Increased placenta growth factor mRNA level is significantly associated with progression, recurrence and poor prognosis of oral squamous cell carcinoma

Background/PurposeExpression of placenta growth factor (PlGF) mRNA is shown to correlate with the progression and prognosis of several human cancers. In this study, we assessed whether the PlGF mRNA level in oral squamous cell carcinoma (OSCC) tissue could be used to predict the progression and prognosis of OSCCs in Taiwan.MethodsThis study used quantitative real-time reverse transcription-polymerase chain reaction (quantitative RT-PCR) to detect the PlGF mRNA levels in 63 paired OSCC and adjacent normal-looking oral mucosa (non-OSCC) tissues. Threshold cycle (CT) was defined as the PCR cycle number needed to generate a pre-determined amount of DNA (threshold). For a chosen threshold, a smaller starting copy number of mRNA results in a higher CT value. In this study, the relative expression level of tissue PlGF mRNA in each OSCC patients was expressed as −ΔCT = −(OSCC CT – non-OSCC CT). Thus, the higher the −ΔCT, the greater the copy number of PlGF mRNA in tissues.ResultsWe found that the higher mean PlGF mRNA −ΔCT value was significantly associated with OSCCs with larger tumor size (p = 0.03), positive lymph node metastasis (p = 0.003), more advanced clinical stages (p = 0.013) or the presence of loco-regional recurrence (p = 0.039). Positive lymph node metastasis (p = 0.019) and PlGF mRNA −ΔCT value >2 (p = 0.016) were identified as two independent unfavorable prognosis factors by multivariate analyses with Cox regression model. Moreover, Kaplan-Meier curve showed that OSCC patients with a PlGF mRNA −ΔCT value >2 had a significantly poorer recurrence-free survival than those with a PlGF mRNA −ΔCT value ≤2 (log-rank test, p = 0.017).ConclusionThe OSCC tissue PlGF mRNA level can be used to predict the progression and prognosis of OSCCs in Taiwan.