Special Agents Hunting Down Women Silent Killer: The Emerging Role of the p38α Kinase

Aziz NH, Teik CK, Shafiee MN, Kampan NC. New Predictive Biomarkers for Ovarian Cancer

Ovarian cancer is the eighth-most common cause of death among women worldwide. In the absence of distinctive symptoms in the early stages, the majority of women are diagnosed in advanced stages of the disease. Surgical debulking and systemic adjuvant chemotherapy remain the mainstays of treatment, with the development of chemoresistance in up to 75% of patients with subsequent poor treatment response and reduced survival. Therefore, there is a critical need to revisit existing, and identify potential biomarkers that could lead to the development of novel and more effective predictors for ovarian cancer diagnosis and prognosis. The capacity of these biomarkers to predict the existence, stages, and associated therapeutic efficacy of ovarian cancer would enable improvements in the early diagnosis and survival of ovarian cancer patients. This review not only highlights current evidence-based ovarian-cancer-specific prognostic and diagnostic biomarkers but also provides an update on various technologies and methods currently used to identify novel biomarkers of ovarian cancer.

Emerging roles of lamins and DNA damage repair mechanisms in ovarian cancer

Lamins are type V intermediate filament proteins which are ubiquitously present in all metazoan cells providing a platform for binding of chromatin and related proteins, thereby serving a wide range of nuclear functions including DNA damage repair. Altered expression of lamins in different subtypes of cancer is evident from researches worldwide. But whether cancer is a consequence of this change or this change is a consequence of cancer is a matter of future investigation. However changes in the expression levels of lamins is reported to have direct or indirect association with cancer progression or have regulatory roles in common neoplastic symptoms like higher nuclear deformability, increased genomic instability and reduced susceptibility to DNA damaging agents. It has already been proved that loss of A type lamin positively regulates cathepsin L, eventually leading to degradation of several DNA damage repair proteins, hence impairing DNA damage repair pathways and increasing genomic instability. It is established in ovarian cancer, that the extent of alteration in nuclear morphology can determine the degree of genetic changes and thus can be utilized to detect low to high form of serous carcinoma. In this review, we have focused on ovarian cancer which is largely caused by genomic alterations in the DNA damage response pathways utilizing proteins like RAD51, BRCA1, 53BP1 which are regulated by lamins. We have elucidated the current understanding of lamin expression in ovarian cancer and its implications in the regulation of DNA damage response pathways that ultimately result in telomere deformation and genomic instability.

Nuclear factor-erythroid 2-related factor 3 (NRF3) is low expressed in colorectal cancer and its down-regulation promotes colorectal cancer malignance through activating EGFR and p38/MAPK

Nuclear factor-erythroid 2-related factor 3 (NRF3), a nuclear transcription factor, has been implicated in various cellular processes including carcinogenesis. However, mechanisms underlying its regulation in carcinogenesis are unclear. Herein, we found that NRF3 is lowly expressed in colorectal cancer (CRC) tissues and cells, and NRF3 low-expressions in CRC tissue samples are associated with CRC carcinogenesis and poor patient outcomes. Nrf3-knockdown increased CRC cell growth, colony formation, and cell motility and invasion, and Nrf3-knockin dramatically decreased CRC cell growth and colony formation. Mechanistically, NRF3 increased CRC cell apoptosis and arrested cell G2/M stage. NRF3 was found to be reversely with epidermal growth factor receptor (EGFR) and p38. Strikingly, Nrf3-knockin dramatically decreased phosphorylated-EGFR at Tyrosine845 (pEGFR Tyr845) and phosphorylated-p38 at Threonine180/Tyrosine182 (p-p38 Thr180/Tyr182) expressions, and Nrf3-knockdown increased pEGFR Tyr845 and p-p38 Thr180/Tyr182. Moreover, NRF3 regulated EGFR and p38 down-stream molecules, protein kinase B (AKT), activating transcription factor (ATF) 2, and C/EBP homologous protein (CHOP) expressions. NRF3 loss-increased CRC growth through EGFR and p38 was confirmed in nude mice. Collectively, NRF3-loss in CRC cell increases EGFR and p38 phosphorylation activation, enhances cell proliferation and decreases cell apoptosis, and finally promotes CRC malignance.

Tolfenamic Acid Inhibits the Proliferation, Migration, and Invasion of Nasopharyngeal Carcinoma: Involvement of p38-Mediated Down-Regulation of Slug

PURPOSE

Tolfenamic acid (TA), a non-steroidal anti-inflammatory drug, is known to exhibit antitumor effects in various cancers apart from nasopharyngeal cancer (NPC). NPC exhibits high invasiveness, as well as metastatic potential, and patients continue to suffer from residual, recurrent, or metastatic disease even after chemoradiation therapy. Therefore, new treatment strategies are needed for NPC. In this study, we investigated the efficacy and molecular mechanisms of TA in NPC treatment.

MATERIALS AND METHODS

TA-induced cell death was detected by cell viability assay in the NPC cell lines, HNE1 and HONE1. Wound healing assay, invasion assay, and Western blot analysis were used to evaluate the antitumor effects of TA in NPC cell lines.

RESULTS

Treatment with TA suppressed the migration and invasion of HNE1 and HONE1 cells. Hepatocyte growth factor enhanced the proliferation, migration, and invasion abilities of NPC cells. This enhancement was successfully inhibited by TA treatment. Treatment with TA increased phosphorylation of p38, and the inhibition of p38 with SB203580 reversed the cytotoxic, anti-invasive, and anti-migratory effects of TA treatment in NPC cell lines. Moreover, inhibition of p38 also reversed the decrease in expression of Slug that was induced by TA treatment.

CONCLUSION

In conclusion, the activation of p38 plays a role in mediating TA-induced cytotoxicity and inhibition of invasion and migration via down-regulation of Slug.

p38α MAPK pathway: a key factor in colorectal cancer therapy and chemoresistance

Colorectal cancer (CRC) remains one of the most common malignancies in the world. Although surgical resection combined with adjuvant therapy is effective at the early stages of the disease, resistance to conventional therapies is frequently observed in advanced stages, where treatments become ineffective. Resistance to cisplatin, irinotecan and 5-fluorouracil chemotherapy has been shown to involve mitogen-activated protein kinase (MAPK) signaling and recent studies identified p38α MAPK as a mediator of resistance to various agents in CRC patients. Studies published in the last decade showed a dual role for the p38α pathway in mammals. Its role as a negative regulator of proliferation has been reported in both normal (including cardiomyocytes, hepatocytes, fibroblasts, hematopoietic and lung cells) and cancer cells (colon, prostate, breast, lung tumor cells). This function is mediated by the negative regulation of cell cycle progression and the transduction of some apoptotic stimuli. However, despite its anti-proliferative and tumor suppressor activity in some tissues, the p38α pathway may also acquire an oncogenic role involving cancer related-processes such as cell metabolism, invasion, inflammation and angiogenesis. In this review, we summarize current knowledge about the predominant role of the p38α MAPK pathway in CRC development and chemoresistance. In our view, this might help establish the therapeutic potential of the targeted manipulation of this pathway in clinical settings.

Targeting signaling pathways in epithelial ovarian cancer

Ovarian carcinoma (OC) is the most lethal gynecological malignancy. Response to platinum-based chemotherapy is poor in some patients and, thus, current research is focusing on new therapy options. The various histological types of OC are characterized by distinctive molecular genetic alterations that are relevant for ovarian tumorigenesis. The understanding of these molecular pathways is essential for the development of novel therapeutic strategies.