MICA and MICB overexpression in oral squamous cell carcinoma

NKG2D Natural Killer Cell Receptor-A Short Description and Potential Clinical Applications

Natural Killer (NK) cells are natural cytotoxic, effector cells of the innate immune system. They can recognize transformed or infected cells. NK cells are armed with a set of activating and inhibitory receptors which are able to bind to their ligands on target cells. The right balance between expression and activation of those receptors is fundamental for the proper functionality of NK cells. One of the best known activating receptors is NKG2D, a member of the CD94/NKG2 family. Due to a specific NKG2D binding with its eight different ligands, which are overexpressed in transformed, infected and stressed cells, NK cells are able to recognize and attack their targets. The NKG2D receptor has an enormous significance in various, autoimmune diseases, viral and bacterial infections as well as for transplantation outcomes and complications. This review focuses on the NKG2D receptor, the mechanism of its action, clinical relevance of its gene polymorphisms and a potential application in various clinical settings.

Race-associated expression of MHC class I polypeptide-related sequence A (MICA) in prostate cancer

Despite the lack of a complete understanding of the disparities involved, prostate cancer (PCa) has both higher incidence and death rates in African American Men (AAM) relative to those of Caucasian American Men (CAM). MHC class I polypeptide related sequence A (MICA) is an innate immunity protein involved in tumor immunoevasion. Due to a lack of reports of race-specific expression of MICA in PCa, we evaluated MICA expression in patients' tumors and in cell lines from a racially diverse origin. Immunohistochemistry was done on a tissue microarray (TMA) with antibodies against MICA. Tumor MICA mRNA was assessed by data mining using Oncomine and PROGeneV2. Surface MICA and release rate of soluble (s) MICA was evaluated in PCa cell lines originally derived from African American (MDA-PCa-2b) or Caucasian (LNCaP and DU-145) PCa patients. Prostate tumor tissue had a 1.7-fold higher MICA expression relative to normal tissue (p < .0001). MICA immunoreactivity in PCa tissue from AAM was 24% lower (p = .002) compared to CAM. Survival analysis revealed a marginal association of low MICA with poor overall survival (OS) (p = .058). By data mining analysis, a 2.9-fold higher level of MICA mRNA was evidenced in tumor compared to normal tissue (p < .0001). Tumors from AAM had 24% lower levels of MICA mRNA compared to tumors from CAM (p = .038), and poor prognosis was found for patients with lower MICA mRNA (p = .028). By flow cytometry analysis, cell fraction positive for surface MICA was of 3% in MDA-PCa-2b cells, 54% in DU-145 cells, and 67% in LNCaP cells (p < .0001). sMICA was detected in DU-145 and LNCaP cells, but was not detected in MDA-PCa-2b cells. Both LNCaP and DU-145 cells were sensitive to cytolysis mediated by Natural killer (NK) cells. MDA-PCa-2b cells, however were between 1.3-fold at 10:1 Effector:Target (E:T) ratio (p < .0001) and 2-fold at 50:1 E:T ratio (p < .0001) more resistant to NK-mediated cytolysis relative to cells from Caucasian origin. These results suggest that MICA expression may be related to the aggressive nature of PCa. Our findings also demonstrate for the first time that there are variations in MICA expression in the context of racial differences. This study establishes a rationale for further investigation of MICA as a potential race-specific prognostic marker in PCa.

HPV: Molecular pathways and targets

Infection of high-risk human papillomaviruses (HPVs) is a prerequisite for the development of cervical carcinoma. HPV infections are also implicated in the development of other types of carcinomas. Chronic or persistent infection of HPV is essential but HPV alone is inadequate, additional endogenous or exogenous cues are needed along with HPV to induce cervical carcinogenesis. The strategies that high-risk HPVs have developed in differentiating epithelial cells to reach a DNA-synthesis competent state leading to tumorigenic transformation are basically due to overexpression of the E6 and E7 oncoproteins and the activation of diverse cellular regulatory or signaling pathways that are targeted by them. Moreover, the Wnt/β-catenin/Notch and phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathways are deregulated in various cancers, and have also been implicated in HPV-induced cancers. These are basically related to the "cancer hallmarks," and include sustaining proliferative signals, the evasion of growth suppression and immune destruction, replicative immortality, inflammation, invasion, metastasis and angiogenesis, as well as genome instability, resisting cell death, and deregulation of cellular energetics. These information could eventually aid in identifying or developing new diagnostic, prognostic biomarkers, and may contribute to design more effective targeted therapeutics and treatment strategies. Although surgery, chemotherapy and radiotherapy can cure more than 90% of women with early stage cervical cancer, the recurrent and metastatic disease remains a major cause of cancer mortality. Numerous efforts have been made to design new drugs and develop gene therapies to treat cervical cancer. In recent years, research on treatment strategies has proposed several options, including the role of HPV E5, E6, and E7 oncogenes, which are retained and overexpressed in most of the cervical cancers and whose respective oncoproteins are critical to the induction and maintenance of the malignant phenotype. Other efforts have been focused on antitumor immunotherapy strategies. It is known that during the development of cervical cancer, a cascade of abnormal events is induced, including disruption of cell cycle control, perturbation of antitumor immune response, alteration of gene expression, deregulation of microRNA and cancer stem cell and stemness related markers expression could serve as novel molecular targets for reliable diagnosis and treatment of HPV-positive cancers. However, the search for new proposals for disease control and prevention has brought new findings and approaches in the context of molecular biology indicating innovations and perspectives in the early detection and prevention of the disease. Thus, in this article, we discuss molecular signaling pathways activated by HPV and potential targets or biomarkers for early detection or prevention and the treatment of HPV-associated cancers.

