The Relative Expression of Mig6 and EGFR Is Associated with Resistance to EGFR Kinase Inhibitors

The sensitivity of only a few tumors to anti-epidermal growth factor receptor EGFR tyrosine kinase inhibitors (TKIs) can be explained by the presence of EGFR tyrosine kinase (TK) domain mutations. In addition, such mutations were rarely found in tumor types other than lung, such as pancreatic and head and neck cancer. In this study we sought to elucidate mechanisms of resistance to EGFR-targeted therapies in tumors that do not harbor TK sensitizing mutations in order to identify markers capable of guiding the decision to incorporate these drugs into chemotherapeutic regimens. Here we show that EGFR activity was markedly decreased during the evolution of resistance to the EGFR tyrosine kinase inhibitor (TKI) erlotinib, with a concomitant increase of mitogen-inducible gene 6 (Mig6), a negative regulator of EGFR through the upregulation of the PI3K-AKT pathway. EGFR activity, which was more accurately predicted by the ratio of Mig6/EGFR, highly correlated with erlotinib sensitivity in panels of cancer cell lines of different tissue origins. Blinded testing and analysis in a prospectively followed cohort of lung cancer patients treated with gefitinib alone demonstrated higher response rates and a marked increased in progression free survival for patients with a low Mig6/EGFR ratio (approximately 100 days, P = 0.01).     

Decreased Expression of AZGP1 Is Associated with Poor Prognosis in Primary Gastric Cancer

Background

2-Zinc-glycoprotein 1 (AZGP1) is a multidisciplinary protein that participates in many important functions in the human body, including fertilization, immunoregulation and lipid mobilization. Recently, it has been shown that AZGP1 is also involved in carcinogenesis and tumor differentiation. In this study, we investigated the expression levels and prognostic value of AZGP1 in primary gastric cancers.

Methods and Results

We examined the expression of AZGP1 in 35 paired cancerous and matched adjacent noncancerous gastric mucosa tissues by real-time quantitative RT-PCR (qRT-PCR) and western blotting. Furthermore, we analyzed AZGP1 expression in 248 patients who underwent resection procedures between 2005 and 2007 using immunohistochemistry. The relationships between the AZGP1 expression levels, the clinicopathological factors, and patient survival were investigated. AZGP1 expression was significantly reduced at both the mRNA (P = 0.023) and protein levels (P = 0.019) in tumor tissue samples, compared with expression in matched adjacent non-tumor tissue samples. The immunohistochemical staining data showed that AZGP1 expression was significantly decreased in 52.8% (131/248) of gastric adenocarcinoma cases. Clinicopathological analysis showed that the reduced expression of AZGP1 was significantly correlated with tumor location (P = 0.011), histological grade (P = 0.005) and T stage (P = 0.008). Kaplan–Meier survival curves revealed that the reduced expression of AZGP1 was associated with a poor prognosis in gastric adenocarcinoma patients (P = 0.009). Multivariate Cox analysis identified AZGP1 expression was an independent prognostic factor for overall survival of gastric adenocarcinoma patients (HR = 1.681, 95% CI = 1.134–2.494, P = 0.011).

Conclusions

Our study suggests that AZGP1 might serve as a candidate tumor suppressor and a potential prognostic biomarker in gastric carcinogenesis.     

Increased Expression of Pregnancy Up-Regulated Non-Ubiquitous Calmodulin Kinase Is Associated with Poor Prognosis in Clear Cell Renal Cell Carcinoma

Purpose

The aims of this study were to evaluate the clinical significance and potential prognostic value of pregnancy up-regulated non-ubiquitous calmodulin kinase (PNCK) in clear cell renal cell carcinoma (ccRCC) patients.

Materials and Methods

The expression of PNCK mRNA was determined in 24 paired samples of ccRCCs and adjacent normal tissues using real-time RT-PCR. The expression of PNCK was determined in 248 samples of ccRCCs and 92 paired samples of adjacent normal tissues by immunohistochemical analysis. Statistical analysis was performed to define the relationship between PNCK expression and the clinical features of ccRCC.

