Anoxia/reoxygenation induces epithelial-mesenchymal transition in human colon cancer cell lines

Pt(iv) derivatives of cisplatin and oxaliplatin bearing an EMT-related TMEM16A/COX-2-selective dual inhibitor against colorectal cancer cells HCT116

Colorectal cancer represents the over-expression of TMEM16A and COX-2, offering a promising therapeutic strategy. Two Pt(iv) conjugates derived from Pt(ii) drug (cisplatin or oxaliplatin) and niflumic acid, complexes 1 and 2, were designed and prepared to exert the positive impact of multiple biological targets of DNA/TMEM16A/COX-2 against colorectal cancer. Complex 2 afforded higher cytotoxicity than 1 and the combination of an intermediate of oxidized oxaliplatin and NFA against cancer cells A549, HeLa, MCF-7, and HCT116. Especially for colorectal cancer cells HCT116, 2 was significantly more toxic (22-fold) and selective to cancer cells against normal HUVEC cells (4-fold) than first-line oxaliplatin. The outstanding anticancer activity of 2 is partly attributed to its dramatic increase in cellular uptake, DNA damage, and apoptosis. Mechanistic studies indicated that 2 inhibited HCT116 cell metastasis by triggering TMEM16A, COX-2, and their downstream signaling pathways, including EGFR, STAT3, E-cadherin and N-cadherin.

Prognostic value of baseline hemoglobin-to-red blood cell distribution width ratio in small cell lung cancer: A retrospective analysis

Background

This study aimed to investigate the prognostic value of baseline hemoglobin‐to‐red blood cell distribution width ratio (HRR) in patients with small cell lung cancer (SCLC).

Methods

We retrospectively analyzed the medical records of patients with newly diagnosed SCLC who had received first‐line chemotherapy at the Department of Pulmonary Oncology of the PLA 307 Hospital between January 2008 and October 2018. The optimal cutoff value of the continuous variables was determined using the X‐tile software. Univariate and multivariate analyses were conducted using Cox proportional hazard models. The Kaplan‐Meier method was used for survival analysis, with differences tested using the log‐rank test.

Results

A total of 146 patients were included. The cutoff value for HRR was determined as 0.985. Statistically significant differences were observed in sex, smoking history, stage, radiotherapy combination, neutrophil‐to‐lymphocyte ratio, platelet‐to‐lymphocyte ratio, hemoglobin, and red blood cell distribution width between the high and low HRR groups. The median overall survival (OS) was nine and 17.5 months in the low and high HRR groups, respectively (P < 0.001). The median progression‐free survival (PFS) was five and 8.5 months, respectively (P < 0.001). Univariate and multivariate analyses showed low HRR to be an independent predictor of a poor prognosis for OS (hazard ratio = 3.782; 95% confidence interval, 2.151–6.652; P < 0.001) and PFS (hazard ratio = 2.112; 95% confidence interval, 1.195–3.733; P = 0.01) in SCLC.

Conclusion

Low HRR was associated with poorer OS and PFS in patients with SCLC and can be a potentially valuable prognostic factor for these patients.

Key points

The prognostic value of the baseline hemoglobin‐to‐red blood cell distribution width ratio was evaluated in patients with small cell lung cancer.

In this population, this ratio was an independent predictor of overall survival and progression‐free survival. This ratio, an inexpensive and routine parameter, can be used as a prognostic factor in small cell lung cancer.

Differential anti-tumour effects of MTH1 inhibitors in patient-derived 3D colorectal cancer cultures

Reactive oxygen species (ROS) function as second messengers in signal transduction, but high ROS levels can also cause cell death. MTH1 dephosphorylates oxidized nucleotides, thereby preventing their incorporation into DNA and protecting tumour cells from oxidative DNA damage. Inhibitors of MTH1 (TH588 and (S)-crizotinib) were shown to reduce cancer cell viability. However, the MTH1-dependency of the anti-cancer effects of these drugs has recently been questioned. Here, we have assessed anti-tumour effects of TH588 and (S)-crizotinib in patient-derived 3D colorectal cancer cultures. Hypoxia and reoxygenation – conditions that increase intracellular ROS levels – increased sensitivity to (S)-crizotinib, but not to TH588. (S)-crizotinib reduced tyrosine phosphorylation of c-MET and ErbB3 whereas TH588 induced a mitotic cell cycle arrest, which was not affected by adding ROS-modulating compounds. Furthermore, we show that both compounds induced DNA damage that could not be prevented by adding the ROS inhibitor N-acetyl-L-cysteine. Moreover, adding ROS-modulating compounds did not alter the reduction in viability in response to TH588 and (S)-crizotinib. We conclude that TH588 and (S)-crizotinib have very clear and distinct anti-tumour effects in 3D colorectal cancer cultures, but that these effects most likely occur through distinct and ROS-independent mechanisms.

