New therapeutic options opened by the molecular classification of gastric cancer

Gastric cancer (GC) is one of the most lethal and aggressive cancers, being the third cause of cancer related death worldwide. Even with radical gastrectomy and the latest generation of molecular chemotherapeutics, the numbers of recurrence and mortality remains high. This is due to its biological heterogeneity based on the interaction between multiple factors, from genomic to environmental factors, diet or infections with various pathogens. Therefore, understanding the molecular characteristics at a genomic level is critical to develop new treatment strategies. Recent advances in GC molecular classification provide the unique opportunity to improve GC therapy by exploiting the biomarkers and developing novel targeted therapy specific to each subtype. This article highlights the molecular characteristics of each subtype of gastric cancer that could be considered in shaping a therapeutic decision, and also presents the completed and ongoing clinical trials addressed to those targets. The implementation of the novel molecular classification system will allow a preliminary patient selection for clinical trials, a mandatory issue if it is desired to test the efficacy of a certain inhibitor to the given target. This will represent a substantial advance as well as a powerful tool for targeted therapy. Nevertheless, translating the scientific results into new personalized treatment opportunities is needed in order to improve clinical care, the survival and quality of life of patients with GC.

Knockdown of KRT17 by siRNA induces antitumoral effects on gastric cancer cells

BACKGROUND

Keratin 17 (KRT17) was shown to be an important molecular marker for predicting the carcinogenesis, progression, and prognosis of various cancer types. Our previous studies identified KRT17 as a possible biomarker for gastric cancer by gene microarray, with an elevated expression that occurred early during tumorigenesis and increased during tumor progression. Based on these findings, we aimed to investigate KRT17 biological functions in gastric adenocarcinoma and its possible use as a rational molecular target for anticancer therapy.

METHODS

We used RNA interference-mediated knockdown of KRT17 expression and analyzed the effects on cell proliferation, cell migration, and signal transduction in two gastric cell lines (AGS and NCI-N87) in vitro and on xenograft growth in vivo.

RESULTS

The functional analysis of KRT17 knockdown cell lines showed a decreased cell proliferation (with 42.36% ± 3.2%) and migration ability (with 37.2% ± 6.2%) relative to scrambled siRNA control. The in vivo tumorigenicity on nude mice exhibited a significant decrease in tumor weight with 69.14% in xenografts obtained from AGS cells and 84.43% in xeno-NCI-N87 tumors. The analysis on KRT17 knockdown outcome on intracellular signaling identifies AKT/mTOR as the main affected pathway that sustains proliferation and survival, and also the AMPKα1/CREB pathway that was recently shown to induce organ protection and antiinflammatory response.

CONCLUSIONS

Our results highlight KRT17 as a possible biomarker in gastric cancer promoting tumor growth, motility, and invasion, and suggest that KRT17 can be a valuable molecular target for development of anti-gastric cancer-specific therapies.

Therapies targeting cancer stem cells: Current trends and future challenges

Traditional therapies against cancer, chemo- and radiotherapy, have multiple limitations that lead to treatment failure and cancer recurrence. These limitations are related to systemic and local toxicity, while treatment failure and cancer relapse are due to drug resistance and self-renewal, properties of a small population of tumor cells called cancer stem cells (CSCs). These cells are involved in cancer initiation, maintenance, metastasis and recurrence. Therefore, in order to develop efficient treatments that can induce a long-lasting clinical response preventing tumor relapse it is important to develop drugs that can specifically target and eliminate CSCs. Recent identification of surface markers and understanding of molecular feature associated with CSC phenotype helped with the design of effective treatments. In this review we discuss targeting surface biomarkers, signaling pathways that regulate CSCs self-renewal and differentiation, drug-efflux pumps involved in apoptosis resistance, microenvironmental signals that sustain CSCs growth, manipulation of miRNA expression, and induction of CSCs apoptosis and differentiation, with specific aim to hamper CSCs regeneration and cancer relapse. Some of these agents are under evaluation in preclinical and clinical studies, most of them for using in combination with traditional therapies. The combined therapy using conventional anticancer drugs with CSCs-targeting agents, may offer a promising strategy for management and eradication of different types of cancers.