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Year : 2015  |  Volume : 7  |  Issue : 5  |  Page : 173-175  

Circulating tumor cells in oral squamous cell carcinoma-an enigma or reality?

Department of Oral and Maxillofacial Pathology, Sree Balaji Dental College and Hospital, Bharath University, Pallikaranai, Chennai, India

Date of Submission31-Oct-2014
Date of Decision31-Oct-2014
Date of Acceptance09-Nov-2014
Date of Web Publication30-Apr-2015

Correspondence Address:
Dr. N Anitha
Department of Oral and Maxillofacial Pathology, Sree Balaji Dental College and Hospital, Bharath University, Pallikaranai, Chennai
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0975-7406.155893

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Oral squamous cell carcinoma (OSCC) is ranking 1 st among males and 4 th among females in India. In spite of major advances in diagnosis and treatment of OSCC, survival rates, have remained poor. Circulating tumor cells (CTCs) in the blood stream, play an important role in establishing metastases. It is important to identify patients suffering from nonlocalized tumor with "circulating" tumor cells to determine the tailor made, systemic therapy in addition to local resection and irradiation. Thus, detecting metastases at an early stage are needed for better prognosis and survival. CTCs as new prognostic marker to detect the metastatic potential will provide a novel insight into tumor burden and efficacy of therapy. The recent advances and its application in OSCC will be reviewed.

Keywords: Circulating tumor cells, oral squamous cell carcinoma, prognostic marker

How to cite this article:
Anitha N, Jimson S, Masthan K, Jacobina J J. Circulating tumor cells in oral squamous cell carcinoma-an enigma or reality?. J Pharm Bioall Sci 2015;7, Suppl S1:173-5

How to cite this URL:
Anitha N, Jimson S, Masthan K, Jacobina J J. Circulating tumor cells in oral squamous cell carcinoma-an enigma or reality?. J Pharm Bioall Sci [serial online] 2015 [cited 2022 Aug 17];7, Suppl S1:173-5. Available from:

Circulating tumor cells (CTCs) that play a pivotal role in establishing metastases serve as biomarkers for diagnosis, treatment and prognosis of cancer. Death in more than 90% of cancer patients is found to be due to metastasis. [1] Cancer cells are said to be detected in circulation even before the presentation of clinical symptoms. [2] CTCs were reported to be present about 140 years ago. [3]

CellSearch system (Veridex, Raritan, NJ, USA) was introduced in 2004. It is the only device cleared by Food and Drug Administration (FDA) for selecting and enumerating CTCs. [4]

In patients with oral squamous cell carcinoma (OSCC), CTCs are regarded as prognostic markers for the disease - free survival. [5] In the peripheral blood, CTCs are extremely rare events, estimated to be around one cell among a hundred million or billion of circulating blood cells. [6] Thus, an enrichment step is mandatory for efficient detection of these cells.

   Development of Metastasis via Circulating Tumour Cells Top

Epithelial-to-mesenchymal transition occurs when the tumor cells and clusters that are shed from the primary tumor intravasate into circulation. Apoptosis and necrosis kills a majority of CTCs, releasing debris, fragments of cells and intracellular elements (circulating tumor material and ctDNA). Circulating tumor microemboli (CTM) that are clusters of tumor cells, as a result of the collision may release the tumor cells. The CTCs then extravasate, leading to metastasis [Figure 1]. [7]
Figure 1: Development of metastases via circulating tumor cells

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   Circulating Tumor Cells Assays Top

  • Involves an initial enrichment step, where tumor cells are isolated following depletion of blood cells
  • The tumor cells are stained or oncogene probed: The CTCs are labeled by antibodies or aptamers or probed by DNA primers
  • Tumor cell detection via cytometry, microscopy, conductometry, fiber-optics, reverse transcription- polymerase chain reaction (RT-PCR), fluorescence in situ hybridization and comparative genomic hybridization.

The enrichment methods depend on physical characteristics like size, density or dielectrophoretic mobility that exemplifies CTCs or by the expression of certain surface molecules that are captured by magnetic bead-coated antibodies. Gradient centrifugation is commonly done using ficoll-hypaque that uses density of different cell types. A substantial loss of cell material is however said to occur during enrichment. [8] Monoclonal antibodies are available against different epithelial proteins, namely cytoskeleton keratins, surface adhesion molecules or growth factor receptors.

