Mechanism of ERBB2 gene overexpression by the formation of super-enhancer with genomic structural abnormalities in lung adenocarcinoma without clinically actionable genetic alterations.

BACKGROUND: In an extensive genomic analysis of lung adenocarcinomas (LUADs), driver mutations have been recognized as potential targets for molecular therapy. However, there remain cases where target genes are not identified. Super-enhancers and structural variants are frequently identified in several hundred loci per case. Despite this, most cancer research has approached the analysis of these data sets separately, without merging and comparing the data, and there are no examples of integrated analysis in LUAD. METHODS: We performed an integrated analysis of super-enhancers and structural variants in a cohort of 174 LUAD cases that lacked clinically actionable genetic alterations. To achieve this, we conducted both WGS and H3K27Ac ChIP-seq analyses using samples with driver gene mutations and those without, allowing for a comprehensive investigation of the potential roles of super-enhancer in LUAD cases. RESULTS: We demonstrate that most genes situated in these overlapped regions were associated with known and previously unknown driver genes and aberrant expression resulting from the formation of super-enhancers accompanied by genomic structural abnormalities. Hi-C and long-read sequencing data further corroborated this insight. When we employed CRISPR-Cas9 to induce structural abnormalities that mimicked cases with outlier ERBB2 gene expression, we observed an elevation in ERBB2 expression. These abnormalities are associated with a higher risk of recurrence after surgery, irrespective of the presence or absence of driver mutations. CONCLUSIONS: Our findings suggest that aberrant gene expression linked to structural polymorphisms can significantly impact personalized cancer treatment by facilitating the identification of driver mutations and prognostic factors, contributing to a more comprehensive understanding of LUAD pathogenesis.

Impact of 18F-FDG PET on TNM Staging and Prognosis in Thymic Epithelial Tumors.

BACKGROUND: Preoperative fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET) of thymic epithelial tumors (TETs) is well known for identifying malignant-grade TETs; however, its predictive power for determining locally advanced tumors, lymph node (LN) metastasis, and prognosis remains unknown. PATIENTS AND METHODS: We retrospectively evaluated patients with resectable TETs who were preoperatively assessed using 18F-FDG PET from January 2012 to January 2023. The receiver operating characteristic curve was used to evaluate the cutoff value of the maximum standardized uptake value (SUVmax) to predict advanced-stage disease. Recurrence/progression-free survival (RFS/PFS) was analyzed using the Kaplan-Meier method. The staging was classified according to the tumor-node-metastasis system. RESULTS: Our study included 177 patients; 145 (81.9%) had pathological early-stage TET (stage I or II), and 32 (19.1%) had advanced stage (stage III or IV). The area under the curve value for predicting the advanced stage was 0.903, and the cutoff value was 5.6 (sensitivity 81.3%, specificity 84.8%). SUVmax > 5.6 was associated with worse prognosis for RFS/PFS. LN metastasis was preoperatively detected by FDG uptake in 30.8% of patients with pathological LN positivity, whereas LN metastasis was not pathologically detected in patients with SUVmax < 5.9. In patients with advanced-stage TETs, LN recurrence was more frequent in patients who were preoperatively detected by 18F-FDG PET than those who were not (75.0% versus 7.1%). CONCLUSIONS: 18F-FDG PET is a potentially valuable tool for predicting advanced stage and poor prognosis of recurrence in patients with TETs. SUVmax can help thoracic surgeons to guide them in selecting appropriate therapeutic strategies for TETs.

Nivolumab-induced radiation recall pneumonitis in non-small-cell lung cancer patients with thoracic radiation therapy.

