Metabolic Switch and Cytotoxic Effect of Metformin on Burkitt Lymphoma

SH2 domain-containing inositol 5-phosphatases support the survival of Burkitt lymphoma cells by promoting energy metabolism

Burkitt lymphoma cells (BL) exploit antigen-independent tonic signals transduced by the B-cell antigen receptor (BCR) for their survival, but the molecular details of the rewired BL-specific BCR signal network remain unclear. A loss of function screen revealed the SH2 domain-containing 5`-inositol phosphatase 2 (SHIP2) as a potential modulator of BL fitness. We characterized the role of SHIP2 in BL survival in several BL cell models and show that perturbing SHIP2 function renders cells more susceptible to apoptosis, while attenuating proliferation in a BCR-dependent manner. Unexpectedly, SHIP2 deficiency did neither affect PI3K survival signals nor MAPK activity, but attenuated ATP production. We found that an efficient energy metabolism in BL cells requires phosphatidylinositol-3,4-bisphosphate (PI(3,4)P2), which is the enzymatic product of SHIP proteins. Consistently, interference with the function of SHIP1 and SHIP2 augments BL cell susceptibility to PI3K inhibition. Notably, we provide here a molecular basis of how tonic BCR signals are connected to energy supply, which is particularly important for such an aggressively growing neoplasia. These findings may help to improve therapies for the treatment of BL by limiting energy metabolism through the inhibition of SHIP proteins, which renders BL cells more susceptible to the targeting of survival signals.

Drug transport by red blood cells

This review focuses on the role of human red blood cells (RBCs) as drug carriers. First, a general introduction about RBC physiology is provided, followed by the presentation of several cases in which RBCs act as natural carriers of drugs. This is due to the presence of several binding sites within the same RBCs and is regulated by the diffusion of selected compounds through the RBC membrane and by the presence of influx and efflux transporters. The balance between the influx/efflux and the affinity for these binding sites will finally affect drug partitioning. Thereafter, a brief mention of the pharmacokinetic profile of drugs with such a partitioning is given. Finally, some examples in which these natural features of human RBCs can be further exploited to engineer RBCs by the encapsulation of drugs, metabolites, or target proteins are reported. For instance, metabolic pathways can be powered by increasing key metabolites (i.e., 2,3-bisphosphoglycerate) that affect oxygen release potentially useful in transfusion medicine. On the other hand, the RBC pre-loading of recombinant immunophilins permits increasing the binding and transport of immunosuppressive drugs. In conclusion, RBCs are natural carriers for different kinds of metabolites and several drugs. However, they can be opportunely further modified to optimize and improve their ability to perform as drug vehicles.

Repurposing Metformin in hematologic tumor: State of art

Metformin is an ancient drug for the treatment of type 2 diabetes, and many studies now suggested that metformin can be used as an adjuvant drug in the treatment of many types of tumors. The mechanism of action of metformin for tumor treatment mainly involves: 1. activation of AMPK signaling pathway 2. inhibition of DNA damage repair in tumor cells 3. downregulation of IGF-1 expression 4. inhibition of chemoresistance and enhancement of chemotherapy sensitivity in tumor cells 5. enhancement of antitumor immunity 6. inhibition of oxidative phosphorylation (OXPHOS). Metformin also plays an important role in the treatment of hematologic tumors, especially in leukemia, lymphoma, and multiple myeloma (MM). The combination of metformin and chemotherapy enhances the efficacy of chemotherapy, and metformin reduces the progression of monoclonal gammopathy of undetermined significance (MGUS) to MM. The purpose of this review is to summarize the anticancer mechanism of metformin and the role and mechanism of action of metformin in hematologic tumors. We mainly summarize the studies related to metformin in hematologic tumors, including cellular experiments and animal experiments, as well as controlled clinical studies and clinical trials. In addition, we also focus on the possible side effects of metformin. Although a large number of preclinical and clinical studies have been performed and the role of metformin in preventing the progression of MGUS to MM has been demonstrated, metformin has not been approved for the treatment of hematologic tumors, which is related to the adverse effects of its high-dose application. Low-dose metformin reduces adverse effects and has been shown to alter the tumor microenvironment and enhance antitumor immune response, which is one of the main directions for future research.

Action Mechanism of Metformin and Its Application in Hematological Malignancy Treatments: A Review

Hematologic malignancies (HMs) mainly include acute and chronic leukemia, lymphoma, myeloma and other heterogeneous tumors that seriously threaten human life and health. The common effective treatments are radiotherapy, chemotherapy and hematopoietic stem cell transplantation (HSCT), which have limited options and are prone to tumor recurrence and (or) drug resistance. Metformin is the first-line drug for the treatment of type 2 diabetes (T2DM). Recently, studies identified the potential anti-cancer ability of metformin in both T2DM patients and patients that are non-diabetic. The latest epidemiological and preclinical studies suggested a potential benefit of metformin in the prevention and treatment of patients with HM. The mechanism may involve the activation of the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway by metformin as well as other AMPK-independent pathways to exert anti-cancer properties. In addition, combining current conventional anti-cancer drugs with metformin may improve the efficacy and reduce adverse drug reactions. Therefore, metformin can also be used as an adjuvant therapeutic agent for HM. This paper highlights the anti-hyperglycemic effects and potential anti-cancer effects of metformin, and also compiles the in vitro and clinical trials of metformin as an anti-cancer and chemosensitizing agent for the treatment of HM. The need for future research on the use of metformin in the treatment of HM is indicated.