Loss of the transcription repressor ZHX3 induces senescence-associated gene expression and mitochondrial-nucleolar activation

Clinical and molecular cytogenetic studies of five new patients with 20q11q12 deletion and review of the literature: Proposition of two critical regions

Deletions of the long arm of chromosome 20 (20q) are rare, with only 16 reported patients displaying a proximal interstitial 20q deletion. A 1.62 Mb minimal critical region at 20q11.2, encompassing three genes GDF5, EPB41L1, and SAMHD1, is proposed to be responsible for this syndrome. The leading clinical features include growth retardation, intractable feeding difficulties with gastroesophageal reflux, hypotonia and psychomotor developmental delay. Common facial dysmorphisms including triangular face, hypertelorism, and hypoplastic alae nasi were additionally reported. Here, we present the clinical and molecular findings of five new patients with proximal interstitial 20q deletions. We analyzed the phenotype and molecular data of all previously reported patients with 20q11.2q12 microdeletions, along with our five new cases. Copy number variation analysis of patients in our cohort has enabled us to identify the second critical region in the 20q11.2q12 region and redefine the first region that is initially identified. The first critical region spans 359 kb at 20q11.2, containing six MIM genes, including two disease-causing genes, GDF5 and CEP250. The second critical region spans 706 kb at 20q12, encompassing four MIM genes, including two disease-causing genes, MAFB and TOP1. We propose GDF5 to be the primary candidate gene generating the phenotype of patients with 20q11.2 deletions. Moreover, we hypothesize TOP1 as a potential candidate gene for the second critical region at 20q12. Of note, we cannot exclude the possibility of a synergistic role of other genes involved in the deletion, including a contiguous gene deletion syndrome or position effect affecting both critical regions. Further studies focusing on patients with proximal 20q deletions are required to support our hypothesis.

Low expression of ZHX3 is associated with progression and poor prognosis in colorectal cancer

Accumulating studies suggest that ZHX3, the member of ZHX family, is involved in a variety of biological functions such as development and differentiation. Recently, ZHX3 may also be involved in the progression of several cancer types including renal cancer, gastric cancer, liver cancer and breast cancer. However, the potential role of ZHX3 in colorectal cancer (CRC) is still unknown. In this study, we analyzed the protein levels of ZHX3 by immunohistochemistry and evaluated its relationship with the clinicopathological features and prognosis in 286 CRC patients. In vitro cell proliferation assay, plate colony formation assay and xenograft model in nude mice were applied to evaluate CRC cell proliferative ability. Our results showed that the expression of ZHX3 was significantly downregulated in CRC tissues compared with paired adjacent nontumor tissues. Furthermore, the ZHX3 expression was found to have a strong correlation with tumor size, tumor invasion depth and TNM stage. Kaplan-Meier analysis demonstrated that low ZHX3 expression was related to a poorer overall survival and disease-free survival in CRC patients. In addition, cox's proportional hazards analysis indicated that low ZHX3 expression was an independent prognostic indicator of poor prognosis. Functionally, reduced expression of ZHX3 promotes the proliferation of CRC cells both in vitro and in vivo. Conversely, overexpression of ZHX3 inhibited the growth of CRC cells, indicated that ZHX3 was significantly correlated with CRC progression. Our results indicate for the first time that ZHX3 may be a potential marker of cancer prognosis and CRC recurrence.

The Role of Antioxidants in the Interplay between Oxidative Stress and Senescence

Cellular senescence is an irreversible state of cell cycle arrest occurring in response to stressful stimuli, such as telomere attrition, DNA damage, reactive oxygen species, and oncogenic proteins. Although beneficial and protective in several physiological processes, an excessive senescent cell burden has been involved in various pathological conditions including aging, tissue dysfunction and chronic diseases. Oxidative stress (OS) can drive senescence due to a loss of balance between pro-oxidant stimuli and antioxidant defences. Therefore, the identification and characterization of antioxidant compounds capable of preventing or counteracting the senescent phenotype is of major interest. However, despite the considerable number of studies, a comprehensive overview of the main antioxidant molecules capable of counteracting OS-induced senescence is still lacking. Here, besides a brief description of the molecular mechanisms implicated in OS-mediated aging, we review and discuss the role of enzymes, mitochondria-targeting compounds, vitamins, carotenoids, organosulfur compounds, nitrogen non-protein molecules, minerals, flavonoids, and non-flavonoids as antioxidant compounds with an anti-aging potential, therefore offering insights into innovative lifespan-extending approaches.