Identification of compounds overcoming differentiation blocks in solid tumors utilizing a novel cell-based screening system

Purpose:

Targeting tumor specific differentiation blocks by activating cellular differentiation programs is a promising strategy for tumor treatment. Differentiating agents are supposed to potently reduce solid cancer cell tumorigenicity and to render cells more prone to common therapies. However, the pathophysiological mechanisms leading to maturation arrest in solid tumors are only poorly understood hampering development of targeted drugs.

Materials and methods:

We developed a cell-based phenotypic high-throughput screening system which allows the identification of potential differentiation inducing agents via the quantification of two innovative differentiation markers. MDA-MB-231 and A549 cells were used as in vitro models for early and late differentiation arrest, respectively. Differentiation-inducing potency of the identified substances was validated by quantifying the expression of characterized differentiation markers by qRT-PCR analysis. Additionally, changes of differentiation marker levels were investigated by immunofluorescence microscopy.

Results:

Testing a databank of over one-thousand pharmacologically active compounds identified ten substances as possible hit-candidates. Validation experiments confirmed two hit-to-lead candidates with a high differentiation-inducing potential in each tumor model. All candidates showed no significant toxic effect in a preclinical toxicity test in primary human hepatocytes.

Summary:

We have successfully revealed a so far undescribed differentiating effect for two different substance classes in MDA-MB-231 and A549 cancer cell lines. Further studies will be performed to investigate the compounds' molecular mechanisms of action and their potential suitability for anti-tumor drug development.