Identification of a new pharmacological activity of the phenylpiperazine derivative naftopidil: tubulin-binding drug

Abstract

The phenylpiperazine derivative naftopidil is an α 1 -adrenoceptor (AR) antagonist that has been used clinically to treat benign prostatic hyperplasia. In our drug repositioning research, naftopidil shows the unique growth-inhibitory effects. Naftopidil inhibits cell cycle progression not only in cancer cells, but also in fibroblasts and vascular endothelial cells. Naftopidil-inhibited cell cycle progression is independent of α 1 -AR expression in cells. Therefore, the antiproliferative effects of naftopidil may be due to the off-target effects of the drug. In this study, we attempted to identify the offtarget molecules of naftopidil using the magnetic nanobeads, ferrite glycidyl metharcrylate (FG) beads. Similar to naftopidil, its derivatives TG09-01 and TG09-02, which were introduced with amino groups for immobilizing to FG beads, inhibited cell growth in human HT29 colon adenocarcinoma cells. Both derivatives were associated with inhibition of cell cycle progression in HT29 cells. This observation is consistent with that seen with naftopidil. Using TG09-02-immobilized FG beads, α-and β-tubulins were identified as the specific binding proteins of naftopidil. The tubulin polymerization assay clearly indicated that naftopidil bound directly to tubulin and inhibited the polymerization of tubulin. Other phenylpiperazine derivatives, such as RS100329, BMY7378, and KN-62, also inhibited the polymerization of tubulin. These results suggest that phenylpiperazine derivatives including naftopidil may have broad spectrum of cellular cytotoxicity in various types of cells. In addition, the tubulin polymerization-inhibiting activity of phenylpiperazine derivatives may be a specific feature of the phenylpiperazine-based structure. These findings can allow us to design and synthesize new tubulin-binding drugs derived from naftopidil as a lead compound.

A prospective randomized controlled study on the Suppression of Prostate Cancer by Naftopidil (SNAP)

“…Furthermore, we confirmed that naftopidil induced apoptosis in prostatic cancer cell lines and human prostatic cancer tissues via inhibition of Smad2 phosphorylation-medicated transforming growth factor (TGF) beta activation [10]. Other inhibitory mechanisms proposed include activation of death receptors [11] and blocking tubulin formation [12]. The anti-proliferative effects of naftopidil on cell growth have been reported for human renal cancer cells, bladder cancer, cervical cancer, and malignant pleural mesothelioma [10,[13][14][15][16].…”

Interleukin‐6 induces VEGF secretion from prostate cancer cells in a manner independent of androgen receptor activation

“…At that time, we initiated 72 h treatment with either 10 ng/mL IL‐6, 1 or 10 μM cellular signaling inhibitors, or vehicle (0.1% DMSO). The cells were harvested by scraping, and whole cell lysates were prepared as previously described . Briefly, the cell surface was washed with ice‐cold PBS and then lysed with CelLytic™ (Sigma‐Aldrich Co.…”

“…Extracted proteins were separated by gel electrophoresis and transferred to Immobilon polyvinylidenedifluoride (PVDF) membranes following our previously reported protocol . Anti‐phospho‐Akt, anti‐Akt, anti‐phospho‐Stat3, anti‐Stat3 or anti‐β‐actin antibodies were used at dilutions of 1:1,000, 1:1,000, 1:2,000, 1:2,000, and 1:5,000, respectively.…”

Bim, Puma and Noxa upregulation by Naftopidil sensitizes ovarian cancer to the BH3-mimetic ABT-737 and the MEK inhibitor Trametinib

“…Moreover, it efficiently sensitized PC-3 xenograft cells to radiation and docetaxel-induced apoptosis 34,35 . Study of molecular mechanisms involved in apoptosis events highlighted that its action could be independent of α 1 -AR blocking 30,36 and it was reported that Naftopidil bound directly to tubulin and inhibited its polymerization 37 . Its anticancer activity led to the development of more potent Naftopidil derivatives whose lead molecule, HUHS1015, was reported to transcriptionally increase Noxa and Puma expression 38 .…”