Markedly divergent effects of Ouabain on a Temozolomide-resistant (T98G) vs. a Temozolomide-sensitive (LN229) Glioblastoma cell line.

Background: Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor with poor prognosis. GMB are highly recurrent mainly because of radio- and chemoresistance. Radiotherapy with Temozolomide (TMZ) is until today the golden standard adjuvant therapy, however, the optimal treatment of recurrent glioblastoma remains controversial.

"The Lower Threshold" phenomenon in tumor cells toward endogenous digitalis-like compounds: Responsible for tumorigenesis?

Since their first discovery as potential anti-cancer drugs decades ago, there is increasing evidence that digitalis-like compounds (DLC) have anti-tumor effects. Less is known about endogenous DLC (EDLC) metabolism and regulation. As stress hormones synthesized in and secreted from the adrenal gland, they likely take part in the hypothalamo-pituitary-adrenal (HPA) axis.

Na/K-ATPase, endogenous digitalis like compounds and cancer development -- a hypothesis.

The primary transport system of sodium and potassium across the plasma cell membrane, the Na/K-ATPase, is a vital enzyme involved in numerous cellular events. This enzyme is the receptor for plant and amphibian steroids such as ouabain, digoxin and bufalin. In the past decade several endogenous steroids, identical or similar to the plant and amphibian steroids, termed here collectively digitalis-like compounds (DLC), have been identified in human tissues.