PTEN-mediated AKT activation contributes to the reduced apoptosis among Indian oral squamous cell carcinoma patients

Prognostic potential of Akt, pAkt(Ser473) and pAkt(Thr308) immunoreactivity in relation to HPV prevalence in head and neck squamous cell carcinoma patients

BACKGROUND

The prognosis of squamous cell carcinoma of head and neck (HNSCC) patients remains relatively poor over the last years. Tobacco, alcohol and active human papillomavirus (HPV) infection are involved in HNSCC development. Akt is a serine-threonine protein kinase with main phosphorylation sites at Thr308 and Ser473, which are critical to generate a high level of Akt activity.

MATERIALS AND METHODS

The aim of the study was to compare the expression and prognostic potential of total Akt and its 2 phosphorylated forms - pAkt(Ser473) and pAkt(Thr308) in relation to HPV status in HNSCC patients. The expression levels of proteins were assessed immunohistochemically. To select independent prognostic factors univariate and multivariate analyses with Cox proportional regression model were performed.

RESULTS

Among HNSCC with active HPV16 infection significantly more tumors with high Akt (67.86%, p = 0.026) and low pAkt(Ser473) (64.29%, p = 0.000) expressions were found as compared to those with HPV negativity, while there was no significant difference in the pAkt(Thr308) expression level between HPV positive and negative tumors (p = 0.359). In the whole group of HNSCC patients independent favorable prognostic factors were low T stage, low pAkt(Thr308) expression, HPV16 active infection presence (for OS and DFS) and female gender (for OS only).

CONCLUSIONS

Our results indicate an important role of pAkt(Thr308) as prognostic biomarker for HNSCC patients. There is a high probability that using Akt inhibitors would improve therapeutical benefits and treatment effectiveness, especially in HNSCC patients with high expression of pAkt.

The radiobiology of HPV-positive and HPV-negative head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, with reported incidences of ~800 000 cases each year. One of the critical determinants in patient response to radiotherapy, particularly for oropharyngeal cancers, is human papillomavirus (HPV) status where HPV-positive patients display improved survival rates and outcomes particularly because of increased responsiveness to radiotherapy. The increased radiosensitivity of HPV-positive HNSCC has been largely linked with defects in the signalling and repair of DNA double-strand breaks. Therefore, strategies to further radiosensitise HPV-positive HNSCC, but also radioresistant HPV-negative HNSCC, have focussed on targeting key DNA repair proteins including PARP, DNA-Pk, ATM and ATR. However, inhibitors against CHK1 and WEE1 involved in cell-cycle checkpoint activation have also been investigated as targets for radiosensitisation in HNSCC. These studies, largely conducted using established HNSCC cell lines in vitro, have demonstrated variability in the response dependent on the specific inhibitors and cell models utilised. However, promising results are evident targeting specifically PARP, DNA-Pk, ATR and CHK1 in synergising with radiation in HNSCC cell killing. Nevertheless, these preclinical studies require further expansion and investigation for translational opportunities for the effective treatment of HNSCC in combination with radiotherapy.

MicroRNA‑655 suppresses cell proliferation and invasion in oral squamous cell carcinoma by directly targeting metadherin and regulating the PTEN/AKT pathway

MicroRNAs (miRNAs) are important regulators of a variety of biological processes and their dysregulation is closely related to cancer formation and progression. Therefore, examination of aberrantly expressed miRNAs in oral squamous cell carcinoma (OSCC) may provide important clues for the diagnosis and treatment of patients with OSCC. The aim of the present study was to determine miRNA (miR)‑655‑3p expression in OSCC tissues and cell lines, and to investigate the biological roles and mechanisms of miR‑655‑3p associated with OSCC. Data from the present study indicated that miR‑655 expression was significantly downregulated in human OSCC tissues and cell lines. Overexpression of miR‑655 attenuated cell proliferation and invasion in OSCC in vitro. Metadherin (MTDH) mRNA was predicted as a potential target of miR‑655 by bioinformatics analysis, and this was confirmed by luciferase reporter assay, reverse transcription‑quantitative polymerase chain reaction and western blot analysis. In OSCC tissues, MTDH was highly expressed and inversely correlated with miR‑655 expression levels. MTDH overexpression reversed the inhibitory effects of miR‑655 mimics in OSCC cells. Notably, the upregulation of miR‑655 expression inhibited the activation of the phosphatase and tensin homolog (PTEN)/RAC‑α serine/threonine‑protein kinase (AKT) pathway in OSCC cells. Therefore, these results may provide the first evidence that miR‑655 targets MTDH to inhibit proliferation and invasion of OSCC by inhibiting PTEN/AKT signaling. Thus, the restoration of miR‑655 expression may be a novel therapeutic strategy for patients with OSCC.

