FOXM1-CD44 Signaling Is Critical for the Acquisition of Regorafenib Resistance in Human Liver Cancer Cells

Down-regulation of microRNA-23a promotes pancreatic ductal adenocarcinoma initiation and progression by up-regulation of FOXM1 expression

Transcriptional factor Forkhead box M1 (FOXM1) plays an important role in pancreatic ductal adenocarcinoma (PDAC) development and progression. The molecular mechanisms underlying its dysregulation remain unclear. We identified and functionally validated the microRNAs (miRNAs) that critically regulate FOXM1 expression in PDAC. The expression levels of miRNA-23a (miR-23a-3p and -5p) were altered in PDAC cell lines and their effects on FOXM1 signaling and cell proliferation and migration and tumorigenesis were examined in vitro and in vivo using mouse PDAC models. Compared with non-tumor pancreatic tissues, PDAC tissues and cell lines exhibited significantly reduced levels of miR-23a expression. Reduced miR-23a expression and concomitant increase in FOXM1 expression were also observed in acinar-to-ductal metaplasia and pancreatic intraepithelial neoplasia, the major premalignant lesions of PDAC. Transgenic expression of miR-23a reduced the expression of FOXM1 and suppressed cell proliferation and migration in PDAC cells, whereas the inhibitors of miR-23a did the opposite. Loss or reduced levels of miR-23a increased the levels of FOXM1 expression, while increased expression of FOXM1 down-regulated miR-23a expression, suggesting that miR-23a and FOXM1 were mutual negative regulators of their expression in PDAC cells. Therefore, the miR-23a/FOXM1 signaling axis is important in PDAC initiation and progression and could serve as an interventional or therapeutic target for patients with early or late stages of PDAC.

FOXM1: A small fox that makes more tracks for cancer progression and metastasis

Transcription factors (TFs) are indispensable for the modulation of various signaling pathways associated with normal cell homeostasis and disease conditions. Among cancer-related TFs, FOXM1 is a critical molecule that regulates multiple aspects of cancer cells, including growth, metastasis, recurrence, and stem cell features. FOXM1 also impact the outcomes of targeted therapies, chemotherapies, and immune checkpoint inhibitors (ICIs) in various cancer types. Recent advances in cancer research strengthen the cancer-specific role of FOXM1, providing a rationale to target FOXM1 for developing targeted therapies. This review compiles the recent studies describing the pivotal role of FOXM1 in promoting metastasis of various cancer types. It also implicates the contribution of FOXM1 in the modulation of chemotherapeutic resistance, antitumor immune response/immunotherapies, and the potential of small molecule inhibitors of FOXM1.

The Roles of Epigenetic Regulation and the Tumor Microenvironment in the Mechanism of Resistance to Systemic Therapy in Hepatocellular Carcinoma

Primary liver cancer is the sixth most common cancer and the third most common cause of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC) is a major histologic type with a poor prognosis owing to the difficulty in early detection, the chemotherapy resistance, and the high recurrence rate of the disease. Despite recent advancements in HCC prevention and diagnosis, over 50% of patients are diagnosed at Barcelona Clinic Liver Cancer Stage B or C. Systemic therapies are recommended for unresectable HCC (uHCC) with major vascular invasion, extrahepatic metastases, or intrahepatic lesions that have a limited response to transcatheter arterial chemoembolization, but the treatment outcome tends to be unsatisfactory due to acquired drug resistance. Elucidation of the mechanisms underlying the resistance to systemic therapies and the appropriate response strategies to solve this issue will contribute to improved outcomes in the multidisciplinary treatment of uHCC. In this review, we summarize recent findings on the mechanisms of resistance to drugs such as sorafenib, regorafenib, and lenvatinib in molecularly targeted therapy, with a focus on epigenetic regulation and the tumor microenvironment and outline the approaches to improve the therapeutic outcome for patients with advanced HCC.

Cancer Stem Cells in Hepatocellular Carcinoma: Intrinsic and Extrinsic Molecular Mechanisms in Stemness Regulation

Hepatocellular carcinoma (HCC) remains the most predominant type of liver cancer with an extremely poor prognosis due to its late diagnosis and high recurrence rate. One of the culprits for HCC recurrence and metastasis is the existence of cancer stem cells (CSCs), which are a small subset of cancer cells possessing robust stem cell properties within tumors. CSCs play crucial roles in tumor heterogeneity constitution, tumorigenesis, tumor relapse, metastasis, and resistance to anti-cancer therapies. Elucidation of how these CSCs maintain their stemness features is essential for the development of CSCs-based therapy. In this review, we summarize the present knowledge of intrinsic molecules and signaling pathways involved in hepatic CSCs, especially the CSC surface markers and associated signaling in regulating the stemness characteristics and the heterogeneous subpopulations within the CSC pool. In addition, we recapitulate the effects of crucial extrinsic cellular components in the tumor microenvironment, including stromal cells and immune cells, on the modulation of hepatic CSCs. Finally, we synopsize the currently valuable CSCs-targeted therapy strategies based on intervention in these intrinsic and extrinsic molecular mechanisms, in the hope of shedding light on better clinical management of HCC patients.