Cooperation of neurotrophin receptor TrkB and Her2 in breast cancer cells facilitates brain metastases

Gastric cancer with brain metastasis and the role of human epidermal growth factor 2 status

Central nervous system (CNS) metastases from cancers of the gastrointestinal tract (GIT) are rare, and occur in 0.16-0.69% of patients with gastric or gastro-esophageal (GE) junction cancer. Overexpression of the human epidermal growth factor 2 (HER-2) is associated with poor prognosis in the absence of HER-2-targeted therapy, and with an increased incidence of CNS metastases in patients with breast cancer. The role of HER-2 overexpression in CNS metastases is not well known in gastric adenocarcinoma. The purpose of the present retrospective study was to assess the incidence of CNS metastases and to evaluate the associations between the CNS and HER-2 status in a series of consecutive patients with gastric or GE junction cancer. Between 2007 and 2013, 300 patients with gastric cancer (GC) or gastroesophageal junction, were admitted to Piacenza General Hospital, Italy. These cases were retrospectively analyzed to evaluate CNS metastases. The metastases were diagnosed with imaging techniques performed on symptomatic patients. Gastric histological samples of patients with CNS metastases were reviewed and tested for HER-2. A total of 7 of the 300 patients (2.33%) with GC were observed to have CNS metastases and 6 (85.71%) had HER-2 positive disease. These patients exhibited a poor prognosis with a median overall survival rate of 4.1 months (range, 2.1-6.6 months). These results suggested there may be CNS recurrence susceptibility in patients with HER-2 positive GC. To the best of our knowledge, this is the first report that associates CNS metastases and HER-2 status in gastric or GE junction cancer.

Reactive Astrocytes in Brain Metastasis

Brain metastasis, the secondary growth of malignant cells within the central nervous system (CNS), exceeds the incidence of primary brain tumors (i.e., gliomas) by tenfold and are seemingly on the rise owing to the emergence of novel targeted therapies that are more effective in controlling extracranial disease relatively to intracranial lesions. Despite the fact that metastasis to the brain poses a unmet clinical problem, with afflicted patients carrying significant morbidity and a fatal prognosis, our knowledge as to how metastatic cells manage to adapt to the tissue environment of the CNS remains limited. Answering this question could pave the way for novel and more specific therapeutic modalities in brain metastasis by targeting the specific makeup of the brain metastatic niche. In regard to this, astrocytes have emerged as the major host cell type that cancer cells encounter and interact with during brain metastasis formation. Similarly to other CNS disorders, astrocytes become reactive and respond to the presence of cancer cells by changing their phenotype and significantly influencing the outcome of disseminated cancer cells within the CNS. Here, we summarize the current knowledge on the contribution of reactive astrocytes in brain metastasis by focusing on the signaling pathways and types of interactions that play a crucial part in the communication with cancer cells and how these could be translated into innovative therapies.