Proinflammatory cytokines as serum biomarker in oral carcinoma-A prospective multi-biomarker approach

BACKGROUND

Inflammation and cell-mediated immunity have a key role in different stages of carcinogenesis. The aim of this prospective study was to assess serum levels of proinflammatory cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), soluble interleukin-2 receptor (sIL-2R), tumor necrosis factor alpha (TNF-α), and MHC class I polypeptide-related sequence B (MICB) in patients with oral premalignant lesion (OPL), oral squamous cell carcinoma (OSCC), and healthy controls in a multi-biomarker approach as a potential diagnostic and prognostic tool for OSCC.

MATERIAL AND METHODS

A total of 205 patients (81 with OSCC, 75 with OPL, and 49 healthy controls) were included in this prospective study. Cytokine concentrations were measured by commercial enzyme linked immunoassay and chemiluminescence immunoassay.

RESULTS

IL-6, IL-8, and sIL-2R were significantly elevated in OSCC patients compared to healthy controls and to OPL patients. Higher T-Grade (>T2) and positive lymph node involvement resulted in significantly higher IL-6 values (P < .001 and P = .037). IL-6 serum values ≥5 pg/mL (n = 45) and sIL-2R serum values ≥623 U/mL (n = 19) indicated a significant lower survival rate compared to OSCC patients with low IL-6 (n = 36) and sIL-2R values (n = 62, P = .023 and P = .026). ROC and classification tree analyses identified the combination of IL-6 and IL-8 as diagnostic markers with good diagnostic accuracy.

CONCLUSION

In conclusion, IL-6, IL-8, and sIL-2R are strongly associated with OSCC oncogenesis and IL-6 and sIL-2R seem to be promising and potent biomarkers for evaluating patients' prognosis.

Soluble MICA is elevated in pancreatic cancer: Results from a population based case-control study

Pancreatic cancer is diagnosed at a late stage and has one of the highest cancer mortality rates in the United States, creating an urgent need for novel early detection tools. A candidate biomarker for use in early detection is the soluble MHC class I-related chain A (s-MICA) ligand, which pancreatic tumors shed to escape immune detection. The objective of this study was to define the association between s-MICA levels and pancreatic cancer, in a population-based case-control study. S-MICA was measured in 143 pancreatic cancer cases and 459 controls. Unconditional logistic regression was used to calculate odds ratio (OR) for pancreatic cancer and 95% confidence intervals (CI). There was a positive association between increasing s-MICA levels and pancreatic cancer: compared to the lowest tertile, the ORs for pancreatic cancer were 1.25 (95%CI: 0.75-2.07) and 2.10 (95%CI: 1.29-3.42) in the second and highest tertiles, respectively (P-trend = 0.02). Our study supports previous work demonstrating a positive association between plasma s-MICA levels and pancreatic cancer.

Elevation of soluble major histocompatibility complex class I related chain A protein in malignant and infectious diseases in Chinese patients

Background

Elevation of soluble major histocompatibility complex class I chain-related gene A (sMICA) products in serum has been linked to tissue/organ transplantation, autoimmune diseases and some malignant disorders. Cells infected by microbiological pathogens may release sMICA, whereas less is known whether and to what extent serum sMICA levels may change in infectious diseases.

Methods

The present study determined serum sMICA levels by enzyme-linked immunosorbent assay (ELISA) in a southern China population, including patients (n = 1041) suffering from several types of malignant and infectious diseases and healthy controls (n = 141).

Results

Relative to controls, serum sMICA elevation was significant in patients of hepatic cancer, and was approaching statistical significance in patients with lung, gastric and nasopharyngeal cancers. sMICA elevation was also associated with some bacterial (Enterobacteriaceae, Mycobacterium tuberculosis, non-fermenting Gram-negative bacteria and Gram-positive cocci), viral (hepatitis B and C) and the Microspironema pallidum infections.

