Functional analysis of the short splicing variant encoded by CHI3L1/YKL-40 in glioblastoma

The glycoprotein YKL-40 has been well studied as a serum biomarker of prognosis and disease status in glioblastoma. YKL-40 is a chitinase-like protein with defective chitinase activity that plays an important role in promoting cell proliferation, migration, and metastasis in glioblastoma multiforme (GBM). The short variant (SV) of YKL-40, generated by an alternative splicing event that splices out exon 8, was reported in the early developing human musculoskeletal system, although its role in GBM is still unknown. Our results showed that individual glioblastoma cell lines displayed increased expression of the short variant of YKL-40 after low serum treatment. In addition, unlike the full-length (FL) version, which was localized to all cell compartments, the short isoform could not be secreted and was localized only to the cytoplasm. Functionally, FL YKL-40 promoted cell proliferation and migration, whereas SV YKL-40 suppressed them. Transcriptome analysis revealed that these opposing roles of the two isoforms may be modulated by differentially regulating several oncogenic-related pathways, including p53, the G2/M checkpoint, and MYC-related signaling. This study may provide new ideas for the development of targeted anti-YKL-40 therapy in GBM treatment.

Endothelial nitric oxide synthase (eNOS)-NO signaling axis functions to promote the growth of prostate cancer stem-like cells

BACKGROUND

Accumulating evidence supports that prostate cancer stem-like cells (PCSCs) play significant roles in therapy resistance and metastasis of prostate cancer. Many studies also show that nitric oxide (NO) synthesized by NO synthases can function to promote tumor progression. However, the exact roles of NOSs and NO signaling in the growth regulation of PCSCs and castration-resistant prostate cancer (CRPC) are still not fully understood.

METHODS

The regulatory functions of NOS-NO signaling were evaluated in prostate cancer cells, especially in PCSCs enriched by 3D spheroid culture and CD133/CD44 cell sorting. The molecular mechanisms of NOS-NO signaling in PCSCs growth regulation and tumor metastasis were investigated in PCSCs and mice orthotopic prostate tumor model.

RESULTS

Endothelial NOS (eNOS) exhibited a significant upregulation in high-grade prostate cancer and metastatic CRPC. Xenograft models of CRPC exhibited notable increased eNOS expression and higher intracellular NO levels. PCSCs isolated from various models displayed significant enhanced eNOS-NO signaling. Functional analyses demonstrated that increased eNOS expression could promote in vivo tumorigenicity and metastatic potential of prostate cancer cells. Characterization of eNOS-NO involved downstream pathway which confirmed that enhanced eNOS signaling could promote the growth of PCSCs and antiandrogen-resistant prostate cancer cells via an activated downstream NO-sGC-cGMP-PKG effector signaling pathway. Interestingly, eNOS expression could be co-targeted by nuclear receptor ERRα and transcription factor ERG in prostate cancer cells and PCSCs.

CONCLUSIONS

Enhanced eNOS-NO signaling could function to promote the growth of PCSCs and also the development of metastatic CRPC. Besides eNOS-NO as potential targets, targeting its upstream regulators (ERRα and ERG) of eNOS-NO signaling could also be the therapeutic strategy for the management of advanced prostate cancer, particularly the aggressive cancer carrying with the TMPRSS2:ERG fusion gene.

The genetic landscapes of inflammation-driven gastrointestinal tract cancers

Gastrointestinal (GI) tract cancers account for a significant proportion of human malignancies. While classical multistep carcinogenesis is characterized by the stochastic accumulation of genetic mutations, additional extrinsic factors can also contribute to tumor promotion. Inflammation plays a critical role in cancers of the GI tract, for which the two major etiological factors are tissue injuries and altered microbiota. Together with infiltrating immune cells, all of these components generate a dynamic tumor microenvironment that inevitably induces malignant progression and metastatic growth. Crosstalk between tumor and immune cells is mediated by a multitude of pro- and anti- inflammatory cytokines. Their biological actions are propagated in both tumor and immune cells through an intricate network of intracellular signaling pathways that ultimately modulate essential cellular functions such as tumorigenic properties and lineage specification. Using the vast amount of information stored in the database on genetic changes associated with human cancers that has been collected over the past decades, this book chapter will first profile the genomic and transcriptomic landscapes of some of the major GI tract cancers. Critical driver genes and pro-inflammatory cytokines will be discussed in detail. The mechanisms by which genetic mutations in cancer cells can provoke inflammation and vice versa will be explored. The way in which the symbiotic relationship between cancer cells and chronic inflammation can modulate tumor cell behavior will be examined. We will present some of the most recent advancements in the targeting of inflammation for the treatment of GI tract cancers.