Cancer chemoresistance and its mechanisms: Associated molecular factors and its regulatory role

Strategies to enhance the response of liver cancer to pharmacological treatments

In contrast to other types of cancers, there is no available efficient pharmacological treatment to improve the outcomes of patients suffering from major primary liver cancers, i.e., hepatocellular carcinoma and cholangiocarcinoma. This dismal situation is partly due to the existence in these tumors of many different and synergistic mechanisms of resistance, accounting for the lack of response of these patients, not only to classical chemotherapy but also to more modern pharmacological agents based on the inhibition of tyrosine kinase receptors (TKIs) and the stimulation of the immune response against the tumor using immune checkpoint inhibitors (ICIs). This review summarizes the efforts to develop strategies to overcome this severe limitation, including searching for novel drugs derived from synthetic, semisynthetic, or natural products with vectorial properties against therapeutic targets to increase drug uptake or reduce drug export from cancer cells. Besides, immunotherapy is a promising line of research that is already starting to be implemented in clinical practice. Although less successful than in other cancers, the foreseen future for this strategy in treating liver cancers is considerable. Similarly, the pharmacological inhibition of epigenetic targets is highly promising. Many novel "epidrugs," able to act on "writer," "reader," and "eraser" epigenetic players, are currently being evaluated in preclinical and clinical studies. Finally, gene therapy is a broad field of research in the fight against liver cancer chemoresistance, based on the impressive advances recently achieved in gene manipulation. In sum, although the present is still dismal, there is reason for hope in the non-too-distant future.

Notch signaling pathway in cancer: from mechanistic insights to targeted therapies

Notch signaling, renowned for its role in regulating cell fate, organ development, and tissue homeostasis across metazoans, is highly conserved throughout evolution. The Notch receptor and its ligands are transmembrane proteins containing epidermal growth factor-like repeat sequences, typically necessitating receptor-ligand interaction to initiate classical Notch signaling transduction. Accumulating evidence indicates that the Notch signaling pathway serves as both an oncogenic factor and a tumor suppressor in various cancer types. Dysregulation of this pathway promotes epithelial-mesenchymal transition and angiogenesis in malignancies, closely linked to cancer proliferation, invasion, and metastasis. Furthermore, the Notch signaling pathway contributes to maintaining stem-like properties in cancer cells, thereby enhancing cancer invasiveness. The regulatory role of the Notch signaling pathway in cancer metabolic reprogramming and the tumor microenvironment suggests its pivotal involvement in balancing oncogenic and tumor suppressive effects. Moreover, the Notch signaling pathway is implicated in conferring chemoresistance to tumor cells. Therefore, a comprehensive understanding of these biological processes is crucial for developing innovative therapeutic strategies targeting Notch signaling. This review focuses on the research progress of the Notch signaling pathway in cancers, providing in-depth insights into the potential mechanisms of Notch signaling regulation in the occurrence and progression of cancer. Additionally, the review summarizes pharmaceutical clinical trials targeting Notch signaling for cancer therapy, aiming to offer new insights into therapeutic strategies for human malignancies.

Overview of BH3 mimetics in ovarian cancer

Ovarian carcinoma is the leading cause of gynecological cancer-related death, still with a dismal five-year prognosis, mainly due to late diagnosis and the emergence of resistance to cytotoxic and targeted agents. Bcl-2 family proteins have a key role in apoptosis and are associated with tumor development/progression and response to therapy in different cancer types, including ovarian carcinoma. In tumors, evasion of apoptosis is a possible mechanism of resistance to therapy. BH3 mimetics are small molecules that occupy the hydrophobic pocket on pro-survival proteins, allowing the induction of apoptosis, and are currently under study as single agents and/or in combination with cytotoxic and targeted agents in solid tumors. Here, we discuss recent advances in targeting anti-apoptotic proteins of the Bcl-2 family for the treatment of ovarian cancer, focusing on BH3 mimetics, and how these approaches could potentially offer an alternative/complementary way to treat patients and overcome or delay resistance to current treatments.

