Jingtai Zhi

Background: Cancer stem cells (CSCs) are highly tumorigenic, chemotherapy-resistant, tumor growth-sustaining, and are implicated in tumor recurrence. Previous studies have shown that lysine-specific histone demethylase 1A (KDM1A) is highly expressed in several human malignancies and CSCs. However, the role of KDM1A in CSCs and the therapeutic potential of KDM1A inhibitors for the treatment of the advanced thyroid cancer are poorly understood. Methods: Firstly, KDM1A was identified as an important epigenetic modifier that maintained the stemness of thyroid cancer through a mini histone methylation modifier screen and confirmed in thyroid cancer tissues and cell lines. RNA sequence was performed to discover the downstream genes of KDM1A. The underlying mechanisms were further investigated by ChIP, IP and dual luciferase reporter assays, gain and loss of function assays.

<h3>Objective</h3> The purposes of this study were to identify risk factors for cervical lymph node metastasis and to examine the association between <i>BRAF</i>^V600E status and clinical features in papillary thyroid microcarcinoma (PTMC). <h3>Methods</h3> A total of 1,587 patients with PTMC, treated in Tianjin Medical University Cancer Institute and Hospital from January 2011 to March 2013, underwent retrospective analysis. We reviewed and analyzed factors including clinical results, pathology records, ultrasound results, and <i>BRAF</i>^V600E status. <h3>Results</h3> Multivariate logistic regression analyses demonstrated that gender (male) [odds ratio (OR) = 1.845, <i>P</i> = 0.000], age (&lt; 45 years)(OR = 1.606, <i>P</i> = 0.000), tumor size (&gt; 6 mm) (OR = 2.137, <i>P</i> = 0.000), bilateralism (OR = 2.011, <i>P</i> = 0.000) and extrathyroidal extension (OR = 1.555, <i>P</i> = 0.001) served as independent predictors of central lymph node metastasis (CLNM). Moreover, CLNM (OR = 29.354, <i>P</i> = 0.000) served as an independent predictor of lateral lymph node metastasis (LLNM). Among patients with a solitary primary tumor, those with tumor location in the lower third of the thyroid lobe or the isthmus were more likely to experience CLNM (<i>P</i> &lt; 0.05). Univariate analyses indicated that CLNM, LLNM, extrathyroidal extension, and multifocality were not significantly associated with <i>BRAF</i>^V600E mutation. <h3>Conclusions</h3> The present study suggested that prophylactic neck dissection of the central compartment should be considered in patients with PTMC, particularly in men with tumor size greater than 6 mm, age less than 45 years, extrathyroidal extension, and tumor bilaterality. Among patients with PTMC, <i>BRAF</i>^V600E mutation is not significantly associated with prognostic factors. For a better understanding of surgical management of PTMC and the risk factors, we recommend multicenter research and long-term follow-up.

Background: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies, with no effective treatment currently available. The molecular mechanisms of ATC carcinogenesis remain poorly understood. The objective of this study was to investigate the mechanisms and functions of super-enhancer (SE)-driven oncogenic transcriptional addiction in the progression of ATC and identify new drug targets for ATC treatments. Methods: High-throughput chemical screening was performed to identify new drugs inhibiting ATC cell growth. Cell viability assay, colony formation analysis, cell-cycle analysis, and animal study were used to examine the effects of drug treatments on ATC progression. Chromatin immunoprecipitation sequencing was conducted to establish a SE landscape of ATC. Integrative analysis of RNA sequencing, chromatin immunoprecipitation sequencing, and CRISPR/Cas9-mediated gene editing was used to identify THZ1 target genes. Drug combination analysis was performed to assess drug synergy. Patient samples were analyzed to evaluate candidate biomarkers of prognosis in ATC. Results: THZ1, a covalent inhibitor of cyclin-dependent kinase 7 (CDK7), was identified as a potent anti-ATC compound by high-throughput chemical screening. ATC cells, but not papillary thyroid carcinoma cells, are exceptionally sensitive to CDK7 inhibition. An integrative analysis of both gene expression profiles and SE features revealed that the SE-mediated oncogenic transcriptional amplification mediates the vulnerability of ATC cells to THZ1 treatment. Combining this integrative analysis with functional assays led to the discovery of a number of novel cancer genes of ATC, including PPP1R15A , SMG9 , and KLF2 . Inhibition of PPP1R15A with Guanabenz or Sephin1 greatly suppresses ATC growth. Significantly, the expression level of PPP1R15A is correlated with CDK7 expression in ATC tissue samples. Elevated expression of PPP1R15A and CDK7 are both associated with poor clinical prognosis in ATC patients. Importantly, CDK7 or PPP1R15A inhibition sensitizes ATC cells to conventional chemotherapy. Conclusions: Taken together, these findings demonstrate transcriptional addiction in ATC pathobiology and identify CDK7 and PPP1R15A as potential biomarkers and therapeutic targets for ATC.

