Our activity runs in parallel in a number of direction to reach as securely and with the highest probability as possible our ultimate goal/objective: To facilitate the tumor-suppressive microRNAs hormonal properties in vivo in animal models with newly identified small compounds. This activity is layered through the following activities/aims:
1. Identify and assess the activity of compounds that are increasing expression and secretion of the tumor suppressive miR-34a (microRNA – 34a). MiR-34a is known as a tumor suppressive microRNA. Our program in this ERC project is to increase its expression, induce its secretion from cells, preferentially not from tumor cells to have an anti-tumor effect against the surrounding cancer cells. Whether these are primary tumors developing or metastasis. By performing a high throughput screen, we have identified a number of compounds that increase expression as well as secretion. These are CDK5 inhibitors. Two of those are already in the clinic. Now we are conducting in vivo experiments to validate the anti-cancer effect of increasing miR-34a.
2. Identify and assess the activity of compounds increasing expression and secretion of miR-122. We had reported before in our past papers (Gastroenterology 2016;151:999–1010; Gastroenterology 2017;153:1404–1415), that miR-122 is regulated by specific transcription factors. One specific compound, RS2982, that activates ROR, was found to be most effective. The anti-HCC activity of miR-122 is further investigated, to identify targets and mechanisms, see other sections of this report. To further validate these results, we have generated a miR-122 KO mice. Surprisingly we found that in this mouse, liver metastasis is progressing rapidly compared to wt mice. We have investigated this and found that this effects is dependent on ADAM17, a known target of miR-122. Upon knocking out miR-122 ADAM17 increase (as well as ADAM10, which has a similar effect). Furthermore, in a 2nd compound development screen we found additional 4 compounds with an even “better” effect of increasing expression and secretion of miR-122. The most effective compound is now investigated in vivo for anti-tumor effects. Surprisingly, we found that one of the compounds increases the hepatokine FGF21 levels. This finding could make it an anti-pancreatitis compound. Today, there is no available specific treatment for pancreatitis.
3. Determine the tumor suppressive mechanism of miR- 122. In this aim we have moved in a few directions:3a. Establish miR-122 knockout mice. 3b. CD24 is a cancer stem cell marker, also for primary liver cancers. CD24 signaling induces cancer cells proliferation. Our bioinformatic analysis revealed CD24 as a putative target gene of the well-known liver specific miR-122. It has been shown that the levels of miR-122 are drastically reduced in HCC. Since miR-122, a liver-specific tumor suppressor microRNA, and, CD24 have reciprocal expression in livers, we suggested that miR-122 could be a regulator of CD24.
4. Identify in a bias and an unbiased approaches microRNAs which regulate retrotransposition, a tumor initiating and progression events, and screening for microRNAs regulating HCC cell proliferation. We have identify miR-222 that suppress retrotransposition. Now we are investigating what regulates this miR-222. We find that the effect of miR-222 is through miR-222 host gene non-coding RNA.
