## 3 Results
### Short-Term and Long-Term Mortality and Senescence Effects of MMW Irradiation on H1299 Cancer Cells  
To examine whether MMW irradiation affects cell death and senescence, DAPI staining and \(\beta\)-galactosidase colorimetric assay were performed (Figures 4A and 5A) and the results summarized in Tables 5 and 6. Following MMW irradiation three different cell subgroups were observed: dead cells, senescent cells, and proliferating cells. Under the 2 min irradiation regime on the day of the irradiation (Day 1), approximately 14% of H1299 cells died after irradiation compared to only 4% of control cells (Figure 4B and Table 5). Under this exposure regime, dead cells further increased to almost 30% in the population over seven days of post irradiation incubation and was reduced to 3.4% by Day 14. H1299 Cells under 4 min irradiation showed about 14% mortality on Day 1, which decreased to 8% on Day 7 and reached around 10% by Day 14. H1299 cells exposed to 10 min irradiation showed mortality of almost 47% of the cell population on Day 1 and were completely dead before reaching Days 7 and 14 of the observation period. The results suggest that under the 2 min irradiation regime majority of the H1299 cell population avoid the immediate cytotoxic effect as energy dose is lower than the 4 min exposure regime but develop pro-apoptotic gates gradually. These cells die out over the next seven days of observation beyond which the cells that remain in the petri dish give rise to progeny devoid of any MMW treated effects on Day 14. Hence, the low mortality rate on Day 14 under the 2 min irradiation regime. In the case of 4 min exposure, mortality on Day 1 is much higher due to higher energy dosage. This allows only a small population of cells to continue proliferating into the subsequent 7-14 days period of observation; hence, a higher mortality on Day 14 for cells under the 4 min regime as compared to those under the 2 min duration. This conjecture is further supported by the observation of increased mortality associated with increasing the duration of exposure to 4 and 10 min which translates into higher dose delivery. \begin{table}
\begin{tabular}{c c c c} \hline
**Group** & **Day 1** & **Day 7** & **Day 14** \\ \hline
**Control** & 0.85 & 0.91 & 0.90 \\
**2 min** & 0.35 & 0.04 & 0.17 \\
**4 min** & \(-0.11\) & \(-0.2\) & \(-0.41\) \\
**10 min** & \(-0.35\) & - & - \\ \hline \end{tabular}
\end{table} 
Table 4: Decorrelation between cells’ and nuclei distributions. Quantitative analysis of karyoplasmic (nuclei/cell) ratios. Correlation coefficients calculated by [PERSON]’s formula for cells and nuclei distributions. Two-minute irradiation reduced the nuclei size slightly as compared to cellular size, while 4 min irradiation increased the nuclei size. The observations indicate different durations of exposure effects cell morphology differently. The control groups show strong positive correlation while the irradiated groups reveal strong decorrelation (weak positive for 2 min exposure and strong negative for 4 and 10 min exposure). Cells under 10 min exposure died before reaching Day 7 and 14 of the observation period following MMW treatment. Indicated values represent the mean of three independent experiments. Figure 4: **(A)** Mortality effect following 4 min of W-band (75–105 GHz) MMW treatment on H1299 cell line. Scale bars correspond to 10 μm. (**B**) The number of cells counted for each group was 400–550. Each experiment was repeated four times. * indicates \(p\)-value \(<\) 0.01. Figure 5: **(A)** Senescence effect following 4 min of W-band (75–105 GHz) MMW treatment on H1299 cell line. Scale bars correspond to 10 μm. (**B**) The number of cells were counted for each group was 400–550. Each experiment was repeated four times. * and # indicates \(p\)-values of \(<\)0.05 and \(<\)0.01 respectively. Senescence occurs in cells during the pro-apoptotic stage and excludes the possibility of division (mitosis). In a normal H1299 cell population, generally about 1-3% of the cells are dead and/or in senescence (ref. Table 1).