Bo Wen Lin

Overexpression of Pyruvate Dehydrogenase Kinase 3 Increases Drug Resistance and Early Recurrence in Colon Cancer

The switch of cellular metabolism from mitochondrial respiration to glycolysis is the hallmark of cancer cells and is associated with tumor malignancy. Pyruvate dehydrogenase kinase-1 (PDK1) and PDK3 participate in the metabolic switch of cancer cells; however, the medical significance of PDK1 and PDK3 in cancer progression is not known. Here, we assessed the expression profiles of PDK1 and PDK3 in colorectal cancer. Western blot analysis (n = 74) demonstrated that PDK3 was markedly increased in colon cancer compared to that in adjacent normal tissues, whereas PDK1 was decreased in cancer cells. In addition, PDK3 expression was positively correlated with that of hypoxia inducible factor-1α (HIF-1α) in cancer cells. Further analysis using immunohistochemical staining revealed that PDK3 levels were positively associated with severity of cancer and negatively associated with disease-free survival. In vitro studies using several colon cancer cell lines showed that PDK3 expression was controlled by HIF-1α and contributed to hypoxia-induced increased drug resistance, perhaps explaining why patients with PDK3 overexpression have a greater incidence of treatment failure. Taken together, our findings suggest that PDK3 plays an important role in the metabolic switch and drug resistance of colon cancer and is potentially a novel target for cancer therapy.

Regulation of CD151 by Hypoxia Controls Cell Adhesion and Metastasis in Colorectal Cancer

Purpose: The first step of metastasis is the detachment of cancer cells from the surrounding matrix and neighboring cells; however, how cancer cells accomplish this process remains unclear. Thus, we aimed to investigate the underlying mechanism that controls the early event of metastasis. Experimental Design: One hundred and thirty-seven paired colorectal carcinoma and normal colon tissues were examined by immunohistochemical staining and Western blot for the expression of CD151, a member of the tetraspanin family that plays important roles in cell adhesion and motility. The effect of CD151 on cancer cell adhesion was investigated under normoxia and hypoxia conditions. Results: The level of CD151 was down-regulated in colon cancer compared with the paired normal counterparts. Expression of CD151 was negatively regulated by hypoxia inducible factor-1–dependent hypoxic stress. Suppression of CD151 by hypoxia caused the detachment of cancer cells from the surrounding matrix and neighboring cells whereas restoration of CD151 expression during reoxygenation facilitated the adhesion capacity. Clinical examination further showed that metastasized cancer cells expressed a greater level of CD151 compared with that of primary tumor. Conclusion: Regulation of CD151 by oxygen tension may play an important role in cancer metastasis by regulating the detachment from the primary site and homing in the secondary site.

Aberrantly expressed AURKC enhances the transformation and tumourigenicity of epithelial cells

Over‐expression of AURKC has been detected in human colorectal cancers, thyroid carcinoma and several cancer cell lines. However, the regulation and clinical implications of over‐expressed AURKC in cancer cells are unclear. Here we show that elevated AURKC increases the proliferation, transformation and migration of cancer cells. Importantly, the kinase activity of AURKC is required for these tumour‐associated properties. Analysis of human cancer specimens shows that the expression of AURKC is increased in cervical cancer, and is highly correlated with staging in colorectal cancer. Over‐expressed AURKC‐GFP localizes to the centromeric regions of mitotic chromosomes and results in a decreased level of AURKB, a key regulator of spindle checkpoint. Expression of AURKC is down‐regulated by PLZF, a transcriptional repressor, through recruitment to its promoter region. The expression levels of PLZF and AURKC mRNA display opposite patterns in human cervical and colorectal cancers. Taken together, our results provide important insights into human cancers with AURKC expression, which may serve as a potential target for cancer therapy in the future. Copyright

Translational up-regulation of Aurora-A in EGFR-overexpressed cancer.

Abnormal expression of Aurora‐A and epidermal growth factor receptor (EGFR) is observed in different kinds of cancer and associated with poor prognosis in cancer patients. However, the relationship between Aurora‐A and EGFR in tumour development was not clear. In previous reports, we found that EGFR translocates to nucleus to activate Aurora‐A expression after EGF treatment in EGFR‐overexpressed cells. However, we also observed that not all the EGFR‐overexpressed cells have the nuclear EGFR pathway to mediate the Aurora‐A expression. In this study, we demonstrated that EGF signalling increased the Aurora‐A protein expression in EGFR‐overexpressed colorectal cancer cell lines via increasing the translational efficiency. In addition, the overexpression of EGFR was also associated with higher expression of Aurora‐A in clinical colorectal samples. Activation of the PI3K/Akt/mTOR and MEK/ERK pathways mediated the effect of EGF‐induced translational up‐regulation. Besides, only the splicing variants containing exon 2 of Aurora‐A mRNA showed increased interaction with the translational complex to synthesize Aurora‐A protein under EGF stimulus. Besides, the exon 2 containing splicing variants were the major Aurora‐A splicing forms expressed in human colorectal cancers. Taken together, our results propose a novel regulatory mechanism for the abnormal expression of Aurora‐A in EGFR‐overexpressed cancers, and highlight the importance of alternative 5′‐UTR splicing variants in regulating Aurora‐A expression. Furthermore, the specific expression of exon 2 containing splicing variants in cancer tissues may serve as a potential target for cancer therapy in the future.