Results

The mRNA level of PNCK was significantly higher in tumorous tissues than in the adjacent non-tumorous tissues (p<0.001). An immunohistochemical analysis of 92 paired tissue specimens showed that PNCK expression was higher in tumorous tissues than in the adjacent non-tumorous tissues (p<0.001). Moreover, there was a significant correlation between the PNCK expression and various clinicopathological parameters such as Fuhrman grade (p = 0.011), tumor size (p<0.001), T stage (p<0.001) and N stage (p = 0.015). Patients with higher PNCK expression had shorter overall survival time than those with lower PNCK expression (p<0.001). Multivariate analysis indicated that PNCK expression was an independent predictor for poor survival of ccRCC patients.

Conclusions

To our knowledge, this is the first study that determines the relationship between PNCK and prognosis in ccRCC. We found that increased PNCK expression is associated with poor prognosis in ccRCC. PNCK may represent a novel prognostic marker for ccRCC.     

High Progesterone Receptor Expression in Prostate Cancer Is Associated with Clinical Failure

BackgroundProstate cancer is a highly heterogeneous disease and one of the leading causes of mortality in developed countries. Specific prognostic and predictive markers for prostate cancer patients are still lacking. A causal relationship between androgens and the development of prostate cancer is generally considered biologically plausible, but androgens are not the sole effector in the complexity of prostate carcinogenesis. The aim of this study was to evaluate the prognostic significance of progesterone receptor in tumor tissue of T1-3N0 prostate cancer patients undergoing prostatectomy.MethodsTissue microarrays from 535 patients with prostate cancer were constructed. Duplicate cores of tumor cells and tumor stromal tissue from each resected specimen were extracted. Immunohistochemistry was used to evaluate the in-situ expression of progesterone receptor.ResultsIn univariate analyses, high tumor cell density (p = 0.006) and high tumor stromal cell density level (p = 0.045) of progesterone receptor were both significantly associated with tumor progression and clinical failure. In multivariate analysis, progesterone receptor expression in tumor cells was an independent negative prognostic factor for clinical failure (HR: 2.5, 95% CI: 1.2–5.2, p = 0.012).ConclusionHigh progesterone receptor density in tumor cells of the prostate cancer tumor is an independent negative prognostic factor for clinical failure.     

Expression of Sirtuin 1 and 2 Is Associated with Poor Prognosis in Non-Small Cell Lung Cancer Patients

Background

Sirtuin 1 (SIRT1) and sirtuin 2 (SIRT2) are NAD+-dependent protein deacetylases involved in the regulation of key cancer-associated genes. In this study we evaluated the relevance of these deacetylases in lung cancer biology.

Material and Methods

Protein levels of SIRT1 and SIRT2 were determined in non-small cell lung cancer (NSCLC) cell lines and primary tumors from 105 patients. Changes in proliferation were assessed after SIRT1 and SIRT2 downregulation in lung cancer cell lines using siRNA-mediated technology or tenovin-1, a SIRT1 and SIRT2 inhibitor.

Results

High SIRT1 and SIRT2 protein levels were found in NSCLC cell lines compared with non-tumor lung epithelial cells. The expression of SIRT1 and SIRT2 proteins was also significantly higher in lung primary tumors than in normal tissue (P<0.001 for both sirtuins). Stronger nuclear SIRT1 staining was observed in adenocarcinomas than in squamous cell carcinomas (P=0.033). Interestingly, in NSCLC patients, high SIRT1 and SIRT2 expression levels were associated with shorter recurrence-free survival (P=0.04 and P=0.007, respectively). Moreover, the combination of high SIRT1 and SIRT2 expression was an independent prognostic factor for shorter recurrence-free survival (P=0.002) and overall survival (P=0.022). In vitro studies showed that SIRT1 and/or SIRT2 downregulation significantly decreased proliferation of NSCLC.

Conclusions

Our results support the hypothesis that SIRT1 and SIRT2 have a protumorigenic role in lung cancer, promoting cell proliferation. Moreover, the expression of these proteins is associated with poor prognosis in NSCLC patients and may help to identify those NSCLC patients with high risk of recurrence that could benefit from adjuvant therapy after resection.     