Conclusion

Serum sMICA levels may be informative for the diagnosis of some malignant and infectious diseases. The results also indicate that microbiological infections should be considered as a potential confounding clinical condition causing serum sMICA elevation while using this test to evaluate the status of other disorders, such as cancers, host-graft response and autoimmune diseases.

Membrane progesterone receptors (mPRs) mediate progestin induced antimorbidity in breast cancer cells and are expressed in human breast tumors

Membrane progesterone receptors (mPRs) have been detected in breast cancer cells and tissues, but their roles in cancer progression remain unclear. Here, we demonstrate the localization, signaling, and antiapoptotic actions of mPRs in two nuclear progesterone receptor (PR)-negative breast cancer cell lines, SKBR3 and MDA-MB-468 (MB468), and mPR expression in human breast tumor biopsies. mPRα, mPRβ, and mPRγ subtypes were detected in both cell lines as well as in breast tumor tissues from 13 individuals irrespective of nuclear steroid receptor expression. Competitive receptor binding studies with a selective PR ligand, R5020, and an mPR agonist, Org OD 02-0 confirmed the presence of functional mPRs on both cancer cell lines. Progesterone treatment of either cell line caused rapid activation of an inhibitory G protein, as well as activation of p42/44 MAP kinase. Treatment with progesterone or Org OD 02-0 significantly decreased cell death and apoptosis in response to serum starvation, whereas testosterone, 17β-estradiol, dexamethasone, and R5020 and RU486 were ineffective. Progesterone treatment of MB468 cells also increased mitochondrial membrane potential and Akt activity, but no decrease in caspase 3 activity was observed. Knockdown of mPRα expression in MB468 cells by siRNA transfection blocked the inhibitory effects of progesterone on cell death. The results indicate that progesterone can act through mPRs to inhibit apoptosis in breast cancer cells. The involvement of mPRs in the development or progression of breast tumor growth through inhibition of cell death is an intriguing possibility and requires further investigation.

Immunotherapy for lung cancers

Lung cancer is the leading cause of cancer-related deaths worldwide. Although treatment methods in surgery, irradiation, and chemotherapy have improved, prognosis remains unsatisfactory and developing new therapeutic strategies is still an urgent demand. Immunotherapy is a novel therapeutic approach wherein activated immune cells can specifically kill tumor cells by recognition of tumor-associated antigens without damage to normal cells. Several lung cancer vaccines have demonstrated prolonged survival time in phase II and phase III trials, and several clinical trials are under investigation. However, many clinical trials involving cancer vaccination with defined tumor antigens work in only a small number of patients. Cancer immunotherapy is not completely effective in eradicating tumor cells because tumor cells escape from host immune scrutiny. Understanding of the mechanism of immune evasion regulated by tumor cells is required for the development of more effective immunotherapeutic approaches against lung cancer. This paper discusses the identification of tumor antigens in lung cancer, tumor immune escape mechanisms, and clinical vaccine trials in lung cancer.

Tumor vaccines in 2010: need for integration

Induction of tumor-specific immunity is an attractive approach to cancer therapy, however to date every major pivotal trial has resulted in failure. While the phenomena of tumor-mediated immune suppression has been known for decades, only recently have specific molecular pathways been elucidated, and for the first time, rationale means of intervening and observing results of intervention have been developed. In this review we describe major advances in our understanding of tumor escape from immunological pressure and provide some possible therapeutic scenarios for enhancement of efficacy in future cancer vaccine trials.

Proteasome regulation of ULBP1 transcription

Killer lymphocytes recognize stress-activated NKG2D ligands on tumors. We examined NKG2D ligand expression in head and neck squamous cell carcinoma (HNSCC) cells and other cell lines. HNSCC cells typically expressed MHC class I chain-related gene A (MICA), MICB, UL16-binding protein (ULBP)2, and ULBP3, but they were uniformly negative for cell surface ULBP1 and ULBP4. We then studied how cancer treatments affected NKG2D ligand expression. NKG2D ligand expression was not changed by most cancer-relevant treatments. However, bortezomib and other proteasome inhibitor drugs with distinct mechanisms of action dramatically and specifically up-regulated HNSCC ULBP1 mRNA and cell surface protein. Proteasome inhibition also increased RNA for ULBP1 and other NKG2D ligands in nontransformed human keratinocytes. Proteasome inhibitor drugs increased ULBP1 transcription by acting at a site in the 522-bp ULBP1 promoter. Although the DNA damage response pathways mediated by ATM (ataxia-telangiectasia, mutated) and ATR (ATM and Rad3-related) signaling had been reported to up-regulate NKG2D ligand expression, we found that ULBP1 up-regulation was not inhibited by caffeine and wortmannin, inhibitors of ATM/ATR signaling. ULBP1 expression in HNSCC cells was not increased by several ATM/ATR activating treatments, including bleomycin, cisplatin, aphidicolin, and hydroxyurea. Ionizing radiation caused ATM activation in HNSCC cells, but high-level ULBP1 expression was not induced by gamma radiation or UV radiation. Thus, ATM/ATR signaling was neither necessary nor sufficient for high-level ULBP1 expression in human HNSCC cell lines and could not account for the proteasome effect. The selective induction of ULBP1 expression by proteasome inhibitor drugs, along with variable NKG2D ligand expression by human tumor cells, indicates that NKG2D ligand genes are independently regulated.

