Establishment of a predictive genetic model for estimating chemotherapy sensitivity of colorectal cancer with synchronous liver metastasis

Urinary dipeptidase 1 and trefoil factor 1 are promising biomarkers for early diagnosis of colorectal cancer

BACKGROUND

Currently utilized serum tumor markers and fecal immunochemical tests do not have sufficient diagnostic power for colorectal cancer (CRC) due to their low sensitivities. To establish non-invasive urinary protein biomarkers for early CRC diagnosis, we performed stepwise analyses employing urine samples from CRCs and healthy controls (HCs).

METHODS

Among 474 urine samples, 363 age- and sex-matched participants (188 HCs, 175 stage 0-III CRCs) were randomly divided into discovery (16 HCs, 16 CRCs), training (110 HCs, 110 CRCs), and validation (62 HCs, 49 CRCs) cohorts.

RESULTS

Of the 23 urinary protein candidates comprehensively identified from mass spectrometry in the discovery cohort, urinary levels of dipeptidase 1 (uDPEP1) and Trefoil factor1 (uTFF1) were the two most significant diagnostic biomarkers for CRC in both training and validation cohorts using enzyme-linked immunosorbent assays. A urinary biomarker panel comprising uDPEP1 and uTFF1 significantly distinguished CRCs from HCs, showing area under the curves of 0.825-0.956 for stage 0-III CRC and 0.792-0.852 for stage 0/I CRC. uDPEP1 and uTFF1 also significantly distinguished colorectal adenoma (CRA) patients from HCs, with uDPEP1 and uTFF1 increasing significantly in the order of HCs, CRA patients, and CRC patients. Moreover, expression levels of DPEP1 and TFF1 were also significantly higher in the serum and tumor tissues of CRC, compared to HCs and normal tissues, respectively.

CONCLUSIONS

This study established a promising and non-invasive urinary protein biomarker panel, which enables the early detection of CRC with high sensitivity.

A single-cell analysis of breast cancer cell lines to study tumour heterogeneity and drug response

Cancer cells within a tumour have heterogeneous phenotypes and exhibit dynamic plasticity. How to evaluate such heterogeneity and its impact on outcome and drug response is still unclear. Here, we transcriptionally profile 35,276 individual cells from 32 breast cancer cell lines to yield a single cell atlas. We find high degree of heterogeneity in the expression of biomarkers. We then train a deconvolution algorithm on the atlas to determine cell line composition from bulk gene expression profiles of tumour biopsies, thus enabling cell line-based patient stratification. Finally, we link results from large-scale in vitro drug screening in cell lines to the single cell data to computationally predict drug responses starting from single-cell profiles. We find that transcriptional heterogeneity enables cells with differential drug sensitivity to co-exist in the same population. Our work provides a framework to determine tumour heterogeneity in terms of cell line composition and drug response.

An aberrant DNA methylation signature for predicting the prognosis of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a common malignancy worldwide with a poor prognosis. DNA methylation is an epigenetic modification that plays a critical role in the etiology and pathogenesis of HNSCC. The current study aimed to develop a predictive methylation signature based on bioinformatics analysis to improve the prognosis and optimize therapeutic outcome in HNSCC. Clinical information and methylation sequencing data of patients with HNSCC were downloaded from The Cancer Genome Atlas database. The R package was used to identify differentially methylated genes (DMGs) between HNSCC and adjacent normal tissues. We identified 22 DMGs associated with 246 differentially methylated sites. Patients with HNSCC were classified into training and test groups. Cox regression analysis was used to build a risk score formula based on the five methylation sites (cg26428455, cg13754259, cg17421709, cg19229344, and cg11668749) in the training group. The Kaplan–Meier survival curves showed that the overall survival (OS) rates were significantly different between the high‐ and low‐risk groups sorted by the signature in the training group (median: 1.38 vs. 1.57 years, log‐rank test, p < 0.001). The predictive power was then validated in the test group (median: 1.34 vs. 1.75 years, log‐rank test, p < 0.001). The area under the receiver operating characteristic curve (area under the curve) based on the signature for predicting the 5‐year survival rates, was 0.7 in the training and 0.73 in test groups, respectively. The results of multivariate Cox regression analysis showed that the riskscore (RS) signature based on the five methylation sites was an independent prognostic tool for OS prediction in patients. In addition, a predictive nomogram model that incorporated the RS signature and patient clinical information was developed. The innovative methylation signature‐based model developed in our study represents a robust prognostic tool for guiding clinical therapy and predicting the OS in patients with HNSCC.

