Defective drug uptake contributing to multidrug resistance in hepatoma cells can be evaluated in vitro

The Emerging Roles of Exosomes in the Chemoresistance of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common gastrointestinal malignancy with a leading incidence of cancer-related mortality worldwide. Despite the progress of treatment options, there remains low efficacy for patients with intermediate-advanced HCC, due to tumor metastasis, recurrence and chemoresistance. Increasing evidence suggests that exosomes in the tumor microenvironment (TME), along with other extracellular vesicles (EVs) and cytokines, contribute to the drug chemosensitivity of cancer cells. Exosomes, the intercellular communicators in various biological activities, have shown to play important roles in HCC progression. This review summarizes the underlying associations between exosomes and chemoresistance of HCC cells. The exosomes derived from distinct cell types mediate the drug resistance by regulating drug efflux, epithelial-mesenchymal transition (EMT), cancer stem cell (CSC) properties, autophagic phenotypes, as well as the immune response. In summary, TME-related exosomes can be a potential target to reverse chemoresistance and a candidate biomarker of drug efficacy in HCC patients.

Non-coding RNA in drug resistance of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has been one of the most highly lethal cancers. The acquisition of drug resistance accounts for the majority of poor effects of chemotherapy in HCC. Non-coding RNAs (ncRNAs) including miRNAs, long ncRNAs (lncRNAs), and circular RNA (circRNA) have been well-documented to participate in cancer occurrence and progression. Recently, multiple studies have highlighted the key roles of ncRNAs in chemoresistance of HCC. In addition, accumulating evidence has demonstrated that they can serve as biomarkers in diagnosis, treatment, and prognosis of HCC. In this review, we first overviewed up-to-date findings regarding miRNA and lncRNA in drug resistance of HCC, then summarized specific mechanisms that they modulate chemoresistance of HCC, and finally discussed their potential clinical application in overcoming the obstacle of HCC chemoresistance in the future.

Drug delivery and transport to solid tumors

PURPOSE

The purpose of this review is to provide an overview of the principles of and barriers to drug transport and delivery to solid tumors.

METHODS

This review consists of four parts. Part I provides an overview of the differences in the vasculature in normal and tumor tissues, and the relationship between tumor vasculature and drug transport. Part II describes the determinants of transport of drugs and particles across tumor vasculature into surrounding tumor tissues. Part III discusses the determinants and barriers of drug transport, accumulation, and retention in tumors. Part IV summarizes the experimental approaches used to enhance drug delivery and transport in solid tumors.

RESULTS

Drug delivery to solid tumors consists of multiple processes, including transport via blood vessels, transvascular transport, and transport through interstitial spaces. These processes are dynamic and change with time and tumor properties and are affected by multiple physicochemical factors of a drug, multiple tumor biologic factors, and as a consequence of drug treatments. The biologic factors, in turn, have opposing effects on one or more processes in the delivery of drugs to solid tumors.

CONCLUSION

The effectiveness of cancer therapy depends in part on adequate delivery of the therapeutic agents to tumor cells. A better understanding of the processes and contribution of these factors governing drug delivery may lead to new cancer therapeutic strategies.