Combining BNCT with carbonic anhydrase inhibition for mesothelioma treatment: Synthesis, in vitro, in vivo studies of ureidosulfamido carboranes

Mesothelioma is a malignant neoplasm of mesothelial cells caused by exposure to asbestos. The average survival time after diagnosis is usually nine/twelve months. A multi-therapeutic approach is therefore required to treat and prevent recurrence. Boronated derivatives containing a carborane cage, a sulfamido group and an ureido functionality (CA-USF) have been designed, synthesised and tested, in order to couple Boron Neutron Capture Therapy (BNCT) and the inhibition of Carbonic Anhydrases (CAs), which are overexpressed in many tumours. In vitro studies showed greater inhibition than the reference drug acetazolamide (AZ). To increase solubility in aqueous media, CA-USFs were used as inclusion complexes of hydroxypropyl β-cyclodextrin (HP-β-CD) in all the inhibition and cell experiments. BNCT experiments carried out on AB22 (murine mesothelioma) cell lines showed a marked inhibition of cell proliferation by CA-USFs, and in one case a complete inhibition of proliferation twenty days after neutron irradiation. Finally, in vivo neutron irradiation experiments on a mouse model of mesothelioma demonstrated the efficiency of combining CA IX inhibition and BNCT treatment. Indeed, a greater reduction in tumour mass was observed in treated mice compared to untreated mice, with a significant higher effect when combined with BNCT. For in vivo experiments CA-USFs were administered as inclusion complexes of higher molecular weight β-CD polymers thus increasing the selective extravasation into tumour tissue and reducing clearance. In this way, boron uptake was maximised and CA-USFs demonstrated to be in vivo well tolerated at a therapeutic dose. The therapeutic strategy herein described could be expanded to other cancers with increased CA IX activity, such as melanoma, glioma, and breast cancer.

Graphene Oxide (GO) for the Treatment of Bone Cancer: A Systematic Review and Bibliometric Analysis

Cancer is a severe disease that, in 2022, caused more than 9.89 million deaths worldwide. One worrisome type of cancer is bone cancer, such as osteosarcoma and Ewing tumors, which occur more frequently in infants. This study shows an active interest in the use of graphene oxide and its derivatives in therapy against bone cancer. We present a systematic review analyzing the current state of the art related to the use of GO in treating osteosarcoma, through evaluating the existing literature. In this sense, studies focused on GO-based nanomaterials for potential applications against osteosarcoma were reviewed, which has revealed that there is an excellent trend toward the use of GO-based nanomaterials, based on their thermal and anti-cancer activities, for the treatment of osteosarcoma through various therapeutic approaches. However, more research is needed to develop highly efficient localized therapies. It is suggested, therefore, that photodynamic therapy, photothermal therapy, and the use of nanocarriers should be considered as non-invasive, more specific, and efficient alternatives in the treatment of osteosarcoma. These options present promising approaches to enhance the effectiveness of therapy while also seeking to reduce side effects and minimize the damage to surrounding healthy tissues. The bibliometric analysis of photothermal and photochemical treatments of graphene oxide and reduced graphene oxide from January 2004 to December 2022 extracted 948 documents with its search strategy, mainly related to research papers, review papers, and conference papers, demonstrating a high-impact field supported by the need for more selective and efficient bone cancer therapies. The central countries leading the research are the United States, Iran, Italy, Germany, China, South Korea, and Australia, with strong collaborations worldwide. At the same time, the most-cited papers were published in journals with impact factors of more than 6.0 (2021), with more than 290 citations. Additionally, the journals that published the most on the topic are high impact factor journals, according to the analysis performed, demonstrating the high impact of the research field.

