Cell Cycle-Dependent TICRR/TRESLIN and MTBP Chromatin Binding Mechanisms and Patterns.

The selection of replication origins is a defining characteristic of DNA replication in eukaryotes, yet its mechanism in humans has not been well-defined. In this study, we use Cut&Run to examine genomic binding locations for TICRR/TRESLIN and MTBP, the human orthologs for the yeast DNA replication initiation factors Sld3 and Sld7. We mapped TRESLIN and MTBP binding in HCT116 colorectal cancer cells using asynchronous and G1 synchronized populations. Our data show that TRESLIN and MTBP binding patterns are more defined in a G1 synchronized population compared to asynchronously cycling cells. We also examined whether TRESLIN and MTBP are dependent on one another for binding. Our data suggest MTBP is dependent on TRESLIN for proper association with chromatin during G1 but not S phase. Finally, we asked whether TRESLIN and MTBP binding to chromatin requires licensed origins. Using cell lines with a non-degradable inducible Geminin to inhibit licensing, we show TRESLIN and MTBP binding does not require loaded MCMs. Altogether, our Cut&Run data provides evidence for a chromatin binding mechanism of TRESLIN-MTBP during G1 that is dependent on TRESLIN and does not require interactions with licensed origins.

High incidence of FLT3 mutations in follicular thyroid cancer: potential therapeutic target in patients with advanced disease stage.

BACKGROUND: Conventional treatments for follicular thyroid cancer (FTC) can be ineffective, leading to poor prognosis. The aim of this study was to identify mutations associated with FTC that would serve as novel molecular markers of the disease and its outcome and could potentially identify new therapeutic targets. METHODS: FLT3 mutations were first detected in a 29-year-old White female diagnosed with metastasized, treatment-refractory FTC. Analyses of FLT3 mutational status through next-generation sequencing of formalin-fixed, paraffin-embedded FTC specimens were subsequently performed in 35 randomly selected patients diagnosed with FTC. RESULTS: FLT3 mutations were found in 69% of patients. FLT3 mutation-positive patients were significantly older than those that were FLT3 mutation-negative [median age at diagnosis 54 (36-82) versus 45 (27-58) (p = 0.023)]. Patients over 60 years were 23 times more likely to be FLT3 mutation-positive (p = 0.006). However, the number of FLT3 mutations did not correlate with age (r-Pearson: -0.244, p-value: 0.25). A total of 26 mutations were identified in the FLT3 gene with 2-16 FLT3 mutations in each FLT3 mutation-positive patient (mean: 5.6 mutations/patient). Tyrosine kinase domain (TKD) mutations in the FLT3 gene were detected in 58% of FLT3 mutation-positive patients. All FLT3 mutation-positive patients with a disease stage of pT2N1 or worse harbored at least one mutation in the TKD of FLT3. CONCLUSIONS: There is a wide spectrum and high frequency of FLT3 mutations in FTC. The precise role of FLT3 mutations in the genesis of FTC, as well as its potential role as a therapeutic target, requires further investigation.

A mechanism for epigenetic control of DNA replication.

DNA replication origins in hyperacetylated euchromatin fire preferentially during early S phase. However, how acetylation controls DNA replication timing is unknown. TICRR/TRESLIN is an essential protein required for the initiation of DNA replication. Here, we report that TICRR physically interacts with the acetyl-histone binding bromodomain (BRD) and extraterminal (BET) proteins BRD2 and BRD4. Abrogation of this interaction impairs TICRR binding to acetylated chromatin and disrupts normal S-phase progression. Our data reveal a novel function for BET proteins and establish the TICRR-BET interaction as a potential mechanism for epigenetic control of DNA replication.

Genomic markers of ovarian adenocarcinoma and its relevancy to the effectiveness of chemotherapy.

Ovarian cancer is the eighth most common cancer and the seventh highest cause of cancer-associated mortality in women worldwide. It is the second highest cause of mortality among female reproductive malignancies. The current standard first-line treatment for advanced ovarian cancer includes a combination of surgical debulking and standard systemic platinum-based chemotherapy with carboplatin and paclitaxel. Although a deeper understanding of this disease has been attained, relapse occurs in 70% of patients 18 months subsequent to the first-line treatment. Therefore, it is crucial to develop a novel drug that effectively affects ovarian cancer, particularly tumors that are resistant to current chemotherapy. The aim of the present study was to identify genes whose expression may be used to predict survival time or prognosis in ovarian cancer patients treated with chemotherapy. Gene or protein expression is an important issue in chemoresistance and survival prediction in ovarian cancer. In the present study, the research group consisted of patients treated at the Surgical Clinic of the Gynecology and Obstetrics Gynecological Clinical Hospital, Poznan University of Medical Sciences (Poznan, Poland) between May 2006 and November 2014. Additional eligibility criteria were a similar severity (International Federation of Gynecolgy and Obstetrics stage III) at the time of diagnosis, treatment undertaken in accordance with the same schedule, and an extremely good response to treatment or a lack of response to treatment. The performance of the OncoScan® assay was evaluated by running the assay on samples obtained from the four patients and by following the recommended protocol outlined in the OncoScan assay manual. The genomic screening using Affymetrix OncoScan Arrays resulted in the identification of large genomic rearrangements across all cancer tissues. In general, chromosome number changes were detected in all examined tissues. The OncoScan arrays enabled the identification of ~100 common somatic mutations. Chemotherapy response in ovarian cancer is extremely complex and challenging to study. The present study identified specific genetic alterations associated with ovarian cancer, but not with response for treatment.