Sequence and chromatin features guide DNA double-strand break resection initiation

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A new method of cryopreserving colorectal carcinoma cells for patient derived xenograft model generation

Patient derived xenograft (PDX) models provide an efficient way to study anti-tumor drug efficacy. In this respect, it is essential to study the optimal method needed to cryopreserve the starting cells obtained from tumor samples for PDX model generation. Cryopreservation of cells prior to xenografting is necessary for cross-verification of results obtained by xenografting and also for practical planning of experiments. In the present work, we studied the cryopreservation of colorectal carcinoma (CRC) cells isolated from patient tumor samples for generating their patient derived xenograft models. CRC therapeutics study is essential for early stage intervention and treatment of the disease. CRC cell lines do not ideally depict the molecular characteristics of patient CRC tumor samples. This necessitates the generation of CRC PDX models for drug discovery. We show that CRC cells isolated from patient tumor samples have comparable recovery, viability and growth with both conventional cryopreservation methods as well as Fibulas BioFlash Drive™. However, xenograft tumor formation was much more effective with Fibulas BioFlash Drive™ cryopreserved cells than with cells cryopreserved with conventional methods. Therefore, we put forward an effective way to cryopreserve primary cells obtained from patient tumor samples for PDX model generation in this study.     

Ascorbic acid analogue 6-Deoxy-6-[18F] fluoro-L-ascorbic acid as a tracer for identifying human colorectal cancer with SVCT2 overexpression

L-ascorbic acid (AA) was reported to have an anti-cancer effect over 40 years. In recent years, several ongoing clinical trials are exploring the safety and efficacy of intravenous high-dose AA for cancer treatment. The lack of appropriate imaging modality limits the identification of potentially suitable patients for AA treatment. This study focuses on identifying AA-sensitive tumor cells using molecular imaging. 6-Deoxy-6-[¹⁸F] fluoro-L-ascorbic Acid (¹⁸F-DFA), a structural analog of AA, was synthesized and labeled to visualize the metabolism of AA in vivo. Colorectal cancer (CRC) cell lines with high and low expression of sodium-dependent vitamin C transporters 2 (SVCT2) were used for a series of cellular uptake tests. PET imaging was performed on xenograft tumor-bearing mice. More AA uptake was observed in CRC cells with high SVCT2 expression than in cells with low SVCT2 expression. The substrate (unlabeled AA) can competitively inhibit the ¹⁸F-DFA tracer uptake by CRC cells. The biodistribution of ¹⁸F-DFA in mice showed high radioactivity was seen in organs such as adrenal glands, kidneys, and liver that were known to have high concentrations of AA. Both PET imaging and tissue distribution showed that cancer cells with high SVCT2 expression enhanced the accumulation of ¹⁸F-DFA in mice after tumor formation. Immunohistochemistry was used to verify the corresponding results. As a radiotracer, ¹⁸F-DFA can provide powerful imaging information to identify tumor with high affinity of AA, and SVCT2 can be a potential biomarker in this process.     

The proliferation of colorectal cancer cells is suppressed by silencing of EIF3H

Colorectal cancer is one of the most common causes of cancer-related deaths worldwide. Eukaryotic translation initiation factor 3, subunit H (EIF3H) is a subunit of EIF3, which is involved in mRNA recruitment and ribosomal complex disassembly and is known to be a driver of cell proliferation and survival in cancer. To investigate its function in colorectal cancer, the Oncomine database was used to evaluate the expression of EIF3H in human colorectal cancer and normal tissues. Then, we constructed a Lentivirus shorthair EIF3H vector (Lv-shEIF3H) to silence EIF3H expression in the colorectal cancer cell lines HCT116 and SW1116. We observed impaired cell growth and colony formation in these silenced cell lines. In addition, we showed that EIF3H knock-down led to cell apoptosis. In conclusion, EIF3H plays key roles in the apoptosis in colorectal cancer cells, which suggests EIF3H as a potential diagnostic biomarker in colorectal cancer.     

MicroRNA–mRNA interaction network using TSK-type recurrent neural fuzzy network

MicroRNAs are short non-coding RNAs that can regulate gene expression during various crucial cell processes such as differentiation, proliferation and apoptosis. Changes in expression profiles of miRNA play an important role in the development of many cancers, including CRC. Therefore, the identification of cancer related miRNAs and their target genes are important for cancer biology research. In this paper, we applied TSK-type recurrent neural fuzzy network (TRNFN) to infer miRNA–mRNA association network from paired miRNA, mRNA expression profiles of CRC patients. We demonstrated that the method we proposed achieved good performance in recovering known experimentally verified miRNA–mRNA associations. Moreover, our approach proved successful in identifying 17 validated cancer miRNAs which are directly involved in the CRC related pathways. Targeting such miRNAs may help not only to prevent the recurrence of disease but also to control the growth of advanced metastatic tumors. Our regulatory modules provide valuable insights into the pathogenesis of cancer.     

In situ quantification of aberrant p53 in colorectal neoplasia

Aberrant p53 protein accumulation was measured immunohistologically in 342 colorectal paraffin-embedded tissue sections from 115 patients (24 with adenocarcinoma, 59 with adenoma and 32 'hospital controls'). Subjective scoring was compared with quantitative cell imaging, including dichotomous (p53⁺/p53^?) status, ng p53^mut mg^?1 enterocyte protein, and tumour burden and patient body 'burden' of aberrant p53. A total of 62.5% cancer patients, 23.7% adenoma patients and 3.1% hospital controls were accorded p53⁺ status on the basis of p53 quantification. Quantitative p53⁺/p53^? assignment had a stronger inverse association with survival (χ²=6.17, p=0.013, Kaplan-Meier test) than subjective 'visual estimation' (χ²=0.57, p=0.449). There was a strong inverse relationship between the p53 'body burden' and the months of post-diagnosis survival (hazard ratio=1.42, p=0.0004, Cox proportional hazards). Absolute quantification for inactivated p53 permits objective and reproducible scoring, adjusts for intra-laboratory immunostaining 'batch effects', corrects for fixation artefacts, and standardizes for inter-laboratory differences in fixation, antibody selection and staining method. Clinically, in situ quantification of p53 will permit more accurate survival prognoses and will inform therapy selection and dose. Ultimately, accurate quantitative tissue/blood p53 correlations may provide a minimally invasive and systemic surrogate measure for these same clinical purposes.     

Mechanisms of helicase activated DNA end resection in bacteria

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