GULP1 regulates the NRF2-KEAP1 signaling axis in urothelial carcinoma.

Disruption of the KEAP1-NRF2 pathway results in the transactivation of NRF2 target genes, consequently inducing cell proliferation and other phenotypic changes in cancer cells. Here, we demonstrated that GULP1 was a KEAP1-binding protein that maintained actin cytoskeleton architecture and helped KEAP1 to sequester NRF2 in the cytoplasm. In urothelial carcinoma of the bladder (UCB), silencing of GULP1 facilitated the nuclear accumulation of NRF2, led to constitutive activation of NRF2 signaling, and conferred resistance to the platinum drug cisplatin. Knockdown of GULP1 in UCB cells promoted tumor cell proliferation in vitro and enhanced tumor growth in vivo. In primary UCB, GULP1 silencing was more prevalent in muscle-invasive UCB compared to nonmuscle-invasive UCB. GULP1 knockdown cells showed resistance to cisplatin treatment. In parallel with decreased GULP1 expression, we observed increased expression of NRF2, HMOX1, and other candidate antioxidant genes in cisplatin-resistant cells. Furthermore, low or no expression of GULP1 was observed in most cisplatin nonresponder cases. Silencing of GULP1 was associated with GULP1 promoter hypermethylation in cell lines and primary tumors, and a high frequency of GULP1 promoter methylation was observed in multiple sets of primary clinical UCB samples. Together, our findings demonstrate that GULP1 is a KEAP1-binding protein that regulates KEAP1-NRF2 signaling in UCB and that promoter hypermethylation of GULP1 is a potential mechanism of GULP1 silencing.

MicroRNA expression profiling of Xp11 renal cell carcinoma.

Renal cell carcinomas (RCCs) with Xp11 translocation (Xp11 RCC) constitute a distinctive molecular subtype characterized by chromosomal translocations involving the Xp11.2 locus, resulting in gene fusions between the TFE3 transcription factor with a second gene (usually ASPSCR1, PRCC, NONO, or SFPQ). RCCs with Xp11 translocations comprise up to 1% to 4% of adult cases, frequently displaying papillary architecture with epithelioid clear cells. To better understand the biology of this molecularly distinct tumor subtype, we analyze the microRNA (miRNA) expression profiles of Xp11 RCC compared with normal renal parenchyma using microarray and quantitative reverse-transcription polymerase chain reaction. We further compare Xp11 RCC with other RCC histologic subtypes using publically available data sets, identifying common and distinctive miRNA signatures along with the associated signaling pathways and biological processes. Overall, Xp11 RCC more closely resembles clear cell rather than papillary RCC. Furthermore, among the most differentially expressed miRNAs specific for Xp11 RCC, we identify miR-148a-3p, miR-221-3p, miR-185-5p, miR-196b-5p, and miR-642a-5p to be up-regulated, whereas miR-133b and miR-658 were down-regulated. Finally, Xp11 RCC is most strongly associated with miRNA expression profiles modulating DNA damage responses, cell cycle progression and apoptosis, and the Hedgehog signaling pathway. In summary, we describe here for the first time the miRNA expression profiles of a molecularly distinct type of renal cancer associated with Xp11.2 translocations involving the TFE3 gene. Our results might help understanding the molecular underpinning of Xp11 RCC, assisting in developing targeted treatments for this disease.

Promoter methylation of MCAM, ERα and ERß in serum of early stage prostate cancer patients.