The role of previous thoracic radiation therapy as a risk factor of immune-related pneumonitis is unclear. Furthermore, some patients develop radiation recall pneumonitis, which is characterized by a radiation pneumonitis-like imaging pattern with consolidation progressing within a previous radiation field. In this multicenter retrospective study, we analyzed the relationship of previous thoracic radiation therapy with immune-related pneumonitis and the characteristics of radiation recall pneumonitis. The medical records of patients with non-small-cell lung cancer who had received nivolumab between December 2015 and March 2017 at five institutions were retrospectively reviewed. Incidence, imaging patterns, clinical course, and risk factors of immune-related pneumonitis and radiation recall pneumonitis were evaluated. A total of 669 patients were evaluated, and the incidences of all-grade and grade 3 or higher immune-related pneumonitis were 8.8% and 2.6%, respectively. The incidences of immune-related pneumonitis were 13.2% (34/257) and 6.1% (25/412) in patients with and those without previous thoracic radiation therapy, respectively. A history of previous thoracic radiation therapy was associated with immune-related pneumonitis (odds ratio, 2.11; 95% confidence interval, 1.21-3.69 in multivariate analysis). Among the patients with previous thoracic radiation therapy, 6.2% (16/257) showed radiation recall pattern. This study found an increased risk of nivolumab-induced immune-related pneumonitis associated with a history of thoracic radiation therapy. Radiation recall pattern was one of the major patterns of immune-related pneumonitis among the patients with previous thoracic radiation therapy. Incidence, risk factors, and clinical outcome of radiation recall pneumonitis were elucidated.

Prediction model for nonopiate-induced neonatal abstinence syndrome.

BACKGROUND: Neonatal abstinence syndrome (NAS) induced by opiate use is common worldwide. Psychiatric drugs are a more common cause of NAS in Japan but infants of mothers taking psychiatric medications do not always develop NAS. The purpose of this study was to develop a practical model for predicting the onset of nonopiate-induced NAS, using variables available at birth. METHODS: In this diagnostic study, prediction models were developed using multivariable logistic regression with retrospective data collected at our hospital between 2010 and 2019. The NAS diagnosis was based on the Isobe score, and maternal medications were converted to dose equivalents. RESULTS: A total of 164 maternal and infant dyads met the inclusion criteria; 91 were included in the analysis, of whom 29 infants (32%) were diagnosed with NAS. Final models were created with and without the drug indices. The model without the drug indices consisted of neonatal head circumference in z-scores and Apgar scores at 5 min < 9, and the model with the drug indices included these, as well as antipsychotics and hypnotics indices. The C-statistics were 0.747 (95% CI: 0.638-0.856), and 0.795 (95% CI: 0.683-0.907), respectively, indicating that the models possessed good predictive accuracy for NAS onset. CONCLUSIONS: This study developed models that predicted nonopiate-induced NAS accurately. They may be further improved through the use of drug indices.

Tumor size in patients with severe pulmonary emphysema might be underestimated on preoperative CT.

OBJECTIVES: To evaluate the effect of emphysema on tumor diameter measured on preoperative computed tomography (CT) images versus pathological specimens. MATERIALS AND METHODS: We investigated patients who underwent primary lung cancer surgery: 55 patients (57 tumors) with severe emphysema and 57 patients (57 tumors) without emphysema. The tumor diameters measured in the postoperative pathological specimens were compared with those measured on the axial CT images and on multiplanar reconstruction (MPR) CT images by two independent radiologists; a subgroup analysis according to tumor size was also performed. A paired or unpaired t test was performed, depending on the tested subjects. RESULTS: In the emphysema group, the mean axial CT diameter was significantly smaller than the mean pathological diameter (p = 0.025/0.001 for reader 1/2), whereas in the non-emphysema group, the mean axial CT diameter was not significantly different from the pathological one for both readers. The difference between CT axial diameter and pathological diameter (= CT diameter - pathological diameter) was significantly smaller (i.e., had a stronger tendency toward underestimation on radiological measurements) in the emphysema group compared with the non-emphysema group (p = 0.014/0.008 for reader 1/2), and the difference was significantly smaller in tumors sized > 30 mm than tumors sized ≤ 20 mm in both groups. CONCLUSIONS: Tumor size is significantly smaller on preoperative CT in patients with severe emphysema compared to patients without emphysema, especially in the case of large tumors. MPR measurement using the widest of three dimensions should be used to select T-stage for patients with severe emphysema. KEY POINTS: • The presence of emphysema affects the accuracy of tumor size measurements on CT. • Compared to patients without emphysema, the tumor size in severe emphysema patients tends to be measured smaller in preoperative CT than the pathological specimen. • This trend is more evident when large tumors are measured on axial CT images alone.

