RITA downregulates Hedgehog-GLI in medulloblastoma and rhabdomyosarcoma via JNK-dependent but p53-independent...

Area of Science:

• Oncology
• Molecular Biology
• Cancer Signaling Pathways

Background:

• Aberrant Hedgehog (HH) signaling is a key driver in numerous cancers, including medulloblastoma and rhabdomyosarcoma.
• Targeting HH signaling is a promising therapeutic strategy for these malignancies.

Purpose of the Study:

• To investigate the effect of RITA, a p53 activator, on HH signaling in cancer cells.
• To evaluate the combined efficacy of RITA and the GLI antagonist GANT61 in preclinical cancer models.

Main Methods:

• Treatment of human medulloblastoma and rhabdomyosarcoma cell lines with RITA and/or GANT61.
• Assessment of HH signaling pathway components and downstream targets.
• Evaluation of cell proliferation, apoptosis, and tumor growth in xenograft models.
• RNA sequencing (RNA-seq) to analyze global gene expression changes.

Main Results:

• RITA downregulated HH signaling in cancer cells irrespective of p53 status, via ROS-independent JNK activation.
• In vitro, RITA sensitized cells to GANT61, enhancing apoptosis and reducing proliferation.
• In vivo, RITA and GANT61 suppressed tumor growth, but co-administration did not yield additive benefits.
• Combined treatment paradoxically reduced RITA's effect on HH target gene expression, despite broader pathway modulation and tumor reduction.

Conclusions:

• RITA effectively inhibits HH signaling in relevant cancer cells through a p53-independent mechanism.
• Combination therapy with RITA and GANT61 demonstrates complex interactions, with potential benefits beyond direct HH pathway inhibition.
• Further research is warranted to elucidate the mechanisms underlying the observed synergistic effects and to optimize combination strategies for cancer treatment.