The catalytic subunit of DNA-dependent protein kinase selectively regulates p53-dependent apoptosis but not cell-cycle arrest

DNA damage induced by ionizing radiation (IR) activates p53, leading to the regulation of downstream pathways that control cell-cycle progression and apoptosis. However, the mechanisms for the IR-induced p53 activation and the differential activation of pathways downstream of p53 are unclear. Here we provide evidence that the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) serves as an upstream effector for p53 activation in response to IR, linking DNA damage to apoptosis. DNA-PKcs knockout (DNA-PKcs-/-) mice were exposed to whole-body IR, and the cell-cycle and apoptotic responses were examined in their thymuses. Our data show that IR induction of apoptosis and Bax expression, both mediated via p53, was significantly suppressed in the thymocytes of DNA-PKcs-/- mice. In contrast, IR-induced cell-cycle arrest and p21 expression were normal. Thus, DNA-PKcs deficiency selectively disrupts p53-dependent apoptosis but not cell-cycle arrest. We also confirmed previous findings that p21 induction was attenuated and cell-cycle arrest was defective in the thymoctyes of whole body-irradiated Atm-/- mice, but the apoptotic response was unperturbed. Taken together, our results support a model in which the upstream effectors DNA-PKcs and Atm selectively activate p53 to differentially regulate cell-cycle and apoptotic responses. Whereas Atm selects for cell-cycle arrest but not apoptosis, DNA-PKcs selects for apoptosis but not cell-cycle arrest.

Fast and quantitative high-performance liquid chromatography method for the determination of 9-fluorenylmethoxycarbonyl release from solid-phase synthesis resins

Base catalyzed cleavage of 9-fluorenylmethoxycarbonyl (FMOC) group and subsequent analysis by UV spectrophotometry is a commonly used technique for measuring the loading of functional groups on solid supports. Recent works suggest that using 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) instead of piperidine makes it possible to use gas chromatography for quantitation, but due to the long deprotection time used, the method is not high-throughput. We observed that the dibenzofulvene released after DBU deprotection could be measured by reversed-phase (RP) HPLC. We have optimized the concentration of DBU as well as the time of the deprotection and coupled with a fast RP-HPLC separation results in a highly reproducible, high-throughput method. The measured loading correspond well with the manufacturer's data on several commercial resins. Using this method we have quantitated the amine loading on several polystyrene resins and we have found that the total amount of functional group can be more than twice the amount of the available ones. We concluded that the differences were the function of the resin loading as well as the level of crosslinking.

Stereoselective formation of seven-coordinate titanium(IV) monomer and dimer complexes of ethylenebis(o-hydroxyphenyl)glycine

Reactions between the antitumor agent titanocene dichloride (Cp2TiCl2) and the hexadentate ligand N,N'-ethylenebis-(o-hydroxyphenylglycine) (H4ehpg) have been investigated in aqueous solution and the solid state. The racemic ligands give crystals of the monomer [Ti(ehpg)(H2O)] x (11/3)H2O (1), while the meso ligand gives the oxo-bridged dimer [[Ti(Hehpg)(H2O)]2O] x 13H2O (2). Complex 1 crystallizes in the monoclinic space group C2/c with a = 24.149(4) A, b = 14.143(3) A, c = 19.487(3) A, beta = 105.371(13) degrees, V = 6417.7(19) A3, Z = 12, and R(F) = 0.0499 for 4,428 independent reflections having I > 2sigma(I), and contains seven-coordinate pentagonal-bipyramidal TiIV with two axial phenolate ligands (Ti-O, 1.869(2) A). The pentagonal plane contains the two N-atoms at 2.210(2) A, two carboxylate O-atoms at 2.061(2) A, and a water molecule (Ti-OH2, 2.091(3) A). Complex 2 crystallizes as an oxygen-bridged dimer in the triclinic space group P-1 with a = 12.521(6) A, b = 14.085(7) A, c = 16.635(8) A, alpha = 80.93(2) degrees beta = 69.23(2) degrees, gamma = 64.33(2) degrees , V = 2472(2) A3, Z = 4, and R(F) = 0.0580 for 5956 independent reflections having I > 2sigma(I). Each seven-coordinate, pentagonal-bipyramidal TiIV has a bridging oxide and a phenolate as axial ligands. The pentagonal plane donors are H2O, two carboxylate O-atoms, and two NH groups, which form H-bonds to O-atoms both in the same half-molecule (O...N, 2.93-3.13 A) and in the other half-molecule (O...N, 2.73-2.75 A); the second phenoxyl group of each Hehpg ligand is protonated and not coordinated to TiIV, but H-bonds to a nearby amine proton (O...N, 2.73-2.75 A) from the same ligand and to a nearby H2O (O...O, 2.68 A). In contrast to all previously reported crystalline metal-EHPG complexes containing racemic ligands, in which the N(S,S)C(R,R) or N(R,R)C(S,S) form is present, complex 1 unexpectedly contains the N(S,S)C(S,S) and N(R,R)C(R,R) forms. This is attributed to the presence of ring strain in seven-coordinate TiIV complexes. Moreover, the rac ligands selectively form crystals of monomeric 1, while the meso ligand selectively forms crystals of the dimer 2 (N(R,R)C(R,S) or N(S,S)C(S,R)). Complexes 1 and 2 exhibit phenolate-to-TiIV charge-transfer bands near 387 nm, and 2D NMR studies indicate that the structures of 1 and 2 in solution are similar to those in the solid state. Complex 1 is stable over the pH range 1.0-7.0, while 2 is stable only between pH 2.5 and pH 5.5. Cp2TiCl2 reacts with EHPG at pH* 7.0 to give complex 1 with a t 1/2 of ca. 50 min (298 K), but complex 2 was not formed at this pH* value. At pH* 3.7, the reaction is very slow: 1 forms with a half-life of ca. 2.5 d, and 2 after ca. 1 week at ambient temperature. The relevance of these data to the possible role of serum transferrin as a mediator for the delivery of TiIV to tumor cells is discussed.

