Tumor-isolated Cutibacterium acnes as an effective tumor suppressive living drug.

The two major challenges in cancer treatment are reducing the side effects and minimizing the cost of cancer treatment. A better therapy to treat cancer remains to be developed despite the presence of many therapeutic options. Here, we present bacterial therapy for treating cancer using tumor-isolated Cutibacterium acnes, which is safe to use, has minimal side effects compared to chemotherapeutic drugs, and most importantly, targets the tumor microenvironment due to the bacterium's anaerobic nature. It activates the immune system, and the immune cells effectively penetrate through the tumor tissue and form an immunologic hub inside, explicitly targeting the tumor and destroying the cells. This bacterial therapy is a new cost-effective innovative treatment.

Discovery of Intratumoral Oncolytic Bacteria Toward Targeted Anticancer Theranostics.

Unveiling biomedical functions of tumor-resident microbiota is challenging for developing advanced anticancer medicines. This study demonstrates that isolated intratumoral bacteria, associated with natural purple photosynthetic bacteria, have inherent biocompatibility and strong immunogenic anticancer efficacies. They preferentially grow and proliferate within a targeted tumor milieu, which effectively causes immune cells to infiltrate the tumor and provoke strong anticancer responses in various syngeneic mouse models, including colorectal cancer, sarcoma, metastatic lung cancer, and extensive drug-resistant breast cancer. Furthermore, these functional bacteria-treated mice exhibit excellent anticancerous responses and have significantly prolonged survival rates with effective immunological memory. Light-harvesting nanocomplexes of microbial consortia of intratumoral bacteria and purple photosynthetic bacteria can diagnose tumors using bio-optical-window near-infrared light, making them useful theranostic agents for highly targeted immunological elimination of the tumor and for precisely marking tumor location.

Multimerization of small G-protein H-Ras induced by chemical modification at hyper variable region with caged compound.

The lipid-anchored small G protein Ras is a central regulator of cellular signal transduction processes, thereby functioning as a molecular switch. Ras forms a nanocluster on the plasma membrane by modifying lipids in the hypervariable region (HVR) at the C-terminus to exhibit physiological functions. In this study, we demonstrated that chemical modification of cysteine residues in HVR with caged compounds (instead of lipidation) induces multimerization of H-Ras. The sulfhydryl-reactive caged compound, 2-nitrobenzyl bromide, was stoichiometrically incorporated into the cysteine residue of HVR and induced the formation of the Ras multimer. Light irradiation induced the elimination of the 2-nitrobenzyl group, resulting in the conversion of the multimer to a monomer. Size-exclusion chromatography coupled with high-performance liquid chromatography and small-angle x-ray scattering analysis revealed that H-Ras forms a pentamer. Electron microscopic observation of the multimer showed a circular ring shape, which is consistent with the structure estimated from x-ray scattering. The shape of the multimer may reflect the physiological state of Ras. It was suggested that the multimerization and monomerization of H-Ras were controlled by modification with a caged compound in HVR under light irradiation.

Interaction of a novel fluorescent GTP analogue with the small G-protein K-Ras.

A novel fluorescent guanosine 5'-triphosphate (GTP) analogue, 2'(3')-O-{6-(N-(7-nitrobenz-2-oxa-l,3-diazol-4-yl)amino) hexanoic}-GTP (NBD-GTP), was synthesized and utilized to monitor the effect of mutations in the functional region of mouse K-Ras. The effects of the G12S, A59T and G12S/A59T mutations on GTPase activity, nucleotide exchange rates were compared with normal Ras. Mutation at A59T resulted in reduction of the GTPase activity by 0.6-fold and enhancement of the nucleotide exchange rate by 2-fold compared with normal Ras. On the other hand, mutation at G12S only slightly affected the nucleotide exchange rate and did not affect the GTPase activity. We also used NBD-GTP to study the effect of these mutations on the interaction between Ras and SOS1, a guanine nucleotide exchange factor. The mutation at A59T abolished the interaction with SOS1. The results suggest that the fluorescent GTP analogue, NBD-GTP, is applicable to the kinetic studies for small G-proteins.

Photocontrol of the GTPase activity of the small G protein K-Ras by using an azobenzene derivative.

The small G protein Ras is a central regulator of cellular signal transduction processes, functioning as a molecular switch. Switch mechanisms utilizing conformational changes in nucleotide-binding motifs have been well studied at the molecular level. Azobenzene is a photochromic molecule that undergoes rapid and reversible isomerization between the cis and trans forms upon exposure to ultraviolet and visible light irradiation, respectively. Here, we introduced the sulfhydryl-reactive azobenzene derivative 4-phenylazophenyl maleimide (PAM) into the nucleotide-binding motif of Ras to regulate the GTPase activity by photoirradiation. We prepared four Ras mutants (G12C, Y32C, I36C, and Y64C) that have a single reactive cysteine residue in the nucleotide-binding motif. PAM was stoichiometrically incorporated into the cysteine residue of the mutants. The PAM-modified mutants exhibited reversible alterations in GTPase activity, nucleotide exchange rate, and interaction between guanine nucleotide exchange factor and Ras, accompanied by photoisomerization upon exposure to ultraviolet and visible light irradiation. The results suggest that incorporation of photochromic molecules into its nucleotide-binding motif enables photoreversible control of the function of the small G protein Ras.