Buffering of intracellular calcium in response to increased extracellular levels in mortal, immortal, and transformed human breast epithelial cells.

Extracellular levels of calcium at 1.05 mM or higher induce terminal differentiation and senescence in the mortal (MCF-10M) line of human breast epithelial cells, but does not retard the growth or induce differentiation in the immortal (MCF-10A) and oncogene transformed (MCF-10AneoT) lines. Intracellular levels of calcium and inositol triphosphate were determined in MCF-10M, MCF-10A, and MCF-10AneoT, under conditions of low and high extracellular calcium. We hereby report that increases in extracellular calcium is translated into significant increases in intracellular levels of calcium and inositol triphosphate in MCF-10M, but not in MCF-10A and MCF-10AneoT. This difference in the apparent calcium buffering capacity between the mortal and the immortalized human breast epithelial cells could account for the latter's unperturbed growth potential in high extracellular calcium environment.     

Molecular pathogenesis of malignant melanoma: a different perspective from the studies of melanocytic nevus and acral melanoma

The Clark model for melanoma progression emphasizes a series of histopathological changes beginning from benign melanocytic nevus to melanoma via dysplastic nevus. Several models of the genetic basis of melanoma development and progression are based on this Clark’s multi-step model, and predict that the acquisition of a BRAF mutation can be a founder event in melanocytic neoplasia. However, our recent investigations have challenged this view, showing the polyclonality of BRAF mutations in melanocytic nevi. Furthermore, it is suggested that many melanomas, including acral and mucosal melanomas, arise de novo, not from melanocytic nevus. While mutations of the BRAF gene are frequent in melanomas on non-chronic sun damaged skin which are prevalent in Caucasians, acral and mucosal melanomas harbor mutations of the KIT gene as well as the amplifications of cyclin D1 or cyclin-dependent kinase 4 gene. Amplifications of the cyclin D1 gene are detected in normal-looking ‘field melanocytes’, which represent a latent progression phase of acral melanoma that precedes the stage of atypical melanocyte proliferation in the epidermis. Based on these observations, we propose an alternative genetic progression model for melanoma.     

Cancer‐upregulated gene 2 (CUG2) overexpression induces apoptosis in SKOV‐3 cells

Cancer‐upregulated gene 2 (CUG2) was originally identified as a potential oncogene commonly up‐regulated in various human cancers. Recently, CUG2 was also identified as a new member of a centromere protein complex, important in the formation of a functional kinetochore complex. Presently, we report the pro‐apoptotic effect of CUG2 when this gene was overexpressed in the SKOV‐3 human ovarian cancer cell line. Apoptotic cell death mediated by CUG2 overexpression was independently demonstrated using cell viability determination, flow cytometry analysis, chromosome fragmentation assay, and the cleavage of the death substrate poly(ADP‐ribose) polymerase. Moreover, activation of caspase‐3 and ‐8 and the cytoplasmic translocation of mitochondrial cytochrome c were evident upon CUG2 expression. Apoptotic cell death was also observed during early development of zebrafish when CUG2 was overexpressed in zebrafish embryo. We propose that high expression of CUG2 induces apoptotic cell death. Copyright © 2010 John Wiley & Sons, Ltd.     

AMPH1 functions as a tumour suppressor in ovarian cancer via the inactivation of PI3K/AKT pathway

AMPH1, an abundant protein in nerve terminals, plays a critical role in the recruitment of dynamin to sites of clathrin‐mediated endocytosis. Recently, it is reported to be involved in breast cancer and lung cancer. However, the impact of AMPH1 on ovarian cancer is unclear. In this study, we used gain‐of‐function and loss‐of‐function methods to explore the role of AMPH1 in ovarian cancer cells. AMPH1 inhibited ovarian cancer cell growth and cell migration, and promoted caspase‐3 activity, resulting in the increase of cell apoptosis. In xenograft mice model, AMPH1 prevented tumour progression. The anti‐oncogene effects of AMPH1 on ovarian cancer might be partially due to the inhibition of PI3K/AKT signalling pathway after overexpression of AMPH1. Immunohistochemistry analysis showed that the staining of AMPH1 was remarkably reduced in ovarian cancer tissues compared with normal ovarian tissues. In conclusion, our study identifies AMPH1 as a tumour suppressor in ovarian cancer in vitro and in vivo. This is the first evidence that AMPH1 inhibited cell growth and migration, and induced apoptosis via the inactivation of PI3K/AKT signalling pathway on ovarian cancer, which may be used as an effective strategy.     

