Chemotherapeutic drug resistance in the management of head and neck cancer

IP3R1 dysregulation via mir-200c-3p/SSFA2 axis contributes to taxol resistance in head and neck cancer

Head and neck cancer (HNC) is the sixth most common malignancy worldwide. Although current modalities offer a wide variety of therapy choices, head and neck carcinoma has poor prognosis due to its diagnosis at later stages and development of resistance to current therapeutic tools. In the current study, we aimed at exploring the roles of miR-200c-3p during head and neck carcinogenesis and acquisition of taxol resistance. We analyzed miR-200c-3p levels in HNC clinical samples and cell lines using quantitative real-time polymerase chain reaction and evaluated the effects of differential miR-200c-3p expression on cancer-related cellular phenotypes using in-vitro tools. We identified and characterized a direct target of miR-200c-3p using in-silico tools, luciferase and various in-vitro assays. We investigated potential involvement of miR-200c-3p/SSFA2 axis in taxol resistance in-vitro. We found miR-200c-3p expression as significantly downregulated in both HNC tissues and cells compared to corresponding controls. Ectopic miR-200c-3p expression in HNC cells significantly inhibited cancer-related phenotypes such as viability, clonogenicity, migration, and invasion. We, then, identified SSFA2 as a direct target of miR-200c-3p and demonstrated that overexpression of SSFA2 induced malignant phenotypes in HNC cells. Furthermore, we found reduced miR-200c-3p expression in parallel with overexpression of SSFA2 in taxol resistant HNC cells compared to parental sensitive cells. Both involved in intracellular cytoskeleton remodeling, we found that SSFA2 works collaboratively with IP3R1 to modulate resistance to taxol in HNC cells. When considered collectively, our results showed that miR-200c-3p acts as a tumor suppressor microRNA and targets SSFA2/IP3R1 axis to sensitize HNC cells to taxol.

Targeting Squalene Epoxidase Confers Metabolic Vulnerability and Overcomes Chemoresistance in HNSCC

Cisplatin resistance poses a substantial hurdle in effectively treating head and neck squamous cell carcinoma (HNSCC). Utilizing multiple tumor models and examining an internal HNSCC cohort, squalene epoxidase (SQLE) is pinpointed as a key driver of chemoresistance and tumorigenesis, operating through a cholesterol-dependent pathway. Comprehensive transcriptomic analysis reveals that SQLE is essential for maintaining c-Myc transcriptional activity by stabilizing the c-Myc protein and averting its ubiquitin-mediated degradation. Mechanistic investigation demonstrates that SQLE inhibition diminishes Akt's binding affinity to lipid rafts via a cholesterol-dependent process, subsequently deactivating lipid raft-localized Akt, reducing GSK-3β phosphorylation at S9, and increasing c-Myc phosphorylation at T58, ultimately leading to c-Myc destabilization. Importantly, employing an Sqle conditional knockout mouse model, SQLE's critical role in HNSCC initiation and progression is established. The preclinical findings demonstrate the potent synergistic effects of combining terbinafine and cisplatin in arresting tumor growth. These discoveries not only provide novel insights into the underlying mechanisms of SQLE-mediated cisplatin resistance and tumorigenesis in HNSCC but also propose a promising therapeutic avenue for HNSCC patients unresponsive to conventional cisplatin-based chemotherapy.

A matched cohort study of standard chemo-radiotherapy versus radiotherapy alone in elderly nasopharyngeal carcinoma patients

The impact of standard chemo-radiotherapy (CRT) as preferred therapy for elderly patients (age≥60 years) with nasopharyngeal carcinoma (NPC) remains unclear. Therefore, a strict matched cohort study was conducted to compare the survival and treatment toxicity of standard chemo-radiotherapy in the elderly NPC patients with those of radiotherapy (RT) alone. From 1998 to 2003, total 498 newly diagnosed elderly non-metastatic NPC patients were abstracted and classified into two groups by the treatments they received. For each patient in the CRT group, a matched pair in RT group was identified by matching for gender, age, histological type, T and N classifications, RT dose to primary tumor and neck nodes, and days of radiotherapy. Treatment tolerability and toxicity were clarified, and treatment outcomes were calculated and compared between the two groups. Two groups were well balanced in clinical characteristics because of the strict matching conditions. Totally 87 pairs can be assessed according to the criteria. The 5-year OS, CSS, FFS, and LR-FFS for CRT and RT groups were 62% versus 40% (P=0.013), 67% versus 47% (P=0.018), 65% versus 53% (log-rank: P=0.064, Breslow: P=0.048), and 88% versus 72%, (P=0.019), respectively. There was no significant difference in 5-year D-FFS between the two groups (75% vs. 73%, P=0.456). The CRT group experienced significantly more Grade ≥3 acute mucositis (46.0% vs. 28.7%, P= 0.019). We concluded that standard chemo-radiotherapy can achieve a reasonable local and regional control in elderly NPC patients with acceptable and reversible acute toxicity. However, distant metastasis remains the dominant failure pattern. When the elderly NPC patients are in good performance status following a complete evaluation of overall functional status and comorbidity conditions, standard chemo-radiotherapy is worthy of recommendation.

