Transketolase-like protein 1 expression in recurrent oral squamous cell carcinoma after curative resection: a case report

The role of transketolase in human cancer progression and therapy

Transketolase (TKT) is an enzyme that is ubiquitously expressed in all living organisms and has been identified as an important regulator of cancer. Recent studies have shown that the TKT family includes the TKT gene and two TKT-like (TKTL) genes; TKTL1 and TKTL2. TKT and TKTL1 have been reported to be involved in the regulation of multiple cancer-related events, such as cancer cell proliferation, metastasis, invasion, epithelial-mesenchymal transition, chemoradiotherapy resistance, and patient survival and prognosis. Therefore, TKT may be an ideal target for cancer treatment. More importantly, the levels of TKTL1 were detected using EDIM technology for the early detection of some malignancies, and TKTL1 was more sensitive and specific than traditional tumor markers. Detecting TKTL1 levels before and after surgery could be used to evaluate the surgery's effect. While targeted TKT suppresses cancer in multiple ways, in some cases, it has detrimental effects on the organism. In this review, we discuss the role of TKT in different tumors and the detailed mechanisms while evaluating its value and limitations in clinical applications. Therefore, this review provides a basis for the clinical application of targeted therapy for TKT in the future, and a strategy for subsequent cancer-related research.

MiR-196b affects the progression and prognosis of human LSCC through targeting PCDH-17

OBJECTIVE

To explore the effect of miR-196bon the biological features of human laryngeal squamous cell carcinoma (LSCC) through targeting PCDH-17.

METHODS

miR-196b and PCDH-17 expressions were determined in tissues, and the targeting relation of miR-196b and PCDH-17 was verified through dual-luciferase reporter system. In vitro, Hep-2 cells were divided into the Control, miR-196b inhibitors, miR-NC, PCDH-17, and miR-196b mimics+PCDH-17 groups. The miR-196b and PCDH-17 expressions were determined by qRT-PCR or/and Western blot, and the biological features by MTT, Annexin V-FITC/PI, wound-healing and Transwell assays.

RESULTS

MiR-196b was found to be up-regulated, while PCDH-17 was down-regulated in a negative correlation in LSCC patients, which was related to histological grade and TNM stage. And low expression of miR-196b and high expression of PCDH-17 contributed to an increase in the 5-year-survival rate of LSCC patients. Besides, miR-196b directly targeted PCDH-17, while miR-196b inhibitors could up-regulate the PCDH-17 in Hep-2 cells. Moreover, miR-196b inhibitors and PCDH-17 curbed Hep-2 cell proliferation but facilitated the apoptosis, with decreases in cell invasion and migration. In addition, no statistical significance was found in cell proliferation, apoptosis, invasion and migration between Control group and miR-196b mimics+PCDH-17 group.

CONCLUSION

LSCC patients exhibited the up-regulated miR-196b and down-regulated PCDH-17, which are correlated with the major clinical features and prognosis. Inhibiting miR-196b may suppress proliferation, migration and invasion abilities, and promote apoptosis of Hep-2 cells via targeting PCDH-17.

Transketolase-like protein 1 expression predicts poor prognosis in colorectal cancer

BACKGROUND

Transketolase-like protein 1 (TKTL1) is an isoform of tranketolase, a key protein in a cancer cell's glucose metabolism that causes rapid cell growth and controls the non-oxidative part of the pentose phosphate pathway (PPP). Its overexpression occurs in several human cancer types. Our purpose was to study whether TKTL1 expression in colorectal cancer tissue associates with these patients' prognosis.

METHODS

We collected retrospectively patient data and tissue samples from 840 colorectal cancer patients treated at Helsinki University Hospital, then stained tumor tissue microarrays for TKTL1 by immunohistochemistry, and compared immunohistochemical tissue expression with clinico-pathological parameters and survival.

RESULTS

High expression of TKTL1 associated with high Dukes stage, non-mucinous adenocarcinoma, and left-sided disease. Patients with high TKTL1 expression had poorer prognosis than those with low expression, with a 5-year disease-specific survival of 55.7% vs. 62.7%.

CONCLUSION

We show that high TKTL1 in tumor tissue can lead to poor survival in colorectal cancer. TKTL1 thus can serve as a candidate marker for identifying patients at risk of recurrent disease.

Oral cancer cells may rewire alternative metabolic pathways to survive from siRNA silencing of metabolic enzymes

Background

Cancer cells may undergo metabolic adaptations that support their growth as well as drug resistance properties. The purpose of this study is to test if oral cancer cells can overcome the metabolic defects introduced by using small interfering RNA (siRNA) to knock down their expression of important metabolic enzymes.

Methods

UM1 and UM2 oral cancer cells were transfected with siRNA to transketolase (TKT) or siRNA to adenylate kinase (AK2), and Western blotting was used to confirm the knockdown. Cellular uptake of glucose and glutamine and production of lactate were compared between the cancer cells with either TKT or AK2 knockdown and those transfected with control siRNA. Statistical analysis was performed with student T-test.

Results

Despite the defect in the pentose phosphate pathway caused by siRNA knockdown of TKT, the survived UM1 or UM2 cells utilized more glucose and glutamine and secreted a significantly higher amount of lactate than the cells transferred with control siRNA. We also demonstrated that siRNA knockdown of AK2 constrained the proliferation of UM1 and UM2 cells but similarly led to an increased uptake of glucose/glutamine and production of lactate by the UM1 or UM2 cells survived from siRNA silencing of AK2.

Conclusions

Our results indicate that the metabolic defects introduced by siRNA silencing of metabolic enzymes TKT or AK2 may be compensated by alternative feedback metabolic mechanisms, suggesting that cancer cells may overcome single defective pathways through secondary metabolic network adaptations. The highly robust nature of oral cancer cell metabolism implies that a systematic medical approach targeting multiple metabolic pathways may be needed to accomplish the continued improvement of cancer treatment.