Estrogen Receptor Expression Is Associated with DNA Repair Capacity in Breast Cancer

Estrogen-receptor-positive (ER+) tumors employ complex signaling that engages in crosstalk with multiple pathways through genomic and non-genomic regulation. A greater understanding of these pathways is important for developing improved biomarkers that can better determine treatment choices, risk of recurrence and cancer progression. Deficiencies in DNA repair capacity (DRC) is a hallmark of breast cancer (BC); therefore, in this work we tested whether ER signaling influences DRC. We analyzed the association between ER positivity (% receptor activation) and DRC in 270 BC patients, then further stratified our analysis by HER2 receptor status. Our results show that among HER2 negative, the likelihood of having low DRC values among ER- women is 1.92 (95% CI: 1.03, 3.57) times the likelihood of having low DRC values among ER+ women, even adjusting for different potential confounders (p<0.05); however, a contrary pattern was observed among HER2 positives women. In conclusion, there is an association between DRC levels and ER status, and this association is modified by HER2 receptor status. Adding a DNA repair capacity test to hormone receptor testing may provide new information on defective DNA repair phenotypes, which could better stratify BC patients who have ER+ tumors. ER+/HER2- tumors are heterogeneous, incompletely defined, and clinically challenging to treat; the addition of a DRC test could better characterize and classify these patients as well as help clinicians select optimal therapies, which could improve outcomes and reduce recurrences.     

CLPTM1L Is Overexpressed in Lung Cancer and Associated with Apoptosis

CLPTM1L is believed to be associated with lung cancer. However, there is little information regarding its expression and function. Here using immunohistochemistry, we found that CLPTM1L expression was markedly increased in lung cancer tissues relative to normal tissues, especially in lung adenocarcinoma. CLPTM1L expression was not found to be associated with stages, smoking status, lymph node metastasis, or T lymphocyte infiltration but with differentiation stage. We found CLPTM1L to be enriched in the mitochondrial compared with plasma membrane protein extracts. CLPTM1L-EGFP transfection showed that the molecule product was expressed in cytoplasm and indicated the mitochondrial localization stained with mitochondrial marker MitoTracker. CLPTM1L transferred lung cancer cell line 95-D showed no growth inhibition or cell apoptosis, but it did show inhibited sensitivity to cis-diamminedichloroplatinum(II) (cisplatin, CDDP). Knockdown of CLPTM1L by RNAi did not interfere with cell proliferation but it did increase cell sensitivity to CDDP and activation of caspase-9 and caspase-3/7. These data indicate CLPTM1L is a mitochondria protein and that it may be associated with anti-apoptotic mechanism which affects drug-resistance in turn.     

Expression of Beclin Family Proteins Is Associated with Tumor Progression in Oral Cancer

Background

Beclin 1 and Beclin 2 are autophagy-related proteins that show similar amino acid sequences and domain structures. Beclin 1 established the first connection between autophagy and cancer. However, the role of Beclin 2 in cancer is unclear. The aims of this study were to analyze Beclin 1 and Beclin 2 expressions in oral cancer tissues and in cell lines, and to evaluate their possible roles in cancer progression.

Methods

We investigated Beclin 1 and Beclin 2 expressions by immunohistochemistry in 195 cases of oral cancer. The prognostic roles of Beclin 1 and Beclin 2 were analyzed statistically. In vitro, overexpression and knockdown of Beclin proteins were performed on an oral cancer cell line, SAS. The immunofluorescence and autophagy flux assays confirmed that Beclin proteins were involved in autophagy. The impacts of Beclin 1 and Beclin 2 on autophagy and tumor growth were evaluated by conversion of LC3-I to LC3-II and by clonogenic assays, respectively.

Results

Oral cancer tissues exhibited aberrant expressions of Beclin 1 and Beclin 2. The cytoplasmic Beclin 1 and Beclin 2 expressions were unrelated in oral cancer tissues. In survival analyses, high cytoplasmic Beclin 1 expression was associated with low disease specific survival, and negative nuclear Beclin 1 expression was associated with high recurrent free survival. Patients with either high or low cytoplasmic Beclin 2 expression had significantly lower overall survival and disease specific survival rates than those with moderate expression. In oral cancer cells, overexpression of either Beclin 1 or Beclin 2 led to autophagy activation and increased clonogenic survival; knockdown of Beclin 2 impaired autophagy and increased clonogenic survival.