A retrospective study of pulmonary infarction in patients with systemic lupus erythematosus from southern Taiwan

Since large-scale reports of pulmonary infarction in systemic lupus erythematosus (SLE) are limited, a retrospective study was performed for this manifestation in 773 hospitalized patients in southern Taiwan from 1999 to 2009. Pulmonary infarction was defined as the presence of pulmonary embolism, persistent pulmonary infiltrates, and characteristic clinical symptoms. Demographic, clinical, laboratory, and radiological images data were analyzed. There were 12 patients with pulmonary embolism and 9 of them had antiphospholipid syndrome (APS). Six patients (19 to 53 years, average 38.2 ± 12.6) with 9 episodes of lung infarction were identified. All cases were APS and four episodes had coincidental venous thromboembolism. There were four episodes of bilateral infarction and seven episodes of larger central pulmonary artery embolism. Heparin therapy was routinely prescribed and thrombolytic agents were added in two episodes. Successful recovery was noted in all patients. In conclusion, there was a 0.8% incidence of pulmonary infarction in patients with SLE, all with the risk factor of APS. Differentiation between pulmonary infarction and pneumonia in lupus patients should be made; they have similar chest radiography with lung consolidation but require a different clinical approach in management. Although this report is a retrospective study with relatively small numbers of lupus patients with lung infarcts, our observation might provide beneficial information on the clinical features and radiological presentations during the disease evolution of pulmonary infarction in SLE with APS.

Hypoxia-Induced Downregulation of DUSP-2 Phosphatase Drives Colon Cancer Stemness

Cancer stem-like cells (CSC) evolve to overcome the pressures of reduced oxygen, nutrients or chemically induced cell death, but the mechanisms driving this evolution are incompletely understood. Here, we report that hypoxia-mediated downregulation of the dual specificity phosphatase 2 (DUSP2) is critical for the accumulation of CSC in colorectal cancer. Reduced expression of DUSP2 led to overproduction of COX-2-derived prostaglandin E2, which promoted cancer stemness via the EP2/EP4 signaling pathways. Genetic and pharmacological inhibition of PGE2 biosynthesis or signal transduction ameliorated loss-of-DUSP2-induced tumor growth and cancer stemness. Genome-wide profile analysis revealed that genes regulated by DUSP2 were similar to those controlled by histone deacetylase. Indeed, treatment with novel histone deacetylase inhibitors abolished hypoxia-induced DUSP2 downregulation, COX-2 overexpression, cancer stemness, tumor growth, and drug resistance. Our findings illuminate mechanisms of cancer stemness and suggest new cancer therapy regimens. Cancer Res; 77(16); 4305-16. ©2017 AACR.

Targeting TYRO3 inhibits epithelial-mesenchymal transition and increases drug sensitivity in colon cancer.

Colon cancer is the third leading cause of death from cancer worldwide with less than 10% survival rate at the late stage. Although mutations of certain genes have been implicated in familial colon cancer development, the etiology of the majority of colon cancer remains unknown. Herein, we identified TYRO3 as a potential oncogene. Immunohistochemical staining results demonstrated that levels of TYRO3 were markedly elevated in polyps and colon cancer cells and were negatively correlated with prognosis. Overexpression of TYRO3 enhanced cell motility, invasion, anchorage-independent growth and metastatic ability, while knockdown of TYRO3 impaired all these processes. Results from meta-analysis showed that TYRO3 was associated with epithelial–mesenchymal transition (EMT) signatures. Gain-of-function and loss-of-function experiments demonstrated that expression of SNAI1, the master regulator of EMT, was regulated by TYRO3 and played a major role in mediating TYRO3-induced EMT processes. The murine model also demonstrated that Tyro3 and Snai1 were upregulated in the early stage of colon cancer development. To provide a proof-of-concept that TYRO3 is a druggable target in colon cancer therapy, we raised anti-TYRO3 human antibodies and showed that treatment with the human antibody abolished TYRO3-induced EMT process. More importantly, administration of this anti-TYRO3 antibody increased drug sensitivity in primary cultured colon cancer cells and xenografted mouse tumors. These findings demonstrate that TYRO3 is a novel oncogene and a druggable target in colon cancer.

STK31 is a cell-cycle regulated protein that contributes to the tumorigenicity of epithelial cancer cells.