Assessment of Resectability of Mediastinal Germ Cell Tumor Using Preoperative Computed Tomography.

BACKGROUND AND OBJECTIVES: Mediastinal germ cell tumor (MGCT) is a relatively rare tumor. Complete resection after chemotherapy is a standard treatment against this disease. However, the risk factors of incomplete resection are unclear. Therefore, we analyzed survival rates and risk factors for incomplete resection based on preoperative imaging. METHODS: We retrospectively reviewed the medical records of patients (n = 56) with MGCT operated at National Cancer Center Hospital, and analyzed preoperative computed tomography (CT) data in terms of relationship of the tumor and vessels, and investigated survival rate and risk factors for incomplete resection. RESULTS: A total of 56 patients underwent resection of MGCT. The 5-y progression-free survival (PFS) and overall survival (OS) were 79% and 83%. In multivariate analysis, complete resection was the only significant prognostic factor for better PFS (hazard ratio (HR) = 9.083, P= 0.00021) and OS (HR = 5.519, P= 0.0445). The preoperative CT finding of arteries (including the aorta, right brachiocephalic artery, left common carotid artery, and left subclavian artery) surrounded by the tumor was a predictor of incomplete resection (odds ratio = 10.089, P= 0.049). CONCLUSIONS: Complete resection is essential for improving the survival of MGCT, and the risk stratification using preoperative CT imaging brings important information to achieve the complete resection.

Aggressive histological component in subsolid lung adenocarcinoma: priority for resection without delay.

INTRODUCTION: This study explored the predictors of a histological aggressive component in ground glass opacity-containing lung adenocarcinoma. METHODS: Of the 2388 patients who underwent resection for lung cancer at our institute between 2017 and 2020, we collected data on the 501 patients with ground glass opacity-containing adenocarcinoma with a total diameter of ≤2 cm. Using a historical cohort, we identified histological aggressive components that were related to a poor prognosis in early-stage adenocarcinoma. A multivariable analysis was conducted to identify predictors for the presence of a histological aggressive component. RESULTS: Lymphovascular invasion and predominant micropapillary or solid patterns were identified as histological aggressive components by a prognostic analysis using a historical cohort. Of the 501 patients included, 36 (7.2%) had at least one histological aggressive component. A multivariate analysis showed that a consolidation/tumour ratio > 0.5 (P < 0.01), maximum standardized uptake value on positron emission tomography ≥1.5 (P = 0.01) and smoking index >20 pack-years (P = 0.01) were predictors of the presence of a histological aggressive component. A total of 98% of cases without any of the above factors did not have a histological aggressive component. CONCLUSIONS: Approximately 7% of ground glass opacity-containing small adenocarcinomas contained histological aggressive component. A consolidation/tumour ratio > 0.5, maximum standardized uptake value ≥ 1.5 and smoking index >20 pack-years were predictors for such cases. These predictors may be useful for screening patients with a potentially high risk of a poor prognosis and for prioritizing resection without delay.

Head circumference in infants with nonopiate-induced neonatal abstinence syndrome.

