Martin Grimm

Analyzing the inflammatory microenvironment has become an important issue in the management of oral squamous cell carcinoma (OSCC). Pretreatment C-reactive protein (CRP) levels, leucocytes, monocytes, lymphocytes, neutrophils, basophils, eosinophils, platelets, neutrophil-to-lymphocyte ratio (NLR), derived NLR (dNLR), lymphocyte-to-monocyte ratio (LMR), and platelet-to-lymphocyte ratio (PLR) derived from the peripheral blood were analyzed. Receiver operating characteristic (ROC) curves determined a cut-off value for each parameter in 146 patients with OSCC compared with 93 controls and the results were associated with clinicopathological characteristics. CRP expression of tumors was measured by immunohistochemistry. ROC analysis determined cut-off values for CRP levels, leucocytes, monocytes, lymphocytes, neutrophils, NLR, dNLR, LMR, PLR and showed significant differences between the OSCC and control group. Compared with single laboratory tests calculated ratios were superior in measuring sensitivity and specificity of OSCC disease. NLR was significant directly associated and correlated with PLR. LMR was significant inversely associated and correlated with NLR and PLR. Immunohistochemical analysis did not show CRP expression of OSCCs. This study highlights the first analysis for cut-off values of pretreatment single laboratory tests and calculated ratios, which are strongly needed for a follow-up of cancer patients. Additionally, the calculated baselines can be used as a goal for successful immunotherapies in the future. The links between NLR, LMR, and PLR might be helpful for the clinical course (monitoring) of cancer patients and have been first described for OSCC in this study. Taken together, analyzing these data provides an additional practical guideline of further postoperative OSCC management.

One of the common malignant tumors of the head and neck worldwide with generally unfavorable prognosis is squamous cell carcinoma (OSCC) of the oral cavity. Early detection of primary, secondary, or recurrent OSCC by liquid biopsy tools is much needed. Twelve blood biomarkers were used for monitoring a case of OSCC suffering from precancerous oral lichen ruber planus mucosae (OLP). After curative R0 tumor resection of primary OSCC (buccal mucosa), elevated epitope detection in monocytes (EDIM)-Apo10, EDIM-transketolase-like-1 (TKTL1), squamous cell carcinoma antigen (SCC-Ag), total serum lactate dehydrogenase (LDH), and its anaerobic isoforms (LDH-4, LDH-5) decreased to normal levels. Three and six months after surgery, transformation of suspicious mucosal lesions has been accompanied with an increase of EDIM scores, total serum LDH values, and a metabolic shift from aerobic (decrease of LDH-1, LDH-2) to anaerobic (increase of LDH-4, LDH-5) conditions. Two months later, secondary OSCC was histopathologically analyzed after tissue biopsy. Cytokeratin fraction 21-1 (CYFRA 21-1), carcinoembryonic antigen (CEA), and carbohydrate antigen 19-9 (CA19-9) were not affected during the clinical course of carcinogenesis. A combination strategy using a standardized panel of established (metabolic) blood biomarkers (TKTL1, LDH, LDH isoenzymes) is worth and can be recommended among others (apoptosis resistance-related Apo10, SCC-Ag) for early detection and diagnosis of primary, secondary, and recurrent OSCC. A tandem strategy utilizing (metabolic pronounced) routine liquid biopsies with imaging techniques may enhance diagnosis of OSCC in the future. Although we demonstrated the diagnostic utility of separated liquid biopsies in our previous study cohorts, further investigations in a larger patient cohort are necessary to recommend this combination strategy (EDIM blood test, LDH value, metabolic shift of LDH isoenzymes, and others, e.g., SCC-Ag or immunophenotyping) as a diagnostic tool for the addition to the OSCC staging system and as a routine procedure in the aftercare.

Recent studies have shown an increase in the incidence of oral squamous cell carcinoma (OSCC) in younger patients. The hypothesis that tumors could be hormonally induced during pregnancy or in young female patients without the well-known risk factors alcohol or tobacco abuse seems to be plausible. Estrogen Receptor alpha (ER?) and Progesterone Receptor (PR) expression were analyzed in normal oral mucosa (n=5), oral precursor lesions (simple hyperplasia, n=11; squamous intraepithelial neoplasia, SIN I-III, n=35), and OSCC specimen. OSCCs were stratified in a young female (n=7) study cohort and older patients (n=46). In the young female study cohort three patients (n=3/7) developed OSCC during or shortly after pregnancy. Breast cancer tissues were used as positive control for ER? and PR expression. ER? expression was found in four oral precursor lesions (squamous intraepithelial neoplasia, SIN I-III, n=4/35, 11%) and in five OSCC specimen (n=5/46, 11%). The five ER? positive OSCC samples were older male patients. All patients within the young female study cohort were negatively stained for both ER? and PR. ER expression could be regarded as a seldom risk factor for OSCC. PR expression seems to be not relevant for the development of OSCC