FXYD6 Regulates Chemosensitivity by Mediating the Expression of Na+/K+-ATPase α1 and Affecting Cell Autophagy and Apoptosis in Colorectal Cancer

PURPOSE

Chemoresistance is a challenge of improving chemotherapeutic efficacy and prolonging survival time for patients with colorectal cancer (CRC); it is the major cause of frequent recurrence, rapid metastasis, and poor prognosis for CRC patients. FXYD6 is a regulator of Na+/K+-ATPase which is depressed in chemoresistant CRC patients. However, the biological roles of FXYD6 on regulating chemoresistance in CRC are still unclear.

METHODS

GSE3964 and GSE69657 from GEO DataSets were used to analyze the relationship of genes and chemoresistance. The FXYD6 expression level was detected by western blotting and real-time PCR and also analyzed from TCGA DataSet. To investigate the functional role of FXYD6 and ATP-α1, FXYD6 and ATP-α1 functional cell models were constructed. Drug sensitivity and cell proliferation were performed by MTT assay. Autophagy and apoptosis were conducted by autophagy fluorescence analysis and flow cytometric analysis, respectively. Autophagy and apoptosis markers were tested by western blotting.

RESULTS

FXYD6 was downregulated in CRC resistant patients and irinotecan- (Iri-) resistant SW620 cells (SW620/Iri). FXYD6 silence inhibited cell apoptosis and enhanced prosurvival autophagy, whereas FXYD6 overexpression produced the opposite effect which alleviated the drug resistance to irinotecan and oxaliplatin of CRC cells. FXYD6 regulates chemosensitivity by mediating the expression of Na+/K+-ATPase α1 and affecting cell autophagy and apoptosis in colorectal cancer.

CONCLUSION

FXYD6 functions as a chemosensitivity regulator which may predict the curative effect of chemotherapy in colorectal cancer.

Development and validation of a HOXB8 gene-based prognostic model and nomogram for colorectal cancer patients

BACKGROUND

At present, colorectal cancer (CRC) is still associated with a high rate of recurrence and distant metastasis with a poor prognosis. HOXB8 gene is related to the tumorigenesis and development in CRC.

AIM

To explore the prognostic value of HOXB8 gene in CRC patients, and provide a novel insight into the monitoring of disease progression and cancer recurrence in patients with high-risk CRC.

METHODS

The mRNA sequencing data of HOXB8 in CRC patients was downloaded from The Cancer Genome Atlas database. Then, we analyzed the relationship between HOXB8 expression and clinicopathologic features in CRC, and performed survival analysis based on HOXB8 expression. Univariate and multivariate Cox regression analyese were performed for identifying prognostic factors for CRC, and then a nomogram was established and evaluated by concordance index, calibration curve, and decision curve analysis (DCA).

RESULTS

HOXB8 mRNA expression was significantly correlated with CRC tumor tissue (P < 0.001), right-side CRC (P < 0.001), T stage (P = 0.024), and M stage (P = 0.0074). Survival analysis showed that overexpression of HOXB8 was associated with a poor progression-free survival (PFS) in CRC patients (P = 0.0019). Univariate and multivariate COX analyses suggested that the expression level of HOXB8 [HR: 1.539 (1.066-2.221), P = 0.021] and TNM stage were independent prognostic factors for PFS of CRC patients. A nomogram was established to predict 3- and 5-year PFS of CRC patients based on four factors including HOXB8 expression and TNM stage. The concordance index was 0.735, suggesting good discrimination; the calibration curve and DCA showed that the nomogram had good predictive power and clinical practicability.

CONCLUSION

The expression of HOXB8 is significantly related to the prognosis of CRC patients, and it has appreciated predictive ability for disease progression and cancer recurrence in CRC patients. HOXB8 could act as a potential biomarker to identify high-risk CRC patients and become a novel therapeutic target and prognostic indicator for CRC.

