Jiahui Zhao

Bio: Jiahui Zhao is an academic researcher from Capital Medical University. The author has contributed to research in topics: LNCaP & Epithelial–mesenchymal transition. The author has an hindex of 9, co-authored 25 publications receiving 237 citations.

Knockdown of β-Catenin Through shRNA Cause a Reversal of EMT and Metastatic Phenotypes Induced by HIF-1α

Abstract: Obective: Wnt/β-catenin signaling pathway regulates pattern formation during embryogenesis as well as tumor progression. Numbers of studies suggest that this signaling pathway may play an important role in Epithelial-Mesenchymal transition (EMT), however, there was no evidence that Wnt/β-catenin signaling pathway directly controlled the EMT occurrence. Our previous research has successfully proved that overexpression of hypoxia inducible factor-1α (HIF-1α) could induce EMT in LNCaP cells, but not in PC-3. Consistently, the expression of β-catenin protein increased in LNCaP/HIF-1α cells, but not in PC-3/HIF-1α. This study mainly aimed at exploring the essentiality and importance of Wnt/β-catenin signaling pathway in HIF-1α-induced EMT. Methods: Human prostate cancer cells (LNCaP) were stably transfected by recombinant plasmid pcDNA3.1(-)/HIF-1α. The positive clones were selected by G418 and confirmed through western blot analysis, reverse transcription-polymerase chain reaction (RT-PCR), and indirect immun...

Epithelial-Mesenchymal Transition and Migration of Prostate Cancer Stem Cells Is Driven by Cancer-Associated Fibroblasts in an HIF-1α/β-Catenin-Dependent Pathway

Abstract: Although cancer stem cells (CSCs) play a crucial role in seeding the initiation of tumor progression, they do not always possess the same potent ability as tumor metastasis. Thus, precisely how migrating CSCs occur, still remains unclear. In the present study, we first comparatively analyzed a series of prostate CSCs, which exhibited a dynamically increasing and disseminating ability in nude mice. We observed that the transcriptional activity of HIF-1α and β-catenin became gradually elevated in these stem cells and their epithelial-mesenchymal transition (EMT) characteristic altered from an epithelial type to a mesenchymal type. Next, we further used cancer-associated fibroblasts (CAFs), which were cultured from surgically resected tissues of prostate cancer (PCa) to stimulate prostate CSCs. Similar results were reconfirmed and showed that the protein levels of both HIF-1α and β-catenin were markedly improved. In addition, the EMT phenotype displayed a homogenous mesenchymal type, accompanied with increased aggressive potency in vitro. Most importantly, the aforementioned promoting effect of CAFs on prostate CSCs was completely repressed after “silencing” the activity of β-catenin by transfection of stem cells with ShRNA. Taken together, our observations suggest that prostate migrating CSCs, with a mesenchymal phenotype, could be triggered by CAFs in a HIF-1α/β-catenin-dependent signaling pathway.

β‑catenin nuclear translocation induced by HIF‑1α overexpression leads to the radioresistance of prostate cancer

Abstract: Hypoxia-inducible factor-1 alpha (HIF-1 alpha) is known to play crucial roles in tumor radioresistance; however, the molecular mechanisms responsible for the promotion of tumor radioresistance by HIF-1 alpha remain unclear beta-catenin is known to be involved in the metastatic potential of prostate cancer (PCa). In this study, to investigate the role of HIF-1 alpha and beta-catenin in the radioresistance of PCa, two PCa cell lines, LNCaP and C4-2B, were grouped as follows: Negative control (no treatment), HIF-1 alpha overexpression group (transfected with HIF-1 alpha overexpression plasmid) and beta-catenin silenced group (transfected with HIF-1 alpha plasmids and beta-catenin-shRNA). Cell proliferation, cell cycle, cell invasion and radiosensitivity were examined under normal or hypoxic conditions. In addition, radiosensitivity was examined in two mouse PCa models (the LNCaP orthotopic BALB/c-nu mice model and the C4-2B subcutaneous SCID mice model). Our results revealed that in both the LNCaP and C4-2B cells, transfection with HIF-1 alpha overexpression plasmid led to an enhanced beta-catenin nuclear translocation, while beta-catenin silencing inhibited beta-catenin nuclear translocation. The enhanced beta-catenin nuclear translocation induced by HIF-1 alpha overexpression resulted in an enhanced cell proliferation and cell invasion, an altered cell cycle distribution, decreased apoptosis, and improved non-homologous end joining (NHEJ) repair under normal and irradiation conditions. Similar results were observed in the animal models. HIF-1 alpha overexpression enhanced beta-catenin nuclear translocation, which led to the activation of the beta-catenin/NHEJ signaling pathway and increased cell proliferation, cell invasion and DNA repair. These results thus suggest that HIF-1 alpha overexpression promotes the radioresistance of PCa cells.

