Tumor-targeted delivery of 8-hydroxyquinoline

Area of Science:

• Biochemistry
• Pharmacology
• Oncology

Background:

• RIF-1 mouse tumors exhibit elevated beta-glucuronidase activity compared to normal tissues.
• This enzymatic difference presents a potential target for selective drug delivery to tumors.

Purpose of the Study:

• To investigate the selective accumulation of 8-hydroxyquinoline (8-OHQ) in RIF-1 tumors.
• To evaluate the role of tumor acidification and hyperthermia in enhancing 8-OHQ delivery and retention.

Main Methods:

• Administered 8-hydroxyquinolyl-glucuronide (8-OHQ-GlcA) to mice bearing RIF-1 tumors.
• Tumors were pre-treated with D-glucose and NaHCO3 for acidification.
• Investigated the effect of mild hyperthermia (43°C) on 8-OHQ accumulation.
• Measured 8-OHQ levels in tumor and normal tissues over time.
• Assessed UDP-glucuronosyltransferase (UDPGT) activity in various tissues.

Main Results:

• Selective accumulation of 8-OHQ in RIF-1 tumors was observed after 8-OHQ-GlcA administration combined with tumor acidification.
• Peak 8-OHQ levels in tumors occurred between 30-60 minutes post-injection.
• Mild hyperthermia increased peak tumor 8-OHQ levels by 2-3 fold.
• Normal tissues like kidney and liver showed early 8-OHQ appearance and faster clearance compared to tumors.
• Low UDPGT activity in RIF-1 tumors contributed to prolonged 8-OHQ retention.

Conclusions:

• Selective tumor acidification and high beta-glucuronidase activity facilitate preferential 8-OHQ accumulation in RIF-1 tumors.
• Mild hyperthermia further enhances 8-OHQ levels in tumors.
• Low UDPGT activity in tumors plays a crucial role in the sustained retention of 8-OHQ, suggesting a viable strategy for targeted cancer therapy.