The immune system is important for elimination of cancer cells. Tumors including oral squamous cell carcinoma (OSCC) are capable of escaping detection by host immune cells through apoptotic depletion of tumor-infiltrating lymphocytes (TILs). Circulating peripheral blood lymphocytes (PBLs) and corresponding TILs of tumor specimen were evaluated before and after curative tumor resection (n = 30) compared with PBLs of controls (n = 87). PBLs were characterized for the total number of T cells (CD3⁺), T helper cells (Th, CD3⁺/CD4⁺), regulatory T cells (Treg, CD4⁺/CD25⁺/CD127^low), cytotoxic T cells (Tc, CD3⁺/CD8⁺), activated T cells (CD3⁺/HLA-DR⁺), and natural killer (NK) cells (CD3⁻/CD16⁺/CD56⁺). In tumor tissue, the prevalence of CD3⁺, CD4⁺, and CD8⁺ TILs was assessed using immunohistochemistry, whereas the incidence of apoptosis was assessed using terminal deoxynucleotidyl transferase deoxyuridinetriphosphate nick-end labeling (TUNEL) assay. In PBLs of pretreated OSCC patients, a highly significant decrease in total number of T cells (p = 0.0001), Th cells (p < 0.0001), Treg cells (p < 0.0001), Tc cells (p < 0.0001), and NK cells (p = 0.0037) were found compared with controls. Decreased PBLs of OSCC patients were correlated with decreased numbers of corresponding TILs, which were associated with increased detection of apoptosis in the tumor tissue. Compared with the controls, the total number of T cells remained unchanged after surgery but the total number of NK cells significantly increased. Standardized immunophenotyping of OSCC may help to identify patients likely to benefit from cancer immunotherapy strategies and/or chemoradiation. Finally, future attempts to enhance an effective tumor-reactive immune response by immunotherapy or vaccination should be made by promoting tumor-specific Th and/or Tc cell/NK cell responses.

Thiamine-dependent enzymes (TDEs) linking glycolysis with the tricarboxylic acid cycle (TCA) pyruvate dehydrogenase (PDH), of the pentose phosphate pathway transketolases (TKTs), the TCA alpha-ketoglutarate deydrogenase (KGDH)/2-oxoglutarate dehydrogenase (OGDH) complex, and the amino acid catabolism branched-chain alpha-ketoacid dehydrogenase (BCKDH) complex are crucial factors for tumor metabolism. The expression of these enzymes has not been analyzed for carcinogenesis of oral squamous cell carcinoma (OSCC) with special focus on new targeted metabolic therapies as yet. TDEs PDH, KGDH (OGDH), and BCKDH were analyzed in normal oral mucosa (n = 14), oral precursor lesions (simple hyperplasia, n = 21; squamous intraepithelial neoplasia, SIN I–III, n = 35), and OSCC specimen (n = 46) by immunohistochemistry and western blot (WB) analysis in OSCC tumor cell lines. Although the total numbers of PDH and KGDH (OGDH) positive samples decreased in OSCC, both enzymes were significantly overexpressed in the carcinogenesis of OSCC compared with normal tissue. BCKDH has been demonstrated to be significantly overexpressed in the carcinogenesis of OSCC. Specificity of the antibodies was confirmed by WB analysis. This is the first study showing increased expression of TDEs in OSCC. Metabolic targeting of TDEs (including TKTs) by antagonistic compounds like oxythiamine or oxybenfothiamine may be a useful strategy to sensitize cancer cells to common OSCC cancer therapies.