[The clinic application of multichannel cochlear implant with eleven cases reported]

OBJECTIVE

To review the effects of profound sensorineural deaf patients who were implanted multichannel cochlear.

METHOD

Eleven profound deaf patients (6 prelingually deaf and 5 postlingually deaf) were implanted with twenty-two (model Minisystem 22) and twenty-four (model Nucleus 24) channel cochlear. Mapping of cochlear speech processor was done in 1 to 1.5 months after operation.

RESULT

All of 11 patients obtained the hearing. The patients with postlingually deaf can dialog and communicate with telephone after a simple language training without lip reading training. These patients achieved the best results, they not only stepped in sound world but also obtained a normal living and work. In the prelingually deaf patients, they got hold of incoordinate progress in speech ability after assess and speech training.

CONCLUSION

The multichannel cochlear implant had good effects in profound deaf patients, especial in postlingually deaf patients and younger children.

Cell proliferation and apoptosis

Cell proliferation and cell death are essential yet opposing cellular processes. Crosstalk between these processes promotes a balance between proliferation and death, and it limits the growth and survival of cells with oncogenic mutations. New insights into the mechanisms by which strong signals to proliferate and activation of cyclin-dependent kinases promote apoptosis have recently been published, and a novel cell cycle regulated caspase inhibitor, Survivin, has been described.

Nodular sarcoid myositis of skeletal muscle diagnosed by fine needle aspiration biopsy. A case report

BACKGROUND

Symptomatic striated muscle involvement in sarcoidosis is rare. Muscle biopsy is usually required for the diagnosis. Fine needle aspiration biopsy (FNAB) has been successfully used in diagnosing soft tissue lesions. To the best of our knowledge, FNAB of sarcoid myositis has not been reported.

CASE

A 31-year-old, black female with a history of sarcoidosis presented with an enlarging, painful, left calf mass. Infected thrombi were suspected. FNAB showed numerous loosely arranged epithelioid histiocytes, multinucleated giant cells and skeletal muscle cells. The overall cytologic picture was that of granulomatous myositis. The cytologic features coupled with the patient's history and magnetic resonance imaging findings suggested sarcoid myositis. Subsequent muscle biopsy showing noncaseating granulomata and negative stains for organisms confirmed the diagnosis of nodular sarcoid myositis.

CONCLUSION

Nodular sarcoid myositis can be suggested by FNAB cytology in a patient with a past history of sarcoidosis.