One of the most advanced methods for detecting and enumerating CTCs from peripheral blood is by the CellSearch system (Veridex, Raritan, NJ, United States) that enriches and immunostains CTCs. It is the first FDA-cleared device for CTC detection in solid tumors and for metastasized prostate, colon, and breast cancers. [9],[10],[11],[12],[13] Gröbe et al. detected CTCs in a small number of OSCC patients. [5] The EpCAM positive tumor cells are separated by immunomagnetic bead separation and are immunofluorescent stained with anti-keratin antibodies. The leukocytes are excluded using anti-CD45-antibody. Under fluorescent microscope, nucleated cells with a diameter of 4 μm, keratin positive and CD45 negative are accepted as tumor cells. [14]

Other recently developed EpCAM-based tools include:

  • Microfluid-based CTC-chips [15]
  • Surface enhanced Raman spectroscopy with epidermal growth factor receptors as targeting ligand [16]
  • Detection of CTCs after the leukapheresis. [17]

   In Vivo Detection of Circulating Tumour Cells Top

GILUPI cell collector device consisting of a wire coated with anti-EpCAM antibodies that collects CTCs when inserted into a vein for 30 min. Presence of CTCs and exclusion of leukocytes are confirmed with anti-keratin and ant-CD45 antibodies. [18]

   Epithelial Immunospots Top

Involves detection of viable CTCs after a 48 h culture, where leukocytes are depleted by negative selection using CD45. [19]

   Molecular Technologies Top

They involve PCR amplification based on either DNA or complementary DNA (messenger RNA). RT-PCR approaches use epithelium-specific targets, like keratin 19 encoding targets. [20]

   Recent Trends in Circulating Tumour Cells Research Top

Detecting circulating tumor microemboli

A collective migration of tumor cells leads to the formation of CTM. [21] These collective tumor cells intravasate through leaky blood vessel. [22] CTMs exhibit a highly variable morphology: As clusters, circles or strands. [23]

The likely cause of CTM formation is increased adhesiveness of circulating tumor cells. [24]

Studies indicate CTM presence indicates higher metastatic potential. [25] The suggested explanations are as follows:

  • CTMs are easily caught in narrow vessels than CTCs [26]
  • CTMs provide a favorable environment for survival of tumor cells [24]
  • EGF and VEGF stimulate proliferation and inhibit apoptosis. [27]

Circulating tumor microemboli detection is done using flow cytometry [28] or by cell search.

Circulating tumor cells detection based on telomerase activity

As telomerase activity inactivated in cancer [29] and since tumor cells lose epithelial markers during metastasis, assessing telomerase activity would provide valuable information on CTCs. Since the whole blood sample has to be lysed to measure enzyme activity, CTCs get destroyed, which is a downside for the method.

Circulating tumor cells detection by aptamer technology

Aptamers are single-stranded DNA or RNA molecules. [30] Systemic evaluation of ligands by exponential enrichment automates aptamer production. [31]

   Conclusion Top

With the advent of new technologies to detect CTCs current staging methods of cancer have been refined. Additional treatment options can now be made available for patients suffering from OSCC as collecting samples from peripheral blood is invasive. Tumor cells that undergo an epithelial-to-mesenchymal transition show downregulation of epithelial features. Hence, molecular analysis of CTCs is required. Advances have been made with aptamers and microdevices that minimize technical constraints. CTCs have to be evaluated by proteomics and genomics too.

