The prognostic value of apoptotic and proliferative markers in breast cancer.

Increasing ability of early breast cancer (BC) diagnosis leading to more early stage detection, better survival, and low relapse marks one of the milestones achieved over the decades. Foregoing poses a challenge for clinicians regarding optimal treatment, in which over- and under-treatment should be avoided. Classical prognostic and predictive factors fall short for individualized adjuvant therapy selection in this patient group. The key to better characterization may be found in the biology underlying individual tumors. We hypothesized that markers related to cellular proliferation and apoptosis and the balance between these two processes in tumor development will be predictive for clinical outcome. Our study population (N = 822) consisted of all early stage BC patients primarily treated with surgery in our center between 1985 and 1996. Sections of available tumor tissue (87 %, 714/822) were immunohistochemically stained for expression of p53, active-caspase-3, and Ki67. In 43 % (304/714) and 18 % (126/714) of this cohort, respectively, a biochemical C2P(®) risk prediction and caspase-3 assay were performed. Expression data of the mentioned markers, single, or combined, were analyzed. Results showed that both the single and combined markers, whether of apoptotic or proliferative origin had associations with clinical outcome. An additive effect was seen for the hazard ratios when data on p53, active caspase-3, and Ki67 status were combined. The assembled prognostic apoptotic-proliferative subtype showed significant association for both the overall survival (p = 0.024) and relapse-free period (p = 0.001) in the multivariate analyses of grade I breast tumors. Combined markers of tumor cell apoptosis and proliferation represent tumor aggressiveness. The apoptotic-proliferative subtypes that we present in this study represent a clinical prognostic profile with solid underlying biological rationale and pose a promising method for accurate identification of grade I BC patients in need of an aggressive therapeutic approach, thus contributing to precision medicine in BC disease.

Polypyrimidine tract-binding protein regulates the cell cycle through IRES-dependent translation of CDK11(p58) in mouse embryonic stem cells.

Polypyrimidine tract-binding protein (PTB/PTBP1/hnRNP I) is a member of the heterogeneous nuclear ribonucleoprotein family that binds specifically to pyrimidine-rich sequences of RNAs. Although PTB is a multifunctional protein involved in RNA processing and internal ribosome entry site (IRES)-dependent translation, the role of PTB in early mouse development is unclear. Ptb knockout mice exhibit embryonic lethality shortly after implantation and Ptb-/- embryonic stem (ES) cells have a severe proliferation defect that includes a prolonged G2/M phase. The present study shows that PTB promotes M phase progression by the direct repression of CDK11(p58) IRES activity in ES cells. The protein expression and IRES activity of CDK11(p58) in Ptb-/- ES cells is higher than that of wild-type ES cells, indicating that PTB is involved in the repression of CDK11(p58) expression through IRES-dependent translation in ES cells. Interestingly, CDK11(p58) IRES activity is activated by upstream of N-Ras (UNR) in 293T and NIH3T3 cells, whereas UNR is not present in the Cdk11 mRNA-protein complex in ES cells. In addition, PTB interacts directly with the IRES region of CDK11(p58) in ES cells. These results suggest that PTB regulates the precise expression of CDK11(p58) through direct interaction with CDK11(p58) IRES and promotes M phase progression in ES cells.

Prediction of metastasis and recurrence in colorectal cancer based on gene expression analysis: ready for the clinic?

Cancers of the colon and rectum, which rank among the most frequent human tumors, are currently treated by surgical resection in locally restricted tumor stages. However, disease recurrence and formation of local and distant metastasis frequently occur even in cases with successful curative resection of the primary tumor (R0). Recent technological advances in molecular diagnostic analysis have led to a wealth of knowledge about the changes in gene transcription in all stages of colorectal tumors. Differential gene expression, or transcriptome analysis, has been proposed by many groups to predict disease recurrence, clinical outcome, and also response to therapy, in addition to the well-established clinico-pathological factors. However, the clinical usability of gene expression profiling as a reliable and robust prognostic tool that allows evidence-based clinical decisions is currently under debate. In this review, we will discuss the most recent data on the prognostic significance and potential clinical application of genome wide expression analysis in colorectal cancer.

Polypyrimidine tract-binding protein is essential for early mouse development and embryonic stem cell proliferation.

Polypyrimidine tract-binding protein (PTB) is a widely expressed RNA-binding protein with multiple roles in RNA processing, including the splicing of alternative exons, mRNA stability, mRNA localization, and internal ribosome entry site-dependent translation. Although it has been reported that increased expression of PTB is correlated with cancer cell growth, the role of PTB in mammalian development is still unclear. Here, we report that a homozygous mutation in the mouse Ptb gene causes embryonic lethality shortly after implantation. We also established Ptb(-/-) embryonic stem (ES) cell lines and found that these mutant cells exhibited severe defects in cell proliferation without aberrant differentiation in vitro or in vivo. Furthermore, cell cycle analysis and a cell synchronization assay revealed that Ptb(-/-) ES cells have a prolonged G(2)/M phase. Thus, our data indicate that PTB is essential for early mouse development and ES cell proliferation.

Fgf18 is required for embryonic lung alveolar development.

Fgf18 is abundantly expressed in mouse embryonic lungs. To elucidate the roles of Fgf18 in mouse embryonic lung development, we examined the Fgf18-/- embryonic lungs. Although the sizes of the Fgf18-/- lungs were a little smaller in appearance than those of wild-type lungs, neither proximal nor distal airway branching in the Fgf18-/- lungs was impaired. However, the Fgf18-/- lungs at E18.5 had reduced alveolar space, thicker interstitial mesenchymal compartments, and many embedded capillaries. Cell proliferation in the Fgf18-/- lungs was also transiently reduced around E17.5, although the expression of marker genes for lung epithelial cells in the Fgf18-/- lungs was not impaired. The present findings indicate that the Fgf18 plays roles in lung alveolar development during late embryonic lung development stages. The cell proliferation during the terminal saccular stage stimulated by Fgf18 might play roles in the remodeling of the distal lung.

FGF18 is required for normal cell proliferation and differentiation during osteogenesis and chondrogenesis.

Fibroblast growth factor (FGF) signaling is involved in skeletal development of the vertebrate. Gain-of-function mutations of FGF receptors (FGFR) cause craniosynostosis, premature fusion of the skull, and dwarfism syndromes. Disruption of Fgfr3 results in prolonged growth of long bones and vertebrae. However, the role that FGFs actually play in skeletal development in the embryo remains unclear. Here we show that Fgf18 is expressed in and required for osteogenesis and chondrogenesis in the mouse embryo. Fgf18 is expressed in both osteogenic mesenchymal cells and differentiating osteoblasts during calvarial bone development. In addition, Fgf18 is expressed in the perichondrium and joints of developing long bones. In calvarial bone development of Fgf18-deficient mice generated by gene targeting, the progress of suture closure is delayed. Furthermore, proliferation of calvarial osteogenic mesenchymal cells is decreased, and terminal differentiation to calvarial osteoblasts is specifically delayed. Delay of osteogenic differentiation is also observed in the developing long bones of this mutant. Conversely, chondrocyte proliferation and the number of differentiated chondrocytes are increased. Therefore, FGF18 appears to regulate cell proliferation and differentiation positively in osteogenesis and negatively in chondrogenesis.