Prognostic and clinic-pathological significances of HOXB8, ILK and FAT4 expression in colorectal cancer

INTRODUCTION

HOXB8 is a protein that was found to promote cancer proliferation and invasion. ILK is a protein kinase which has a role in carcinogenesis. FAT4 is a tumor homologue that has a role in EMT and autophagy regulation.

AIM OF THE STUDY

To identify expression of Human HOXB8, Integrin-linked kinase (ILK1) and FAT homolog 4 (FAT4) in colorectal cancer (CRC) correlating their expression with pathological, prognostic and clinical parameters of CRC.

MATERIAL AND METHODS

We assessed the expression of HOXB8, ILK and FAT4 in fifty CRC patients and ten samples from nearby non-neoplastic colonic mucosa using immunohistochemistry.

RESULTS

The expression of HOXB8 and ILK in CRC was positively associated with high tumor grade, advanced tumor stage, lymph node involvement (p < 0.001), occurrence of distant metastases (p = 0.003 and 0.024 respectively), higher incidence of tumor recurrence (p = 0.03, p < 0.001 respectively), worse survival rates (p = 0.038 and 0.003 respectively). The expression of FAT4 in CRC was correlated with lower grade, early stage of the tumor, absence of lymph node involvement (p < 0.001) and lack of distant metastases (p = 0.011). High FAT4 expression was associated with absence of tumor recurrence (p < 0.001) and favorable survival rates (p < 0.001 and 0.003).

CONCLUSIONS

High immunohistochemical expression of HOXB8 and ILK in addition to low immunohistochemical expression of FAT4 was associated with unfavorable prognostic and pathological parameters of CRC.

FXYD6 overexpression in HBV-related hepatocellular carcinoma with cirrhosis

Objective

The aim of this study was to investigate the expression of FXYD domain-containing ion transport regulator 6 (FXYD6) mRNA and protein in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) tissues with cirrhosis, the corresponding paracancerous tissues and the normal liver tissues, and to explore the clinical significance of FXYD6 expression in HBV-related HCC with cirrhosis.

Methods

The FXYD6 mRNA and protein were examined by semi-quantitative reverse transcription polymerase chain reaction and immunohistochemistry, respectively.

Results

The FXYD6 mRNA in HBV-related HCC tissues was significantly higher than that in the cirrhosis tissues or that in the normal liver tissues. The positive expression rate of FXYD6 protein was statistically higher in HBV-related HCC tissues than that in HBV-related cirrhosis or that in normal liver tissues. There was no significant correlation between the expression of FXYD6 protein and gender, age, histological differentiation, tumor diameter, tumor number, integrity of tumor capsule or not and alpha fetoprotein (AFP) concentration in serum, but the protein expression was associated with microvascular invasion, pathological stage, and early recurrence after operation within 1 year.

Conclusion

FXYD6 might be involved in hepatocyte carcinogenesis and tumor progression in HBV-related HCC with cirrhosis and indicated a poor prognosis.

Overexpressed CES2 has prognostic value in CRC and knockdown CES2 reverses L-OHP-resistance in CRC cells by inhibition of the PI3K signaling pathway

CES-2 (carboxylesterase-2) belongs to the carboxylesterase gene family, which plays crucial roles in lipid mobilization and chemosensitivity to irinotecan. However, its role in chemosensitivity to oxaliplatin (L-OHP) remains unclear. Herein, L-OHP-resistant cells (HCT-116L and RKOL) were established by increasing the concentration of L-OHP. The results showed that CES2 expression was upregulated in L-OHP-resistant tissues and cells lines (both P < 0.01). Low expression of CES2 correlated with a better survival, and the results were further confirmed in the R2 platform: a biologist friendly web-based genomics analysis and visualization application. Downregulation of CES2 suppressed cell proliferation, induced apoptosis and reversed L-OHP resistance by medicating the PI3K signaling pathway in L-OHP-resistant cells. However, both PI3K inhibitor (LY294002) and activator (IGF-1) could not medicate CES2 expression. These findings indicated that CES2 may be utilized as a novel biomarker and therapeutic target for L-OHP resistance in CRC treatment.

