Relationships of hHpr1/p84/Thoc1 expression to clinicopathologic characteristics and prognosis in non-small cell lung cancer.

Nuclear matrix proteins (NMPs) are important diagnostic and prognostic markers in various human cancers. The hHpr1/p84/Thoc1 protein, a key NMP, resides in the nuclear matrix and is involved in the human TREX complex, which is required for regulation of transcription elongation, pre-RNA splicing, and mRNA export of a subset of human genes. Depletion of hHpr1/p84/Thoc1 decreases growth rates in multiple cancer cell lines, and the expression levels of hHpr1/p84/Thoc1 are strongly associated with tumor size and aggressiveness of several human cancers. Little is known about the expression of this protein in human non-small cell lung cancer (NSCLC) and its association with patients' clinicopathologic characteristics and prognosis. We evaluated hHpr1/p84/Thoc1 expression in 133 NSCLC patients by immunohistochemistry of tissue microarrays using paraffin-embedded tumor tissue and we confirmed the tissue staining by Western blot analysis. The prognostic significance of hHpr1/p84/Thoc1 expression in tumor tissue was assessed by the Cox proportional hazards regression model. hHpr1/p84/Thoc1 expression was found in 51% of patients, and was more prevalent in males than females (59% vs 43%, p = 0.07) and in blacks than whites (91% vs 48%, p = 0.009). In survival analysis, hHpr1/p84/Thoc1 expression appeared to be weakly associated with elevated risk of death among patients with stage I tumors (RR = 1.53, 95% CI = 0.85-2.77, p = 0.16), squamous cell carcinomas (RR = 1.75, 95% CI = 0.73-4.21, p = 0.21), and family histories of lung cancer (RR = 1.55, 95% CI = 0.81-2.97, p=0.18), although none of these associations was statistically significant. Thus elevated expression of hHpr1/p84/Thoc1 is common in NSCLC and may have prognostic significance in subgroups of patients. Further studies with larger sample size are needed to elucidate the role of this critical nuclear matrix protein in NSCLC prognosis.