Oncogenomics: prospects for the future

SPERT gene silencing inhibits the growth of human colon cancer xenograft tumor in nude mice via p38MAPK/HSP27 signaling pathway

Colorectal cancer is one of the most common gastrointestinal malignancies and is also a disease of genetic heterogeneity. Our previous studies have shown that SPERT (sprermatid-associated protein) gene may be an underlying oncogene that is associated with the progression of the disease in colorectal cancer patients, and SPERT gene silencing can inhibit the proliferation of colorectal tumor cells and promote cell apoptosis. Here, we use the stably transfected human colorectal cancer cell line RKO to construct an animal xenograft model and study the effect of SPERT gene silencing on animal xenografts. The results showed that SPERT gene silencing can inhibit tumor growth in animals. In addition, through signaling pathway analysis, we found that the p38MAPK/HSP27 signaling pathway may be the molecular mechanism by which SPERT gene silencing inhibits the growth of xenograft tumors in nude mice. Combined with previous data, SPERT gene silencing has the same inhibitory effect on tumor growth in vitro and in vivo. These data suggest that SPERT gene may be a potential target for the treatment of colorectal cancer in clinic.

Prospects for personalized medicine with inhibitors targeting the RAS and PI3K pathways

Tumor genetic analyses have revealed that the signaling pathways regulated by PI3K and RAS are of fundamental importance in a wide variety of human neoplasms, leading to intensive efforts to develop therapeutics that block signaling through these two key pathways. Both pathways frequently undergo a variety of activating alterations, including oncogenic mutations, amplification events and loss of tumor-suppressor genes that are thought to confer aggressive growth properties and enhance survival on neoplastic cells. An attractive hypothesis is that these alterations provide an indication that a particular tumor is addicted to signaling through the affected pathway, thus may provide ideal candidate predictive biomarkers to target these inhibitors to appropriate patient populations. This review highlights recent preclinical progress made on understanding the predictive value of key pathway alterations in response to targeted therapeutics directed against PI3K, AKT, mTOR, BRAF and MEK, and the prospects for biomarker-driven clinical strategies for such inhibitors.

A systems biology perspective on cholangiocellular carcinoma development: focus on MAPK-signaling and the extracellular environment

BACKGROUND/AIMS

Multiple genes have been implicated in cholangiocellular carcinoma (CCC) development. However, the overall neoplastic risk is likely associated with a much lower number of critical physiological pathways.

METHODS

To investigate this hypothesis, we extracted all published genetic associations for the development of CCC from PubMed (genetic association studies, but also studies associating genes and CCC in general, i.e. functional studies in cell lines, genetic studies in humans, knockout mice etc.) and integrated CCC microarray data.

RESULTS

We demonstrated the MAPK pathway was consistently enriched in CCC. Comparing our data to genetic associations in HCC often successfully treated by a multityrosine kinase inhibitor, sorafenib, we demonstrated a similar overrepresentation of MAPK. In contrast, most cancer-related genetic studies focusing on genes related to transcription and cell cycle control, we consistently found genes coding for products in the extracellular environment to be significantly enriched. Thus, CCC must be regarded as developing in the context of an altered extracellular environment.

CONCLUSIONS

Our study suggests the liver microenvironment holds essential functions and structures key to CCC progression. Furthermore, we identified the MAPK signaling pathway consistently enriched, pointing towards a critical role in CCC development. These data may provide a rationale for treatment of CCC with sorafenib.

HDACi phenylbutyrate increases bystander killing of HSV-tk transfected glioma cells

Malignant glioma patients have a dismal prognosis with an urgent need of new treatment modalities. Previously developed gene therapies for brain tumors showed promising results in experimental animal models, but failed in clinical trials due to low transfection rates and insufficient expression of the transgene in tumor cells, as well as low bystander killing effects. We have previously shown that the histone deacetylase inhibitor 4-phenylbutyrate (4-PB) enhances gap junction communication between glioma cells in culture. In this study, we demonstrate an activation of recombinant HSV-tk gene expression, and a dramatic enhancement of gap junction-mediated bystander killing effect by administration of the HSV-tk prodrug ganciclovir together with 4-PB. These findings that 4-PB potentiates "suicide gene" expression as well as enhances gap junctional communication and bystander killing of tumor cells justify further testing of this paradigm as an adjunct to suicide gene therapy of malignant gliomas.