Knock-Down of HOXB8 Prohibits Proliferation and Migration of Colorectal Cancer Cells via Wnt/β-Catenin Signaling Pathway

Background

There has been no research on the mechanism of HOXB8 action on colorectal cancer so far. This study was designed to investigate the mechanism of HOXB8 regulating colorectal cancer cell proliferation and invasion in vivo and in vitro.

Material/Methods

HOXB8 shRNA, HOXB8 overexpression, and negative control vector were designed and stably transfected into HCT116 cells. MTT assays were performed to detect cell proliferation. Western blot was utilized to detect HOXB8 expression level in HCT116 stable cells. The invasive and migration abilities were detected by Transwell assay and wound-healing assay.

Results

HOXB8 knockdown inhibited cell proliferation. The invasiveness of HCT116 cells was significantly reduced following HOXB8 depletion compared with that in the shRNA control group, whereby the rates were reduced by 67% in HOXB8 knockdown group. The wound-healing rate of HOXB8 over-expression cells was significantly increased comparing with that of cells in the blank control group (P<0.05). HOXB8 knockdown promotes apoptosis of HCT116 cells. The expression of E-cadherin was restrained in the HOXB8 over-expression group and increased in the HOXB8 knockdown group.

Conclusions

Knock-down of HOXB8 prohibits the proliferation and migration of colorectal cancer cells via the Wnt/β-catenin signaling pathway and the downregulation of various factors, such as MMP2, c-Myc, CyclinD1,and vimentin. Our data suggested that HOXB8 has great potential to be developed as a novel therapeutic agent for the treatment of human colorectal cancer.

HOXB8 enhances the proliferation and metastasis of colorectal cancer cells by promoting EMT via STAT3 activation

Background

Previous studies have demonstrated that the expression of homeobox8 (HOXB8) is higher in colorectal cancer (CRC) tissues than in normal tissues; however, the precise role of HOXB8 in human CRC cells remains to be elucidated.

Methods

We generated lentiviral constructs to overexpress and silence HOXB8 in CRC cell lines, and examined their biological functions through MTT, wound healing, colony and transwell, expression of signal transducer and activator of transcription 3 (STAT3) and epithelial–mesenchymal transition (EMT) related factors through western-blot.

Results

HOXB8 knockdown inhibited cellular proliferation and invasion in vitro as well as carcinogenesis and metastasis in vivo. HOXB8 also induced EMT, which is characterized by the down-regulation of E-cadherin and the up-regulation of Vimentin, N-cadherin, Twist, Zeb1 and Zeb2. Moreover, HOXB8 activated STAT3, which is known to play an oncogenic role in diverse human malignancies.

Conclusions

Our results indicate that HOXB8 may be an independent prognostic factor in CRC. Therefore, deserved a deeper research.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0717-6) contains supplementary material, which is available to authorized users.

Identification of a Five-Gene Signature and Establishment of a Prognostic Nomogram to Predict Progression-Free Interval of Papillary Thyroid Carcinoma

Background: The incidence of papillary thyroid carcinoma (PTC) is high and increasing worldwide. Although prognosis is relatively good, it is important to select the minority of patients with poorer prognosis to avoid side effects associated with unnecessary over-treatment in low-risk patients; this requires accurate prognostic predictions. Materials and Methods: Six PTC expression datasets were obtained from the gene expression omnibus (GEO) database. Level 3 mRNA expression and clinicopathological data were obtained from The Cancer Genome Atlas Thyroid Cancer (TCGA-THCA) database. Through integrated analysis of these datasets, highly reliable differentially-expressed genes (DEGs) between tumor and normal tissue were identified and lasso Cox regression was applied to identify DEGs related to the progression-free interval (PFI) and to establish a prognostic gene signature. The performance of a five-gene signature was evaluated based on a Kaplan-Meier curve, receiver operating characteristic (ROC), and Harrell's concordance index (C-index). Multivariate Cox regression analysis was used to identify factors associated with PTC prognosis. Finally, a prognostic nomogram was established based on the TCGA-THCA dataset. Results: A novel five-gene signature was established to predict the PTC PFI, which included PLP2, LYVE1, FABP4, TGFBR3, and FXYD6, and the ROC curve and C-index showed good performance in both training and validation datasets. This could classify patients into high- and low-risk groups with distinct PFIs and differentiate PTC tumors from normal tissue. Univariate Cox regression revealed that this signature was an independent prognostic factor for PTC. The established nomogram, incorporating the prognostic gene signature and clinical parameters, was able to predict the PFI with high efficiency. The gene signature-based nomogram was superior to the American Thyroid Association (ATA) risk stratification to predict PTC PFI. Conclusions: Our study identified a five-gene signature and established a prognostic nomogram, which were reliable in predicting the PFI of PTC; this could be beneficial for individualized treatment and medical decision making.

