MicroRNA in colorectal cancer: from benchtop to bedside.

Colon carcinogenesis represents a stepwise progression from benign polyps to invasive adenocarcinomas and distant metastasis. It is believed that these pathologic changes are contributed by aberrant activation or inactivation of protein-coding proto-oncogenes and tumor suppressor genes. However, recent discoveries in microRNA (miRNA) research have reshaped our understanding of the role of non-protein-coding genes in carcinogenesis. In this regard, a remarkable number of miRNAs exhibit differential expression in colon cancer tissues. These miRNAs alter cell proliferation, apoptosis and metastasis through their interactions with intracellular signaling networks. From a clinical perspective, polymorphisms within miRNA-binding sites are associated with the risk for colon cancer, whereas miRNAs isolated from feces or blood may serve as biomarkers for early diagnosis. Altered expression of miRNA or polymorphisms in miRNA-related genes have also been shown to correlate with patient survival or treatment outcome. With further insights into miRNA dysregulation in colon cancer and the advancement of RNA delivery technology, it is anticipated that novel miRNA-based therapeutics will emerge.

Macroautophagy modulates cellular response to proteasome inhibitors in cancer therapy.

Macroautophagy and the ubiquitin-proteasome system are two complementary pathways for protein degradation. The former degrades long-lived proteins and damaged organelles while the later degrades short-lived proteins. Recent findings indicate that suppression of the ubiquitin-proteasome system by proteasome inhibitors induces macroautophagy through multiple pathways, including (1) accumulation of ubiquitinated proteins and activation of HDAC6; (2) activation of the IRE1-JNK pathway; (3) proteasomal stabilization of ATF4; (4) inhibition of mTOR complex 1 signaling; (5) reduced proteasomal degradation of LC3. Induction of macroautophagy attenuates the antitumor effect of proteasome inhibitors in various types of cancer. These findings suggest that inhibition of macroautophagy may represent a novel strategy to enhance cellular sensitivity to proteasome inhibition.

Emerging roles of the host defense peptide LL-37 in human cancer and its potential therapeutic applications.

Human cathelicidin LL-37, a host defense peptide derived from leukocytes and epithelial cells, plays a crucial role in innate and adaptive immunity. Not only does LL-37 eliminate pathogenic microbes directly but also modulates host immune responses. Emerging evidence from tumor biology studies indicates that LL-37 plays a prominent and complex role in carcinogenesis. Although overexpression of LL-37 has been implicated in the development or progression of many human malignancies, including breast, ovarian and lung cancers, LL-37 suppresses tumorigenesis in gastric cancer. These data are beginning to unveil the intricate and contradictory functions of LL-37. The reasons for the tissue-specific function of LL-37 in carcinogenesis remain to be elucidated. Here, we review the relationship between LL-37, its fragments and cancer progression as well as discuss the potential therapeutic implications of targeting this peptide.

Effects of high-impact mechanical loading on synovial cell cultures.

Cartilage metabolism in response to mechanical loading is an important subject in sports science and medicine. In animal studies high-impact exercise is known to stimulate bone adaptation and increase bone mass. However, mechanical impacts potentially induce tissue swelling and occasionally degradation of connective tissues in synovium and articular cartilage. These detrimental outcomes should be properly evaluated clinically and biochemically. Using two synovial cell cultures derived from normal and rheumatic tissues, we examined the biochemical effects of impulsive mechanical loads on expression and activities of influential proteolytic enzymes in joints, matrix metalloproteinases (MMPs), and their natural inhibitors, tissue inhibitors of metalloproteinases (TIMPs). The molecular analysis demonstrates that an impact factor (Im ), the ratio of the maximum force to weight, served as a good indicator for assessment of the inflammatory responses. The results showed that high impact above Im = 40 to 80 elevated not only expression but also enzymatic activities of MMPs. Key PointsHigh-impact loading elevated expression and activities of MMPs in synovial cell cultures.The impact factor was used to define in vitro intensity of high-impact loading.

Evaluation of semi-homogeneous assay formats for dual-specificity antibodies.

Dual specificity antibodies such as bispecific and Dual Action Fab (DAF) antibodies are emerging therapeutic products with powerful therapeutic potential. New bioassay formats are needed in order to monitor their dual biological activities. Here we describe the optimization and development of a "bridging" binding method in semi-homogenous (SH) assay format for a bi-specific antibody. In the SH assay format, the antigen and secondary antibodies are mixed directly with the sample solution. The bound complex is then captured onto a microtiter plate coated with the other antigen and subsequently detected by colorimetric methods. We demonstrated that an SH assay achieved comparable dynamic range, quantitation, and specificity to the conventional assay format where each reagent is added sequentially followed by separate washing and incubation steps. The SH assay requires fewer wash steps and the overall assay time is shortened by half, which translates to improved efficiency without any requirement for new equipment and reagents. Using the SH assay format, we also demonstrated that a DAF antibody which can bind to two different antigens with either arm could bind both antigens simultaneously in vitro. The SH assay format has broad application as an assay platform for assessing antigen binding properties efficiently.

Dysregulation of cellular signaling in gastric cancer.

The pathogenesis of gastric cancer is complex and related to multiple factors. Dysregulation of intracellular signaling pathways represents a common pathogenic mechanism and may be amenable to drug targeting. Multiple well-established oncogenic pathways, such as those mediated by cell cycle regulators, nuclear factor-kappaB, cyclooxygenase-2 and epidermal growth factor receptor are implicated in gastric carcinogenesis. Emerging evidence also underscores the importance of signaling pathways involved in the developmental process, including transforming growth factor-beta/bone morphogenetic protein signaling, Wnt/beta-catenin signaling, Hedgehog signaling and Notch signaling. Understanding their biological significance will provide a rational basis for drug development. Their relative importance and cross-talk in gastric carcinogenesis, however, are still not completely understood and warrant further investigation.