Independent Assessment of the Children's Hepatic Tumors International Collaboration Risk Stratification for Hepatoblastoma and the Association of Tumor Histological Characteristics With Prognosis.

Importance: Hepatoblastoma is the most common pediatric liver malignant neoplasm, and accurate risk stratification is essential for guiding treatment. Objective: To validate the Children's Hepatic Tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) in an independent cohort of patients with hepatoblastoma and evaluate the association of pretreatment hepatoblastoma histological subtype with prognosis. Design, Setting, and Participants: This is a single-institution retrospective cohort study of 96 pediatric patients with hepatoblastoma diagnosed and treated between June 1, 2000, and December 31, 2016, with recent therapy and independent of the CHIC-HS discovery cohort. Each patient was assigned a risk group according to CHIC-HS. The histological characteristics of each tumor were assessed based on the International Pediatric Liver Tumor Consensus Classification. Data were analyzed from May 2018 to May 2019. Main Outcomes And Measures: The main outcomes were event-free survival (EFS) and overall survival (OS). Cox regression analysis was used to examine the associations of patient characteristics and tumor histological characteristics with survival. Results: A total of 96 patients (median [range] age, 1.9 [0.4-18] years; 36 [38%] girls and 60 [63%] boys) were assessed, including 15 with very low risk, 28 with low risk, 23 with intermediate risk, and 30 with high risk, according to CHIC-HS criteria. There were a total of 13 cancer-related deaths; median (range) follow-up was 3.5 (0.1-17.8) years for those alive at the last follow-up. The estimated 5-year OS rates were 100% in the very low-risk group, 94.7% (95% CI, 68.1%-99.2%) in the low-risk group, 89.2% (95% CI, 63.1%-97.2%) in the intermediate-risk group, and 57.9% (95% CI, 34.6%-75.5%) in the high-risk group. In a multivariable analysis, we confirmed that CHIC-HS significantly estimated EFS (high-risk group vs very low- and low-risk groups: hazard ratio [HR], 45.59; 95% CI, 9.39-209.5; P < .001) and OS (high-risk group vs very low- and low-risk groups: HR, 21.95; 95% CI, 2.76-174.29; P < .001). In the subcohort of 84 patients for whom pretreatment tumor histological data were available, tumor epithelial histological subtypes were found to be significantly associated with both EFS and OS. Patients in the CHIC-HS high-risk group and with embryonal-only histological subtype had the highest risk of relapse or disease progression (high-risk: HR, 42.62; 95% CI, 9.91-203.9; embryonal: HR, 3.28; 95% CI, 1.21-8.9) and death (high-risk: HR, 18.78; 95% CI, 2.31-152.84; embryonal: HR, 7.12; 95% CI, 1.51-33.52). Conclusions and Relevance: This cohort study found that CHIC-HS performed as expected in an independent cohort that was more recently treated. Incorporation of pretreatment tumor histological data into CHIC-HS may provide additional prognostic value.

Tumor rupture in hepatoblastoma: A high risk factor?

BACKGROUND: Hepatoblastoma tumor rupture is a high-risk criterion in the SIOPEL 3/4 protocol. Little is known about the outcome of these children. METHODS: Radiological signs of possible tumor rupture, defined as peritoneal effusion, peritoneal nodules, or hepatic subcapsular hematoma, were reported in 24 of 150 patients treated for hepatoblastoma in France from January 2000 to December 2014 after central radiological expert review. RESULTS: Twenty-two patients with available clinical data were included (nine PRETEXT-I/II, six PRETEXT-III, seven PRETEXT-IV, and five had lung metastases). Five patients had a subcapsular hematoma only, and 17 patients had intraperitoneal rupture (subcapsular hematoma and peritoneal effusion). A hepatic biopsy was performed in 19 patients. Intraperitoneal rupture occurred before biopsy in 12 and after biopsy in three (including one with prebiopsy subcapsular hematoma) (missing data: two). All patients were treated with chemotherapy, with high-risk regimens including cisplatin or carboplatin and doxorubicin in 19 and cisplatin or carboplatin alone in three. Liver surgery was performed in 20 patients (including three liver transplants). Fifteen patients (68%) achieved complete remission. With a median follow-up of 5.5 years, 11 events occurred (six progressions and three relapses, including three peritoneal progressions/relapses, one surgical complication, and one second cancer) and eight patients died. One of eight patients with no other high-risk criterion had a relapse. The three-year event-free survival and overall survival rates were 49.6% (95% CI = 30-69) and 68.2% (40-84), respectively. CONCLUSIONS: Tumor rupture is predictive of poor prognosis with risk of peritoneal progression/relapse. However, it should not be a contraindication for liver transplantation.