Elevated tumor tissue protein expression levels of kallikrein-related peptidases KLK10 and KLK11 are associated with a better prognosis in advanced high-grade serous ovarian cancer patients

Several members of the KLK family have been proposed to modulate various tumor-relevant processes. Previously, we have shown that in advanced high-grade serous ovarian cancer tissue high KLK11 mRNA levels were significantly associated with prolonged overall and progression-free patients' survival. Furthermore, KLK11 mRNA expression positively correlated with KLK10 mRNA. In the present study, we examined the prognostic value for both KLK10 and KLK11 on the protein expression level by immunohistochemistry (IHC). A cohort encompassing 159 patient tumor samples afflicted with advanced high-grade (FIGO III/IV) serous ovarian cancer, present on tissue microarrays (TMA), was analyzed. For estimation of KLK10 and KLK11 immunoreactivity, an automated digital IHC image analysis algorithm was selected to quantify the antibody staining intensity in the tissues via an immunoreactive score (IRS). In line with the results obtained by mRNA analysis, KLK10 protein expression values were significantly and positively correlated with KLK11 protein expression values. In Kaplan-Meier analyses, both elevated KLK10, KLK11, and the combination of KLK10 and KLK11 protein levels were significantly linked with prolonged overall survival (OS). The addition of KLK10, KLK11 or the KLK10+KLK11 combination IRS to the base model in multivariate Cox analysis demonstrated that high KLK11 and KLK10+KLK11 protein expression levels, apart from clinical parameters, remained favorable independent predictive markers for OS. In conclusion, in the present study, we have validated the coordinate expression of KLK10 and KLK11 in advanced high-grade serous ovarian cancer. Furthermore, both increased KLK10 and KLK11 protein expression is associated with favorable prognosis in this major ovarian cancer subtype. The combined KLK10+KLK11 marker performed even stronger than KLK10 or KLK11 alone.

Knockdown of KLK11 reverses oxaliplatin resistance by inhibiting proliferation and activating apoptosis via suppressing the PI3K/AKT signal pathway in colorectal cancer cell

Introduction

Kallikrein 11 (KLK11) plays a crucial role in drug-resistance to oxaliplatin (L-OHP) in the treatment of metastatic colorectal cancer (mCRC). The study aimed to investigate the role of KLK11 in chemoresistance, and to clarify the mechanism underlying reverse of L-OHP resistance by knockdown of KLK11.

Materials and Methods

Resistance to oxaliplatin was induced in HCT-8 (HCT-8/L-OHP) colorectal adenocarcinoma cell lines by exposing cells to increasing concentrations of L-OHP. MTT, RT-qPCR, and Western blot were used to evaluate the resistance to L-OHP. We then knocked down KLK11 in HCT-8/L-OHP cells to explore the mechanism through which KLK11 reverses L-OHP resistance. The mRNA and protein expression of KLK11 in tissues from mCRC patients were detected by RT-qPCR and immunohistochemistry.

Results

The drug resistance index (RI) of HCT-8/L-OHP cell line to L-OHP, 5-Fluorouracil (5-FU), Irinotecan (CPT-11), Vincristine (VCR) and Cis-diamminedichloroplatinum (CDDP) were 10, 5.35, 3.23, 1.28, and 6.64, respectively. Increased expression of multi-drug resistant genes ABCC1, ABCB1, GSTP1 and ERCC1 were detected in HCT-8/L-OHP cell line. Moreover, the activated PI3K/AKT pathway was related to L-OHP-resistance. Knockdown of KLK11 in HCT-8/L-OHP cell reversed L-OHP-resistance by inhibiting cell growth and activating apoptosis via suppressing the PI3K/AKT signaling pathway. Moreover, high expression of KLK11 in chemoresistant-patients was associated with lymph node metastases and histopathology.