Molecular characterization of a porcine enteric calicivirus genetically related to Sapporo-like human caliciviruses

Porcine enteric calicivirus (PEC) is associated with diarrhea in pigs, and to date it is the only cultivable enteric calicivirus (tissue culture-adapted [TC] PEC/Cowden). Based on sequence analysis of cDNA clones and reverse transcription-PCR products, TC PEC/Cowden has an RNA genome of 7,320 bp, excluding its 3' poly(A)(+) tail. The genome is organized in two open reading frames (ORFs), similar to the organizations of the human Sapporo-like viruses (SLVs) and the lagoviruses. ORF1 encodes the polyprotein that is fused to and contiguous with the capsid protein. ORF2 at the 3' end encodes a small basic protein of 164 amino acids. Among caliciviruses, PEC has the highest amino acid sequence identities in the putative RNA polymerase (66%), 2C helicase (49.6%), 3C-like protease (43.7%), and capsid (39%) regions with the SLVs, indicating that PEC is genetically most closely related to the SLVs. The complete RNA genome of wild-type (WT) PEC/Cowden was also sequenced. Sequence comparisons revealed that the WT and TC PEC/Cowden have 100% nucleotide sequence identities in the 5' terminus, 2C helicase, ORF2, and the 3' nontranslated region. TC PEC/Cowden has one silent mutation in its protease, two amino acid changes and a silent mutation in its RNA polymerase, and five nucleotide substitutions in its capsid that result in one distant and three clustered amino acid changes and a silent mutation. These substitutions may be associated with adaptation of TC PEC/Cowden to cell culture. The cultivable PEC should be a useful model for studies of the pathogenesis, replication, and possible rescue of uncultivable human enteric caliciviruses.

Advantages of concurrent biochemotherapy modified by decrescendo interleukin-2, granulocyte colony-stimulating factor, and tamoxifen for patients with metastatic melanoma

PURPOSE

Concurrent biochemotherapy results in high response rates but also significant toxicity in patients with metastatic melanoma. We attempted to improve its efficacy and decrease its toxicity by using decrescendo dosing of interleukin-2 (IL-2), posttreatment granulocyte colony-stimulating factor (G-CSF), and low-dose tamoxifen.

PATIENTS AND METHODS

Forty-five patients with poor prognosis metastatic melanoma were treated at a community hospital inpatient oncology unit affiliated with the John Wayne Cancer Institute (Santa Monica, CA) between July 1995 and September 1997. A 5-day modified concurrent biochemotherapy regimen of dacarbazine, vinblastine, cisplatin, decrescendo IL-2, interferon alfa-2b, and tamoxifen was repeated at 21-day intervals. G-CSF was administered beginning on day 6 for 7 to 10 days.

RESULTS

The overall response rate was 57% (95% confidence interval, 42% to 72%), the complete response rate was 23%, and the partial response rate was 34%. Complete remissions were achieved in an additional 11% of patients by surgical resection of residual disease after biochemotherapy. The median time to progression was 6.3 months and the median duration of survival was 11.4 months. At a maximum follow-up of 36 months (range, 10 to 36 months), 32% of patients are alive and 14% remain free of disease. Decrescendo IL-2 dosing and administration of G-CSF seemed to reduce toxicity, length of hospital stay, and readmission rates. No patient required intensive care unit monitoring, and there were no treatment-related deaths.

CONCLUSION

The data from this study indicate that the modified concurrent biochemotherapy regimen reduces the toxicity of concurrent biochemotherapy with no apparent decrease in response rate in patients with poor prognosis metastatic melanoma.

Immunohistochemical detection of breast cancer cells in paired peripheral blood progenitor cell specimens collected after cytokine or cytokine and myelosuppressive chemotherapy

Mobilized peripheral blood progenitor cells (PBPC) from 30 patients with advanced breast cancer were studied for the presence of tumor cell contamination using a highly sensitive immunohistochemical technique with the capacity to detect one tumor cell in one million mononuclear cells. Aliquots of PBPC were obtained after 4 days of G-CSF and/or GM-CSF and again during G-CSF-stimulated recovery from myelosuppressive doses of cyclophosphamide. The overall incidence of tumor cell contamination was 23%, occurring in PBPC specimens from seven of 30 patients. All four cases in which tumor cells were detected after mobilization with cytokine alone also had tumor cells detected in PBPCs collected following chemotherapy and G-CSF. There were three cases in which malignant contamination was detected only in the specimens collected after cyclophosphamide. There was a greater frequency of tumor cell contamination in aphereses performed during G-CSF-stimulated recovery from cyclophosphamide than in collections primed by cytokine alone (13% vs 23%; P = 0.08), although this did not reach statistical significance. This trend suggests that collection of PBPC during cytokine-stimulated recovery from myelosuppressive chemotherapy may be associated with a greater risk of contamination with malignant cells than apheresis during mobilization with cytokines in the steady state.