Agenesis of the corpus callosum and hepatoblastoma.

Agenesis of the corpus callosum is a congenital brain malformation that can occur in isolation or as a component of a congenital syndrome. Hepatoblastoma (HB) is a rare tumor that comprises two thirds of primary hepatic neoplasms in children and adolescents. Up to 20% of children with HB have associated congenital anomalies. In addition to defined genetic syndromes such as Familial Adenomatous Polyposis, Beckwith-Wiedemann syndrome, Trisomy 13, and Trisomy 18, HB is significantly associated with kidney/bladder abnormalities. We present two children with multiple congenital anomalies, including agenesis of the corpus callosum, who were subsequently diagnosed with HB. Review of the literature revealed two patients with clinically-diagnosed Aicardi syndrome and HB. Due to the rarity of both agenesis of the corpus callosum and HB, this is likely a true association. Further investigation into the underlying genetic and molecular basis of this probable association is warranted.

Clinicopathological profile of hepatoblastoma: An experience from a tertiary care center in India.

BACKGROUND: Hepatoblastoma is the most common primary hepatic malignancy in the pediatric population. Advances in pathological evaluation, imaging, risk stratification, neo-adjuvant chemotherapy, and surgery including transplantation have improved survival of these children in the western countries. However, a successful outcome in developing countries such as India with limited resources poses great challenges to the clinician and the family. Histology plays a major role in determining the prognosis of these patients. METHODS: A retrospective study was done on 10 children diagnosed with hepatoblastoma between January 2010 and December 2015 in our institution. Clinical, laboratory, radiological, histopathological diagnoses, treatment, and outcome data were collected and analyzed. RESULTS: The median age of these children at diagnosis was 11 months, and only 1 child was premature at birth. Most children were presented with abdominal distension. One child had lung metastasis at presentation. Elevated alpha fetoprotein levels were present in 90% of the children. The histological types were fetal, embryonal, macrotrabecular, and mixed epithelial-mesenchymal types. SIOPEL risk stratification was done, which showed 40% of the children to be of high risk. Three children had PRETEXT 1, 2, and 4, respectively. CONCLUSION: Our study is significant with respect to the information on PRETEXT staging, risk status, and histological favorability. In developing countries with limited resources and low-socioeconomic status, it is important to have a multidisciplinary team approach and tailor treatment to manage these patients effectively and improve the overall survival.

Phenotype evolution and health issues of adults with Beckwith-Wiedemann syndrome.

BACKGROUND: Beckwith-Wiedemann syndrome (BWS) phenotype usually mitigates with age and data on adulthood are limited. Our study aims at reporting phenotype evolution and health issues in adulthood. METHODS: 34 patients (16 males), aged 18-58 years (mean 28.5) with BWS were enrolled. RESULTS: 26 patients were molecularly confirmed, 5 tested negative, and 3 were not tested. Final tall stature was present in 44%. Four patients developed Wilms' Tumor (2, 3, 5, and 10 years, respectively); one hepatoblastoma (22 years); one acute lymphoblastic leukemia (21 years); one adrenal adenoma and testicular Sertoli cell tumor (22 and 24 years, respectively); and three benign tumors (hepatic haemangioma, uterine myoma, and mammary fibroepithelioma). Surgery for BWS-related features was required in 85%. Despite surgical correction several patients presented morbidity and sequelae of BWS pediatric issues: pronunciation/swallow difficulties (n = 9) due to macroglossia, painful scoliosis (n = 4) consistent with lateralized overgrowth, recurrent urolithiasis (n = 4), azoospermia (n = 4) likely consequent to cryptorchidism, severe intellectual disability (n = 2) likely related to neonatal asphyxia and diabetes mellitus (n = 1) due to subtotal pancreatectomy for intractable hyperinsulinism. Four patients (two males) had healthy children (three physiologically conceived and one through assisted reproductive technology). CONCLUSIONS: Adult health conditions in BWS are mostly consequent to pediatric issues, underlying the preventive role of follow-up strategies in childhood. Malignancy rate observed in early adulthood in this small cohort matches that observed in the first decade of life, cumulatively raising tumor rate in BWS to 20% during the observation period. Further studies are warranted in this direction.

