Triple negative (TN) (
estrogen receptor [ER],
progesterone receptor [PR] and HER2-) are highly aggressive, rapidly growing,
hormone-unresponsive
tumors diagnosed at later stage that affect younger women with shorter overall survival. Most TN
tumors are of the basal type. For the remainder, identification of target markers for effective treatment strategies remains a challenge.
Transgelin (TGLN) is a 22-kd
actin-binding protein of the
calponin family. It is one of the earliest markers of smooth muscle differentiation. TGLN has been shown to have important
biologic activities including regulating muscle fiber contractility, cell migration, and
tumor suppression. We examined TGLN expression in the different molecular subtypes of
breast cancer. TGLN expression was examined as a function of
tumor size, grade, histologic type, lymph node status, patients' age and overall survival, ER, PR, HER2, and Ki-67 in 101
tumors that included 35
luminal A, 28
luminal B, 4 HER2, and 34 TN types. TGLN positivity (defined as 2+ or 3+) was associated with more aggressive
tumors (10% of grade I/II
tumors were TGLN+ versus 53% of grade III
tumors; P < .001), high Ki-67 count, and low ER and PR expression (P < .001) but not with
tumor size, age, or
lymph node metastasis. TN (n = 34)
tumors were 7.7 times more likely to be TGLN+ than non-TN (n = 67)
tumors (77% versus 10%, respectively; P < .001). TGLN may be an excellent diagnostic marker of TN
tumors and could be useful in stratification of patients. TGLN may also prove a potential target for future treatment strategies.