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Articles by F. R Khuri
Total Records ( 5 ) for F. R Khuri
  A.R.M. R Amin , F. R Khuri , Z Chen and D. M. Shin

We have previously reported that the green tea polyphenol epigallocatechin-3-gallate (EGCG) and the epidermal growth factor receptor-tyrosine kinase inhibitor erlotinib had synergistic growth-inhibitory effects in cell culture and a nude mouse xenograft model of squamous cell carcinoma of the head and neck. However, the mechanism of their antitumor synergism is not fully understood. In the current study, we investigate the mechanism of their synergistic growth-inhibitory effects. The treatment of squamous cell carcinoma of the head and neck cell lines with erlotinib time-dependently increased the expression of cell cycle regulatory proteins p21 and p27 and apoptosis regulatory protein Bim. EGCG alone had very little or no effect on the expression of these proteins among the cell lines. However, simultaneous treatment with EGCG and erlotinib strongly inhibited erlotinib-induced expression of p21 and p27 without affecting the expression of Bim. Moreover, erlotinib increased the expression of p53 protein, the ablation of which by short hairpin RNA strongly inhibited EGCG- and erlotinib-mediated growth inhibition and the expression of p21, p27, and Bim. In addition, combined treatment with erlotinib and EGCG inhibited the protein level of p65 subunit of nuclear factor-B and its transcriptional target Bcl-2, but failed to do so in cells with ablated p53. Taken together, our results, for the first time, suggest that erlotinib treatment activates p53, which plays a critical role in synergistic growth inhibition by erlotinib and EGCG via inhibiting nuclear factor-B signaling pathway. Characterizing the underlying mechanisms of EGCG and erlotinib synergism will provide an important rationale for chemoprevention or treatment trials using this combination.

  X Wu , M. R Spitz , J. J Lee , S. M Lippman , Y Ye , H Yang , F. R Khuri , E Kim , J Gu , R Lotan and W. K. Hong

This study was aimed to identify novel susceptibility variants for second primary tumor (SPT) or recurrence in curatively treated early-stage head and neck squamous cell carcinoma (HNSCC) patients.

We constructed a custom chip containing a comprehensive panel of 9,645 chromosomal and mitochondrial single nucleotide polymorphisms (SNP) representing 998 cancer-related genes selected by a systematic prioritization schema. Using this chip, we genotyped 150 early-stage HNSCC patients with and 300 matched patients without SPT/recurrence from a prospectively conducted randomized trial and assessed the association of these SNPs with risk of SPT/recurrence.

Individually, six chromosomal SNPs and seven mitochondrial SNPs were significantly associated with risk of SPT/recurrence after adjustment for multiple comparisons. A strong gene-dosage effect was observed when these SNPs were combined, as evidenced by a progressively increasing SPT/recurrence risk as the number of unfavorable genotypes increased (P for trend < 1.00 x 10–20). Several polygenic analyses suggest an important role of interconnected functional network and gene-gene interaction in modulating SPT/recurrence. Furthermore, incorporation of these genetic markers into a multivariate model improved significantly the discriminatory ability over the models containing only clinical and epidemiologic variables.

This is the first large-scale systematic evaluation of germ-line genetic variants for their roles in HNSCC SPT/recurrence. The study identified several promising susceptibility loci and showed the cumulative effect of multiple risk loci in HNSCC SPT/recurrence. Furthermore, this study underscores the importance of incorporating germ-line genetic variation data with clinical and risk factor data in constructing prediction models for clinical outcomes.

  N. F Saba , M Choi , S Muller , H. J. C Shin , M Tighiouart , V. A Papadimitrakopoulou , A. K El Naggar , F. R Khuri , Z. G Chen and D. M. Shin

