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Updated: Jun 28, 2026
High-throughput Screening for Chemical Modulators of Post-transcriptionally Regulated Genes
Published on: March 3, 2015
High throughput screening of a small molecule one-bead-one-compound combinatorial library to identify attenuators of
See-Hyoung Park1, Xiaobing Wang, Ruiwu Liu
1Division of Nephrology, University of California, Davis, California 95616, USA.
Abstract:
Kidney cancer is notoriously difficult to treat when metastatic due to its resistance to conventional chemotherapy. p21 is a cyclin kinase inhibitor which, in many tumor cell lines, conveys an antiapoptotic function through its induction by the DNA damage responsive p53 pathway, such that attenuation of p21 sensitizes several disparate cancer cell lines to DNA-damaging chemotherapy. Since clinical applications with therapeutic antisense and siRNA approaches are problematic, we sought to discover other methods to inhibit p21 which are more readily translatable to the clinic. Utilizing an on-bead enzyme-linked colorimetric binding assay, we screened a diverse one-bead-one-compound combinatorial small molecule library and identified 12 candidate compounds which bind p21. Each of the 12 candidate compounds was synthesized and tested individually and three ligands were found which had the highest p21 binding affinity and yielded similar chemical structure. These three compounds caused dose-dependent cytotoxicity as well as apoptosis when exposed to two RCC cell lines. In addition, these compounds sensitized cells to apoptosis when incubated with doxorubicin such that a lower dose of doxorubicin was required in the presence of the compounds for equivalent cell killing. Interestingly, a representative of the three compounds decreased p21 levels by specific induction of ubiquitin-dependent proteosome degradation. Thus, by high throughput screening of thousands of candidate small molecules, we have identified compounds which attenuate p21, cause RCC cell apoptosis and sensitize RCC cells to DNA-damaging chemotherapy. These compounds are currently being evaluated in in vivo assays as potential novel therapeutic for RCC.
Insights
Researchers identified novel small molecules that inhibit p21, a protein promoting cancer cell survival. These compounds induce kidney cancer cell death and enhance chemotherapy effectiveness, offering a promising new therapeutic avenue for metastatic renal cell carcinoma (RCC).
Area of Science:
- Oncology
- Molecular Biology
- Drug Discovery
Background:
- Metastatic kidney cancer (RCC) exhibits resistance to conventional chemotherapy.
- The protein p21, induced by the p53 pathway, promotes cancer cell survival and anti-apoptosis.
- Current antisense and siRNA strategies for p21 inhibition face clinical translation challenges.
Purpose of the Study:
- To identify novel small molecules that inhibit p21 for potential RCC therapy.
- To find alternative methods to attenuate p21 beyond antisense and siRNA approaches.
- To develop new treatments for drug-resistant metastatic kidney cancer.
Main Methods:
- A high-throughput screening of a combinatorial small molecule library using an on-bead enzyme-linked colorimetric binding assay.
- Identification and synthesis of 12 candidate compounds that bind to p21.
- In vitro testing of candidate compounds for cytotoxicity, apoptosis induction, and chemosensitization in RCC cell lines.
Main Results:
- Three small molecules demonstrated high binding affinity for p21.
- These compounds induced dose-dependent cytotoxicity and apoptosis in two RCC cell lines.
- The identified compounds sensitized RCC cells to doxorubicin, reducing the required chemotherapeutic dose.
- One compound was shown to decrease p21 levels via ubiquitin-dependent proteasome degradation.
Conclusions:
- Novel small molecules targeting p21 have been identified through high-throughput screening.
- These compounds effectively induce apoptosis and sensitize renal cell carcinoma cells to chemotherapy.
- The identified p21 inhibitors represent potential novel therapeutics for metastatic kidney cancer, currently undergoing in vivo evaluation.
