Exosome-Transmitted miR-224-5p Promotes Colorectal Cancer Cell Proliferation via Targeting ULK2 in p53-Dependent Manner

Objective To investigate the role and molecular mechanism of exosomal miR-224-5p in colorectal cancer(CRC).Methods The miR-224-5p expression in CRC patient tissues and cell-derived exosomes was measured by laser capture microdissection and qRT-PCR,respectively.Dual-luciferase reporter gene assay was used to determine the target gene of miR-224-5p.The protein expressions of p53 and unc-51 like kinase 2(ULK2)in CRC cells were detected by western blot.Flow cytometry was used to detect cell cycle and apoptosis.Cell proliferation was measured by CCK8 and EdU assay.Results The miR-224-5p expression was upregulated in CRC tissues and increased progressively with the rise of CRC stage.CRC cells secreted extracellular miR-224-5p mainly in an exosome-dependent manner,and then miR-224-5p could be transferred to surrounding tumor cells to regulate cell proliferation in the form of autocrine or paracrine.Moreover,ULK2 was characterized as a direct target of miR-224-5p and was downregulated in CRC tissues.Interestingly,ULK2 inhibited CRC cell proliferation in a p53-dependent manner.Furthermore,exosome-derived miR-224-5p partially reversed the proliferation regulation of ULK2 on CRC cells.Conclusion Our findings demonstrate that exosome-transmitted miR-224-5p promotes p53-dependent cell proliferation by targeting ULK2 in CRC,which may offer promising targets for CRC prevention and therapy.

BOPl Silencing Suppresses Gastric Cancer Proliferation through p53 Modulation

Block of proliferation 1(BOP1)is a key protein involved in ribosome maturation and affects cancer progression.However,its role in gastric cancer(GC)remains unknown.This study aimed to explore the expression of BOPI in GC and its potential mechanisms in regulating GC growth,and the relationship between BOP1 level in cancer tissues and survival was also analyzed.The expression of BOPI was examined by immunohistochemistry(IHC)in a cohort containing 387 patients with primary GC.Cultured GC cells were treated by siRNA to knock down the BOP1 expression,and examined by CCK-8 assay and plate clone formation to assess cell proliferation in vitro.Apoptotic rate of cultured GC cells was detected by flow cytometry with double staining of AnnxinV/PI.The xenografted mouse model was used to assess GC cell proliferation in vivo.Western blot and IHC were also performed to detect the expression levels of BOP1,p53 and p21.Patients with higher level of BOP1 in cancer tissues had significantly poorer survival.BOP1 silencing signifcantly suppressed GC cell proliferation both in vitro and in vivo.It blocked cell cycle at G0/G1 phase and led to apoptosis of GC cells via upregulating p53 and p21.BOP1 silencing-induced suppression of cell proliferation was partly reversed by pifithrin-a,(a p53 inhibitor).Our study dermonstrated that BOP1 up-regulation may be a hallmark of GC and it may regulate proliferation of GC cells by activating p53.BOP1 might be considered a novel biomarker of GC proliferation,and could be a potential indicator of prognosis of GC patients.BOP1 might also be a potential target for the treatment of GC patients if further researched.

Long-term omeprazole and esomeprazole treatment does not significantly increase gastric epithelial cell proliferation and epithelial growth factor receptor expression and has no effect on apoptosis and p53 expression

AIM： To study the effect of proton pump inhibitor （PPI） treatment on patients with reflux esophagitis and its in vivo effect on apoptosis, p53- and epidermal growth factor receptor （EGFR） expression. METHODS： After informed consent was obtained, gastric biopsies of the antrum were taken from patients with reflux oesophagitis prior to and after 6 mo of 20 mg omeprazole （n = 24） or 40 mg esomeprazole （n = 22） therapy. Patients did not take any other medications known to affect the gastric mucosa. All patients were Helicobacter pylori negative as confirmed by rapid urease test and histology, respectively. Cell proliferation, apoptosis, EGFR, and p53 expression were measured by immunohistochemical techniques. At least 600 glandular epithelial cells were encountered and results were expressed as percentage of total cells counted. Was considered statistically significant. RESULTS： Although there was a trend towards increase of cell proliferation and EGFR expression both in omeprazole and esomeprazole treated group, the difference was not statistically significant. Neither apoptosis nor p53 expression was affected. CONCLUSION： Long-term PPI treatment does not significantly increase gastric epithelial cell proliferation and EGFR expression and has no effect on apoptosis and p53 expression.