BACKGROUND: No relationship has been reported between nonopiate neonatal abstinence syndrome (NAS) and anthropometric indices, including head circumference (HC). The purpose of this study was to determine the relationship between maternal nonopioid drug use and HC at birth in neonates with NAS. METHODS: This retrospective observational study included neonates born between January 1, 2010 and March 31, 2019, whose mothers had been taking antipsychotic, antidepressant, sedative, or anticonvulsant medications. The outcome measures were HCs of NAS infants and controls. RESULTS: Of 159 infants, 33 (21%) were diagnosed with NAS. There was no maternal opioid use among mothers during pregnancy. The HCs in the NAS group were significantly smaller than those in the control group. The median z-scores for HC at birth were -0.20 and 0.29 in the NAS group and the control group, respectively (P = .011). The median HCs at birth were 33.0 and 33.5 cm in the NAS group and the control group, respectively. Multivariate analysis revealed that maternal antipsychotic drug use and selective serotonin reuptake inhibitors were independently associated with NAS (P < .001 and P = .004, respectively). Notably, benzodiazepine use and smoking were not independent risk factors. CONCLUSIONS: The results suggest an association between maternal antipsychotic drug use and NAS, which was further associated with decreased HC. Careful monitoring of maternal drug use should be considered to improve fetal outcomes.

Adenocarcinoma in situ and minimally invasive adenocarcinoma in lungs of smokers: image feature differences from those in lungs of non-smokers.

PURPOSE: We aimed to examine the characteristics of imaging findings of adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) in the lungs of smokers compared with those of non-smokers. MATERIALS AND METHODS: We included seven cases of AIS and 20 cases of MIA in lungs of smokers (pack-years ≥ 20) and the same number of cases of AIS and MIA in lungs of non-smokers (pack-years = 0). We compared the diameter of the entire lesion and solid component measured on computed tomography (CT) images, pathological size and invasive component diameter measured from pathological specimens, and CT values of the entire lesion and ground-glass opacity (GGO) portions between the smoker and non-smoker groups. RESULTS: The diameters of AIS and MIA on CT images and pathological specimens of the smoker group were significantly larger than those of the non-smoker group (p = 0.036 and 0.008, respectively), whereas there was no significant difference in the diameter of the solid component on CT images or invasive component of pathological specimens between the two groups. Additionally, mean CT values of the entire lesion and GGO component of the lesions in the smoker group were significantly lower than those in the non-smoker group (p = 0.036 and 0.040, respectively). CONCLUSION: AIS and MIA in smoker's lung tended to have larger lesion diameter and lower internal CT values compared with lesions in non-smoker's lung. This study calls an attention on smoking status in CT-based diagnosis for early stage adenocarcinoma.

Surgical Results in Pathological N1 Nonsmall Cell Lung Cancer.

BACKGROUND: This retrospective study investigated the prognosis of patients with pathological N1 (pN1) nonsmall cell lung cancer (NSCLC). METHODS: We included patients with pN1 NSCLC who underwent lobectomy or pneumonectomy with mediastinal lymph node dissection and achieved complete resection (R0) between January 2000 and December 2012. Patients who received neoadjuvant therapy were excluded. RESULTS: A total of 249 patients were included. The mean age was 63.2 years, and 172 patients were males. Of the 249 patients, 200, 20, and 29 underwent lobectomy, bilobectomy, and pneumonectomy, respectively. The median observation period was 5.5 years. The 5-year overall survival (OS) rate was 64.6% (95% confidence interval: 58.3-70.4). Five-year OS rates were 79.8% for positive lymph nodes at station 13 or 14 (n = 57), 59.6% at station 12 (n = 72), 62.7% at station 11 (n = 69), and 56.9% at station 10 (n = 51) (log-rank test; p = 0.016); furthermore, the 5-year OS rate was 75.2% for patients with positive lymph nodes at a single station (n = 160) and 45.4% for patients with positive lymph nodes at multiple stations (n = 89) (log-rank test; p < 0.001). Five-year cumulative incidences of recurrence were equivalent between patients who received adjuvant chemotherapy and patients who did not (45.9 vs. 55.1%; Gray's test; p = 0.366). Distant recurrence was the most frequent mode of recurrence in both groups (70.8 and 67.3%). CONCLUSION: The locations and the number of stations of the positive lymph nodes were identified as prognostic factors in patients with pN1 NSCLC. The primary mode of recurrence was distant recurrence irrespective of postoperative adjuvant chemotherapy.