Hepatoblastoma Biology Using Isotope Ratio Mass Spectrometry: Utility of a Unique Technique for the Analysis of Oncological Specimens.

INTRODUCTION: Hepatoblastoma is the most common primary liver tumor in children. However, it occurs rarely, with an incidence of 0.5-1.5 cases per million children. There is no clear explanation of the relationship between clinicopathologic features, therapy, and outcome in hepatoblastoma cases, so far. One of the most widely accepted prognostic factors in hepatoblastoma is histology of the tumor. The aim of the study was to determine the potential differences in biology of hepatoblastoma histological subtypes at the atomic level using the unique method of isotope ratio mass spectrometry, which is especially valuable in examination of small groups of biological samples. MATERIAL/METHODS: Twenty-four measurements of nitrogen stable isotope ratio, carbon stable isotope ratio and total carbon to nitrogen mass ratio in fetal and embryonal hepatoblastoma tissue were performed using a Sercon 20-22 Continuous Flow Isotope Ratio Mass Spectrometer (CF-IRMS) coupled with a Sercon SL elemental analyzer for simultaneous carbon-nitrogen-sulfur (NCS) analysis. RESULTS: A difference of about 1.781‰ in stable nitrogen isotope 15N/14N ratio was found between examined hepatoblastoma histological subtypes. CONCLUSIONS: The prognosis in liver tumors cases in children may be challenging particularly because of the lack of versatile methods of its evaluation. Isotope ratio mass spectrometry allows one to determine the difference between hepatoblastoma histological subtypes and clearly indicates the cases with the best outcome.

Dynamic monitoring of the cytotoxic effects of protoberberine alkaloids from Rhizoma Coptidis on HepG2 cells using the xCELLigence system.

AIM: To investigate the cytotoxic effects of the six protoberberine alkaloids (PAs) from Rhizoma Coptidis on HepG2 cells. METHOD: A systematic screening was conducted to investigate the dynamic response of HepG2 cells to the PAs using the impedance-based xCELLigence system. Cisplatin was selected as the positive control. The real time, concentration-response curves and the 50% inhibitory concentrations (IC50) were acquired to evaluate the anticancer activity of the PAs. RESULTS: All of the six PAs inhibited cell growth and induce death in HepG2 cells in a time- and concentration-dependent manner. The IC50 values of cisplatin, berberine, columbamine, coptisine, epiberberine, jatrorrhizine, and palmatine were 5.13, 42.33, 226.54, 36.90, 302.72, 383.54, and 456.96 µg·mL(-1), respectively. The results obtained using the xCELLigence system corresponded well with those of the conventional methods. CONCLUSION: The xCELLigence system is a reliable and efficient tool for real-time screening of the cytotoxic effect of compounds in cell-based in vitro assays. Coptisine and berberine, with methylenedioxy group at C2 and C3 on the phenyl ring showed stronger effect.than the other four PAs. However, compared with cisplatin, the six PAs didn't show obvious cytotoxic effect on HepG2 cells. These results provided some useful data for the evaluation of the anticancer compounds, and the clinical application of traditional Chinese medicine.

Crosstalk between beta-catenin and snail in the induction of epithelial to mesenchymal transition in hepatocarcinoma: role of the ERK1/2 pathway.

Epithelial to mesenchymal transition (EMT) is an integral process in the progression of many epithelial tumors. It involves a coordinated series of events, leading to the loss of epithelial features and the acquisition of a mesenchymal phenotype, resulting in invasion and metastasis. The EMT of hepatocellular carcinoma (HCC) cells is thought to be a key event in intrahepatic dissemination and distal metastasis. In this study, we used 12-O-tet-radecanoylphorbol-13-acetate (TPA) to dissect the signaling pathways involved in the EMT of HepG2 hepatocarcinoma cells. The spectacular change in phenotype induced by TPA, leading to a pronounced spindle-shaped fibroblast-like cell morphology, required ERK1/2 activation. This ERK1/2-dependent EMT process was characterized by a loss of E-cadherin function, modification of the cytoskeleton, the acquisition of mesenchymal markers and profound changes to extracellular matrix composition and mobility. Snail was essential for E-cadherin repression, but was not sufficient for full commitment of the TPA-triggered EMT. We found that TPA triggered the formation of a complex between Snail and ß-catenin that activated the Wnt pathway. This study thus provides the first evidence for the existence of a complex network governed by the ERK1/2 signaling pathway, converging on the coregulation of Snail and the Wnt/ß-catenin pathway and responsible for the onset and the progression of EMT in hepatocellular carcinoma cells.