The effect of C-terminal fragment of JNK2 on the stability of p53 and cell proliferation

The basal activity of JNK is low in normal growing cells and inactivated JNK targets p53 for ubiquitination. To elucidate if the C-terminal part of JNK is responsible for its binding to p53, the low background tet-off inducible NIH3T3 cell line was selected by luciferase reporter gene and a double stable C-JNK Aa (203-424) cell line was established. After withdrawing tetracycline, the C-JNK fragment expression was induced and cell growth was dramati- cally inhibited 24 h later. However, the expresion of p53 was found to be increased after the induction of C-JNK fragment, evaluated by transfecting p21waf-luciferase reporter genes. Our further studies showed that C-JNK fragment could form complex with p53 both in vivo and in vitro. Induction of C-JNK fragment in vivo can increase p53 stability by inhibiting p53 ubiquitination.

Study on the correlation between CT appearance and expression of p53 protein in peripheral lung cancer

Objective: To investigatethecorrelationbetweenCT appearanceandexpressionof p53proteininperipheral lungcancer.Methods:Theexpressionof p53proteinwasexaminedby meansof SP immunohistochemicaltechniquein32casesof peripherallungcancer.TheircorrelationwiththepreoperativeCT appearancewas analyzedretrospectively.Results:Theexpressionof p53proteinwascorrelatedwithtumorsize,lobulation,cavitation,pleuralindentationandme-diastinallymphnodeenlargement,butnotwithspiculation.Tumorwithmaximumdiametergreaterthan3cm or withthe presenceof lobulation,cavitation,pleuralindentationor mediastinallymphnodelarger than10mminshortaxishada rel-ativelyhigherlevelof p53expression.Conclusion:CT signsof peripheral lungcancersarevaluablenotonlyindifferen-tiatingcancersfrombenignlesions,as knownbefore,butalsoinprovidingfurtherinformationforthemalignantpotential of cancers.Largertumorsize,lobulation,cavitation,pleuralindentation,andmediastinallymphnodeenlargementmaybe likelyrelatedto a higherdegreeof malignantpotentialandmoreaggressivetumorbehavior.

EFFECTS OF p53 OVEREXPRESSION ON NEOPLASTIC CELL PROLIFERATION AND APOPTOSIS IN THYMIC CARCINOMA

Objective: To investigate p53 overexpression and its correlation with neoplastic cell proliferation and apoptosis in 20 thymic carcinomas. Methods: 20 surgical samples of thymic carcinoma were collected randomly during the past 15 years in the Guangzhou area. Immunohistochemical staining was performed using LSAB method with anti-p53 monoclonal antibody (DO-7) and proliferating cell nuclear antigen (clone PC 10) as primary antibodies. The p53 index was indicated by the number of p53 positive cells among 100 carcinoma cells. More than 25 percentage of p53 positive cells found in tissue sections was recognized as p53 overexpression. Carcinoma cell proliferation activity was assayed by PCNA index (PI), and apoptosis degree was evaluated by TUNEL (TdT-mediated dUTP-X nick end labeling) index (TI) using Boehringer MannheimIn Situ Death Detection Kit. Results: P53 positive cells could be found in vast majority of thymic carcinomas (19/20) and the overexpression rate reached 35% (7/20). The median PI (40%) of 7 cases with p53 overexpression was higher than that (31%) of 13 cases without p53 overexpression, but there was no statistical significance that existed between these two data (P>0.05). The median TI (0.5/HPF) of 7 p53 overexpression cases was much lower than that (4.5/HPF) of 13 non-overexpression cases, and there was a significant difference statistically (P<0.05). Conclusion: p53 expression was a frequent finding in thymic carcinoma cells, and the p53 overexpression which might represent p53 inactivation or gene mutation was often involved in thymic carcinogenesis. The median PCNA index of p53 overexpression group was higher than that of non-overexpression group though there existed no statistical difference. This indicates that the inhibiting function of p53 on cell proliferation seemed lost in p53 overexpressed thymic carcinomas. It is worthy to be specially mentioned that the inducing function of p53 on cell apoptosis was markedly lost in p53 overexpressed thymic carcinomas. Taken together, the overexpressed p53 that could represent aberrant p53 protein had not only lost its proliferation-inhibiting but also its apoptosis-inducing function in thymic carcinomas which might play an important role in thymic carcinogenesis.

