Correlation between RICTOR overexpression and amplification in advanced solid tumors.

Area of Science:

• Oncology
• Molecular Biology
• Genomics

Background:

• Rapamycin-insensitive companion of mTOR (RICTOR) is crucial for cell proliferation and survival.
• RICTOR amplification is a potential therapeutic target in advanced solid cancers.
• Accurate diagnostic methods for RICTOR amplification beyond next-generation sequencing are needed.

Purpose of the Study:

• To evaluate immunohistochemistry (IHC) as a diagnostic tool for detecting RICTOR amplification in solid tumors.
• To assess the prevalence and heterogeneity of RICTOR overexpression in a large cohort of solid tumors.
• To correlate IHC findings with fluorescence in situ hybridization (FISH) results for RICTOR amplification.

Main Methods:

• Immunohistochemistry (IHC) was performed on 435 solid tumor tissues.
• Fluorescence in situ hybridization (FISH) was used to confirm RICTOR amplification in selected IHC-positive and negative cases.
• Statistical analysis was used to compare IHC and FISH results and assess correlations.

Main Results:

• RICTOR overexpression was detected in 49.0% of the 435 solid tumors analyzed.
• Heterogeneous RICTOR overexpression was observed in 32.4% of IHC-positive cases.
• FISH confirmed RICTOR amplification in 75.7% of RICTOR-overexpressed cases and 7.7% of IHC-negative cases, showing good correlation with IHC (r=0.60).

Conclusions:

• Heterogeneous RICTOR overexpression is common in various solid tumors.
• IHC is a reliable screening tool for identifying RICTOR amplification, especially in cases with heterogeneous expression.
• RICTOR IHC can guide further diagnostic testing for RICTOR amplification in advanced solid cancers.