Conclusions

Our results indicated that distinct patterns of Beclin 1 and Beclin 2 were associated with aggressive clinical outcomes. Beclin 1 overexpression, as well as Beclin 2 overexpression and depletion, contributed to tumor growth. These findings suggest Beclin proteins are associated with tumorigenesis.     

Attenuated XPC Expression Is Not Associated with Impaired DNA Repair in Bladder Cancer

Bladder cancer has a high incidence with significant morbidity and mortality. Attenuated expression of the DNA damage response protein Xeroderma Pigmentosum complementation group C (XPC) has been described in bladder cancer. XPC plays an essential role as the main initiator and damage-detector in global genome nucleotide excision repair (NER) of UV-induced lesions, bulky DNA adducts and intrastrand crosslinks, such as those made by the chemotherapeutic agent Cisplatin. Hence, XPC protein might be an informative biomarker to guide personalized therapy strategies in a subset of bladder cancer cases. Therefore, we measured the XPC protein expression level and functional NER activity of 36 bladder tumors in a standardized manner. We optimized conditions for dissociation and in vitro culture of primary bladder cancer cells and confirmed attenuated XPC expression in approximately 40% of the tumors. However, NER activity was similar to co-cultured wild type cells in all but one of 36 bladder tumors. We conclude, that (i) functional NER deficiency is a relatively rare phenomenon in bladder cancer and (ii) XPC protein levels are not useful as biomarker for NER activity in these tumors.     

Methylation of the Claudin 1 Promoter Is Associated with Loss of Expression in Estrogen Receptor Positive Breast Cancer

Downregulation of the tight junction protein claudin 1 is a frequent event in breast cancer and is associated with recurrence, metastasis, and reduced survival, suggesting a tumor suppressor role for this protein. Tumor suppressor genes are often epigenetically silenced in cancer. Downregulation of claudin 1 via DNA promoter methylation may thus be an important determinant in breast cancer development and progression. To investigate if silencing of claudin 1 has an epigenetic etiology in breast cancer we compared gene expression and methylation data from 217 breast cancer samples and 40 matched normal samples available through the Cancer Genome Atlas (TCGA). Moreover, we analyzed claudin 1 expression and methylation in 26 breast cancer cell lines. We found that methylation of the claudin 1 promoter CpG island is relatively frequent in estrogen receptor positive (ER+) breast cancer and is associated with low claudin 1 expression. In contrast, the claudin 1 promoter was not methylated in most of the ER-breast cancers samples and some of these tumors overexpress claudin 1. In addition, we observed that the demethylating agents, azacitidine and decitabine can upregulate claudin 1 expression in breast cancer cell lines that have a methylated claudin 1 promoter. Taken together, our results indicate that DNA promoter methylation is causally associated with downregulation of claudin 1 in a subgroup of breast cancer that includes mostly ER+ tumors, and suggest that epigenetic therapy to restore claudin 1 expression might represent a viable therapeutic strategy in this subtype of breast cancer.     

Expression of NgBR Is Highly Associated with Estrogen Receptor Alpha and Survivin in Breast Cancer