Detection of CD133 (prominin-1) in a human hepatoblastoma cell line (HuH-6 clone 5).

We examined CD133 distribution in a human hepatoblastoma cell line (HuH-6 clone 5). We directly observed the cultured cells on a pressure-resistant thin film (silicon nitride thin film) in a buffer solution by using the newly developed atmospheric scanning electron microscope (ASEM), which features an open sample dish with a silicon nitride thin film window at its base, through which the scanning electron microscope beam scans samples in solution, from below. The ASEM enabled observation of the ventral cell surface, which could not be observed using standard SEM. However, observation of the dorsal cell surface was difficult with the ASEM. Therefore, we developed a new method to observe the dorsal side of cells by using Aclar® plastic film. In this method, cells are cultured on Aclar plastic film and the dorsal side of cells is in contact with the thin silicon nitride film of the ASEM dish. A preliminary study using the ASEM showed that CD133 was mainly localized in membrane ruffles in the peripheral regions of the cell. Standard transmission electron microscopy and scanning electron microscopy revealed that CD133 was preferentially concentrated in a complex structure comprising filopodia and the leading edge of lamellipodia. We also observed co-localization of CD133 with F-actin. An antibody against CD133 decreased cell migration. Methyl-ß-cyclodextrin treatment decreased cell adhesion as well as lamellipodium and filopodium formation. A decrease in the cholesterol level may perturb CD133 membrane localization. The results suggest that CD133 membrane localization plays a role in tumor cell adhesion and migration.

Hepatoblastoma en el adulto / Adult hepatoblastoma

El hepatoblastoma (HB) en el adulto (HBA) es un tumor muy infrecuente del que se han descrito 45 casos hasta junio de 2012. A diferencia del HB en la infancia (HBI), tiene un pronóstico fatal. Presentamos el caso de una mujer de 37 años, asintomática, que consulta por una masa hepática de 12 cm de diámetro que ocupa los segmentos 5 y 6 del hígado, alfa-fetoproteína de 1.556,30 UI/ml. Se realizó bisegmentectomía. La histología confirmó el diagnóstico de HB con presencia de células epiteliales formando túbulos y estructuras trabecu - lares con marcadores para hepatocitos y colangiocitos. La enferma falleció a los 10 meses por progresión de la enfermedad. Recientemente se ha confirmado la mutación en la vía de señalización Wnt/β- Catenina en el HBI y su relación con un pronóstico peor. Debido a su mal pronóstico, parece lógico aplicar las pautas terapéuticas descritas en la población infantil, en la que se obtienen mejores resultados(AU)

Adult hepatoblastoma (AHB) is a very rare tumor, having been described 45 cases up to June 2012. In contrast to HB in infancy (IHB), it has poor prognosis. We present the case of a 37-year-old asymptomatic woman who consulted for a large –12 cm diameter– mass involving segments 5 and 6 of the liver, and alfa-fetoprotein of 1,556,30 UI/mL. A bisegmentectomy was carried out. The microscopic study confirmed the AHB diagnosis, revealing the presence of epithelial cells forming clusters, trabecular patterns and tubules. The patient died on the 10th postoperative month due to progression disease. The Wnt/β-Catenin signaling pathway mutation has been reported and associated with a poor prognosis in IHB. Due to the AHB poor prognosis, seems reasonable to introduce the therapeutic regimens described in children who have a better outcome(AU)

Hepatoblastoma evaluated by 18F-fluoromethyl choline PET/CT.

Hepatoblastoma is a rare carcinoma mostly seen in children. Neoadjuvant chemotherapy followed by resection and adjuvant chemotherapy is the optimal treatment. We present the case of an 18-year-old woman who presented with abdominal pain, nausea, bloating, and fatigue. MRI showed 3 hepatic lesions with high signal intensity on arterial phase T1-weighted images and slight washout on the late phase, suggestive for hepatocellular carcinoma. Laboratory examinations revealed plasma α-feto-protein of 114,245 µg/L. Subsequent baseline and posttreatment F-fluoromethyl choline PET/CT were performed to possibly evaluate extent of the disease and assess disease response after neoadjuvant chemotherapy.

The effects of garlic-derived sulfur compounds on cell proliferation, caspase 3 activity, thiol levels and anaerobic sulfur metabolism in human hepatoblastoma HepG2 cells.

