A Three-Dimensional Culture-Drug Sensitivity Test Predicts MDM2 Inhibitor-Sensitivity in SMARCB1/INI1-Deficient...

Area of Science:

• Oncology
• Cancer Biology
• Genetics

Background:

• Loss of SMARCB1/INI1 expression is a hallmark of aggressive pediatric tumors like malignant rhabdoid tumors.
• SMARCB1/INI1 deficiency causes widespread transcriptional changes, complicating targeted therapy development.
• Identifying effective treatments for these rare and aggressive cancers remains a significant challenge.

Purpose of the Study:

• To investigate the feasibility of personalized drug selection for SMARCB1/INI1-deficient tumors using in vitro drug sensitivity profiling.
• To evaluate the utility of a short-term collagen gel-embedded three-dimensional culture-drug sensitivity test (3D-DST) for this purpose.

Main Methods:

• Utilized cell line-derived mouse xenograft (CDX) models of SMARCB1/INI1-deficient tumors.
• Performed a short-term collagen gel-embedded 3D culture-drug sensitivity test (3D-DST) to assess drug responses.
• Analyzed gene expression and protein levels (TP53, p21) in response to drug treatment.

Main Results:

• The 3D-DST successfully identified potential molecular targeting drugs, including inhibitors of aurora B kinase, mTOR, MAPK, WNT/β-catenin, and MDM2.
• A CDX tumor resistant to MDM2 inhibitors showed lower TP53 expression compared to a sensitive tumor.
• MDM2 inhibitor treatment altered gene expression and induced p21 in sensitive cells, but not in resistant cells.

Conclusions:

• The 3D-DST is a valuable tool for predicting drug sensitivity in SMARCB1/INI1-deficient tumors.
• This in vitro method can guide the personalized selection of targeted therapies for these challenging cancers.
• The findings support the development of tailored treatment strategies based on individual tumor drug profiling.