Insulin-like growth factor (IGF) signaling in tumorigenesis and the development of cancer drug resistance

One of the greatest obstacles to current cancer treatment efforts is the development of drug resistance by tumors. Despite recent advances in diagnostic practices and surgical interventions, many neoplasms demonstrate poor response to adjuvant or neoadjuvant radiation and chemotherapy. As a result, the prognosis for many patients afflicted with these aggressive cancers remains bleak. The insulin-like growth factor (IGF) signaling axis has been shown to play critical role in the development and progression of various tumors. Many basic science and translational studies have shown that IGF pathway modulators can have promising effects when used to treat various malignancies. There also exists a substantial body of recent evidence implicating IGF signaling dysregulation in the dwindling response of tumors to current standard-of-care therapy. By better understanding both the IGF-dependent and -independent mechanisms by which pathway members can influence drug sensitivity, we can eventually aim to use modulators of IGF signaling to augment the effects of current therapy. This review summarizes and synthesizes numerous recent investigations looking at the role of the IGF pathway in drug resistance. We offer a brief overview of IGF signaling and its general role in neoplasia, and then delve into detail about the many types of human cancer that have been shown to have IGF pathway involvement in resistance and/or sensitization to therapy. Ultimately, our hope is that such a compilation of evidence will compel investigators to carry out much needed studies looking at combination treatment with IGF signaling modulators to overcome current therapy resistance.

Identification of microRNAs and mRNAs associated with multidrug resistance of human laryngeal cancer Hep-2 cells

Multidrug resistance (MDR) poses a serious impediment to the success of chemotherapy for laryngeal cancer. To identify microRNAs and mRNAs associated with MDR of human laryngeal cancer Hep-2 cells, we developed a multidrug-resistant human laryngeal cancer subline, designated Hep-2/v, by exposing Hep-2 cells to stepwise increasing concentrations of vincristine (0.02-0.96'µM). Microarray assays were performed to compare the microRNA and mRNA expression profiles of Hep-2 and Hep-2/v cells. Compared to Hep-2 cells, Hep-2/v cells were more resistant to chemotherapy drugs (≈ 45-fold more resistant to vincristine, 5.1-fold more resistant to cisplatin, and 5.6-fold more resistant to 5-fluorouracil) and had a longer doubling time (42.33 ± 1.76 vs 28.75 ± 1.12'h, P<0.05), higher percentage of cells in G0/G1 phase (80.98 ± 0.52 vs 69.14 ± 0.89, P<0.05), increased efflux of rhodamine 123 (95.97 ± 0.56 vs 12.40 ± 0.44%, P<0.01), and up-regulated MDR1 expression. A total of 7 microRNAs and 605 mRNAs were differentially expressed between the two cell types. Of the differentially expressed mRNAs identified, regulator of G-protein signaling 10, high-temperature requirement protein A1, and nuclear protein 1 were found to be the putative targets of the differentially expressed microRNAs identified. These findings may open a new avenue for clarifying the mechanisms responsible for MDR in laryngeal cancer.

In vitro chemosensitivity of head and neck cancer cell lines

Background

Systemic treatment of head and neck squamous cell carcinoma (HNSCC) includes a variety of antineoplastic drugs. However, drug-resistance interferes with the effectiveness of chemotherapy. Preclinical testing models are needed in order to develop approaches to overcome chemoresistance.