Conclusion

KLK11 was highly expressed in chemoresistant-patients and L-OHP-resistant cell lines. Moreover, L-OHP resistance was associated with activated PI3K/AKT signal pathway. Knockdown of KLK11 can reverse L-OHP resistance by blocking PI3K/AKT signaling pathway.

Genetics and epigenetics in small intestinal neuroendocrine tumours

Neuroendocrine tumour of the small intestine (SI-NET), formerly known as midgut carcinoid tumour, is the most common small intestinal malignancy. The incidence is rising, with recent reports of 0.67 per 100 000 in the USA and 1.12 per 100 000 in Sweden. SI-NETs often present a challenge in terms of diagnosis and treatment, as patients often have widespread disease and are beyond cure by surgery. Somatostatin analogues provide the mainstay of medical treatment to control hormonal excess and increase the time to progression. Despite overall favourable prognosis (5-year overall survival of 65%), there is a need to find markers to identify both patients with worse outcome and new targets for therapy. Loss on chromosome 18 has been reported in 60-90% of SI-NETs, but mutated genes on this chromosome have failed detection. Recently, a putative tumour suppressor role has been suggested for TCEB3C occurring at 18q21 (encoding elongin A3), which may undergo epigenetic repression. CDKN1B has recently been revealed as the only recurrently mutated gene in SI-NETs but, with a frequency as low as 8%, its role as a driver in SI-NET development may be questioned. Integrated genomewide analysis including exome and whole-genome sequencing, gene expression, DNA methylation and copy number analysis has identified three novel molecular subtypes of SI-NET with differing clinical outcome. DNA methylation analysis has demonstrated that SI-NETs have significant epigenetic dysregulation in 70-80% of tumours. In this review, we focus on understanding of the genetic, epigenetic and molecular events that lead to development and progression of SI-NETs.

Role of miR-196 and its target gene HoxB8 in the development and proliferation of human colorectal cancer and the impact of neoadjuvant chemotherapy with FOLFOX4 on their expression

The present study aimed to investigate the interaction between miR-196 and its target gene homeobox B8 (HoxB8) in colorectal cancer (CRC) cells, and the sensitivity of miR-196 and HoxB8 to fluorouracil, leucovorin and oxaliplatin (FOLFOX4) chemotherapy (1,200 mg/m² fluorouracil, 200 mg/m² leucovorin and 85 mg/m² oxaliplatin). In total, 80 tissue samples were collected in the present study. In total, 50 patients undergoing preoperative chemotherapy completed at least 3 cycles (2 weeks per cycle) of 85 mg/m² oxaliplatin (day 1) combined with a 2 h injection of 200 mg/m² leucovorin (days 1 and 2), a bolus injection of 400 mg/m² and 44 h continuous intravenous infusion of 1,200 mg/m² fluorouracil. Complete response and partial response were included in the chemotherapy sensitive group (25 patients), and stable disease and progressive disease were included in the chemotherapy resistant group (25 patients). In addition, 30 patients without preoperative chemotherapy were examined for mRNA and protein expression of miR-196 and HoxB8. The expression of the mRNA and protein of miR-196 and HoxB8 was analyzed in 30 CRC and normal mucosa tissue samples. In addition, the expression of the mRNA and protein of miR-196 and HoxB8 was measured in 50 tissue samples obtained from patients that had received FOLFOX4 neoadjuvant chemotherapy. The expression levels of miR-196 and HoxB8 mRNA in CRC tissues were significantly increased compared with the corresponding normal mucosa tissue (P<0.05). The miR-196 mRNA was significantly correlated with lymph node metastasis, tumor stage and distant metastasis (P<0.05). miR-196 was indicated to be negatively correlated with HoxB8 mRNA expression (r=-0.458; P<0.05). The relative amount of miR-196 in the chemotherapy-sensitive group of patients was 0.949±0.691, which was increased compared with the chemotherapy-resistant group (0.345±0.536; P<0.01). The relative level of HoxB8 mRNA in the chemotherapy-sensitive group was 0.490±0.372, which was decreaesd compared with the chemotherapy-resistant group (0.725±0.438; P<0.05). HoxB8 protein expression level in the chemotherapy-sensitive group was decreased compared with the chemotherapy-resistant group (Z=-2.396; P=0.017). Overall, miR-196 was correlated with metastasis and prognosis, and HoxB8 was highly expressed in CRC tissues. The difference in the gene expression of miR-196 and HoxB8 may be associated with the sensitivity to FOLFOX4 for CRC patients. In addition, the highly expressed miR-196 increased the sensitivity of CRC cells to chemotherapy with FOLFOX4 by inhibiting HoxB8.

