Hutchinson-Gilford progeria syndrome (HGPS) is a rare autosomal dominant genetic disease that is caused by a silent mutation of the LMNA gene encoding lamins A and C (lamin A/C). The G608G mutation generates a more accessible splicing donor site than does WT and produces an alternatively spliced product of LMNA called progerin, which is also expressed in normal aged cells. In this study, we determined that progerin binds directly to lamin A/C and induces profound nuclear aberrations. Given this observation, we performed a random screening of a chemical library and identified 3 compounds (JH1, JH4, and JH13) that efficiently block progerin-lamin A/C binding. These 3 chemicals, particularly JH4, alleviated nuclear deformation and reversed senescence markers characteristic of HGPS cells, including growth arrest and senescence-associated β-gal (SA-β-gal) activity. We then used microarray-based analysis to demonstrate that JH4 is able to rescue defects of cell-cycle progression in both HGPS and aged cells. Furthermore, administration of JH4 to LmnaG609G/G609G-mutant mice, which phenocopy human HGPS, resulted in a marked improvement of several progeria phenotypes and an extended lifespan. Together, these findings indicate that specific inhibitors with the ability to block pathological progerin-lamin A/C binding may represent a promising strategy for improving lifespan and health in both HGPS and normal aging.

The aminoacyl tRNA synthetase complex-interacting multifunctional protein 2 (AIMP2) splice variant designated DX2 is induced by cigarette smoke carcinogens and is often detected in human lung cancer specimens. However, the function of DX2 in lung carcinogenesis is obscure. In this study, we found that DX2 expression was induced by oncogenes in human lung cancer tissues and cells. DX2 prevented oncogene-induced apoptosis and senescence and promoted drug resistance by directly binding to and inhibiting p14/ARF. Through chemical screening, we identified SLCB050, a novel compound that blocks the interaction between DX2 and p14/ARF in vitro and in vivo. SLCB050 reduced the viability of human lung cancer cells, especially small cell lung cancer cells, in a p14/ARF-dependent manner. Moreover, in a mouse model of K-Ras-driven lung tumorigenesis, ectopic expression of DX2 induced small cell and non-small cell lung cancers, both of which could be suppressed by SLCB050 treatment. Taken together, our findings show how DX2 promotes lung cancer progression and how its activity may be thwarted as a strategy to treat patients with lung cancers exhibiting elevated DX2 levels. Cancer Res; 76(16); 4791-804. Ó2016 AACR.

Since loss of VHL is frequently detected early phase genetic event in human renal cell carcinoma, pVHL is assumed to be indispensable for suppression of tumor initiation step. However, induction of HIF-1α, target of pVHL E3 ligase, is more adequate to angiogenesis step after tumor mass formation. Concerning this, it has been reported that pVHL is involved in centrosome location during metaphase and regulates ER-α signaling. Here, we provide the evidences that pVHL-mediated ER-α suppression is critical for microtubule organizing center (MTOC) maintaining and elevated ER-α promotes MTOC amplification through disruption of BRCA1-Rad51 interaction. In fact, numerous MTOC in VHL- or BRCA1-deficient cells are reduced by Fulvestrant, inhibitor of ER-α expression as well as antagonist. In addition, we reveal that activation of ER signaling can increase γ-tubulin, core factor of TuRC and render the resistance to Taxol. Thus, Fulvestrant but not Tamoxifen, antagonist against ER-α, can restore the Taxol sensitivity in VHL- or BRCA1-deficient cells. Our results suggest that pVHL-mediated ER-α suppression is important for regulation of MTOC as well as drug resistance.

Stress has been suggested as one of important cause of human cancer without molecular biological evidence. Thus, we test the effect of stress-related hormones on cell viability and mitotic fidelity. Similarly to estrogen, stress hormone cortisol and its relative cortisone increase microtubule organizing center (MTOC) number through elevated expression of γ-tubulin and provide the Taxol resistance to human cancer cell lines. However, these effects are achieved by glucocorticoid hormone receptor (GR) but not by estrogen receptor (ER). Since ginsenosides possess steroid-like structure, we hypothesized that it would block the stress or estrogen-induced MTOC amplification and Taxol resistance. Among tested chemicals, rare ginsenoside, CSH1 (Rg6) shows obvious effect on inhibition of MTOC amplification, γ-tubulin induction and Taxol resistance. Comparing to Fulvestant (FST), ER-α specific inhibitor, this chemical can block the cortisol/cortisone-induced MTOC deregulation as well as ER-α signaling. Our results suggest that stress hormone induced tumorigenesis would be achieved by MTOC amplification, and CSH1 would be useful for prevention of stresshormone or steroid hormone-induced chromosomal instability.

In recent, it has been reported that alternative splicing variant of AIMP2, AIMP2/DX2 (DX2), is frequently expressed in human lung cancer and is related with p53-mediated tumor suppression pathway. Here we show that DX2 can promote tumor progression and increase incidence, cooperatively with oncogenic K-Ras in transgenic mouse model. Moreover, it can induce small cell lung carcinoma (SCLC) as well as contribute to progression of non-small cell lung carcinoma (NSCLC). In fact, DX2 expression is elevated in human small cell lung cancer cell lines. Based on the cellular localization and responsibility of si-DX2, we revealed that DX2 is an inhibitor of p14/ARF. Elimination of DX2 can induce p14/ARF expression and DX2 Transgenic (Tg) mouse cells show the low expression of p19/ARF. Since DX2, but not its original product AIMP2, is selectively interacted with p14/ARF, we screened the specific binding inhibitor and obtained the single compound (SLC36) from about 9000 chemicals. This chemical can block the interaction of p14/ARF-DX2 and also AIMP2-DX2, but not the binding of p14/ARF-p53 or AIMP2-p53. In addition, it can induce p14/ARF expression and cell death in human lung cancer cell lines including SCLC cell lines. In our in vivo study, treatment of SLC36, combined with low dosage of adriamycin (1 mg/kg) can suppress the cancer incidence as well as progression in K-RasLA2 and K-Ras/DX2 double Tg model. These results indicate that DX2 can contribute to lung cancer progression and development, including SCLC, through inhibition of p14/ARF, and blocking of DX2-p14/ARF binding would be useful therapeutic strategy of human lung cancers including SCLC as well as NSCLC. Citation Format: Ah Young Oh, Youn-Sang Jung, Su-Jin Lee, Jung Hyun Jo, Ho Young Chun, Bum-Joon Park. Blocking of p14/ARF and DX2 binding by novel small chemical can improve the chemo-sensitivity of small cell lung cancer and non-small cell lung carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4602. doi:10.1158/1538-7445.AM2014-4602