The radial pattern of basilar membrane motion evoked by electric stimulation of the cochlea

Electric current applied to the cochlea can evoke in situ electromotile responses of the organ of Corti. These nonsound-generated responses can give insight into the mechanics of the organ as the putative forces produced by outer hair cells (OHC) must couple to the modes of vibration of the basilar membrane (BM). In this study, platinum-iridium wire electrodes were positioned into the scala vestibuli and scala tympani of the first cochlear turn in the guinea pig. Current (1.5 ms rectangular-shaped pulses) was applied to these electrodes at levels to 500 microA peak. A laser Doppler velocimeter was used to record the velocity or displacement of the basilar membrane at the tonotopic 18 kHz place via an opening into the scala tympani of the first cochlear turn. Beads were positioned across the width of the BM so that the velocity or displacement of the BM could be studied in the radial direction. It was found that the current pulses evoked linear displacements of up to 2 nm for current levels of 500 microA (higher levels were damaging to the organ of Corti). The pattern of motion across the width of the BM was such that maximum displacement and velocity was located near the first row of OHCs and the position of the outer pillar cell footplate. The BM motion was biphasic in that the zona arcuata moved in the opposite direction to that of the zona pectinata. The results of this study demonstrate that the level of force produced by OHCs is effective in moving the BM and that the distribution of force within the organ of Corti leads to a multimodal motion pattern of the BM for this experimentally artificial means of evoking OHC motion.

Rejoining of DNA double-strand breaks in Ku80-deficient mouse fibroblasts

The role of Ku80 in the repair of DNA double-strand breaks (DSBs) was examined in fibroblasts derived from a Ku80 knockout mouse model described by Nussenzweig et al. (Nature 382, 551-555, 1996). Primary fibroblasts from Ku80+/+ and Ku80-/- mice were immortalized by transfection with plasmids containing either the human MYC proto-oncogene or the Simian virus 40 (SV40) T antigen and were used to measure induction and rejoining of DSBs after exposure to ionizing radiation. The number of DSBs in the cells was quantified by either asymmetric field-inversion gel electrophoresis (AFIGE) or clamped homogeneous electrical-field gel electrophoresis (CHEF). The latter method was introduced for a more reliable quantification of repair even when DNA degradation occurs in a fraction of the irradiated cell population during the postirradiation incubation time. The results confirm that Ku80-deficient mouse fibroblasts are sensitive to ionizing radiation and demonstrate that the increased radiosensitivity may result from a deficiency in DSB rejoining. The results further indicate that unless techniques are employed that allow for distinction between DNA degradation and DNA repair, erroneous conclusions may be drawn regarding the potential of cells to repair DSBs.

Apoptotic cell death of human gastric tumor induced by nucleosides from CD57+HLA-DRbright natural suppressor cell line

CD57+HLA-DRbright natural suppressor (57.DR-NS) cell line derived from human decidual tissue generated apoptosis in a human gastric carcinoma cell line (GCIY) but not in a human diploid normal cell line (WI-38). The factors released from 57.DR-NS cells were purified by thin-layer-chromatography (TLC) and separated by high performance liquid chromatography (HPLC) into six components. The physicochemical structures of the six components were determined as a series of nucleosides and their modified forms collectively termed <apoptosis inducing nucleosides (AINs)> in a previous study. They could generate apoptotic cell death of GCIY malignant target cells, but not disturb the viability of WI-38 normal target cells. The administration of AINs into GCIY tumor bearing SCID mice resulted in drastic suppression of tumor growth followed by the decrease in tumor size due to the occurrence of apoptosis in tumor tissues.

[Report of myringoplasty with interlay method in 53 ears perforation of tympani]

OBJECTIVE

To probe into an eutherapeutic method for the healing tympanic membrane aperture.

METHOD

Fifty-three cases of tympamic membrane aperture were treated with myringoplasty of interlay method. The results were compared with that of underlay method of 168 ears in same period.

RESULT

The rate of closure of perforation of tympani was 96.2% in interlay method group and 85.7% in underlay method. The hearing recovery of interlay method group was better than underlay method group. Function of Eustachian tube kept good condition in interlay method group. There was no blunting of anterior tympanomeatal angle in the interlay group.

CONCLUSION

The interlay method of myringoplasty is an ideal method for healing perforation of tympani.

