Simultaneous intrathyroidal parathyroid adenomas and multifocal papillary thyroid carcinoma in a patient with kidney transplantation: a case report.

BACKGROUND: Persistent hyperparathyroidism after kidney transplantation has been associated with adverse outcomes. Parathyroidectomy is the definitive treatment approach, but the success of parathyroidectomy relies on the accurate preoperative localization of the culprit parathyroid lesions. Simultaneous intrathyroidal parathyroid adenomas and multifocal papillary thyroid carcinoma present important diagnostic challenges. Here, we describe a patient with kidney transplantation who underwent successful surgery after being evaluated with functional and structural imaging. CASE PRESENTATION: A 53-year-old man presented with potentially malignant multifocal thyroid nodules by ultrasonography 2 years after kidney transplantation. The patient had hypercalcaemia and persistent hyperparathyroidism. Thyroid papillary carcinoma was confirmed in the left thyroid nodules by fine-needle aspiration biopsy. The right superior thyroid hypoechoic nodule was 1.2 cm in size and showed marked uptake of the tracer 99mTcO4-sestamibi during single-photon emission computed tomography/computed tomography (SPECT/CT); additionally, a cystic parathyroid lesion without tracer uptake was present behind the left superior pole of the thyroid. The histological examination demonstrated the coexistence of right intrathyroidal parathyroid adenomas, left cystic parathyroid nodular hyperplasia and multifocal papillary thyroid carcinoma. At the 6-month follow-up, the serum calcium levels were within the normal range, and the patient's kidney function remained stable. CONCLUSIONS: Simultaneous intrathyroidal parathyroid adenomas and multifocal papillary thyroid carcinoma in a patient with kidney transplantation is a rare clinical scenario. Physicians must be aware that the combination of functional (SPECT/CT) and structural (ultrasonography) imaging is highly successful in diagnosing patients with coexistent intrathyroidal parathyroid adenomas and papillary thyroid carcinoma.

Prevalence of dementia in the People's Republic of China from 1985 to 2015: a systematic review and meta-regression analysis.

BACKGROUND: In China, the most populous developing country in the world, dementia represents a serious challenge. We performed a large-scale systematic review and meta-regression analysis to elucidate the prevalence of dementia and its subtypes and to identify potential factors underlying the differences between articles. METHODS: A comprehensive literature search was conducted in the following databases to identify studies published up to December 2015: Cochrane Library, CBMDISK, Chongqing VIP, CNKI, PubMed and EMBASE. All statistical analyses (including subtype and meta-regression analyses) were performed with R version 3.3.3. RESULTS: In total, 51 surveys were selected. The pooled prevalence rates of dementia and its main subtypes, namely, Alzheimer's disease (AD) and vascular dementia (VAD), for the population aged 55 years and older were 4.03, 2.44 and 1.09%, respectively. The outcomes showed that the meta-regression analysis was affected by the publication year, sample size, region and diagnostic criteria. CONCLUSIONS: Our analysis provided reliable estimates of the prevalence of dementia/ AD/ VD over the past 30 years, which may be affected by education level, and diagnostic criteria. The prevalence of AD/VAD was higher in northern than in southern China, which warrants further study.

Pralatrexate mediates effective killing of gemcitabine-resistant pancreatic cancer: role of mTOR/4E-BP1 signal pathway.

