The Kras2 oncogene and mouse lung carcinogenesis

Stepwise nanoassembly of a single hairpin probe and its biosensing

Herein, we describe a novel trigger-induced DNA nanoassembly method using only one loop-stem shaped hairpin probe (HP) that consists of three different functional regions as a single building unit. The Region I is designed complementary to the trigger, while the Region II and Region III are projected to complementary with each other. When hybridized with the trigger, a toehold mediated strand displacement (TMSD) occurred on the strand of Region I, leading to the release of Region III for further hybridization with the Region II on another HP molecule and in turn inducing a stepwise growth of HP with the aid of polymerase. Unlike the conventional assembly approaches that rely on the sophisticated sequence design and complex operation, the single-HP nanoassembly is easy and fast. Moreover, because many HPs are opened during the assembly process, we exemplified the nanoassembly strategy by re-designing a new labeled hairpin probe to analyze the Kras oncogene with a high sensitivity and specificity. The present study demonstrated a novel promising DNA nanoassembly strategy for biological applications.

Lung adenocarcinomas: comparison between mice and men

A few human tumor types have been modeled in mice using genetic or chemical tools. The final goal of these efforts is to establish models that mimic not only the location and cellular origin of human cancers but also their genetic aberrations and morphologic appearances. The latter has been neglected by most investigators, and comparative histopathology of human versus mouse cancers is not readily available. This issue is exacerbated by the fact that some human malignancies comprise a whole spectrum of cancer subtypes that differ molecularly and morphologically. Lung cancer is a paradigm that appears not only as non-small cell and small-cell lung cancer but comprises a plethora of subtypes with distinct morphologic features. This review discusses species-specific and common morphological features of non-small cell lung cancer in mice and humans. Potential inconsistencies and the need for refined genetic tools are discussed in the context of a comparative analysis between commonly employed RAS-induced mouse tumors and human lung cancers.

Nrf2 prevents initiation but accelerates progression through the Kras signaling pathway during lung carcinogenesis

Nrf2 (Nfe2l2) governs cellular defenses against oxidative and electrophilic stresses and protects against chemical carcinogenesis. However, many cancers have been found to accumulate NRF2 protein, raising questions of precisely how Nrf2 contributes to carcinogenesis. In this report, we explored such questions in an established urethane-induced multistep model of lung carcinogenesis. Consistent with earlier observations, Nrf2-deficient (Nrf2(-/-)) mice exhibited a relative increase in tumor foci by 8 weeks after urethane administration. However, after 16 weeks, we observed a relative reduction in the number of tumors with more malignant characteristics in Nrf2(-/-) mice. Furthermore, all Nrf2(+/+) tumors harbored activated mutations in Kras, whereas Nrf2(-/-) tumors were rarely associated with similar Kras mutations. Overall, our results established that Nrf2 has two roles during carcinogenesis, one of which is preventive during tumor initiation and the second that promotes malignant progression. These findings establish Nrf2 inhibitors as rational tools to prevent malignant progression in lung cancer, whereas Nrf2 activators are more suited for lung cancer prevention.

Molecular networks in respiratory epithelium carcinomas

Current anti-cancer research is focused on cell surface receptors targeting, mainly epidermal growth factor receptor and vascular endothelial growth factor receptor, against which a few targeted agents are now available in clinical practice. Recent improvements of our understanding on the intracellular networks that participate in respiratory epithelium carcinogenesis have further elucidated the role of a variety of molecules that represent attractive targets for novel therapeutic strategies. The aim of this review is to explore the potential therapeutic opportunities of the manipulation of these pathways.

KRAS testing and its importance in colorectal cancer

Cetuximab and panitumumab are monoclonal antibodies used in the treatment of metastatic colorectal cancer (mCRC) by selectively targeting the epidermal growth factor receptor (EGFR) axis. Studies have shown that mutations in codons 12/13 of exon 2 of the KRAS gene render these therapies ineffective. As a result, the National Comprehensive Cancer Network and American Society of Clinical Oncology recommend KRAS mutation testing in mCRC. Appropriate testing depends on the coordinated efforts of the entire treatment team, including the pathologist, who selects the tumor sample and testing platform as well as interprets and reports results. In addition to describing rationale and methodologies for KRAS mutation testing, the authors also summarize their algorithmic approach and elaborate the potential role of newer molecular biomarkers to predict anti-EGFR resistance in wild-type KRAS tumors.

KRAS mutation testing in colorectal cancer

In the US, colorectal cancer is the third leading cause of cancer-related death. Approximately 20% of patients present with metastatic disease, and an additional 30% to 40% develop metastasis during the course of their disease. Patients with metastatic colon cancer have a 5-year survival rate of only 11%. Although surgery is the mainstay of treatment for early stage colon cancer, adjuvant treatment is usually used in patients advanced stage disease. In particular, epidermal growth factor receptor (EGFR) inhibitor therapies have emerged as effective treatments in a subset of patients with metastatic colorectal carcinoma. Two anti-EGFR biologics, cetuximab and panitumumab, have been approved by the Food and Drug Administrations for the treatment of refractory metastatic colorectal carcinoma. Mounting evidence has shown that these therapies are ineffective in tumors with mutations of codons 12 and 13 of exon 2 of the KRAS gene. Because of this compelling data, the National Comprehensive Cancer Network and the American Society of Clinical Oncology have recommended determination of KRAS mutation status in all patients with metastatic colorectal cancer who are candidates for anti-EGFR therapy. Anatomic pathologists play an integral role in coordinating the testing for KRAS mutations, as this assay is performed on tissue samples selected by the pathologist. Herein, the authors present an up-to-date review of the biologic, clinical, and laboratory aspects of KRAS mutation testing in colorectal cancer.