The role of PTPRK and PTPRM in prostate and breast cancer

Protein tyrosine phosphatases (PTPs) have been identified that mediate a range of physiological and pathological processes, such as proliferation and tumour metastasis. PTPRK and PTPRM belong to the same subfamily of PTPs. This study aims to investigate the role of PTPRK and PTPRM in cancer development and progression. Knockdown of PTPRK expression was performed in PC-3 and DU-145 cells. Functional assays were then carried out on these cells in order to determine any changes in their biological properties. Knockdown of PTPRK significantly reduced the growth and adhesion of both PC-3 and DU-145 cells. The experimental results suggested that reduction of cell growth is potential involvement of p53 and/or caspase-3 and -8 and its up-stream molecule JNK. The decreased expression of PTPRK and PTPRM are associated with poor prognosis and reduced survival. Knockdown of PTPRK resulted in increased adhesive and invasive abilities, and promoted cell proliferation and motility of breast cancer cells. Moreover, PTPRM knockdown resulted in elevated adhesion, invasion, and proliferation of breast cancer cells. Activation of ERK and JNK by tyrosine phosphorylation and consequent elevated MMP9 activity is involved in increased cell migration and invasion by PTPRM knockdown. These results suggested that PTPRK and PTPRM are involved in the disease progression of prostate and breast cancer by regulating a complex network of pathways and molecules. This provides further proof of the importance of the R2B subfamily, a subgroup of PTP superfamily, in cancer. In addition, it sheds some light on the use of PTPs as prognostic indicators of disease, aiding in diagnosis and treatment. The major effect is the promotion of motility and invasiveness of cancer cells via ERK and JNK pathways. However it can also impair the apoptosis mediated by JNK pathways in certain cancer cells, such as prostate cancer cells. Such contrasting effects on survival and motility require further investigation, and should also be considered when treating cancers by targeting these molecules

Dual roles of protein tyrosine phosphatase kappa in coordinating angiogenesis induced by pro-angiogenic factors

A potential role may be played by receptor-type protein tyrosine phosphatase kappa (PTPRK) in angiogenesis due to its critical function in coordinating intracellular signal transduction from various receptors reliant on tyrosine phosphorylation. In the present study, we investigated the involvement of PTPRK in the cellular functions of vascular endothelial cells (HECV) and its role in angiogenesis using in vitro assays and a PTPRK knockdown vascular endothelial cell model. PTPRK knockdown in HECV cells (HECVPTPRKkd) resulted in a decrease of cell proliferation and cell-matrix adhesion; however, increased cell spreading and motility were seen. Reduced focal adhesion kinase (FAK) and paxillin protein levels were seen in the PTPRK knockdown cells which may contribute to the inhibitory effect on adhesion. HECVPTPRKkd cells were more responsive to the treatment of fibroblast growth factor (FGF) in their migration compared with the untreated control and cells treated with VEGF. Moreover, elevated c-Src and Akt1 were seen in the PTPRK knockdown cells. The FGF-promoted cell migration was remarkably suppressed by an addition of PLCγ inhibitor compared with other small inhibitors. Knockdown of PTPRK suppressed the ability of HECV cells to form tubules and also impaired the tubule formation that was induced by FGF and conditioned medium of cancer cells. Taken together, it suggests that PTPRK plays dual roles in coordinating angiogenesis. It plays a positive role in cell proliferation, adhesion and tubule formation, but suppresses cell migration, in particular, the FGF-promoted migration. PTPRK bears potential to be targeted for the prevention of tumour associated angiogenesis

Dynamic Evolution of Eukaryotic Mitochondrial and Nuclear Genomes: A Case Study in the Gourmet Pine Mushroom Tricholoma matsutake

Fungi, as eukaryotic organisms, contain two genomes, the mitochondrial genome and the nuclear genome, in their cells. How the two genomes evolve and correlate to each other is debated. Herein, taking the gourmet pine mushroom Tricholoma matsutake as an example, we performed comparative mitogenomic analysis using samples collected from diverse locations and compared the evolution of the two genomes. The T. matsutake mitogenome encodes 49 genes and is rich of repetitive and non-coding DNAs. Six genes were invaded by up to 11 group I introns, with one cox1 intron cox1P372 showing presence/absence dynamics among different samples. Bioinformatic analyses suggested limited or no evidence of mitochondrial heteroplasmy. Interestingly, hundreds of mitochondrial DNA fragments were found in the nuclear genome, with several larger than 500 nt confirmed by PCR assays and read count comparisons, indicating clear evidence of transfer of mitochondrial DNA into the nuclear genome. Nuclear DNA of T. matsutake showed a higher mutation rate than mitochondrial DNA. Furthermore, we found evidence of incongruence between phylogenetic trees derived from mitogenome and nuclear DNA sequences. Together, our results reveal the dynamic genome evolution of the gourmet pine mushroom.Peer reviewe