Gemcitabine is the first-line chemotherapeutic agent for pancreatic cancer. However, gemcitabine-resistance frequently leads to poor prognosis. Exploring new chemotherapeutic agents is important for patients with gemcitabine-resistant pancreatic cancer. In this study, we established a new acquired gemcitabine-resistant pancreatic cancer cell line BxPC-GEM-20 from parental BxPC-3. We found that pralatrexate significantly inhibited the growth of BxPC-GEM-20. The half-maximal inhibitory concentration of pralatrexate on BxPC-GEM-20 cell was about 3.43 ± 0.25 nM. Pralatrexate was found to effectively inhibit the clonal growth of BxPC-GEM-20 cell. Additionally, pralatrexate at 20 mg/kg had an excellent tumor inhibitory effect with an inhibitory rate of 76.92% in vivo. This pralatrexate therapy showed good safety profile that with little to no additional influence on the hepatic, renal function as well as body weight changes in nude mice. Pralatrexate was confirmed to prevent cells from entering the G2/M phase, leading to the promotion of apoptosis and autophagy. Further analysis demonstrated that the reduced phosphorylation of mTOR played a significant role in the tumor cell damage caused by pralatrexate. Pralatrexate effectively inhibited the mTOR/4E-BP1 pathway. Activation of mTOR pathway can further obstruct the repressive effect of pralatrexate on gemcitabine-resistant pancreatic cancer. In summary, pralatrexate induces effective inhibition of gemcitabine-resistant pancreatic cancer. This may lead to the expansion of pralatrexate's application and offer benefit to gemcitabine-resistant pancreatic cancer patients in the future.

Spontaneous perforation and intraabdominal abscess due to Meckel's diverticulum revealed on SPECT/CT with 99m-technetium pertechnetate: A case report.

RATIONALE: Meckel's diverticulum (MD) is common congenital abnormality of gastrointestinal tract, only about 6.4% of patients become symptomatic. A smaller minority develop potential fatal complications such as hemorrhage, perforation, abscess, and bowel obstruction. PATIENT CONCERNS: A 15-year-old boy with history of appendicitis was admitted due to worsening abdominal pain and nausea for 1 day. The physical examination showed the abdomen was soft, with the diffuse tenderness to palpation and voluntary guarding. DIAGNOSIS: Abdominal computed tomography showed a probable MD in the distal ileum. Single photon emission computed tomography/computed tomography (SPECT/CT) fusion imaging revealed the focal concentration at the right lower quadrant of abdomen region. INTERVENTION: After the initial management including antibiotic administration and intravenous fluid resuscitation, MD with perforation and localized suppurative peritonitis was confirmed in surgery. The patient underwent a diverticulectomy. Histological examination was confirmed as MD with focal heterotopic gastric tissue. OUTCOMES: After surgery, the patient had uneventful recovery during 3 months follow-up. LESSONS: Spontaneous perforation and intraabdominal abscess due to MD is very rare. Accurate diagnosis of MD remains challenging as clinical symptoms from these complications occur nonspecifically. SPECT/CT fusion imaging is critical for prompt recognition and accurate diagnosis in the successful management of this rarely life-threating complication.

Iodine-125 interstitial brachytherapy reduces tumor growth via Warburg effect inhibition in non-small cell lung cancer A549 ×enografts.

Iodine-125 interstitial brachytherapy (125I-IBT) is an alternative and effective treatment option for unresectable non-small cell lung cancer (NSCLC), and the Warburg effect is a determinant of tumor growth. The present study aimed to explore the influence of 125I-IBT on tumor growth and the Warburg effect, and the potential mechanisms underlying NSCLC progression. Mice with A549 cell xenografts were evenly divided into a control group without 125I-IBT, and three treatment groups receiving 125I-IBT with 20, 40 and 60 Gy. Tumor volume (TV), maximum standardized uptake value (SUVmax) determined by 18F-fluorodeoxyglucose (18F-FDG) micro-positron emission tomography/computed tomography and mean optical density (MOD) of mammalian target of rapamycin (mTOR), c-Myc, hypoxia inducible factor-1α (HIF-1α) and glucose transporter 1 (GLUT1) staining were compared among groups. Tumor inhibition rate (TIR), 18F-FDG uptake attenuation rate (FUAR) and expression suppression rate (ESR) were also calculated on day 14 and 28. The results demonstrated that the mean TV in the 60 and 40 Gy groups was smaller compared with the control TVs since days 14 and 16, respectively. The mean SUVmax value of the 60 Gy group at day 14, and all treatment group SUVmax values at day 28 were lower compared with the controls. In addition, the MOD of mTOR and GLUT1 was lower in the 60 Gy group, compared with the other groups, and c-Myc and HIF-1α values were lower in the 40 and 60 Gy groups, compared with the control and 20 Gy group (P<0.05). SUVmax positively correlated to TV (day 14, r=0.711; day 28, r=0.586) and the MOD of c-Myc and GLUT1 (r=0.621 and 0.546, respectively; P<0.01). Furthermore, dose dependent increases were observed for TIR, FUAR and ESR. In conclusion, 125I-IBT reduced tumor growth by inhibiting the Warburg effect, which may have resulted from downregulation of mTOR, c-Myc, HIF-1α and GLUT1 expression, particularly c-Myc and GLUT1, in NSCLC A549 ×enografts.