Association Between Eosinophilia and Late-onset Circulatory Collapse in Preterm Infants: A case-Control Study.

Late-onset circulatory collapse (LCC) in preterm infants is presumably caused by relative adrenal insufficiency. Because eosinophilia is known to be associated with adrenal insufficiency, we attempted to clarify the relation-ship between eosinophilia and LCC in preterm infants. We divided the cases of the infants (born at < 28 weeks' gestation) admitted to our neonatal intensive care unit in 2008-2010 into 2 groups: those diagnosed with LCC that received glucocorticoids (LCC group), and those who did not receive glucocorticoids (control group). We compared eosinophil counts between the 2 groups and between before and after glucocorticoid treatment in the LCC group. A total of 28 infants were examined: LCC group (n = 12); control group (n = 16). The peak eosin-ophil counts of the LCC group were significantly higher than those of the control group (median: 1.392 × 109/L vs. 1.033 × 109/L, respectively; p = 0.02). Additionally, in the LCC group, the eosinophil counts declined significantly after glucocorticoid treatment (0.877 × 109/L vs. 0.271 × 109/L, p = 0.003). Eosinophil counts in the LCC group were significantly higher than in the control group and decreased rapidly after gluco-corticoid treatment. These results indicate that eosinophilia may be a factor associated with LCC caused by adrenal insufficiency.

Ciliated Muconodular Papillary Tumor of the Lung: Thin-Section CT Findings of 16 Cases.

OBJECTIVE. The purpose of this article was to assess thin-section CT features of ciliated muconodular papillary tumors (CMPTs) of the lung and correlations between radiologic and pathologic findings. MATERIALS AND METHODS. Thin-section CT findings of 16 patients (10 men and six women; mean age, 70.7 years) with surgically resected CMPTs were retrospectively analyzed. Size, location, and internal characteristics of the tumors were evaluated. The amount of mucin in the tumors was assessed histopathologically and compared with CT findings. Tumor growth speed was calculated on the basis of size changes on thin-section CT. RESULTS. In all 16 patients, tumors were detected as a solitary pulmonary nodule. Thirteen tumors (81.3%) were located in the lower lobes, and 10 (62.5%) were adjacent to the pleura. Mean maximal diameter of the tumors was 9.1 mm (range, 6-14 mm). One tumor (6.3%) presented as a pure ground-glass nodule (GGN), seven (43.8%) as dense GGNs, and eight (50.0%) as solid nodules. Pathologically, the pure GGN and five of seven dense GGNs had a large amount of mucin, whereas seven of eight solid nodules had an intermediate or small amount of mucin. The mean annual tumor growth rate (in diameter) was 0.49 mm/y. CONCLUSION. CMPTs appear as solitary, small, and peripheral pulmonary nodules with very slow growth rates. CMPTs appearing as pure GGNs and dense GGNs tend to contain more mucin than CMPTs appearing as solid nodules.

Is Calcification in the Regional Lymph Nodes a Benign Feature in Patients with Lung Cancer?

