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Betulinic acid: a new chemotherapeutic agent in the treatment of neuroectodermal tumors
S Fulda1, I Jeremias, T Pietsch
1University Children's Hospital, Ulm, Germany.
Abstract:
We identified betulinic acid (BetA) as a new cytotoxic agent active against neuroectodermal tumor cells including neuroblastoma, medulloblastoma, glioblastoma and Ewing's sarcoma cells representing the most common solid tumors of childhood. BetA induced apoptosis independent of wild-type p53 protein and accumulation of death-inducing ligand/receptor systems such as CD95. BetA had a direct effect on mitochondria resulting in the release of soluble apoptogenic factors such as cytochrome c or AIF from mitochondria into the cytosol where they induced activation of caspases. Overexpression of the anti-apoptotic proteins Bcl-2 or Bcl-XL that blocked loss of the mitochondrial membrane potential and cytochrome c release from mitochondria conferred resistance to BetA at the level of mitochondrial dysfunction, protease activation and nuclear fragmentation. Neuroblastoma cells resistant to CD95- or doxorubicin-triggered apoptosis remained sensitive to treatment with BetA suggesting that BetA may bypass some forms of resistance. Moreover, BetA exhibited potent antitumor activity on primary tumor cell cultures from all neuroblastoma (4/4), all medulloblastoma (4/4) and most glioblastoma patients (20/24) ex vivo. These findings suggest that BetA may be a promising new agent in the treatment of neuroectodermal tumors in vivo.
Insights
Betulinic acid (BetA) shows potent cytotoxic activity against childhood neuroectodermal tumors by inducing apoptosis through mitochondrial pathways. This agent may offer a promising new treatment option, bypassing some resistance mechanisms.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Neuroectodermal tumors, including neuroblastoma and glioblastoma, are leading causes of childhood cancer.
- Current treatments face challenges with resistance and toxicity.
- Novel therapeutic agents are urgently needed for these aggressive pediatric cancers.
Purpose of the Study:
- To identify and characterize new cytotoxic agents effective against pediatric neuroectodermal tumors.
- To investigate the mechanism of action of betulinic acid (BetA) in these cancer cells.
- To evaluate the ex vivo antitumor potential of BetA on patient-derived tumor cells.
Main Methods:
- Cell viability assays were performed on various neuroectodermal tumor cell lines treated with BetA.
- Apoptosis induction pathways were analyzed, including p53 independence, CD95 signaling, and mitochondrial-mediated apoptosis.
- Mitochondrial membrane potential, cytochrome c release, and caspase activation were assessed.
- Ex vivo drug sensitivity assays were conducted on primary tumor cell cultures from neuroblastoma, medulloblastoma, and glioblastoma patients.
Main Results:
- Betulinic acid (BetA) demonstrated significant cytotoxicity against neuroblastoma, medulloblastoma, glioblastoma, and Ewing's sarcoma cells.
- BetA induced apoptosis independently of p53 and CD95 signaling, primarily through direct mitochondrial damage.
- Mitochondrial dysfunction, characterized by cytochrome c and AIF release, was a key event in BetA-induced cell death.
- Overexpression of Bcl-2 or Bcl-XL conferred resistance to BetA by inhibiting mitochondrial dysfunction.
- BetA effectively bypassed resistance mechanisms observed with CD95 or doxorubicin treatments.
- Ex vivo studies showed potent antitumor activity of BetA against primary cultures of neuroblastoma, medulloblastoma, and glioblastoma.
Conclusions:
- Betulinic acid (BetA) is a novel cytotoxic agent with significant potential for treating pediatric neuroectodermal tumors.
- BetA's mechanism involves direct mitochondrial apoptosis induction, offering an alternative pathway that may overcome existing drug resistance.
- Further in vivo studies are warranted to explore BetA's therapeutic efficacy in neuroectodermal tumor treatment.
