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Head and neck squamous cell carcinoma (HNSCC) is characterized by the 5-year survival rate of approximately 50%. Despite aggressive surgical, radiation, and chemotherapeutic interventions, 30% to 40% of patients die from the development of recurrent or disseminated disease that is resistant to chemotherapy. As a model of recurrence, we examined the effects of cisplatin on the ability of head and neck cancer cells to initiate tumors in a xenotransplant model. HNSCC cells were treated in vitro with cisplatin at a concentration that elicited >99% cytotoxicity and assessed for tumorigenic potential in nonobese diabetic/severe combined immunodeficient mice. HNSCC cells that survived cisplatin treatment formed tumors in nonobese diabetic/severe combined immunodeficient mice more efficiently than nontreated cells. Cisplatin-resistant cells were characterized using clonal analysis, in vivo imaging, and transcriptomic profiling. Preliminary functional assessment of a gene, interleukin-6 (IL-6), highly upregulated in cisplatin-treated cells was carried out using clonogenicity and tumorigenicity assays. We show that cisplatin-induced IL-6 expression can contribute to the increase in tumorigenic potential of head and neck cancer cells but does not contribute to cisplatin resistance. Finally, through clonal analysis, we show that cisplatin-induced IL-6 expression and cisplatin-induced tumorigenicity are stochastically derived. We report that cisplatin treatment of head and neck cancer cells results in a transient accumulation of cisplatin-resistant, small, and IL-6-positive cells that are highly tumorigenic. These data also suggest that therapies that reduce IL-6 action may reduce recurrence rates and/or increase disease-free survival times in head and neck cancer patients, and thus, IL-6 represents a promising new target in HNSCC treatment., ((c) 2010 AACR.)

Purpose: The standard of care for ovarian cancer includes platinum-based chemotherapy. It is not possible, however, to predict clinical platinum sensitivity or to design rational strategies to overcome resistance. We used a novel approach to identify altered gene expression associated with high sensitivity to cisplatin, to define novel targets to sensitize tumor cells to platins and ultimately improve the effectiveness of this widely used class of chemotherapeutics., Experimental Design: Using differential display PCR, we identified genes differentially expressed in a mutagenized cell line with unusual sensitivity to cisplatin. The most highly differentially expressed gene was selected, and its role in determining cisplatin sensitivity was validated by gene transfection and small interfering RNA (siRNA) approaches, by association of expression levels with cisplatin sensitivity in cell lines, and by association of tumor expression levels with survival in a retrospective cohort of 71 patients with serous ovarian adenocarcinoma., Results: The most highly differently expressed gene identified was ANKRD1, ankyrin repeat domain 1 (cardiac muscle). ANKRD1 mRNA levels were correlated with platinum sensitivity in cell lines, and most significantly, decreasing ANKRD1 using siRNA increased cisplatin sensitivity >2-fold. ANKRD1 was expressed in the majority of ovarian adenocarcinomas tested (62/71, 87%), and higher tumor levels of ANKRD1 were found in patients with worse outcome (overall survival, P=0.013)., Conclusions: These findings suggest that ANKRD1, a gene not previously associated with ovarian cancer or with response to chemotherapy, is associated with treatment outcome, and decreasing ANKRD1 expression, or function, is a potential strategy to sensitize tumors to platinum-based drugs.

Objective: The ABC transporter MRP2 (ABCC2) can mediate cisplatin efflux, and over-expression of MRP2 has been associated with cisplatin resistance in cancer cell lines. The aim of this study was to determine the role of MRP2 in modulating cisplatin cytotoxicity in normal cells as well as the relationship between MRP2 expression and clinical response to platinum-based agents in ovarian cancer., Methods: The effect of absence of MRP2 expression on cisplatin sensitivity was investigated using primary hepatocyte cultures from the TR- rat strain, which is deficient in Mrp2. We also examined MRP2 expression immunohistochemically in human ovarian tumors exhibiting extremes of clinical response to platinum-based chemotherapy, either absolute platin resistance or patients with residual disease after surgery who experienced extremely long complete response to primary platinum-based chemotherapy., Results: Primary hepatocyte cultures from Mrp2-deficient TR- rats were over threefold more sensitive to cisplatin and accumulated a twofold greater amount of platinum on DNA that wild-type rat hepatocytes. In human ovarian carcinomas, MRP2 was detected by immunohistochemistry in 3/13 (23%) tumors from patients with absolute platin resistance compared with 5/9 (56%) tumors from patients with prolonged survival following treatment including a platinum-based agent., Conclusion: These studies indicate that MRP2 may play an important role in modulating normal tissue response to cisplatin. However, MRP2 expression occurred only in a subset of primary ovarian cancers, was frequently aberrant in location and was not correlated with clinical response to platinum-based chemotherapy.

After more than two decades of extensive use, drugs based on platinum continue to have a major role in cancer treatment. Although systematic approaches to the development of new analogues have produced agents with less toxicity and novel mechanisms of action, to date such approaches have not achieved more cures than can be achieved with the parent compound, cisplatin. Greater gains might be expected from accumulating knowledge about what makes cancer cells sensitive or resistant to platinum-based chemotherapy. Recent information on drug-efflux pathways, including expression of multidrug-resistance protein 2, and on how tumour cells behave when their DNA is distorted by a platinum adduct, suggests new avenues for translational research. The prospects include modulation of cellular handling of platinum compounds and individualised therapy based on expression of molecules that determine platinum sensitivity. [Copyright &y& Elsevier]