BACKGROUND: Calcified lymph nodes (LNs) on computed tomography (CT) in patients with lung cancer are generally considered to be a benign feature. However, few studies have evaluated the pathological status of such calcified LNs. We investigated the clinicopathological findings of patients with calcified LNs on preoperative CT who underwent operation for lung cancer and assessed the frequency of metastasis to calcified LNs as well as the risk factors associated with such metastases. METHODS: This was a retrospective study of 72 consecutive patients with calcified LNs detected on preoperative CT who underwent pulmonary resection for primary lung cancer between 2011 and 2013. A total of 354 LN stations including 101 LN stations with calcified LNs were evaluated. RESULTS: The frequency of metastasis to calcified LNs was 19.4% (14 of 72 patients) on a per-person basis and 18.8% (19 of 101 stations) on a per-nodal station basis. When the size of calcification was major (>5 mm), the frequency of metastasis to such calcified LNs was significantly lower than when it was minor (≦5 mm) on a per-nodal station basis (11.1% vs 27.7%, P = 0.043). Furthermore, when the size of calcification was major and the status of LN stations with calcified LNs was single, there was no metastasis to such LN stations (0 of 26 stations). CONCLUSIONS: The frequency of metastasis to calcified LNs was about 20% on both a per-person and a per-nodal station basis. Although calcified LNs as well as non-calcified LNs should be dissected during operation, dissection of a single LN station with calcification, particularly major calcification, can be omitted.

Population-based longitudinal study showed that children born small for gestational age faced a higher risk of hospitalisation during early childhood.

AIM: We examined the effects of being born small for gestational age (SGA) on the risk of being hospitalised for common diseases during childhood. METHODS: This Japanese nationwide, population-based longitudinal survey followed babies born before 42 weeks of gestation from 10 to 17 January and from 10 to 17 July 2001, using data from the Government's Longitudinal Survey of Babies in the 21st Century. Our study followed 41 268 children until 5.5 years of age: 39 107 full term (8.7% SGA) and 2161 preterm (15.5% SGA). We evaluated the relationship between SGA status and hospitalisation using their history of hospitalisation for common diseases and comparing full-term or preterm births. Logistic regression analysis, adjusted for potential confounders, estimated the odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: The full-term and preterm children who were born SGA were more likely to be hospitalised during infancy and early childhood than those born non SGA. The ORs for hospitalisation from six months to 18 months of age were 1.23 (95% CI: 1.10-1.37) for full-term and 1.67 (95% CI: 1.23-2.25) for preterm subjects. Higher risks of hospitalisation due to bronchitis, pneumonia, bronchial asthma and diarrhoea were also observed. CONCLUSION: Being born SGA was associated with all-cause and cause-specific hospitalisation in early childhood, particularly for term infants.

Small for gestational age is a risk factor for the development of delayed thyrotropin elevation in infants weighing less than 2000 g.

OBJECTIVE: Delayed thyrotropin (TSH) elevation (dTSHe) is common in low birthweight infants. We aimed to clarify the risk factors for the development of dTSHe in infants weighing <2000 g at birth. PATIENTS AND METHODS: According to Japanese guidelines, infants with birthweight <2000 g underwent second capillary TSH screening within 30 days, either at 1 month of age; or when weight reached 2.5 kg; or at discharge. dTSHe was defined as TSH >20 mIU/L by venous sampling following a normal result (<15 mIU/L) at first screening aged 4-6 days. For each infant who developed dTHSe three babies without dTSHe were selected and matched for gestational age and birth year. Small for gestational age (SGA) was defined as a birthweight <10th percentile for the gestational age and sex. A multivariate analysis was performed to identify risk factors for the development of dTSHe. RESULTS: Among the 911 study infants, 17 infants (1.9%) had dTSHe. The median (range) birthweight in the dTSHe group (796 [388-1912] g) was significantly smaller than the comparison group (961 [408-1981] g) (P = 0.04). The number (%) of SGA infants was significantly higher in the dTSHe group (12 [71%]) than in the comparison group (13 [25%]) (P = 0.001). The multivariate analysis revealed that SGA was an independent risk factor for the development of dTSHe (adjusted odds ratio, 9.0; 95% confidence interval, 2.5-32.8; P = 0.001). CONCLUSIONS: Small for gestational age is an independent risk factor for the development of dTSHe in infants with a birthweight <2000 g. The influence of prematurity, a matching criterion for this study, on dTSHe requires additional study.

pH regulates pore formation of a protease activated Vip3Aa from Bacillus thuringiensis.

