Targeted Delivery of 5-Fluorouracil and Sonidegib via Surface-Modified ZIF-8 MOFs for Effective Basal Cell Carcinoma Therapy

Abstract

The therapeutic effectiveness of the most widely used anticancer drug 5-fluorouracil (5-FU) is constrained by its high metabolism, short half-life, and rapid drug resistance after chemotherapy. Although various nanodrug delivery systems have been reported for skin cancer therapy, their retention, penetration and targeting are still a matter of concern. Hence, in the current study, a topical gel formulation that contains a metal-organic framework (zeolitic imidazole framework; ZIF-8) loaded with 5-FU and a surface modified with sonidegib (SDG; acting as a therapeutic agent as well as a targeting ligand) (5-FU@ZIF-8 MOFs) is developed against DMBA-UV-induced BCC skin cancer in rats. The MOFs were prepared using one-pot synthesis followed by post drug loading and SDG conjugation. The optimized MOFs were incorporated into hyaluronic acid-hydroxypropyl methyl cellulose gel and further subjected to characterization. Enhanced skin deposition of the 5-FU@ZIF-8-SDG MOFs was observed using ex vivo skin permeation studies. Confocal laser microscopy studies showed that 5-FU@ZIF-8-SDG MOFs permeated the skin via the transfollicular pathway. The 5-FU@ZIF-8-SDG MOFs showed stronger cell growth inhibition in A431 cells and good biocompatibility with HaCaT cells. Histopathological studies showed that the efficacy of the optimized MOF gels improved as the epithelial cells manifested modest hyperplasia, nuclear pleomorphism, and dyskeratosis. Additionally, immunohistochemistry and protein expression studies demonstrated the improved effectiveness of the 5-FU@ZIF-8-SDG MOFs, which displayed a considerable reduction in the expression of Bcl-2 protein. Overall, the developed MOF gels showed good potential for the targeted delivery of multifunctional MOFs in topical formulations for treating BCC cancer.

Keywords: 5-fluorouracil; ZIF-8 MOF; basal cell carcinoma; sonidegib; topical drug delivery.

Figure 1

Characterization of MOFs. (A) presents the FTIR spectra of different samples: (a) 5−FU, (b) SDG, (c) ZIF−8 MOFs, (d) 5−FU@ZIF-8 and (e) 5−FU@ZIF-8-SDG Complex. (B) represents DSC thermograms of different samples: (a) SDG, (b) 5−FU, (c) ZIF−8 MOFs, (d) 5−FU@ZIF-8, and (e) 5−FU@ZIF−8−SDG MOFs. (C) represents the XRD pattern of different samples. (D) presents an SEM image of ZIF−8 MOFs at the 200 nm scale. (E) presents a TEM image of ZIF−8 MOFs at the 50 nm scale and (F) represents an AFM image of ZIF−8 MOFs representing the surface roughness. * in figure over “nm” is to denote that “nm” stands for nanometer.

Figure 2

Ex vivo permeation study. (A): Permeability of 5-FU from plain drug dispersed gel and 5-FU@ZIF-8-SDG MOF gel formulation at pH 6.8. (B): Permeability of SDGs from the plain drug dispersed gel and 5-FU@ZIF-8-SDG MOF gel formulation at pH 6.8. All the points in the graph are presented as Mean ± SD (n = 3).

Figure 3

Confocal images of the skin sections obtained at 6 h after treatment with plain FITC or ZIF-8 MOF. (A) Control skin, (B) plain FITC, (C) ZIF-8 MOFs with FITC, (D) 3D image indicating the depth of penetration of ZIF-8 MOFs with FITC, (E) ZIF-8 MOFs with FITC showing the deposition of MOFs alongside the hair shaft.

Figure 4

In vitro cytotoxicity assay for plain ZIF-8 MOFs, 5-FU@ZIF-8, and 5-FU@ZIF-8-SDG complex formulations on HaCaT cells and A431 cells.

Figure 5

In vitro cell uptake studies. (A): In vitro cell uptake studies of ZIF-8 MOFs, 5-FU@ZIF-8, and 5-FU@ZIF-8-SDG complex formulations in HaCaT cells. (B): In vitro cell uptake studies of ZIF-8 MOFs, 5-FU@ZIF-8, and 5-FU@ZIF-8-SDG complex formulations in A431 cells.

Figure 6

Photomicrographs of histopathological evaluation of rat skin stained with H and E in the primary skin irritation study. (A) Positive control, (B) Negative control, (C) 5-FU@ZIF-8-SDG gel, (D) ZIF-8 MOF gel, and (E) plain 5-FU and SDG gel.

Figure 7

Visual observation of the animals with different treatments. (A). Negative control (Group 1), (B). Positive control (Group 2), (C). 5-FU@ZIF-8-SDG gel formulation (Group 8), (D). Marketed formulation (Group 9).

Figure 8

Photomicrographs of histopathological evaluation of rat skin stained with H and E Negative in in vivo pharmacodynamics study (Magnification: 40X). (A): Negative control (Group 1); (B): Positive control (Group 2); (C): Marketed topical cream (Group 9); (D): 5-FU@ZIF-8-SDG gel treated (Group 8).

Figure 9

Immunohistochemistry results with different treatments. (A): Negative control; (B): Positive control; (C): 5-FU@ZIF-8-SDG-treated group; (D): Marketed cream.

Figure 10

Results of Western blot analysis. (A) Representative protein expression analysis by Western blot of animal tissue fractions. Lane 1 is the disease control sample, which shows relatively higher expression of Bcl-2 protein than the treated groups (Lanes 2 to 4 are the plain 5-FU & SDG gel, marketed formulation and 5-FU@ZIF-8-SDG gel, respectively). (B) β-actin bands, which were used as an internal control.