The inverted CCAAT motif is an indispensable element of the enhancer B of the mouse major histocompatibility I H2-Kb gene

Thymidine kinase 1 through the ages: a comprehensive review

Proliferation markers, such as proliferating cell nuclear antigen (PCNA), Ki-67, and thymidine kinase 1 (TK1), have potential as diagnostic tools and as prognostic factors in assessing cancer treatment and disease progression. TK1 is involved in cellular proliferation through the recovery of the nucleotide thymidine in the DNA salvage pathway. TK1 upregulation has been found to be an early event in cancer development. In addition, serum levels of TK1 have been shown to be tied to cancer stage, so that higher levels of TK1 indicate a more serious prognosis. As a result of these findings and others, TK1 is not only a potentially viable biomarker for cancer recurrence, treatment monitoring, and survival, but is potentially more advantageous than current biomarkers. Compared to other proliferation markers, TK1 levels during S phase more accurately determine the rate of DNA synthesis in actively dividing tumors. Several reviews of TK1 elaborate on various assays that have been developed to measure levels in the serum of cancer patients in clinical settings. In this review, we include a brief history of important TK1 discoveries and findings, a comprehensive overview of TK1 regulation at DNA to protein levels, and recent findings that indicate TK1’s potential role in cancer pathogenesis and its growing potential as a tumor biomarker and therapeutic target.

An extended pyrrolobenzodiazepine-polyamide conjugate with selectivity for a DNA sequence containing the ICB2 transcription factor binding site

The binding of nuclear factor Y (NF-Y) to inverted CCAAT boxes (ICBs) within the promoter region of DNA topoisomerase IIα results in control of cell differentiation and cell cycle progression. Thus, NF-Y inhibitory small molecules could be employed to inhibit the replication of cancer cells. A library of pyrrolobenzodiazepine (PBD) C8-conjugates consisting of one PBD unit attached to tri-heterocyclic polyamide fragments was designed and synthesized. The DNA-binding affinity and sequence selectivity of each compound were evaluated in DNA thermal denaturation and DNase I footprinting assays, and the ability to inhibit binding of NF-Y to ICB1 and ICB2 was studied using an electrophoretic mobility shift assay (EMSA). 3a was found to be a potent inhibitor of NF-Y binding, exhibiting a 10-fold selectivity for an ICB2 site compared to an ICB1-containing sequence, and showing low nanomolar cytotoxicity toward human tumor cell lines. Molecular modeling and computational studies have provided details of the covalent attachment process that leads to formation of the PBD-DNA adduct, and have allowed the preference of 3a for ICB2 to be rationalized.

Jun oncoproteins do not function as primary transcription factors for the mouse major histocompatibility complex class I H-2 genes in fibroblasts

There are several reports in the literature focusing on regulation of major histocompatibility complex (MHC) class I genes by transcription factors of the jun family. The methods employed in these reports differed in various respects, and their results are inconsistent. In mouse Lewis lung carcinoma, B16-melanoma and F9-teratocarcinoma cell lines, c-jun was characterized as a transcriptional activator of the murine MHC class I H2-Kb gene, while c-jun was identified as a direct transcriptional repressor of the swine class I PD1 gene, and c-jun stably transfected clones of mouse L-fibroblasts markedly reduced their H-2 class I gene expression. In this study, we attempted to reproduce this last effect by means of transient transfection coupled to Northern hybridization, upon transfecting L-fibroblasts with expression vectors for all jun family members as well as with an array of c-jun-derived dominant negative mutants. No change in H-2 class I expression could be identified. Next, we derived two additional fibroblastic cell lines from the fibrosarcoma of the H2-Kk/v-jun transgenic mouse and transfected them with the two most potent c-jun dominant negative mutants, again without eliciting any change in H-2 class I mRNA level. We conclude that the negative regulation of H-2 class I genes by c-jun in cells of the fibroblastic lineage is not a primary effect.