Downregulation of iASPP Expression Suppresses Proliferation, Invasion and Increases Chemosensitivity to Paclitaxel of Head and Neck Squamous Cell Carcinoma In Vitro

Objective Our previous study has revealed that iASPP is elevated in human head and neck squamous cell carcinoma(HNSCC)and iASPP overexpression signifcantly correlates with tumor malignant progression and poor survival of HNSCC.This study investigated the function of iASPP playing in proliferation and invasion of HNSCC in vitro.Methods HNSCC cell line Tu686 transfected with Lentiviral vector-mediated iASPP-specific shRNA and control shRNA were named the shRNA-iASPP group and shRNA-NC group,respectively.The non-infected Tu686 cells were named the CON group.CCK-8 assay,flow cytometry,transwell invasion assay were performed to detect the effects of iASPP inhibition in vitro.Results Our results demonstrated that the proliferation of shRNA-iASPP cells at the time of 72 h(F=32.459,P=0.000),96 h(F=51.407,P=0.000),120 h(F=35.125,P=0.000)post-transfection,was significantly lower than that of shRNANC cells and CON cells.The apoptosis ratio of shRNA-iASPP cells was 9.42%±0.39%(F=299.490,P=0.000),which was significantly higher than that of CON cells(2.80%±0.42%)and shRNA-NC cells(3.18%±0.28%).The percentage of shRNA-iASPP cells in G0/G1 phase was 74.65%±1.09%(F=388.901,P=0.000),which was strikingly increased,compared with that of CON cells(55.19%±1.02%)and shRNA-NC cells(54.62%±0.88%).The number of invading cells was 56±4 in the shRNA-iASPP group(F=84.965,P=0.000),which decreased significantly,compared with the CON group(111±3)and the shRNA-NC group(105±8).The survival rate of shRNA-iASPP cells administrated with paclitaxel was highly decreased,compared with CON cells and shRNA-NC cells(F=634.841,P=0.000).Conclusion These results suggest iASPP may play an important role in progression and aggressive behavior of HNSCC and may be an efficient chemotherapeutic target for the treatment of HNSCC.

Predictive value of MTT assay as an in vitro chemosensitivity testing for gastric cancer:One institution's experience

AIM:To investigate the predictive clinical value of in vitro 3-(4,5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay for directing chemosensitivity in patients with gastric cancer. METHODS:Results of a total of 353 consecutive patients with gastric cancer treated with MTT-directed chemotherapy or physician’s empirical chemotherapy from July 1997 to April 2003 were reviewed and analyzed retrospectively. RESULTS:The overall 5-year survival rate of MTT- sensitive group (MSG) and control group (CG) was 47.5% and 45.1%, respectively. The results of subgroup analysis with Cox proportional-hazards model were favorable for the MSG-sensitive group. However, no statistically significant difference in survival rate was observed between the two groups. CONCLUSION:Individualized chemotherapy based on in vitro MTT assay is beneficial, but needs to be confirmed by further randomized controlled trials.

Cyclin Dl antisense oligodexoyneucleotides inhibits growth and enhances chemosensitivity in gastric carcinoma cells

AIM： To examine the effects of cyclin D1 antisense oligodexoyneucleotides （ASODN） on growth and chemosensitivity of gastric carcinoma cell lines SGC7901 and its mechanism. METHODS： Phosphorothioate modified cyclin D1 ASODN was encapsulated by LipofectAMINE2000 （LF2000） and transfected into cells, the dose-effect curves and growth curves were observed. 5-FU, MTX, CDDP of different concentrations were given after transfecting cells with cyclin D1 ASODN for 24 h, the dose-effect responses were observed and IC50s were calculated. The mRNA expression of cyclin D1, thymidylate synthase （TS）, thymidine phosphorylase （TP） and dihydrofolate reductase （DHFR） was detected by reverse transcription-PCR （RTPCR） at 24 h and 48 h after transfection. RESULTS： Dose-dependent inhibitory effect was caused by cyclin D1 ASODN in SGC7901 cells. Transfecting gastric carcinoma cells with 0.2 μmol/L cyclin D1 ASODN for 24 h could inhibit growth significantly and reduce expression of cyclin D1 mRNA. Cyclin D1 ASODN could increase the chemosensitivity to 5-FU, MTX, CDDP in cells, The IC50s of different chemotherapeutic agents in ASODN plus chemotherapy groups were significantly lower than those in controls. Transfection with cyclin D1 ASODN leaded to an increase in TS and DHFR mRNA and a decrease in TP mRNA as determined by RT-PCR at 24 h, the alterations were more significant at 48 h. CONCLUSIONS： Cyclin D1 ASODN can decrease mRNA expression of cyclin D1, inhibit growth and enhance the chemosensitivity by changing the expression of enzymes related to metabolism of chemotherapeutic agents in SGC7901 gastric carcinoma cells.