A PRISMA-compliant systematic review and meta-analysis of the relationship between thyroid disease and different levels of iodine intake in mainland China.

BACKGROUND: Low-iodine intake has historically been an issue in China, causing widespread iodine deficiency diseases (IDD). China started to introduce universal salt iodization in 1995, but reports of increased thyroid disease are a concern and appropriate levels of iodine intake must be considered. OBJECTIVE: To assess the prevalence of thyroid disease with different urinary iodine concentrations (UICs) in the general population of those residing in mainland China. Furthermore, we aimed to analyze the relationship between thyroid disease and UIC, to provide guidance in establishing effective health policies regarding iodine intake. METHODS: PubMed, Cochrane, Embase, CNKI, Wan fang, and CQVIP databases were searched for random community-based relevant studies with UIC published before January 2016 in mainland China. Two independent reviewers extracted data from eligible citations, and obtained prevalence of thyroid disease for different UICs, as well as the intergroup interaction P values. RESULTS: Forty-three articles were included. The prevalence of thyroid nodules was 22.3% (95% confidence interval [CI]: 20.6%-24.1%) for the low-iodine group, 25.4% (95% CI: 20.8%-28.8%) for the medium-iodine group, and 6.8% (95% CI: 2.8%-11.5%) for the high-iodine group. In the high-iodine group, the prevalence of thyroid nodules was lower than the other groups. The prevalence of 8.3% (95% CI: 3.8%-17.3%) for subclinical hypothyroidism in the high-iodine group was significantly higher than the low- and medium-iodine groups (P < .01). The prevalence of hypothyroidism in the medium-iodine group was 0.2% (95% CI: 0.1%-0.4%), and was lower than the prevalence of the other 2 groups (P < .01). There was no difference in prevalence of hyperthyroidism in each group. CONCLUSIONS: Thyroid nodules are the most easily detectable thyroid disease. These have a lower prevalence in the high-iodine group. The prevalence of most thyroid diseases is lowest for a UIC ranging from 100 to 299 µg/L. This serves as a reference for health policy-making with respect to iodine levels. Further studies on this topic should be carried out according to sufficient thyroid cancer data.

Clinical Characteristics and Outcomes of Propylthiouracil-Induced Antineutrophil Cytoplasmic Antibody-Associated Vasculitis in Patients with Graves' Disease: A Median 38-Month Retrospective Cohort Study from a Single Institution in China.