NgBR is a type I receptor with a single transmembrane domain and was identified as a specific receptor for Nogo-B. Our recent findings demonstrated that NgBR binds farnesylated Ras and recruits Ras to the plasma membrane, which is a critical step required for the activation of Ras signaling in human breast cancer cells and tumorigenesis. Here, we first use immunohistochemistry and real-time PCR approaches to examine the expression patterns of Nogo-B and NgBR in both normal and breast tumor tissues. Then, we examine the relationship between NgBR expression and molecular subtypes of breast cancer, and the roles of NgBR in estrogen-dependent survivin signaling pathway. Results showed that NgBR and Nogo-B protein were detected in both normal and breast tumor tissues. However, the expression of Nogo-B and NgBR in breast tumor tissue was much stronger than in normal breast tissue. The statistical analysis demonstrated that NgBR is highly associated with ER-positive/HER2-negative breast cancer. We also found that the expression of NgBR has a strong correlation with the expression of survivin, which is a well-known apoptosis inhibitor. The correlation between NgBR and survivin gene expression was further confirmed by real-time PCR. In vitro results also demonstrated that estradiol induces the expression of survivin in ER-positive T47D breast tumor cells but not in ER-negative MDA-MB-468 breast tumor cells. NgBR knockdown with siRNA abolishes estradiol-induced survivin expression in ER-positive T47D cells but not in ER-negative MDA-MB-468 cells. In addition, estradiol increases the expression of survivin and cell growth in ER-positive MCF-7 and T47D cells whereas knockdown of NgBR with siRNA reduces estradiol-induced survivin expression and cell growth. In summary, these results indicate that NgBR is a new molecular marker for breast cancer. The data suggest that the expression of NgBR may be essential in promoting ER-positive tumor cell proliferation via survivin induction in breast cancer.     

High Bak Expression Is Associated with a Favorable Prognosis in Breast Cancer and Sensitizes Breast Cancer Cells to Paclitaxel

Breast cancer has become the leading cause of cancer-related death among women. A large number of patients become resistant to drug chemotherapy. Paclitaxel (Taxol) is an effective chemotherapeutic agent used to treat cancer patients. Taxol has been widely used in human malignancies including breast cancer because it can stabilize microtubules resulting in cell death by causing an arrest during the G2/M phase of the cell cycle. Pro-apoptotic Bcl-2 antagonist killer 1 (Bak) plays an important role in Taxol-induced apoptosis in breast cancer. In our present study, we investigated the expression of the Bak protein and clinicopathological correlations in a large sample of breast cancer tissues by immunohistochemistry. We found that the percentage of high scores of Bak expression in breast cancer was significantly lower than that of the non-cancerous breast control tissue. In addition, lower Bak expression was positively associated with the clinical TNM stage of breast cancer with a significant decrease in overall survival compared with those with higher Bak expression especially in the Luminal and HER2 subtypes. Importantly, higher Bak expression predicted a favorable clinical outcome in the cases treated with Taxol indicated by a higher overall survival than that of patients with lower Bak expression especially in Luminal and HER2 subtypes. Furthermore, these results were confirmed in vitro since overexpression of Bak sensitized breast cancer cells to Taxol by inhibiting proliferation and promoting apoptosis; in contrast, downregulation of Bak through siRNA transfection inhibited Taxol induced-apoptosis. Therefore, our results demonstrate that Bak acts as a sensitive biomarker and favorable prognostic factor for Taxol treatment in breast cancer. The restoration of Bak expression would be therapeutically beneficial for Taxol resistant breast cancer patients.     

Upregulation of SATB1 Is Associated with Prostate Cancer Aggressiveness and Disease Progression

Disease aggressiveness remains a critical factor to the progression of prostate cancer. Transformation of epithelial cells to mesenchymal lineage, associated with the loss of E-cadherin, offers significant invasive potential and migration capability. Recently, Special AT-rich binding protein (SATB1) has been linked to tumor progression. SATB1 is a cell-type restricted nuclear protein, which functions as a tissue-specific organizer of DNA sequences during cellular differentiation. Our results demonstrate that SATB1 plays significant role in prostate tumor invasion and migration and its nuclear localization correlates with disease aggressiveness. Clinical specimen analysis showed that SATB1 was predominantly expressed in the nucleus of high-grade tumors compared to low-grade tumor and benign tissue. A progressive increase in the nuclear levels of SATB1 was observed in cancer tissues compared to benign specimens. Similarly, SATB1 protein levels were higher in a number of prostate cancer cells viz. HPV-CA-10, DU145, DUPro, PC-3, PC-3M, LNCaP and C4-2B, compared to non-tumorigenic PZ-HPV-7 cells. Nuclear expression of SATB1 was higher in biologically aggressive subclones of prostate cancer cells with their respective parental cell lines. Furthermore, ectopic SATB1 transfection conferred increased cell motility and invasiveness in immortalized human prostate epithelial PZ-HPV-7 cells which correlated with the loss of E-cadherin expression. Consequently, knockdown of SATB1 in highly aggressive human prostate cancer PC-3M cells inhibited invasiveness and tumor growth in vivo along with increase in E-cadherin protein expression. Our findings demonstrate that SATB1 has ability to promote prostate cancer aggressiveness through epithelial-mesenchymal transition.     