The aim of the present studies was to determine whether the mechanism of biological action of garlic-derived sulfur compounds in human hepatoma (HepG2) cells can be dependent on the presence of labile sulfane sulfur in their molecules. We investigated the effect of allyl sulfides from garlic: monosulfide, disulfide and trisulfide on cell proliferation and viability, caspase 3 activity and hydrogen peroxide (H(2)O(2)) production in HepG2 cells. In parallel, we also examined the influence of the previously mentioned compounds on the levels of thiols, glutathione, cysteine and cysteinyl-glycine, and on the level of sulfane sulfur and the activity of its metabolic enzymes: rhodanese, 3-mercaptopyruvate sulfurtransferase and cystathionase. Among the compounds under study, diallyl trisulfide (DATS), a sulfane sulfur-containing compound, showed the highest biological activity in HepG2 cells. This compound increased the H(2)O(2) formation, lowered the thiol level and produced the strongest inhibition of cell proliferation and the greatest induction of caspase 3 activity in HepG2 cells. DATS did not affect the activity of sulfurtransferases and lowered sulfane sulfur level in HepG2 cells. It appears that sulfane sulfur containing DATS can be bioreduced in cancer cells to hydroperthiol that leads to H(2)O(2) generation, thereby influencing transmission of signals regulating cell proliferation and apoptosis.

MicroRNA-492 is processed from the keratin 19 gene and up-regulated in metastatic hepatoblastoma.

UNLABELLED: MicroRNAs (miRNAs) are well-known regulators of proliferation, apoptosis, and differentiation and are recognized to play an important role in the development of cancers. Here we aimed to identify the functional contribution of miRNAs to the biology of hepatoblastoma (HB), the most common malignant liver tumor in childhood. As overexpression of the oncogene PLAG1 (pleomorphic adenoma gene 1) is a characteristic phenomenon in HB, we used RNA interference and subsequent miRNA array analysis to identify miR-492 as most strongly influenced by PLAG1. We provide novel experimental evidence that miR-492 can originate from the coding sequence of the HB marker gene keratin 19 (KRT19). In agreement with these in vitro observations, significantly elevated levels of coexpressed KRT19 and miR-492 were particularly found in metastatic HB tumor samples. Stable overexpression of miR-492 in HB cell clones served to identify a broad range of differentially expressed transcripts, including several candidate targets of miR-492 predicted by computational algorithms. Among those the liver enzyme BAAT showed significant association with miR-492 expression in HB tumor samples. CONCLUSION: A close functional relationship between KRT19 and miR-492 was identified that may play an important role in the progression of malignant embryonal liver tumors. Additionally, miR-492 and its associated targets might serve as new HB biomarkers of clinical utility and could assist to explore targeted therapies, especially in metastatic HB with a poor prognosis.

Hepatoblastoma: experience from a single center.

BACKGROUND: The cornerstones of successful treatment of hepatoblastoma (HB) include preoperative chemotherapy followed by complete anatomical resection of tumor, followed by chemotherapy. Advances in chemotherapy in the last 2 decades have been associated with a higher rate of tumor response and possibly a greater potential for resectability. AIMS: We analyzed our single center experience with neoadjuvant chemotherapy (NACT) and surgery in HBs. SETTINGS AND DESIGN: Our study included all children with HBs who received NACT and underwent surgical excision from January 1997 to July 2004. MATERIALS AND METHODS: Patient characteristics, clinical features, clinical course, treatment modalities, and long-term outcome were analyzed. RESULTS: There were 9 boys and 3 girls, aged 5-60 months (median age at tumor diagnosis was 24 months). All received NACT containing cisplatin and doxorubicin. Of the 12 children, 9 underwent hepatectomy and among them, 4 patients each had right and left hepatectomy and 1 patient underwent right extended hepatectomy. After surgery, all patients completed rest of the chemotherapy course (total 6 cycles). R0 resection was carried out in all the 9 cases with no life-threatening complications. CONCLUSIONS: Our experience of the 9 cases, although less in number, reaffirms the advantages of NACT followed by surgery. The prognosis for patients with resectable tumors is fairly good in combination with chemotherapy.

Screening and cloning for proteins transactivated by the PS1TP5 protein of hepatitis B virus: a suppression subtractive hybridization study.