BACKGROUND: This study sought to investigate the clinical characteristics and outcomes of propylthiouracil (PTU)-induced antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis in patients with Graves' disease. METHODS: Sixteen patients diagnosed with PTU-induced ANCA-associated vasculitis at the authors' hospital from January 2010 to June 2017 were analyzed retrospectively. RESULTS: All 16 patients with PTU-induced ANCA-associated vasculitis were female. The mean age ± standard deviation of the patients was 39.4 ± 15.3 years (range 19-69 years), and the median time of onset was 36 months (range 1-193 months) post-PTU initiation. The median dose at the onset of PTU-induced ANCA-associated vasculitis was 150 mg/day (range 50-300 mg/day). All patients had a positive serum perinuclear staining pattern (p-ANCA) and antibodies directed against myeloperoxidase (anti-MPO). Six patients tested positive for both anti-MPO antibodies and antibodies directed against proteinase-3. Seven (43.8%) patients presented with involvement of a single organ. The kidney was the organ most commonly affected, as 12 (75%) patients were found to have disease involving this organ. PTU was stopped in all patients, corticosteroids were administered to two patients, and immunosuppressive agents and corticosteroids were administered to five patients. Three patients were lost to follow-up. However, the remaining patients achieved remission after a median follow-up period of 38 months (range 6-76 months). Patients who were positive for pANCA and displayed cytoplasmic staining showed negative findings at rates of approximately 53.8% (7/13) and 100% (6/6), respectively, following treatment. CONCLUSIONS: PTU-induced ANCA-positive vasculitis occurs at varying times and after exposure to various doses of PTU. The condition has a milder course and has a better prognosis after PTU cessation.

Characteristics of Antithyroid Drug-Induced Agranulocytosis in Patients with Hyperthyroidism: A Retrospective Analysis of 114 Cases in a Single Institution in China Involving 9690 Patients Referred for Radioiodine Treatment Over 15 Years.

BACKGROUND: Antithyroid drug (ATD)-induced agranulocytosis is a rare but life-threatening disease. Clinical features of ATD-induced agranulocytosis and outcomes remain incompletely understood. METHOD: Patients with clinically diagnosed ATD-induced agranulocytosis were retrospectively studied, involving 9690 patients who were referred for radioiodine treatment during a 15-year period (2000-2015) in China. There were 114 cases of agranulocytosis attributable to ATD included, and their clinical characteristics and therapy outcomes were analyzed. RESULTS: The female-to-male ratio of ATD-induced agranulocytosis was 10.4:1. The mean age (±standard deviation) of the patients with ATD-induced agranulocytosis was 41.7 ± 12.3 years. The methimazole and propylthiouracil doses given at the onset were 22.9 ± 8.0 mg/day and 253.6 ± 177.5 mg/day, respectively. ATD-induced agranulocytosis occurred in 45.1%, 74.3%, and 88.5% of patients within 4, 8, and 12 weeks of the onset of ATD therapy, respectively. Fever (78.9%) and sore throat (72.8%) were the most common symptoms when agranulocytosis was diagnosed. The mean recovery time of agranulocytosis was 13.41 ± 7.14 days. Recovery time in the granulocyte colony-stimulating factor (G-CSF)-treated group (12.7 ± 6.0 days) did not differ from that in the group not treated with G-CSF (16.4 ± 10.6 days; p = 0.144). Treatment with (131)I was successful in 87/98 patients (88.8%). The success rate of (131)I was equivalent (p = 1.000) between the groups receiving methimazole (88.2%, 75/85) and propylthiouracil (92.3%, 12/13). CONCLUSIONS: This largest single-institution study in China shows that ATD-induced agranulocytosis tends to occur within the first 12 weeks after the onset of ATD therapy. For patients with ATD-induced agranulocytosis, G-CSF does not improve the recovery time of agranulocytosis, and (131)I is an optimal treatment approach.

Kikuchi-Fujimoto disease associated with Sjogren's syndrome: a case report and review of the literature.

Kikuchi-Fujimoto disease (KFD), known as subacute necrotizing histiocytic lymphadenitis, is an extremely rare, benign and self-limited disease, and has been infrequently reported with autoimmune diseases. Here we report a 17-year-old girl pathologically diagnosed as KFD who suffered recurrence of KFD and developed into Sjogren's syndrome (SS) after four years and then performed a systematic literature search about KFD associated with SS in which seven patients was reviewed in detail. The results show that SS may be prior to, simultaneous with or following KFD and it developed mainly in young (average age: 25 years), female patients (4/5) after KFD with an average latency of 43 months. Therefore, long follow-up and appropriate clinical and laboratory workup are highly encouraged to exclude underlying SS conditions in young women with KFD.

