Nicotinamide N-methyltransferase (NNMT) is overexpressed in many human cancers and is associated with poor prognosis. Akt (also known as protein kinase B) is an evolutionarily conserved serine/threonine kinase, serving as a downstream effector of the phosphatidylinositol 3-kinase signaling pathway. NNMT was first identified as a differentially upregulated gene in nasopharyngeal cancer tissues through data mining from published transcriptomic databases. Since no prior study has attempted to evaluate the clinical significance of NNMT or phosphorylated Akt (pAkt) expression in nasopharyngeal cancer, this study explores their expression in a large cohort of patients with nasopharyngeal cancer. The study included 124 nasopharyngeal cancer patients who were free of distant metastasis at initial diagnosis. Pathological slides were reviewed and clinical findings collected. We evaluated the expression of NNMT and pAkt immunohistochemically, stratified them into two groups (high and low expression) and examined the correlation with disease-specific survival (DSS), metastasis-free survival (MeFS), local recurrence-free survival (LRFS), and various clinicopathological factors. NNMT expression was significantly positively associated with pAkt expression. The high expression of both markers was significantly associated with an increment of tumor stage (p = 0.006 and p = 0.006, respectively). High expression of NNMT correlated significantly with a more aggressive clinical course and a significantly shorter DSS. Furthermore, NNMT expression and pAkt expression were strongly predictive of MeFS (p = 0.008; p = 0.0063) and LRFS (p = 0.005; p = 0.0125). In multivariate analysis, high expression of NNMT remained as a robust prognosticator for both end points evaluated. It independently portended inferior DSS (p = 0.02, HR = 1.976) and worse MeFS (p = 0.029, HR = 2.022) after tumor stage (p = 0.033, HR = 2.150; p = 0.028, HR = 2.942, for DSS and LRFS, respectively). We found NNMT positively correlated with pAkt expression and was independent adverse prognosticators of patient survival. NNMT therefore has potential utility as an indicator for prognosis, predicting treatment response to chemotherapy or radiation therapy, and even as a therapeutic target in the future.

Fatty acid synthase (FASN) is overexpressed in many human cancers and associated with poor prognosis. However, the role of FASN in nasopharyngeal carcinoma (NPC) has not been studied. We evaluated the expression of FASN immunohistochemically in 124 NPC specimens, stratified them into two groups (FASN-high and FASN-low), and examined the correlation with various clinicopathological parameters. In two NPC cell lines, HONE1 and TW01, we targeted the FASN transcript by shRNAi and evaluated the effect on cell proliferation by WST-1 assay and radiation-induced apoptosis by measuring caspase-3 and caspase-7 activation. NPC with high FASN immunoexpression was correlated with advanced pT disease status and worse prognosis in terms of disease-specific survival, metastasis-free survival and local recurrence-free survival, compared to FASN-low group in both univariate and multivariate analyses. In the two NPC cell lines, endogenous FASN expression was significantly higher than the non-tumor keratinocyte, DOK. When the expression of FASN was suppressed by shRNAi, the tumor cells showed decreased cell proliferation and increased apoptosis after radiation. Our results supported FASN as an adverse prognostic marker in NPC, possibly by conferring cell growth advantage and resistance to radiation-induced apoptosis on tumor cells. The inhibition of FASN expression might be investigated as an adjunct in treatment, especially in radiation resistant NPC.

No abstract

Locally advanced rectal cancers are currently treated with neoadjuvant concurrent chemoradiotherapy (CCRT) followed by surgery, but stratification of risk and final outcomes remain suboptimal. In view of the fact that glutamine metabolism is usually altered in cancer, we profiled and validated the significance of genes involved in this pathway in rectal cancers treated with CCRT. From a published transcriptome of rectal cancers (GSE35452), we focused on glutamine metabolic process-related genes (GO:0006541) and found upregulation of carbamoyl phosphate synthetase 1 (CPS1) gene most significantly predicted poor response to CCRT. We evaluated the expression levels of CPS1 using immunohistochemistry to analyze tumor specimens obtained during colonoscopy from 172 rectal cancer patients. Expression levels of CPS1 were further correlated with major clinicopathological features and survivals in this validation cohort. To further confirm CPS1 expression levels, Western blotting was performed for human colon epithelial primary cell (HCoEpiC) and four human colon cancer cells, including HT29, SW480, LoVo, and SW620. CPS1 overexpression was significantly related to advanced posttreatment tumor (T3, T4; P = 0.006) and nodal status (N1, N2; P < 0.001), and inferior tumor regression grade (P = 0.004). In survival analyses, CPS1 overexpression was significantly associated with shorter disease-specific survival (DSS) and metastasis-free survival (MeFS). Furthermore, using multivariate analysis, it was also independently predictive of worse DSS (P = 0.021, hazard ratio = 2.762) and MeFS (P = 0.004, hazard ratio = 3.897). CPS1 protein expression, as detected by Western blotting, is more abundant in colon cancer cells than nonneoplastic HCoEpiC. Overexpression of CPS1 is associated with poor therapeutic response and adverse outcomes among rectal cancer patients receiving CCRT, justifying the potential theranostic value of CPS1 for such patients.

The S-phase kinase-associated protein 2 (SKP2) oncoprotein is an E3 ubiquitin ligase. Overexpression of SKP2 was found in various human cancers, including colorectal cancers, but its potential role as a prognostic marker after neoadjuvant chemoradiotherapy (CRT) and for therapeutic intervention in rectal cancers is unknown. This study examined the correlation of SKP2 expression in the prognosis of rectal cancer patients and the viability of colorectal cancer cells treated with CRT. SKP2 immunoexpression was retrospectively assessed in pretreatment biopsies of 172 rectal cancer patients treated with neoadjuvant CRT followed by surgery. Results were correlated with clinicopathological features, therapeutic responses, and patient survival. Pharmacologic assays were used to evaluate the therapeutic relevance of Bortezomib in two colorectal cancer cell lines (HT-29 and SW480). High expression of SKP2 was correlated with the advanced Post-Tx nodal status (p = 0.002), Post-Tx International Union for Cancer Control stage (p = 0.002), and a lower-degree tumor regression grade (p < 0.001). Moreover, high expression of SKP2 (p = 0.027, hazard ratio 3.21) was an independent prognostic factor for local recurrence-free survival. In vitro, Bortezomib downregulated SKP2 expression, induced caspase activation, and decreased the viability of colorectal cancer cells with or without a combination with fluorouracil. Bortezomib also promoted caspase activation and gamma-H2AX formation in colorectal cancer cells concurrently treated with CRT. High expression of SKP2 was associated with a poor therapeutic response and adverse outcomes in rectal cancer patients treated with neoadjuvant CRT. In the presence of chemotherapy with or without radiotherapy, the promoted sensitivity of colorectal cancer cells to Bortezomib with an SKP2-repressing effect indicated that it is a potential therapeutic target.