The Study of the Expression of CGB1 and CGB2 in Human Cancer Tissues

Abstract

Human chorionic gonadotropin (hCG) is a well-known hormone produced by the trophoblast during pregnancy as well as by both trophoblastic and non-trophoblastic tumors. hCG is built from two subunits: α (hCGα) and β (hCGβ). The hormone-specific β subunit is encoded by six allelic genes: CGB3, CGB5, CGB6, CGB7, CGB8, and CGB9, mapped to the 19q13.32 locus. This gene cluster also encompasses the CGB1 and CGB2 genes, which were originally considered to be pseudogenes, but as documented by several studies are transcriptionally active. Even though the protein products of these genes have not yet been identified, based on The Cancer Genome Atlas (TCGA) database analysis we showed that the mutual presence of CGB1 and CGB2 transcripts is a characteristic feature of cancers of different origin, including bladder urothelial carcinoma, cervical squamous cell carcinoma, esophageal carcinoma, head and neck squamous cell carcinoma, ovarian serous cystadenocarcinoma, lung squamous cell carcinoma, pancreatic adenocarcinoma, rectum adenocacinoma, testis germ cell tumors, thymoma, uterine corpus endometrial carcinoma and uterine carcinosarcoma.

Keywords: CGB1; CGB2; TCGA; cancer; human chorionic gonadotropin.

Figure 1

Expression level of CGB1 in cancer, according to The Cancer Genome Atlas (TCGA) data; TPM—transcripts per million; ACC—Adrenocortical carcinoma; BLCA—Bladder urothelial carcinoma; BRCA—Breast invasive carcinoma; CESC—Cervical squamous cell carcinoma; CHOL—Cholangiocarcinoma; COAD—Colon adenocarcinoma; DLBC—Lymphiod neoplasm diffuse large B-cell lymphoma; ESCA—Esophageal carcinoma; GBM—Glioblastoma multiforme; HNSC—Head and Neck squamous cell carcinoma; KICH—Kidney chromophobe; KIRC—Kidney renal clear cell carcinoma; KIRP—Kidney renal papillary cell carcinoma; LGG—Brain lower grade glioma; OV—Ovarian serous cystadenocarcinoma; MESO—Mesothelioma; LIHC—Liver hepatocellular carcinoma; LUAD—Lung adenocarcinoma; LUSC—Lung squamous cell carcinoma; PAAD—Pancreatic adenocarcinoma; PRAD—Prostate adenocarcinoma; PCPG—Pheochromocytoma and Paraganglioma; READ—Rectum adenocacinoma; SARC—Sarcoma; SKCM—Skin cutaneous melanoma; LAML—Acute Myeloid Leukemia; TGCT—Testis germ cell tumors; THCA—Thyroid carcinoma; THYM—Thymoma; STAD—Stomach adenocarcinomna; UCEC—Uterine corpus endometrial carcinoma; USC—Uterine carcinosarcoma; UVM—Uveal Melanoma.

Figure 2

Expression of CGB2 in cancer, according to TCGA data.

Figure 3

Expression levels of CGB1 and CGB2 in primary tumor samples and corresponding healthy tissues according to data deposited in the UALCAN database. (A) Expression of CGB2 in BLCA, (B) expression of CGB2 in ESCA, (C) expression of CGB2 in HNSC, (D) expression of CGB2 in LUSC, (E) expression of CGB2 in UCEC, (F) expression of CGB1 in UCEC. ** p ≤ 0.01; *** p ≤ 0.001.