Elucidation of the relationship of BNIP3 expression to gemcitabine chemosensitivity and prognosis

AIM: To evaluate the significance of BNIP3 in the pathogenesis of pancreatic cancer, we analyzed the relationship between the expression of BNIP3 and survival rate of the patients with pancreatic cancer, or chemosensitivities in pancreatic cancer cell lines, particularly for gemcitabine, the first-line anti-tumor drug for pancreatic cancer. METHODS: To compare the expression level of BNIP3 with the resistance to gemcitabine, eight pancreatic cancer cell lines were subjected to gemcitabine treatment and the quantitative real-time RT-PCR method was used to evaluate BNIP3 expression. Immunohistochemical analysis was also performed using 22 pancreatic cancer specimens to study relationship between BNIP3 expression and survival rate. RESULTS: Although no significantly positive association between BNIP3 mRNA level and gemcitabine chemosensitivity was observed, pancreatic cancer cell lines that were sensitive to gemcitabine treatment tended to show high levels of BNIP3 expression. The converse, an absence of BNIP3 expression, was not correlated with gemcitabine resistance. We further compared the BNIP3 expression profiles of resected primary pancreaticcancer specimens with the prognosis of the patients, and found a tendency of favorable prognosis and low BNIP3 expression. CONCLUSION: High levels of BNIP3 expression cannot be used as one of the predicting factors for gemcitabine chemosensitivity, and some yet to be known factors will have to fill the gap for the accurate prediction of pancreatic cancer chemosensitivity to gemcitabine. However, BNIP3 expression may have an impact on prediction of prognosis of patients with pancreatic cancer.

Low hypoxia inducible factor-1α(HIF-1α)expression in testicular germ cell tumors--a major reason for enhanced chemosensitivity?

The molecular basis for enhanced chemosensitivity of testicular germ cell tumors （GCT） has been an area of great interest, as it could potentially give us therapeutic leads in other resistant malignancies. Thus far, however, the increased sensitivity of C＆T has been variously attributed to multiple factors -- an inability to detoxify cisplatin, a lack of export pumps, an inability to repair the DNA damage, an intact apoptotic cascade and lack of p53 mutation; but a unifying underlying etiology leading to the aforementioned processes and having a translational implication has so far been elusive. Herein, we offer evidence to support a potential significant role for the previously demonstrated low hypoxia inducible factor-la （HIF-la） expression in mediating the general exquisite chemosensitivity of testicular GCT, through the aforementioned processes. This molecular mechanism based hypothesis could have a significant translational implication in platinum refractory GCT as well as other platinum resistant malignancies.

Inhibition of Girdin enhances chemosensitivity of colorectal cancer cells to oxaliplatin

AIM: To investigate the effect of Girdin knockdown on the chemosensitivity of colorectal cancer cells to oxaliplatin and the possible mechanisms involved.

Enhanced chemosensitivity of p73α gene transferred into H1299 cell line of human lung adenocarcinoma

Objective: To study the effects of transferred wild type p73α gene on the sensitivity to the chemotherapeutic agents and the growth of p53-null H1299 cells of human lung adenocarcinoma. Methods: The pcDNA3-HA-p73α plasmid was transferred into the cultured p53-null H1299 cells of human lung adenocarcinoma with the mediation of Dosper liposome; The cells resistant to G418 were selected. The expression of p73α gene in the cells was examined with Western blot. MTT assay was used to analyze the response of the transfected cells to cis-dichlorodiamine platinum (cDDP) and adriamycin (ADM). The rate of drug-induced apoptosis of the transfected cells was determined with flow cytometry and DNA fragmentation assay. The changes of the biological behaviors were observed with colony formation assay. Results: The transfected H1299 cells of human lung adenocarcinoma over-expressed p73α protein stably. MTT assay showed that the IC 50 values of cDDP and ADM were reduced by approximately 7 fold and 130 fold respectively in the transfected cells as compared with the untransfected ones. Lower concentration of the chemotherapeutic agents (1.25 μmol/L of cDDP and 0.05 μmol/L of ADM) could be employed to suppress markedly the growth of the transfected H1299 cells. The apoptotic rate induced by cDDP was increased from 10.1% to 38 4% (P<0.01) and that of ADM from 12.1% to 49.3% (P<0.01). The clonogenecity after the administration of chemotherapeutic agents was significantly lower in the transfected H1299 cells than in the parental cells (P<0.01). The sensitive enhancement ratios were 1.8 and 2.6 for cDDP and ADM respectively. Conclusion: The transfection of H1299 cells with wild type p73α gene results in an increase of the sensitivity of the cells to chemotherapeutic agents.