Vip3Aa insecticidal protein is produced from Bacillus thuringiensis and exerts a broad spectrum of toxicity against lepidopteran insect species. Although Vip3Aa has been effectively used as part of integrated pest management strategies, the mechanism of the toxin remains unclear. Here, we investigated the effect of pH in a range from 5.0 to 10.0 on the pore-forming activity of the trypsin activated Vip3Aa (actVip3Aa) by in vitro pore-forming assays. Based on calcein release assay, actVip3Aa could permeabilize the artificial neutral liposomes under all the pH tested, except pH10.0. The maximum membrane permeability of actVip3Aa was detected at pH8.0 and the permeability decreased and abolished when exposing to acidic and alkaline conditions, respectively. The planar lipid bilayer experiment revealed that actVip3Aa formed ion channels at pH5.0-8.0 but no current signals were detected at pH10.0, consistent with the observation from calcein release assay. The toxin formed ion channels with a diameter of 1.4nm at pH8.0 and pore size was gradually decreased when reducing the pH. This study provided a view of the molecular mechanism of Vip3Aa by which the pore-forming activity is regulated by pH.

Analysis of Pore Formation and Protein Translocation Using Large Biological Nanopores.

This paper describes the analysis of pore formation and detection of a single protein molecule using a large nanopore among five different pore-forming proteins. We demonstrate that the identification of appropriate pores for nanopore sensing can be achieved by classifying the channel current signals and performing noise analysis. Through these analyses, we selected a perforin nanopore from the membrane attack complex/perforin superfamily and attempted to use it to detect the granzyme B protein, a serine protease. As a result, we found that granzyme B might pass through the perforin nanopore if it adopts an unfolded structure. Our proposed analytical approach should be useful for exploring several types of nanopore as large biological nanopores other than α-hemolysin.

Expression and characterization of the Plasmodium translocon of the exported proteins component EXP2.

The malaria parasite Plasmodium falciparum requires the Plasmodium translocon of exported proteins (PTEX) to proliferate in human red blood cells. During the blood stages of malaria, several hundred parasite-encoded proteins are exported from the parasite into the cytosol of red blood cells. PTEX is the translocon for protein export and comprises 5 proteins: EXP2, PTEX150, PTEX88, Hsp101 and TRX2. Among them, EXP2 is thought to constitute the transmembrane pore, whereas the other components seem to play a role in unfolding the luggage proteins or providing a driving force. However, detailed functional and structural characterizations of PTEX proteins have not been performed. In this study, we expressed and characterized the membrane-associated component EXP2. Because expression of EXP2 is lethal to E. coli, EXP2 was expressed as a fusion protein with GST, and the recombinant EXP2 was obtained by protease digestion. The recombinant EXP2 formed pores in bilayer lipid membranes. The inner diameter of the pore was estimated to be approximately 3.5 nm based on electron microscopy images and channel currents. From this size and the molecular mass as determined by size exclusion chromatography and blue native polyacrylamide gel electrophoresis, we determined that the pore comprises approximately 10-12 EXP2 subunits. However, there is a possibility that the pore structure is different in the PTEX complex. These results provide important insights in the protein transport mechanism of PTEX, which will aid in developing new drugs targeting PTEX.

Positive Minimal Residual Disease of FLT3-ITD before Hematopoietic Stem Cell Transplantation Resulted in a Poor Prognosis of an Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) patients with fms-related tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD) often have a poor prognosis, even after hematopoietic stem cell transplantation (HSCT). We report a case of AML with FLT3-ITD identified upon initial diagnosis, who received HSCT at complete remission after 3 consecutive chemotherapies. However, the patient relapsed when the same FLT3-ITD clone emerged, and finally died. Retrospective analysis revealed an allelic ratio of FLT3-ITD/wild type of 1.1 and 0.0096 upon initial diagnosis and before HSCT, respectively. The detection of any minimal residual FLT3-ITD clone before HSCT is useful in the treatment of AML with FLT3-ITD.