Unusual Synchronous Methimazole-Induced Agranulocytosis and Severe Hepatotoxicity in Patient with Hyperthyroidism: A Case Report and Review of the Literature.

Context. To report a patient with hyperthyroidism who developed concurrent occurrence of agranulocytosis and severe hepatotoxicity after taking methimazole (MMI). Case. A 51-year-old Chinese male was diagnosed as hyperthyroidism with normal white blood count and liver function. After 4 weeks' treatment with MMI 20 mg/d, it developed to agranulocytosis and severe cholestatic hepatotoxicity. The patient's symptoms and laboratory abnormalities disappeared after the withdrawal of MMI; his white blood count and liver function recover to normal in 2 weeks and 5 weeks, respectively. 296 MBq dose of (131)I was given to the patient 3 weeks after the withdrawal of MMI and his thyroid function was back to normal in 6 months. As we know through literature review, only 5 previous cases reported the synchronous ATD-induced agranulocytosis and severe hepatotoxicity in patients with hyperthyroidism. Methods. Review of the patient's clinical course. Literature review of cases of hyperthyroidism with agranulocytosis and severe hepatotoxicity demonstrated that these complications occurred after taking antithyroid drug (ATD). Conclusions. Patient with hyperthyroidism can have synchronous ATD-induced agranulocytosis and severe hepatotoxicity. This case is extremely rare, but the adverse effects with ATDs is clinically significant. The clinicians need to be careful about this and monitor biochemical of patients who take ATDs.

(18)F-Fluorodeoxyglucose positron emission tomography/computed tomography in patients with Kikuchi-Fujimoto disease: a nine-case series in China.

This study observed the image characteristics and clinico-imaging relationships of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the patients with Kikuchi-Fujimoto disease (KFD). Nine consecutive patients with histologically proven KFD who underwent (18)F-FDG PET/CT were recruited. The (18)F-FDG uptakes of bone marrow (BM), spleen and lymph nodes (LNs) were systematically evaluated and maximum standardized uptake values (SUVmax) were measured. The number, locations and size factors of LNs were also assessed. The correlations were calculated between (18)F-FDG uptake and laboratory data and size factors of LNs, and the findings of LNs were compared between subgroups with different clinical features. (18)F-FDG uptakes were positive in the BM (SUVmax, 3.2 ± 1.2), spleen (SUVmax, 2.8 ± 0.7) and 122 affected LNs (SUVmax, 4.2 ± 2.2) for all patients. The affected LNs presented a systemically (region, 4 ± 1), multiple (number, 14 ± 5) and small-sized (long axis diameter, 11.4 ± 2.7 mm; short axis diameter, 8.0 ± 2.1 mm; area, 81.1 ± 44.6 mm(2)) pattern. The SUVmax of BM correlated to neutrophil count, and the SUVmax of affected LNs correlated to size factors and was lower in patients with long imaging interval and positive anti-nuclear antibody (ANA) (P < 0.05). We conclude that (18)F-FDG PET/CT can be characterized by the generalized distribution of relatively small-sized LNs and involvement of BM and spleen with high (18)F-FDG avidity in patients with KFD. The imaging interval, neutrophil count and ANA level should be synthetically considered during imaging evaluation.

Analysis of 90 cases of antithyroid drug-induced severe hepatotoxicity over 13 years in China.