Expression of Survivin, p53 and its relationship with apoptosis, proliferation in hepatocellular carcinoma(HCC)

Objective：To investigate the expression of Survivin p53 and its relationship with apoptosis, proliferation in hepatocellular carcinoma （HCC）. Methods：The expression of Survivin, p53 and the proliferation of tumor cells marked by proliferation cell nuclear antigen （PCNA） in 42 cases of HCC were assessed by immunohistochemical method. TUNEL was used to detect apoptosis. Results：Survivin protein was expressed in 30 of 42 cases of HCC（71.4%） and in 4 of 34 cases of adjacent cirrhosis tissues（11.8%）. Expression of Survivin protein was negative in 10 cases of normal tissues. Survivin protein positive expression rate in HCC was significantly higher than adjacent cirrhosis tissues and normal tissues（P 〈 0.001）. The increased Survivin protein expression in cancer was significantly associated with histological grade（P = 0.003）, p53 protein（P = 0.013）, survival time（P 〈 0.05） and the ratio of proliferative index to apoptotic index（P〈 0.01）, but was not significantly correlated with age, sex, clinical stage, tumor size, metastasis, AFP, HBs-Ag（P 〉 0.05）. Conclusion：There is a marked increased expression of Survivin in HCC, which may play an important role in breaking the balance of proliferation and apoptosis of HCC cells. The correlation between Survivin and p53 expression in HCC indicates that cooperation between Survivin and p53 plays a certain role in occurrence and/or development of HCC.

Changes of p53 protein blood level in esophageal cancer patients and normal subjects from a high incidence area in Henan,China

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Relationship between therapeutic efficacy of arterial infusion chemotherapy and expression of P-glycoprotein and p53 protein in advanced hepatocellular carcinoma

AIM： To investigate the relationship between the chemotherapeutic drug efficacy and the expression of P-glycoprotein （PGP） and p53 protein in advanced hepatocellular carcinoma （HCC）. METHODS： The study was conducted on 41 patients with advanced HCC who were treated by repeated arterial infusion chemotherapy. Biopsy specimens from the tumor were collected before the start of treatment in all the patients, and the specimens were stored frozen until immunohistochemical staining, which was performed after the start of treatment, to detect PGP and p53 protein expressions. Twenty of the fortyone patients were treated with an anthracycline drug （epirubicin hydrochloride; anthracycline group）, and the remaining 21 were treated with a non-anthracycline drug （mitoxantrone hydrochloride in 11 patients and carboplatin in 10 patients; non-anthracycline group）. The relationship between the chemotherapeutic efficacy and the results of immunostaining were compared between the two groups. RESULTS： Before the start of the treatment, PGPpositive rate was 90.2% （strongly-positive, 36.6%） and p53 protein-positive rate was 34.1% （strongly-positive, 19.5%）. In the anthracycline group, the response rate was 40.0%. The number of patients showing poor response to the treatment was significantly larger in the patients with strongly positive PGP expression （P= 0.005）, and their prognoses were poor （P= 0.001）. in the nonanthracycline group, the response rate was 42.9%,and there was no significant relationship between the chemotherapeutic drug efficacy and the PGP or p53 protein expression. When only the data from the 11 patients treated with anthraquinone drug, mitoxantrone, were analyzed, however, the number of patients who showed poor response to treatment was significantly higher among the p53-positive patients （P= 0.012）, irrespective of the survival outcome. CONCLUSION： The chemotherapeutic efficacy with an anthracycline drug for advanced HCC can be predicted by immunohistochemical analysis of PGP expression. Similarly, immunostaining to evaluate p53 protein may be useful to predict the response in patients treated with an anthraquinone drug.