Methods

Ten human cell lines were obtained from HNSCC, including one with experimentally-induced cisplatin resistance. Inhibition of cell growth by seven chemotherapeutic agents (cisplatin, carboplatin, 5- fluorouracil, methotrexate, bleomycin, vincristin, and paclitaxel) was measured using metabolic MTT-uptake assay and correlated to clinically-achievable plasma concentrations.

Results

All drugs inhibited cell growth in a concentration-dependent manner with an IC50 comparable to that achievable in vivo. However, response curves for methotrexate were unsatisfactory and for paclitaxel, the solubilizer cremophor EL was toxic. Cross-resistance was observed between cisplatin and carboplatin.

Conclusion

Chemosensitivity of HNSCC cell lines can be determined using the MTT-uptake assay. For DNA-interfering cytostatics and vinca alkaloids this is a simple and reproducible procedure. Determined in vitro chemosensitivity serves as a baseline for further experimental approaches aiming to modulate chemoresistance in HNSCC with potential clinical significance.

Tobacco abuse relates to significantly reduced survival of patients with oropharyngeal carcinomas

This study represents an in-depth evaluation of the impact of smoking and alcohol consumption on patients' outcome in 809 cases of oropharyngeal carcinoma. Prognostic parameters and additional information such as smoking and drinking habits were evaluated referring to the patients' case notes at the time point of first diagnosis. The overall 10-year survival rate was 45.5%, whereas 33.4% of the patients remained relapse-free. The great majority (92%) of patients had a history of smoking or were current smokers, whereas only 8% of the collective never smoked in their lifetime. Interestingly, we found a significant reduction of 10-year survival rates for smokers (28.8%) in comparison with nonsmokers (43.1%) and ex-smokers (P=0.0007). This study presents data from a large cohort of patients with oropharyngeal carcinoma providing evidence for a relationship between alcohol and tobacco consumption, and significantly worse prognosis.

Collateral methotrexate resistance in cisplatin-selected murine leukemia cells

Resistance to anticancer drugs is a major cause of failure of many therapeutic protocols. A variety of mechanisms have been proposed to explain this phenomenon. The exact mechanism depends upon the drug of interest as well as the tumor type treated. While studying a cell line selected for its resistance to cisplatin we noted that the cells expressed a > 25,000-fold collateral resistance to methotrexate. Given the magnitude of this resistance we elected to investigate this intriguing collateral resistance. From a series of investigations we have identified an alteration in a membrane protein of the resistant cell as compared to the sensitive cells that could be the primary mechanism of resistance. Our studies reviewed here indicate decreased tyrosine phosphorylation of a protein (molecular mass = 66) in the resistant cells, which results in little or no transfer of methotrexate from the medium into the cell. Since this is a relatively novel function for tyrosine phosphorylation, this information may provide insight into possible pharmacological approaches to modify therapeutic regimens by analyzing the status of this protein in tumor samples for a better survival of the cancer patients.

Chemosensitivity of head and neck squamous carcinoma cell lines is not primarily correlated with glutathione level but is modified by glutathione depletion

Glutathione has a variety of important physiological functions in cellular metabolism and defense, including protection from radicals, oxidative stress, and electrophilic compounds. On the basis of this interaction with both endogenous and synthetic substances, glutathione and the key enzyme for its conjugation, glutathione S-transferase, appear to be critical determinants in tumor cell resistance to several antineoplastic drugs, e.g. platinum analogs. In ten established head and neck cancer cell lines (UM-SCC 10A, 10B, 11B, 14A, 14B, 14C, and 22B, HLac79, 8029NA, and 8029DDP4) chemosensitivity to cisplatin, carboplatin, 5-fluorouracil, and bleomycin, as well as cellular glutathione content and activity of glutathione S-transferase were determined. The results revealed no correlation between the sensitivity of tumor cells to any of the drugs tested and the level of glutathione or the activity of glutathione S-transferase. However, the cisplatin-resistant subpopulation 8029DDP4 showed the highest glutathione level and marked cross-resistance to bleomycin. Glutathione depletion with buthionine sulfoximine led to moderately increased sensitivity towards cisplatin and carboplatin in all cell lines, but did not affect their response to 5-fluorouracil or bleomycin. These results suggest that the level of glutathione or the activity of glutathione S-transferase is not a suitable parameter for the assessment of chemosensitivity in head and neck squamous-cell carcinoma lines. However, response to platinum analogs is influenced by alterations of the initial intracellular glutathione concentration.