping, antibodies reactive with HPV-16 VLPs were the most frequent and, moreover, their prevalence increased with the cervical lesion severity. About half of the subjects with smears in which either HPV-16 or HPV-33 DNA had been detected possessed antibodies reactive with homotypic VLPs. With HPV-18-DNA-positive subjects, however, fewer than 25% displayed homotypic antibodies. In general, subjects older than 30 years of age had antibodies reactive to HPV-specific VLPs more often than subjects younger than 30 years of age. In women with benign findings, the seropositivity to HPV-16, -18, and -33 VLPs increased with age, whereas in women with cervical neoplasia the seropositivity decreased with age.

High-risk human papillomavirus types and squamous cell carcinoma in patients with respiratory papillomas

Respiratory papillomas (RPs) are benign, virally induced tumors of the larynx and respiratory epithelium that may obstruct the airway and tend to recur frequently. RPs are thought to be the result of infection with the human papillomaviruses (HPVs) types 6 and 11. We surveyed archival RP specimens to determine whether there were correlations of HPV type with patient characteristics or clinical course. Paraffin-embedded papilloma specimens of 45 different patients were analyzed. We assessed HPV types using the polymerase chain reaction with E6 consensus primers, hybrid capture assays (high or low risk), and dot blot hybridization of generic E6 PCR products with E6 type-specific oligonucleotide probes. The presence and type of HPV were correlated with patient data from a retrospective chart review. We found that RPs may have either low- or high-risk HPV types and some contain multiple HPV types. Respiratory infection with high-risk HPV apparently introduces a long-term risk of squamous cell carcinoma development, even in the absence of conventional cofactors. Low-risk HPV infection may also act in association with these cofactors to promote carcinogenesis. Our data also show a racial imbalance in RP that may indicate a difference in genetic resistance and/or susceptibility to HPV infection and the development of RP. (Otolaryngol Head Neck Surg 1999;120:698-705.)

P53 inactivation in chewing tobacco-induced oral cancers and leukoplakias from India

The inactivation of p53 tumour suppressor gene vis-á-vis point mutation, overexpression and degradation due to Human Papilloma virus (HPV) 16/18 infection, was examined in chewing tobacco-associated oral cancers and oral leukoplakias from India. The analysis of mutations was assessed by polymerase chain reaction (PCR) with single strand conformation polymorphism (PCR-SSCP) of exons 5-9 on DNA from 83 oral cancer cases, and the mutations confirmed by direct nucleotide sequencing of the PCR products. p53 protein expression was evaluated by immunohistochemical analysis on paraffin-embedded sections of 62 representative oral cancer biopsies and 22 leukoplakias, using p53-specific monoclonal antibody DO-7. The presence of HPV16/18 was detected in the 83 oral cancer cases by PCR analysis using HPV L1 consensus sequences, followed by Southern hybridization with type-specific oligonucleotide probes. Forty-six per cent (38/83) of oral cancer tumours showed p53 alterations, with 17% (14/83) showing point mutations, 37% (23/62) with overexpression and 25% (21/83) with presence of HPV16 wherein the E6 HPV16 protein degrades p53. HPV18 was not detected in any of the samples. Ninety-two per cent concordance was observed between missense point mutations and overexpression of p53 protein. A significant correlation was not observed between p53 alterations in oral cancer and clinico-pathological profile of the patients. Twenty-seven per cent (6/22) of oral leukoplakias showed p53 overexpression. The overall p53 alterations in oral cancer tissues and oral lesions are comparable to data from the oral cancers reported in the Western countries with smoking and alcohol-associated oral cancers, and suggest a critical role for p53 gene in a significant proportion of oral cancers from India. The overexpression of p53 protein in leukoplakias may serve as a valuable biomarker for identifying individuals at high risk of transformation to malignant phenotype.

Detection of HPV-16 genome in human oral cancers and potentially malignant lesions from India.

The presence of high risk human papilloma virus (HPV) 16 and 18 was examined in 100 oral cancer patients of Indian descent, 80 patients with potentially malignant oral lesions and corresponding clinically normal mucosa from 48 of these patients. Additionally, presence of HPV-33, -6 and -11 was also studied in 86 oral cancers, 50 potentially malignant oral lesions and 30 corresponding normal oral mucosa. All the patients with oral cancer and oral lesions, were long term tobacco-chewers, and a majority of the patients were in Advanced Stages III and IV. The DNA samples were amplified by polymerase chain reaction (PCR) using HPV L1 consensus primers. Typing of HPV was performed by Southern hybridization analysis of the PCR products using HPV-16, -18, -33, -6 and -11 type specific oligonucleotide probes. HPV-16 was detected in 15 out of 100 (15%) oral tumours, 27 out of 80 (34%) potentially malignant lesions and 15 out of 48 (31%) of the corresponding normal mucosa in the patients with oral lesions. HPV-18 was not detected in any of the oral cancers, oral lesions and normal mucosa. HPV-33 and the low-risk HPV-6 and -11 were also not detected in the oral cancers, oral lesions and corresponding normal mucosa. A significantly higher prevalence of HPV-16 was observed in oral lesions (27 out of 80, 34%) as compared to oral cancers (15 out of 100, 15%). The observed difference of 19% (95% confidence interval [CI]: 6%, 31%), between these two proportions was statistically significant at the 5% level of significance. Our data indicates that HPV-16 may play a direct role in a certain proportion of oral cancers; whereas in a subpopulation of oral cancers HPV-16 infection may be vital in the early events associated with development of potentially malignant oral lesions, and the presence of the virus not essential in the progression of the oral lesion to frank malignancy.