Prevalence and Risk Factors of Nephrotoxicity Among Adult Cancer Patients at Mbarara Regional Referral Hospital

The protective effect of hydroalcoholic Citrus aurantifolia peel extract against doxorubicin-induced nephrotoxicity

Background and purpose

Doxorubicin chemotherapy is a widely used treatment for various cancers, including breast, ovarian, and uterine cancers, among others. However, long-term use can cause nephrotoxicity side effects. Some citrus flavonoids have demonstrated nephroprotective activity; therefore, this study aimed to test the nephroprotective effectiveness of Citrus aurantifolia peel extract in protecting and reducing kidney damage caused by doxorubicin.

Experimental approach

Citrus aurantifolia peel was dried, ground, and extracted by ultrasonication (70% ethanol), then the extract was dried. Twenty-five female Sprague-Dawley rats were divided into 5 groups including the normal group (control), positive control (doxorubicin) group receiving doxorubicin at the repeated intraperitoneal (i.p.) dose of 4 mg/kg/day on days 2, 6, 10, and 14, and treatment groups receiving Citrus aurantifolia peel extract (CPE) with the doses of 100, 200, and 400 mg/kg/day orally for 14 days, and doxorubicin (4 mg/kg/day, i.p.) on days 2, 6, 10 and 14. On day 15, the rats were euthanized for the measurements of MDA, superoxide dismutase (SOD), catalase, kidney function (measuring blood urea nitrogen (BUN), creatinine, albumin serum levels), and renal histopathology.

Findings/Results

The CPE yield was 16.13%. CPE could significantly reduce the levels of MDA, and increase SOD and catalase activities compared with the doxorubicin-induced nephrotoxic model. CPE could increase renal function by reducing BUN and creatinine levels, increasing albumin, and improving the histopathology of the kidney.

Conclusion and implications

CPE has a potential effect as nephroprotective against doxorubicin-induced toxicity in renal through antioxidant capacities and increased renal function.

Zinc Oxide Nanoparticles and Cancer Chemotherapy: Helpful Tools for Enhancing Chemo-sensitivity and Reducing Side Effects?

Cancer chemotherapy is still a serious challenge. Chemo-resistance and destructive side effects of chemotherapy drugs are the most critical limitations of chemotherapy. Chemo-resistance is the leading cause of chemotherapy failure. Chemo-resistance, which refers to the resistance of cancer cells to the anticancer effects of chemotherapy drugs, is caused by various reasons. Among the most important of these reasons is the increase in the efflux of chemotherapy drugs due to the rise in the expression and activity of ABC transporters, the weakening of apoptosis, and the strengthening of stemness. In the last decade, a significant number of studies focused on the application of nanotechnology in cancer treatment. Considering the anti-cancer properties of zinc, zinc oxide nanoparticles have received much attention in recent years. Some studies have indicated that zinc oxide nanoparticles can target the critical mechanisms of cancer chemo-resistance and enhance the effectiveness of chemotherapy drugs. These studies have shown that zinc oxide nanoparticles can reduce the activity of ABC transporters, increase DNA damage and apoptosis, and attenuate stemness in cancer cells, leading to enhanced chemo-sensitivity. Some other studies have also shown that zinc oxide nanoparticles in low doses can be helpful in minimizing the harmful side effects of chemotherapy drugs. In this article, after a brief overview of the mechanisms of chemo-resistance and anticancer effects of zinc, we will review all these studies in detail.

Modulating the Activity of the Human Organic Cation Transporter 2 Emerges as a Potential Strategy to Mitigate Unwanted Toxicities Associated with Cisplatin Chemotherapy

Cisplatin (CDDP) stands out as an effective chemotherapeutic agent; however, its application is linked to the development of significant adverse effects, notably nephro- and ototoxicity. The human organic cation transporter 2 (hOCT2), found in abundance in the basolateral membrane domain of renal proximal tubules and the Corti organ, plays a crucial role in the initiation of nephro- and ototoxicity associated with CDDP by facilitating its uptake in kidney and ear cells. Given its limited presence in cancer cells, hOCT2 emerges as a potential druggable target for mitigating unwanted toxicities associated with CDDP. Potential strategies for mitigating CDDP toxicities include competing with the uptake of CDDP by hOCT2 or inhibiting hOCT2 activity through rapid regulation mediated by specific signaling pathways. This study investigated the interaction between the already approved cationic drugs disopyramide, imipramine, and orphenadrine with hOCT2 that is stably expressed in human embryonic kidney cells. Regarding disopyramide, its influence on CDDP cellular transport by hOCT2 was further characterized through inductively coupled plasma isotope dilution mass spectrometry. Additionally, its potential protective effects against cellular toxicity induced by CDDP were assessed using a cytotoxicity test. Given that hOCT2 is typically expressed in the basolateral membrane of polarized cells, with specific regulatory mechanisms, this work studied the regulation of hOCT2 that is stably expressed in Madin-Darby Canine Kidney (MDCK) cells. These cells were cultured in a matrix to induce the formation of cysts, exposing hOCT2 in the basolateral plasma membrane domain, which was freely accessible to experimental solutions. The study specifically tested the regulation of ASP+ uptake by hOCT2 in MDCK cysts through the inhibition of casein kinase II (CKII), calmodulin, or p56lck tyrosine kinase. Furthermore, the impact of this manipulation on the cellular toxicity induced by CDDP was examined using a cytotoxicity test. All three drugs-disopyramide, imipramine, and orphenadrine-demonstrated inhibition of ASP+ uptake, with IC50 values in the micromolar (µM) range. Notably, disopyramide produced a significant reduction in the CDDP cellular toxicity and platinum cellular accumulation when co-incubated with CDDP. The activity of hOCT2 in MDCK cysts experienced a significant down-regulation under inhibition of CKII, calmodulin, or p56lck tyrosine kinase. Interestingly, only the inhibition of p56lck tyrosine kinase demonstrated the capability to protect the cells against CDDP toxicity. In conclusion, certain interventions targeting hOCT2 have demonstrated the ability to reduce CDDP cytotoxicity, at least in vitro. Further investigations in in vivo systems are warranted to ascertain their potential applicability as co-treatments for mitigating undesired toxicities associated with CDDP in patients.