Allelic loss at PTEN locus leads to progression of colorectal carcinoma among North Indian patients

We evaluated the loss of heterozygosity (LOH) at 10q^23.3 locus of microsatellite markers; D10S198, D10S192, and D10S541 of PTEN gene in 223 North Indian colorectal cancer (CRC) specimens. DNA was isolated and microsatellite-specific markers polymerase chain reaction was performed. Out of total 223 cases 102 showed LOH for at least one of the locus. In addition, thereto a significant association was found with the clinicopathologic features like grade of differentiation, clinical stage, invasion, lymph node invasion, and the clinical outcome (p < 0.05). These data argue that the given markers to check the possible LOH of PTEN gene at locus 10q^23.3 could be considered as one of the diagnostic markers in CRC.

PTEN enhances G2/M arrest in etoposide-treated MCF‑7 cells through activation of the ATM pathway

As an effective tumor suppressor, phosphatase and tensin homolog (PTEN) has attracted the increased attention of scientists. Recent studies have shown that PTEN plays unique roles in the DNA damage response (DDR) and can interact with the Chk1 pathway. However, little is known about how PTEN contributes to DDR through the ATM-Chk2 pathway. It is well-known that etoposide induces G2/M arrest in a variety of cell lines, including MCF-7 cells. The DNA damage-induced G2/M arrest results from the activation of protein kinase ataxia telangiectasia mutated (ATM), followed by the activation of Chk2 that subsequently inactivates CDC25C, resulting in G2/M arrest. In the present study, we assessed the contribution of PTEN to the etoposide-induced G2/M cell cycle arrest. PTEN was knocked down in MCF-7 cells by specific shRNA, and the effects of PTEN on the ATM-Chk2 pathway were investigated through various approaches. The results showed that knockdown of PTEN strongly antagonized ATM activation in response to etoposide treatment, and thereby reduced the phosphorylation level of ATM substrates, including H2AX, P53 and Chk2. Furthermore, depletion of PTEN reduced the etoposide-induced phosphorylation of CDC25C and strikingly compromised etoposide-induced G2/M arrest in the MCF-7 cells. Altogether, we demonstrated that PTEN plays a unique role in etoposide-induced G2/M arrest by facilitating the activation of the ATM pathway, and PTEN was required for the proper activation of checkpoints in response to DNA damage in MCF-7 cells.

Immunohistochemical expression of phosphatase and tensin homolog in histologic gradings of oral squamous cell carcinoma

Context:

Phosphatase and tensin homolog (PTEN) is a tumor suppressor gene located on chromosome 10q23. PTEN has its major function in the regulation of cell adhesion, cell cycle arrest, migration, apoptosis programming, and differentiation. This genomic region suffers loss of heterozygosity in many human cancers.

Aims:

The aim of this study was to compare the immunohistochemical expression of PTEN in normal oral mucosa and oral squamous cell carcinoma (OSCC) and to correlate the PTEN expression in gradings of OSCC.

Materials and Methods:

Thirty cases of paraffin tissue sections of previously diagnosed OSCC were taken. Of thirty cases, ten were well differentiated, ten were moderately differentiated, and ten were poorly differentiated. As a control, ten paraffin sections of oral normal mucosa tissue specimens were taken from patients undergoing extractions. The sections were stained for immunohistochemical expression of PTEN. The cells stained by PTEN antibody were counted, and an immunohistochemical score was obtained.

Statistical Analysis Used:

Statistical analysis was done using Mann–Whitney's test and Kruskal–Wallis test.

Results:

Statistical analysis revealed that there was a significant difference between normal mucosa and OSCC in immunohistochemistry staining. However, there was no significant difference in PTEN expression among gradings of OSCC.

Conclusions:

The study concluded that there was a decrease in PTEN expression in OSCC than normal mucosa. It also concluded that PTEN is a tumor suppressor gene which has a wide role in oral carcinogenesis.

