Idiopathic pulmonary fibrosis (IPF) is a serious progressive and irreversible lung disease with unknown etiology and few treatment options. This disease was once thought to be a chronic inflammatory-driven process, but it is increasingly recognized that the epithelial–mesenchymal transition (EMT) contributes to the cellular origin of fibroblast accumulation in response to injury. During the pathogenesis of pulmonary fibrotic diseases, transforming growth factor-β (TGF-β) signaling is considered a pivotal inducer of EMT and fibroblast activation, and a number of therapeutic interventions that interfere with TGF-β signaling have been developed to reverse established fibrosis. However, efficient and well-tolerated antifibrotic agents are not currently available. Previously, we reported the identification of sorafenib to antagonize TGF-β signaling in mouse hepatocytes in vitro. In this manuscript, we continued to evaluate the antifibrotic effects of sorafenib on bleomycin (BLM)-induced pulmonary fibrosis in mice. We further demonstrated that sorafenib not only profoundly inhibited TGF-β1-induced EMT in alveolar epithelial cells, but also simultaneously reduced the proliferation and collagen synthesis in fibroblasts. Additionally, we presented in vivo evidence that sorafenib inhibited the symptoms of BLM-mediated EMT and fibroblast activation in mice, warranting the therapeutic potential of this drug for patients with IPF.

The cytoplasmic level of heterogeneous nuclear ribonucleoprotein K (hnRNP K) is significantly correlated with the elevated expression of thymidine phosphorylase (TP), and high levels of both proteins are predictive of a poor prognosis in nasopharyngeal carcinoma (NPC). We herein show that TP is highly induced by serum deprivation in NPC cells, and that this is due to an increase in the halflife of the TP mRNA, as shown by nuclear run-on and actinomycin D assays. We further show that the CU-rich element of the TP mRNA directly interacts with hnRNP K, as demonstrated by immunoprecipitation RT-PCR assays, and the nucleus-to-cytoplasm translocation of hnRNP K. Blockade of hnRNP K expression reduces TP expression, suggesting that hnRNP K acts in the upregulation of TP. Mechanistically, both MEK inhibitor and the hnRNP K ERK-phosphoacceptor-site mutant decrease cytoplasmic accumulation of hnRNP K, suggesting that ERK-dependent phosphorylation is critical for TP induction. Furthermore, we found that hnRNP Kmediated TP induction allows NPC cells to resist hypoxia-induced apoptosis. Our results collectively establish the regulation and role of ERK-mediated cytoplasmic accumulation of hnRNP K as an upstream modulator of TP, suggesting that hnRNP K may be an attractive candidate as a future therapeutic target for cancer.

Zinc finger protein 687 (ZNF687), identified as a C2H2 zinc finger protein, has been found to be mutated and upregulated in giant cell tumor of bone and acute myeloid leukemia, suggesting an oncogenic role for ZNF687 in cancer. However, the clinical significance and precise role of ZNF687 in cancer progression are largely unknown. Herein, we report that ZNF687 was markedly upregulated in hepatocellular carcinoma (HCC) cell lines and HCC tissues, and was significantly correlated with relapse-free survival in HCC. ZNF687 overexpression greatly enhanced HCC cell capability for tumorsphere formation, invasion and chemoresistance in vitro, whereas inhibiting ZNF687 reduced these capabilities and inhibited HCC cell tumorigenic capability in vivo. Importantly, extreme limiting dilution analysis revealed that even 1 × 102 ZNF687-transduced cells could form tumors in vivo, indicating that ZNF687 contributes to HCC recurrence. Moreover, we demonstrate that ZNF687 transcriptionally upregulated the expression of the pluripotency-associated factors BMI1, OCT4 and NANOG by directly targeting their promoters. Therefore, our results suggest that ZNF687 has a promoter role in regulating HCC progression, which provides a potential therapeutic target for HCC in humans.

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