The anti-malarial atovaquone increases radiosensitivity by alleviating tumour hypoxia

Tumour hypoxia renders cancer cells resistant to cancer therapy, resulting in markedly worse clinical outcomes. To find clinical candidate compounds that reduce hypoxia in tumours, we conduct a high-throughput screen for oxygen consumption rate (OCR) reduction and identify a number of drugs with this property. For this study we focus on the anti-malarial, atovaquone. Atovaquone rapidly decreases the OCR by more than 80% in a wide range of cancer cell lines at pharmacological concentrations. In addition, atovaquone eradicates hypoxia in FaDu, HCT116 and H1299 spheroids. Similarly, it reduces hypoxia in FaDu and HCT116 xenografts in nude mice, and causes a significant tumour growth delay when combined with radiation. Atovaquone is a ubiquinone analogue, and decreases the OCR by inhibiting mitochondrial complex III. We are now undertaking clinical studies to assess whether atovaquone reduces tumour hypoxia in patients, thereby increasing the efficacy of radiotherapy.

Oxymatrine inhibits epithelial-mesenchymal transition through regulation of NF-κB signaling in colorectal cancer cells

Oxymatrine, a traditional Chinese herb extracted from Sophora flavescens Ait., displays strong anti-inflammatory and anticancer activities, but how oxymatrine exhibits anticarcinogenic effects in human colorectal cancer (CRC) remains uncertain. The present study aimed to elucidate the exact mechanism by which oxymatrine exhibits anticarcinogenic effects in CRC using the human colon cancer RKO cell line as the experimental model. CRC cells were treated with oxymatrine, and cell proliferation, migration and invasion were examined by colorimetric MTT, Transwell chamber and wound healing assays, respectively. In addition, epithelial-mesenchymal transition (EMT) markers and p65 were assessed by western blot analysis. Our study demonstrated that oxymatrine hindered the proliferation, migration and invasion of the CRC cells. Mechanistically, we found that oxymatrine modulated the expression of EMT markers including E-cadherin, Snail and N-cadherin, and reduced expression of p65 which is crucial to NF-κB activation. In conclusion, our results indicate that oxymatrine reduces the activation of the NF-κB signaling pathway and inhibits CRC invasion by modulating EMT.

Relationship between expression of NIBP and noncanonical NF-κB signaling: Clinical significance in colon carcinoma

AIM: To investigate the expression of NIK, IKKβ binding protein (NIBP), phosphorylated p100 (p-p100), p52, CD44, Vimentin and E-cadherin in colon carcinoma and to explore their clinical significance.

METHODS: Immunohistochemistry was used to detect the expression of NIBP, p-p100, p52, CD44, E-cadherin and Vimentin in 114 paraffin-embedded colon carcinoma tissues, 20 colon adenoma tissues and 50 normal colon mucosa tissues.

RESULTS: The positive expression of NIBP, p-p100, p52, CD44 and Vimentin in colon cancer tissues with metastasis was much higher than that in colon cancer tissues without metastasis, colon adenoma tissues and normal colon mucosa tissues, while the expression of E-cadherin showed a reverse trend (P < 0.05). The expression of NIBP, p-p100, p52, CD44, Vimentin and E-cadherin in colon cancer tissues was related with depth of invasion, TNM stage, lymph node metastasis and distant metastasis (P < 0.05). There were significant correlations between the expression of p-p100 and p52 or NIBP, and between the expression of CD44 and p52, E-cadherin, or Vimentin.

CONCLUSION: NIBP may regulate the epithelial-mesenchymal transition process by activating the noncanonical nuclear factor-κB (NF-κB) signal pathway and thus play an important role in the development, invasion and metastasis of colon cancer.

Hypoxia promotes stem cell phenotypes and poor prognosis through epigenetic regulation of DICER

MicroRNAs are small regulatory RNAs that post transcriptionally control gene expression. Reduced expression of DICER, the enzyme involved in microRNA processing, is frequently observed in cancer and is associated with poor clinical outcome in various malignancies. Yet, the underlying mechanisms are not well understood. Here we identify tumour hypoxia as a regulator of DICER expression in large cohorts of breast cancer patients. We show that DICER expression is suppressed by hypoxia through an epigenetic mechanism that involves inhibition of oxygen-dependent H3K27me3 demethylases KDM6A/B and results in silencing of the DICER promoter. Subsequently, reduced miRNA processing leads to derepression of the miR-200 target ZEB1, stimulates the epithelial to mesenchymal transition and ultimately results in the acquisition of stem cell phenotypes in human mammary epithelial cells. Our study uncovers a previously unknown relationship between oxygen-sensitive epigenetic regulators, miRNA biogenesis and tumour stem cell phenotypes that may underlie poor outcome in breast cancer.