Serine/threonine kinase 31 (STK31) is one of the novel cancer/testis antigens for which its biological functions remain largely unclear. Here, we demonstrate that STK31 is overexpressed in many human colorectal cancer cell lines and tissues. STK31 co-localizes with pericentrin in the centrosomal region throughout all phases of the cell cycle. Interestingly, when cells undergo mitosis, STK31 also localizes to the centromeres, central spindle, and midbody. This localization behavior is similar to that of chromosomal passenger proteins, which are known to be the important players of the spindle assembly checkpoint. The expression of STK31 is cell cycle-dependent through the regulation of a putative D-box near its C-terminal region. Ectopically-expressed STK31-GFP increases cell migration and invasive ability without altering the proliferation rate of cancer cells, whereas the knockdown expression of endogenous STK31 by lentivirus-derived shRNA results in microtubule assembly defects that prolong the duration of mitosis and lead to apoptosis. Taken together, our results suggest that the aberrant expression of STK31 contributes to tumorigenicity in somatic cancer cells. STK31 might therefore act as a potential therapeutic target in human somatic cancers.

Routine defunctioning stoma after chemoradiation and total mesorectal excision: a single-surgeon experience.

AIM To investigate the 10-year results of treating low rectal cancer by a single surgeon in one institution. METHODS From Oct 1998 to Feb 2009, we prospectively followed a total of 62 patients with cT2-4 low rectal cancer with lower tumor margins measuring at 3 to 6 cm above the anal verge. All patients received neoadjuvant chemoradiation (CRT) for 6 wk. Among them, 85% of the patients received 225 mg/m(2)/d 5-fluorouracil using a portable infusion pump. The whole pelvis received a total dose of 45 Gy of irradiation in 25 fractions over 5 wk. The interval from CRT completion to surgical intervention was planned to be approximately 6-8 wk. Total mesorectal excision (TME) and routine defunctioning stoma construction were performed by one surgeon. The distal resection margin, circumferential resection margin, tumor regression grade (TRG) and other parameters were recorded. We used TRG to evaluate the tumor response after neoadjuvant CRT. We evaluated anal function outcomes using the Memorial Sloan-Kettering Cancer Center anal function scores after closure of the defunctioning stoma. RESULTS The median distance from the lower margin of rectal cancer to the anal verge was 5 cm: 6 cm in 9 patients, 5 cm in 32 patients, 4 cm in 10 patients, and 3 cm in 11 patients. Before receiving neoadjuvant CRT, 45 patients (72.6%) had a cT3-4 tumor, and 21 (33.9%) patients had a cN1-2 lymph node status. After CRT, 30 patients (48.4%) had a greater than 50% clinical reduction in tumor size. The final pathology reports revealed that 33 patients (53.2%) had a ypT3-4 tumor and 12 (19.4%) patients had ypN1-2 lymph node involvement. All patients completed the entire course of neoadjuvant CRT. Most patients developed only Grade 1-2 toxicities during CRT. Thirteen patients (21%) achieved a pathologic complete response. Few post-operative complications occurred. Nearly 90% of the defunctioning stomas were closed within 6 mo. The local recurrence rate was 3.2%. Pathologic lymph node involvement was the only prognostic factor predicting disease recurrence (36.5% vs 76.5%, P = 0.006). Nearly 90% of patients recovered sphincter function within 2 year after closure of the defunctioning stoma. CONCLUSION Neoadjuvant CRT followed by TME, combined with routine defunctioning stoma construction and high-volume surgeon experience, can provide excellent surgical quality and good local disease control.

Translational upregulation of Aurora-A by hnRNP Q1 contributes to cell proliferation and tumorigenesis in colorectal cancer

By using RNA-immunoprecipitation assay following next-generation sequencing, a group of cell cycle-related genes targeted by hnRNP Q1 were identified, including Aurora-A kinase. Overexpressed hnRNP Q1 can upregulate Aurora-A protein, but not alter the mRNA level, through enhancing the translational efficiency of Aurora-A mRNA, either in a cap-dependent or -independent manner, by interacting with the 5′-UTR of Aurora-A mRNA through its RNA-binding domains (RBDs) 2 and 3. By ribosomal profiling assay further confirmed the translational regulation of Aurora-A mRNA by hnRNP Q1. Overexpression of hnRNP Q1 promotes cell proliferation and tumor growth. HnRNP Q1/ΔRBD23-truncated mutant, which loses the binding ability and translational regulation of Aurora-A mRNA, has no effect on promoting tumor growth. The expression level of hnRNP Q1 is positively correlated with Aurora-A in colorectal cancer. Taken together, our data indicate that hnRNP Q1 is a novel trans-acting factor that binds to Aurora-A mRNA 5′-UTRs and regulates its translation, which increases cell proliferation and contributes to tumorigenesis in colorectal cancer.