BACKGROUND: Prostate cancer (PC) is the second most common cancer among men worldwide. Currently, the most common non-invasive approach for screening and risk assessment of PC is measuring the level of serum prostate-specific antigen (PSA). However, the sensitivity of PSA is 42.8 % and specificity is 41.1%. As a result, the serum PSA test leads to numerous unneeded biopsies. Therefore, a rigorous search for biomarkers for early detection of PC is ongoing. In this study, we aim to assess a panel of epigenetic markers in an intend to develop an early detection test for PC. RESULTS: The sensitivity and specificity of hypermethylation of MCAM was 66% and 73% respectively which is an improvement from the sensitivity and specificity of PSA. Considering a combination marker panel of MCAM, ERα and ERß increased the sensitivity to 75% and the specificity became 70% for the minimally invasive early detection test of PC. MATERIALS AND METHODS: Sixteen primary matched tumor and serum were analyzed by quantitative methylation specific PCR (QMSP) to determine analytical and clinical sensitivity of the genes tested (SSBP2, MCAM, ERα, ERß, APC, CCND2, MGMT, GSTP1, p16 and RARß2). Additionally, serum samples from eighty four cases of PC, thirty controls and seven cases diagnosed as high grade Prostatic Intraepithelial Neoplasia (HGPIN) were analyzed. CONCLUSIONS: Promoter methylation of MCAM, ERα and ERß have a potential to be utilized as biomarker for the early detection of prostate PC as their sensitivity and specificity seem to be better than serum PSA in our cohort of samples. After robust validation in a larger prospective cohort, our findings may reduce the numbers of unwarranted prostate biopsies.

Nuclear and mitochondrial DNA alterations in newborns with prenatal exposure to cigarette smoke.

Newborns exposed to maternal cigarette smoke (CS) in utero have an increased risk of developing chronic diseases, cancer, and acquiring decreased cognitive function in adulthood. Although the literature reports many deleterious effects associated with maternal cigarette smoking on the fetus, the molecular alterations and mechanisms of action are not yet clear. Smoking may act directly on nuclear DNA by inducing mutations or epigenetic modifications. Recent studies also indicate that smoking may act on mitochondrial DNA by inducing a change in the number of copies to make up for the damage caused by smoking on the respiratory chain and lack of energy. In addition, individual genetic susceptibility plays a significant role in determining the effects of smoking during development. Furthermore, prior exposure of paternal and maternal gametes to cigarette smoke may affect the health of the developing individual, not only the in utero exposure. This review examines the genetic and epigenetic alterations in nuclear and mitochondrial DNA associated with smoke exposure during the most sensitive periods of development (prior to conception, prenatal and early postnatal) and assesses how such changes may have consequences for both fetal growth and development.

Peptide aptamers targeting mutant p53 induce apoptosis in tumor cells.

Mutations in the p53 tumor suppressor gene frequently result in expression of p53 point mutants that accumulate in cancer cells and actively collaborate with tumor progression through the acquisition of novel properties. Interfering with mutant p53 functions may represent a valid alternative for blocking tumor growth and development of aggressive phenotypes. The interactions and activities of selected proteins can be specifically modulated by the binding of peptide aptamers (PA). In the present work, we isolated PAs able to interact more efficiently with p53 conformational mutants compared with wild-type p53. The interaction between mutant p53 and PAs was further characterized using molecular modeling. Transient expression of PAs was able to reduce the transactivation activity of mutant p53 and to induce apoptosis specifically in cells expressing mutant p53. These PAs could provide a potential strategy to inhibit the oncogenic functions of mutant p53 and improve mutant p53-targeted cancer therapies.

The transcriptional repressor hDaxx potentiates p53-dependent apoptosis.

p53 and its homologues p73 and p63 are transcription factors that play an essential role in modulating cell cycle arrest and cell death in response to several environmental stresses. The type and intensity of these responses, which can be different depending on the inducing stimulus and on the overall cellular context, are believed to rely on the activation of defined subsets of target genes. The proper activation of p53 family members requires the coordinated action of post-translational modifications and interaction with several cofactors. In this study, we demonstrate that the multifunctional protein hDaxx interacts with p53 and its homologues, both in vitro and in vivo, and modulates their transcriptional activity. Moreover, we show that hDaxx, which has been implicated in several apoptotic pathways, increases the sensitivity to DNA damage-induced cell death and that this effect requires the presence of p53. Although hDaxx represses p53-dependent transcription of the p21 gene, it does not affect the activation of proapoptotic genes, and therefore acts by influencing the balance between cell cycle arrest and proapoptotic p53 targets. Our results therefore underline the central role of hDaxx in modulating the apoptotic threshold upon several stimuli and identify it as a possible integrating factor that coordinates the response of p53 family members.