Chemotherapy of cerebral gliomas directed by the chemosensitivity test in vitro: a clinical study

Objective： To evaluate correlation between chemosensitivity of tumor cells in vitro and their clinical responsiveness in vivo by comparing the difference of curative effect between chemotherapy of cerebral gliomas directed by chemosensitivity test in vitro and its routine chemotherapy. Methods： Sixty-two patients with cerebral gliomas were recruited as the experiment group, who had received total resection or subtotal resection of the tumor. The resected tumor cells were cultured in vitro, followed by chemosensitivity test using colorimetric MTT assay. Finally, chemotherapeutic protocol was made based on the results of the chemosensitivity test. Fifty patients with cerebral gliomas subjected to the routine chemotherapeutic protocol were simultaneously recruited as the control group, whose age, gender, survival functional status and operational fashion were matched with the experiment group. The two groups were equally followed up for the survival functional status, recurrence and death. All data were analyzed using SPSS 10.0 software. Results： At the time of evaluation, KPS values of 64.52 ± 35.84 were seen in the experiment group, and 33.60 ± 36.24 in the control group, showing statistical difference between the two groups （t = 4.5163, P = 0.000）. During 2-4 years of follow up, a recurrence rate of 32.26% was seen in the experimental group, and 60.00% in the control group, showing a statistical difference between the two groups （X^2 = 8.620, P = 0.003）. The fatality was 22.58% in the experiment group, and 48.00% in the control group, showing a statistical difference between the two groups （X^2 = 7.978, P = 0.005）. The survival rate of the experimental group was higher than that of the control group, showing a statistical differences between the two groups （X^2= 7.29, P = 0.0069）. Conclusion： Chemotherapy of glio- mas under the guidance of chemosensitivity test in vitro contributes to obvious improvement on the current survival functional status, a clear decline of the recurrence rates and fatality rate, and raised survival rates of the patients. A close correlation between the chemosensitivity in vitro and clinical responsiveness in vivo is observed.

A case of advanced intrahepatic cholangiocarcinoma successfully treated with chemosensitivity test-guided systemic chemotherapy

Intrahepatic cholangiocarcinoma （ICC） is a relatively rare and highly fatal neoplasm that arises from the biliary epithelium. Prognosis is generally poor and survival is limited to a few months. Here we present a case of advanced ICC successfully treated by chemosensitivity test-guided systemic chemotherapy combining S-1 and cisplatin （CDDP）. A 65-year-old woman with a liver tumor was referred to our hospital on November 21, 2007. Abdominal ultrasonography and computed tomography （CT） showed low-density masses of 50 and 15 mm in diameter, respectively in segment w of the liver and in the enlarged lymph node in the para-aorta. Ultrasonography-guided fine needle biopsy diagnosed the tumors as ICC. Since the patient was inoperable for lymph node metastasis, she underwent systemic chemotherapy with gemcitabine. Six months afcer initiation of chemotherapy, CT revealed ICC progression in the liver and pleural dissemination with pleural effusion. The patient was admitted to our hospital for anticancer drug sensitivity testing on June 9, 2008. Based on the sensitivity test results, we elected to administer systemic chemotherapy combining S-1 and CDDP. Two months into the second chemotherapy treatment, CT revealed a reduction of the tumors in the liver and lymph node and a decrease in pleural effusion.After eight cycles of the second chemotherapy, 17 mo after ICC diagnosis, she is alive and well with no sign of recurrence. We conclude that chemosensitivity testing may effectively determine the appropriate chemotherapy regimen for advanced ICC.

