C1qc, a polypeptide in the serum complement system, is a key component of the classical complement pathway. The classical complement pathway is crucial for the immune response, participating in processes like opsonization, cell lysis, and inflammation regulation, thus having significant biological importance in the body's defense mechanisms [3].

In various diseases, C1qc shows diverse roles. In kidney renal clear cell carcinoma (KIRC), C1qc expression is upregulated in tumor tissues compared to adjacent normal tissues. Knockdown of C1qc in vitro inhibits KIRC cell proliferation, migration, and invasion, indicating its tumor-promoting role. It is also associated with clinicopathological features and prognosis in KIRC, and is involved in immune-related biological processes [1]. In colon carcinoma, single-cell analysis suggests that C1qc may be a critical regulatory factor in the occurrence and progression of the disease, being highly expressed in colon cancer tissue, and its high expression is related to a worse prognosis [2]. In diffuse large B-cell lymphoma (DLBCL), single-cell sequencing shows high C1qc expression in M2 macrophages. Knocking down C1qc reduces the expression of CD163 in M2 macrophages, and M2 macrophages can promote tumor cell proliferation and reduce drug sensitivity. High expression of C1qC + M2 macrophages is associated with poor prognosis in DLBCL patients [3].

In conclusion, C1qc is essential in the immune-related functions through its role in the complement system. Its dysregulation is implicated in multiple cancer types including KIRC, colon carcinoma, and DLBCL. The findings from gene-knockdown experiments in these disease models have revealed its tumor-promoting properties, highlighting its potential as a prognostic biomarker and therapeutic target in these cancers [1,2,3].

References:

1. Yao, Wentao, Liu, Hanyuan, Xu, Feng, Yang, Chendi, Zong, Yang. 2023. C1QC is a prognostic biomarker with immune-related value in kidney renal clear cell carcinoma. In Frontiers in genetics, 14, 1109991. doi:10.3389/fgene.2023.1109991. https://pubmed.ncbi.nlm.nih.gov/36992705/

2. Deng, Huiming, Chen, Yan, Liu, Yong, Liu, Li, Xu, Ronghua. 2022. Complement C1QC as a potential prognostic marker and therapeutic target in colon carcinoma based on single-cell RNA sequencing and immunohistochemical analysis. In Bosnian journal of basic medical sciences, 22, 912-922. doi:10.17305/bjbms.2022.7309. https://pubmed.ncbi.nlm.nih.gov/35765947/

3. Gao, Guangcan, Sun, Naitong, Zhang, Yaping, Tang, Yunlong, Shi, Wenyu. 2024. Single-cell sequencing in diffuse large B-cell lymphoma: C1qC is a potential tumor-promoting factor. In International immunopharmacology, 143, 113319. doi:10.1016/j.intimp.2024.113319. https://pubmed.ncbi.nlm.nih.gov/39388888/