The synergy of germline C634Y and V292M RET mutations in a northern Chinese family with multiple endocrine neoplasia type 2A

Genetic analysis for germline mutations of RET proto‐oncogene has provided a basis for individual management of medullary thyroid carcinoma (MTC) and pheochromocytoma. Most of compound mutations have more aggressive phenotypes than single point mutations, but the compound C634Y/V292M variant in MTC has never been reported. Thus, we retrospectively investigated synergistic effect of C634Y and V292M RET germline mutations in family members with multiple endocrine neoplasia type 2A. Nine of 14 family members in a northern Chinese family underwent RET mutation screening using next‐generation sequencing and PCR followed by direct bidirectional DNA sequencing. Clinical features of nine individuals were retrospectively carefully reviewed. In vitro, the scratch‐wound assay was used to investigate the difference between the cells carrying different mutations. We find no patients died of MTC. All 3 carriers of the V292M variant were asymptomatic and did not have biochemical or structural evidence of disease (age: 82, 62 and 58). Among 4 C634Y mutation carriers, 2 patients had elevated calcitonin with the highest (156 pg/mL) in an 87‐year‐old male. Two carriers of compound C634Y/V292M trans variant had bilateral MTC with pheochromocytoma or lymph node metastasis (age: 54 and 41 years, respectively). Further, the compound C634Y/V292M variant had a faster migration rate than either single point mutation in vitro (P < .05). In conclusion, the V292M RET variant could be classified as ‘likely benign’ according to ACMG (2015). The compound variant V292M/C634Y was associated with both more aggressive clinical phenotype and faster cell growth in vitro than was either single mutation.     

A quantitative trait variant in Gabra2 underlies increased methamphetamine stimulant sensitivity

Psychostimulant (methamphetamine, cocaine) use disorders have a genetic component that remains mostly unknown. We conducted genome-wide quantitative trait locus (QTL) analysis of methamphetamine stimulant sensitivity. To facilitate gene identification, we employed a Reduced Complexity Cross between closely related C57BL/6 mouse substrains and examined maximum speed and distance traveled over 30 min following methamphetamine (2 mg/kg, i.p.). For maximum methamphetamine-induced speed following the second and third administration, we identified a single genome-wide significant QTL on chromosome 11 that peaked near the Cyfip2 locus (LOD = 3.5, 4.2; peak = 21 cM [36 Mb]). For methamphetamine-induced distance traveled following the first and second administration, we identified a genome-wide significant QTL on chromosome 5 that peaked near a functional intronic indel in Gabra2 coding for the alpha-2 subunit of the GABA-A receptor (LOD = 3.6–5.2; peak = 34–35 cM [66–67 Mb]). Striatal cis-expression QTL mapping corroborated Gabra2 as a functional candidate gene underlying methamphetamine-induced distance traveled. CRISPR/Cas9-mediated correction of the mutant intronic deletion on the C57BL/6J background to the wild-type C57BL/6NJ allele was sufficient to reduce methamphetamine-induced locomotor activity toward the wild-type C57BL/6NJ-like level, thus validating the quantitative trait variant (QTV). These studies show the power and efficiency of Reduced Complexity Crosses in identifying causal variants underlying complex traits. Functionally restoring Gabra2 expression decreased methamphetamine stimulant sensitivity and supports preclinical and human genetic studies implicating the GABA-A receptor in psychostimulant addiction-relevant traits. Importantly, our findings have major implications for studying psychostimulants in the C57BL/6J strain—the gold standard strain in biomedical research.     

The ortholog of the human proto‐oncogene ROS1 is required for epithelial development in C. elegans

The orphan receptor ROS1 is a human proto‐oncogene, mutations of which are found in an increasing number of cancers. Little is known about the role of ROS1, however in vertebrates it has been implicated in promoting differentiation programs in specialized epithelial tissues. In this study we show that the C. elegans ortholog of ROS1, the receptor tyrosine kinase ROL‐3, has an essential role in orchestrating the morphogenesis and development of specialized epidermal tissues, highlighting a potentially conserved function in coordinating crosstalk between developing epithelial cells. We also provide evidence of a direct relationship between ROL‐3, the mucin SRAP‐1, and BCC‐1, the homolog of mRNA regulating protein Bicaudal‐C. This study answers a longstanding question as to the developmental function of ROL‐3, identifies three new genes that are expressed and function in the developing epithelium of C. elegans, and introduces the nematode as a potentially powerful model system for investigating the increasingly important, yet poorly understood, human oncogene ROS1. genesis 51:545–561. © 2013 Wiley Periodicals, Inc.