Lisa M. Schumaker

Racial Survival Disparity in Head and Neck Cancer Results from Low Prevalence of Human Papillomavirus Infection in Black Oropharyngeal Cancer Patients

The burden of squamous cell carcinoma of the head and neck (SCCHN) is greater for blacks than for whites, especially in oropharyngeal cases. We previously showed retrospectively that disease-free survival was significantly greater in white than in black SCCHN patients treated with chemoradiation, the greatest difference occurring in the oropharyngeal subgroup. Oropharyngeal cancer is increasing in incidence and in its association with human papillomavirus (HPV) infection; HPV-positive oropharyngeal cancer patients have significantly better outcomes (versus HPV-negative). These collective data led to the present analyses of overall survival (OS) in our retrospective cohort and of OS and HPV status (tested prospectively in pretreatment biopsy specimens) in the phase 3, multicenter TAX 324 trial of induction chemotherapy followed by concurrent chemoradiation in SCCHN patients. Median OS in the retrospective cohort of 106 white and 95 black SCCHN patients was 52.1 months (white) versus only 23.7 months (black; P = 0.009), due entirely to OS in the subgroup of patients with oropharyngeal cancer—69.4 months (whites) versus 25.2 months (blacks; P = 0.0006); no significant difference by race occurred in survival of non-oropharyngeal SCCHN (P = 0.58). In TAX 324, 196 white patients and 28 black patients could be assessed for HPV status. Median OS was significantly worse for black patients (20.9 months) than for white patients (70.6 months; P = 0.03) and dramatically improved in HPV-positive (not reached) versus HPV-negative (26.6 months, 5.1 hazard ratio) oropharyngeal patients (P < 0.0001), 49% of whom were HPV-16 positive. Overall, HPV positivity was 34% in white versus 4% in black patients (P = 0.0004). Survival was similar for black and white HPV-negative patients (P = 0.56). This is the first prospective assessment of confirmed HPV status in black versus white SCCHN patients. Worse OS for black SCCHN patients was driven by oropharyngeal cancer outcomes, and that for black oropharyngeal cancer patients by a lower prevalence of HPV infection. These findings have important implications for the etiology, prevention, prognosis, and treatment of SCCHN.

Cisplatin Preferentially Binds Mitochondrial DNA and Voltage-Dependent Anion Channel Protein in the Mitochondrial Membrane of Head and Neck Squamous Cell Carcinoma: Possible Role in Apoptosis

Purpose: Cisplatin adducts to nuclear DNA (nDNA) are felt to be the molecular lesions that trigger apoptosis, but the mechanism linking nDNA adduct formation and cell death is unclear. Some literature in the last decade has suggested a possible direct effect of cisplatin on mitochondria independent of nDNA interaction. In this study, we define separately the sequelae of cisplatin interactions with nDNA and with mitochondria in head and neck squamous cell carcinoma (HNSCC) cell lines. Experimental Design: Cisplatin binding to mitochondrial DNA (mtDNA) and proteins was analyzed by atomic absorption spectroscopy and other methods. Results: Following 1 hour of exposure to cisplatin, platinum adducts to mtDNA were 300- to 500-fold more abundant than adducts to nDNA; these differences were not due to differences in rates of adduct repair. Whereas HNSCC cell cytoplasts free of nDNA retained the same dose-dependent cisplatin sensitivity as parental cells, HNSCC ρ0 cells free of mtDNA were 4- to 5-fold more resistant to cisplatin than parental cells. Isolated mitochondria released cytochrome c within minutes of exposure to cisplatin, and ultrastructural analysis of intact HNSCC cells by electron microscopy showed marked mitochondrial disruption after 4 hours of cisplatin treatment, whereas the nucleus and other cellular structures remain intact. The very prompt release of cytochrome c from isolated mitochondria implies that apoptosis does not require alteration in mitochondrial gene transcription. Further, cisplatin binds preferentially to mitochondrial membrane proteins, particularly the voltage-dependent anion channel. Conclusions: Cisplatin binding to nDNA is not necessary for induction of apoptosis in HNSCC, which can result from direct action of cisplatin on mitochondria.

The mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R), a putative breast tumor suppressor gene

Loss of heterozygosity (LOH) at the mannose 6-phosphate/insulin-like growth factor 2 receptor gene locus (M6P/IGF2R) on 6q26-27 has recently been demonstrated in approximately 30% of both invasive and in situ breast cancers. LOH was coupled with somatic point mutations in the remaining allele in several instances, leading to the proposition that M6P/IGF2R is a tumor suppressor gene [1]. Somatic mutations in M6P/IGF2R have also been described in hepatoma [2] and gastrointestinal cancers with the replication error positive (RER+) phenotype [3]. These data indicate that M6P/IGF2R loss of function mutations may be involved in the pathogenesis of a wide spectrum of malignancies. Extensive data on the normal function of the M6P/IGF2R suggest that loss of M6P/IGF2R activity may contribute to multiple aspects of tumor pathophysiology, including deregulated growth, apoptosis, angiogenesis and invasion.

The effect of extracellular calcium on colonocytes: evidence for differential responsiveness based upon degree of cell differentiation

Calcium supplementation decreases the incidence of colon cancer in animal models and may prevent colon cancer in man. Potential mechanisms include binding of mitogens and direct effects of calcium on colonic epithelial cells. In this study, the effects of extracellular calcium on epithelial cell growth and differentiation were studied in three colon carcinoma and two colonic adenoma cell lines. The characteristics studied included morphology, cell cycle kinetics, [Ca2+]IC (intracellular calcium concentration), proliferation, and expression of differentiation markers such as carcinoembryonic antigen (CEA) and alkaline phosphatase (AP). Sodium butyrate (NaB) and 1,25‐dihydroxyvitamin D3 were used as controls in the latter three assays as these two agents are known differentiating agents. Alteration of [Ca+2]EC (extracellular calcium concentration) did not affect carcinoembryonic antigen (CEA) or alkaline phosphatase (AP) expression. NaB enhanced the expression of AP three‐fold and CEA five‐fold. This effect was augmented by increasing [Ca2+]EC. The exposure of cells to 1,25‐(OH)2‐Vitamin D3 increased CEA but not AP. [Ca2+]IC increased in response to 1,25‐(OH)2‐vitamin D3 and NaB but not with variation in [Ca2+]EC. Increased [Ca2+]EC inhibited proliferation of well‐differentiated cells, but had no effect on poorly‐differentiated cells. Morphological studies showed that extracellular calcium was necessary for normal cell—cell interactions.

Mannose 6-Phosphate/Insulin-Like Growth Factor 2 Receptor, a Bona Fide Tumor Suppressor Gene or Just a Promising Candidate?

The mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R)3 is considereda “candidate” tumor suppressor gene. This hypothesis has been provoked by the identificationof loss of heterozygosity (LOH) at the M6P/IGF2R locus on chromosome 6q26 in breast andliver cancer, accompanied by point mutations in the remaining allele. Somatic mutations incoding region microsatellites have also been described in replication error positive (RER+)tumors of the gastrointestinal tract, endometrium and brain. These genetic data are compelling,but a tumor suppressor gene candidate has to meet functional as well as genetic criteria. Thisreview weighs the evidence and discusses the observations that are necessary to promoteM6P/IGF2R from candidate to bona fide tumor suppressor gene.

Correlation of p16 expression and HPV type with survival in oropharyngeal squamous cell cancer

OBJECTIVES Examine the effect of concordance between p16 overexpression and HR (high risk) HPV DNA status on overall survival in a large series of oropharyngeal squamous cell carcinoma (OPSCC) cases. MATERIALS AND METHODS A total of 185 patients with primary OPSCC had genomic DNA tested by PCR for the HPV16 E6 and E7 oncogenes. 184 of 185 patients had p16 IHC performed. Linear array HPV genotyping was performed in all 21 HPV16/p16 discordant cases (HPV16+/p16- or HPV16-/p16+) as well as in 43 control cases. RESULTS 73 of 185 patients were positive for HR HPV (39%). Six of 73 HPV infections were due to HR HPV types other than HPV16: types 31 (1), 33 (2), 51 (1), 58 (1), and 59 (1); all 6 cases were p16 positive. p16 IHC was concordant with HR HPV testing in 169 of 184 cases (92%), and had a sensitivity and specificity of 92% and 92%. HR HPV+/p16+ and discordant HR HPV/p16 patients had significantly improved overall survival compared to HR HPV-/p16- patients. CONCLUSION p16 IHC is a reliable surrogate marker for HR HPV testing in OPSCC. Prognostically favorable HR HPV genotypes other than HPV16 are reflected in p16 positivity.

