Ultrastructure and nuclear architecture of telomeric chromatin revealed by correlative light and electron microscopy.

Telomeres, the ends of linear chromosomes, are composed of repetitive DNA sequences, histones and a protein complex called shelterin. How DNA is packaged at telomeres is an outstanding question in the field with significant implications for human health and disease. Here, we studied the architecture of telomeres and their spatial association with other chromatin domains in different cell types using correlative light and electron microscopy. To this end, the shelterin protein TRF1 or TRF2 was fused in tandem to eGFP and the peroxidase APEX2, which provided a selective and electron-dense label to interrogate telomere organization by transmission electron microscopy, electron tomography and scanning electron microscopy. Together, our work reveals, for the first time, ultrastructural insight into telomere architecture. We show that telomeres are composed of a dense and highly compacted mesh of chromatin fibres. In addition, we identify marked differences in telomere size, shape and chromatin compaction between cancer and non-cancer cells and show that telomeres are in direct contact with other heterochromatin regions. Our work resolves the internal architecture of telomeres with unprecedented resolution and advances our understanding of how telomeres are organized in situ.

Diagnostic value of serum human epididymis protein 4 in esophageal squamous cell carcinoma.

BACKGROUND: Numerous studies have demonstrated that human epididymis protein 4 (HE4) is overexpressed in various malignant tissues including ovarian, endometrial, lung, breast, pancreatic, and gastric cancers. However, no study has examined the diagnostic impact of HE4 in patient with esophageal squamous cell carcinoma (ESCC) until now. AIM: To analyze the value of four serum tumor markers for the diagnosis of ESCC, and examine the associations of serum levels of HE4 with ESCC patients' clinicopathological characteristics. METHODS: The case group consisted of 80 ESCC patients, which were compared to a control group of 56 patients with benign esophageal disease. Serum levels of HE4, carcinoma embryonic antigen (CEA), alpha fetal protein, and carbohydrate antigen 19-9 (CA19-9) were detected by ELISA. The associations of serum HE4 levels with ESCC patients' clinicopathological characteristics such as gender, tumor location, and pathological stage were also examined after operation. RESULTS: The result of ELISA showed that serum HE4 level was significantly higher in the patients with ESCC than in the controls, and the staining intensity was inversely correlated with the pathological T and N stages. Serum HE4 levels had a sensitivity of 66.2% and specificity of 78.6% when the cutoff value was set at 3.9 ng/mL. Moreover, the combined HE4 and CA19-9 increased the sensitivity to 83.33%, and interestingly, the combination of HE4 with CEA led to the most powerful sensitivity of 87.5%. Furthermore, A positive correlation was observed between HE4 serum levels and pathological T and N stages (P = 0.0002 and 0.0017, respectively), but there was no correlation between HE4 serum levels and ESCC patient gender (P = 0.4395) or tumor location (P = 0.6777). CONCLUSION: The results of this study suggest that detection of serum HE4 levels may be useful in auxiliary diagnosis and evaluation of the progression of ESCC.

Porphyrin-phospholipid liposomes permeabilized by near-infrared light.

The delivery of therapeutic compounds to target tissues is a central challenge in treating disease. Externally controlled drug release systems hold potential to selectively enhance localized delivery. Here we describe liposomes doped with porphyrin-phospholipid that are permeabilized directly by near-infrared light. Molecular dynamics simulations identified a novel light-absorbing monomer esterified from clinically approved components predicted and experimentally demonstrated to give rise to a more stable porphyrin bilayer. Light-induced membrane permeabilization is enabled with liposomal inclusion of 10 molar % porphyrin-phospholipid and occurs in the absence of bulk or nanoscale heating. Liposomes reseal following laser exposure and permeability is modulated by varying porphyrin-phospholipid doping, irradiation intensity or irradiation duration. Porphyrin-phospholipid liposomes demonstrate spatial control of release of entrapped gentamicin and temporal control of release of entrapped fluorophores following intratumoral injection. Following systemic administration, laser irradiation enhances deposition of actively loaded doxorubicin in mouse xenografts, enabling an effective single-treatment antitumour therapy.