   References Top

Wicha MS, Hayes DF. Circulating tumor cells: Not all detected cells are bad and not all bad cells are detected. J Clin Oncol 2011;29:1508-11.  Back to cited text no. 1
Rao GC, Larson C, Repollet M, Rutner H, Terstappen LW, Chara SM. Analysis of circulating tumor cells, fragments and debris. United States Patent. 7863012; 2011.  Back to cited text no. 2
Asworth TR. A case of cancer in which cancer cells similar to those in tumors were seen in the blood after death. Aust Med J 1869;14:146-9.  Back to cited text no. 3
Mostert B, Sleijfer S, Foekens JA, Gratama JW. Circulating tumor cells (CTCs): Detection methods and their clinical relevance in breast cancer. Cancer Treat Rev 2009;35:463-74.  Back to cited text no. 4
Gröbe A, Blessmann M, Hanken H, Friedrich RE, Schön G, Wikner J, et al. Prognostic relevance of circulating tumor cells in blood and disseminated tumor cells in bone marrow of patients with squamous cell carcinoma of the oral cavity. Clin Cancer Res 2014;20:425-33.  Back to cited text no. 5
Ross AA, Cooper BW, Lazarus HM, Mackay W, Moss TJ, Ciobanu N, et al. Detection and viability of tumor cells in peripheral blood stem cell collections from breast cancer patients using immunocytochemical and clonogenic assay techniques. Blood 1993;82:2605-10.  Back to cited text no. 6
Hong B, Zu Y. Detecting circulating tumor cells: Current challenges and new trends. Theranostics 2013;3:377-94.  Back to cited text no. 7
Borgen E, Naume B, Nesland JM, Kvalheim G, Beiske K, Fodstad O, et al. Standardization of the immunocytochemical detection of cancer cells in BM and blood: I. establishment of objective criteria for the evaluation of immunostained cells. Cytotherapy 1999;1:377-88.  Back to cited text no. 8
Shaffer DR, Leversha MA, Danila DC, Lin O, Gonzalez-Espinoza R, Gu B, et al. Circulating tumor cell analysis in patients with progressive castration-resistant prostate cancer. Clin Cancer Res 2007;13:2023-9.  Back to cited text no. 9
Hayes DF, Cristofanilli M, Budd GT, Ellis MJ, Stopeck A, Miller MC, et al. Circulating tumor cells at each follow-up time point during therapy of metastatic breast cancer patients predict progression-free and overall survival. Clin Cancer Res 2006;12:4218-24.  Back to cited text no. 10
Riethdorf S, Fritsche H, Müller V, Rau T, Schindlbeck C, Rack B, et al. Detection of circulating tumor cells in peripheral blood of patients with metastatic breast cancer: A validation study of the CellSearch system. Clin Cancer Res 2007;13:920-8.  Back to cited text no. 11
Sastre J, Maestro ML, Puente J, Veganzones S, Alfonso R, Rafael S, et al. Circulating tumor cells in colorectal cancer: Correlation with clinical and pathological variables. Ann Oncol 2008;19:935-8.  Back to cited text no. 12
Gorges TM, Pantel K. Circulating tumor cells as therapy-related biomarkers in cancer patients. Cancer Immunol Immunother 2013;62:931-9.  Back to cited text no. 13
Cristofanilli M, Budd GT, Ellis MJ, Stopeck A, Matera J, Miller MC, et al. Circulating tumor cells, disease progression, and survival in metastatic breast cancer. N Engl J Med 2004;351:781-91.  Back to cited text no. 14
Nagrath S, Sequist LV, Maheswaran S, Bell DW, Irimia D, Ulkus L, et al. Isolation of rare circulating tumour cells in cancer patients by microchip technology. Nature 2007;450:1235-9.  Back to cited text no. 15
Wang X, Qian X, Beitler JJ, Chen ZG, Khuri FR, Lewis MM, et al. Detection of circulating tumor cells in human peripheral blood using surface-enhanced Raman scattering nanoparticles. Cancer Res 2011;71:1526-32.  Back to cited text no. 16
Eifler RL, Lind J, Falkenhagen D, Weber V, Fischer MB, Zeillinger R. Enrichment of circulating tumor cells from a large blood volume using leukapheresis and elutriation: Proof of concept. Cytometry B Clin Cytom 2011;80:100-11.  Back to cited text no. 17
Saucedo-Zeni N, Mewes S, Niestroj R, Gasiorowski L, Murawa D, Nowaczyk P, et al. A novel method for the in vivo isolation of circulating tumor cells from peripheral blood of cancer patients using a functionalized and structured medical wire. Int J Oncol 2012;41:1241-50.  Back to cited text no. 18
Alix-Panabières C, Vendrell JP, Pellé O, Rebillard X, Riethdorf S, Müller V, et al. Detection and characterization of putative metastatic precursor cells in cancer patients. Clin Chem 2007;53:537-9.  Back to cited text no. 19
Pantel K, Brakenhoff RH, Brandt B. Detection, clinical relevance and specific biological properties of disseminating tumour cells. Nat Rev Cancer 2008;8:329-40.  Back to cited text no. 20
Friedl P, Wolf K. Tumour-cell invasion and migration: Diversity and escape mechanisms. Nat Rev Cancer 2003;3:362-74.  Back to cited text no. 21
Christiansen JJ, Rajasekaran AK. Reassessing epithelial to mesenchymal transition as a prerequisite for carcinoma invasion and metastasis. Cancer Res 2006;66:8319-26.  Back to cited text no. 22
Stott SL, Hsu CH, Tsukrov DI, Yu M, Miyamoto DT, Waltman BA, et al. Isolation of circulating tumor cells using a microvortex-generating herringbone-chip. Proc Natl Acad Sci U S A 2010;107:18392-7.  Back to cited text no. 23
Hou JM, Krebs M, Ward T, Sloane R, Priest L, Hughes A, et al. Circulating tumor cells as a window on metastasis biology in lung cancer. Am J Pathol 2011;178:989-96.  Back to cited text no. 24
Brandt B, Junker R, Griwatz C, Heidl S, Brinkmann O, Semjonow A, et al. Isolation of prostate-derived single cells and cell clusters from human peripheral blood. Cancer Res 1996;56:4556-61.  Back to cited text no. 25
Liotta LA, Saidel MG, Kleinerman J. The significance of hematogenous tumor cell clumps in the metastatic process. Cancer Res 1976;36:889-94.  Back to cited text no. 26
Zhang X, Nie D, Chakrabarty S. Growth factors in tumor microenvironment. Front Biosci (Landmark Ed) 2010;15:151-65.  Back to cited text no. 27
Takao M, Takeda K. Enumeration, characterization, and collection of intact circulating tumor cells by cross contamination-free flow cytometry. Cytometry A 2011;79:107-17.  Back to cited text no. 28
Blackburn EH. Telomere states and cell fates. Nature 2000;408:53-6.  Back to cited text no. 29
Xu Y, Yang X, Wang E. Review: Aptamers in microfluidic chips. Anal Chim Acta 2010;683:12-20.  Back to cited text no. 30
Tuerk C, Gold L. Systematic evolution of ligands by exponential enrichment: RNA ligands to bacteriophage T4 DNA polymerase. Science 1990;249:505-10.  Back to cited text no. 31


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