Estrogen receptor expression and sensitivity to paclitaxel in breast cancer.

A retrospective analysis of CALGB trial 9344 suggested paclitaxel administration following cyclophosphamide and doxorubicin adjuvant chemotherapy is most beneficial for patients with ER? negative (ER?-) breast cancer. Since the cytotoxic effects of paclitaxel are cell cycle dependent, we postulated that the relationship between ER? and the effectiveness of adjuvant paclitaxel reflects the observation that ER? positive (ER?+) breast cancers proliferate more slowly than ER?- breast cancers. Three in vitro models (MCF-7, T47D and ZR-75) were examined to compare growth rates and paclitaxel-induced apoptosis in ER?+ and ER?- clones of the same, originally ER?+ cell line. For the T47D and ZR-75 cell lines, loss of ER? was associated with a decrease in doubling time and an increase in paclitaxel sensitivity. However, when cell culture conditions were altered to achieve equivalent cell proliferation rates, no difference in paclitaxel sensitivity was observed. Similarly, an ER?- clone of MCF-7 cells that did not exhibit an enhanced growth rate compared to its ER?+ counterpart also did not show increased paclitaxel sensitivity. The combined apoptotic effects of tamoxifen and paclitaxel on MCF-7 cells were not synergistic or even clearly additive. In these in vitro models, the effectiveness of paclitaxel correlated more closely with growth rate than ER? expression. These data suggest that measurements of tumor proliferation may provide more accurate predictive markers for the benefits of adjuvant paclitaxel than ER? analysis.

Novel biomarker panel predicts prognosis in human papillomavirus-negative oropharyngeal cancer: an analysis of the TAX 324 trial.

New treatment strategies for locally advanced head and neck squamous cell carcinoma combine induction chemotherapy and chemoradiation. Identifying the predictors of outcome in sequentially treated patients is critical for focusing therapeutic research. In this analysis, the authors evaluated human papillomavirus type 16 (HPV‐16) status and the expression levels of a defined set of biomarkers to identify predictors of response to this treatment modality.

Novel biomarker panel predicts prognosis in human papillomavirus-negative oropharyngeal cancer

New treatment strategies for locally advanced head and neck squamous cell carcinoma combine induction chemotherapy and chemoradiation. Identifying the predictors of outcome in sequentially treated patients is critical for focusing therapeutic research. In this analysis, the authors evaluated human papillomavirus type 16 (HPV‐16) status and the expression levels of a defined set of biomarkers to identify predictors of response to this treatment modality.

Emergence of HPV16-positive oropharyngeal cancer in Black patients over time: University of Maryland 1992-2007.

While we previously reported a striking racial difference in the prevalence of human papilloma virus (HPV)–positive squamous cell carcinoma of the oropharynx (OPSCC), less is known about differences in outcomes and trends over time in OPSCC by HPV status and race. We conducted a retrospective analysis of 467 patients with OPSCC treated at the University of Maryland Greenebaum Cancer Center (Baltimore, MD) between 1992 and 2007, of which 200 had tissue available for HPV16 testing. HPV16-positive patients were significantly more likely to be white, with 45.5% of whites and 15.5% of blacks testing positive for HPV16. There was a significant increase in HPV16-positive OPSCC for all patients over time from 15.6% in 1992 to 1995 to 43.3% in 2004 to 2007 (P = 0.01). From 1992 to 1995, 33% of white patients were HPV16-positive, with no black patients positive. From 2004 to 2007, 17.7% of black patients and 54% of white patients were HPV16-positive. White and black patients with HPV16-positive tumors had an identical and favorable overall survival (OS; median, 8.1 and 8.1 years, respectively). However, among HPV16-negative patients, whites had an improved OS compared with blacks (median, 2.3 vs. 0.9 years, respectively; P = 0.02), including when analyzed in a multivariable Cox regression model. From 1992 to 2007, the percentage of HPV16-positive OPSCC increased for white patients and was seen for the first time in black patients. While survival for HPV-positive black and white patients was similar and favorable, outcomes for HPV-negative patients were poor, with blacks having worse survival even after controlling for baseline characteristics.Cancer Prev Res; 8(1); 12–19. ©2014 AACR. See related article by E. Cohen and C. Fakhry, p. 9