Role of NF-κB in induction of epithelial-mesenchymal transition, migration and invasion of human colon cancer cells

AIM: To investigate the role of nuclear factor-kappa B (NF-κB) in the induction of epithelial-mesenchymal transition (EMT), migration and invasion of human colon cancer cell line HCT116.

METHODS: HCT116 cells were divided into three groups and treated with 20 ng/mL of tumor necrosis factor-α (TNF-α) (NF-κB activation group), 20 μmol/L of ammonium pyrrolidinedithiocarbamate (PDTC) (NF-κB suppression group), and equal volume of culture medium (control group), respectively. Four days later, cell morphological changes associated with EMT were observed under a phase contrast microscope, and the migration ability and invasiveness were assessed by Transwell chamber assays. The protein expression of p65, P-p65, E-cadherin and N-cadherin was analyzed by Western blot, and the mRNA expression of E-cadherin and N-cadherin was detected by quantitative real-time PCR.

RESULTS: TNF-α up-regulated the expression of P-p65 and N-cadherin, suppressed the expression of E-cadherin, and caused a complete EMT-phenotype, which manifested as the formation of large filopodia-like processes and spindle-cell shape. Also, TNF-α promoted cell invasion and migration. In contrast, PDTC down-regulated the expression of P-p65 and N-cadherin, up-regulated the expression of E-cadherin, inhibited the occurrence of typical EMT phenomenon, and suppressed cell invasion and migration. Compared with the control group, TNF-α group and PDTC group showed significantly different cell invasion (97.75 ± 3.77 vs 118.50 ± 1.95, 51.00 ± 1.83, P < 0.05 for both), cell migration (140.00 ± 4.32 vs 167.00 ± 6.36, 80.00 ± 2.53, P < 0.05 for both), and mRNA expression of N-cadherin (1.00 ± 0.00 vs 3.90 ± 0.47, 0.08 ± 0.02, P < 0.05 for both) and E-cadherin (1.00 ± 0.00 vs 0.26 ± 0.08, 6.03 ± 0.59, P < 0.05 for both).

CONCLUSION: NF-κB induces the occurrence of typical EMT phenomenon and promotes cell invasion and migration in human colon cancer cell line HCT116.

The inhibitory effect of heat treatment against epithelial-mesenchymal transition (EMT) in human pancreatic adenocarcinoma cell lines

Epithelial-mesenchymal transition (EMT) plays a crucial role in cancer metastasis. In this study, we evaluated the effect of heat treatment on tumor growth factor-β1 (TGF-β1)-induced EMT in pancreatic cancer cells and tried to ascertain the mechanism related to any observed effects. Human pancreatic cancer cell lines (BxPC-3, PANC-1 and MIAPaCa-2) were stimulated by TGF-β1, and evaluated for morphological changes using immunofluorescence and EMT-related factors (i.e., E-cadherin, Vimentin, Snail or ZEB-1) using RT-PCR. To examine the effect of heat on EMT, the cancer cells were heat-treated at 43°C for 1 h then stimulated with TGF-β1. We then evaluated whether or not heat treatment changed the expression of EMT-related factors and cell migration and also whether Smad activation was inhibited in TGF-β signaling. After being treated with TGF-β1, pancreatic cancer cells resulted in EMT and cell migration was enhanced. Heat treatment inhibited TGF-β1-induced changes in morphology, inhibited the expression of EMT-related factors, and attenuated TGF-β1-induced migration in pancreatic cancer cells. Additionally, we observed that heat treatment blocked TGF-β1-induced phosphorylation of Smad2 in PANC-1 cells. Our results suggest that heat treatment can suppress TGF-β1-induced EMT and opens the possibility of a new therapeutic use of hyperthermia as a potential treatment for cancer metastasis.

Epithelial-mesenchymal transition - activating transcription factors - multifunctional regulators in cancer

The process of epithelial to mesenchymal transition (EMT), first noted during embryogenesis, has also been reported in tumor formation and leads to the development of metastatic growth. It is a naturally occurring process that drives the transformation of adhesive, non-mobile epithelial like cells into mobile cells with a mesenchymal phenotype that have ability to migrate to distant anatomical sites. Activating complex network of embryonic signaling pathways, including Wnt, Notch, hedgehog and transforming growth factor-β pathways, lead to the upregulation of EMT activating transcription factors, crucial for normal tissue development and maintenance. However, deregulation of tightly regulated pathways affecting the process of EMT has been recently investigated in various human cancers. Given the critical role of EMT in metastatic tumor formation, better understanding of the mechanistic regulation provides new opportunities for the development of potential therapeutic targets of clinical importance.