Elevated growth differentiating factor 15 expression predicts long-term benefit of docetaxel, cisplatin and 5-fluorouracil induction chemotherapy in patients with oral cancer

Growth differentiation factor 15 (GDF15) in cancer cell metastasis: from the cells to the patients

Growth differentiation factor 15 (GDF15), a member of the transforming growth factor β superfamily, has been postulated to be implicated in cancer cell metastasis although its role has not been fully elucidated yet. The purpose of this review is to clarify the role of GDF-15 in cancer cell metastasis based on current advances in the field. The studies were divided into those involving evaluation of GDF15 expression in the serum or tissue of cancer patients, and those involving in vitro experiments in cancer cell lines or in vivo experiments in animal models. GDF15 was shown to be elevated in the serum or tissues of cancer patients with its expression being correlated with decreased survival. Moreover, most in vitro and in vivo studies also corroborated a metastasis-promoting role for GDF15. However, there were a few studies, where GDF15 was shown to suppress the metastatic properties of cells. As, GDF15 has been known for its pleiotropic effects, it is not surprising to behave differently in different types of cancer. Thus, GDF15 has the potential of not only being a useful metastasis biomarker, but also a promising therapeutic target against cancer cell metastasis in many cancer types.

Characterisation of a subpopulation of CD133+ cancer stem cells from Chinese patients with oral squamous cell carcinoma

Cancer stem cells (CSCs) play a critical role in cancer development and growth. The aim of this study was to identify and isolate CSCs from populations of primary oral squamous cell carcinoma (OSCC) cells, which were obtained from OSCC specimens and identified by cell morphology and immunohistochemical staining for keratin. CD133⁺ cells detected by flow cytometry comprised 0.41 ± 0.06% of primary OSCC cells and were isolated from primary OSCC cell populations using magnetic-activated cell sorting, revealing that 93.39% of high-purity CD133⁺ cells were in the G0/G1 phase of the cell cycle. Additionally, the growth rate of CD133⁺ cells was higher than that of CD133⁻ cells, and in vivo tumourigenesis experiments showed that the tumourigenic ability of CD133⁺ cells was markedly stronger than that of CD133⁻ cells. Moreover, CD133⁺ cells showed increased chemotherapeutic resistance to cisplatin and higher self-renewal ability according to sphere-formation assay, as well as higher mRNA levels of stemness-associated genes, including NANOG, SOX2, ALDH1A1, and OCT4. These results indicated that OSCC cells, which share certain characteristics of CSCs, harbour CD133⁺ cells potentially responsible for OSCC aggressiveness, suggesting CD133 as a potential prognostic marker and therapeutic target.

DSPP-MMP20 gene silencing downregulates cancer stem cell markers in human oral cancer cells

BACKGROUND

Recent findings indicate that dentin sialophosphoprotein (DSPP) and matrix metalloproteinase (MMP) 20 interact in oral squamous cell carcinoma (OSCC). The objective of this study was to determine the effects of DSPP/MMP20 gene silencing on oral cancer stem cell (OCSC) markers.

METHODS

The expression of well-established OCSC markers: ABCG2; ALDH1; CD133; CD44; BMI1; LGR4, and Podoplanin in DSPP/MMP20-silenced OSCC cell line, OSC2, and controls were assayed by western blot (WB), and flow cytometry techniques. The sensitivity of OSC2 cells to cisplatin following DSPP/MMP20 silencing was also determined.

RESULTS

DSPP/MMP20 silencing resulted in downregulation of OCSC markers, more profoundly ABCG2 (84%) and CD44 (81%), following double silencing. Furthermore, while treatment of parent (pre-silenced) OSC2 cells with cisplatin resulted in upregulation of OCSC markers, DSPP/MMP20-silenced OSC2 cells similarly treated resulted in profound downregulation of OCSC markers (72 to 94% at 50 μM of cisplatin), and a marked reduction in the proportion of ABCG2 and ALDH1 positive cells (~ 1%).

CONCLUSIONS

We conclude that the downregulation of OCSC markers may signal a reduction in OCSC population following MMP20/DSPP silencing in OSCC cells, while also increasing their sensitivity to cisplatin. Thus, our findings suggest a potential role for DSPP and MMP20 in sustaining OCSC population in OSCCs, possibly, through mechanism(s) that alter OCSC sensitivity to treatment with chemotherapeutic agents such as cisplatin.

Overexpression of retinoblastoma‑binding protein 4 contributes to the radiosensitivity of AGS gastric cancer cells via phosphoinositide3‑kinase/protein kinase B pathway suppression

In the present study, the effects and underlying mechanism of RbAp48 on the radiosensitivity of AGS gastric cancer cells was investigated. Cell proliferation was determined with an MTT assay. Flow cytometry was performed to evaluate the cell cycle and apoptosis. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were performed to detect mRNA and protein expression, respectively, including RbAp48, phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt). The results revealed that radiation enhanced the expression level of RbAp48 in AGS cells, and that RbAp48 combined with radiation reduced AGS cell proliferation. In addition, RbAp48 combined with radiation resulted in G₂ phase arrest and induced apoptosis via regulation of the PI3K/Akt pathway. In conclusion, it was demonstrated that overexpression of RbAp48 enhanced the radiosensitivity of AGS gastric cancer cells via suppression of PI3K/Akt pathway activity, suggesting that RbAp48 may hold potential as a gene therapeutic strategy in the future, aiding in the treatment of gastric cancer.