Aloe vera: Potential candidate in health management via modulation of biological activities

Treatment based on natural products is rapidly increasing worldwide due to the affordability and fewer side effects of such treatment. Various plants and the products derived from them are commonly used in primary health treatment, and they play a pivotal role in the treatment of diseases via modulation of biochemical and molecular pathways. Aloe vera, a succulent species, produces gel and latex, plays a therapeutic role in health management through antioxidant, antitumor, and anti-inflammatory activities, and also offers a suitable alternative approach for the treatment of various types of diseases. In this review, we summarize the possible mechanism of action and the therapeutic implications of Aloe vera in health maintenance based on its modulation of various biological activities.

Review on molecular and chemopreventive potential of nimbolide in cancer

Cancer is the most dreaded disease in human and also major health problem worldwide. Despite its high occurrence, the exact molecular mechanisms of the development and progression are not fully understood. The existing cancer therapy based on allopathic medicine is expensive, exhibits side effects; and may also alter the normal functioning of genes. Thus, a non-toxic and effective mode of treatment is needed to control cancer development and progression. Some medicinal plants offer a safe, effective and affordable remedy to control the cancer progression. Nimbolide, a limnoid derived from the neem (Azadirachta indica) leaves and flowers of neem, is widely used in traditional medical practices for treating various human diseases. Nimbolide exhibits several pharmacological effects among which its anticancer activity is the most promising. The previous studies carried out over the decades have shown that nimbolide inhibits cell proliferation and metastasis of cancer cells. This review highlights the current knowledge on the molecular targets that contribute to the observed anticancer activity of nimbolide related to induction of apoptosis and cell cycle arrest; and inhibition of signaling pathways related to cancer progression.

Therapeutic Implications of Black Seed and Its Constituent Thymoquinone in the Prevention of Cancer through Inactivation and Activation of Molecular Pathways

The cancer is probably the most dreaded disease in both men and women and also major health problem worldwide. Despite its high prevalence, the exact molecular mechanisms of the development and progression are not fully understood. The current chemotherapy/radiotherapy regime used to treat cancer shows adverse side effect and may alter gene functions. Natural products are generally safe, effective, and less expensive substitutes of anticancer chemotherapeutics. Based on previous studies of their potential therapeutic uses, Nigella sativa and its constituents may be proved as good therapeutic options in the prevention of cancer. Black seeds are used as staple food in the Middle Eastern Countries for thousands of years and also in the treatment of diseases. Earlier studies have shown that N. sativa and its constituent thymoquinone (TQ) have important roles in the prevention and treatment of cancer by modulating cell signaling pathways. In this review, we summarize the role of N. sativa and its constituents TQ in the prevention of cancer through the activation or inactivation of molecular cell signaling pathways.

An analysis of the epidemiological and etiological factors of oral tumors of young adults in a Central-Eastern European population

The etiology of tumors in young age is not precisely known yet, but studies on the topic generally agree that in this group of patients the traditionally known behavioural risk factors (tobacco and alcohol abuse) play no or a significantly less important role. Oral squamous cell carcinoma occurring at a young age is a topic of utmost importance that is extensively and intensively researched as, while the overall incidence of oral cancer is decreasing worldwide, that of squamous cell carcinoma diagnosed in young adults is steadily increasing. The present article aims at presenting the main questions and characteristics of tumors in young adults in Central-Eastern Europe and in developed West European countries as contrasted to tumors found in middle aged and elderly patients. Factors influencing the development of oral cancer include regulatory factors of the cell cycle, the inherited vulnerability of the genetic code of certain proteins and the presence of HPV infection with an oncogenic genotype. The connections of HPV infection and genetic damages are studied intensively. It is known that the prevalence of oral HPV infections is growing with a background of potentially changing sexual habits. It is debated, however, whether smoking and alcohol consumption could have a connection to HPV associated oral cancer and whether the spread of HPV in itself could be an explanation for the growing occurrence of young-age tumors. There is no consensus in the literature as to the prognostic significance of age. Some research groups have found a better life expectancy for young patients, while other authors found a worse prognosis for these patients. It is known that the prognosis of head and neck tumors, the prevalence of HPV infections as well as genetic mutations show regional and ethnic variations. This might be explained by differences in the degree of development of a preventive system, in the quality of care and in the attitudes of young patients towards visiting a doctor. The study is made difficult by incomparable patient selection criteria as well as by the question of the intraoral localisation of tumors as an independent risk factor.