The Relationship of Expression of bcl-2, p53, and Proliferating Cell Nuclear Antigen (PCNA) to Cell Proliferation and Apoptosis in Renal Cell Carcinoma

To investigate the relationship of bcl-2, p53, proliferating cell nuclear antigen (PCNA) to cell proliferation, apoptosis and pathological parameters, the patterns of cell growth and turnover in renal cell carcinoma (RCC), formalin-fixed and paraffin-embedded tissue blocks from 34 patients with RCC were examined. Cell proliferation activity was detected by PCNA immunostaining and the proliferation index (PI) was expressed as a percentage of the PCNA-positive cells in the tumor cells. Apoptosis was detected by terminal deoxy- nucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and the apoptotic index (AI) was expressed as a percentage of the TUNEL-positive cells in the tumor cells. Expressions of bcl-2 and p53 were assessed immunohistochemically. Our results showed that the PI ranged from 6.0 % to 24.0 % (median 12.3 %) and the AI from 2.0 % to 8.0 % (median 5.4 %) in RCC. The expression of the bcl-2 protein was demonstrated in 15 cases (44.1 %); the expression of the p53 protein, however, was seen in only 3 case. bcl-2 positivity was not associated with PI or AI or any pathological parameters. There were close associations between PI and tumor grade and stage, and a significant relationship between AI and the tumor grade of RCC. Our study suggests that bcl-2 positivity was not associated with PI or AI or any pathological parameters. There are close associations between PI and AI and tumor grade and stage of RCC. Active cell proliferation may be accompanied by frequent apoptosis in RCC.

Clinical significance of immunohistochemica study of P53 protein in colorectal carcinoma

AIMS To determine the clinical significance of P53 protein ex-pression in colorectal carcinoma.METHODS The expression of P53 protein in 92 colorectal car-cinomas was examined using the monoclonal antibody PAb 1801.Correlation between P53 protein expression and prognosis in col-orectal carcinoma was analyzed using log-rank test.RESULTS The frequency of P53 protein expression was 57.61%,corresponding with Dukes’ staging.Analysis of survivordata demonstrated that the survival rate of colorectal carcinomawith positive P53 protein group was lower than that of negativeP53 protein group.CONCLUSIONS We conclude that the expression of P53 pro-tein is correlated with poor prognosis in colorectal carcinoma.

Saikosaponin D inhibits proliferation and induces apoptosis via C/EBPβ-p53 signal pathway in human hepatoma HepG2 cells

Objective To investigate the anticancer effects and detailed mechanisms of Saikosaponin D(SSD)in human hepatoma HepG2 cells.Methods Cell proliferation and apoptosis were tested by MTT assay and Annexin-V/PI assay respectively.The expressions of CCAAT enhancer binding protein β(C/EBPβ)and p53 were detected by RT-PCR and Western blotting.Results SSD inhibited cell proliferation in a dose-dependent manner and induced apoptosis at the concentration of 5.0 mg/L.SSD significantly increased the mRNA and protein levels of C/EBPβ and p53 in a dose-dependent manner.Conclusion SSD exerts its anticancer effect by inhibiting cell proliferation and inducing apoptosis partly through C/EBPβ-p53 signal pathway in HepG2 cells.

EXPRESSION OF P53 PROTEIN AND PROLIFERATING CELL NUCLEAR ANTIGEN IN HUMAN GESTATION TROPHOBLASTIC DISEASE

To study the relationship between p53 protein, proliferating cell nuclear antigen (PCNA) expression and benign or malignant gestational trophoblastic disease (MGTD). Methods: The histotomic sections of 48 patients with gestational trophoblastic disease and 24 patients of normal chorionic villi were stained using immunohistochemistry. The monoclonal antibodies were used to determine p53 protein and PCNA. Results: The frequency of p53 and PCNA positive expression were significantly different among the chorionic villi of normal pregnancy, hydratidiform mole (HM) and MGTD. But neither p53 nor PCNA has any relation with the clinical staging or metastasis of MGTD. Conclusion: Both P53 and PCNA are valuable in diagnosis of human gestational trophoblastic disease.

Effect of Electroacupuncture on Expression of p53 Protein in Cerebral Cortex of Rats with Global Cerebral Ischemia/Reperfusion Injury