Impact of MTT based tumor chemosensitivity assay in vitro

Objective： The aim of the study was to evaluate the impact of the chemosensitivity assay in vitro and establish a standard process of measuring the anti-cancer drug sensitivity with MTT assay. Methods： Some influencing factors of MTT assay in studying the sensitivity of human peripheral blood mononuclear cells （PBMC） to anti-cancer drugs were observed, including red blood cells, platelets, three different kinds of DMSO and different concentrations of MTT. Meanwhile the stability of tumor drug-coated plate was monitored. Results： The red blood cells and platelets may affect the results at a certain range of concentration. Analytical pure DMSO, both imported and domestic reagents showed the same color with MI3-, and the A values of the reaction were dependent on MTT dose. The stability of the freeze-drying drug-coated plates was superior to non freeze-drying ones. Conclusion： To make clear and definite all kinds of influencing factors might contribute to a kind of standard MTT assay for drug sensitivity test in vitro.

Increased leucine-rich repeats and immunoglobulin- like domains 1 expression enhances chemosensitivity in glioma

Leucine-rich repeats and immunoglobulin-like domains 1 （LRIG1） is an anti-oncogene. LRIG1 is correlated with Bcl-2 in ependymomas. Decreased Bcl-2 and manganese superoxide dismutase expression can improve the chemosensitivity of glioma. In the present study, a tissue microarray of human brain astrocytomas was constructed. To investigate the relationship of LRIG1 with Bcl-2 and manganese superoxide dismutase, LRIG1, Bcl-2 and manganese superoxide dismutase expression in our tissue microarray was determined using immunohistochemistry. In addition, we constructed the LRIG1-U251 cell line, and its responses to doxorubicin and temozolomide were detected using the MTT assay. Results showed that LRIG1 expression was significantly negatively correlated with Bcl-2 and manganese superoxide dismutase expression in glioma. Also, proliferation of LRIG1-U251 cells exposed to doxorubicin or temozolomide was significantly inhibited, i.e. in the LRIG1-U251 cell line, the chemosensitivity to doxorubicin and temozolomide was increased. This indicates that increased LRIG1 expression produces a chemosensitivity in glioma.

Application value of ATP based bioluminescence tumor chemosensitivity assay in the chemotherapy for hydrothorax caused by non-small cell lung cancer

Objective： The aim of the study was to investigate the clinical value and application of ATP based bioluminescence tumor chemosensitivity assay （ATP-TCA） in the chemotherapy for hydrothorax caused by non-small cell lung cancer （NSCLC）. Methods： Hydrothorax specimens from 120 NSCLC patients were analyzed by ATP-TCA and the most sensitive chemotherapeutic drugs were used in NSCLC patients （treatment group）. At the same time, 56 NSCLC patients with hydrethorax were admitted in our Hospital （Department of Oncology, The No. 2 People＇s Hospital of Yibin, China） and given chemotherapy without guidance of the ATP-TCA （control group）. Before the third chemotherapeutic cycle, clinical outcomes were analyzed in the two groups. Results： Effective rate of hydrothorax in treatment group was 67%, while 46% in control group （P 〈 0.05）. In refractory hydrothorax patients, they were 69% and 40% （P 〈 0.05）, respectively.In vitro results correlated well with clinical outcomes （P 〈 0.01）. Conclusion： Effective rate of chemotherapy for hydrothorax in NSCLC is higher in treatment group than that in control group. ATP-TCA is especially helpful for refractory hydrothorax.

Loss of heterozygosity for loci on chromosome arms 1p and 10q in oligoden-droglial tumors: relationship to outcome and chemosensitivity

Oligodendroglial tumors frequently have deletions ofchromosomal loci on lp and l9q.Loas of heterozygosity(LOH)of chromosome 10 may be a negative prognostic factor.We reviewed 23 patients with oligodendroglial tumors,toevaluate the frequency of lp and 10q LOH and correlate with clinical outcome.Three loci(DlS402,DlSl 172,MCT118)on lp and 2 loci(Dl0S520 and D10S521)on 10q were analyzed for LOH using PCR techniques.

