Modification of intracellular pH and thermosensitivity

Area of Science:

• Biochemistry
• Cell Biology
• Oncology

Background:

• Intracellular pH (pHi) and thermosensitivity are critical factors in cancer cell response to hyperthermia.
• Tumor microenvironments are often acidic, influencing treatment efficacy.
• Modulating ion transport mechanisms can alter cellular pH and heat sensitivity.

Purpose of the Study:

• To investigate the effects of amiloride, DIDS, and nigericin on SCK tumor cell pHi and thermosensitivity.
• To determine the combined impact of these inhibitors on cellular response to hyperthermia.
• To explore the potential for targeted enhancement of thermal damage in acidic tumor environments.

Main Methods:

• SCK tumor cells were treated with amiloride (Na+/H+ antiport inhibitor), DIDS (HCO3-/Cl- exchange inhibitor), and nigericin (K+/H+ ionophore).
• Intracellular pH was measured using the BCECF dye.
• Thermosensitivity was assessed following hyperthermia treatment at 43°C.
• Experiments were conducted at extracellular pH (pHe) 7.2 and 6.6.

Main Results:

• Hyperthermia alone decreased pHi by 0.15-0.20 pH units.
• Amiloride decreased pHi and enhanced thermal damage at pHe 6.6.
• DIDS enhanced amiloride's effects on pHi and thermosensitivity, particularly at pHe 6.6.
• Nigericin dose-dependently lowered pHi and increased thermosensitivity, with greater effects at pHe 6.6.
• A combination of nigericin, amiloride, and DIDS significantly reduced pHi and strongly sensitized cells to heat, especially at pHe 6.6.

Conclusions:

• Combined amiloride, DIDS, and nigericin effectively reduce SCK cell pHi and enhance thermosensitivity.
• The enhanced effects at acidic pHe (6.6) suggest potential for preferential targeting of acidic tumor tissues.
• This drug combination shows promise for improving hyperthermia treatment efficacy in tumors.