MKN-28

Response to CDDP-Induced Cell Death in Both Parental and CDDP-Resistant GC Cell Lines

Gastric cancer (GC) is one of the most common causes of cancer-related death in the world and cisplatin (CDDP) is one of the important chemotherapeutic agents. CDDP resistance is the major challenge that dramatically decreases the chemotherapeutic efficiency and patient survival rate of advanced GC. Therefore, Mora-Lagos et al. aimed to develop and characterize CDDP-resistant GC cell lines (AGS R-CDDP and MKN-28 R-CDDP) by stepwise drug selection and investigate the underlying molecular mechanism of CDDP chemoresistance to identify novel chemotherapeutic targets.

As shown in Fig 1, flow cytometry data (annexin V/PI staining) showed significantly lower cell death rate in CDDP-resistant cells than that in parental cell lines. Cell death rate of AGS R-CDDP was 14.5% in comparison to 47.5% in AGS cells (Fig 1A). AGS R-CDDP cells exhibited lower live cell population compared to that of AGS cells (Fig 1B vs. 1C). The representative controls are in Fig 1D (AGS WT) and 1E (AGS R-CDDP). Cell death rate of MKN-28 R-CDDP was 40.8% in comparison to 59.2% in parental cells (P<0.01; Fig 1F). MKN-28 R-CDDP cells also showed lower live cell population compared to that of MKN-28 cells (Fig 1G vs. 1H). The representative controls are in Fig 1I (MKN-28 WT) and 2J (MKN-28 R-CDDP).

Fig. 1. Cell death analysis through flow cytometry with annexin-V and PI) staining of AGS and MKN28 cells treated with cisplatin (Mora-Lagos B, Cartas-Espinel I, et al., 2020).

MSLN-CAR NK Cells Specifically Targeted MSLN-Positive Cancer Cell Lines In Vitro

Chimeric antigen receptor (CAR) NK cell therapy faces challenges in solid tumors due to limited tumor-specific targets and low efficacy. Mesothelin (MSLN) has been considered as a candidate target for gastric cancer immunotherapy. However, the anti-tumor activity of anti-MSLN CAR NK cells has not been investigated. In this study, Cao's team engineered and characterized MSLN-targeted CAR NK-92 cells (MSLN-CAR NK) for their cytotoxic potential to specifically target MSLN-positive gastric cancer cells in vitro and in vivo.

First, to test the cytotoxicity of CAR NK cells, they generated luciferase/GFP-labeled gastric cancer cell lines (N87 GL, MKN-28 GL, AGS GL, Huh-7 GL; Fig. 2A). In 6-hour killing assays, MSLN-CAR NK cells displayed significantly stronger cytotoxic activity against MSLN-positive (N87 GL, MKN-28 GL, AGS GL) compared to CD19-CAR NK or parental NK-92 cells at high effector:target ratios. This effect was not observed in MSLN-negative Huh-7 GL cells (Fig. 2B). ELISA analysis further demonstrated that MSLN-CAR NK cells secreted increased amounts of IFN-γ, GM-CSF, Granzyme B and perforin when co-cultured with MSLN-positive gastric cancer cells, which was consistent with the qPCR data. The target-dependent degranulation and cytokine production observed were not observed in control cells (Fig. 2C). Taken together, these data show that MSLN-CAR NK cells have the potential to specifically kill MSLN-expressing gastric cancer cells.

Fig. 2. MSLN-CAR NK cells showed strong antitumor activity against MSLN-positive gastric cancer cell lines in vitro (Cao B H, Liu M T, et al., 2021).