Will Exosome Be the New Star in Treating Renal Cancer

Renal cell carcinoma (RCC), referred to as renal cancer, accounts for 3% of adult malignancies. It is one of the common malignant tumors of the urinary system and the incidence has been increasing year by year. Early renal cancer patients have no obvious symptoms, while the diagnosis is mainly based on imaging examinations. More than 16% of patients have already shown distant metastases when they receive the first diagnosis.

Surgical resection is currently considered to be the only effective cure for RCC. However, more than 20% of patients will experience local recurrence or distant metastasis after surgery. Most renal cancers are not sensitive to chemotherapy and radiotherapy once recurrence or metastasis occurs, and molecular targeted drug treatment is prone to drug resistance, with the 5-year survival rate less than 40%.

Therefore, how to detect kidney cancer early, effectively predict the risk of tumor metastasis, and discover new drug targets has always been the focus and difficulty of kidney cancer research.

In 1983, Johnstone first discovered exosomes in reticulocyte culture fluid, which are a class of extracellular vesicles with a diameter of 30 to 100 nm and a lipid bilayer membrane structure. They are widely found in various body fluids such as peripheral blood, urine, and ascites, carrying a variety of signal molecules and biologically active substances, and participating in a variety of biological processes such as body immunity, intercellular communication, tumorigenesis and development, etc. In recent years, exosome therapy in urinary tumor diseases has become a research focus such as prostate cancer and bladder cancer.

The diagnosis of renal cancer relies on imaging examinations such as ultrasound and CT, and lacks effective serological markers. Therefore, many patients with renal cancer have metastasized at the time of diagnosis and have a poor prognosis. Exosomes have specificity related to cell origin and can be extracted from body fluids. Therefore, many scholars at home and abroad believe that exosomes may be used as biomarkers for the diagnosis of renal cancer.

At present, many studies have found significant differences in the expression of specific components of exosomes between renal cancer patients and normal people, suggesting that exosomes may be used as serological markers for early diagnosis and prognostic evaluation of renal cancer.

"However, these studies are mostly retrospective studies with limited number of included samples and pathological types, and the sensitivity and specificity of the research are not yet convincing." Said a scientist in Creative Biolabs, a first-class biotech manufacturer providing exosome related services, "so a more comprehensive study is expected to unveil the secret of exosome in renal cancer."

In clinical treatment, many patients with kidney cancer are sensitive to targeted drug treatment, but afterwards there will be varying degrees of drug resistance. However, the mechanism of drug resistance in kidney cancer is complex and unclear. It’s known that tumor cells can excrete chemotherapeutic drugs through exosomes, while miRNAs, resistance-related proteins and other substances are transported through exosomes to mediate drug resistance transmission, so that non-resistant tumor cell subpopulations acquire resistance. Studies have shown that exosomes help to present tumor-specific antigens, have the potential to promote active and passive immunity, which provides a new biological approach to the treatment of renal cancer.

Exosomes secreted by renal cancer cells are widely present in body fluids such as blood and urine of patients. They not only have the advantages of availability of sources, non-invasive examination, specificity of tumors, but also can easily penetrate the biofilm, and well protect the rich bioactive substances from degradation for their small size, strong mobility, and natural lipid bilayers.

Current exosome research has found that exosomes have obvious expression differences between renal cancer patients and normal subjects, and play an important role in the invasion and metastasis. They also participate in tumor resistance and immune escape and other processes. Related results provide new ideas for the diagnosis and treatment of renal cancer patients.

However, there is still a long way to go in the field of exosomes-mediated resistance and effects of targeted drug resistance in renal cancer treatment. Scientists are trying to find how exosomes can solve the problem of drug resistance and there will be more and more targeted drugs for renal cancer in the future.

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