BACKGROUND: Antithyroid drug (ATD)-induced severe hepatotoxicity is a rare but serious complication of ATD therapy. The characteristics of severe hepatotoxicity have been reported in only a small number of patients. METHOD: Ninety patients with ATD-induced severe hepatotoxicity presenting during a 13 year period (2000-2013) who were about to undergo nuclear medicine therapy with (131)I from a sample of 8864 patients with hyperthyroidism were studied, and the outcomes were evaluated. RESULTS: The mean age of the patients with ATD-induced severe hepatotoxicity was 41.6±12.5 years (mean±standard deviation), and the female to male ratio was 2.2:1. The methimazole (MMI) dose given at the onset was 19.1±7.4 mg/day. The propylthiouracil (PTU) dose given at the onset was 212.8±105.0 mg/day. ATD-induced severe hepatotoxicity occurred in 63.3%, 75.6%, and 81.1% of patients within 4, 8, and 12 weeks of the onset of ATD therapy, respectively. The types of severe hepatotoxicity did not differ significantly between the MMI and PTU groups (p=0.188). The frequency of the cholestatic type in the MMI group (35.3%, 18/51) was higher than that in the PTU group (17.9%, 7/39), but these frequencies were not significantly different (p=0.069). The patients who were treated with (131)I received an average dose of 279.1±86.1 MBq (n=84). Therapy was successful in 60 of the 67 patients (89.6%). The success rate was equivalent (p=0.696) between the groups receiving MMI (91.7%, 33/36) and PTU (87.1%, 27/31). CONCLUSIONS: Severe hepatotoxicity tends to occur within the first three months after the onset of ATD therapy. The type of ATD-induced severe hepatotoxicity did not differ between the MMI and PTU groups. (131)I therapy is an effective treatment approach for patients with ATD-induced severe hepatotoxicity.

Unusual synchronous skeletal muscle and lung metastasis in papillary thyroid cancer: A case report and review of the literature.

Papillary thyroid cancer (PTC) frequently metastasizes to the cervical lymph region and less often to the lung and bone. Metastasis to the skeletal muscles from PTC is extremely rare, especially concurrent lung and skeletal muscle metastases. The present study reports the case of a 31-year-old man with synchronous metastasis to the skeletal muscle and lung from PTC, six years following total thyroidectomy and consecutive 131Iodine treatments. Magnetic resonance imaging (MRI) revealed a 1.7×1.2×1.5 cm mass in the left gastrocnemius muscle, indicating a neurogenic tumor. The mass was subsequently resected and confirmed via histopathology to be metastatic PTC. We propose that, in the follow-up of patients with PTC, the measurable serum thyroglobulin level, whole body scan and other imaging modalities including MRI or positron emission tomography/computed tomography, must be closely monitored for potential distant metastases, particularly in cases of PTC with aggressive pathological behavior.

Diagnostic performance of 18F-FDG-PET versus scintigraphy in patients with inflammatory bowel disease: a meta-analysis of prospective literature.

OBJECTIVE: The aim of this study was to evaluate the diagnostic performance of fluorine-18 fluorodeoxyglucose-PET (F-FDG-PET), leukocyte scintigraphy (LS), and monoclonal antigranulocyte antibody scintigraphy (MAAS) in patients with inflammatory bowel disease (IBD) and perform pairwise comparisons of the diagnostic accuracy between these different imaging modalities. METHODS: Through a search of PubMed, EMBASE, and the Cochrane Library (January 1993-May 2013), we performed a random effects meta-analysis and constructed summary receiver operating characteristic curves on per-bowel-segment or per-patient basis. Two-sample Z-tests were performed to evaluate differences in sensitivity, specificity, area under the curve (AUC), and the Q* index between any two diagnostic modalities on per-bowel-segment basis. RESULTS: Twenty prospective studies were reviewed. On per-bowel-segment basis, the F-FDG-PET had a pooled sensitivity of 0.84, specificity of 0.86, AUC of 0.913, and Q* index of 0.845, whereas for LS, the corresponding values were 0.79, 0.86, 0.877, and 0.808, respectively, and for MAAS they were 0.45, 0.94, 0.524, and 0.518, respectively. On per-patient basis, the corresponding values of LS were 0.91, 0.85, 0.937, and 0.874, respectively. Statistically significant differences were not found in the sensitivity, specificity, AUC, and Q* index between F-FDG-PET and LS on per-bowel-segment basis. CONCLUSION: F-FDG-PET has a high degree of diagnostic performance compared with LS and MAAS on per-bowel-segment basis in patients with IBD. LS may be used with satisfactory diagnostic accuracy in detecting active IBD when PET systems are unavailable. A larger prospective validation of these findings would be valuable.

