Cetuximab chemotherapy resistance: Insight into the homeostatic evolution of head and neck cancer (Review).

The complex evolution of genetic alterations in cancer that occurs in vivo is a selective process involving numerous factors and mechanisms. Chemotherapeutic agents that prevent the growth and spread of cancer cells induce selective pressure, leading to rapid artificial selection of resistant subclones. This rapid evolution is possible because antineoplastic drugs promote alterations in tumor­cell metabolism, thus creating a bottleneck event. The few resistant cells that survive in this new environment obtain differential reproductive success that enables them to pass down the newly selected resistant gene pool. The present review aims to summarize key findings of tumor evolution, epithelial­mesenchymal transition and resistance to cetuximab therapy in head and neck squamous cell carcinoma.

Involvement of Kallikrein-Related Peptidases in Normal and Pathologic Processes.

Human kallikrein-related peptidases (KLKs) are a subgroup of serine proteases that participate in proteolytic pathways and control protein levels in normal physiology as well as in several pathological conditions. Their complex network of stimulatory and inhibitory interactions may induce inflammatory and immune responses and contribute to the neoplastic phenotype through the regulation of several cellular processes, such as proliferation, survival, migration, and invasion. This family of proteases, which includes one of the most useful cancer biomarkers, kallikrein-related peptidase 3 or PSA, also has a protective effect against cancer promoting apoptosis or counteracting angiogenesis and cell proliferation. Therefore, they represent attractive therapeutic targets and may have important applications in clinical oncology. Despite being intensively studied, many gaps in our knowledge on several molecular aspects of KLK functions still exist. This review aims to summarize recent data on their involvement in different processes related to health and disease, in particular those directly or indirectly linked to the neoplastic process.

Study of small proline-rich proteins (SPRRs) in health and disease: a review of the literature.

Epithelial tissues are specialized to protect underlying tissues from environmental influences such as physical and chemical agents, infection by invasive microorganisms as well as water and heat loss. They are grouped into simple, transitional and stratified epithelia, which line the cavities and surfaces of structures throughout the body, and also form glands, separate compartments, regulate the exchange of molecules and act as sensory organs. Stratified epithelia such as the epidermis and the gingival and hard palate mucosa are in constant renewal, with cells proliferating in the lower layers, while the intermediate stratum and outermost layers undergo a tissue-specific process of differentiation to form a protective cornified barrier. This review focuses on a subclass of structural proteins, the small proline-rich proteins (SPRRs), which constitute cornified cell envelope precursors. Several studies have suggested that the SPRRs are related to increased epithelial proliferation and to malignant processes. Hence, we also review the literature for more extensive and in-depth profile of these proteins in cancer and other diseases. The understanding of SPRR functions has advanced in recent years, but many important questions about their role in pathophysiological processes remain unanswered, which stimulate new studies and approaches.