The SSX Family of Cancer-Testis Antigens as Target Proteins for Tumor Therapy

Table 1

SSX family members: expression, fusion constructs, inducibility, and isoforms. The mRNA expression patterns of the ten known SSX family members are shown for testis and tumor tissues in columns 2, 3, and 4, while SSX family members known to be involved in the SS18-SSX fusion event are shown in column 5. SSX members shown to be inducible with epigenetic modifying agents or known to have alternative splice isoforms are shown in columns 6 and 7, respectively. References are given in column 8.

	Transcribed	Expressed in testis	Expressed in cancer	Fusion partner with SS18	Inducible	Alternative splices	Reference
SSX1	+	+	+	+	+		[27]
SSX2	+	+	+	+	+	+	[27, 74]
SSX3	+	+	−*		−		[27]
SSX4	+	+	+	+**	+	+	[27]
SSX5	+	+	+/−		+	+	[27]
SSX6	+	−	−*		+/−		[29]
SSX7	+	+	−*		−	+	[29]
SSX8	+	+	−		−		[29, 73]
SSX9	+	+	−		−		[29, 73]
SSX10	+	n.d	n.d	n.d.	n.d.	n.d.	—

+ = positive/strong, +/− = positive/weak, − = negative/undetectable.
*very seldom.
**Only one case observed [75].
n.d. = not demonstrated.