Detection and screening of oral cancer and pre-cancerous lesions

Oral cancer is a fatal disease, accounting for the fourth highest incidence of malignancy in males and the seventh in females in Taiwan. The relatively high prevalence of oral cancer in Taiwan is mainly because there is a high-risk group of 2.5 million people with the habit of smoking and betel nut chewing. Unfortunately, 50% of new cases in our medical center who present with TNM stage III or IV lesions have a shorter than 5-year survival after treatment. This highlights the need for: (1) early treatment of fresh oral cancer cases; (2) screening of the high-risk population to detect new lesions; (3) careful follow-up of cases after treatment; and (4) detection of occult early neck nodal adenopathy in surgical cases. It is generally accepted that prevention and screening of oral cancer are equally important to treatment due to its location. In this review article, we describe the nature of oral cancer and highlight the various conventional and novel methods of screening for this disease and ongoing important related research. Related literature is reviewed and future work that needs to be done is detailed.

Discovery of novel biomarkers in oral submucous fibrosis by microarray analysis

Oral submucous fibrosis (OSF) is a high-risk precancerous condition of the oral cavity. Areca nut chewing is its key etiologic factor, but the full pathogenesis is still obscure. In this study, microarray analysis was used to characterize the mRNA changes of 14,500 genes in four OSF and four normal buccal mucosa samples to identify novel biomarkers of OSF. Five candidate genes with the most differential changes were chosen for validation. The correlation between clinicopathologic variables of 66 OSF patients and the expression of each gene was assessed by immunohistochemistry. The microarray analysis showed that 661 genes were up-regulated (fold value >2) and 129 genes were down-regulated (fold value <0.5) in OSF (q < 0.01). The top three up-regulated genes [Loricrin, Cartilage oligomeric matrix protein (COMP), Cys-X-Cys ligand 9 (CXCL9)] with the largest fold changes and the top two down-regulated genes [keratin 19 (KRT19), cytochrome P450 3A5 (CYP 3A5)] with the most significantly differential changes in OSF were chosen as candidate biomarkers. In immunohistochemical results, the expression of Loricrin and COMP showed statistically significant association with histologic grade of OSF (P = 0.03 and 0.006, respectively). COMP was found to be overexpressed frequently in patients with the habit of areca nut chewing for more than 4 years (P = 0.002). CYP 3A5 was revealed an inverse correlation with histologic grade (P = 0.04). This pilot study showed that five novel genes might play important roles in the pathogenesis of OSF and may be clinically useful for early detection of OSF.

An association between the MICA-A5.1 allele and an increased susceptibility to oral squamous cell carcinoma in Japanese patients

BACKGROUND

Recently, a new polymorphic gene family called the major histocompatibility complex class I chain-related gene A (MICA) was discovered about 40 kb centromeric to HLA-B gene. The MICA protein, expressed on epithelial cells and many kinds of tumor cells, serves to regulate immune function. The MICA protein is thought to activate immune function on mucosal tissue by binding to NKG2D which is expressed on most natural killer cells, CD8 positive T cells, and gamma delta T cells. An association between MICA gene polymorphisms and the development of oral squamous cell carcinoma (OSCC) has also been reported.

OBJECTIVE

This study was designed to test this association in Japanese patients with OSCC.

METHODS

The (GCT)(n) polymorphisms of the MICA gene was investigated in 123 patients with OSCC and 188 normal controls using polymerase chain reaction amplification and denaturing polyacrylamide gel electrophoresis.

RESULTS

Five alleles, namely A4, A5, A6, A9, and A5.1, were found in both groups. The phenotype frequency of the MICA-A5.1 allele was significantly higher in patients with OSCC when compared with normal controls (OR 1.707, 95% CI 0.76-3.45, P=0.042). Also, the microsatellite frequency of the MICA-A5.1 allele was significantly higher in patients with OSCC compared with normal controls (OR 1.664, 95% CI 0.82-3.42, P=0.021). Lastly, the frequency of the MICA-A5.1 allele was significantly higher in those with lymph node metastasis from OSCC compared with normal controls (OR 2.605, 95% CI 1.14-5.27, P=0.026).

CONCLUSIONS

These results suggest that the MICA-A5.1 allele may be associated with an increased susceptibility to OSCC in Japan.