Objective: To observe the effect of electroacupuncture (EA) on expression of p53 protein in cerebral cortex of senile rats with global cerebral ischemia/reperfusion (IR) injury and to explore its mechanism. Methods: The cerebral IR injury rat model was established referring to Pulsinelli 4-vessel occlusion method. Thirty-six SD rats were randomly and evenly divided into the control group, the IR group and the IR plus EA (IR-EA) group. The animals in the control group were subjected to electrocauterization of vertebral arteries in bilateral flank orifice alone with the general carotid arteries unoccluded. To rats in the IR-EA group, immediately and 24h, 48h, 72h after cerebral IR, EA treatment on bilateral acupoint 'Zusanli' (ST36) was applied once a day, lasting for 60 minutes. After the final treatment, all the rats were sacrificed and their brains were taken to examine p53 protein expression by the immunohistochemical method. Results: Cells with positive p53 immunoreactivity in the cerebral cortex of rats in the IR group was significantly higher than that in the control group ( P<0. 05), while that in the IR-EA group was significantly lower than that in the IR group ( P<0. 05). Conclusion: EA could remarkably reduce expression of p53 protein in the cerebral cortex of senile rats with global cerebral IR injury, which might be one of the means for EA to inhibit neuronal ap-optosis after cerebral IR injury.

Correlation and Expression of COX-2 and P53 Protein in Basal Cell Carcinoma of Eyelid

The correlation between the expression of COX-2 and p53 protein in basal cell carcinoma （BCC） of eyelid and apoptosis was investigated. Specimens of BCC were collected from 40 cases （aged 28-68 y） at the Department of Pathology, Renmin Hospital of Wuhan University, and Department of Pathology, Zhongnan Hospital of Wuhan University during from 1999 to 2006. Five specimens of paracancerous tissues served as control group. Immunohistochemical staining was performed to detect the expression of COX-2 and p53 in the tissues. The average absorbance （A） and the average positive area rate of COX-2 and p53 protein were measured by image analysis. The positive area rate of COX-2 and p53 protein was analyzed by linear correlation analysis. It was found that COX-2 and p53 proteins were highly expressed in BCC of eyelid, and weakly expressed in paracancerous tissues. Image analysis revealed that the expression of COX-2 and p53 proteins in BCC of eyelid was sig- nificantly higher than that in paracancerous tissues （P〈0.01）. Spearman rank correlation analysis demonstrated a positive correlation between the expression of COX-2 and p53 （r=0.113, P=0.421）. It was concluded that COX-2 can increase the expression of p53 protein, therefore suppressing apoptosis.

Effects of nanometer particles and water decoction of the Chinese medicine mixture of pinellia ternate and scorpion on P53 protein contents and apoptosis in the cerebral cortex and hippocampus of epileptic rats

BACKGROUND： Water decoction of the Chinese traditional medicine mixture of pinellia ternate and scorpion is an effective treatment for epilepsy. OBJECTIVE： To compare nanometer particles and effects of water decoction of Chinese traditional medicine mixture on P53 protein levels and apoptosis in the cerebral cortex and hippocampus of epileptic rats. DESIGN, TIME AND SETTING： This randomized, controlled molecular biology study was performed at the Key Laboratory of Child Neural Rehabilitation of Jiamusi University from October to December 2007. MATERIALS： Forty healthy male Wistar rats were used in this study. Convulsion rat models were established by intraperitoneal infusion of 35 mg/kg pentylenetetrazol, once a day, for 28 successive days. The Chinese traditional medicine mixture, comprising pinellia ternate, scorpion, centipede, bupleurum, peach pit and glycyrrhiza, was purchased from Beijing Tongrentang, China. The mixture was made into nanometer particles and water decoction. The apoptosis determination kit and P53 immunohistochemistry kit were bought from Boster, China. METHODS： Forty Wistar rats were randomly divided into four groups of ten rats per group, control, nanometer particle, water decoction and epileptic model groups. Rats in the nanometer particle and water decoction groups were respectively treated with 300 mg/kg Chinese herb nanometer particle suspension and water decoction by gavage, once a day, for 28 days. Rats in the epileptic model group were fed an equal volume of saline by gavage. Rats in the control group were only administered with the same volume of saline by gavage. MAIN OUTCOME MEASURES： Terminal deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling （TUNEL） and immunohistochemistry were used to respectively detect neuronal apoptosis and P53 protein expression in the rat brain cortex and hippocampus at 28 days following administration. RESULTS： The number of apoptotic neurons was lower in the nanometer particle and water decoction groups compared with the epileptic model group. The number of apoptotic cells and P53 protein expression in the rat cerebral cortex and hippocampus was greater in the epileptic model group compared with the control group （P 〈 0.05）, but lower in the nanometer particle and water decoction groups compared with the epileptic model group （P 〈 0.05）, and lower in the nanometer particle group compared with the water decoction group （P 〈 0.05）. CONCLUSION： Chinese traditional medicine mixture decreases neuronal apoptosis and P53 protein expression in epileptic rats. The effect of nanometer particles is significant compared with water decoction.