Background: Patients with metastatic radioiodine-refractory papillary thyroid carcinoma (PTC) have limited options for treatment and a poor prognosis. There is an urgent need to develop new drugs for clinical application. Apatinib is a novel small molecule tyrosine kinase inhibitor that is highly selective for vascular endothelial growth factor receptor-2 (VEGFR2) and exhibits antitumor effects in a variety of solid tumors. It has shown safety and efficacy in radioiodine-refractory differentiated thyroid cancer, but the mechanism underlying the antitumor effect is unclear. In this report, we explored the effects of apatinib on PTC in vitro and in vivo. Methods: VEGFR2 expression level was evaluated by IHC, qPCR and WB. The effect of apatinib was assessed in terms of cell viability, colony formation and transwell assay in vitro, and tumor growth rate in vivo. Protein levels of signaling pathway were determined by western blot. Autophagy level was assessed by western blot, IF and transmission electron microscopy. Results: We found that high VEGFR2 expression is associated with tumor size, T stage and lymph node metastasis in patients with PTC and that apatinib inhibits PTC cell growth, promotes apoptosis, and induces cell cycle arrest through the PI3K/Akt/mTOR signaling pathway. Moreover, apatinib induces autophagy, and pharmacological inhibition of autophagy or small interfering RNA targeting autophagy-associated gene 5 (ATG5) can further increase PTC cell apoptosis. Conclusion: Our data suggest that apatinib can induce apoptosis and autophagy via the PI3K/Akt/mTOR signaling pathway in the treatment of PTC, and autophagy is a potential novel target for future therapy in resistant PTC.

CONTEXT: Multiple mechanisms play roles in restricting the ability of T-cells to recognize and eliminate tumor cells. OBJECTIVE: To identify immune escape mechanisms involved in papillary thyroid carcinoma (PTC) to optimize immunotherapy. SETTING AND DESIGN: iTRAQ analysis was conducted to identify proteins differentially expressed in PTC samples with or without BRAFV600E mutation. Molecular mechanisms regulating tumor cell evasion were investigated by in vitro modulations of BRAF/MAPK and related pathways. The pathological significance of identified tumor-specific major histocompatibility complex class II (tsMHCII) molecules in mediating tumor cell immune escape and targeted immune therapy was further evaluated in a transgenic mouse model of spontaneous thyroid cancer. RESULTS: Proteomic analysis showed that tsMHCII level was significantly lower in BRAFV600E-associated PTCs and negatively correlated with BRAF mutation status. Constitutive activation of BRAF decreased tsMHCII surface expression on tumor cells, which inhibited activation of CD4+ T-cells and led to immune escape. Pathway analysis indicated that the transforming growth factor (TGF)-β1/SMAD3-mediated repression of tsMHCII, which could be reversed by BRAF inhibition (BRAFi). Targeting this pathway with a combined therapy of BRAF inhibitor PLX4032 and anti-PD-1 antibody efficiently blocked tumor growth by increasing CD4+ T-cell infiltration in a transgenic PTC mouse model. CONCLUSIONS: Our results suggest that BRAFV600E mutation in PTC impairs the expression of tsMHCII through the TGF-β1/SMAD3 pathway to enhance immune escape. Combined treatment with PLX4032 and anti-PD-1 antibody promotes recognition and elimination of PTC by the immune system in a pre-clinical mouse model, and therefore offers an effective therapeutic strategy for patients with advanced PTC.