Astrocytic brain tumours, including glioblastomas, are incurable neoplasms characterized by diffusely infiltrative growth. Here we show that many tumour cells in astrocytomas extend ultra-long membrane protrusions, and use these distinct tumour microtubes as routes for brain invasion, proliferation, and to interconnect over long distances. The resulting network allows multicellular communication through microtube-associated gap junctions. When damage to the network occurred, tumour microtubes were used for repair. Moreover, the microtube-connected astrocytoma cells, but not those remaining unconnected throughout tumour progression, were protected from cell death inflicted by radiotherapy. The neuronal growth-associated protein 43 was important for microtube formation and function, and drove microtube-dependent tumour cell invasion, proliferation, interconnection, and radioresistance. Oligodendroglial brain tumours were deficient in this mechanism. In summary, astrocytomas can develop functional multicellular network structures. Disconnection of astrocytoma cells by targeting their tumour microtubes emerges as a new principle to reduce the treatment resistance of this disease.

TMs can contribute to the resistance against standard treatment modalities in gliomas. Specific inhibition of TMs is a promising approach to reduce local recurrence after surgery and lower resistance to chemotherapy.

Early and progressive colonization of the healthy brain is one hallmark of diffuse gliomas, including glioblastomas. We recently discovered ultralong (Ͼ10 to hundreds of microns) membrane protrusions [tumor microtubes (TMs)] extended by glioma cells. TMs have been associated with the capacity of glioma cells to effectively invade the brain and proliferate. Moreover, TMs are also used by some tumor cells to interconnect to one large, resistant multicellular network. Here, we performed a correlative gene-expression microarray and in vivo imaging analysis, and identified novel molecular candidates for TM formation and function. Interestingly, these genes were previously linked to normal CNS development. One of the genes scoring highest in tests related to the outgrowth of TMs was tweety-homolog 1 (TTYH1), which was highly expressed in a fraction of TMs in mice and patients. Ttyh1 was confirmed to be a potent regulator of normal TM morphology and of TM-mediated tumor-cell invasion and proliferation. Glioma cells with one or two TMs were mainly responsible for effective brain colonization, and Ttyh1 downregulation particularly affected this cellular subtype, resulting in reduced tumor progression and prolonged survival of mice. The remaining Ttyh1-deficient tumor cells, however, had more interconnecting TMs, which were associated with increased radioresistance in those small tumors. These findings imply a cellular and molecular heterogeneity in gliomas regarding formation and function of distinct TM subtypes, with multiple parallels to neuronal development, and suggest that Ttyh1 might be a promising target to specifically reduce TM-associated brain colonization by glioma cells in patients.

No abstract

Both the perivascular niche (PVN) and the integration into multicellular networks by tumor microtubes (TMs) have been associated with progression and resistance to therapies in glioblastoma, but their specific contribution remained unknown. By long-term tracking of tumor cell fate and dynamics in the live mouse brain, differential therapeutic responses in both niches are determined. Both the PVN, a preferential location of long-term quiescent glioma cells, and network integration facilitate resistance against cytotoxic effects of radiotherapy and chemotherapy—independently of each other, but with additive effects. Perivascular glioblastoma cells are particularly able to actively repair damage to tumor regions. Population of the PVN and resistance in it depend on proficient NOTCH1 expression. In turn, NOTCH1 downregulation induces resistant multicellular networks by TM extension. Our findings identify NOTCH1 as a central switch between the PVN and network niche in glioma, and demonstrate robust cross-compensation when only one niche is targeted.

BackgroundDiffuse astrocytomas, including glioblastomas, are malignant brain tumors with notorious resistance to standard therapies. One hallmark of malignant gliomas is their highly infiltrative growth. To allow long‐range communication, exchange of molecules, and cell‐cell contact between these scattered tumor cells, mechanisms other than paracrine signaling seem requisite.Recent findingsWe recently described long and thin membrane tubes (tumor microtubes, or TMs) that interconnect single glioma cells to a functional network. The integration of cells into these networks protected them from the cytotoxic effects of radiotherapy and chemotherapy. There is growing interest in cell protrusions, membrane tubes, and cell‐cell connections today, not only in cancer research. For the first time, so‐called tunneling nanotubes (TNTs) were described as thin intercellular membrane tubes in 2004. Until now, such membrane tube connections have not only been described in diffuse astrocytomas, but also in other tumor entities and other diseases.ConclusionHere, we want to review the biological functions of TMs, their similarities and differences to TNTs and other cellular protrusions, as well as potential clinical applications.

No abstract

Abstract. Endocrine disruptors (EDs) with androgenic and anti-androgenic effects may alter reproductive function by binding to androgenic receptors (AR) and inducing or modulating AR-dependent responses in the male reproductive system. However, the molecular mechanism(s) underlying these events remains unclear. In the present study, pregnant Sprague Dawley (SD) rats were treated with testosterone propionate (TP), flutamide (Flu) and di-(2-ethylhexyl) phthalate (DEHP) from gestation days (GD) 11 to 21. Interestingly, maternal exposure to Flu or DEHP caused fluctuations in the neonatal levels of serum testosterone (T) and luteinizing hormone (LH). Serum testosterone and LH were upregulated by Flu, but these hormones were down-regulated by DEHP. The anogenital distances (AGD) of male newborns were determined at post-neonatal days (PND) 1, 21 and 63. Male rats treated prenatally with DEHP (100 mg/kg mother's body weight) or Flu showed an AGD shorter than that of control rats. At PND 63, sperm concentration, viability and motility were reduced in the maternal DEHP and Flu-treated groups. The numbers of seminiferous tubules were reduced in the Flu and DEHP-treated offspring when compared with the vehicle-and TPtreated groups, and the tubules of the testes at PND 63 were disrupted by a high dose of Flu. In addition, we found differential gene expression patterns by microarray analysis following ED exposure, particularly in sex determinationrelated genes. Although Flu and DEHP are considered to be identical with regard to their anti-androgenic effects, their effects on developing male reproductive organs were distinct, suggesting that Flu competes with endogenous T, while DEHP influences a different step in androgenesis. Key words: Flutamide, Male reproduction, Phthalate (J. Reprod. Dev. 55: [400][401][402][403][404][405][406][407][408][409][410][411] 2009) ecently, environmental, anti-androgenic compounds have been recognized as endocrine disruptors (EDs) because of their hormone-like activities. Anti-androgenic chemicals have the potential to interfere with male reproductive development and function in humans and animals. The EDs are thought to act via many mechanisms, such as by decreasing androgen synthesis, exerting effects on the pituitary-gonadal axis and/or blocking the androgen receptor (AR) [1,2]. The consequences of these actions may cause abnormal hormonal regulation and gene expression.It has been demonstrated that the AR plays a critical role in control of male sexual differentiation. During mammalian sex differentiation, the androgens, testosterone (T) and its metabolite dihydrotestosterone (DHT), produced by the fetal/neonatal male during sexual differentiation are critical factors in the male phenotype [3]. Sex development continues postnatally with the onset of secondary sexual characteristics at puberty and the acquisition of reproductive capacity. In addition, the differentiation of the Wolffian structures (e.g., the epididymis, vas deferens and seminal vesicles) appears to be T-mediated, while ma...