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Relaxin expression from tumor-targeting adenoviruses and its intratumoral spread, apoptosis induction, and efficacy
Joo-Hang Kim1, Young-Sook Lee, Hoguen Kim
1Brain Korea 21 Project for Medical Sciences, Institute for Cancer Research, Yonsei Cancer Center, Yonsei University College of Medicine, 134 Shinchon-Dong, Seodaemun-Gu, Seoul, Korea.
Background:
The use of oncolytic adenoviruses as cancer gene therapy is limited by their uneven penetration and distribution in tumors. We investigated whether the expression of the cell matrix-degradative protein relaxin by adenovirus could improve adenovirus distribution and penetration in tumors.
Methods:
We generated relaxin-expressing, replication-incompetent (dl-lacZ-RLX) and -competent (Ad-deltaE1B-RLX) adenoviruses by inserting a relaxin gene into the E3 adenoviral region. Controls were parental adenoviruses (dl-lacZ and Ad-deltaE1B) and phosphate-buffered saline (PBS) (vehicle). Replication-incompetent viruses, which do not lyse cells, were used to assess transduction efficiency. Viral spread in tumor spheroids, made by dissecting tumor tissue into homogeneous fragments, was assessed by reporter gene (i.e., lacZ) expression. Tumor growth inhibition was assessed by injecting adenoviruses into xenograft tumors in athymic mice (n = 8 or 9). Overall survival was assessed by the Kaplan-Meier method. Extracellular matrix was examined with Masson's trichrome staining. Therapeutic efficacy was evaluated by assessing spontaneous pulmonary metastasis in the B16BL6 melanoma mouse model and growth inhibition of orthotopically implanted hepatoma (n = 4-6). All statistical tests were two-sided.
Results:
In tumor spheroids and established solid tumors in vivo, transduction with dl-lacZ-RLX, compared with parental virus or vehicle, elicited higher transduction efficiency and viral spread throughout the tumor mass. Infection with Ad-deltaE1B-RLX, compared with parental virus, elicited greater viral persistence and spread, leading to increased survival (e.g., 100%, 95% confidence interval [CI] = 63.1% to 100%, for C33A tumor-bearing mice treated with Ad-deltaE1B-RLX, and 50%, 95% CI = 15.7% to 84.3%, for C33A tumor-bearing mice treated with Ad-deltaE1B). Infection with Ad-deltaE1B-RLX substantially decreased the collagen content of tumor tissue but not of adjacent normal tissue, compared with noninfected tissues. Intratumoral injection of Ad-deltaE1B-RLX inhibited the formation of lung metastases in mice (PBS = 268 mg of metastatic tumor per mouse and Ad-deltaE1B-RLX = 10 mg; difference = 258 mg, 95% CI = 94 to 426; P = .003, Mann-Whitney test). Systemic treatment with Ad-deltaE1B-RLX completely inhibited the growth of Hep1 hepatocellular carcinomas (PBS = 20.2 mg of tumor per mouse and Ad-deltaE1B-RLX = 0 mg; difference = 20.2 mg, 95% CI = 3.7 to 36.7; P = .004, Mann-Whitney test).
Conclusion:
Extracellular matrix degradation by relaxin expressed by adenoviruses increased viral distribution and tumor penetration, inhibited tumor growth and metastasis, and increased survival of mice.
Insights
Engineered adenoviruses expressing relaxin improved tumor penetration and distribution. This enhanced oncolytic virus therapy led to significant tumor growth inhibition, reduced metastasis, and increased survival rates in preclinical models.
Area of Science:
- Oncolytic virotherapy
- Cancer gene therapy
- Tumor microenvironment modulation
Background:
- Oncolytic adenoviruses face challenges with tumor penetration and distribution, limiting their efficacy in cancer gene therapy.
- Investigating methods to improve adenovirus delivery and spread within solid tumors is crucial for enhancing therapeutic outcomes.
Purpose of the Study:
- To evaluate if expressing the matrix-degradative protein relaxin via adenovirus can enhance viral distribution and penetration in tumors.
- To assess the therapeutic potential of relaxin-expressing adenoviruses in preclinical cancer models.
Main Methods:
- Generated replication-incompetent and competent adenoviruses engineered to express relaxin.
- Assessed viral spread and transduction efficiency in tumor spheroids and xenograft models.
- Evaluated tumor growth inhibition, metastasis, and overall survival in mouse models, alongside extracellular matrix analysis.
Main Results:
- Relaxin-expressing adenoviruses demonstrated superior transduction efficiency and viral spread within tumors compared to controls.
- Infection with relaxin-expressing adenoviruses led to increased viral persistence, enhanced survival rates, and significant reduction in tumor collagen content.
- Therapeutic efficacy was observed through inhibited lung metastasis and complete inhibition of hepatocellular carcinoma growth in vivo.
Conclusions:
- Adenovirus-mediated expression of relaxin effectively degrades the extracellular matrix, improving viral distribution and tumor penetration.
- This approach significantly inhibits tumor growth and metastasis, leading to increased survival in preclinical models.
- Relaxin-engineered adenoviruses represent a promising strategy for enhancing oncolytic virotherapy effectiveness.