A systematic review of MRI, scintigraphy, FDG-PET and PET/CT for diagnosis of multiple myeloma related bone disease--which is best?

AIM: The purpose of the current study was to conduct a systematic review of the published literature to evaluate the diagnostic accuracy of FDG-PET, PTE/CT, MRI and scintigraphy for multiple myeloma related bone disease. METHODS: Through a search of PubMed, EMBASE, and the Cochrane Library, two reviewers independently assessed the methodological quality of each study. We estimated pooled sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR), and two sample Z-tests were conducted to evaluate for differences in sensitivity, specificity, area under the curve (AUC), and the Q* index between any two diagnostic modalities. RESULTS: A total of 17 studies were reviewed. The MRI had a pooled sensitivity of 0.88, specificity of 0.68, AUC of 0.897, and Q*index of 0.828, whereas for MIBI, the corresponding values were 0.98, 0.90, 0.991, and 0.962, respectively, and for bone scan, they were 066, 0.83, 0.805, and 0.740, respectively. The corresponding values of MIBI were 0.98, 0.90, 0.991, and 0.962, respectively. For PET and PET/CT, the values were 0.91, 0.69, 0.927 and 0.861, respectively. Statistically significant differences were not found in the sensitivity, specificity, AUC, and Q* index between MRI, scintigraphy, FDG-PET and PET/CT. CONCLUSIONS: On the condition that X ray is taken as a reference in our study, we suggested that FDG-PET, PTE/CT, MRI and scintigraphy are all associated with high detection rate of bone disease in patients with MM. Thus, in clinical practice, it is recommended that we could choose these tests according to the condition of the patient.

[Molecular mechanism of radiosensitizing effect of paclitaxel].

BACKGROUND & OBJECTIVE: Paclitaxel is a radiosensitizer which may stabilize microtubules, block the G2/M phase of the cell cycle and thus modulate the radioresponsiveness of tumor cells. However, its potential molecular mechanisms of radiosensitization have not been well understood yet. This study was to investigate the radiosensitizing effect of paclitaxel on human oral epithelium carcinoma (KB) cell line and to explore the molecular mechanism of radiosensitization. METHODS: The survival of KB cells following the treatment with paclitaxel and/or radiation was determined by colony-forming assay. The radiosensitizing effect was evaluated by calculating the sensitizing enhancement ratio (SER) with multi-target single hit model. The cell cycle distribution was analyzed by flow cytometry. Differentially expressed genes related to paclitaxel radiosensitization were screened using human Oligo microarray. Expressions of protein regulating cytokinesis 1 (PRC1) and cyclin B2 genes were confirmed by real-time quantitative PCR. RESULTS: The proliferation of KB cells was significantly inhibited by paclitaxel combined with ionizing radiation. The SERD0 and SERDq were (2.40 +/- 1.87) and (12.23 +/- 2.81) respectively, when the concentration of paclitaxel was 20 nmol/l. After the treatment with paclitaxel in combination with irradiation, the percentage of G1 phase cells decreased from (48.32 +/- 2.40)% to (15.73 +/- 7.00)% (P<0.01), and the percentage of G2/M phase cells increased from (13.66 +/- 2.16)% to (52.51 +/- 5.02)% (P<0.01). In total 176 differentially expressed genes were identified to be related to paclitaxel radiosensitization. Ten genes were found to regulate cell division, two of which were up-regulated and eight were down-regulated after the treatment. Moreover, the expression of PRC1 and cyclin B2 was decreased. CONCLUSION: The radiosensitizing effect of paclitaxel on KB cells may be due to the down-regulated expression of PRC1 and cyclin B2, resulting in inhibition of mitotic spindle formation and cell necrosis.