Harnessing Sulforaphane Potential as a Chemosensitizing Agent: A Comprehensive Review

Recent advances in oncological research have highlighted the potential of naturally derived compounds in cancer prevention and treatment. Notably, sulforaphane (SFN), an isothiocyanate derived from cruciferous vegetables including broccoli and cabbage, has exhibited potent chemosensitizing capabilities across diverse cancer types of bone, brain, breast, lung, skin, etc. Chemosensitization refers to the enhancement of cancer cell sensitivity to chemotherapy agents, counteracting the chemoresistance often developed by tumor cells. Mechanistically, SFN orchestrates this sensitization by modulating an array of cellular signaling pathways (e.g., Akt/mTOR, NF-κB, Wnt/β-catenin), and regulating the expression and activity of pivotal genes, proteins, and enzymes (e.g., p53, p21, survivin, Bcl-2, caspases). When combined with conventional chemotherapeutic agents, SFN synergistically inhibits cancer cell proliferation, invasion, migration, and metastasis while potentiating drug-induced apoptosis. This positions SFN as a potential adjunct in cancer therapy to augment the efficacy of standard treatments. Ongoing preclinical and clinical investigations aim to further delineate the therapeutic potential of SFN in oncology. This review illuminates the multifaceted role of this phytochemical, emphasizing its potential to enhance the therapeutic efficacy of anti-cancer agents, suggesting its prospective contributions to cancer chemosensitization and management.

From inflammation to metastasis: The central role of miR-155 in modulating NF-κB in cancer

Cancer is a multifaceted, complex disease characterized by unchecked cell growth, genetic mutations, and dysregulated signalling pathways. These factors eventually cause evasion of apoptosis, sustained angiogenesis, tissue invasion, and metastasis, which makes it difficult for targeted therapeutic interventions to be effective. MicroRNAs (miRNAs) are essential gene expression regulators linked to several biological processes, including cancer and inflammation. The NF-κB signalling pathway, a critical regulator of inflammatory reactions and oncogenesis, has identified miR-155 as a significant participant in its modulation. An intricate network of transcription factors known as the NF-κB pathway regulates the expression of genes related to inflammation, cell survival, and immunological responses. The NF-κB pathway's dysregulation contributes to many cancer types' development, progression, and therapeutic resistance. In numerous cancer models, the well-studied miRNA miR-155 has been identified as a crucial regulator of NF-κB signalling. The p65 subunit and regulatory molecules like IκB are among the primary targets that miR-155 directly targets to alter NF-κB activity. The molecular processes by which miR-155 affects the NF-κB pathway are discussed in this paper. It also emphasizes the miR-155's direct and indirect interactions with important NF-κB cascade elements to control the expression of NF-κB subunits. We also investigate how miR-155 affects NF-κB downstream effectors in cancer, including inflammatory cytokines and anti-apoptotic proteins.

Tephrosin Suppresses the Chemoresistance of Paclitaxel-Resistant Ovarian Cancer via Inhibition of FGFR1 Signaling Pathway

Ovarian cancer is the leading cause of death among gynecologic cancers. Paclitaxel is used as a standard first-line therapeutic agent for ovarian cancer. However, chemotherapeutic resistance and high recurrence rates are major obstacles to treating ovarian cancer. We have found that tephrosin, a natural rotenoid isoflavonoid, can resensitize paclitaxel-resistant ovarian cancer cells to paclitaxel. Cell viability, immunoblotting, and a flow cytometric analysis showed that a combination treatment made up of paclitaxel and tephrosin induced apoptotic death. Tephrosin inhibited the phosphorylation of AKT, STAT3, ERK, and p38 MAPK, all of which simultaneously play important roles in survival signaling pathways. Notably, tephrosin downregulated the phosphorylation of FGFR1 and its specific adapter protein FRS2, but it had no effect on the phosphorylation of the EGFR. Immunoblotting and a fluo-3 acetoxymethyl assay showed that tephrosin did not affect the expression or function of P-glycoprotein. Additionally, treatment with N-acetylcysteine did not restore cell cytotoxicity caused by a treatment combination made up of paclitaxel and tephrosin, showing that tephrosin did not affect the reactive oxygen species scavenging pathway. Interestingly, tephrosin reduced the expression of the anti-apoptotic factor XIAP. This study demonstrates that tephrosin is a potent antitumor agent that can be used in the treatment of paclitaxel-resistant ovarian cancer via the inhibition of the FGFR1 signaling pathway.