# The Synergistic Effects of rhArg with Bcl-2 Inhibitors or Metformin Co-Treatment in Multiple Cancer Cell Models

## TL;DR

This study shows that combining rhArg with Bcl-2 inhibitors or metformin improves cancer cell death and cell cycle arrest across multiple cancer types.

## Contribution

The novel contribution is the discovery of synergistic effects between rhArg and Bcl-2 inhibitors or metformin in various cancer cell models.

## Key findings

- Combining rhArg with ABT263 significantly increased apoptosis and cell cycle arrest in U251 cells.
- rhArg + metformin showed time-dependent synergy in cancer cell models.
- rhArg + ABT263 was more effective than other amino acid depletion agents.

## Abstract

Background: Recombinant human arginase (rhArg) has been proven to exhibit an anticancer effect via arginine starvation. To further improve the efficacy of rhArg, we examined the feasibility of a combination strategy with Bcl-2 inhibitors (ABT263 and ABT199) or an antidiabetic drug (metformin) and investigated the mechanistic basis for these strategies. Methods: The combination effects were evaluated in a panel of human cancer cell lines modeling pancreatic ductal carcinoma (PDAC), triple-negative breast cancer (TNBC), colorectal cancer (CRC) and glioblastoma (GBM). Western blot analysis was used to evaluate the expression of apoptotic and cell cycle markers. MTT assay was used to evaluate the combination efficacy. Flow cytometric assays were used to investigate the apoptotic and cell cycle effects. Results: The combination of rhArg with sublethal doses of ABT263 significantly induced dose-dependent apoptosis, with elevated expression of apoptotic markers and a CI of 0.47 in U251. The combination inhibited CDK2 and cyclin A expression, indicating that the observed synergy also resulted from cell cycle arrest. We also found that rhArg + metformin was synergistic in a time-dependent manner. Compared to other amino acid depletion agents, rhArg + ABT263 was the most favorable combination pair. Conclusions: The combination of rhArg and ABT263 enhanced apoptosis and cell cycle arrest, demonstrating a potential broad-spectrum antitumor strategy.