Inhibition of cyclooxygenase-2 (COX-2) pathways may have significant implications for the prevention and treatment of head and neck squamous cell carcinoma (HNSCC). COX-2 is overexpressed in both premalignant lesions and invasive HNSCC. We examined COX-2 expression by immunohistochemistry in normal tissues, different stages of premalignant lesions, and carcinoma in situ (CIS). We also evaluated the correlation between COX-2 expression and clinical characteristics of HNSCC patients. Tissue specimens were obtained from the following: premalignant lesions from 25 subjects enrolled in a biochemoprevention trial, tumor samples collected at diagnosis from 38 HNSCC patients enrolled in an induction chemotherapy trial, and normal control tissues from 10 noncancer, nonsmoking subjects. COX-2 was expressed in early and intermediate stages of premalignant lesions, increasing first in the basal and parabasal layers, then lower spinous, and upper spinous layers. This correlation was noted in normal epithelium (P < 0.0001), histologically normal in-field samples (P < 0.0001), low-grade dysplasia (P = 0.024), and moderate-grade dysplasia (P = 0.009), but was lost in the majority of high-grade dysplasia/CIS (P = 0.896). COX-2 expression was also noted to increase progressively through the early stages of premalignancy, and to decrease in severe/CIS stage and invasive carcinoma. COX-2 expression in tumors from patients treated with induction chemotherapy was correlated with overall survival after controlling for clinical variables. These findings elucidate the differential expression pattern of COX-2 in stages of head and neck premalignant lesions and invasive carcinoma, supporting the rationale for COX-2 inhibition as an important strategy for cancer chemoprevention. Further validation of COX-2 expression is needed in prospective ongoing chemoprevention trials.

  J Wang , S. M Lippman , J. J Lee , H Yang , F. R Khuri , E Kim , J Lin , D. W Chang , R Lotan , W. K Hong and X. Wu

Curatively treated patients with early-stage head and neck squamous cell carcinoma (HNSCC) are at high risks for second primary tumor (SPT) and recurrence. The regulator of G-protein signaling (RGS) is important in essential signaling transduction and cellular activities. We hypothesize that genetic variations of RGS may modulate the risk of SPT/recurrence in patients with early-stage HNSCC. In a nested case–control study, we evaluated 98 single-nucleotide polymorphisms (SNPs) in 17 RGS genes for the risk of SPT/recurrence among 450 HNSCC patients. Eight SNPs showed significant associations with the risk of SPT/recurrence, with the most significant one of rs2179653, which is located in the 5'-flanking region of RGS2 gene. Under a recessive genetic model, the homozygous variant genotype of this SNP was associated with 2.95-fold [95% confidence interval (CI): 1.52–5.74] increased risk of SPT/recurrence. This association remained significant after the adjustment for multiple comparisons. Cumulative effects analysis revealed that the risk increased significantly with the increasing numbers of unfavorable genotypes. Compared with subjects carrying 0–2 unfavorable genotypes, the hazard ratios (95% CIs) for those carrying 3 or 4+ were 1.73 (1.10–2.70) and 3.05 (1.92–4.83), respectively. Furthermore, survival tree analysis revealed potential higher order gene–gene interactions and indicated different outcomes based on distinct genotype profiles. Genetic variations of RGS genes may modulate the susceptibility to SPT/recurrence in early-stage HNSCC patients individually and cumulatively. Our results stressed the importance of taking a polygenic approach to evaluate the cumulative and interaction effects of genetic variations in the prediction of cancer risk and prognosis.

  X Zhang , H Yang , J. J Lee , E Kim , S. M Lippman , F. R Khuri , M. R Spitz , R Lotan , W. K Hong and X. Wu

Second primary tumor (SPT) and/or recurrence negatively impact the prognosis of patients with curatively treated early-stage head and neck cancer. MicroRNAs (miRNAs) play important roles in cancer development. We explored whether the variations of miRNA-related pathway were associated with the risk of SPT/recurrence in patients with early-stage head and neck cancer. This study includes 150 early-stage head and neck cancer patients with SPT/recurrence and 300 patients without SPT/recurrence. Two hundred and thirty-five tagging and potentially functional single-nucleotide polymorphisms (SNPs) were genotyped from eight miRNA biogenesis pathway genes and 135 miRNA-targeted genes. Eighteen miRNA-related SNPs were significantly associated with the risk of SPT/recurrence. The most significant SNP was rs3747238, a miRNA-binding site SNP in SMC1B. The variant homozygous genotype of this SNP was associated with a 1.74-fold increased risk [95% confidence interval (CI) 1.19–2.54; P = 0.004]. Cumulative effect analysis showed joint effects for the number of unfavorable genotype in patients. Survival tree analysis further identified the high-order gene–gene interactions and categorized the study subjects into low-, medium- and high-risk groups. Patients in the high-risk group had a 4.84-fold increased risk (95% CI: 3.11–7.51; P = 2.45 x 10–12) and a shorter event-free median survival time of 37.9 months (log rank P = 2.28 x 10–13). Our results suggested that miRNA-related genetic polymorphisms may be used individually and jointly to predict the risk of SPT/recurrence of early-stage head and neck cancer patients.

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