GLUTATHIONE S TRANSFERASE-π EXPRESSION IN HU- MAN GASTRIC CANCER AND ITS RELATIONSHIP TO CHEMOSENSITIVITY

Objective To investigate the expression of glutathione S transferase π(GST-π) in gastric carcinoma tissue sections,and its relationship to the clinicopathological parameters and the results of chemosensitivity testing on the freshly purified human gastric cancer cells. Methods Expression of GST-π in 39 gastric cancer specimens was detected by immunohistochemical method.Simultaneously,the chemosensitivity of individual cases to 5-FU,CDDP,MMC and ADM was determined by using MTT colorimetric assay. Results The percentage of positive GST-π was 66.7%,while that of negative was 33.3%.No significant correlation between the expression of GST-π and clinicopathologic features was observed.There was a statistical significance of the correlation of GST-π expression with drug resistance of gastric cancer to CDDP and MMC. Conclusion Over-expression of GST-π in gastric cancer tissue may be related to the drug resistance to CDDP and MMC.It is therefore important to select carefully the optimal anticancer drug for patients with highly positive GST-π expression.

Study on the influence of curcumin on chemosensitivity of nephroblastoma cells

Objective:To study the influence of curcumin on chemosensitivity of nephroblastoma cells.Methods:Human nephroblastoma cells line SK-NEP-1 was transplanted to the nude mice subcutaneously to establish the implantation tumor model of human nephroblastoma cells.A total of 30 tumor-bearing mice were divided into three groups of ten randomly.The routine chemotherapy group was given vincristine(0.05 mg/mL·0.2 mL/d) and actinomycin D(15 ng/mL·0.2 mL/d) combined chemotherapy regime.The curcumin chemotherapy group was given the same combined chemotherapy regimens and curcumin(30 mg/kg/d) by intraperitoneal injection.The control group was given normal saline(NS) of the same volume by intraperitoneal injection.Continuous administration would be kept for 4 weeks and 3 days a week.The volumetric changes of every group were recorded.The serum of every group in different time was collected and the VEGF content was detected by ELISA.All mice were cercrificed and the tumor tissues were stripped and weighed after 4 weeks’ treatment.The tumor inhibition rate was calculated.The cell proliferation activity and apoptosis rate were detected by MTT and flow cytometry method.All data were statistically analyzed by SPSS 19.0.Results:The tumor volume,serum VEGF content,tumor inhibition rate,cell proliferation activity and apoptosis rate of routine chemotherapy group and curcumin chemotherapy group had significant differences comparing with the control group(P<0.05) after 4-week’s treatment.The cancer growth of curcumin chemotherapy group was obviously decreased and even tended to shrink comparing with routine chemotherapy group(χ2=15.732,P=0.007).The cell proliferation activity was significantly reduced and the apoptosis rate was significantly higher,(χ~2=9.427,P=0.012)which showing the effect of chemotherapy was enhanced.Conclusions:The chemosensitivity of nephroblastoma cells could be improved by curcumin,then the effect of preoperative adjuvant chemotherapy scheme would be enhanced,the growth of nephroblastoma cells would be inhibited and the surgical risk of nephroblastoma would be reduced.

STUDY ON RELATIONSHIP BETWEEN CHEMOSENSITIVITY OFBREAST CANCER AND EXPRESSION OF p73α AND p53

Objective： To investigate the relationship between the expression of p73α and p53 versus the chemosensitivity in breast cancer cells. Methods： Twelve surgical samples of breast cancer diagnosed by pathology were used. The cancer sample cells were separately cultured in the incubator at 37℃, 5% CO2 in vitro. The relative inhibition rate of cancer cells by 4 kinds of anticancer drugs, which were EPI, MMC, 5-Fu and DDP, were assayed by MTT method. Immunocytochemistry was used to detect the expression of p73α and p53 in the cancer cells. Results： The positive expression of p73α was found in 5/12 （41.67%）, and p53 positive expression rate was 50.0% （6/12）. The relative inhibition rate of MMC, EPI, 5-Fu and DDP were significantly higher in the p73α positive cancer cells than in the p73α negative cancer cells. A positive correlation was found between expression of p73α and chemosensitivity for all the four anticancer drugs. Condusion： The expression of p73α is related with the chemosensitivity of the breast cancer cells, and it may become one of the markers for judging the effect of chemotherapy in clinic.

