Improved ADM Penetration Distance and Therapeutic Efficiency in a Rabbit VX2 Liver Cancer Model by Relaxin Infusion Combined with Transcatheter Chemoembolization Through Hepatic Artery

Role of Relaxin Signaling in Cancer: A Review

The investigation into relaxin (RLN), additional RLN-like proteins, and RLN family peptide receptors (RXFP) has demonstrated their role in modulating the extracellular matrix (ECM), immune cells, specifically macrophages, and angiogenesis, with recent evidence showing an effect on signaling pathways in tumor cells. These findings serve as the basis for our narrative review to collate pertinent studies in this field and provide our perspective on their clinical and investigational significance. In the article, we discuss findings from pertinent studies focusing on evaluating the expression or effect of RLN1, RLN2, or RXFP1 in various cancers. We also briefly discuss the potential role that other RLN family peptides and their receptors play in cancer. Specifically, we delve into questions regarding RLN signaling in terms of parity/pregnancy-associated protection from mammary tumors, expression in tumors, detection in serum in the setting of cancers, effect on tumor-adjacent cells, effect on tumorigenesis depending on endogenous expression or delivery, and last, but not the least, impact on the effectiveness of anti-cancer therapies. We expect that summarizing the available literature to answer these questions will allow readers to understand the role of RLN-receptor interaction in cancer as well as identify areas of uncertainty and avenues for future investigation.

Drug delivery in transarterial chemoembolization of hepatocellular carcinoma: Ex vivo evaluation using transparent tissue imaging

In this study, we elucidated for the first time the role of anti-cancer drugs in transarterial chemoembolization (TACE) via direct visualization of the spatial distribution of drugs with respect to blood vessels in intact transparent hepatocellular carcinoma (HCC) tissues. To date, precise estimation of drug penetration into tumors using thin 3D tissue sections has been challenging. This study utilized the tissue optical clearing technique to resolve the lack of tissue clarity, thereby enabling deep tissue imaging for the quantitative assessment of drug delivery following TACE. We compared the drug delivery effect, time-dependent embolic effect, and immunogenic response following conventional TACE (cTACE), drug-eluting embolic TACE (DEE-TACE), and transarterial embolization (TAE) in a rat model of HCC. After each treatment, three-dimensional drug delivery was quantitatively evaluated via the transparent liver tumor imaging, and time-dependent tumor necrosis was analyzed by serial tumor harvesting and histological staining. The results showed that chemotherapeutic agents travel only short distances after cTACE (∼80µm) and DEE-TACE (∼110µm), whereas necrosis occurs extensively within 24 h of treatment (85.3-97.2% of tumor cells). In addition, the percentages of CD4 and IL-17+ CD4 T cells increased significantly following treatment; however, drug-loading did not appear to affect the immune response following TACE. In conclusion, transarterially delivered chemotherapeutic agents appeared to exert a limited role, owing to the rapid and overwhelming effect of embolization. STATEMENT OF SIGNIFICANCE: TACE has been widely used for the treatment of HCC, especially for unresectable intermediate and advanced HCCs. Drug use in TACE is expected to provide patients with synergistic therapeutic benefits with the effect of embolic agents; however, the role of chemotherapeutic agents in TACE remains controversial. This study quantitatively verified that chemotherapeutic agents travel only short distances after TACE, while necrosis occurs extensively within 24h, and drug loading does not significantly affect immune responses following TACE. Three-dimensional imaging of intact transparent HCC can contribute to a better understanding of drug delivery mechanisms associated with TACE and also reveal that drug use in TACE may need to be reconsidered and limited to situations when embolization is expected to be insufficient.