Patterns of ALK expression in different human cancer types

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• Oncogenic anaplastic lymphoma kinase (ALK) gene fusions are implicated in certain cancers.
• ALK tyrosine kinase inhibitors, like crizotinib, show promise for ALK fusion-positive cancers.
• A thorough investigation of ALK fusions and expression in solid tumors is needed.

Purpose of the Study:

• To comprehensively analyze solid tumor types for anaplastic lymphoma kinase (ALK) gene fusions.
• To investigate ALK fusion-associated expression across diverse solid tumor entities.
• To determine the prevalence of ALK alterations in human solid cancers.

Main Methods:

• Real-time PCR screening of 1000 tumor samples across 29 entities to detect ALK alterations.
• Fluorescence in situ hybridization (FISH) analysis for ALK break-apart.
• Immunohistochemistry (IHC) analysis for ALK expression.

Main Results:

• Real-time PCR detected ALK expression in 29% of analyzed solid tumors.
• FISH analysis did not identify any ALK rearrangements in the screened samples.
• Immunohistochemistry (IHC) failed to detect ALK expression, indicating low-level, non-fusion-related expression.

Conclusions:

• Anaplastic lymphoma kinase (ALK) expression varies across cancer types, detectable by sensitive methods like real-time PCR.
• Low-level ALK expression is not indicative of oncogenic ALK fusions and is missed by less sensitive techniques like IHC.
• Oncogenic ALK fusion is an infrequent occurrence in human solid tumors.