THE STUDY ON RELATIONSHIP BETWEEN CIGARETTE SMOKING AND THE p53 PROTEIN AND P21 PROTEIN EXPRESSION IN NON-SMALL LUNG CANCER

This paper discusses the relationship between cigarette smoking and the p53 protein and P21 protein expression by the immunohistochemical analysis in 93 cases with lung cancer in which squamous cell carcinoma accounted for 45 cases, adenocarcinoma 48 cases. The results showed that positive proportion of p53 protein expression was 74.20% (28 of 37 squamous cell carcinoma, 21 of 30 adenocarcinomas) in cigarette smoking group with lung cancers, and 38.46% (3 of 8 squamous cell carcinoma, 7 of 18 adenocarcinomas) in nonsmoking group with lung cancers. The difference was statistically significant. Odds ratio was 4.14 and confidence limits for OR was 1.42-12.52. A dose-related presents in the p53 protein expression for the smoking amount and smoking years. The positive proportion of P21 protein expression was 79.31% (21 of 28 squamous cell carcinoma, 25 of 30 adenocarcinomas) in cigarette smoking group with lung cancers, and 82.75% (10 of 11 squamous, 14 of 18 adenocarcinomas) in nonsmoking group with lung cancers, the difference was not statistically significant. But their positive proportion of P21 protein expression were very high in both groups. It was indicated that no relationship between cigarette smoking and the P21 protein expression. We suggest that the p53 gene could be a common target of tobacco-associated carcinogenesis in lung cancer.

Human papillomavirus and p53 protein immunoreactivity in condylomata acuminatum and squamous cell carcinoma of penis

Aim: To determine the immunoreactive pattern of human papillomavirus (HPV) antigen and p53 protein in condylo-mata acuminatum (CA) and squamous cell carcinoma (SCC) of penis. Methods: Immunohistochemistry for HPVand p53 were performed in 40 specimens of formalin fixed, paraffin embedded tissues using a polyclonal (rabbit) anti-body against HPV and a monoclonal (mouse) antibody against human p53 protein. Twenty one cases of CA and nine-teen cases of SCC were examined. Results: HPV antigen was detected in all 21 CA and 2 penile SCC. p53 proteinoverexpression was observed in 12 of 19 (63%) SCC in which 6 cases were strong positive. Five of 21 CA (24%)showed low-grade p53 protein overexpression. Conclusion; CA is related to HPV infection and some cases showp53 protein low-grade overexpression. In contrast, p53 protein overexpression is common in penile SCC, which is sel-dom related to HPV infection. (Asian J Androl 2001 Mar; 3: 75-77)

EXPRESSION OF p53 PROTEIN IN CANCERS OF SMALL INTESTINE AND ITS RELATIONSHIP TO CLINICAL COURSE AND PROGNOSIS

In order to study the relationship of p53 gene mutation with the occurrence and prognosis of cancer of small intestine, expression of p53 protein was immunohistochemically examined. The results showed that p53 protein expression was high in 75% of small intestine cancer, and positive in 21.1% of the tissues close to cancer. In 7 cases of small intestinal adenoma, only one was immunoreactive. Sixteen samples of normal tissue of the intestine didn't show expression of p53protein. The study also found that the degree of p53protein expression was significantly correlated with that of tumor cell differentiation, invasion, metastasis and prognosis.

Association between HPV16/18 Infection and Expression of P53 protein in Laryngeal Papillomas

To understand the relationship between expression of P53 protein and HPV16/18 infection in laryngeal papillomas, PCR and immunohistochemical tech-niques were used to examine the paraffin-embedded tissue samples of laryngeal pa-pillomas from 35 subjects. HPV 16/18-DNA was found in 24 cases of laryngeal papillomas (68. 8 %). Overexpression of P53 protein was detected in 19 cases (54. 3 % ). Both HPV16/18-DNA and overexpression of P53 protein were demon-strated in 12 cases of laryngeal papillomas (34. 3 % ). Our results suggest that HPV16/l8 infection and P53 gene mutation are associated with pathogenesis of la-ryngeal papillomas. The relation between HPV infection and P53 mutation in tis-sues of laryngeal papillomas remains to be clarified.