Cells susceptible to epithelial-mesenchymal transition are enriched in stem-like side population cells from prostate cancer.

Abstract: Accumulating evidence suggests that epithelial-mesenchymal transition (EMT) acts as an important factor for the promotion of tumor progression. Strategies for suppressing EMT remain the subject of ongoing research. In the present study, fluorescence-activated cell sorting (FACS) was used to isolate side population (SP) cells from human prostate cancer (PCa) cell lines and xenograft tissues. After identifying their molecular and functional stem-like characteristics, stem-like SP cells from a cell line and from xenograft tissue were transfected with hypoxia inducible factor-1α (HIF-1α). The potential of the prostate stem-like SP cells to undergo EMT was compared with that in their bulk counterparts after HIF-1α introduction. Stem-like SP cells acquired more complete EMT molecular features and exhibited stronger aggressive capability than the homologous bulk population cells both in vitro (proliferation and invasion) and in vivo (tumorigenesis and metastasis formation). We, therefore, concluded that EMT is closely associated with tumor heterogeneity, and that PCa cells susceptible to EMT are enriched in stem-like SP cells. These findings disclose a new approach, targeting the cellular basis of the EMT process that may help to identify effective and accurate methods for suppressing tumor growth and preventing distant dissemination.

Hypoxia inducible factor-1α-dependent epithelial to mesenchymal transition under hypoxic conditions in prostate cancer cells.

Abstract: Prostate cancer is the most commonly diagnosed cancer in men and the second leading cause of cancer death. Hypoxia is an environmental stimulus that plays an important role in the development and cancer progression especially for solid tumors. The key regulator under hypoxic conditions is stabilized hypoxia-inducible factor (HIF)-1α. In the present study, immune-fluorescent staining, siRNAs, qRT-PC, immunoblotting, cell migration and invasion assays were carried out to test typical epithelial to mesenchymal transition under hypoxia and the key regulators of this process in PC3, a human prostate cancer cell line. Our data demonstrated that hypoxia induces diverse molecular, phenotypic and functional changes in prostate cancer cells that are consistent with EMT. We also showed that a cell signal factor such as HIF-1α, which might be stabilized under hypoxic environment, is involved in EMT and cancer cell invasive potency. The induced hypoxia could be blocked by HIF-1α gene silencing and reoxygenation of EMT in prostate cancer cells, hypoxia partially reversed accompanied by a process of mesenchymal-epithelial reverting transition (MErT). EMT might be induced by activation of HIF-1α-dependent cell signaling in hypoxic prostate cancer cells.

TCF/LEFs and Wnt Signaling in the Nucleus

Abstract: T-cell factor/lymphoid enhancer factor (TCF/LEF) transcription factors are the major end point mediators of Wnt/Wingless signaling throughout metazoans. TCF/LEFs are multifunctional proteins that use their sequence-specific DNA-binding and context-dependent interactions to specify which genes will be regulated by Wnts. Much of the work to define their actions has focused on their ability to repress target gene expression when Wnt signals are absent and to recruit β-catenin to target genes for activation when Wnts are present. Recent advances have highlighted how these on/off actions are regulated by Wnt signals and stabilized β-catenin. In contrast to invertebrates, which typically contain one TCF/LEF protein that can both activate and repress Wnt targets, gene duplication and isoform complexity of the family in vertebrates have led to specialization, in which individual TCF/LEF isoforms have distinct activities.

