Table 1.

Putative X-linked tumor suppressor genes in human cancers

Gene	Locus	X-linked in other mammals	Function	Signaling pathway	Involvement in cancer
FOXP3	Xp11.23	Mouse, Rat, Dog	Transcriptional factor; Master regulator in the development and function of regulatory T cells; Tumor suppressor	Nuclear transcritional regulation of the HER2, SKP2, c-Myc and p21	Down-regulated in breast cancer, prostate cancer and ovarain cancer tissues, but overexpression in pancreatic cancer tissues; Gene deletions and somatic mutations identified in breast cancer and prostate cancer
RBBP7	Xp22.2	Mouse, Rat, Dog	Putative tumor suppressor involved in cell proliferation, differentiation and apoptosis	Regulation of the Rb, BRCA1, WT1 and beta- catenin/TCF signalings	Unknown
CD99	Xp22.32 and Yp11.3	Dog, but not in Mouse, Rat	cell-cell adhesion; Leukocyte migration, T- cell adhesion, ganglioside GM1 and transmembrane protein transport, and T-cell death and involved in in tumor malignancy and metastases	Caspase- independent pathway and AKT-, ERK-, and JNK- dependent AP-1 activation signaling pathways	Down-regulation in osteosarcoma, gallbladder carcinomas, nasopharyngeal carcinoma, gastric adenocarcinoma, and transitional cell carcinomas of urinary bladder, but up- regulated in desmoplastic small-cell tumours, synovial sarcomas, primitive neuroectodermal tumours and hepatocarcinomas; LOH at this locus and promoter methylation identified in gastric adenocarcinoma
FAM123B	Xq11.1	Mouse, Rat, Dog	Tumor suppressor for Wilms tumor	Inhibition of the beta- catenin signaling and modulation of WT1 activity	Gene deletion and somatic mutation identified in Wilms tumors
EDA2R	Xq12	Mouse, Rat, but unknow in Dog	Promoting apoptosis in tumor cells and epidermal morphogenesis during embryonic development	Activation of the NF- kappaB and JNK pathways; downstream target of p53	Down-regulated in breast cancer and colorectal cancer; mutation and hypermethylation identified in colorectal cancer
RPS6KA6	Xq21	Mouse, Rat, Dog	Inducing cell arrest and senescence and involved in invasion and chemotaxis	Up-regulation of Rb, retinobl astoma- associated 46 kDa protein, p21, and claudin-2, but down- regulation of CXCR4	Down-regulated in colon carcinomas, colon adenomas, renal cell carcinomas, and endometrial cancers
ATRX	Xq21.1	Mouse, Rat, Dog	Nevol tumor suppressor involved in transcriptional regulation, nuclear architecture, and chromosome stability	Regulation of chromatin remodeling, DNA methylation and gene transcription	Down-regulation in acute myeloid leukemia, prostate cancer, breast cancer, esophageal squamous cell carcinoma; loss-of- function somatic mutations in pancreatic neuroendocrine tumor and paediatric glioblastoma
ELF4	Xq26.1	Mouse, Rat, Dog	Transcriptional regulation, DNA damage response, and involved in natural killer (NK) cell development and function	Transcriptional activation of the CSF2, IL3, IL8, and PRF1 and repression of MMP-9 and IL-8	LOH at this locus identified in ovarian and breast cancers; translocation in acute myelogenous leukemia; rearrangements of BCORL1-ELF4 in hepatocellular carcinomas
PHF6	Xq26.3	Mouse, Dog, but unknow in Rat	Transcriptional regulation	Regulation of homeobox transcription factor oncogenes TLX1 and TLX3	Mutation and deletion frequently found in T- cell acute lymphoblastic leukemia, adult acute myeloid leukemia, and hepatocellular carcinoma
LDOC1	Xq27	Mouse, Rat, Dog	Inducing apoptosis in tumor cells	Inhibition of the NF- kappaB signaling and the degradation of p53	Down-regulated in pancreatic and gastric cancer cell lines; deletions identified in prostate cancers, but high levels of LDOC1 correlate with poor prognosis in chronic lymphocytic leukemia
RPL10	Xq28	Mouse, Rat, Dog	Putative tumor suppressor for hormonally dependent cancers	Repression of the c-Jun and AP-1- mediated transcriptional activation	LOH and microsatellite instability at this locus frequently occurred in ovarian cancer; down- regulated in prostate cancer and multiple endocrine neoplasia type 1
DKC1	Xq28	Mouse, Rat, Dog	Multiple functions in telomerase, ageing and cancerr	RNA processing and modification; p53- and p27- denpendent translational control in ribosome biogenesis	Unknown