AIM: To clone and identify human genes transactivated by PS1TP5 by constructing a cDNA subtractive library with suppression subtractive hybridization (SSH) technique. METHODS: SSH and bioinformatics techniques were used for screening and cloning of the target genes transactivated by PS1TP5 protein. The mRNA was isolated from HepG2 cells transfected with pcDNA3.1(-)-myc-his(A)-PS1TP5 and pcDNA3.1(-)-myc-his(A) empty vector, respectively, and SSH technique was employed to analyze the differentially expressed DNA sequence between the two groups. After digestion with restriction enzyme Rsa I, small size cDNAs were obtained. Then tester cDNA was divided into two groups and ligated to the specific adaptor 1 and adaptor 2, respectively. The tester cDNA was hybridized with driver cDNA twice and subjected to nested PCR for two times, and then subcloned into T/A plasmid vectors to set up the subtractive library. Amplification of the library was carried out with E. coli strain DH5alpha. The cDNA was sequenced and analyzed in GenBank with Vector NTI 9.1 and NCBI BLAST software after PCR amplification. RESULTS: The subtractive library of genes transactivated by PS1TP5 was constructed successfully. The amplified library contained 90 positive clones. Colony PCR showed that 70 clones contained 200-1000-bp inserts. Sequence analysis was performed in 30 clones randomly, and the full-length sequences were obtained by bioinformatics technique. Altogether 24 coding sequences were obtained, which consisted of 23 known and 1 unknown. One novel gene with unknown functions was found and named as PS1TP5TP1 after being electronically spliced, and deposited in GenBank (accession number: DQ487761). CONCLUSION: PS1TP5 is closely correlated with immunoregulation, carbohydrate metabolism, signal transduction, formation mechanism of hepatic fibrosis, and occurrence and development of tumor. Understanding PS1TP5 transactive proteins may help to bring some new clues for further studying the biological functions of pre-S1 protein.

Signaling pathway of insulin-like growth factor-II as a target of molecular therapy for hepatoblastoma.

AIM: To address the possibility that insulin-like growth factor (IGF)-II is a growth factor and its signaling pathway so as to develop a molecular therapy for hepatoblastoma. METHODS: Huh-6 and HepG2, human hepatoblastoma cell lines, were used. IGF-II was added to the medium deprived of serum. Western blot analysis was performed to clarify the expression of IGF-I receptor (IGF-IR). Inhibitors of IGF-IR (piclopodophyllin, PPP), phosphatidyl-inositol (PI) 3-kinase (LY294002 and Wortmannin), or mitogen-activated protein (MAP) kinase (PD98059) were added to unveil the signaling pathway of IGF-II. Cells were analyzed morphologically with hematoxylin-eosin staining to reveal the mechanism of suppression of cell proliferation. RESULTS: IGF-II stimulated cells proliferated to 2.7 (269%+/-76%) (mean+/-SD) (Huh-6) and 2.1 (211%+/-85%) times (HepG2). IGF-IR was expressed in Huh-6 and HepG2. PPP suppressed the cell number to 44%+/-11% (Huh-6) and 39%+/-5% (HepG2). LY294002 and Wortmannin suppressed the cell number to 30%+/-5% (Huh-6), 44%+/-0.4% (HepG2), 49%+/-1.0% (Huh-6) and 46%+/-1.1% (HepG2), respectively. PD98059 suppressed the cell number to 33%+/-11% for HepG2 but not for Huh-6. When cell proliferation was prohibited, many Huh-6 and HepG2 cells were dead with pyknotic or fragmented nuclei, suggesting apoptosis. CONCLUSION: IGF-II was shown to be a growth factor of hepatoblastoma via IGF-I receptor and PI3 kinase which were good candidates for target of molecular therapy.

Atomic force microscopy-based cell nanostructure for ligand-conjugated quantum dot endocytosis.

While it has been well demonstrated that quantum dots (QDs) play an important role in biological labeling both in vitro and in vivo, there is no report describing the cellular nanostructure basis of receptor-mediated endocytosis. Here, nanostructure evolution responses to the endocytosis of transferrin (Tf)-conjugated QDs were characterized by atomic force microscopy (AFM). AFM-based nanostructure analysis demonstrated that the Tf-conjugated QDs were specifically and tightly bound to the cell receptors and the nanostructure evolution is highly correlated with the cell membrane receptor-mediated transduction. Consistently, confocal microscopic and flow cytometry results have demonstrated the specificity and dynamic property of Tf-QD binding and internalization. We found that the internalization of Tf-QD is linearly related to time. Moreover, while the nanoparticles on the cell membrane increased, the endocytosis was still very active, suggesting that QD nanoparticles did not interfere sterically with the binding and function of receptors. Therefore, ligand-conjugated QDs are potentially useful in biological labeling of cells at a nanometer scale.