Tsutomu Kawaguchi

Overexpression of suppressive microRNAs, miR-30a and miR-200c are associated with improved survival of breast cancer patients

Some microRNAs (miRNAs) are known to suppress breast cancer. However, whether the expressions of these tumor suppressive miRNAs translate to patient survival were not investigated in large cohort. Nine miRNAs (miR-30a, miR-30c, miR-31, miR-126, miR-140, miR-146b, miR-200c, miR-206, and miR-335) known to be tumor suppressive miRNAs in breast cancer were investigated in Genomic Data Common data portal miRNA-Seq dataset and The Cancer Genome Atlas (TCGA) (n = 1052). Of the 9 miRNAs, miR-30a, miR-30c, miR-126, miR-140, miR-206, and miR-335 were found to have significantly lower expression in breast cancer tissues compared to paired normal breast tissue. High expression of miR-30a or miR-200c was associated with significantly better overall survival (OS). Gene Set Enrichment Analysis (GSEA) demonstrated that low expression levels of miR-30a had the tendency to associate with gene enrichment of EMT, while miR-200c did not, in TCGA cohort, and our findings support the need of validation using large cohort to use miRNA as prognostic biomarker for patients with breast cancer.

Current Update of Patient-Derived Xenograft Model for Translational Breast Cancer Research

Despite recent advances in the treatment of patients with breast cancer (BrCa), BrCa remains the third leading cause of cancer death for women in the US due to intrinsic or acquired resistance to therapy. Continued understanding of gene expression profiling and genomic sequencing has clarified underlying intratumoral molecular heterogeneity. Recently, the patient-derived xenograft (PDX) models have emerged as a novel tool to address the issues of BrCa genomics and tumor heterogeneity, and to critically transform translational BrCa research in the preclinical setting. PDX models are generated by xenografting cancer tissue fragments obtained from patients to immune deficient mice, and can be passaged into next generations of mice. Generally, in contrast to conventional xenograft using cancer cell lines, PDXs are biologically more stable and recapitulate the individual tumor morphology, gene expression, and drug susceptibility of each patient. PDX may better model the original patient’s tumor by retaining tumor heterogeneity, gene expression, and similar response to treatment. PDX models are thus thought to be more translationally relevant, especially as a drug development tool, because PDXs can capture the genetic character and heterogeneity that exists within a single patient’s tumor and across a population of patients’ tumors. PDX models also hold enormous potential for identifying predictive markers for therapeutic response. It has been repeatedly shown that PDX models demonstrate similar levels of activity as compared to the clinical response to therapeutic interventions. Therefore, this enables identification of therapeutic interventions that can most likely benefit a patient. This allows us to address the issues of BrCa genomics and tumor heterogeneity using PDXs in “pre-clinical” trials. Herein, we reviewed recent scientific development and future perspectives using PDX models in BrCa.

Abstract 1049: Orthotopic implantation of aggressive breast cancer achieves better engraftment and larger tumor in patient-derived xenograft models

Background: Breast cancer patient-derived xenograft (PDX) has come into the limelight to address the issue of intratumoral heterogeneity in preclinical studies; however, there are still some unsolved problems regarding its practical usage in translational research. There are no systematic studies that clarify the advantage of orthotopic implantation of the tumor as opposed to ectopic, or of the type of source tumor. Thus, we investigated the difference of tumor growth caused by these variables among breast cancer PDX model mice. Methods: We xenografted 10 patient breast cancer tumors into NSG mice. 2 tumors were derived from brain metastasis (B-met), whereas the others were from primary. 3 tumors were ER(+) HER2(-) and 7 tumors were triple negative (TN). Both of b-met tumors are ER(+) HER2(-). Using 2-3 mice per each patient sample, about 1mm3 tumor fragments were implanted surgically into four subcutaneous (SQ) sites ectopically and four sites (bilateral 2nd and 4th mammary fat pad) orthotopically (Orth). Tumors were passaged to another 2-4 mice as the next generation when the largest tumor grew to 1.5cm in diameter. Tumor “take” was defined as tumorigenesis of palpable tumor after implantation regardless of time it took. Results: PDX tumors were established in 7 out of 10 patient tumors. Histologic grade 3 tumors have significantly higher take rate than grade 2 tumors in 1st generation (3.4% [1/29 site] vs 51.9% [56/108 site], p

Abstract 3425: Overexpression of TRIM44 contributes to malignant outcome in upper GI tract cancer

Recent studies have shown that some members of the tripartite motif-containing protein (TRIM) family, which function as important regulators for carcinogenesis. In this study, we tested whether TRIM44 (11p13) acts as a cancer-promoting gene through overexpression in gastric cancer (GC) and esophageal squamous cell carcinoma (ESCC). We analyzed 7 GC and 14 ESCC cell lines for in vitro analysis. We also analyzed 113 GC and 68 ESCC primary tumors, which were curatively resected in our hospital between 1998 and 2008. As the results, expression of the TRIM44 protein was detected in GC and ESCC cell lines (2/7 cell lines; 29% and 8/14; 57%, respectively) and primary tumor samples of GC and ESCC (24/113 cases; 24% and 39/68; 57%, respectively). Knockdown of TRIM44 expression using several specific siRNAs inhibited cell proliferation and migration and invasion in TRIM44-overexpressing GC cell, and inhibited cell migration and invasion in TRIM44-overexpressing ESCC. Using immunohistochemical analysis, overexpression of the TRIM44 was significantly correlated with an advanced type of macroscopic appearance, lymphatic invasion, and higher recurrence rate in GC, and with the status of the lymph node metastasis in ESCC. TRIM44-overexpressing tumors had a worse overall rate of survival than those with non-expressing tumors in GC and ESCC tumors. Moreover, TRIM44 positivity was independently associated with worse outcome in multivariate analysis in GC tumors. These findings suggest that TRIM44 plays a crucial role in tumor progress through its overexpression, and highlight its usefulness as a novel predictor and potential therapeutic target in GC and ESCC. Citation Format: Tsutomu Kawaguchi. Overexpression of TRIM44 contributes to malignant outcome in upper GI tract cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3425. doi:10.1158/1538-7445.AM2015-3425