Identification of AHCY inhibitors using novel high-throughput mass spectrometry

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SAH quantification to assess AHCY enzyme inhibition

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Colon cancer develops when abnormal cells inside the colon begin to grow uncontrollably. Symptoms are not always present at the outset, but people might observe a change in their bowel habits or see dark or bright red blood in their stool as the disease progresses. According to the National Cancer Institute, colon cancer represents the third most common cancer in the United States, with about 100,000 new cases diagnosed each year. It is also the third leading cause of cancer-related deaths among both men and women in the United States. The discovery of new and more effective treatments continue to be discovered. Let’s take a closer look at one of the most promising targets at this time.
S-adenosylhomocysteine hydrolase (AHCY) hydrolyzes S-adenosylhomocysteine (SAH) to adenosine and L-homocysteine. In this article, Noriko Uchiyama first set up a Rapid HTS mass spectrophotometry screen to select the most potent compounds. From a library of 500,000 compounds, 310 primary hits were then further characterized and selected in a secondary cell-based assay using SAH quantification. As a well-known cell line used in a variety of studies to mimic colon cancer proliferation and response to inhibitors, HCT116 cells were used, helping to further confirm the most potent hits prior to SAR.
AHCY was found to be a key enzyme in other cellular cancer models including human T-cell lymphoma H9, LNCaP, and DU145 human prostate cancer cell lines.
One relevant target in cancer: AHCY enzyme. One reliable assay for drug screening: SAH quantification. Numerous possibilities for discovering a new generation of inhibitors to cure many types of cancers.
Now, you have everything you need to set up assays for your oncology programs.


S-adenosylhomocysteine hydrolase (AHCY) catalyzes the reversible hydrolysis of S-adenosylhomocysteine (SAH) to adenosine and l-homocysteine. This enzyme is frequently overexpressed in many tumor types and is considered to be a validated anti-tumor target. In order to enable the development of small molecule AHCY inhibitors as targeted cancer therapeutics we developed an assay based on a RapidFire high-throughput mass spectrometry detection system, which allows the direct measurement of AHCY enzymatic activity. This technique avoids many of the problems associate with the previously reported method of using a thiol-reactive fluorescence probes to measure AHCY activity. Screening of a ∼500,000 compound library using this technique identified multiple SAH competitive hits. Co-crystal structures of the hit compounds complexed with AHCY were obtained showing that the compounds indeed bind in the SAH site of the enzyme. In addition, some hit compounds increased the SAH levels in HCT116 cells and showed growth inhibition. These compounds could be promising starting points for the optimization of cancer treatments.


Biochemical Biophysical Research Communication. 2017 Sep 9;491(1):1-7.

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