A Proteomics Analysis Reveals 9 Up-Regulated Proteins Associated with Altered Cell Signaling in Colon Cancer Patients

Colorectal cancer is the second most common cancer in women and third most common cancer in men. Cell signaling alterations in colon cancer, especially in aggressive metastatic tumors, require further investigations. The present study aims to compare the expression pattern of proteins associated with cell signaling in paired tumor and non-tumor samples of patients with colon cancer, as well as to define the cluster of proteins to differentiate patients with non-metastatic (Dukes’ grade B) and metastatic (Dukes’ grade C&D) colon cancer. Frozen tumor and non-tumor samples were collected after tumor resection from 19 patients with colon cancer. The Panorama? Antibody Microarray-Cell Signaling kits were used for the analyses. The expression ratios of paired tumor/non-tumor samples were calculated for the each protein. We employed R packages ‘samr’, ‘gplots’, ‘supclust’ (pelora, wilma algorithms), ‘glmnet’ for the differential expression analysis, supervised clustering and penalized logistic regression. Significance analysis of microarrays revealed 9 significantly up-regulated proteins, including protein kinase C gamma, c-Myc, MDM2, pan cytokeratin, and 1 significantly down-regulated protein (GAP1) in tumoral mucosa. Pan-cytokeratin and APP were up-regulated in tumor versus non-tumor tissue, and were selected in the predictive cluster to discriminate colon cancer type. Higher levels of S-100b and phospho-Tau-pSer199/202 were confirmed as the predictors of non-metastatic colon cancer by all employed regression/clustering methods. Deregulated proteins in colon cancer are involved in oncogenic signal transduction, cell cycle control, and regulation of cytoskeleton/transport. Further studies are needed to validate potential protein markers of colon cancer development and metastatic progression.     

A New Polymorphism Biomarker rs629367 Associated with Increased Risk and Poor Survival of Gastric Cancer in Chinese by Up-Regulated miRNA-let-7a Expression

Background

Variant in pri-miRNA could affect miRNA expression and mature process or splicing efficiency, thus altering the hereditary susceptibility and prognosis of cancer. We aimed to assess miRNA-let-7 single nucleotide polymorphisms (SNP) associated with the risk and prognosis of gastric cancer (GC) as predicting biomarkers, and furthermore, its possible mechanisms.

Methods

A two-stage case-control study was designed to screen four miRNA SNPs (pri-let-7a-2 rs629367 and rs1143770, pri-let-7a-1 rs10739971, pri-let-7f-2 rs17276588) in 107 GC patients, 107 atrophic gastritis (AG), and matched 124 controls using PCR-RFLP. Two promising SNPs were validated in another independent 1949 samples (including 579 gastric cancer patients, 649 atrophic gastritis and 721 controls) using Sequenom MassARRAY platform and sequencing.

Results

We found that pri-let-7a-2 rs629367 CC variant genotype was associated with increased risks of gastric cancer and atrophic gastritis by 1.83-fold and 1.86-fold, respectively. For gastric cancer prognosis, patients with rs629367 CC genotype had significantly poorer survival than patients with AA genotype (log-rank P = 0.004). We further investigated the let-7a expression levels in serum and found that let-7a expression elevated gradually for rs629367 AA, CA, CC genotype in the atrophic gastritis group (P = 0.043). Furthermore, we confirmed these findings in vitro study by overexpressing let-7a carrying pri-let-7a-2 wild-type A or polymorphic-type C allele (P<0.001).

Conclusions

pri-let-7a-2 rs629367 CC genotype could increase the risks of gastric cancer as well as atrophic gastritis and was also associated with poor survival of gastric cancer, which possibly by affecting the mature let-7a expression, and could serve as a predicting biomarker for high-risk and poor prognosis of gastric cancer.