[The effects of substance P antibody on tuning curve of auditory evoked potential of cochlear nucleus and inferior colliculus in guinea pigs]

OBJECTIVE

To explore the effects of substance P on the frequency analysis of sound signals in the auditory brainstem.

METHODS

The electrodes were implanted into the cochlear nucleus (CN) and the inferior colliculus (IC) of guinea pigs. The auditory evoked potential in CN (CN-AEP) and IC (IC-AEP) was recorded with tone pip stimulation and tone burst forward masking techniques. The Q10 dB values of the tuning curves were compared between the CN-AEP and IC-AEP after injection of SP antibody or rabbit serum with the same dosage (used as control) into the nucleus.

RESULTS

After injection of SP antibody, the Q10 dB values of the tuning curves of CN-AEP and IC-AEP had no significant changes in 1 kHz and 2 kHz probe tone groups. When probe tone frequencies were 4 kHz and 6 kHz, there was a significant difference between the two frequency groups in Q10 dB. In addition, the higher frequency slope and lower frequency slope value had corresponding changes.

CONCLUSION

The results imply that SP could act as a neuromediator in the auditory afferent system and participated in the high frequency analysis in the auditory brainstem.

Basal cell carcinoma with lung metastasis diagnosed by fine-needle aspiration biopsy

Basal cell carcinoma of the skin is one of the most common types of cancer. Its natural history is one of local recurrence rather than metastatic spread. Certain histologic features and primary tumor size seem to be risk factors for metastases. The diagnosis of metastatic disease imparts a poor prognosis with a short median survival. Treatment is usually in the form of systemic chemotherapy with cisplatin-based combination described as most active agent.

[Electrically evoked otoacoustic emissions and their distortion products in guinea pigs]

The objective of this study was to investigate micromechanical properties and electromotility of cochlear outer hair cells in vivo. Extracochlear electrically stimulation with sinusoid alternating current was delivered to cochlea of guinea pigs. Sound pressure level was recorded from ear canal by microphone and the electrically evoked otoacoustic emissions (EEOE) and their distortion products (DPEEOE) were analyzed with FFT spectrum analyzer. The EEOE in 3 kHz to 33 kHz were recorded from 15 guinea-pigs in 18 guinea-pigs, the transfer function was more smooth in 8 kHz to 31 kHz. The DP EEOE were very clear when F1 = 6 kHz, F2 = 7.2 kHz, and the current intensity higher than 100 microA. While the intensity increased to 300 microA, two distortion products, F2-F1 and 2(2F1-F2)-F1, could be seen in addition to 2F1-F2. The input-output function showed that EEOE and DP EEOE I/O function were linear when lower electric intensity stimulation was given, but they displayed compress non-linear features when higher intensity current was delivered. The authors conclude that EEOE and DP EEOE are expression of electrophonic hearing characteriged by wide frequency bandpass appearance, wide dynamic range and non-linear features, so they are good tools for studying the mechanical properties of outer hair cells and the integrate function of Corti's organ.

[Cytogenetic analysis and bcr/abl mRNA detection in chronic myeloid leukemia]

OBJECTIVE

To define the relationship between Ph chromosome and BCR/ABL mRNA expression in chronic myeloid leukemia (CML) patients, and compare cytogenetic analysis and PCR method.

METHODS

Marrow or peripheral blood samples from 33 CML patients were analyzed by R banding technique and PCR method. Eleven patients who received allogeneic BMT or alpha-IFN + low dose HU were followed up.

RESULTS

In 33 patients, 29 were Ph(+), 30 expressed BCR/ABL mRNA. In 6 patients who received BMT, 4 were Ph(-), 2 were Ph(+). However, 2 patients were (-), 4 were (+) by PCR method. In 5 patients who received alpha-IFN, the percentage of Ph(+) cells reduced after 6 and 12 months treatment than before treatment in 2 cases respectively. In 41 samples, 34 cases were consistent by 2 methods.

CONCLUSION

Each method, Cytogenetic analysis or PCR has its advantage and defect. The better method are integration of 2 methods in diagnosis and treatment monitoring of CML patients, so that provide real and beneficial information for clinic.

[Smoking, related cancers, and other diseases in shanghai: a 10-year prospective study]

OBJECTIVE

To explore the relationship between smoking and related diseases among residents of Shanghai.