EFFICACY OF IFOSFAMIDE AND VP-16 (ETOPOSIDE) IN PATIENTS WITH SMALL CELL LUNG CANCER AND THE CORRELATION BETWEEN MICROVESSEL COUNT ON CHEMOSENSITIVITY

Objective： To evaluate the efficacy of ifosfamide and etoposide （VP-16） in patients with small cell lung cancer （SCLC）, and investigate the correlation between microvessel count （MVC） in tumor and chemotherapeutic sensitivity. Methods： Forty-one consecutive cases of SCLC received chemotherapy of ifosfamide plus VP-16, and underwent investigation retrospectively. Immunohistochemistry using anti-human blood type H monoclonal antibody was conducted and MVC was recorded under light microscope. Results： There were 27 limited-disease and 14 extensive-disease patients. The overall response rate was 92.7% （38/41） with 28 cases （68.3%） of complete response （CR）, 10 （24.4%） with partial response （PR）, 3 （7.3%） with progressive disease （PD）. The 1-, 2-, 3-, and 5-year survival rates were 68.3% （28/41）, 48.3% （20/41）, 23.7% （9/38） and 11.1% （3/27）, respectively, with the median survival of 26.8 months. The principal toxicities were grade 3-4 neutropenia in 8 cases （19.5%）, grade 3-4 thrombocytopenia in 6 cases （14.6%）, mild liver toxicity in 7 cases （17.0%） and mild renal function damage in 4 cases （9.8%）. The mesenchymal vasculature was clearly visualized, with the mean value of 34.7 under each high microscopic power field. Of SCLC with more MVC （n=26）, CR accounted for 84.6%; while in cancers with less MVC （n=l 5）, CR took up 40.0%, with significant difference （P〈0.05）. Conclusion： Administrating ifosfamide and VP-16 is in accordance with the biological features of SCLC and results in beneficial results as well as acceptable side effects. The MVC is positively correlated with the chemotherapeutic sensitivity, and serves as a vital factor contributing to chemosensitivity.

Distinct Immune Signatures in Peripheral Blood Predict Chemosensitivity in Intrahepatic Cholangiocarcinoma Patients

Intrahepatic cholangiocarcinoma(ICC)is the second most common liver cancer.Chemotherapy remains the main therapeutic strategy for advanced ICC patients,but chemosensitivity varies individually.Here,we applied cytometry by time-of-flight(CyTOF)to establish the immune profile of peripheral blood mononuclear cells(PBMCs)on the single-cell level at indicated time points before,during,and after chemotherapy.Multiplex immunofluorescence staining was applied to examine the spatial distribution of certain immune clusters.Tissue microarrays(TMAs)were used for prognostic evaluation.A total of 20 ICC patients treated with gemcitabine(GEM)were enrolled in our study,including eight cases with good response(R)and 12 cases with non-response(NR).Tremendous changes in PBMC composition,including an increased level of CD4/CD8 double-positive T cells(DPT),were observed after chemotherapy.Patients with higher level of CD4^(+)CD45RO^(+)CXCR3^(+)T cells before treatment had a favorable response to chemotherapy.Our study identified a positive correlation between the percentage of T cell subpopulations and clinical response after chemotherapy,which suggests that it is practical to predict the potential response before treatment by evaluating the proportions of the cell population in PBMCs.

CHEMOSENSITIVITY OF MGc80-3 HUMAN GASTRIC ADENOCARCINOMA CELLS AND ITS CLINICAL SIGNIFICANCE

In the present study, the chemosensitivity of MGc80-3 human gastric adenocarcinoma cells was determined by means of colony-forming assay and the in vitro activities of 10 anticancer drugs were examined on the basis of the clinically achievable peak plasma drug concentration. The results showed that MGc80-3 cells were most sensitive to mitomyc'n C, adriamycin and 5-fluorouracil, being consistent with the response noted in clinical gastric cancer. This cell line may retain its original drug sensitivity and may be useful in screening for new compounds with activity against this disease.

EFFECTS OF p16^(INK4) GENE ON CHEMOSENSITIVITY OF HUMAN GLIOMA U251 CELL LINE TO TENIPOSIDE

Objective: To determine the effects on the cell growth, tumorigenicity and chemosensitivity of p16/CDK4I in human glioma. Methods: p16 gene was transfected into U251 cells by lipofectin. Expression of exogenous p16 gene was confirmed by immunohistochemistry and Northern blot. The effects of exogenous p16 gene on the growth and chemosensitivity to teniposide were examined. Results: Expression of exogenous p16 gene inhibited the growth dramatically in vitro. G1 arrest of tumor cells was observed. However, wt p16-positive U251 was less sensitive than control cell lines and the number of apoptotic cells after chemotherapy was reduced. Conclusion: The expression of exogenous p16 gene could inhibit the growth of glioma. On the other hand, the chemosensitivity to teniposide of p16-positive U251 was decreased.