NEC14

Dimethyl Sulfoxide Induces Chemotherapeutic Resistance in the Treatment of Testicular Embryonal Carcinomas

DMSO is widely used as a solvent for chemotherapeutic drugs like CDDP in treating testicular embryonal carcinomas (ECs). However, it may induce differentiation and reduce drug efficacy in EC cells. Kita et al. investigated the effects of DMSO on two human EC cell lines (NEC8 and NEC14) by evaluating CDDP resistance, differentiation markers (Vimentin, Fibronectin, TRA-1-60, SSEA-1 and -3), stemness markers (SOX2 and OCT3/4), and DNA methylation status.

Results showed that DMSO significantly increased resistance to CDDP in NEC8 and NEC14 cells. CDDP resistance in NEC8 cells increased up to three times compared to control levels following exposure to 0.8% DMSO since the IC₅₀ values rose from 4.1 µM to 11.6 µM (Fig. 1A). NEC14 cells demonstrated approximately three times greater resistance to CDDP when treated with 0.8% DMSO (Fig. 1B). The drug efflux pumps MDR-1 and MRP-1 were not activated by DMSO in either cell line as shown in (Fig. 1C). The differentiation status of EC cells treated with DMSO was determined by analyzing the expression levels of Vimentin, Fibronectin, TRA-1-60, and SSEA-1 and -3 proteins. The expression of TRA-1-60 increased dose-dependently with DMSO exposure in NEC8 cells but remained unaffected in NEC14 cells. Both cell lines showed a dose-dependent reduction in Vimentin expression when treated with DMSO (Fig. 2A–B). Fibronectin expression remained unchanged (Fig. 2A). SSEA-1 and -3 expression was subtle and unaffected by DMSO (Fig. 2A–B). These results indicate that DMSO promoted aberrant differentiation in human EC cells. Additionally, DMSO reduced SOX2 protein expression dose-dependently in both cell lines, while OCT3/4 expression remained unchanged (Fig. 2A).

Fig. 1. DMSO enhances resistance to CDDP without induction of MDR-1 or MRP-1 in human EC cells (Kita H, Okamoto K, et al., 2016).

Fig. 2. DMSO perturbs differentiation and reduces the stemness characteristics of human embryonic carcinoma cells (Kita H, Okamoto K, et al., 2016).

Antimigration, Anti-Invasion, Antiproliferation snd Anti-Colony Formation Effects of MPHOSPH1 Knockdown in Embryonal Carcinoma Cell Lines

Testicular germ cell tumors (TGCTs) are prevalent in young men, with non-seminomas having a worse prognosis than pure seminomas. MPHOSPH1, a kinesin superfamily protein, is involved in cytokinesis and is upregulated in various cancers, potentially interacting with STAT3 signaling. Abe et al. examined the antitumor effect of MPHOSPH1 knockdown in embryonal carcinoma cell lines. Both of the siMPHOSPH1-transfected embryonal carcinoma cell lines, NEC8 and NEC14, showed reduced cell migration and invasion compared to the control siRNA-transfected cells (p<0.001 for both) (Fig. 3B and C). Similarly, reduced cell proliferation and colony formation were also recognized in NEC8 and NEC14 (p<0.001 for both) (Fig. 3D and E).

Fig. 3. The efficacy of MPHOSPH1 knockdown using small-interfering RNA (siRNA) (Abe T, Kohashi K, et al., 2018).