METHODS

A cross-sectional study on current smoking status among 213,800 residents aged 20 yr and over in Shanghai urban, suburb and rural areas was carried out during the early 1980s. The residents in the urban area were followed up for 12 years (1983 - 1994) and those in suburb and rural areas for 11 years (1984 - 1994). A Poisson regression model was used to estimate relative risks RRs of certain diseases for smoking adjusted for age with their 95% confidence intervals by sex and area among persons aged 40 yr and over at the beginning of the study.

RESULTS

In the urban area, the RRs of death for smoking were 1.48 and 1.62 in males and females, respectively and for cancer death were 2.20 and 2.00. Statistically significant elevated RRs were seen for cancers of the lung and liver in both males and females and for cancers of the oesophagus, stomach, pancreas and bladder only in males. Significantly higher RRs were also observed for cerebrovascular disease, chronic bronchitis and emphysema, and pulmonary heart disease. RRs lower than in the urban area were found in the suburb and rural areas. The population attributable risks (%, PAR) for death due to smoking for males were estimated by area. PARs for death were 20.9, 18.9 and 16.3 in urban, suburb and rural areas, respectively. For all cancers, PARs were 40.0, 34.5 and 34.2 and for lung cancer were 71.7, 59.2 and 64.7.

CONCLUSION

Smoking was associated with the mortality of some common cancers, chronic bronchitis, and emphysema, pulmonary heart, and cerebrovascular diseases.

[Establishment of hybridoma secreting anti-mycobacteria monoclonal antibody by using electrofusion technique]

By using the electrofusion technique, the fusion of NS1 myeloma cells with spleen cells of BALB/c mouse immunized with five species of mycobacteria was carried out. With the optimal electrofusion conditions, we obtained a high fusion efficiency of 1.75 hybrid cell clones per 10(5) spleen cells. ELISA was used for screening secreting antimycobacteria McAb hybrid cells. After cloning, 22 stable hybrid cells lines were selected, and 8 of them had been studied.

Solid-phase stereoselective synthesis of 2'-O-methyl-oligoribonucleoside phosphorothioates using nucleoside bicyclic oxazaphospholidines

The use of 2'-OMe-ribonucleoside bicyclic oxazaphospholidines derived from (R)- or (S)-2-pyrrolidinemethanol has enabled the stereoselective synthesis of (Rp)-, and (Sp)-2'-O-methyloligoribonucleoside phosphorothioates. Interestingly, higher stereoselectivity (96-98%) was observed in the synthesis of (Sp)-2'-O-methyl-oligoribonucleoside phosphorothioates compared to that in the case of (Sp)-oligodeoxyribonucleoside phosphorothioates (90%).

[Aberrant expression of immunoglobulin germline gene C mu in leukemias]

OBJECTIVE

To investigate the significance of immunoglobulin germline gene C mu expression in leukemias.

METHODS

Immunoglobulin germline gene C mu transcripts in 63 bone marrow samples from 59 leukemia patients were examined by RT-PCR.

RESULTS

Germline C mu transcripts could be identified in 17 of 26 AML, 9 of 12 ALL, 4 CML-BC and 2 CLL patients. HLA-DR was expressed in 80% C mu(+) patients and in 92.9% C mu(+) AML patients. In 10 normal bone marrow or peripheral blood samples C mu transcripts were undetectable.

CONCLUSION

Leukemogenesis in most acute leukemia may originate from the common progenitors of early B-lymphoid and myeloid cells.

[Study on expression of nm23-H1 gene in laryngeal cancer tissues]

The nm23 gene is a metastasis suppressor gene. There are now two known isotypes of human nm23, namely nm23-H1 and nm23-H2. Several investigators have reported that reduced expression of nm23-H1 is associated with metastasis or disease progression in some of the tumor cases. In this study, the expression of nm23-H1 mRNA in the human laryngeal squamous cell carcinoma was investigated by Northern blot analysis. The levels of nm23-H1 mRNA were higher in cancers (n = 31) than in the adjacent normal tissues (n = 7), but the difference was not significant (P > 0.05). There was a significant decrease of nm23-H1 mRNA levels in tumors with lymph node metastasis (n = 11) as compared with those without (n = 20) (P < 0.01). Cancer tissues in clinical stages III-IV. (n = 23) also exhibited lower levels of nm23-H1 mRNA expression than those in stages I-II (n = 8) (P < 0.05). These results suggest that the nm23-H1 gene may play a role in the suppression of lymph node metastasis or disease progression in laryngeal cancer.