Long non-coding RNA XIST: a novel oncogene in multiple cancers

Long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) is an important lncRNA derived from the XIST gene in mammals. XIST is abnormally expressed in numerous tumors, in most of which XIST functions as an oncogene. XIST is involved in multiple aspects of carcinogenesis, including tumor onset, progression, and prognosis. In our review, we collected and analyzed the recent studies on the impact of XIST in human tumor development. The multilevel molecular functions of XIST in human tumors are comprehensively reviewed to clarify the pathologic mechanisms and to offer a novel direction for further study.

Effect of Non-Coding Region RNA Gene XIST (X-Inactive Specific Transcript) on Human Breast Cancer

X chromosome is a sex chromosome found in both women and men. The inactivation of the X chromosome is linked to a non-coding region of RNA known as the XIST gene (X-inactive specific transcript). This gene is located in the X inactivation center (XIC X-inactive center). The XIST gene is a region that belongs to the RNA group, non-coding transcripts (NCT), also known as microRNA. Breast cancer (Breast Cancer) is a type of cancer that commonly affects women, but men can develop breast cancer, but the chances are small, about 1 in 1000. Breast cancer is a cancerous neoplasm that is malignant, and occurs in the mammary gland. The presence of a specific XIST gene on the X chromosome and the prevalence of breast cancer, which is mostly in women, raises the idea that there is an influence of this gene on breast cancer (breast cancer) in the epigenetic process. The XIST gene related to microRNA has an opportunity to be looked at because certain microRNAs have a greater or lesser level (concentration) in cancer cells than normal cells. This is a new opportunity to continue to be developed as a consideration for a new treatment method involving gene therapy.

Complex sSMC Involving X and Y Chromosomes in two Patients with 45,X/46,X,+mar Karyotype

Complex small supernumerary marker chromosomes (sSMCs) consist of chromosomal material derived from two or more different chromosomal regions and constitute one of the smallest subsets of sSMC. Most of complex sSMCs are represented by a der(22)t(11;22) in Emanuel syndrome. As far as we know, only one recent report has described sSMCs involving simultaneously X and Y chromosomes in Turner Syndrome. We report two patients, a female and a male, both with a complex sSMC derived from X and Y chromosomes in mosaic with a 45,X cell line. In both patients, the marker chromosomes were early replicating and the XIST gene was absent. FISH and PCR confirmed the presence of Yp loci (TSPY, AMGY, SRY, DYZ3), and negative for DYZ1. The DAZ4 sequence was present only in patient 1.Our findings suggested that complex sSMC involving X and Y chromosome could be a kind of sSMC of the gonosomes.

A Rare Combination of Functional Disomy Xp, Deletion Xq13.2-q28 Spanning the XIST Gene, and Duplication 3q25.33-q29 in a Female with der(X)t(X;3)(q13.2;q25.33)

We report a 19-year-old female patient with a history of short stature, primary ovarian insufficiency, sensorineural hearing loss, sacral teratoma, neurogenic bladder, and intellectual disability with underlying mosaicism for der(X)t(X;3)(q13.2;q25.33), a ring X chromosome, and monosomy X. Derivative X chromosomes from unbalanced X-autosomal translocations are preferentially silenced by the XIST gene (Xq13.2) located within the X-inactivation center. The unbalanced X-autosomal translocation in our case resulted in loss of the XIST gene thus precluding the inactivation of the derivative X chromosome. As a result, clinical features of functional disomy Xp, Turner's syndrome, and duplication 3q syndrome were observed. Importantly, indications of the derivative X chromosome were revealed by microarray analysis following an initial diagnosis of Turner's syndrome made by conventional cytogenetic studies approximately 18 months earlier. This case demonstrates the importance of utilizing microarray analysis as a first-line test in patients with clinical features beyond the scope of a well-defined genetic syndrome.