Prostate Cancer Cells Are Sensitive to Lysosomotropic Agent Siramesine through Generation Reactive Oxygen Species and in Combination with Tyrosine Kinase Inhibitors

Promoting reactive oxygen species accumulation to overcome tyrosine kinase inhibitor resistance in cancer

BACKGROUND

In tumor treatment, protein tyrosine kinase inhibitors (TKIs) have been extensively utilized. However, the efficacy of TKI is significantly compromised by drug resistance. Consequently, finding an effective solution to overcome TKI resistance becomes crucial. Reactive oxygen species (ROS) are a group of highly active molecules that play important roles in targeted cancer therapy including TKI targeted therapy. In this review, we concentrate on the ROS-associated mechanisms of TKI lethality in tumors and strategies for regulating ROS to reverse TKI resistance in cancer.

MAIN BODY

Elevated ROS levels often manifest during TKI therapy in cancers, potentially causing organelle damage and cell death, which are critical to the success of TKIs in eradicating cancer cells. However, it is noteworthy that cancer cells might initiate resistance pathways to shield themselves from ROS-induced damage, leading to TKI resistance. Addressing this challenge involves blocking these resistance pathways, for instance, the NRF2-KEAP1 axis and protective autophagy, to promote ROS accumulation in cells, thereby resensitizing drug-resistant cancer cells to TKIs. Additional effective approaches inducing ROS generation within drug-resistant cells and providing exogenous ROS stimulation.

CONCLUSION

ROS play pivotal roles in the eradication of tumor cells by TKI. Harnessing the accumulation of ROS to overcome TKI resistance is an effective and widely applicable approach.

Anti-tumour effects of lapatinib on HER2-positive canine prostatic carcinoma cell lines

Background

Canine prostatic carcinoma (cPC) is a urogenital tumour with a poor prognosis, for which no effective treatment has been established. Recently, it has been shown that human epidermal growth factor receptor type 2 (HER2) is overexpressed in cPC cells; however, the efficacy of HER2-targeted therapy remains unclear.

Aim

Investigate the anti-tumour effect of lapatinib on HER2-positive cPC cell lines.

Methods

Two cell lines (muPC and bePC) were established from two dogs with cPC and the effects of lapatinib treatment on cell proliferation, apoptosis, and HER2 downstream signalling were investigated. Furthermore, muPC was used to generate tumour-bearing mice, and the anti-tumour effects of lapatinib were examined in vivo.

Results

Lapatinib treatment inhibited the proliferation and phosphorylation of Erk1/2 and Akt, which are downstream signals of HER2. Furthermore, the TUNEL assay showed that lapatinib induced apoptosis in both cell lines. The muPC-engrafted nude mouse model showed that lapatinib significantly inhibited tumour growth and increased the area of necrotic tumour tissue compared to the vehicle-treated groups.

Conclusion

Lapatinib exerts anti-tumour effects on cPC cells by inhibiting HER-2 signalling.

Evaluation of the Antitumor Activity of Quaternary Ammonium Surfactants

Quaternary ammonium surfactants, due to their diverse chemical structure and their biological properties, can be used in medicine as DNA carriers, disinfectants, and antimicrobial and antitumor agents. In this study, using melanoma A375, colon adenocarcinoma HT-29 and normal human dermal fibroblast (NHDF) cells, we tested the hypothesis that the quaternary ammonium surfactants 2-dodecanoyloxyethyl)trimethylammonium bromide (DMM-11), 2-dodecanoyloxypropyl)trimethylammonium bromide (DMPM-11) and 2-pentadecanoyloxymethyl)trimethylammonium bromide (DMGM-14) act selectively against cancer cells. The results showed that these compounds led to the initiation of the apoptotic process of programmed cell death, as evidenced by the ratio of the relative expression of Bax protein to Bcl-2. The encapsulation of surfactants in liposomes allowed lower concentrations to be used. Moreover, encapsulation reduced their toxicity towards non-cancerous cells. The anticancer efficiency and apoptotic effect of the liposomal formulations with surfactants (DMM-11, DMPM-11 and DMGM-14) were higher than those of surfactant-free liposomes. Therefore, quaternary ammonium surfactant-loaded liposomes show significant potential as delivery vehicles for the treatment of melanoma and colon cancers. The use of nano-formulations offers the advantage of optimizing quaternary ammonium surfactant delivery for improved anticancer therapy.

Repositioning the antihistamine ebastine as an intracellular siRNA delivery enhancer

Small interfering RNAs (siRNAs) are promising therapeutics for the treatment of human diseases via the induction of sequence-specific gene silencing. To be functional, siRNAs require cytosolic delivery into target cells. However, state-of-the-art delivery systems mediate cellular entry through endocytosis and suffer from ineffective endosomal escape, routing a substantial fraction of the siRNA towards the lysosomal compartment. Cationic amphiphilic drugs (CADs) have been described to improve cytosolic siRNA delivery by the transient induction of lysosomal membrane permeabilization. In this work, we evaluated ebastine, an antihistamine CAD, for its ability to enhance cytosolic release of siRNA in a non-small cell lung cancer model. In particular, we demonstrated that ebastine can improve the siRNA-mediated gene silencing efficiency of a polymeric nanogel by 40-fold, outperforming other CAD compounds. Additionally, ebastine substantially enhanced gene knockdown of a cholesterol-conjugated siRNA, in two-dimensional (2D) cell culture as well as in three-dimensional (3D) tumor spheroids. Finally, ebastine could strongly promote siRNA delivery of lipid nanoparticles (LNPs) composed of a pH-dependent switchable ionizable lipid and with stable PEGylation, in contrast to state-of-the-art LNP formulations. Altogether, we identified ebastine as a potent and versatile siRNA delivery enhancer in cancer cells, which offers opportunities for drug combination therapy in oncology.

Lysosomes as a Target of Anticancer Therapy

Lysosomes are organelles containing acidic hydrolases that are responsible for lysosomal degradation and the maintenance of cellular homeostasis. They play an important role in autophagy, as well as in various cell death pathways, such as lysosomal and apoptotic death. Various agents, including drugs, can induce lysosomal membrane permeability, resulting in the translocation of acidic hydrolases into the cytoplasm, which promotes lysosomal-mediated death. This type of death may be of great importance in anti-cancer therapy, as both cancer cells with disturbed pathways leading to apoptosis and drug-resistant cells can undergo it. Important compounds that damage the lysosomal membrane include lysosomotropic compounds, antihistamines, immunosuppressants, DNA-damaging drugs, chemotherapeutics, photosensitizers and various plant compounds. An interesting approach in the treatment of cancer and the search for ways to overcome the chemoresistance of cancer cells may also be combining lysosomotropic compounds with targeted modulators of autophagy to induce cell death. These compounds may be an alternative in oncological treatment, and lysosomes may become a promising therapeutic target for many diseases, including cancer. Understanding the functional relationships between autophagy and apoptosis and the possibilities of their regulation, both in relation to normal and cancer cells, can be used to develop new and more effective anticancer therapies.