The potential use of determination of biomarkers in blood for the monitoring of surgical removal of oral squamous cell carcinomas (OSCC) was evaluated using the epitope detection in monocytes (EDIM) technology. In tumor specimen, elevated Apo10 and transketolase-like 1 (TKTL1) expression was analyzed by immunohistochemistry. Apo10 and TKTL1 biomarkers have been used prospectively for EDIM blood test in patients with primary and/or recurrent OSCC (n = 92) before surgery and after curative tumor resection (n = 45). There were highly significant (p < 0.0001) correlations found between EDIM blood scores and the tissue expression of both biomarkers measured by immunohistochemistry (Apo10: n = 89/92, 97 %; TKTL1: n = 90/92, 98 %). EDIMApo10 and EDIM-TKTL1 scores were positive in 92 % (EDIM-Apo10: n = 85/92) and 93 % (EDIM-TKTL1: n = 86/92), respectively, in patients with OSCC before surgery. The combined score EDIM-Apo10/EDIM-TKTL1 increased significantly the detection rate of tumors to 97 % (n = 89/92). After surgery, the EDIM-TKTL1 and EDIMApo10 scores significantly decreased in 75.6 and 86.7 % of the patients (p < 0.0001), respectively, in the aftercare. The correlation of TKTL1 and Apo10 immunohistochemistry with the blood test results indicates that the EDIM blood test could serve as a non-invasive diagnostic tool (liquid biopsy) to assess surgical removal of OSCC by determination of two biomarkers. This is the first study that has been demonstrated a reliable and successful monitoring of OSCC cancer patients by a blood test. The specific and significant decrease of EDIM-TKTL1 and EDIM-Apo10 scores after surgery could serve as a new tool for monitoring surgical removal of OSCC.

Glutaminolysis is a crucial factor for tumor metabolism in the carcinogenesis of several tumors but has not been clarified for oral squamous cell carcinoma (OSCC) yet. Expression of glutaminolysis-related solute carrier family 1, member 5 (SLC1A5)/neutral amino acid transporter (ASCT2), glutaminase (GLS), and glutamate dehydrogenase (GLDH) was analyzed in normal oral mucosa (n = 5), oral precursor lesions (simple hyperplasia, n = 11; squamous intraepithelial neoplasia, SIN I–III, n = 35), and OSCC specimen (n = 42) by immunohistochemistry. SLC1A5/ASCT2 and GLS were significantly overexpressed in the carcinogenesis of OSCC compared with normal tissue, while GLDH was weakly detected. Compared with SIN I–III SLC1A5/ASCT2 and GLS expression were significantly increased in OSCC. GLDH expression did not significantly differ from SIN I–III compared with OSCC. This study shows the first evidence of glutaminolysis-related SLC1A5/ASCT2, GLS, and GLDH expression in OSCC. The very weak GLDH expression indicates that glutamine metabolism is rather related to nucleotide or protein/hexosamine biosynthesis or to the function as an antioxidant (glutathione) than to energy production or generation of lactate through entering the tricarboxylic acid cycle. Overcoming glutaminolysis by targeting c-Myc oncogene (e.g. by natural compounds) and thereby cross-activation of mammalian target of rapamycin complex 1 or SLC1A5/ASCT2, GLS inhibitors may be a useful strategy to sensitize cancer cells to common OSCC cancer therapies.

Resistance to programmed cell death (apoptosis) is a crucial factor for the carcinogenesis of oral squamous cell carcinoma (OSCC). Vitamin D (calcitriol) may overcome apoptosis resistance in tumor cells of OSCC. Vitamin D receptor (VDR) expression in oral precancerous lesions of OSCC has not been analyzed and serum vitamin D level seems to be a predictor of cancer development. Expression of VDR was analyzed in normal oral mucosa (n=5), oral precursor lesions (simple hyperplasia, n=11; squamous intraepithelial neoplasia, SIN I-III, n=35), and OSCC specimen (n=42) by immunohistochemistry (IHC). Moreover, serum vitamin D levels were measured by 25(OH)D3 (calcidiol) in patients with OSCC (n=42) and correlated with IHC results. Expression of VDR was significantly increased in precancerous and OSCC compared with normal tissue. Compared with SIN I-III lesions VDR expression significantly decreased in OSCC. Severe vitamin D deficiency was detected in our OSCC patient cohort but there was no significant correlation analyzed between serum vitamin D levels and corresponding immunohistochemically detected VDR expression in OSCC. Our survey provides the first evidence of VDR expression in precancerous lesions of OSCC. Apoptosis induction of VDR+ cells in oral precancerous lesions and OSCC by natural vitamin D or synthetic vitamin D compounds could be useful for chemoprevention. Moreover, systemically and/or locally applied, these compounds may act as sensitizers for apoptosis mediated by radio-, and chemotherapy treatment in OSCC.