The Genetic Landscape of Malignant Pleural Mesothelioma: Results from Massively Parallel Sequencing

Malignant pleural mesothelioma (MPM) is a rare yet aggressive tumor that is causally associated with-mostly professional-asbestos exposure. Given the long latency between exposure and disease, and because asbestos is still being used, MPM will remain a global health issue for decades to come. Notwithstanding the increasing incidence of MPM and the fact that patients with MPM face a poor prognosis, currently available treatment options are limited. To enable the development of novel targeted therapies, identification of the genetic alterations underlying MPM will be crucial. The first studies reporting on the genomic background of MPM identified recurrent somatic mutations in a number of tumor suppressor genes (i.e., cyclin-dependent kinase inhibitor 2A gene [CDKN2A], neurofibromin 2 (merlin) gene [NF2], and BRCA1 associated protein 1 gene [BAP1]). More recently, massively parallel sequencing strategies have been used and have provided a more genome-wide view on the genetic landscape of MPM. This review summarizes their results, describing alterations that cluster mainly in four pathways: the tumor protein p53/DNA repair, cell cycle, mitogen-activated protein kinase, and phosphoinisitide 3-kinase (PI3K)/AKT pathways. As these pathways are important during tumor development, they provide interesting candidates for targeting with novel drugs.

A plausible role for actin gamma smooth muscle 2 (ACTG2) in small intestinal neuroendocrine tumorigenesis

BACKGROUND

Small intestinal neuroendocrine tumors (SI-NETs) originate from the enterochromaffin cells in the ileum and jejunum. The knowledge about genetic and epigenetic abnormalities is limited. Low mRNA expression levels of actin gamma smooth muscle 2 (ACTG2) have been demonstrated in metastases relative to primary SI-NETs. ACTG2 and microRNA-145 (miR-145) are aberrantly expressed in other cancers and ACTG2 can be induced by miR-145. The aim of this study was to investigate the role of ACTG2 in small intestinal neuroendocrine tumorigenesis.

METHODS

Protein expression was analyzed in SI-NETs (n = 24) and in enterochromaffin cells by immunohistochemistry. The cell line CNDT2.5 was treated with the histone methyltransferase inhibitor 3-deazaneplanocin A (DZNep), the selective EZH2 inhibitor EPZ-6438, or 5-aza-2'-deoxycytidine, a DNA hypomethylating agent. Cells were transfected with ACTG2 expression plasmid or miR-145. Western blotting analysis, quantitative RT-PCR, colony formation- and viability assays were performed. miR-145 expression levels were measured in tumors.

RESULTS

Eight primary tumors and two lymph node metastases displayed variable levels of positive staining. Fourteen SI-NETs and normal enterochromaffin cells stained negatively. Overexpression of ACTG2 significantly inhibited CNDT2.5 cell growth. Treatment with DZNep or transfection with miR-145 induced ACTG2 expression (>10-fold), but no effects were detected after treatment with EPZ-6438 or 5-aza-2'-deoxycytidine. DZNep also induced miR-145 expression. SI-NETs expressed relatively low levels of miR-145, with reduced expression in metastases compared to primary tumors.

CONCLUSIONS

ACTG2 is expressed in a fraction of SI-NETs, can inhibit cell growth in vitro, and is positively regulated by miR-145. Theoretical therapeutic strategies based on these results are discussed.