Mutant p53 confers chemoresistance in non-small cell lung cancer by upregulating Nrf2

Targeting the duality of cancer

Cancer is the second leading cause of death in the United States, and is an increasing cause of death in the developing world. While there is great heterogeneity in the anatomic site and mutations involved in human cancer, there are common features, including immortal growth, angiogenesis, apoptosis evasion, and other features, that are common to most if not all cancers. However, new features of human cancers have been found as a result of clinical use of novel “targeted therapies,” angiogenesis inhibitors, and immunotherapies, including checkpoint inhibitors. These findings indicate that cancer is a moving target, which can change signaling and metabolic features based upon the therapies offered. It is well-known that there is significant heterogeneity within a tumor and it is possible that treatment might reduce the heterogeneity as a tumor adapts to therapy and, thus, a tumor might be synchronized, even if there is no major clinical response. Understanding this concept is important, as concurrent and sequential therapies might lead to improved tumor responses and cures. We posit that the repertoire of tumor responses is both predictable and limited, thus giving hope that eventually we can be more effective against solid tumors. Currently, among solid tumors, we observe a response of 1/3 of tumors to immunotherapy, perhaps less to angiogenesis inhibition, a varied response to targeted therapies, with relapse and resistance being the rule, and a large fraction being insensitive to all of these therapies, thus requiring the older therapies of chemotherapy, surgery, and radiation. Tumor phenotypes can be seen as a continuum between binary extremes, which will be discussed further. The biology of cancer is undoubtedly more complex than duality, but thinking of cancer as a duality may help scientists and oncologists discover optimal treatments that can be given either simultaneously or sequentially.

p53 and its mutants on the slippery road from stemness to carcinogenesis

Normal development, tissue homeostasis and regeneration following injury rely on the proper functions of wide repertoire of stem cells (SCs) persisting during embryonic period and throughout the adult life. Therefore, SCs employ robust mechanisms to preserve their genomic integrity and avoid heritage of mutations to their daughter cells. Importantly, propagation of SCs with faulty DNA as well as dedifferentiation of genomically altered somatic cells may result in derivation of cancer SCs, which are considered to be the driving force of the tumorigenic process. Multiple experimental evidence suggest that p53, the central tumor suppressor gene, plays a critical regulatory role in determination of SCs destiny, thereby eliminating damaged SCs from the general SC population. Notably, mutant p53 proteins do not only lose the tumor suppressive function, but rather gain new oncogenic function that markedly promotes various aspects of carcinogenesis. In this review, we elaborate on the role of wild type and mutant p53 proteins in the various SCs types that appear under homeostatic conditions as well as in cancer. It is plausible that the growing understanding of the mechanisms underlying cancer SC phenotype and p53 malfunction will allow future optimization of cancer therapeutics in the context of precision medicine.

Long noncoding and circular RNAs in lung cancer: advances and perspectives

Better understanding and management of lung cancer are needed. Although much has been learned from known protein coding genes, long noncoding RNAs (lncRNAs), a relatively new and fast evolving large family of transcripts, have recently generated much attention for new discoveries. LncRNAs play critical regulatory functions and are emerging as new players in tumorigenesis and phenotypic determinators of lung cancer. In this review, we highlight the latest development of lncRNAs, including circular RNAs in lung cancer. We start with well-characterized lncRNAs and circular RNAs as an oncogene or tumor suppressor and then extend our discussion on the impact of SNPs in lncRNA on its functions and lung cancer risk and the clinical applications of lncRNAs as biomarkers and therapeutic targets.

Cytoplasmic localization of Nrf2 promotes colorectal cancer with more aggressive tumors via upregulation of PSMD4

Differences in subcellular localization of Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) have been associated with poor outcomes in human cancers. However, the prognostic value of subcellular localization of Nrf2 in colorectal cancer and the underlying mechanism in tumor invasion remain unknown. We enrolled tumors from colorectal patients to evaluate Nrf2, NQO1, and HO-1 expression by immunohistochemistry. NQO1 and HO-1 positive tumors showed nearly complete expression of Nrf2 in the nucleus and/or showed partial expression in the nucleus/cytoplasm (nNrf2); however, tumors negative for NQO1 and HO-1 showed almost complete expression of Nrf2 in the cytoplasm and/or partial expression in the nucleus/cytoplasm (cNrf2). Kaplan-Meier and Cox regression analysis indicated poorer overall survival in patients with cNrf2 tumors than with nNrf2 tumors. Cell models provided evidence that cNrf2, rather than nNrf2, was responsible for cell invasion and soft agar growth triggered by activation of the NF-κB/AKT/β-catenin cascade. Mechanistically, cNrf2 persistently increased PSMD4 expression by the HIF1α/β-catenin axis, whereas PSMD4 reciprocally enhanced Nrf2 nuclear export by increasing CRM1 expression through p53 degradation. The mechanistic action of the cell model was further confirmed with a nude mouse animal model in which xenograft tumors induced by cNrf2 were nearly completely suppressed by the proteasomal inhibitor carfilzomib or the β-catenin inhibitor XAV939. We therefore suggest that PSMD4 or β-catenin might be potential targets for suppressing tumor aggressiveness, and consequently, improving outcomes in patients whose tumors express cNrf2.

Creating chemotherapeutic-resistant breast cancer cell lines: advances and future perspectives

The development of resistance remains the most significant impediment to generating effective treatments for cancer. In the modern age of personalized medicine, it is of critical importance to understand the principles of both innate and acquired resistance to achieve the most effective therapeutic outcomes. Significant differences exist between cancer cells that exhibit innate resistance verses those that acquire resistance over time. Studying the acquisition of resistance is essential to obtaining a complete understanding of how treatments contribute to disease recurrence and progression. This review will evaluate the current understanding of chemotherapeutic resistance and its role in personalized medicine. This review will also explore how generating resistant cells in culture is essential to the development of improved cancer therapeutics.

Targeting DNA Damage Response in the Radio(Chemo)therapy of Non-Small Cell Lung Cancer

Lung cancer is the leading cause of cancer death worldwide due to its high incidence and mortality. As the most common lung cancer, non-small cell lung cancer (NSCLC) is a terrible threat to human health. Despite improvements in diagnosis and combined treatments including surgical resection, radiotherapy and chemotherapy, the overall survival for NSCLC patients still remains poor. DNA damage is considered to be the primary cause of lung cancer development and is normally recognized and repaired by the intrinsic DNA damage response machinery. The role of DNA repair pathways in radio(chemo)therapy-resistant cancers has become an area of significant interest in the clinical setting. Meanwhile, some studies have proved that genetic and epigenetic factors can alter the DNA damage response and repair, which results in changes of the radiation and chemotherapy curative effect in NSCLC. In this review, we focus on the effect of genetic polymorphisms and epigenetic factors such as miRNA regulation and lncRNA regulation participating in DNA damage repair in response to radio(chemo)therapy in NSCLC. These may provide novel information on the radio(chemo)therapy of NSCLC based on the individual DNA damage response.