Mesenchymal-to-epithelial transition facilitates bladder cancer metastasis : role of fibroblast growth factor receptor-2

Abstract: Epithelial-to-mesenchymal transition (EMT) increases cell migration and invasion, and facilitates metastasis in multiple carcinoma types, but belies epithelial similarities between primary and secondary tumors. This study addresses the importance of mesenchymal-to-epithelial transition (MET) in the formation of clinically significant metastasis. The previously described bladder carcinoma TSU-Pr1 (T24) progression series of cell lines selected in vivo for increasing metastatic ability following systemic seeding was used in this study. It was found that the more metastatic sublines had acquired epithelial characteristics. Epithelial and mesenchymal phenotypes were confirmed in the TSU-Pr1 series by cytoskeletal and morphologic analysis, and by performance in a panel of in vitro assays. Metastatic ability was examined following inoculation at various sites. Epithelial characteristics associated with dramatically increased bone and soft tissue colonization after intracardiac or intratibial injection. In contrast, the more epithelial sublines showed decreased lung metastases following orthotopic inoculation, supporting the concept that EMT is important for the escape of tumor cells from the primary tumor. We confirmed the overexpression of the IIIc subtype of multiple fibroblast growth factor receptors (FGFR) through the TSU-Pr1 series, and targeted abrogation of FGFR2IIIc reversed the MET and associated functionality in this system and increased survival following in vivo inoculation in severe combined immunodeficient mice. This model is the first to specifically model steps of the latter part of the metastatic cascade in isogenic cell lines, and confirms the suspected role of MET in secondary tumor growth.

Cancer-associated fibroblasts as another polarized cell type of the tumor microenvironment.

Abstract: Tumor- or cancer-associated fibroblasts (CAFs) are one of the most abundant stromal cell types in different carcinomas and comprise a heterogeneous cell population. Classically, CAFs are assigned with pro-tumorigenic effects stimulating tumor growth and progression. More recent studies demonstrated also tumor-inhibitory effects of CAFs suggesting that tumor-residing fibroblasts exhibit a similar degree of plasticity as other stromal cell types. Reciprocal interactions with the tumor milieu and different sources of origin are emerging as two important factors underlying CAF heterogeneity. This review highlights recent advances in our understanding of CAF biology and proposes to expand the term of cellular ´polarization´, previously introduced to describe different activation states of various immune cells, onto CAFs to reflect their phenotypic diversity.

HIF-1 at the crossroads of hypoxia, inflammation, and cancer.

Abstract: The complex cross-talk of intricate intercellular signaling networks between the tumor and stromal cells promotes cancer progression. Hypoxia is one of the most common conditions encountered within the tumor microenvironment that drives tumorigenesis. Most responses to hypoxia are elicited by a family of transcription factors called hypoxia-inducible factors (HIFs), which induce expression of a diverse set of genes that assist cells to adapt to hypoxic environments. Among the three HIF protein family members, the role of HIF-1 is well established in cancer progression. HIF-1 functions as a signaling hub to coordinate the activities of many transcription factors and signaling molecules that impact tumorigenesis. This mini review discusses the complex role of HIF-1 and its context-dependent partners under various cancer-promoting events including inflammation and generation of cancer stem cells, which are implicated in tumor metastasis and relapse. In addition, the review highlights the importance of therapeutic targeting of HIF-1 for cancer prevention.

Cellular plasticity and the neuroendocrine phenotype in prostate cancer

Abstract: The success of next-generation androgen receptor (AR) pathway inhibitors, such as abiraterone acetate and enzalutamide, in treating prostate cancer has been hampered by the emergence of drug resistance. This acquired drug resistance is driven, in part, by the ability of prostate cancer cells to change their phenotype to adopt AR-independent pathways for growth and survival. Around one-quarter of resistant prostate tumours comprise cells that have undergone cellular reprogramming to become AR-independent and to acquire a continuum of neuroendocrine characteristics. These highly aggressive and lethal tumours, termed neuroendocrine prostate cancer (NEPC), exhibit reactivation of developmental programmes that are associated with epithelial-mesenchymal plasticity and acquisition of stem-like cell properties. In the past few years, our understanding of the link between lineage plasticity and an emergent NEPC phenotype has considerably increased. This new knowledge can contribute to novel therapeutic modalities that are likely to improve the treatment and clinical management of aggressive prostate cancer.